WorldWideScience

Sample records for chemical variations observed

  1. Seasonal variation of spherical aerosols distribution in East Asia based on ground and space Lidar observation and a Chemical transport model

    Science.gov (United States)

    Hara, Y.; Yumimoto, K.; Uno, I.; Shimizu, A.; Sugimoto, N.; Ohara, T.

    2009-12-01

    The anthropogenic aerosols largely impact on not only human health but also global climate system, therefore air pollution in East Asia due to a rapid economic growth has been recognized as a significant environmental problem. Several international field campaigns had been conducted to elucidate pollutant gases, aerosols characteristics and radiative forcing in East Asia. (e.g., ACE-Asia, TRACE-P, ADEC, EAREX 2005). However, these experiments were mainly conducted in springtime, therefore seasonal variation of aerosols distribution has not been clarified well yet. National Institute for Environmental Studies (NIES) has been constructing a lidar networks by automated dual wavelength / polarization Mie-lidar systems to observe the atmospheric environment in Asian region since 2001. Furthermore, from June 2006, space-borne backscatter lidar, Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), onboard NASA/CALIPSO satellite, measures continuous global aerosol and cloud vertical distribution with very high spatial resolution. In this paper, we will show the seasonal variation of aerosols distribution in East Asia based on the NIES lidar network observation, Community Multi-scale Air Quality Modeling System (CMAQ) chemical transport model simulation and CALIOP observation over the period from July 2006 to December 2008. We found that CMAQ result explains the typical seasonal aerosol characteristics by lidar observations. For example, CMAQ and ground lidar showed a summertime peak of aerosol optical thickness (AOT) at Beijing, an autumn AOT peak at Guangzhou and summertime AOT trough at Hedo, Okinawa. These characteristics are mainly controlled by seasonal variations of Asian summer/winter monsoon system. We also examined the CMAQ seasonal average aerosol extinction profiles with ground lidar and CALIOP extinction data. These comparisons clarified that the CMAQ reproduced the observed aerosol layer depth well in the downwind region. Ground lidar and CALIOP seasonal

  2. Technical Note: Spectral representation of spatial correlations in variational assimilation with grid point models and application to the belgian assimilation system for chemical observations (BASCOE

    Directory of Open Access Journals (Sweden)

    Q. Errera

    2012-07-01

    Full Text Available The formulation of the background error covariances represented in the spectral space is discussed in the context of univariate assimilation relying on a grid point model, leaving out all the aspects of balances between the different control variables needed in meteorological assimilation. The spectral transform operations are discussed in the case of a spherical harmonics basis and we stress that there is no need for an inverse spectral transform and of a Gaussian grid. The analysis increments are thus produced directly on the model grid. The practice of producing analysis increments on a horizontal Gaussian grid and then interpolating on a equally spaced grid is also shown to produce a degradation of the analysis. The method discussed in this paper allows the implementation of separable and non-separable spatial correlations. The separable formulation has been implemented in the Belgian Assimilation System for Chemical ObsErvations (BASCOE and its impact on the assimilation of O3 observed by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS is shown. To promote the use of this method by other non-meteorological variational systems and in particular chemistry, the Fortran code developed is made available to the community.

  3. Technical Note: Spectral representation of spatial correlations in variational assimilation with grid point models and application to the Belgian Assimilation System for Chemical Observations (BASCOE

    Directory of Open Access Journals (Sweden)

    Q. Errera

    2012-11-01

    Full Text Available The formulation of the background error covariances represented in the spectral space is discussed in the context of univariate assimilation relying on a grid point model, leaving out all the aspects of balances between the different control variables needed in meteorological assimilation. The spectral transform operations are discussed in the case of a spherical harmonics basis and we stress that there is no need for an inverse spectral transform and of a Gaussian grid. The analysis increments are thus produced directly on the model grid. The practice of producing analysis increments on a horizontal Gaussian grid and then interpolating to an equally spaced grid is also shown to produce a degradation of the analysis. The method discussed in this paper allows the implementation of separable and non-separable spatial correlations. The separable formulation has been implemented in the Belgian Assimilation System for Chemical ObsErvations (BASCOE and its impact on the assimilation of O3 observed by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS is shown. To promote the use of this method by other non-meteorological variational systems and in particular chemistry, the Fortran code developed is made available to the community.

  4. Chemical Principle and PDE of Variational Electrodynamics

    CERN Document Server

    De Luca, Jayme

    2016-01-01

    We study the problem of selecting a bounded two-body orbit exerting a vanishing electrical force on a third charge located outside a core region. The former infinite-dimensional PDE problem is called here the Chemical principle for the hydrogenoid atom of variational electrodynamics. For orbits with velocity discontinuities satisfying mild conditions at breaking points we introduce the delay and synchronization functions and prove a musical Lemma of synchronization-at-a-distance. We derive the leading PDE of the Chemical principle by removing the accelerations using the equations of motion approximated by keeping only the terms with the most singular denominators.

  5. Galactic chemical evolution: the observational side

    OpenAIRE

    McWilliam, Andrew

    2010-01-01

    In this review I outline some ideas in chemical evolution, necessary for understanding the evolution of galaxies from measured elemental abundance ratios. I then discuss abundance results from studies of Local Group dwarf galaxies and the globular cluster Omega Cen. I present a qualitative scenario of prolonged chemical enrichment in a leaky box that can explain the observed abundance ratios in these systems. Space limitations prevent a comprehensive review of this vast field, so I have restr...

  6. Experimental study of chemical concentration variation of ASP flooding

    Institute of Scientific and Technical Information of China (English)

    WANG JiaLu; YUAN ShiYi; SHI FaShun; JIA Xu

    2009-01-01

    A physical modeling system of long slim tube was established. Several pressure measuring and sampling points were laid out at different positions along the tube. Through real-time measurements of pressures and chemical concentrations at different points, the mass transfer and chemical concentration of ASP flooding in porous media are studied. The concentration of chemicals declines gradually during the fluid flow from the inlet to the outlet of the model. The concentration increases in the front edge of the slug faster than the concentration decreases in the rear edge of the slug. The concentration variation of the chemicals is an asymmetrical and offset process. The order of motion velocities of the chemicals from fast to slow is polymer, alkali and surfactant. The motion lag and comprehensive diffusion are strong in the vicinity of the inlet, the motion velocities of the chemicals are high, the difference of flow velocities among the three chemicals is significant and the chromatographic separation of the chemicals is obvious. In the area near the outlet, the comprehensive diffusion and motion lag become weak, the concentrations of the chemicals decrease, the motion velocities of the chemicals are slow,the difference among the motion velocities of the chemicals becomes small, the chromatographic separation is not obvious, the adsorption and retention of chemicals gradually increase as the chemical slug moves further along the tube, the adsorption and retention of polymer is the most serious.

  7. Experimental study of chemical concentration variation of ASP flooding

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A physical modeling system of long slim tube was established. Several pressure measuring and sampling points were laid out at different positions along the tube. Through real-time measurements of pressures and chemical concentrations at different points, the mass transfer and chemical concentration of ASP flooding in porous media are studied. The concentration of chemicals declines gradually during the fluid flow from the inlet to the outlet of the model. The concentration increases in the front edge of the slug faster than the concentration decreases in the rear edge of the slug. The concentration variation of the chemicals is an asymmetrical and offset process. The order of motion velocities of the chemicals from fast to slow is polymer, alkali and surfactant. The motion lag and comprehensive diffusion are strong in the vicinity of the inlet, the motion velocities of the chemicals are high, the difference of flow velocities among the three chemicals is significant and the chromatographic separation of the chemicals is obvious. In the area near the outlet, the comprehensive diffusion and motion lag become weak, the concentrations of the chemicals decrease, the motion velocities of the chemicals are slow, the difference among the motion velocities of the chemicals becomes small, the chromatographic separation is not obvious, the adsorption and retention of chemicals gradually increase as the chemical slug moves further along the tube, the adsorption and retention of polymer is the most serious.

  8. An observational correlation between stellar brightness variations and surface gravity

    CERN Document Server

    Bastien, Fabienne A; Basri, Gibor; Pepper, Joshua

    2013-01-01

    Surface gravity is one of a star's basic properties, but it is difficult to measure accurately, with typical uncertainties of 25-50 per cent if measured spectroscopically and 90-150 per cent photometrically. Asteroseismology measures gravity with an uncertainty of about two per cent but is restricted to relatively small samples of bright stars, most of which are giants. The availability of high-precision measurements of brightness variations for >150,000 stars provides an opportunity to investigate whether the variations can be used to determine surface gravities. The Fourier power of granulation on a star's surface correlates physically with surface gravity; if brightness variations on timescales of hours arise from granulation, then such variations should correlate with surface gravity. Here we report an analysis of archival data that reveals an observational correlation between surface gravity and the root-mean-square brightness variations on timescales of less than eight hours for stars with temperatures ...

  9. Atmospheric diurnal variations observed with GPS radio occultation soundings

    Directory of Open Access Journals (Sweden)

    F. Xie

    2010-07-01

    Full Text Available The diurnal variation, driven by solar forcing, is a fundamental mode in the Earth's weather and climate system. Radio occultation (RO measurements from the six COSMIC satellites (Constellation Observing System for Meteorology, Ionosphere and Climate provide nearly uniform global coverage with high vertical resolution, all-weather and diurnal sampling capability. This paper analyzes the diurnal variations of temperature and refractivity from three-year (2007–2009 COSMIC RO measurements in the troposphere and stratosphere between 30° S and 30° N. The RO observations reveal both propagating and trapped vertical structures of diurnal variations, including transition regions near the tropopause where data with high vertical resolution are critical. In the tropics the diurnal amplitude in refractivity shows the minimum around 14 km and increases to a local maximum around 32 km in the stratosphere. The upward propagating component of the migrating diurnal tides in the tropics is clearly captured by the GPS RO measurements, which show a downward progression in phase from stratopause to the upper troposphere with a vertical wavelength of about 25 km. At ~32 km the seasonal variation of the tidal amplitude maximizes at the opposite side of the equator relative to the solar forcing. The vertical structure of tidal amplitude shows strong seasonal variations and becomes asymmetric along the equator and tilted toward the summer hemisphere in the solstice months. Such asymmetry becomes less prominent in equinox months.

  10. Network representations of knowledge about chemical equilibrium: Variations with achievement

    Science.gov (United States)

    Wilson, Janice M.

    This study examined variation in the organization of domain-specific knowledge by 50 Year-12 chemistry students and 4 chemistry teachers. The study used nonmetric multidimensional scaling (MDS) and the Pathfinder network-generating algorithm to investigate individual and group differences in student concepts maps about chemical equilibrium. MDS was used to represent the individual maps in two-dimensional space, based on the presence or absence of paired propositional links. The resulting separation between maps reflected degree of hierarchical structure, but also reflected independent measures of student achievement. Pathfinder was then used to produce semantic networks from pooled data from high and low achievement groups using proximity matrices derived from the frequencies of paired concepts. The network constructed from maps of higher achievers (coherence measure = 0.18, linked pairs = 294, and number of subjects = 32) showed greater coherence, more concordance in specific paired links, more important specific conceptual relationships, and greater hierarchical organization than did the network constructed from maps of lower achievers (coherence measure = 0.12, linked pairs = 552, and number of subjects = 22). These differences are interpreted in terms of qualitative variation in knowledge organization by two groups of individuals with different levels of relative expertise (as reflected in achievement scores) concerning the topic of chemical equilibrium. The results suggest that the technique of transforming paired links in concept maps into proximity matrices for input to multivariate analyses provides a suitable methodology for comparing and documenting changes in the organization and structure of conceptual knowledge within and between individual students.

  11. Variations observed in environmental radiation at ground level

    International Nuclear Information System (INIS)

    To investigate and monitor environmental radiation at ground level, Physikalisch-Technische Bundesanstalt (PTB) has installed several dosemeters and particle detectors at the new Ambient Radiation Dosimetry Site. The separation of the total ambient dose equivalent rate H*(10)env of environmental radiation into the different contributions is achieved by comparing the data of different detectors: the muon detector MUDOS, a modified neutron dosemeter, proportional counters and ionisation chambers. The response of the latter two dosemeter systems to cosmic radiation was determined at the Cosmic Radiation Dosimetry Site on a lake near PTB. Besides the increase of the ambient dose equivalent rate during rainfall, variations owing to air pressure, solar activity and temperature changes in the upper atmosphere are observed. Without rain and solar effects, smooth variations of the cosmic component at ground level of ±6.9 nSv h-1 should be treated as naturally occurring variations during an entire year. (authors)

  12. Temporal Variation of Chemical Persistence in a Swedish Lake Assessed by Benchmarking.

    Science.gov (United States)

    Zou, Hongyan; Radke, Michael; Kierkegaard, Amelie; McLachlan, Michael S

    2015-08-18

    Chemical benchmarking was used to investigate the temporal variation of the persistence of chemical contaminants in a Swedish lake. The chemicals studied included 12 pharmaceuticals, an artificial sweetener, and an X-ray contrast agent. Measurements were conducted in late spring, late autumn, and winter. The transformation half-life in the lake could be quantified for 7 of the chemicals. It ranged from several days to hundreds of days. For 5 of the chemicals (bezafibrate, climbazole, diclofenac, furosemide, and hydrochlorothiazide), the measured persistence was lower in late spring than in late autumn. This may have been caused by lower temperatures and/or less irradiation during late autumn. The seasonality in chemical persistence contributed to changes in chemical concentrations in the lake during the year. The impact of seasonality of persistence was compared with the impact of other important variables determining concentrations in the lake: chemical inputs and water flow/dilution. The strongest seasonal variability in chemical concentration in lake water was observed for hydrochlorothiazide (over a factor of 10), and this was attributable to the seasonality in its persistence. PMID:26171662

  13. EEJ and Sq Variations Observed at MAGDAS/CPMN Stations

    Science.gov (United States)

    Yumoto, K.; Yamazaki, Y.; Abe, S.; Uozumi, T.

    2009-12-01

    The Space Environment Research Center (SERC), Kyushu University has deployed the MAGnetic Data Acqusition System (MAGDAS) at 50 stations along the 210- and 96-degree magnetic meridians (MM) and the magnetic dip equator, and several FM-CW radars along the 210-degree MM during the International Heliophysical Year (IHY) period of 2005-2009 (see http://magdas.serc.kyushu-u.ac.jp/ and http://magdas2.serc.kyushu-u.ac.jp/). The MAGDAS project for space weather will be continued during the Post IHY, i.e., the International Space Weather Initiative (ISWI) period of 2010-2012. The goal of MAGDAS project is to become the most comprehensive ground-based monitoring system of the earth's magnetic field. By analyzing these new MAGDAS data, we can perform a real-time monitoring and modeling of the global (e.g., Sq, EEJ) current system and the ambient plasma mass density for understanding the electromagnetic and plasma environment changes in geospace during helio-magnetospheric storms. In order to examine the propagation mechanisms of transient disturbances, i.e., sc/si, Pi 2, and DP2, relations of ionospheric electric and magnetic fields are also investigated by analyzing the MAGDAS magnetic data and the Doppler data of our FM-CW ionospheric radar. A new EE-index (EDst, EU, and EL) was proposed by SERC for real-time and long-term geo-space monitoring. The basic algorithm to obtain EE-index was constructed by Uozumi et al. (2008). EU and EL mainly represent the range of the EEJ (equatorial electrojet) and CEJ (equatorial counter electrojet) components, respectively. The baseline levels of EU and EL are obtained by averaging the H-component magnetic variations observed at the nightside (LT = 18-06) MAGDAS/CPMN (Circum-pan Pacific Magnetometer Network) stations along the magnetic equator. The baseline value is defined as EDst and its variations are found to be similar to those of Dst. We examined relationships among the EEJ amplitude, the F10.7 solar radiation flux, the solar wind

  14. Variational principles in chemical equilibria: Complex chemical systems with interacting subsystems

    CERN Document Server

    Zilbergleyt, B

    2010-01-01

    The goal of the paper is to derive a revised condition of global equilibrium in complex chemical systems as variational principle in formalism of recently developed discrete thermodynamics (DTD) of chemical equilibria. In classical approach the problem of complex equilibrium is solved by minimization of the system Gibbs’ free energy subject to logistic constraints. DTD demands any isolated system to comprise smaller subentities, which individual equilibria are based on the balance of internal and external thermodynamic forces, acting against them. The internal forces are equal to the subsystems thermodynamic affinities, while external forces originate from subsystems mutual interactions. Those interactions impose additional constraints on the mother system Gibbs’ free energy minimum. Basic expression of discrete thermodynamics, being multiplied by subsystems deviations from their “true” thermodynamic equilibria, is naturally identical to d’Alembert’s principle. A thermodynamic ve...

  15. Detection of Cell Wall Chemical Variation in Zea Mays Mutants Using Near-Infrared Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Buyck, N.; Thomas, S.

    2001-01-01

    Corn stover is regarded as the prime candidate feedstock material for commercial biomass conversion in the United States. Variations in chemical composition of Zea mays cell walls can affect biomass conversion process yields and economics. Mutant lines were constructed by activating a Mu transposon system. The cell wall chemical composition of 48 mutant families was characterized using near-infrared (NIR) spectroscopy. NIR data were analyzed using a multivariate statistical analysis technique called Principal Component Analysis (PCA). PCA of the NIR data from 349 maize leaf samples reveals 57 individuals as outliers on one or more of six Principal Components (PCs) at the 95% confidence interval. Of these, 19 individuals from 16 families are outliers on either PC3 (9% of the variation) or PC6 (1% of the variation), the two PCs that contain information about cell wall polymers. Those individuals for which altered cell wall chemistry is confirmed with wet chemical analysis will then be subjected to fermentation analysis to determine whether or not biomass conversion process kinetics, yields and/or economics are significantly affected. Those mutants that provide indications for a decrease in process cost will be pursued further to identify the gene(s) responsible for the observed changes in cell wall composition and associated changes in process economics. These genes will eventually be incorporated into maize breeding programs directed at the development of a truly dual use crop.

  16. Atmospheric Variations as observed by IceCube

    CERN Document Server

    Tilav, Serap; Kuwabara, Takao; Rocco, Dominick; Rothmaier, Florian; Simmons, Matt; Wissing, Henrike

    2010-01-01

    We have measured the correlation of rates in IceCube with long and short term variations in the South Pole atmosphere. The yearly temperature variation in the middle stratosphere (30-60 hPa) is highly correlated with the high energy muon rate observed deep in the ice, and causes a +/-10% seasonal modulation in the event rate. The counting rates of the surface detectors, which are due to secondary particles of relatively low energy (muons, electrons and photons), have a negative correlation with temperatures in the lower layers of the stratosphere (40-80 hPa), and are modulated at a level of +/-5%. The region of the atmosphere between pressure levels 20-120 hPa, where the first cosmic ray interactions occur and the produced pions/kaons interact or decay to muons, is the Antarctic ozone layer. The anticorrelation between surface and deep ice trigger rates reflects the properties of pion/kaon decay and interaction as the density of the stratospheric ozone layer changes. Therefore, IceCube closely probes the ozon...

  17. Geographic and Temporal Variation in Moth Chemical Communication

    Science.gov (United States)

    Unlike acoustic and visual communication, chemical communication cues have not been viewed in the background of a chemically noisy habitat. Species with similar chemical cues may not only directly interfere with each other's communication channels, but the presence and abundance of other species may...

  18. Static and dynamic variational principles for expectation values of observables

    International Nuclear Information System (INIS)

    A general procedure is first reviewed for constructing variational principles (v.p.) suited to the optimization of a quantity of interest. Conditions under which the solution may be obtained as a maximum rather than as a saddle-point are examined. Applications are then worked out, providing v.p. adapted to the evaluation of expectation values, fluctuations or correlations of quantum observables, whether the system is at thermal equilibrium or whether it has evolved. Another class of v.p. concerns dynamical problems. The general method allows to recover a known time-dependent v.p. for a state and an observable [3,13] which answers the following question. Given the state of the system at the time t0, what is the expectation value at a later time t1. A more general v.p. applies to situations in which the initial state is too complicated to be handled exactly. Both the approximate initial conditions and the approximate evolution are then determined so as to optimize . Finally, analogous v.p. are constructed in classical statistical mechanics and hamiltonian dynamics. A recent formulation of classical mechanics in terms of covariant Poisson brackets [19] comes out naturally in this context from the v.p. for the evaluation of a classical expectation value

  19. Compositional Variations from UVIS Observations of Titan's Dayglow and Comparisons with in situ INMS Observations

    Science.gov (United States)

    Stevens, M. H.; Evans, J. S.; Ajello, J. M.; Bradley, E. T.; Meier, R. R.; Westlake, J. H.; Waite, J. H., Jr.

    2012-04-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed Titan’s dayside limb on multiple occasions between 2007 and 2011. The airglow observations reveal the same variety of EUV (600-1150Å) and FUV (1150-1900Å) emissions arising from photoelectron excitation and photofragmentation of molecular nitrogen (N2) on Earth. Through spectral analysis we extract radiance profiles for each set of UVIS limb emissions in the EUV and FUV, which are attenuated by methane (CH4). Using a terrestrial airglow model adapted to Titan, we derive the N2 and CH4 density profiles using the prescribed solar irradiance for the relevant Cassini orbit and compare the calculated radiance profiles directly with observations. We find that the UVIS airglow observations can be explained by solar driven processes, although fluctuations in the observed airglow between flybys suggest compositional changes in the background atmosphere. We compare the compositional variations inferred from the UVIS airglow to in situ observations by the Cassini Ion and Neutral Mass Spectrometer (INMS) from the same Titan orbit and discuss how the variations may be related to Titan’s varying plasma environment.

  20. Solar cycle variation of gravity waves observed in OH airglow

    Science.gov (United States)

    Gelinas, L. J.; Hecht, J. H.; Walterscheid, R. L.; Reid, I. M.; Woithe, J.; Vincent, R. A.

    2013-12-01

    Airglow imaging provides a unique means by which to study many wave-related phenomena in the 80 to 100 km altitude regime. Two-dimensional image observations reveal quasi-monochromatic disturbances associated with atmospheric gravity waves (AGWs) as well as small-scale instabilities, often called ripples. Image-averaged temperature and intensity measurements can be used to study the response of the airglow layer to tides and planetary waves, as well as monitor longer-term climatological variations. Here we present results of low and mid-latitude OH airglow observations beginning near solar max of solar cycle 23 and continuing through solar max of cycle 24. Aerospace imagers deployed at Alice Springs (23o42'S, 133o53'E) and Adelaide (34o55'S, 138o36'E) have been operating nearly continuously since ~2001. The imagers employ filters measuring OH Meinel (6, 2) and O2 Atmospheric (0, 1) band emission intensities and temperatures, as well as atmospheric gravity wave parameters. The Aerospace Corporation's Infrared Camera deployed at Maui, HI (20.7N,156.3W), collected more than 700 nights of airglow images from 2002-2005. The camera measures the OH Meinel (4,2) emission at 1.6 um using a 1 second exposure at a 3 second cadence, which allows the study of AGW and ripple features over very short temporal and spatial scales. The camera was relocated to Cerro Pachon, Chile (30.1 S, 70.8 W) and has been operating continuously since 2010. Temperature, intensity and gravity wave climatologies derived from the two Australian airglow imagers span a full solar cycle (solar max to solar max). Emission intensities have been calibrated using background stars, and temperatures have been calibrated with respect to TIMED/SABER temperatures, reducing the influence of instrument degradation on the solar cycle climatology. An automated wave detection algorithm is used to identify quasi monochromatic wave features in the airglow data, including wavelength, wave period and propagation

  1. Observations on variational and projector Monte Carlo methods

    International Nuclear Information System (INIS)

    Variational Monte Carlo and various projector Monte Carlo (PMC) methods are presented in a unified manner. Similarities and differences between the methods and choices made in designing the methods are discussed. Both methods where the Monte Carlo walk is performed in a discrete space and methods where it is performed in a continuous space are considered. It is pointed out that the usual prescription for importance sampling may not be advantageous depending on the particular quantum Monte Carlo method used and the observables of interest, so alternate prescriptions are presented. The nature of the sign problem is discussed for various versions of PMC methods. A prescription for an exact PMC method in real space, i.e., a method that does not make a fixed-node or similar approximation and does not have a finite basis error, is presented. This method is likely to be practical for systems with a small number of electrons. Approximate PMC methods that are applicable to larger systems and go beyond the fixed-node approximation are also discussed

  2. Diurnal Variations of Titan's Surface Temperatures From Cassini -CIRS Observations

    Science.gov (United States)

    Cottini, Valeria; Nixon, Conor; Jennings, Don; Anderson, Carrie; Samuelson, Robert; Irwin, Patrick; Flasar, F. Michael

    The Cassini Composite Infrared Spectrometer (CIRS) observations of Saturn's largest moon, Titan, are providing us with the ability to detect the surface temperature of the planet by studying its outgoing radiance through a spectral window in the thermal infrared at 19 m (530 cm-1) characterized by low opacity. Since the first acquisitions of CIRS Titan data the in-strument has gathered a large amount of spectra covering a wide range of latitudes, longitudes and local times. We retrieve the surface temperature and the atmospheric temperature pro-file by modeling proper zonally averaged spectra of nadir observations with radiative transfer computations. Our forward model uses the correlated-k approximation for spectral opacity to calculate the emitted radiance, including contributions from collision induced pairs of CH4, N2 and H2, haze, and gaseous emission lines (Irwin et al. 2008). The retrieval method uses a non-linear least-squares optimal estimation technique to iteratively adjust the model parameters to achieve a spectral fit (Rodgers 2000). We show an accurate selection of the wide amount of data available in terms of footprint diameter on the planet and observational conditions, together with the retrieved results. Our results represent formal retrievals of surface brightness temperatures from the Cassini CIRS dataset using a full radiative transfer treatment, and we compare to the earlier findings of Jennings et al. (2009). The application of our methodology over wide areas has increased the planet coverage and accuracy of our knowledge of Titan's surface brightness temperature. In particular we had the chance to look for diurnal variations in surface temperature around the equator: a trend with slowly increasing temperature toward the late afternoon reveals that diurnal temperature changes are present on Titan surface. References: Irwin, P.G.J., et al.: "The NEMESIS planetary atmosphere radiative transfer and retrieval tool" (2008). JQSRT, Vol. 109, pp

  3. PETN: Variation in Physical and Chemical Characteristics Related to Aging.

    Energy Technology Data Exchange (ETDEWEB)

    Monroe, D. C. (Dierdre Christina); Laintz, K. E. (Kenneth E.); Kramer, J. F. (John F.); Peterson, P. D. (Paul D.)

    2006-01-01

    Physical and chemical analyses of five PETN (pentaerythritol tetranitrate) batches have been conducted to assist in defining powder acceptance criteria for qualification of newly manufactured powders, as well as for examination of potential changes related to aging and thus changes in performance. Results showed that (1) repeatable Fisher Sub-Sieve Sizer measurements (which relate well to historic performance data) could be obtained with consistent sample setup and measurement techniques; (2) BET nitrogen adsorption estimates of surface area correlate well with Fisher measurements and appear less variable; (3) PharmaVision particle size analyses show promise in discriminating among PETN batches; and (4) SEMs are extremely useful in semi-quantitative discrimination among batches. Physical and chemical data will be related to performance data (to be obtained) to develop quantitative physical and chemical tests useful in predicting performance over time, i.e., as powders age.

  4. Chemical maturation of a bivalent aptamer by single domain variation

    DEFF Research Database (Denmark)

    Rohrbach, Falk; Fatthalla, Maha I; Kupper, Tina;

    2012-01-01

    Two-pronged attack: We describe the maturation of a bivalent aptamer by a chemically driven two-step process. From an improved monovalent aptamer subdomain that had been modified by polycyclic aromatic hydrocarbons at individual positions, a mature bivalent variant with superior activities to its...

  5. Relevant Spatial Scales of Chemical Variation in Aplysina aerophoba

    OpenAIRE

    Oriol Sacristan-Soriano; Bernard Banaigs; Becerro, Mikel A.

    2011-01-01

    Understanding the scale at which natural products vary the most is critical because it sheds light on the type of factors that regulate their production. The sponge Aplysina aerophoba is a common Mediterranean sponge inhabiting shallow waters in the Mediterranean and its area of influence in Atlantic Ocean. This species contains large concentrations of brominated alkaloids (BAs) that play a number of ecological roles in nature. Our research investigates the ecological variation in BAs of A. a...

  6. Relevant spatial scales of chemical variation in Aplysina aerophoba.

    Science.gov (United States)

    Sacristan-Soriano, Oriol; Banaigs, Bernard; Becerro, Mikel A

    2011-12-01

    Understanding the scale at which natural products vary the most is critical because it sheds light on the type of factors that regulate their production. The sponge Aplysina aerophoba is a common Mediterranean sponge inhabiting shallow waters in the Mediterranean and its area of influence in Atlantic Ocean. This species contains large concentrations of brominated alkaloids (BAs) that play a number of ecological roles in nature. Our research investigates the ecological variation in BAs of A. aerophoba from a scale of hundred of meters to thousand kilometers. We used a nested design to sample sponges from two geographically distinct regions (Canary Islands and Mediterranean, over 2500 km), with two zones within each region (less than 50 km), two locations within each zone (less than 5 km), and two sites within each location (less than 500 m). We used high-performance liquid chromatography to quantify multiple BAs and a spectrophotometer to quantify chlorophyll a (Chl a). Our results show a striking degree of variation in both natural products and Chl a content. Significant variation in Chl a content occurred at the largest and smallest geographic scales. The variation patterns of BAs also occurred at the largest and smallest scales, but varied depending on which BA was analyzed. Concentrations of Chl a and isofistularin-3 were negatively correlated, suggesting that symbionts may impact the concentration of some of these compounds. Our results underline the complex control of the production of secondary metabolites, with factors acting at both small and large geographic scales affecting the production of multiple secondary metabolites. PMID:22363236

  7. Relevant Spatial Scales of Chemical Variation in Aplysina aerophoba

    Directory of Open Access Journals (Sweden)

    Oriol Sacristan-Soriano

    2011-11-01

    Full Text Available Understanding the scale at which natural products vary the most is critical because it sheds light on the type of factors that regulate their production. The sponge Aplysina aerophoba is a common Mediterranean sponge inhabiting shallow waters in the Mediterranean and its area of influence in Atlantic Ocean. This species contains large concentrations of brominated alkaloids (BAs that play a number of ecological roles in nature. Our research investigates the ecological variation in BAs of A. aerophoba from a scale of hundred of meters to thousand kilometers. We used a nested design to sample sponges from two geographically distinct regions (Canary Islands and Mediterranean, over 2500 km, with two zones within each region (less than 50 km, two locations within each zone (less than 5 km, and two sites within each location (less than 500 m. We used high-performance liquid chromatography to quantify multiple BAs and a spectrophotometer to quantify chlorophyll a (Chl a. Our results show a striking degree of variation in both natural products and Chl a content. Significant variation in Chl a content occurred at the largest and smallest geographic scales. The variation patterns of BAs also occurred at the largest and smallest scales, but varied depending on which BA was analyzed. Concentrations of Chl a and isofistularin-3 were negatively correlated, suggesting that symbionts may impact the concentration of some of these compounds. Our results underline the complex control of the production of secondary metabolites, with factors acting at both small and large geographic scales affecting the production of multiple secondary metabolites.

  8. Variation in size, morphology and chemical composition of polymetallic nodules from the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Valsangkar, A.B.; Karisiddaiah, S.M.; Parthiban, G.

    Chemical composition of 613 polymetallic nodules from 150 stations in the Central Indian Ocean Basin (CIOB) are determined and variations in Mn, Fe, Cu, Ni, Co, Zn and moisture content are studied with respect to their size and surface texture...

  9. THERMAL AND CHEMICAL STRUCTURE VARIATIONS IN TITAN'S STRATOSPHERE DURING THE CASSINI MISSION

    Energy Technology Data Exchange (ETDEWEB)

    Bampasidis, Georgios; Coustenis, A.; Vinatier, S. [Laboratoire d' Etudes Spatiales et d' Instrumentation en Astrophysique (LESIA), Observatoire de Paris, CNRS, UPMC Univ. Paris 06, Univ. Paris-Diderot, 5, place Jules Janssen, F-92195 Meudon Cedex (France); Achterberg, R. K. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Lavvas, P. [GSMA, Universite Reims Champagne-Ardenne, F-51687 Reims Cedex 2 (France); Nixon, C. A.; Jennings, D. E.; Flasar, F. M.; Carlson, R. C.; Romani, P. N.; Guandique, E. A. [Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Teanby, N. A. [School of Earth Sciences, University of Bristol, Bristol BS8 1RJ (United Kingdom); Moussas, X.; Preka-Papadema, P.; Stamogiorgos, S., E-mail: gbabasid@phys.uoa.gr [Faculty of Physics, National and Kapodistrian University of Athens, Panepistimioupolis, GR 15783 Zographos, Athens (Greece)

    2012-12-01

    We have developed a line-by-line Atmospheric Radiative Transfer for Titan code that includes the most recent laboratory spectroscopic data and haze descriptions relative to Titan's stratosphere. We use this code to model Cassini Composite Infrared Spectrometer data taken during the numerous Titan flybys from 2006 to 2012 at surface-intercepting geometry in the 600-1500 cm{sup -1} range for latitudes from 50 Degree-Sign S to 50 Degree-Sign N. We report variations in temperature and chemical composition in the stratosphere during the Cassini mission, before and after the Northern Spring Equinox (NSE). We find indication for a weakening of the temperature gradient with warming of the stratosphere and cooling of the lower mesosphere. In addition, we infer precise concentrations for the trace gases and their main isotopologues and find that the chemical composition in Titan's stratosphere varies significantly with latitude during the 6 years investigated here, with increased mixing ratios toward the northern latitudes. In particular, we monitor and quantify the amplitude of a maximum enhancement of several gases observed at northern latitudes up to 50 Degree-Sign N around mid-2009, at the time of the NSE. We find that this rise is followed by a rapid decrease in chemical inventory in 2010 probably due to a weakening north polar vortex with reduced lateral mixing across the vortex boundary.

  10. High solar cycle spectral variations inconsistent with stratospheric ozone observations

    CERN Document Server

    Ball, W T; Rozanov, E V; Kuchar, A; Sukhodolov, T; Tummon, F; Shapiro, A V; Schmutz, W

    2016-01-01

    Some of the natural variability in climate is understood to come from changes in the Sun. A key route whereby the Sun may influence surface climate is initiated in the tropical stratosphere by the absorption of solar ultraviolet (UV) radiation by ozone, leading to a modification of the temperature and wind structures and consequently to the surface through changes in wave propagation and circulation. While changes in total, spectrally-integrated, solar irradiance lead to small variations in global mean surface temperature, the `top-down' UV effect preferentially influences on regional scales at mid-to-high latitudes with, in particular, a solar signal noted in the North Atlantic Oscillation (NAO). The amplitude of the UV variability is fundamental in determining the magnitude of the climate response but understanding of the UV variations has been challenged recently by measurements from the SOlar Radiation and Climate Experiment (SORCE) satellite, which show UV solar cycle changes up to 10 times larger than p...

  11. Hydrographic and chemical observations in the Sierra Leone River estuary

    International Nuclear Information System (INIS)

    Hydrographic and chemical observations in the Sierra Leone River estuary are reported, a West-African river in the tropics. Because of the typical change between rainy season in the sommer months and dry season in winter time the research work has been adapted to these semi-annual changes. The collected data and results are given and discussed under this aspect of the seasonal fluctuations. (orig.)

  12. Observable consequences of chemical equilibration in energetic heavy ion collisions

    OpenAIRE

    Konopka, Jens; Graf, Harald; Stöcker, Horst; Greiner, Walter

    2006-01-01

    The quantum statistical model (QSM) is used to calculate nuclear fragment distributions in chemical equilibrium. Several observable isotopic effects are predicted for intermediate energy heavy ion collisions. It is demonstrated that particle ratios for different systemsdo not depend on the breakup density-the only free parameter in our model.The importance of entropy measurements is discussed. Specific particle ratios for the system Au-Au are predicted, which can be used to determine the chem...

  13. Chemical Variations in the Rocks of La Primavera Geothermal Field (Mexico) Related with Hydrothermal Alteration

    Energy Technology Data Exchange (ETDEWEB)

    Prol-Ledesma, R.M.; Hernandez-Lombardini, S.I.; Lozano-Santa Cruz, R.

    1995-01-01

    The origin and fate of the components dissolved in the geothermal fluids are of great importance in the study of epithermal deposits, and in the environmental considerations for exploitation of geothermal fields. The chemical study of La Primavera geothermal field in Mexico has environmental importance due to the high arsenic concentration observed in the thermal water and the possible contamination of aquifers in the area. The variations in the chemistry of all altered samples with respect to unaltered samples indicates depletion of manganese, and the alkalis; and enrichment in iron and magnesium. Most samples show an enrichment in aluminum and titanium, and depletion in silica and calcium. Trace elements follow different trends at various depths: shallow depths are more favorable for deposition of the analyzed trace elements than the surface or the deep part of the reservoir.

  14. Short and long term chemical and isotopic variations of Lake Trasimeno (Italy)

    Science.gov (United States)

    Frondini, Francesco; Dragoni, Walter; Chiodini, Giovanni; Caliro, Stefano; Cardellini, Carlo; Donnini, Marco; Morgantini, Nicola

    2016-04-01

    Lake Trasimeno, located in Umbria (central Italy), is a shallow lake of a remarkable naturalistic interest and a significant resource for the economy of the region (Ludovisi and Gaino, 2010; Dragoni, 2004). The Lake Trasimeno has an average area of about 124 km2 with a maximum depth of approximately 5.5 m, has no natural outlet and the volume of water stored is strictly linked to rainfall. In order to limit water level variations in 1898 an efficient outlet was built. At present the water exits from the Lake only when the level reaches a fixed threshold above the outlet channel, so during periods with low precipitation the evaporation becomes the most relevant output from the lake. For instance, between 1989 and 2013 the outlet did not work, and the maximum depth of the lake was reduced to little more than three meters. In the framework of climate change, it is important to understand the changes that could affect Lake Trasimeno in the near future. To this aim it is necessary to individuate the long term trends of the hydrologic, chemical and physical characteristics of the Trasimeno water and distinguish them from the short term variations. At the present it is available a long record of hydrologic data allowing reliable studies on quantitative variations at Lake Trasimeno (Dragoni et al., 2015; Dragoni et al., 2012; Ludovisi and Gaino, 2010), but the definition of the chemical and isotopic trends of lake water it is still a problematic task. On the basis of new chemical and isotopic data, collected from 2006 to 2015, it is possible to observe (i) short term and/or very short (seasonal) variations in temperature, salinity and saturation state with respect to carbonate minerals and a long term trends in isotopic composition of water and total load of mobile species (Cl, Na). The short term variations readily respond to the precipitation regime and are strongly related to lake level; the long term trend is probably related to the progressive increase of near

  15. Seasonal Variation of Some Physico-Chemical Characteristics of Three Major Rivers in Imphal, Manipur: A Comparative Evaluation

    Directory of Open Access Journals (Sweden)

    Th. Alexander Singh

    2013-04-01

    Full Text Available Documentation on water quality based on seasonal distribution pattern of physic-chemical characteristics of the three major rivers flowing in Imphal, Manipur were carried out during July, 2011 to June, 2012. Three main seasons were classified based on the ombothermic information for ten years weather data of Imphal. Significant seasonal variations of the different parameters were observed and the study has a great value in terms of river ecosystem as well as water quality in different seasons

  16. Peroxy radical observations using chemical ionization mass spectrometry during TOPSE

    Science.gov (United States)

    Cantrell, Christopher A.; Edwards, G. D.; Stephens, S.; Mauldin, L.; Kosciuch, E.; Zondlo, M.; Eisele, F.

    2003-03-01

    Peroxy radicals (HO2 + RO2) were measured by chemical conversion-chemical ionization mass spectroscopy in the TOPSE (Tropospheric Ozone Production about the Spring Equinox) campaign that took place February through May 2000. Instrumentation for these measurements was deployed on the NCAR/NSF C-130 aircraft that flew at latitudes from 40 to 85°N, and altitudes from the surface to 7.5 km over the North American continent. The measurements demonstrate the evolution of photochemical activity as time progresses through the study period due to increases in free radical source rates. The increase in average peroxy radical concentration moves northward as the maximum solar elevation and length of sunlit days increase. HOxROx (HO2 + RO2) concentrations are distributed lognormally with means of 11.5 and 7.8 pptv for the middle-latitude band (MLB) and high-latitude band (HLB), respectively. The observations agree well on average with steady state derived concentrations; measurement-model concentration ratios are 1.04 (MLB) and 0.94 (HLB). Concentrations within a given latitude band and altitude region sometimes appear to increase with NOx concentrations, but this correlation nearly disappears at low and moderate NOx levels when the data are parsed by radical production rate; lower radical levels are observed at the highest NOx levels measured (near 1 ppbv). These data are compared with results from other recent observations utilizing a variety of platforms.

  17. Variations in Maternal 5-HTTLPR Affect Observed Sensitive Parenting

    Science.gov (United States)

    Cents, Rolieke A. M.; Kok, Rianne; Tiemeier, Henning; Lucassen, Nicole; Székely, Eszter; Bakermans-Kranenburg, Marian J.; Hofman, Albert; Jaddoe, Vincent W. V.; IJzendoorn, Marinus H.; Verhulst, Frank C.; Lambregtse-van den Berg, Mijke P.

    2014-01-01

    Background: Little is known about the genetic determinants of sensitive parenting. Two earlier studies examined the effect of the serotonin transporter polymorphism (5-HTTLPR) on sensitive parenting, but reported opposite results. In a large cohort we further examined whether 5-HTTLPR is a predictor of observed maternal sensitivity and whether…

  18. Seasonal Variation, Chemical Composition and Antioxidant Activity of Brazilian Propolis Samples

    Directory of Open Access Journals (Sweden)

    Érica Weinstein Teixeira

    2010-01-01

    Full Text Available Total phenolic contents, antioxidant activity and chemical composition of propolis samples from three localities of Minas Gerais state (southeast Brazil were determined. Total phenolic contents were determined by the Folin–Ciocalteau method, antioxidant activity was evaluated by DPPH, using BHT as reference, and chemical composition was analyzed by GC/MS. Propolis from Itapecerica and Paula Cândido municipalities were found to have high phenolic contents and pronounced antioxidant activity. From these extracts, 40 substances were identified, among them were simple phenylpropanoids, prenylated phenylpropanoids, sesqui- and diterpenoids. Quantitatively, the main constituent of both samples was allyl-3-prenylcinnamic acid. A sample from Virginópolis municipality had no detectable phenolic substances and contained mainly triterpenoids, the main constituents being α- and β-amyrins. Methanolic extracts from Itapecerica and Paula Cândido exhibited pronounced scavenging activity towards DPPH, indistinguishable from BHT activity. However, extracts from Virginópolis sample exhibited no antioxidant activity. Total phenolic substances, GC/MS analyses and antioxidant activity of samples from Itapecerica collected monthly over a period of 1 year revealed considerable variation. No correlation was observed between antioxidant activity and either total phenolic contents or contents of artepillin C and other phenolic substances, as assayed by CG/MS analysis.

  19. Observed ozone response to variations in solar ultraviolet radiation

    Science.gov (United States)

    Gille, J. C.; Smythe, C. M.; Heath, D. F.

    1984-01-01

    During the winter of 1979, the solar ultraviolet irradiance varied with a period of 13.5 days and an amplitude of 1 percent. The zonal mean ozone values in the tropics varied with the solar irradiance, with an amplitude of 0.25 to 0.60 percent. This observation agrees with earlier calculations, although the response may be overestimated. These results imply changes in ozone at an altitude of 48 kilometers of up to 12 percent over an 11-year solar cycle. Interpretation of ozone changes in the upper stratosphere will require measurements of solar ultraviolet radiation at wavelengths near 200 nanometers.

  20. Gravity Variation in Siberia: GRACE Observation and Possible Causes

    Directory of Open Access Journals (Sweden)

    Benjamin Fong Chao

    2011-01-01

    Full Text Available We report the finding, from the GRACE observation, of an increasing trend in the gravity anomaly in Siberia at the rate of up to 0.5 ugal yr-1 during 2003/1 - 2009/12, in the backdrop of a negative anomaly of magnitude on the order of ~-10 mgal. In consideration of the non-uniqueness of the gravitational inverse problem, we examine in some detail the various possible geophysical causes to explain the increasing gravity signal. We find two geophysical mechanisms being the most plausible, namely the melting of permafrost and the GIA post-glacial rebound. We conclude that these two mechanisms cannot be ruled out as causes for the regional gravity increase in Siberia, based on gravity data and in want of ancillary geophysical data in the region. More definitive identification of the contributions of the various causes awaits further studies.

  1. Inter-observer variation of chest radiography for pneumoconiosis

    International Nuclear Information System (INIS)

    In order to assess the inter-obeserver variability in the interpretation of chest radiographs for the diagnosis of pneumoconiosis, 1040 radiographs were re-read simultaneously by four radiologists. The radiographs had been performed previously by 8 different radiology services on workers exposed to low silica content dust (<5%). Assessment of variability by pairs of readers was performed by calculating the ''k'' coefficient, as proposed by fleiss, which permits measurement of agreement of diagnosis, escluding any change agreement. Agreement of diagnosis for profusion of lung opacities was satisfactory (k 0.39 -0.68) for all the categories considered as a whole, but some categories (0/1 in particular), coefficients were recorded that were significantly lower than 0.4 (the value taken as the minimum agreement limit). The percentage of ''negative'' radiological pictures (0/0 in this case and the technical quality of radiographs did not affect agreement. There was substantial variability of interpretation particulary between one radiologist and the other three, but agreement between radiologist with greater experience was very good (k=0.6). An attempt is made to explain the greater variability observed in classifying category 0/1, which could depend on the definition of the category itself or on its interpretation

  2. Surprising variations in the rotation of the chemically peculiar stars CU Virginis and V901 Orionis

    CERN Document Server

    Mikulasek, Zdenek; Henry, Gregory W; Janik, Jan; Zverko, Juraj; Ziznovsky, Jozef; Zejda, Miloslav; Liska, Jiri; Zverina, Pavel; Kudryavtsev, Dmitry O; Romanyuk, Iosif I; Sokolov, Nikolay A; Lüftinger, Theresa; Trigilio, Corrado; Neiner, Coralie; de Villiers, Stephanus N; 10.1051/0004-6361/201117784

    2011-01-01

    CU Vir and V901 Ori belong among these few magnetic chemically peculiar stars whose rotation periods vary on timescales of decades. We aim to study the stability of the periods in CU Vir and V901 Ori using all accessible observational data containing phase information. We collected all available relevant archived observations supplemented with our new measurements of these stars and analysed the period variations of the stars using a novel method that allows for the combination of data of diverse sorts. We found that the shapes of their phase curves were constant, while the periods were changing. Both stars exhibit alternating intervals of rotational braking and acceleration. The rotation period of CU Vir was gradually shortening until the year 1968, when it reached its local minimum of 0.52067198 d. The period then started increasing, reaching its local maximum of 0.5207163 d in the year 2005. Since that time the rotation has begun to accelerate again. We also found much smaller period changes in CU Vir on a...

  3. MR pelvimetry measurements, analysis of inter- and intra-observer variation

    Energy Technology Data Exchange (ETDEWEB)

    Korhonen, U., E-mail: ulla.korhonen@pkssk.f [Department of Obstetrics and Gynecology, Kuopio University Hospital (Finland); Department of Obstetrics and Gynecology, North Carelian Central Hospital, Joensuu (Finland); Solja, R. [Department of Obstetrics and Gynecology, North Carelian Central Hospital, Joensuu (Finland); Laitinen, J. [Department of Radiology, North Carelian Central Hospital, Joensuu (Finland); Heinonen, S. [Department of Obstetrics and Gynecology, Kuopio University Hospital (Finland); Taipale, P. [Department of Obstetrics and Gynecology, Kuopio University Hospital (Finland); Department of Obstetrics and Gynecology, Iisalmi Hospital, Iisalmi (Finland)

    2010-08-15

    Objective: To set reference standards and then to evaluate the measurement variation in magnetic resonance (MR) pelvimetry between observations and observers. Methods: The study was carried out retrospectively using 100 MR pelvimetry examinations performed in North Carelian Central Hospital between September 2006 and January 2008. Pelvimetric parameters of pelvic inlet and outlet were measured four times to determine the standard reference for each measurement and then intra- and inter-observer variations were compared. Results: The accuracy of MR pelvimetry, defined as a deviation of <5 mm from the reference standard, was better in pelvic inlet measurements than in the corresponding outlet measurements (95-99% vs. 86-89%). Intra-observer variation was acceptable in all of the measurements with intraclass correlation coefficient (ICC) in the range 0.956-0.981 in all parameters. Inter-observer variation was higher than intra-observer variation. The largest variation of measurements was in pelvic outlet parameters between observers with the ICC in the range of 0.710-0.813. Conclusion: MR pelvimetry measurement should be conducted in a centralized location to decrease observer-related variation. Clinicans should be aware that millimeter differences are not reliable in MR pelvimetry and therefore the use of millimeter accurate limits are not recommended in obstetric decision making.

  4. MR pelvimetry measurements, analysis of inter- and intra-observer variation

    International Nuclear Information System (INIS)

    Objective: To set reference standards and then to evaluate the measurement variation in magnetic resonance (MR) pelvimetry between observations and observers. Methods: The study was carried out retrospectively using 100 MR pelvimetry examinations performed in North Carelian Central Hospital between September 2006 and January 2008. Pelvimetric parameters of pelvic inlet and outlet were measured four times to determine the standard reference for each measurement and then intra- and inter-observer variations were compared. Results: The accuracy of MR pelvimetry, defined as a deviation of <5 mm from the reference standard, was better in pelvic inlet measurements than in the corresponding outlet measurements (95-99% vs. 86-89%). Intra-observer variation was acceptable in all of the measurements with intraclass correlation coefficient (ICC) in the range 0.956-0.981 in all parameters. Inter-observer variation was higher than intra-observer variation. The largest variation of measurements was in pelvic outlet parameters between observers with the ICC in the range of 0.710-0.813. Conclusion: MR pelvimetry measurement should be conducted in a centralized location to decrease observer-related variation. Clinicans should be aware that millimeter differences are not reliable in MR pelvimetry and therefore the use of millimeter accurate limits are not recommended in obstetric decision making.

  5. Diagnostic quality and observer variation in radiographic diagnoses of approximal caries

    International Nuclear Information System (INIS)

    The aim of the study was to compare observer variations, observer strategy, and diagnostic quality with regard to radiographic caries diagnoses made at different depth levels. Qualitative assessment of approximal carious lesions on the basis of radiographs were made for sound (n=28) and carious (n=123) lesions by seven dentists. The inter- and intra-observer variations were lowest when lesions were diagnosed as being in the outermost parts of the teeth. The frequency of false positive scores was lower when dentin was examined as compared with enamel. The quality of radiographic diagnoses showed small variations (p>0.05) when different levels of pulpal depths were interpreted

  6. Decreased 3D observer variation with matched CT-MRI, for target delineation in nasopharynx cancer

    NARCIS (Netherlands)

    Rasch, C.R.; Steenbakkers, R.J.; Fitton, I.; Duppen, J.C.; Nowak, P.J.; Pameijer, F.A.; Eisbruch, A.; Kaanders, J.H.A.M.; Paulsen, F.; Herk, M. van

    2010-01-01

    PURPOSE: To determine the variation in target delineation of nasopharyngeal carcinoma and the impact of measures to minimize this variation. MATERIALS AND METHODS: For ten nasopharyngeal cancer patients, ten observers each delineated the Clinical Target Volume (CTV) and the CTV elective. After 3D an

  7. Decreased 3D observer variation with matched CT-MRI, for target delineation in Nasopharynx cancer

    NARCIS (Netherlands)

    C.R.N. Rasch (Coen); R.J.H.M. Steenbakkers (Roel); I. Fitton (Isabelle); J.C. Duppen (Joop); P.J.C.M. Nowak (Peter); F.A. Pameijer (Frank); A. Eisbruch (Avraham); J.H.A.M. Kaanders (Johannes); F. Paulsen (Frank); M. Herk (Marcel)

    2010-01-01

    textabstractPurpose: To determine the variation in target delineation of nasopharyngeal carcinoma and the impact of measures to minimize this variation.Materials and methods: For ten nasopharyngeal cancer patients, ten observers each delineated the Clinical Target Volume (CTV) and the CTV elective.

  8. Some observations of the variations in natural gamma radiation due to rainfall

    International Nuclear Information System (INIS)

    Results of observations of variations in natural gamma-radiation flux densities due to rainfall are presented and discussed in relation to rate of rainfall. Variations of fluences with amounts of rainfall are also described. It is concluded that the frequency distribution of the ratio of the fluence to the amount of rainfall has a trend to be lognormal

  9. A new comprehensive set of elemental abundances in DLAs - II. Data analysis and chemical variation studies

    CERN Document Server

    Dessauges-Zavadsky, M; D'Odorico, S; Calura, F; Matteucci, F

    2005-01-01

    We present new elemental abundance studies of seven damped Lyman-alpha systems (DLAs). Together with the four DLAs analyzed in Dessauges-Zavadsky et al. (2004), we have a sample of eleven DLA galaxies with uniquely comprehensive and homogeneous abundance measurements. These observations allow one to study the abundance patterns of 22 elements and the chemical variations in the interstellar medium of galaxies outside the Local Group. Comparing the gas-phase abundance ratios of these high redshift galaxies, we found that they show low RMS dispersions, reaching only up 2-3 times the statistical errors for the majority of elements. This uniformity is remarkable given that the quasar sightlines cross gaseous regions with HI column densities spanning over one order of magnitude and metallicities ranging from 1/55 to 1/5 solar. The gas-phase abundance patterns of interstellar medium clouds within the DLA galaxies detected along the velocity profiles show, on the other hand, a high dispersion in several abundance rat...

  10. Solar luminosity variation on short time scales - Observational evidence and basic mechanisms

    International Nuclear Information System (INIS)

    Temporal variations in total solar luminosity on time scales between 100 and 10 to the 9th sec are discussed. Following a brief historical review of solar constant measurements, observations of solar luminosity and its variations made by ground-level radiometry, radiometry from balloons, aircraft and rockets, continuous radiometry from space probes and satellites, measurements of reflected light from solar system bodies, and measurements of solar line depths and limb darkening are presented which demonstrate solar constant variations of less than 1.2% since 1962, no variation over a period of 30 years in the range 0.34 and 2.4 microns, and an influence of magnetic activity. Specific processes which may account for these variations are then examined, including heat flux perturbations due to local variations in thermal impedance, variations in convective heat transport efficiency, energy storage in magnetic fields, and variations in wave heating at the photosphere. Comparison of solar evidence with evidence of luminosity variations in other late-type stars indicates that magnetic activity can influence luminosity on time scales from days to tens of years. Future prospects for experimental observations from spacecraft and from the ground are indicated

  11. Seasonal variations in the physico-chemical characteristics of aerosols in North Taiwan

    Science.gov (United States)

    Chou, Charles

    2014-05-01

    From 2007 to 2012, this study investigated the mass concentration and chemical composition of ambient aerosols (i.e. PM10, PM2.5, and PMc = PM10-PM2.5) at Cape Fuguei, Yangminshan, and NTU (National Taiwan University) stations in northern Taiwan. It was found that the concentration and composition of aerosols exhibited significant seasonal variations but without an inter-annual trend during the study period. Moderate correlations (R2 = 0.4-0.6) were observed among the aerosol concentrations at the respective stations, indicating that the aerosol concentrations were dominated by factors on regional scales. During the seasons of northeasterly winter monsoons, long range transport of dust and particulate air pollutants from the Asia Continent had negatively impacted the atmospheric environment in this area. On the other hand, as a highly developed urban area, Taipei has substantial local emissions of air pollutants that should have transported to the surrounding areas of Taipei basin and caused deterioration of air quality and visibility in Cape Fuguei and Yangminshan. The results indicated that the major components of aerosols in Taipei include sulfate, sea salts, dust, and organic matters. In addition, contributions from nitrate, ammonium, and elemental carbon were also significant. In terms of mass concentration, most of the sea salts and dust particles existed in the coarse mode of aerosols, whereas sulfate and EC were confined within PM2.5. This suggests that the dust and sea salts particles were externally mixed with EC and sulfate in the aerosols over Taipei area. Further, it was found that nitrate were closely associated with sea salts in aerosols, suggesting the reaction between nitric acid and sea salt particles. Different seasonality was observed for sea salt and dust: sea salts peaked in fall and dust reached the maximal level in springtime, implying their sources were regulated by independent seasonal factors. Particulate pollutants (i.e. sulfate, nitrate

  12. THE EXTRAORDINARY FAR-INFRARED VARIATION OF A PROTOSTAR: HERSCHEL/PACS OBSERVATIONS OF LRLL54361

    Energy Technology Data Exchange (ETDEWEB)

    Balog, Zoltan; Detre, Örs H.; Bouwmann, Jeroen; Nielbock, Markus; Klaas, Ulrich; Krause, Oliver; Henning, Thomas [Max Planck Institute for Astronomy Königstuhl 17, Heidelberg D-69117 (Germany); Muzerolle, James [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Flaherty, Kevin [Astronomy Department, Wesleyan University, Middletown, CT 06459 (United States); Furlan, Elise [Natinal Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States); Gutermuth, Rob [Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States); Juhasz, Attila [Leiden Observatory, Leiden University, Niels Bohrweg 2, NL-2333-CA Leiden (Netherlands); Bally, John [CASA, University of Colorado, CB 389, Boulder, CO 80309 (United States); Marton, Gabor, E-mail: balog@mpia.de [Konkoly Observatory, Research Center for Astronomy and Earth Sciences, Hungarian Academy of Sciences, Konkoly Thege 15-17, 1121 Budapest (Hungary)

    2014-07-10

    We report Herschel/Photodetector Array Camera and Spectrometer (PACS) photometric observations at 70 μm and 160 μm of LRLL54361—a suspected binary protostar that exhibits periodic (P = 25.34 days) flux variations at shorter wavelengths (3.6 μm and 4.5 μm) thought to be due to pulsed accretion caused by binary motion. The PACS observations show unprecedented flux variation at these far-infrared wavelengths that are well correlated with the variations at shorter wavelengths. At 70 μm the object increases its flux by a factor of six while at 160 μm the change is about a factor of two, consistent with the wavelength dependence seen in the far-infrared spectra. The source is marginally resolved at 70 μm with varying FWHM. Deconvolved images of the sources show elongations exactly matching the outflow cavities traced by the scattered light observations. The spatial variations are anti-correlated with the flux variation, indicating that a light echo is responsible for the changes in FWHM. The observed far-infrared flux variability indicates that the disk and envelope of this source is periodically heated by the accretion pulses of the central source, and suggests that such long wavelength variability in general may provide a reasonable proxy for accretion variations in protostars.

  13. Strato-mesospheric ClO observations by SMILES: error analysis and diurnal variation

    OpenAIRE

    T. O. Sato; Sagawa, H.; D. Kreyling; Manabe, T.; Ochiai, S.; Kikuchi, K.; Baron, P.; J. Mendrok; Urban, J.; D. Murtagh; M. Yasui; Kasai, Y.

    2012-01-01

    Chlorine monoxide (ClO) is the key species for anthropogenic ozone losses in the middle atmosphere. We observed ClO diurnal variations using the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on the International Space Station, which has a non-sun-synchronous orbit. This includes the first global observations of the ClO diurnal variation from the stratosphere up to the mesosphere. The observation of mesospheric ClO was possible due to 10–20 times better signal-to-noise (S/N...

  14. Observed variations in stratification and currents in the Zuari estuary, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Sundar, D.; Unnikrishnan, A.S.; Michael, G.S.; Kankonkar, A.; Nidheesh, A.G.; Subeesh, M.P.

    of observation, as re-deployment of RCM mooring precisely at the very same spot is not possible. However, the range of variation of rotation angles is within 10o in all observations, which is well within the accuracy, ±10o of the direction sensor...

  15. Observer-based H-infinity output feedback control with feedback gain and observer gain variations for Delta operator system

    Institute of Scientific and Technical Information of China (English)

    Ruiquan LIN; Fuwen YANG; Renchong PENG

    2009-01-01

    Considering that the controller feedback gain and the observer gain are of additive norm-bounded variations, a design method of observer-based H-infinity output feedback controller for uncertain Delta operator systems is proposed in this paper. A sufficient condition of such controllers is presented in linear matrix inequality (LMI) forms. A numerical example is then given to illustrate the effectiveness of this method, that is, the obtained controller guarantees the closed-loop system asymptotically stable and the expected H-infinity performance even if the controller feedback gain and the observer gain are varied.

  16. Inter-observer variation in masked and unmasked images for quality evaluation of clinical radiographs

    International Nuclear Information System (INIS)

    Purpose: To investigate the influence of masking on the inter-observer variation in image quality evaluation of clinical radiographs of chest and lumbar spine. Background: Inter-observer variation is a big problem in image quality evaluation since this variation is often much bigger than the variation in image quality between, for example, two radiographic systems. In this study, we have evaluated the effect of masking on the inter-observer variation. The idea of the masking was to force every observer to view exactly the same part of the image and to avoid the effect of the overall 'first impression' of the image. A discussion with a group of European expert radiologists before the study indicated that masking might be a good way to reduce the inter-observer variation. Methods: Five chest and five lumbar spine radiographs were collected together with detailed information regarding exposure conditions. The radiographs were digitised with a high-performance scanner and five different manipulations were performed, simulating five different exposure conditions. The contrast, noise and spatial resolution were manipulated by this method. The images were printed onto the film and the individual masks were produced for each film, showing only the parts of the images that were necessary for the image quality evaluation. The quality of the images was evaluated on ordinary viewing boxes by a large group of experienced radiologists. The images were examined with and without the masks with a set of image criteria (if fulfilled, 1 point; and not fulfilled, 0 point), and the mean score was calculated for each simulated exposure condition. Results: The results of this study indicate that - contrary to what was supposed - the inter-observer variation increased when the images were masked. In some cases, especially for chest, this increase was statistically significant. Conclusions: Based on the results of this study, image masking in studies of fulfilment of image criteria cannot

  17. Lidar observation campaigns on diurnal variations of the sodium layer in Beijing, China

    Science.gov (United States)

    Wang, Jihong

    2016-07-01

    Based on observations from daytime lidars in eastern China, diurnal cycles of the sodium layer over Beijing (40.5°N, 116°E) are investigated. Diurnal variations of Na density, root mean square (RMS) layer width, and centroid height of the sodium layer are analyzed. Results reveal that the large diurnal cycles of the sodium layer are controlled mainly by 24-hr oscillations at the Beijing observation site. The diurnal variation over Beijing was controlled principally by photoionization and photochemistry effects during another campaign, and there was little evidence of direct tidal perturbations. The comparisons suggest that the diurnal variation of the sodium layer perhaps has obvious regional characteristics across China. The variation can be either controlled mainly by tidal perturbations or by photoionization and photochemistry effects in different seasons.

  18. Present day sea level changes: observation and causes; Les variations actuelles du niveau de la mer: observations et causes

    Energy Technology Data Exchange (ETDEWEB)

    Lombard, A

    2005-11-15

    Whereas sea level has changed little over the last 2000 years, it has risen at a rate of about 2 mm/year during the 20. century. This unexpected sea level rise has been attributed to the anthropogenic global warming, recorded over several decades. Sea level variations have been measured globally and precisely for about 12 years due to satellite altimeter missions Topex/Poseidon and Jason-1. These observations indicate a global mean sea level rise of about 3 mm/year since 1993, a value significantly larger than observed during previous decades. Recent observations have allowed us to quantify the various climatic factors contributing to observed sea level change: thermal expansion of sea water due to ocean warming, melting of mountain glaciers and ice sheets, and changes in the land water reservoirs. A water budget based on these new observations allows us to partly explain the observed sea level rise. In particular, we show that the thermal expansion explains only 25% of the secular sea level rise as recorded by tide-gauges over the last 50 years, while it contributes about 50% of sea level rise observed over the last decade. Meanwhile, recent studies show that glacier and ice sheet melting could contribute the equivalent of 1 mm/year in sea level rise over the last decade. In addition, the high regional variability of sea level trends revealed by satellite altimetry is mainly due to thermal expansion. There is also an important decadal spatio-temporal variability in the ocean thermal expansion over the last 50 years, which seems to be controlled by natural climate fluctuations. We question for the first time the link between the decadal fluctuations in the ocean thermal expansion and in the land reservoirs, and indeed their climatic contribution to sea level change. Finally a preliminary analysis of GRACE spatial gravimetric observations over the oceans allows us to estimate the seasonal variations in mean sea level due to ocean water mass balance variations

  19. Surface Freshwater Storage Variations in the Orinoco Floodplains Using Multi-Satellite Observations

    OpenAIRE

    Frédéric Frappart; Fabrice Papa; Yoann Malbeteau; Juan Gabriel León; Guillaume Ramillien; Catherine Prigent; Lucía Seoane; Frédérique Seyler; Stéphane Calmant

    2014-01-01

    Variations in surface water extent and storage are poorly characterized from regional to global scales. In this study, a multi-satellite approach is proposed to estimate the water stored in the floodplains of the Orinoco Basin at a monthly time-scale using remotely-sensed observations of surface water from the Global Inundation Extent Multi-Satellite (GIEMS) and stages from Envisat radar altimetry. Surface water storage variations over 2003-2007 exhibit large interannual variability and a str...

  20. Latitudinal variations in Titan's methane and haze from Cassini VIMS observations

    Science.gov (United States)

    Penteado, P.F.; Griffith, C.A.; Tomasko, M.G.; Engel, S.; See, C.; Doose, L.; Baines, K.H.; Brown, R.H.; Buratti, B.J.; Clark, R.; Nicholson, P.; Sotin, C.

    2010-01-01

    We analyze observations taken with Cassini's Visual and Infrared Mapping Spectrometer (VIMS), to determine the current methane and haze latitudinal distribution between 60??S and 40??N. The methane variation was measured primarily from its absorption band at 0.61 ??m, which is optically thin enough to be sensitive to the methane abundance at 20-50 km altitude. Haze characteristics were determined from Titan's 0.4-1.6 ??m spectra, which sample Titan's atmosphere from the surface to 200 km altitude. Radiative transfer models based on the haze properties and methane absorption profiles at the Huygens site reproduced the observed VIMS spectra and allowed us to retrieve latitude variations in the methane abundance and haze. We find the haze variations can be reproduced by varying only the density and single scattering albedo above 80 km altitude. There is an ambiguity between methane abundance and haze optical depth, because higher haze optical depth causes shallower methane bands; thus a family of solutions is allowed by the data. We find that haze variations alone, with a constant methane abundance, can reproduce the spatial variation in the methane bands if the haze density increases by 60% between 20??S and 10??S (roughly the sub-solar latitude) and single scattering absorption increases by 20% between 60??S and 40??N. On the other hand, a higher abundance of methane between 20 and 50 km in the summer hemisphere, as much as two times that of the winter hemisphere, is also possible, if the haze variations are minimized. The range of possible methane variations between 27??S and 19??N is consistent with condensation as a result of temperature variations of 0-1.5 K at 20-30 km. Our analysis indicates that the latitudinal variations in Titan's visible to near-IR albedo, the north/south asymmetry (NSA), result primarily from variations in the thickness of the darker haze layer, detected by Huygens DISR, above 80 km altitude. If we assume little to no latitudinal methane

  1. Assessment of BeiDou differential code bias variations from multi-GNSS network observations

    Science.gov (United States)

    Jin, S. G.; Jin, R.; Li, D.

    2016-02-01

    The differential code bias (DCB) of global navigation satellite systems (GNSSs) affects precise ionospheric modeling and applications. In this paper, daily DCBs of the BeiDou Navigation Satellite System (BDS) are estimated and investigated from 2-year multi-GNSS network observations (2013-2014) based on global ionospheric maps (GIMs) from the Center for Orbit Determination in Europe (CODE), which are compared with Global Positioning System (GPS) results. The DCB of BDS satellites is a little less stable than GPS solutions, especially for geostationary Earth orbit (GEO) satellites. The BDS GEO observations decrease the precision of inclined geosynchronous satellite orbit (IGSO) and medium Earth orbit (MEO) DCB estimations. The RMS of BDS satellites DCB decreases to about 0.2 ns when we remove BDS GEO observations. Zero-mean condition effects are not the dominant factor for the higher RMS of BDS satellites DCB. Although there are no obvious secular variations in the DCB time series, sub-nanosecond variations are visible for both BDS and GPS satellites DCBs during 2013-2014. For satellites in the same orbital plane, their DCB variations have similar characteristics. In addition, variations in receivers DCB in the same region are found with a similar pattern between BDS and GPS. These variations in both GPS and BDS DCBs are mainly related to the estimated error from ionospheric variability, while the BDS DCB intrinsic variation is in sub-nanoseconds.

  2. EXPERIMENTAL STUDY OF CHEMICAL CHOLECYSTECTOMY: OBSERVATION OF PATHOLOGICAL CHANGES

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective: TO verify through animal experiment the validity of chemical cholecystectomy . Methods: The experimental objects seven healthy juvenile pigs,hardener was infused into the gallbladder,after infusion the samples were collected by pathoiogical examination , according to the different duration under anesthestize. Reslts:The mucous destructive and digestive process remained with one week, the inflammatory reacton in two weeks,the chronic inflatoy reaction compained a a great deal of granu lation tissue and scar formation occurred in 4th-8th week,10 weeks latter,the inflmmatory reaction reduced ,and scar tissue formed. Conclusion: Chemical cholecystectomy is safe and reliable in clinical.

  3. EXPERIMENTAL STUDY OF CHEMICAL CHOLECYSTECTOMY OF PATHOLOGIC OBSERVATION

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objective:To verify through animal experiment the validity of chemical cholecystectomy.Mothods:The expermental objects seven healthy juvenile pigs,hardener was infused into the gallbladder,after infusion the sapmles were collected by pathological examination,according to the different duration under anesthestize.Results:The mucous destructive and digestive process remained with one week,the inflammatory reaction in two weeks,the chronic inflammatory reaction compained a great deal of granulation tissue and scar formation occurred in 4th-8th week,10 weeks latter,the inflammatory reaction reduced,and scar tissue formed.Conlusion:Chemical cholecystecomy is safe and reliable in clinic.

  4. Ecological consequences, genetic and chemical variations in fragmented populations of a medicinal plant, justicia adhatoda and implications for its conservation

    International Nuclear Information System (INIS)

    Justicia adhatoda from Kohat Plateau was selected for genetic diversity studies, due to its fragmented habitat, importance in traditional and pharmaceutical medicine and a lack of population structure studies. We had two hypotheses: that habitat loss posed a greater threat to populations than loss of genetic diversity, and that chemical diversity would be higher among different populations than within populations. Genetic diversity within and among populations was evaluated using PBA (P450 based analogue) markers. AMOVA analysis revealed that there was higher genetic diversity within populations (90%) than among populations (10%). No genetic drift was observed, i.e., genetic diversity within populations was maintained despite fewer numbers of individuals in fragmented populations. Surveys of J. adhatoda populations revealed that they were growing in harsh conditions and were imperiled due to extensive harvesting for commercial and domestic purposes. Chemical diversity was evaluated by GC-MS (Gas Chromatograph-Mass Spectrometry) analysis of 90% methanol and 1:2 chloroform:methanol extracts. GC-MS analysis of both the extracts showed nine and 18 chemical compounds, respectively, with higher chemical variations among populations. It is therefore recommended that efforts for the conservation of severely fragmented populations of J. adhatoda must be carried out along with sustainable harvesting. (author)

  5. The impact of chemical evolution on the observable properties of stellar populations

    OpenAIRE

    Tosi., M

    2000-01-01

    The major effects of the chemical evolution of galaxies on the characteristics of their stellar populations are reviewed. A few examples of how the observed stellar properties derived from colour--magnitude diagrams can constrain chemical evolution models are given.

  6. PNe as observational constraints in chemical evolution models for NGC 6822

    OpenAIRE

    Hernández-Martínez, L.; L. Carigi; Peña, M. (Marian); M. Peimbert

    2011-01-01

    Chemical evolution models are useful for understanding the formation and evolution of stars and galaxies. Model predictions will be more robust as more observational constraints are used. We present chemical evolution models for the dwarf irregular galaxy NGC 6822 using chemical abundances of old and young Planetary Nebulae (PNe) and \\ion{H}{ii} regions as observational constraints. Two sets of chemical abundances, one derived from collisionally excited lines (CELs) and one, from recombinatio...

  7. Analysis of L5 phase variations in GPS IIF satellites by the raw observation PPP approach

    Science.gov (United States)

    Liu, Sha; Becker, Matthias

    2015-04-01

    GPS modernization along with Glonass modernization and the emerging Galileo and Compass system has been highly anticipated by every GNSS user since several years. The third civilian L5 signal transmitted by the modernized GPS satellites brings us to the GNSS multi-frequency era. The first GPS IIF satellite was launched in May 2010, until now there are eight block IIF satellites in service and the remaining four IIF satellites are planned to be launched by 2016. The introduction of the third frequency to GPS and the usage of advanced atomic clocks not only provide the users more possibilities but also enable higher positioning accuracy. Nevertheless phase variations are found on the new L5 observation of GPS SVN62. Further investigations suggest that the variations of this satellite are strongly dependent on the satellite inner temperature variation caused by sun illumination. Besides achieving precise positioning accuracy, PPP is also frequently used as a tool to analyze and evaluate various GNSS errors, for instance, tropospheric delays and receiver clock errors. Other than with differential GNSS, it is possible to separate different errors and to identify the error sources with PPP. Conventional PPP is based on the ionosphere-free linear combination, in order to eliminate the first-order ionospheric delays. However only dual frequencies can be used to build ionosphere-free linear combination, which leads to the waste of the information on the third frequency. Furthermore, the frequency dependent errors can not be separated and traced. A new PPP approach that avoids using any linear combination is proposed recently, which is called the raw observation PPP. One advantage of the raw observation PPP approach is that data of all frequencies and all GNSS systems can be jointly used. In addition, the frequency dependent errors are possible to be separated, identified and analyzed. In this paper the raw observation PPP is utilized to analyze the phase variations on L5

  8. Validating Arguments for Observational Instruments: Attending to Multiple Sources of Variation

    Science.gov (United States)

    Hill, Heather C.; Charalambous, Charalambos Y.; Blazar, David; McGinn, Daniel; Kraft, Matthew A.; Beisiegel, Mary; Humez, Andrea; Litke, Erica; Lynch, Kathleen

    2012-01-01

    Measurement scholars have recently constructed validity arguments in support of a variety of educational assessments, including classroom observation instruments. In this article, we note that users must examine the robustness of validity arguments to variation in the implementation of these instruments. We illustrate how such an analysis might be…

  9. Diurnal variation of ducts observed over a tropical station, Gadanki, using high-resolution GPS radiosonde observations

    Science.gov (United States)

    Manjula, G.; Roja Raman, M.; Venkat Ratnam, M.; Chandrasekhar, A. V.; Vijaya Bhaskara Rao, S.

    2016-04-01

    A comprehensive study on diurnal variation of ducting using high vertical and temporal resolution radiosonde measurements over the Indian tropical region, Gadanki (13.5°N, 79.2°E), was presented. The diurnal variation of ducts was examined statistically based on both the refractivity and modified refractivity using 3-hourly radiosonde soundings obtained during October 2010 to March 2014 as a part of tropical tropopause dynamics (TTD) campaigns conducted under Climate and Weather of Sun Earth System (CAWSES) India Phase II program. Strong diurnal variation in the altitude of occurrence of the duct has been found and is at maximum altitude (~2.5 km) during 11-17 LT. Interestingly, it is found that the occurrence of duct altitude closely follows the boundary layer altitude. Diurnal variation of duct altitude is maximum during postmonsoon followed by winter, monsoon, and minimum in premonsoon. However, duct strength is maximum during winter followed by premonsoon, postmonsoon, and minimum in monsoon. Duct thickness is found to be varying between 0.4 km and 1 km diurnally with the highest thickness during the winter season. Strong diurnal and seasonal variation in the percentage occurrence of the ducts was found with the highest percentage of ducts observed during winter (77%) followed by postmonsoon (51%), premonsoon (44%), and monsoon (10%). All the characteristics of ducts during all the seasons are maximum at 14 LT due to the high solar irradiance over Gadanki from 11 to 17 LT. The minimum frequency being trapped has been investigated and found that wave trapping occurs for the radars with frequencies 56-438 MHz over this station.

  10. Observer variation for radiography, computed tomography, and magnetic resonance imaging of occult hip fractures

    Energy Technology Data Exchange (ETDEWEB)

    Collin, David; Dunker, Dennis; Goethlin, Jan H (Dept. of Radiology, Sahlgrenska Univ. Hospital, Moelndal (Sweden)), email: david.collin@vgregion.se; Geijer, Mats (Center for Medical Imaging and Physiology, Skaane Univ. Hospital, Lund Univ., Lund (Sweden))

    2011-10-15

    Background Conventional radiography is insufficient for diagnosis in a small but not unimportant number of hip fractures, and secondary imaging with computed tomography (CT) or magnetic resonance imaging (MRI) is warranted. There are no convincing observer variation studies performed for conventional radiography or CT in occult fractures, and no large materials for MRI. Purpose To assess observer variation in radiography, CT and MRI of suspected occult, non-displaced hip fractures, and to evaluate to what extent observer experience or patient age may influence observer performance. Material and Methods A total of 375 patients after hip trauma where radiography was followed by CT or MRI to evaluate a suspected occult hip fracture were collected retrospectively from two imaging centers. After scoring by three observers with varying degrees of radiologic experience, observer variation was assessed by using linear weighted kappa statistics. Results For radiography, agreements between the three observers were moderate to substantial for intra capsular fractures, with kappa values in the ranges of 0.56-0.66. Kappa values were substantial for extracapsular fractures, in the ranges of 0.69-0.72. With increasing professional experience, fewer fractures were classified as equivocal at radiography. For CT and MRI, observer agreements were similar and almost perfect, with kappa values in the ranges of 0.85-0.97 and 0.93-0.97. Conclusion There were almost perfect observer agreements for CT and MRI in diagnosing non-displaced, occult hip fractures. Observer agreements for radiography were moderate to substantial, and observer experience influenced agreement only at radiography

  11. Observer variation for radiography, computed tomography, and magnetic resonance imaging of occult hip fractures

    International Nuclear Information System (INIS)

    Background Conventional radiography is insufficient for diagnosis in a small but not unimportant number of hip fractures, and secondary imaging with computed tomography (CT) or magnetic resonance imaging (MRI) is warranted. There are no convincing observer variation studies performed for conventional radiography or CT in occult fractures, and no large materials for MRI. Purpose To assess observer variation in radiography, CT and MRI of suspected occult, non-displaced hip fractures, and to evaluate to what extent observer experience or patient age may influence observer performance. Material and Methods A total of 375 patients after hip trauma where radiography was followed by CT or MRI to evaluate a suspected occult hip fracture were collected retrospectively from two imaging centers. After scoring by three observers with varying degrees of radiologic experience, observer variation was assessed by using linear weighted kappa statistics. Results For radiography, agreements between the three observers were moderate to substantial for intra capsular fractures, with kappa values in the ranges of 0.56-0.66. Kappa values were substantial for extracapsular fractures, in the ranges of 0.69-0.72. With increasing professional experience, fewer fractures were classified as equivocal at radiography. For CT and MRI, observer agreements were similar and almost perfect, with kappa values in the ranges of 0.85-0.97 and 0.93-0.97. Conclusion There were almost perfect observer agreements for CT and MRI in diagnosing non-displaced, occult hip fractures. Observer agreements for radiography were moderate to substantial, and observer experience influenced agreement only at radiography

  12. Chemical cycling and deposition of atmospheric mercury: Global constraints from observations

    Science.gov (United States)

    Selin, Noelle E.; Jacob, Daniel J.; Park, Rokjin J.; Yantosca, Robert M.; Strode, Sarah; Jaeglé, Lyatt; Jaffe, Daniel

    2007-01-01

    We use a global 3-D model of atmospheric mercury (GEOS-Chem) to interpret worldwide observations of total gaseous mercury (TGM) and reactive gaseous mercury (RGM) in terms of the constraints they provide on the chemical cycling and deposition of mercury. Our simulation including a global mercury source of 7000 Mg yr-1 and a TGM lifetime of 0.8 years reproduces the magnitude and large-scale variability of TGM observations at land sites. However, it cannot capture observations of high TGM from ship cruises, implying a problem either in the measurements or in our fundamental understanding of mercury sources. Observed TGM seasonal variation at northern midlatitudes is consistent with a photochemical oxidation for Hg(0) partly balanced by photochemical reduction of Hg(II). Observations of increasing RGM with altitude imply a long lifetime of Hg(II) in the free troposphere. We find in the model that Hg(II) dominates over Hg(0) in the upper troposphere and stratosphere and that subsidence is the principal source of Hg(II) at remote surface sites. RGM observations at Okinawa Island (Japan) show large diurnal variability implying fast deposition, which we propose is due to RGM uptake by sea-salt aerosols. Observed mercury wet deposition fluxes in the United States show a maximum in the southeast, which we attribute to photochemical oxidation of the global Hg(0) pool. They also show a secondary maximum in the industrial Midwest due to regional emissions that is underestimated in the model, possibly because of excessive dry deposition relative to wet (dry deposition accounts for 68% of total mercury deposition in the United States in the model, but this is sensitive to the assumed phase of Hg(II)). We estimate that North American anthropogenic emissions contribute on average 20% to U.S. mercury deposition.

  13. Daytime ozone and temperature variations in the mesosphere: a comparison between SABER observations and HAMMONIA model

    Directory of Open Access Journals (Sweden)

    S. Dikty

    2010-09-01

    Full Text Available This paper investigates the latest version 1.07 SABER (Sounding of the Atmosphere using Broadband Emission Radiometry tropical ozone from the 1.27 μm as well as from the 9.6 μm retrieval and temperature data with respect to day time variations in the upper mesosphere. The processes involved are compared to day time variations of the three-dimensional general circulation and chemistry model HAMMONIA (Hamburg Model of the Neutral and Ionized Atmosphere. The results show a good qualitative agreement for ozone. The amplitude of daytime variations is in both cases approximately 60% of the daytime mean. During equinox the daytime maximum ozone abundance is for both, the observations and the model, higher than during solstice, especially above 0.01 hPa (approx. 80 km. The influence of tidal signatures either directly in ozone or indirectly via a temperature response above 0.01 hPa can not be fully eliminated. Below 0.01 hPa (photo-chemistry is the main driver for variations. We also use the HAMMONIA output of daytime variation patterns of several other different trace gas species, e.g., water vapor and atomic oxygen, to discuss the daytime pattern in ozone. In contrast to ozone, temperature data show little daytime variations between 65 and 90 km and their amplitudes are on the order of less than 1.5%. In addition, SABER and HAMMONIA temperatures show significant differences above 80 km.

  14. Sources of and variations in tropospheric CO in Central Siberia: Numerical experiments and observations at the Zotino Tall Tower Observatory

    Science.gov (United States)

    Shtabkin, Yu. A.; Moiseenko, K. B.; Skorokhod, A. I.; Vasileva, A. V.; Heimann, M.

    2016-01-01

    Contributions of climatically significant natural and anthropogenic emission sources in northern Eurasia to seasonal carbon monoxide (CO) variations observed at the Zotino Tall Tower Observatory (ZOTTO) in Central Siberia in 2007-2011 have quantitatively been estimated using the GEOS-Chem chemical transport model. It is shown that the formation of a stable continental pollution plume from sources in Western Europe, European Russia and southern Siberia during winter plays an important role in the regional balance of surface CO and allows one to explain 55-80% of the amplitude of the CO annual cycle observed at the ZOTTO station (~70-90 ppbv). During the warm period, the effect of the anthropogenic factor is weakly pronounced, and the background concentration of CO is regulated, first and foremost, by the oxidation of biogenic volatile organic compounds and fire activity in the region.

  15. Atmospheric diurnal and semi-diurnal variations observed with GPS radio occultation soundings

    Directory of Open Access Journals (Sweden)

    A. J. Mannucci

    2009-11-01

    Full Text Available Diurnal and semi-diurnal variations, driven by solar forcing, are two fundamental modes in the Earth's weather and climate system. Radio occultation (RO measurements from the six COSMIC satellites (Constellation Observing System for Meteorology Ionosphere and Climate provide rather uniform global coverage with high vertical resolution, all-weather and diurnal sampling capability. This paper analyzes the diurnal and semi-diurnal variations of both temperature and refractivity from two-year (2007–2008 COSMIC RO measurements in the troposphere and stratosphere. The RO observations reveal both propagating and trapped vertical structures of diurnal and semi-diurnal variations, including transition regions near the tropopause where data with high vertical resolution are critical. In the tropics the diurnal amplitude in refractivity decreases with altitude from a local maximum in the planetary boundary layer and reaches the minimum around 14 km and then further increase amplitude in the stratosphere. The upward propagating component of the migrating diurnal tides in the tropics is clearly captured by the GPS RO measurements, which show a downward progression in phase from upper troposphere to the stratopause with a vertical wavelength of about 25 km. Below 500 hPa (~5.5 km, seasonal variations of the peak diurnal amplitude in the tropics follow the solor forcing change in latitude, while at 30 km the seasonal pattern reverses with the diurnal amplitude peaking at the opposite side of the equator relative to the solar forcing. Polar regions shows large diurnal variations in the stratosphere with strong seasonal variations and the cause(s of these variations require further investigations.

  16. Variation in T-SPOT.TB Spot Interpretation between Independent Observers from Different Laboratories▿

    OpenAIRE

    Franken, Willeke P. J.; Thijsen, Steven; Wolterbeek, Ron; Bouwman, John J. M.; el Bannoudi, Hanane; Kik, Sandra V; van Dissel, Jaap T.; Arend, Sandra M.

    2009-01-01

    T-SPOT.TB is a specific assay for the diagnosis of tuberculosis. The assay needs to be performed with freshly isolated cells, and interpretation requires training. T-SPOT.TB has been used in various clinical-epidemiological settings, but so far no studies have evaluated the effect of interobserver variation in test reading. Our aim was to evaluate variation between different observers in reading T-SPOT.TB results. The study was nested within an ongoing cohort study, in which part of the T-SPO...

  17. Inter-observer variation in ultrasound measurement of the volume and diameter of thyroid nodules

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Young Jun; Baek, Jung Hwan; Hong, Min Ji; Lee, Jeong Hyun [Dept. of Radiology, and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of)

    2015-06-15

    Thyroid nodule measurement using ultrasonography (US) is widely performed in various clinical scenarios. The purpose of this study was to evaluate inter-observer variation in US measurement of the volume and maximum diameter of thyroid nodules. This retrospective study included 73 consecutive patients with 85 well-defined thyroid nodules greater than 1 cm in their maximum diameter. US examinations were independently performed by using standardized measurement methods, conducted by two clinically experienced thyroid radiologists. The maximum nodule diameter and nodule volume, calculated from nodule diameters using the ellipsoid formula, were obtained by each reader. Inter-observer variations in volume and maximum diameter were determined using 95% Bland-Altman limits of agreement. The degree of inter-observer variations in volumes and the maximum diameters were compared using the Student's t test, between nodules < 2 cm in maximum diameter and those with > or = 2 cm. The mean inter-observer difference in measuring the nodule volume was -1.6%, in terms of percentage of the nodule volume, and the 95% limit of agreement was +/- 13.1%. For maximum nodule diameter, the mean inter-observer difference was -0.6%, in terms of percentage of the nodule diameter, and the 95% limit of agreement was +/- 7.3%. Inter-observer variation in volume was greater in nodules of < 2 cm in maximum diameter, compared to the larger nodules (p = 0.035). However, no statistically significant difference was noted between the two groups regarding maximum nodule diameters (p = 0.511). Any differences smaller than 13.1% and 7.3% in volume and maximum diameter, respectively, measured by using US for well-defined thyroid nodules of > 1 cm should not be considered as a real change in size.

  18. Observer variation in grading sacroiliac radiographs in HLA-B27 positive individuals

    Energy Technology Data Exchange (ETDEWEB)

    Hollingsworth, P.N.; Cheah, P.S.; Dawkins, R.L.; Owen, E.T.; Calin, A.; Wood, P.H.N. (Royal Perth Hospital (Australia))

    1983-04-01

    This study attempts to reconcile the apparent differences in the reported frequency of ankylosing spondylitis and radiological sacroilitis in HLA-B27 positive individuals. Pelvic radiographs from 125 Busselton subjects were mixed with 81 other films selected to illustrate the possible range of sacroiliac changes and were graded by observers who were involved in 2 of the conflicting studies and by a 3rd independent observer. Concordance was high for advanced bilateral disease but not for unilateral and milder changes. Variation between observers and the interpretation of sacroiliac radiographs is sufficiently large to account for much of the disagreement between frequency estimates.

  19. Periodic variations of oxygen EUV dayglow in the upper atmosphere of Venus: Hisaki/EXCEED observations

    Science.gov (United States)

    Masunaga, K.; Seki, K.; Terada, N.; Tsuchiya, F.; Kimura, T.; Yoshioka, K.; Murakami, G.; Yamazaki, A.; Kagitani, M.; Tao, C.; Fedorov, A.; Futaana, Y.; Zhang, T. L.; Shiota, D.; Leblanc, F.; Chaufray, J.-Y.; Yoshikawa, I.

    2015-12-01

    Using the Extreme Ultraviolet Spectroscope for Exospheric Dynamics (EXCEED) aboard Hisaki and the Solar Extreme Ultraviolet Monitor on the Solar and Heliospheric Observatory, we investigate variations of the extreme ultraviolet (EUV) dayglow brightness for OII 83.4 nm, OI 130.4 nm, and OI 135.6 nm in the Venusian upper atmosphere observed in March-April (period 1), April-May (period 2), and June-July (period 3) in 2014. The result shows that characteristic periodicities exist in the dayglow variations other than the ~27 day solar rotational effect of the solar EUV flux: 1.8, 2.8, 3.1, 4.5, and 9.9 day in period 1; 1.1 day in period 2; and 1.0 and 11 day in period 3. Many of these periodicities are consistent with previous observations and theory. We suggest these periodicities are related to density oscillations of oxygen atoms or photoelectrons in the thermosphere. The cause of these periodicities is still uncertain, but planetary-scale waves and/or gravity waves propagating from the middle atmosphere, and/or minor periodic variations of the solar EUV radiation flux may play a role. Effects of the solar wind parameters (velocity, dynamic pressure, and interplanetary magnetic field's intensity) on the dayglow variations are also investigated using the Analyser of Space Plasma and Energetic Atoms (ASPERA-4) and magnetometer aboard Venus Express. Although clear correlation with the dayglow variations is not found, their minor periodicities are similar to the dayglow periodicities. Contribution of the solar wind to the dayglow remains still unknown, but the solar wind parameters might affect the dayglow variations.

  20. Nitrogen and Oxygen Abundance Variations in the Outer Ejecta of Eta Carinae: Evidence for Recent Chemical Enrichment

    CERN Document Server

    Smith, N; Smith, Nathan; Morse, Jon A.

    2004-01-01

    We present optical spectra of the ionized `Outer Ejecta' of Eta Carinae that reveal differences in chemical composition at various positions. In particular, young condensations just outside the dusty Homunculus Nebula show strong nitrogen lines and little or no oxygen -- but farther away, nitrogen lines weaken and oxygen lines become stronger. The observed variations in the apparent N/O ratio may signify either that the various blobs were ejected with different abundances, or more likely, that the more distant condensations are interacting with normal-composition material. The second hypothesis is supported by various other clues involving kinematics and X-ray emission, and would suggest that Eta Car is enveloped in a ``cocoon'' deposited by previous stellar-wind mass loss. In particular, all emission features where we detect strong oxygen lines are coincident with or outside the soft X-ray shell. In either case, the observed abundance variations suggest that Eta Car's ejection of nitrogen-rich material is a ...

  1. High Frequency Variations of Earth Rotation Parameters from GPS and GLONASS Observations

    Directory of Open Access Journals (Sweden)

    Erhu Wei

    2015-01-01

    Full Text Available The Earth’s rotation undergoes changes with the influence of geophysical factors, such as Earth’s surface fluid mass redistribution of the atmosphere, ocean and hydrology. However, variations of Earth Rotation Parameters (ERP are still not well understood, particularly the short-period variations (e.g., diurnal and semi-diurnal variations and their causes. In this paper, the hourly time series of Earth Rotation Parameters are estimated using Global Positioning System (GPS, Global Navigation Satellite System (GLONASS, and combining GPS and GLONASS data collected from nearly 80 sites from 1 November 2012 to 10 April 2014. These new observations with combining different satellite systems can help to decorrelate orbit biases and ERP, which improve estimation of ERP. The high frequency variations of ERP are analyzed using a de-trending method. The maximum of total diurnal and semidiurnal variations are within one milli-arcseconds (mas in Polar Motion (PM and 0.5 milli-seconds (ms in UT1-UTC. The semidiurnal and diurnal variations are mainly related to the ocean tides. Furthermore, the impacts of satellite orbit and time interval used to determinate ERP on the amplitudes of tidal terms are analyzed. We obtain some small terms that are not described in the ocean tide model of the IERS Conventions 2010, which may be caused by the strategies and models we used or the signal noises as well as artifacts. In addition, there are also small differences on the amplitudes between our results and IERS convention. This might be a result of other geophysical excitations, such as the high-frequency variations in atmospheric angular momentum (AAM and hydrological angular momentum (HAM, which needs more detailed analysis with more geophysical data in the future.

  2. Interstellar extinction curve variations towards the inner Milky Way: a challenge to observational cosmology

    Science.gov (United States)

    Nataf, David M.; Gonzalez, Oscar A.; Casagrande, Luca; Zasowski, Gail; Wegg, Christopher; Wolf, Christian; Kunder, Andrea; Alonso-Garcia, Javier; Minniti, Dante; Rejkuba, Marina; Saito, Roberto K.; Valenti, Elena; Zoccali, Manuela; Poleski, Radosław; Pietrzyński, Grzegorz; Skowron, Jan; Soszyński, Igor; Szymański, Michał K.; Udalski, Andrzej; Ulaczyk, Krzysztof; Wyrzykowski, Łukasz

    2016-03-01

    We investigate interstellar extinction curve variations towards ˜4 deg2 of the inner Milky Way in VIJKs photometry from the OGLE-III (third phase of the Optical Gravitational Lensing Experiment) and VVV (VISTA Variables in the Via Lactea) surveys, with supporting evidence from diffuse interstellar bands and F435W, F625W photometry. We obtain independent measurements towards ˜2000 sightlines of AI, E(V - I), E(I - J) and E(J - Ks), with median precision and accuracy of 2 per cent. We find that the variations in the extinction ratios AI/E(V - I), E(I - J)/E(V - I) and E(J - Ks)/E(V - I) are large (exceeding 20 per cent), significant and positively correlated, as expected. However, both the mean values and the trends in these extinction ratios are drastically shifted from the predictions of Cardelli and Fitzpatrick, regardless of how RV is varied. Furthermore, we demonstrate that variations in the shape of the extinction curve have at least two degrees of freedom, and not one (e.g. RV), which we confirm with a principal component analysis. We derive a median value of = 13.44, which is ˜60 per cent higher than the `standard' value. We show that the Wesenheit magnitude WI = I - 1.61(I - J) is relatively impervious to extinction curve variations. Given that these extinction curves are linchpins of observational cosmology, and that it is generally assumed that RV variations correctly capture variations in the extinction curve, we argue that systematic errors in the distance ladder from studies of Type Ia supernovae and Cepheids may have been underestimated. Moreover, the reddening maps from the Planck experiment are shown to systematically overestimate dust extinction by ˜100 per cent and lack sensitivity to extinction curve variations.

  3. Daytime ozone and temperature variations in the mesosphere: A comparison between SABER observations and HAMMONIA model

    Energy Technology Data Exchange (ETDEWEB)

    Dikty, Sebastian; Weber, Mark; Savigny, Christian von [Institute of Environmental Physics, Bremen (Germany); Schmidt, Hauke [Max Planck Institute for Meteorology, Hamburg (Germany); Mlynczak, Martin [Langley Research Center, NASA (United States)

    2010-07-01

    The scope of this paper is to investigate the latest version 1.07 SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) tropical ozone and temperature data with respect to daytime variations in the upper mesosphere. For a better understanding of the processes involved we compare these daytime variations to the output of the three-dimensional general circulation and chemistry model HAMMONIA (Hamburg Model of the Neutral and Ionized Atmosphere). The results show good agreement for ozone. The amplitude of daytime variations is in both cases approximately 60 % of the daytime mean. During equinox the daytime maximum ozone abundance is for both, the observations and the model, higher than during solstice, especially above 80 km. We also use the HAMMONIA output of daytime variation patterns of several other different trace gas species, e.g., water vapor and atomic oxygen, to discuss the daytime pattern in ozone. In contrast to ozone, temperature data show little daytime variations between 65 and 90 km and their amplitudes are on the order of less than 1.5 %. In addition, SABER and HAMMONIA temperatures show significant differences above 80 km.

  4. Daytime ozone and temperature variations in the mesosphere: a comparison between SABER observations and HAMMONIA model

    Directory of Open Access Journals (Sweden)

    S. Dikty

    2010-01-01

    Full Text Available The scope of this paper is to investigate the latest version 1.07 SABER (Sounding of the Atmosphere using Broadband Emission Radiometry tropical ozone from the 1.27 μm as well as from the 9.6 μm retrieval and temperature data with respect to daytime variations in the upper mesosphere. For a better understanding of the processes involved we compare these daytime variations to the output of the three-dimensional general circulation and chemistry model HAMMONIA (Hamburg Model of the Neutral and Ionized Atmosphere. The results show good agreement for ozone. The amplitude of daytime variations is in both cases approximately 60% of the daytime mean. During equinox the daytime maximum ozone abundance is for both, the observations and the model, higher than during solstice, especially above 80 km. We also use the HAMMONIA output of daytime variation patterns of several other different trace gas species, e.g., water vapor and atomic oxygen, to discuss the daytime pattern in ozone. In contrast to ozone, temperature data show little daytime variations between 65 and 90 km and their amplitudes are on the order of less than 1.5%. In addition, SABER and HAMMONIA temperatures show significant differences above 80 km.

  5. ERP-Variations on Time Scales Between Hours and Months Derived From GNSS Observations

    Science.gov (United States)

    Weber, R.; Englich, S.; Mendes Cerveira, P.

    2007-05-01

    Current observations gained by the space geodetic techniques, especially VLBI, GPS and SLR, allow for the determination of Earth Rotation Parameters (ERPs - polar motion, UT1/LOD) with unprecedented accuracy and temporal resolution. This presentation focuses on contributions to the ERP recovery provided by satellite navigation systems (primarily GPS). The IGS (International GNSS Service), for example, currently provides daily polar motion with an accuracy of less than 0.1mas and LOD estimates with an accuracy of a few microseconds. To study more rapid variations in polar motion and LOD we established in a first step a high resolution (hourly resolution) ERP-time series from GPS observation data of the IGS network covering the year 2005. The calculations were carried out by means of the Bernese GPS Software V5.0 considering observations from a subset of 113 fairly stable stations out of the IGS05 reference frame sites. From these ERP time series the amplitudes of the major diurnal and semidiurnal variations caused by ocean tides are estimated. After correcting the series for ocean tides the remaining geodetic observed excitation is compared with variations of atmospheric excitation (AAM). To study the sensitivity of the estimates with respect to the applied mapping function we applied both the widely used NMF (Niell Mapping Function) and the VMF1 (Vienna Mapping Function 1). In addition, based on computations covering two months in 2005, the potential improvement due to the use of additional GLONASS data will be discussed.

  6. THERMAL AND CHEMICAL EVOLUTIONS OF GALAXY CLUSTERS OBSERVED WITH SUZAKU

    Directory of Open Access Journals (Sweden)

    Kosuke Sato

    2013-12-01

    Full Text Available We studied the properties of the intracluster medium (ICM of galaxy clusters to outer regions observed with Suzaku. The observed temperature dropped by about ~30% from the central region to the virial radius of the clusters. The derived entropy profile agreed with the expectation from simulations within r500, while the entropy profile in r > r500 indicated a flatter slope than the simulations. This would suggest that the cluster outskirts were out of hydrostatic equilibrium. As for the metallicity, we studied the metal abundances from O to Fe up to ~0.5 times the virial radius of galaxy groups and clusters. Comparing the results with supernova nucleosynthesis models, the number ratio of type II to Ia supernovae is estimated to be ~3.5. We also calculated not only Fe, but also O and Mg mass-to-light ratios (MLRs with K-band luminosity. The MLRs in the clusters had a similar feature.

  7. Theoretical constraints of physical and chemical properties of hydrothermal fluids on variations in chemolithotrophic microbial communities in seafloor hydrothermal systems

    Science.gov (United States)

    Nakamura, Kentaro; Takai, Ken

    2014-12-01

    In the past few decades, chemosynthetic ecosystems at deep-sea hydrothermal vents have received attention as plausible analogues to the early ecosystems of Earth, as well as to extraterrestrial ecosystems. These ecosystems are sustained by chemical energy obtained from inorganic redox substances (e.g., H2S, CO2, H2, CH4, and O2) in hydrothermal fluids and ambient seawater. The chemical and isotope compositions of the hydrothermal fluid are, in turn, controlled by subseafloor physical and chemical processes, including fluid-rock interactions, phase separation and partitioning of fluids, and precipitation of minerals. We hypothesized that specific physicochemical principles describe the linkages among the living ecosystems, hydrothermal fluids, and geological background in deep-sea hydrothermal systems. We estimated the metabolic energy potentially available for productivity by chemolithotrophic microorganisms at various hydrothermal vent fields. We used a geochemical model based on hydrothermal fluid chemistry data compiled from 89 globally distributed hydrothermal vent sites. The model estimates were compared to the observed variability in extant microbial communities in seafloor hydrothermal environments. Our calculations clearly show that representative chemolithotrophic metabolisms (e.g., thiotrophic, hydrogenotrophic, and methanotrophic) respond differently to geological and geochemical variations in the hydrothermal systems. Nearly all of the deep-sea hydrothermal systems provide abundant energy for organisms with aerobic thiotrophic metabolisms; observed variations in the H2S concentrations among the hydrothermal fluids had little effect on the energetics of thiotrophic metabolism. Thus, these organisms form the base of the chemosynthetic microbial community in global deep-sea hydrothermal environments. In contrast, variations in H2 concentrations in hydrothermal fluids significantly impact organisms with aerobic and anaerobic hydrogenotrophic metabolisms

  8. Decreased 3D observer variation with matched CT-MRI, for target delineation in Nasopharynx cancer

    International Nuclear Information System (INIS)

    To determine the variation in target delineation of nasopharyngeal carcinoma and the impact of measures to minimize this variation. For ten nasopharyngeal cancer patients, ten observers each delineated the Clinical Target Volume (CTV) and the CTV elective. After 3D analysis of the delineated volumes, a second delineation was performed. This implied improved delineation instructions, a combined delineation on CT and co-registered MRI, forced use of sagittal reconstructions, and an on-line anatomical atlas. Both for the CTV and the CTV elective delineations, the 3D SD decreased from Phase 1 to Phase 2, from 4.4 to 3.3 mm for the CTV and from 5.9 to 4.9 mm for the elective. There was an increase agreement, where the observers intended to delineate the same structure, from 36 to 64 surface % (p = 0.003) for the CTV and from 17 to 59% (p = 0.004) for the elective. The largest variations were at the caudal border of the delineations but these were smaller when an observer utilized the sagittal window. Hence, the use of sagittal side windows was enforced in the second phase and resulted in a decreased standard deviation for this area from 7.7 to 3.3 mm (p = 0.001) for the CTV and 7.9 to 5.6 mm (p = 0.03) for the CTV elective. Attempts to decrease the variation need to be tailored to the specific causes of the variation. Use of delineation instructions multimodality imaging, the use of sagittal windows and an on-line atlas result in a higher agreement on the intended target

  9. Seasonal and diurnal variations in AMPERE observations of the Birkeland currents compared to modeled results

    Science.gov (United States)

    Coxon, J. C.; Milan, S. E.; Carter, J. A.; Clausen, L. B. N.; Anderson, B. J.; Korth, H.

    2016-05-01

    We reduce measurements made by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) to give the total Birkeland (field-aligned) current flowing in both hemispheres in monthly and hourly bins. We analyze these totals using 6 years of data (2010-2015) to examine solar zenith angle-driven variations in the total Birkeland current flowing in both hemispheres, simultaneously, for the first time. A diurnal variation is identified in the total Birkeland current flowing, consistent with variations in the solar zenith angle. A seasonal variation is also identified, with more current flowing in the Northern (Southern) Hemisphere during Bartels rotations in northern (southern) summer. For months close to equinox, more current is found to flow in the Northern Hemisphere, contrary to our expectations. We also conduct the first test of the Milan (2013) model for estimating Birkeland current magnitudes, with modifications made to account for solar contributions to ionospheric conductance based on the observed variation of the Birkeland currents with season and time of day. The modified model, using the value of ΦD averaged by Bartels rotation (scaled by 1.7), is found to agree with the observed AMPERE currents, with a correlation of 0.87 in the Northern Hemisphere and 0.86 in the Southern Hemisphere. The improvement over the correlation with dayside reconnection rate is demonstrated to be a significant improvement to the model. The correlation of the residuals is found to be consistent with more current flowing in the Northern Hemisphere. This new observation of systematically larger current flowing in the Northern Hemisphere is discussed in the context of previous results which suggest that the Northern Hemisphere may react more strongly to dayside reconnection than the Southern Hemisphere.

  10. Decreased 3D observer variation with matched CT-MRI, for target delineation in Nasopharynx cancer

    Directory of Open Access Journals (Sweden)

    Kaanders Johannes HAM

    2010-03-01

    Full Text Available Abstract Purpose To determine the variation in target delineation of nasopharyngeal carcinoma and the impact of measures to minimize this variation. Materials and methods For ten nasopharyngeal cancer patients, ten observers each delineated the Clinical Target Volume (CTV and the CTV elective. After 3D analysis of the delineated volumes, a second delineation was performed. This implied improved delineation instructions, a combined delineation on CT and co-registered MRI, forced use of sagittal reconstructions, and an on-line anatomical atlas. Results Both for the CTV and the CTV elective delineations, the 3D SD decreased from Phase 1 to Phase 2, from 4.4 to 3.3 mm for the CTV and from 5.9 to 4.9 mm for the elective. There was an increase agreement, where the observers intended to delineate the same structure, from 36 to 64 surface % (p = 0.003 for the CTV and from 17 to 59% (p = 0.004 for the elective. The largest variations were at the caudal border of the delineations but these were smaller when an observer utilized the sagittal window. Hence, the use of sagittal side windows was enforced in the second phase and resulted in a decreased standard deviation for this area from 7.7 to 3.3 mm (p = 0.001 for the CTV and 7.9 to 5.6 mm (p = 0.03 for the CTV elective. Discussion Attempts to decrease the variation need to be tailored to the specific causes of the variation. Use of delineation instructions multimodality imaging, the use of sagittal windows and an on-line atlas result in a higher agreement on the intended target.

  11. Singular Vector Based Targeted Observations of Atmospheric Chemical Compounds

    OpenAIRE

    Goris, Nadine

    2010-01-01

    Measurements of the earth's environment provide only sparse snapshots of the state of the system due to their insufficient temporal and spatial density. In face of these limitations, the measurement configurations need to be optimized to get a best possible state estimate. One possibility to optimize the state estimate is provided by targeted observations of sensitive system states, where measurements are of great value for forecast improvements. In the recent years, numerical weather predict...

  12. Chemical telemetry of OH observed to measure interstellar magnetic fields

    CERN Document Server

    Viti, S; Myers, P C

    2005-01-01

    We present models for the chemistry in gas moving towards the ionization front of an HII region. When it is far from the ionization front, the gas is highly depleted of elements more massive than helium. However, as it approaches the ionization front, ices are destroyed and species formed on the grain surfaces are injected into the gas phase. Photodissociation removes gas phase molecular species as the gas flows towards the ionization front. We identify models for which the OH column densities are comparable to those measured in observations undertaken to study the magnetic fields in star forming regions and give results for the column densities of other species that should be abundant if the observed OH arises through a combination of the liberation of H2O from surfaces and photodissociation. They include CH3OH, H2CO, and H2S. Observations of these other species may help establish the nature of the OH spatial distribution in the clouds, which is important for the interpretation of the magnetic field results.

  13. Assimilation of geomagnetic observations in dynamical models of the secular variation

    International Nuclear Information System (INIS)

    Complete text of publication follows. Satellite data contribute to a better description of the secular variation of the main geomagnetic field. To make the best use of that (and upcoming) wealth of data, we consider the possibility to resort to data assimilation, as now routinely used in the fields of meteorology and oceanography. Geomagnetic data assimilation aims at identifying the physics of the Earth's core responsible for the secular variation recorded by satellites and in long-lived, ground observatories. Data assimilation should yield a more accurate forecast of the secular variation, and enable the reanalysis of historical observations. The physics at the heart of our assimilation scheme is based on the assumption that the dynamics responsible for the fast (i.e. interannual) variations of the main magnetic field is quasi-geostrophic. In addition, we describe similarly the magnetic field, in the core interior, using a magnetic flux function, whose dynamics is also two-dimensional. In this presentation, we will focus on the methodological aspects of our assimilation scheme. In particular, we illustrate how the accumulation of successive observations can be used to construct dynamically consistent, time-dependent maps of the magnetic field inside the core.

  14. Surface-enhanced Raman scattering (SERS) revealing chemical variation during biofilm formation: from initial attachment to mature biofilm

    OpenAIRE

    Chao, Yuanqing; Tong ZHANG

    2012-01-01

    Surface-enhanced Raman scattering (SERS) has recently been proved to be a promising technique for characterizing the chemical composition of the biofilm matrix. In the present study, to fully understand the chemical variations during biofilm formation, SERS based on silver colloidal nanoparticles was applied to evaluate the chemical components in the matrix of biofilm at different growth phases, including initial attached bacteria, colonies, and mature biofilm. Meanwhile, atomic force microsc...

  15. Inter-observer variation of diagnosis of Alzheimer's disease by SPECT

    International Nuclear Information System (INIS)

    SPECT shows characteristic distribution in Alzheimer's disease. The purpose of this study is to define inter-observer variations in the diagnosis of Alzheimer's disease. Fifty-seven patients, included 19 Alzheimer's disease were collected from four institutions. Five-graded score was used to interprete SPECT in 18 regions. Ten nuclear medicine physicians interpreted SPECT referred with MMSE and clinical information. Among 57 cases 19 Alzheimer's disease were selected in this study. Statistics were performed between SPECT score and MMSE score. In conclusion, inter-observer variation is present in SPECT interpretation. There was a good correlation SPECT and MMSE with proper brain SPECT physicians. They are superior to in the interpretation not only resident, but other specialists. Education in the interpretation of brain SPECT looks important. (author)

  16. Monitoring RXTE Observations of Markarian 348 the origin of the column density variations

    CERN Document Server

    Akylas, A; Griffiths, R G; Papadakis, I E; Mastichiadis, A; Warwick, R S; Nandra, K; Smith, D A

    2002-01-01

    We analyze 37 RXTE observations of the type 2 Seyfert galaxy Mrk348 obtained during a period of 14 months. We confirm the spectral variability previous reported by Smith et al., in the sense that thecolumn density decreases by a factor of ~3 as the count rate increases. Column density variations could possibly originate either due to the random drift of clouds within the absorption screen, or due to photoionization processes. Our modeling of the observed variations implies that the first scenario is more likely. These clouds should lie in a distance of >2 light years from the source, having a diameter of a few light days and a density of >10^7 cm^(-3), hence probably residing outside the Broad Line Region.

  17. Observation of contrast variations of a copper (Ⅱ) complex by scanning tunneling microscopy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    This report presents experimental observations of dramatic variations in STM images of bis [1,3- di(p-n-tetradecyloxyphenyl)propane-1,3-dionato] copper(Ⅱ) (abbreviated to C14O-Cu) physisorbed on HOPG as the bias voltage is changed. Several representative image patterns were obtained for the rich changes of the internal contrast of the molecule. Submolecular features of the molecular cores and the interdigitated alkyl parts are clearly visible.

  18. Physico-chemical properties and cytotoxic effects of sugar-based surfactants: Impact of structural variations.

    Science.gov (United States)

    Lu, Biao; Vayssade, Muriel; Miao, Yong; Chagnault, Vincent; Grand, Eric; Wadouachi, Anne; Postel, Denis; Drelich, Audrey; Egles, Christophe; Pezron, Isabelle

    2016-09-01

    Surfactants derived from the biorefinery process can present interesting surface-active properties, low cytotoxicity, high biocompatibility and biodegradability. They are therefore considered as potential sustainable substitutes to currently used petroleum-based surfactants. To better understand and anticipate their performances, structure-property relationships need to be carefully investigated. For this reason, we applied a multidisciplinary approach to systematically explore the effect of subtle structural variations on both physico-chemical properties and biological effects. Four sugar-based surfactants, each with an eight carbon alkyl chain bound to a glucose or maltose head group by an amide linkage, were synthesized and evaluated together along with two commercially available standard surfactants. Physico-chemical properties including solubility, Krafft point, surface-tension lowering and critical micellar concentration (CMC) in water and biological medium were explored. Cytotoxicity evaluation by measuring proliferation index and metabolic activity against dermal fibroblasts showed that all surfactants studied may induce cell death at low concentrations (below their CMC). Results revealed significant differences in both physico-chemical properties and cytotoxic effects depending on molecule structural features, such as the position of the linkage on the sugar head-group, or the orientation of the amide linkage. Furthermore, the cytotoxic response increased with the reduction of surfactant CMC. This study underscores the relevance of a methodical and multidisciplinary approach that enables the consideration of surfactant solution properties when applied to biological materials. Overall, our results will contribute to a better understanding of the concomitant impact of surfactant structure at physico-chemical and biological levels. PMID:27137806

  19. VLA observations of rapid 6 cm flux variations in alpha Ori

    Science.gov (United States)

    Bookbinder, J. A.; Stencel, R. E.; Drake, S. A.; Simon, T.; Linsky, J. L.; Florkowski, D.

    1987-01-01

    The red supergiant star alpha Ori was monitored with the Very Large Array (VLA). Thirteen observations at 6 cm show stochastic variations, at the 30 to 40 percent level, with no long term trend. All data was clipped and tapered in AIPS to minimize differences between VLA arrays. The calibration source varied by less than 10 percent over the same interval. The VLA observations of alpha Ori were continued, as well as alpha Her and alpha Sco, at both 2 and 6 cm, to confirm this result and search for long term trends. The stochastic 6 cm flux behavior, with 30 to 40 percent changes on all timescales from the shortest interval of 10 days to the longest, seems at odds with the 400 day periodic variations in U-band photometry and Mg II UV fluxes reported by Dupree, et al. The observed 6 cm flux was 25 percent below the 6 cm flux reported earlier this decade. Several models for the outer atmosphere of alpha Ori place the 6 cm optical depth unity location at several stellar radii above the optical photosphere. The rapid, stochastic variations reported are difficult to reconcile with almost any global process, such as pulsation, Alfven waves or periastron passage.

  20. Variational assimilation of meteorological observations in the lower atmosphere: A tutorial on how it works

    Science.gov (United States)

    Schlatter, T. W.

    2000-08-01

    Data assimilation combines atmospheric measurements with knowledge of atmospheric behavior as codified in computer models, thus producing a ``best'' estimate of current conditions that is consistent with both information sources. The four major challenges in data assimilation are: (1) to generate an initial state for a computer forecast that has the same mass-wind balance as the assimilating model, (2) to deal with the common problem of highly non-uniform distribution of observations, (3) to exploit the value of proxy observations (of parameters that are not carried explicitly in the model), and (4) to determine the statistical error properties of observing systems and numerical model alike so as to give each information source the proper weight. Variational data assimilation is practiced at major meteorological centers around the world. It is based upon multivariate linear regression, dating back to Gauss, and variational calculus. At the heart of the method is the minimization of a cost function, which guarantees that the analyzed fields will closely resemble both the background field (a short forecast containing a priori information about the atmospheric state) and current observations. The size of the errors in the background and the observations (the latter, arising from measurement and non-representativeness) determine how close the analysis is to each basic source of information. Three-dimensional variational (3DVAR) assimilation provides a logical framework for incorporating the error information (in the form of variances and spatial covariances) and deals directly with the problem of proxy observations. 4DVAR assimilation is an extension of 3DVAR assimilation that includes the time dimension; it attempts to find an evolution of model states that most closely matches observations taken over a time interval measured in hours. Both 3DVAR and, especially, 4DVAR assimilation require very large computing resources. Researchers are trying to find more efficient

  1. Seasonal variation of chemical composition and biomethane production from the brown seaweed Ascophyllum nodosum.

    Science.gov (United States)

    Tabassum, Muhammad Rizwan; Xia, Ao; Murphy, Jerry D

    2016-09-01

    Ascophyllum nodosum, an abundant Irish brown seaweed, shows significant seasonal variation in chemical composition and biogas production. The polyphenol content is shown to be a more important factor in biogas production than ash content. High polyphenol content in summer months adversely affected biogas production; suggesting two potential harvest dates, March and October. A. nodosum harvested in October showed a relatively low level of polyphenols (2% of TS) and ash (23% of volatile solids), and exhibited a specific methane yield of 215LCH4kgVS(-1), which was 44% of theoretical yield. The highest yield per wet weight of 47m(3)CH4t(-1) was achieved in October, which is 2.9 times higher than the lowest value (16m(3)CH4t(-1)), obtained in December. The gross energy yield of A. nodosum based on the optimal biogas production can achieve 116GJha(-1)yr(-1) in October. PMID:27240238

  2. Seasonal variations of tertiary and secondary ozone maxima observed by JEM/SMILES

    Science.gov (United States)

    Mahani, Mona; Sagawa, Hideo; Murata, Isao; Kasaba, Yasumasa; Kasai, Yasuko

    2013-04-01

    We represent seasonal variations of the tertiary and secondary peaks of ozone according to the SMILES (Superconducting sub-Millimeter Limb Emission Sounder) observation. The tertiary ozone maximum is typically known to form around high-latitude winter mesosphere at an altitude of 70 km. The reason would be the decrease of odd-oxygen losses due to the lower concentrations of odd-hydrogen. The secondary ozone peak exists in upper mesosphere lower thermosphere (MLT) (90-105 km) near the location of atomic oxygen maximum density. Although there are still database limitations for night time ozone measurements in the mesosphere - day and night time ozone measurements should be separated because of the strong diurnal variation of ozone in mesospheric region - , SMILES sub-millimeter passive sensor was able to observe the atmosphere during day and night time. SMILES is a highly sensitive radiometer to observe atmospheric compositions located at the Japanese Experiment Module (JEM) on board the International Space Station (ISS) with the latitudinal coverage of 38S to 65N. It successfully measured vertical distributions and diurnal variations of ozone from upper troposphere to MLT region during its operational period October 2009 to April 2010. The precision of SMILES mesospheric ozone is less than 10-30%. We depict monthly latitudinal distributions of the ozone mixing ratio profiles, as well as the seasonal variations of profiles at several latitudes. At northern polar region, the altitudes of the mesospheric ozone maxima are determined at 70 and 90 km for tertiary and secondary peaks respectively. The ozone concentrations of tertiary and secondary ozone layers were shown to vary seasonally around 50%. The ozone minimum is shown below 80 km with the daily means lower than 0.25 ppm. As a near future perspective to expand our understanding of mesospheric ozone, we aim to compare the mesospheric profiles with GOMOS (Global Ozone Monitoring by Occultation of Stars) ozone

  3. THEMIS observations of double-onset substorms and their association with IMF variations

    Directory of Open Access Journals (Sweden)

    C.-C. Cheng

    2011-03-01

    Full Text Available On 16 July 2008, two pairs of consecutive bursts of Pi2 pulsations were recorded simultaneously across the THEMIS ground-based observatory system. Wavelet transformation reveals that for each high-latitude pair, the dominant frequency of the first burst is higher than that of the second. But at low latitudes, the dominant frequency does not change. It is suggested that both pairs result from fast magnetospheric cavity waves with the second burst also containing shear Alfvén waves. INTERMAGNET magnetograms at auroral latitudes showed magnetic variations affected by two recurrent electrojets for each pair. The ground-based magnetometers and those at geostationary orbit sensed magnetic perturbations consistent with the formation of the substorm current wedge. Four consecutive enhancements of energetic electron and ion fluxes detected by the THEMIS probes in the dayside magnetosphere appeared in the later afternoon and then in the early afternoon. The horizontal magnetic variation vectors had vortex patterns similar to those induced by the upward and downward field-aligned currents during substorm times. The hodogram at mid-L stations had a polarization pattern similar to the one induced by the substorm current wedge for each Pi2 burst. The mapping of ground Pi2 onset timing to the interplanetary magnetic field (IMF observations shows that they appear under two cycles of north-to-south and then north variation. CLUSTER 4 in the south lobe observed wave-like magnetic fluctuations, probably driven by near-Earth reconnection, similar to those on the ground. These two observations are consistent with the link of double-onset substorms to magnetotail reconnection externally triggered by IMF variations.

  4. Variation of acoustic cutoff period with height in the solar atmosphere: theory versus observations

    CERN Document Server

    Murawski, K; Konkol, P; Wiśniewska, A

    2016-01-01

    Recently Wi\\'sniewska et al. demonstrated observationally how the acoustic cutoff frequency varies with height in the solar atmosphere including the upper photosphere and the lower and middle chromosphere, and showed that the observational results cannot be accounted for by the existing theoretical formulas for the acoustic cutoff. In order to reproduce the observed variation of the cutoff with atmospheric height, numerical simulations of impulsively generated acoustic waves in the solar atmosphere are performed, and the spectral analysis of temporal wave profiles is used to compute numerically changes of the acoustic cutoff with height. Comparison of the numerical results with the observational data shows good agreement, which clearly indicates that the obtained results may be used to determine the structure of the background solar atmosphere.

  5. TIMED GUVI and SEE Observations of Solar Irradiance Variations and the Terrestrial Airglow Response

    Science.gov (United States)

    Wolven, B.; Paxton, L.; Morrison, D.; Woods, T.

    2004-12-01

    Since the launch of the TIMED mission in 2001, the SEE and GUVI instruments have observed solar radiance changes during numerous solar flares, and measured their short-term impact on the terrestrial airglow, manifested as changes in both resonantly scattered and photoelectron excited emissions. The continuous coverage and higher time resolution of the GUVI airglow observations, in conjunction with the multispectral (5-color) image format, constitute a unique source of information on the time variation of the solar irradiance in different spectral regions. GUVI limb observations provide additional data on heating and composition changes in the thermosphere in response to these energy inputs. We examine changes in the observed airglow between quiet and flare conditions, and attempt to understand the differences between SEE measurements and the radiances inferred from GUVI airglow data.

  6. Solar observations with Rio de Janeiro Danjon astrolabe: diameter variations and its correlations (1998-2000)

    CERN Document Server

    Neto, Eugênio Reis

    2013-01-01

    This work has aimed to analyze the 1998 to 2000 campaign of solar diameter surveying. The employed instrument was a Danjon astrolabe, at the Observat\\'orio Nacional campus, and specially modified for the solar observations. During the time lapse, 10807 independent measurements of the solar diameter were made, Eastwards and Westwards from the local meridian and evenly distributed. An image treatment has been devised to account for the camera dark current and flat field, using IRAF routines. A study of the observational conditions upon the final outcome was made. The mean temperature at the observation is shown as the most influential parameter upon the final result. Next to it also the temperature variation, the Fried's factor, and the standard deviation of the reflected parabola presented a minor and complex degree of influence. The derived corrections are of the order of hundredths of arc seconds, thus being tenfold smaller than the typical error of one observation. The mean semidiameter for the time lapse (...

  7. Surface Freshwater Storage Variations in the Orinoco Floodplains Using Multi-Satellite Observations

    Directory of Open Access Journals (Sweden)

    Frédéric Frappart

    2014-12-01

    Full Text Available Variations in surface water extent and storage are poorly characterized from regional to global scales. In this study, a multi-satellite approach is proposed to estimate the water stored in the floodplains of the Orinoco Basin at a monthly time-scale using remotely-sensed observations of surface water from the Global Inundation Extent Multi-Satellite (GIEMS and stages from Envisat radar altimetry. Surface water storage variations over 2003–2007 exhibit large interannual variability and a strong seasonal signal, peaking during summer, and associated with the flood pulse. The volume of surface water storage in the Orinoco Basin was highly correlated with the river discharge at Ciudad Bolivar (R = 0.95, the closest station to the mouth where discharge was estimated, although discharge lagged one month behind storage. The correlation remained high (R = 0.73 after removing seasonal effects. Mean annual variations in surface water volume represented ~170 km3, contributing to ~45% of the Gravity Recovery and Climate Experiment (GRACE-derived total water storage variations and representing ~13% of the total volume of water that flowed out of the Orinoco Basin to the Atlantic Ocean.

  8. Seasonal variations in physico-chemical characteristics of Tuticorin coastal waters, southeast coast of India

    Science.gov (United States)

    Balakrishnan, S.; Chelladurai, G.; Mohanraj, J.; Poongodi, J.

    2015-11-01

    Physico-chemical parameters were determined along the Vellapatti, Tharuvaikulam and Threspuram coastal waters, southeast coast of India. All the physico-chemical parameters such as sea surface temperature, salinity, pH, total alkalinity, total suspended solids, dissolved oxygen and nutrients like nitrate, nitrite, inorganic phosphate and reactive silicate were studied for a period of 12 months (June 2014-May 2015). Sea surface temperature varied from 26.4 to 29.7 °C. Salinity varied from 26.1 and 36.2 ‰, hydrogen ion concentration ranged between 8.0 and 8.5. Variation in dissolved oxygen content was from 4.125 to 4.963 mg l-1. Total alkalinity ranged from 64 to 99 mg/l. Total suspended solids ranged from 24 to 97 mg/l. Concentrations of nutrients, viz. nitrates (2.047-4.007 μM/l), nitrites (0.215-0.840 μM/l), phosphates (0.167-0.904 µM/l), total phosphorus (1.039-3.479 μM/l), reactive silicates (3.737-8.876 μM/l) ammonia (0.078-0.526 μM/l) and also varied independently.

  9. Chemical evolution of Mg isotopes versus the time variation of the fine structure constant

    International Nuclear Information System (INIS)

    We show that the synthesis of Mg25,26 at the base of the convective envelope in low-metallicity asymptotic giant branch stars can produce the isotopic ratios needed to explain the low-z subset (with z<1.8) of the many-multiplet data from quasar absorption systems without invoking a time variation of the fine structure constant. This is supported by observations of high abundances of the neutron-rich Mg isotopes in metal-poor globular-cluster stars. We conclude that the quasar absorption spectra may be providing interesting information on the nucleosynthetic history of such systems

  10. Stratospheric O3 changes during 2001–2010: the small role of solar flux variations in a chemical transport model

    Directory of Open Access Journals (Sweden)

    S. S. Dhomse

    2013-10-01

    Full Text Available Solar spectral fluxes (or irradiance measured by the SOlar Radiation and Climate Experiment (SORCE show different variability at ultraviolet (UV wavelengths compared to other irradiance measurements and models (e.g. NRL-SSI, SATIRE-S. Some modelling studies have suggested that stratospheric/lower mesospheric O3 changes during solar cycle 23 (1996–2008 can only be reproduced if SORCE solar fluxes are used. We have used a 3-D chemical transport model (CTM, forced by meteorology from the European Centre for Medium-Range Weather Forecasts (ECMWF, to simulate middle atmospheric O3 using three different solar flux data sets (SORCE, NRL-SSI and SATIRE-S. Simulated O3 changes are compared with Microwave Limb Sounder (MLS and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER satellite data. Modelled O3 anomalies from all solar flux data sets show good agreement with the observations, despite the different flux variations. The off-line CTM reproduces these changes through dynamical information contained in the analyses. A notable feature during this period is a robust positive solar signal in the tropical middle stratosphere, which is due to realistic dynamical changes in our simulations. Ozone changes in the lower mesosphere cannot be used to discriminate between solar flux data sets due to large uncertainties and the short time span of the observations. Overall this study suggests that, in a CTM, the UV variations detected by SORCE are not necessary to reproduce observed stratospheric O3 changes during 2001–2010.

  11. IUE observations of phase-dependent variations in WN + O systems

    International Nuclear Information System (INIS)

    IUE observations of six WN + O Wolf-Rayet (W-R) systems are reported. The periodic variations in five of the six systems are shown to result primarily from selective atmospheric eclipses of the O star continuum by the W-R wind. An optical depth distribution of the form tau proportional r-1 is suggested for r ≥ 14 R radius of sun. The presence of the N IV ionization stage out to at least ∼60 R radius of the sun is consistent with the proposed constant ionization structure in WN winds (Willis). Phase-dependent variations in the C IV 1550 absorption components in V444 Cyg, HD 90657, and HD 211853 are interpreted as wind-wind collision effects. 41 references, 4 figures, 4 tables

  12. Diagnosing Land Water Storage Variations in Major Indian River Basins using GRACE observations

    Science.gov (United States)

    Soni, Aarti; Syed, Tajdarul H.

    2015-10-01

    Scarcity of freshwater is one of the most critical resource issue the world is facing today. Due to its finite nature, renewable freshwater reserves are under relentless pressure due to population growth, economic development and rapid industrialization. Assessment of Terrestrial Water Storage (TWS), as an unified measure of freshwater reserve, is vital to understand hydrologic and climatic processes controlling its availability. In this study, TWS variations from Gravity Recovery and Climate Experiment (GRACE) satellites are analyzed in conjuction with multi-platform hydrologic observations for the period of 2003-2012. Here, the primary objective is to quantify and attribute the observed short-term variability of TWS and groundwater storage in the largest river basins of India (Ganga, Godavari, Krishna and Mahanadi). Alongside commendable agreement between TWS variations obtained from GRACE and water balance computation, results highlight some of the important deficiencies between the two. While monthly changes in TWS are highly correlated with precipitation, monthly TWS anomalies reveal a 1-2 month lag in their concurrence. Analysis of groundwater storage estimates demonstrate significant decline in the Ganga basin (- 1.28 ± 0.20 mm/month) but practically no change in the Mahanadi basin. On the contrary, groundwater storage in Godavari and Krishna basins reveal notable increase at the rate of 0.74 ± 0.21 mm/month and 0.97 ± 0.21 mm/month respectively. Subsequently, in order to assess the influence of quasi-periodic, planetary scale, variations in the Earth's climate system, groundwater storage anomalies are evaluated with reference to ENSO variability. Results manifest that in all the basins, with the exception of Ganga, groundwater storage is dominantly influenced by ENSO, with large decrease (increase) during El Niño (La Niña) events. In the Ganga basin, groundwater storage variations refer to possible amalgamation of human intervention and natural climate

  13. Latitudinal variation of thermospheric hydrogen near solstice from AE-D observations

    Science.gov (United States)

    Sanatani, S.; Breig, E. L.

    1988-01-01

    Variations of thermospheric neutral atomic hydrogen with latitude during a solstice season near solar minimum were investigated using data acquired with the polar-orbiting AE-D satellite. Hydrogen concentrations at low latitude were found to be comparable to those found from observations with the AE-E satellite, but were slightly higher than concentrations derived from the 1983 mass spectrometer incoherent scatter atmospheric model. Results confirm the general summer-to-winter density increase, large latitudinal gradients in the summer hemisphere, and the winter enhancement of hydrogen observed in AE-C nighttime measurements. The AE-D data, however, show a small polar depression in hydrogen concentration at high winter latitudes, attributed to atmospheric dynamics following auroral heating. The density gradients observed by AE-D in the summer hemisphere were in sharp contrast to the more constant horizontal daytime profiles reported from OGO-6 and previous AE-C measurements, indicating the possibility of local time effects.

  14. Observing and modeling long-period tidal variations in polar motion

    Science.gov (United States)

    Gross, R. S.; Dickman, S. R.

    2011-10-01

    By exchanging angular momentum with the solid Earth, ocean tides cause the Earth's rotation to change. While hydrodynamic tide models have been used to study the effect of ocean tides on polar motion, it is shown here that none of the published models can fully account for the observed variations. An empirical ocean tide model is therefore determined by fitting periodic terms at the tidal frequencies to polar motion excitation observations spanning 1980.0-2010.4 from which atmospheric and non-tidal oceanic effects were removed. While the empirical ocean tide model does fully account for all of the observed tidal power, tests indicate that the model may not have completely converged. So better models of the effects of ocean tides on polar motion are still needed, both dynamical and empirical.

  15. Observations of perturbations produced by powerful chemical explosions in the ionosphere

    Science.gov (United States)

    Blanc, Elisabeth; Jacobson, Abram R.

    1990-10-01

    Observations by HF ionospheric sounding of disturbances produced by powerful chemical explosions (several KT) are described. These experiments were performed at distances of about 30 to 40 km from the explosion point. Because of the amplification due to the atmospheric density decrease with increasing altitude, the acoustic waves from such explosions are characterized by shock waves features when they reach the ionosphere. The development of the disturbance was studied from the lower E region up to the F2 region by using 8 sounding frequencies. It is shown that a blanketing sporadic E layer undergoes small scale fluctuations and becomes semi-transparent after the passage of the disturbance. Several wave fronts with different properties are followed to the F1 region. In the lower E region, the wave induced stratifications on which the radio waves are partially reflected. The echoes totally reflected in the E region undergo an amplitude modulation with a period of about 2 seconds, persisting about 30 minutes. The variations of the total reflection height and of the Doppler frequency shift are most noticeable in the F1 region. The wave loses its shock wave feature in the F2 region and the disturbance signature is then that of a pseudo-sinusoidal wave with a wave length of several tens of kilometers.

  16. Strato-mesospheric ClO observations by SMILES: error analysis and diurnal variation

    Science.gov (United States)

    Sato, T. O.; Sagawa, H.; Kreyling, D.; Manabe, T.; Ochiai, S.; Kikuchi, K.; Baron, P.; Mendrok, J.; Urban, J.; Murtagh, D.; Yasui, M.; Kasai, Y.

    2012-11-01

    Chlorine monoxide (ClO) is the key species for anthropogenic ozone losses in the middle atmosphere. We observed ClO diurnal variations using the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on the International Space Station, which has a non-sun-synchronous orbit. This includes the first global observations of the ClO diurnal variation from the stratosphere up to the mesosphere. The observation of mesospheric ClO was possible due to 10-20 times better signal-to-noise (S/N) ratio of the spectra than those of past or ongoing microwave/submillimeter-wave limb-emission sounders. We performed a quantitative error analysis for the strato- and mesospheric ClO from the Level-2 research (L2r) product version 2.1.5 taking into account all possible contributions of errors, i.e. errors due to spectrum noise, smoothing, and uncertainties in radiative transfer model and instrument functions. The SMILES L2r v2.1.5 ClO data are useful over the range from 0.01 and 100 hPa with a total error estimate of 10-30 pptv (about 10%) with averaging 100 profiles. The SMILES ClO vertical resolution is 3-5 km and 5-8 km for the stratosphere and mesosphere, respectively. The SMILES observations reproduced the diurnal variation of stratospheric ClO, with peak values at midday, observed previously by the Microwave Limb Sounder on the Upper Atmosphere Research Satellite (UARS/MLS). Mesospheric ClO demonstrated an opposite diurnal behavior, with nighttime values being larger than daytime values. A ClO enhancement of about 100 pptv was observed at 0.02 to 0.01 hPa (about 70-80 km) for 50° N-65° N from January-February 2010. The performance of SMILES ClO observations opens up new opportunities to investigate ClO up to the mesopause.

  17. Strato-mesospheric ClO observations by SMILES: error analysis and diurnal variation

    Directory of Open Access Journals (Sweden)

    T. O. Sato

    2012-11-01

    Full Text Available Chlorine monoxide (ClO is the key species for anthropogenic ozone losses in the middle atmosphere. We observed ClO diurnal variations using the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES on the International Space Station, which has a non-sun-synchronous orbit. This includes the first global observations of the ClO diurnal variation from the stratosphere up to the mesosphere. The observation of mesospheric ClO was possible due to 10–20 times better signal-to-noise (S/N ratio of the spectra than those of past or ongoing microwave/submillimeter-wave limb-emission sounders. We performed a quantitative error analysis for the strato- and mesospheric ClO from the Level-2 research (L2r product version 2.1.5 taking into account all possible contributions of errors, i.e. errors due to spectrum noise, smoothing, and uncertainties in radiative transfer model and instrument functions. The SMILES L2r v2.1.5 ClO data are useful over the range from 0.01 and 100 hPa with a total error estimate of 10–30 pptv (about 10% with averaging 100 profiles. The SMILES ClO vertical resolution is 3–5 km and 5–8 km for the stratosphere and mesosphere, respectively. The SMILES observations reproduced the diurnal variation of stratospheric ClO, with peak values at midday, observed previously by the Microwave Limb Sounder on the Upper Atmosphere Research Satellite (UARS/MLS. Mesospheric ClO demonstrated an opposite diurnal behavior, with nighttime values being larger than daytime values. A ClO enhancement of about 100 pptv was observed at 0.02 to 0.01 hPa (about 70–80 km for 50° N–65° N from January–February 2010. The performance of SMILES ClO observations opens up new opportunities to investigate ClO up to the mesopause.

  18. Influence of ocean tides on the diurnal and semidiurnal earth rotation variations from VLBI observations

    Science.gov (United States)

    Gubanov, V. S.; Kurdubov, S. L.

    2015-05-01

    The International astrogeodetic standard IERS Conventions (2010) contains a model of the diurnal and semidiurnal variations in Earth rotation parameters (ERPs), the pole coordinates and the Universal Time, arising from lunisolar tides in the world ocean. This model was constructed in the mid-1990s through a global analysis of Topex/Poseidon altimetry. The goal of this study is to try to estimate the parameters of this model by processing all the available VLBI observations on a global network of stations over the last 35 years performed within the framework of IVS (International VLBI Service) geodetic programs. The complexity of the problemlies in the fact that the sought-for corrections to the parameters of this model lie within 1 mm and, thus, are at the limit of their detectability by all currently available methods of ground-based positional measurements. This requires applying universal software packages with a high accuracy of reduction calculations and a well-developed system of controlling the simultaneous adjustment of observational data to analyze long series of VLBI observations. This study has been performed with the QUASAR software package developed at the Institute of Applied Astronomy of the Russian Academy of Sciences. Although the results obtained, on the whole, confirm a high accuracy of the basic model in the IERS Conventions (2010), statistically significant corrections that allow this model to be refined have been detected for some harmonics of the ERP variations.

  19. Interannual Variation of the Surface Temperature of Tropical Forests from Satellite Observations

    Directory of Open Access Journals (Sweden)

    Huilin Gao

    2016-01-01

    Full Text Available Land surface temperatures (LSTs within tropical forests contribute to climate variations. However, observational data are very limited in such regions. This study used passive microwave remote sensing data from the Special Sensor Microwave/Imager (SSM/I and the Special Sensor Microwave Imager Sounder (SSMIS, providing observations under all weather conditions, to investigate the LST over the Amazon and Congo rainforests. The SSM/I and SSMIS data were collected from 1996 to 2012. The morning and afternoon observations from passive microwave remote sensing facilitate the investigation of the interannual changes of LST anomalies on a diurnal basis. As a result of the variability of cloud cover and the corresponding reduction of solar radiation, the afternoon LST anomalies tend to vary more than the morning LST anomalies. The dominant spatial and temporal patterns for interseasonal variations of the LST anomalies over the tropical rainforest were analyzed. The impacts of droughts and El Niños on this LST were also investigated. Differences between early morning and late afternoon LST anomalies were identified by the remote sensing product, with the morning LST anomalies controlled by humidity (according to comparisons with the National Centers for Environmental Prediction (NCEP reanalysis data.

  20. Temporal variations and sources of Eastern Mediterranean aerosols based on a 9-year observation

    Science.gov (United States)

    Öztürk, F.; Zararsız, A.; Dutkiewicz, V. A.; Husain, L.; Hopke, P. K.; Tuncel, G.

    2012-12-01

    Concentrations of 48 elements, NO3-, SO42-, Cl-, NH4+, and black carbon (BC) were determined in PM10 aerosols collected daily at a rural Eastern Mediterranean (EM) site (Antalya, 30.34°E, 36.47°N) from 1993 to 2001. Temporal variations (daily, seasonal and long term), sources and source regions of EM aerosols were delineated. Concentrations of elements with marine and crustal origin were more episodic as compared to anthropogenic ones. Most of the variables showed well defined seasonal cycles. Concentrations of crustal elements increased in summer while winter concentrations of marine elements were considerably higher than in summer. Trends in concentrations were analyzed using the Kendall test. Essentially, all elements showed decreasing trends. Sen's slope was applied to find the magnitude of the trends. The annual rate of decrease was found to change from 0.001 to 209 ng m-3. A receptor-based model, Positive Matrix Factorization (PMF), resolved five factors influencing the chemical composition of EM aerosols as airborne dust, oil combustion, coal combustion, motor vehicle emissions and sea salt. Potential Source Contribution Function (PSCF) analysis was performed to identify the likely areas influencing the chemical composition of aerosol samples. Local and remote sources were detected for the factors resolved by PMF. PSCF maps including backward trajectories at starting height of 900 hPa have indicated that North Africa is the major source contributing to the concentrations of variables associated with dust factor.

  1. Spectral Variation of the Seyfert 1 Galaxy MCG-6-30-15 observed with Suzaku

    CERN Document Server

    Miyakawa, Takehiro; Terashima, Yuichi; Tsuchihashi, Fuminori; Inoue, Hajime; Zycki, Piotr

    2009-01-01

    We have investigated spectral variation of the Seyfert 1 galaxy MCG-6-30-15 observed with Suzaku in January 2006 for three separate periods spreading over fourteen days. We found that the time-averaged continuum energy spectrum between 1 keV and 40 keV can be approximated with a spectral model composed of the direct power-law component, its reflection component, two warm absorbers with different ionization states, and neutral absorption. We have taken two approaches to study its spectral variation at various timescales: The first approach is to make intensity-sliced spectra and study correlation between the intensity and spectral shape. The second approach is to study spectral changes between the intervals when the source flux is above ("bright state") and below ("faint state") the average for fixed time-intervals. In both approaches, we found a clear correlation between the intensity in the 6 -- 10 keV band and the spectral ratio of 0.5 -- 3.0 keV/6.0-- 10 keV. Such a spectral variation requires change of th...

  2. Observed Gamma Ray Radiation Variations Associated with Tropical Zone Rainfall Events

    Science.gov (United States)

    Spjeldvik, W. N.; Martin, I. M.; Gusev, A. A.

    2014-12-01

    Major liquid precipitation events are associated with changes in measurable natural nuclear radiation at ground level. We have observed that gamma radiation from airborne constituents varies with weather conditions, especially rainfall events, as observed with ground level instrumentation at near tropical zone low latitudes. Simultaneous observations of natural gamma ray emissions at the ground level and tropical zone rainfall variation observations have been performed in Sao Jose dos Campos, Sao Paulo, Brazil with temporal resolution accuracy of the order of one minute. This has allowed a detailed comparison of rainfall amounts and monitored gamma ray emission time profiles to estimate the actual radionuclide concentration in the rainwater. The radionuclide fallout time profiles were numerically simulated from the observed gamma rate through a numerical minimization procedure. The radionuclide concentration was calculated as a ratio of the simulated fallout to that of the observed rainfall amounts. Our result shows an anti-correlation between the average values of these parameters at times. The effect is especially pronounced at rapid rainfall onsets. The results obtained are compared with the current models and data, and the causes are discussed. Future research will study gamma ray radiation versus weather events at ground level in the temporal zone (North America) where the natural background radiation is thought to be generally somewhat lower than at ground level on the South American continent.

  3. Strato-mesospheric ClO observations by SMILES: error analysis and diurnal variation

    Directory of Open Access Journals (Sweden)

    T. O. Sato

    2012-07-01

    Full Text Available Chlorine monoxide (ClO is the key species for anthropogenic ozone loss in the middle atmosphere. We observed the ClO diurnal variation using the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES on the International Space Station which has a non sun-synchronous orbit. This is the first global observation of the ClO diurnal variation from the stratosphere up to the mesosphere. The SMILES observation reproduced the diurnal variation of stratospheric ClO, an enhancement during a daytime, as observed by the Microwave Limb Sounder on the Upper Atmosphere Research Satellite (UARS/MLS. Mesospheric ClO has shown a different diurnal behavior with an enhancement during nighttime. The ClO enhancement was found at a pressure of 0.02 hPa (about 70 km with an amplitude of about 100 pptv and reached up to 0.01 hPa (80 km in the zonal mean of 50° N–65° N in January–February 2010. The observation of mesospheric ClO was possible due to the 10–20 times better signal-to-noise ratio of the spectra than those of past microwave/submillimeter-wave limb-emission sounders. We performed a quantitative error analysis for the strato- and mesospheric ClO of the Level-2 research (L2r product version 2.1.5 taking into account all possible error contributions; i.e. errors due to spectrum noise, smoothing and uncertainties in the radiative transfer model and instrument function. The SMILES L2r v2.1.5 ClO data are useful over the range 0.01 and 100 hPa with a total error of 10–30 pptv (about 10% with averaging of 100 profiles. The vertical resolution is 3–5 km and 5–8 km for the stratosphere and mesosphere, respectively. The performance of the SMILES observation opens the new opportunity to investigate ClO up to the mesopause.

  4. Spectroscopic Observation of Chemical Interaction Between Impact-induced Vapor Clouds and the Ambient Atmosphere

    Science.gov (United States)

    Sugita, S.; Heineck, J. T.; Schultz, P. H.

    2000-01-01

    Chemical reactions within impact-induced vapor clouds were observed in laboratory experiments using a spectroscopic method. The results indicate that projectile-derived carbon-rich vapor reacts intensively with atmospheric nitrogen.

  5. Variations in amounts and potential sources of volatile organic chemicals in new cars

    Energy Technology Data Exchange (ETDEWEB)

    Chien, Y.-C. [Department Industrial Safety and Health, Hungkuang University, 34 Chung-chie Road, Shalu 433, Taiwan (China)]. E-mail: yc@sunrise.hk.edu.tw

    2007-09-01

    This study examines inter-brand, intra-brand and intra-model variations in volatile organic chemical (VOC) levels inside new cars. The effect of temperature on interior VOC levels was examined using model automobiles with and without the air-conditioning running. Potential sources of VOC were assessed by comparing VOC levels with two interior trims (leather and fabric) and by analyzing VOC emissions from various interior components. Five brands of new car, both domestic and imported, were tested. Twelve targeted VOCs were collected on solid sorbents and analyzed using thermal desorption and GC/FID. VOCs from interior parts and adhesives were identified using solid phase micro-extraction (SPME) coupled with GC/MS. The VOC concentrations varied markedly among brands and within models, and individual VOC levels ranged from below the detection limit (a few {mu}g per cubic meter) to thousands of {mu}g per cubic meter. The intra-model variability (mean, 47%) in the VOC levels was approximately 50% that within each brand (mean, 95%). Although interior trim levels affected VOC levels, the effects differed among brands. Reduction of the cabin temperature reduced most VOC levels, but the impact was not statistically significant. Screening tests for VOCs from interior parts revealed that butylated hydroxytoluene (BHT), a common anti-oxidant, was the most common chemical. Long-chain aliphatic hydrocarbons, particularly C14-C17, were identified in most grease (lubricant) samples, and toluene and xylenes were ubiquitously present in adhesive samples. Process-related compounds, such as plasticizer, were also identified in interior parts. In-cabin VOC levels varied significantly among makes/models and interior trims. Concerned consumers should purchase older new cars from manufacturers since VOC levels inside car cabins normally declines over time. Improved processes or materials with lower VOC emission potential should be used to minimize in-cabin VOC sources for new cars.

  6. Variations in amounts and potential sources of volatile organic chemicals in new cars

    International Nuclear Information System (INIS)

    This study examines inter-brand, intra-brand and intra-model variations in volatile organic chemical (VOC) levels inside new cars. The effect of temperature on interior VOC levels was examined using model automobiles with and without the air-conditioning running. Potential sources of VOC were assessed by comparing VOC levels with two interior trims (leather and fabric) and by analyzing VOC emissions from various interior components. Five brands of new car, both domestic and imported, were tested. Twelve targeted VOCs were collected on solid sorbents and analyzed using thermal desorption and GC/FID. VOCs from interior parts and adhesives were identified using solid phase micro-extraction (SPME) coupled with GC/MS. The VOC concentrations varied markedly among brands and within models, and individual VOC levels ranged from below the detection limit (a few μg per cubic meter) to thousands of μg per cubic meter. The intra-model variability (mean, 47%) in the VOC levels was approximately 50% that within each brand (mean, 95%). Although interior trim levels affected VOC levels, the effects differed among brands. Reduction of the cabin temperature reduced most VOC levels, but the impact was not statistically significant. Screening tests for VOCs from interior parts revealed that butylated hydroxytoluene (BHT), a common anti-oxidant, was the most common chemical. Long-chain aliphatic hydrocarbons, particularly C14-C17, were identified in most grease (lubricant) samples, and toluene and xylenes were ubiquitously present in adhesive samples. Process-related compounds, such as plasticizer, were also identified in interior parts. In-cabin VOC levels varied significantly among makes/models and interior trims. Concerned consumers should purchase older new cars from manufacturers since VOC levels inside car cabins normally declines over time. Improved processes or materials with lower VOC emission potential should be used to minimize in-cabin VOC sources for new cars

  7. Quantifying Uncertainty in Daily Temporal Variations of Atmospheric NH3 Emissions Following Application of Chemical Fertilizers

    Science.gov (United States)

    Balasubramanian, S.; Koloutsou-Vakakis, S.; Rood, M. J.

    2014-12-01

    Improving modeling predictions of atmospheric particulate matter and deposition of reactive nitrogen requires representative emission inventories of precursor species, such as ammonia (NH3). Anthropogenic NH3 is primarily emitted to the atmosphere from agricultural sources (80-90%) with dominant contributions (56%) from chemical fertilizer usage (CFU) in regions like Midwest USA. Local crop management practices vary spatially and temporally, which influence regional air quality. To model the impact of CFU, NH3 emission inputs to chemical transport models are obtained from the National Emission Inventory (NEI). NH3 emissions from CFU are typically estimated by combining annual fertilizer sales data with emission factors. The Sparse Matrix Operator Kernel Emissions (SMOKE) model is used to disaggregate annual emissions to hourly scale using temporal factors. These factors are estimated by apportioning emissions within each crop season in proportion to the nitrogen applied and time-averaged to the hourly scale. Such approach does not reflect influence of CFU for different crops and local weather and soil conditions. This study provides an alternate approach for estimating temporal factors for NH3 emissions. The DeNitrification DeComposition (DNDC) model was used to estimate daily variations in NH3 emissions from CFU at 14 Central Illinois locations for 2002-2011. Weather, crop and soil data were provided as inputs. A method was developed to estimate site level CFU by combining planting and harvesting dates, nitrogen management and fertilizer sales data. DNDC results indicated that annual NH3 emissions were within ±15% of SMOKE estimates. Daily modeled emissions across 10 years followed similar distributions but varied in magnitudes within ±20%. Individual emission peaks on days after CFU were 2.5-8 times greater as compared to existing estimates from SMOKE. By identifying the episodic nature of NH3 emissions from CFU, this study is expected to provide improvements

  8. The diurnal variation in stratospheric ozone from the MACC reanalysis, the ERA-Interim reanalysis, WACCM and Earth observation data: characteristics and intercomparison

    Science.gov (United States)

    Schanz, A.; Hocke, K.; Kämpfer, N.; Chabrillat, S.; Inness, A.; Palm, M.; Notholt, J.; Boyd, I.; Parrish, A.; Kasai, Y.

    2014-12-01

    In this study we compare the diurnal variation in stratospheric ozone derived from free-running simulations of the Whole Atmosphere Community Climate Model (WACCM) and from reanalysis data of the atmospheric service MACC (Monitoring Atmospheric Composition and Climate) which both use a similar stratospheric chemistry module. We find good agreement between WACCM and the MACC reanalysis for the diurnal ozone variation in the high-latitude summer stratosphere based on photochemistry. In addition, we consult the ozone data product of the ERA-Interim reanalysis. The ERA-Interim reanalysis ozone system with its long-term ozone parametrization can not capture these diurnal variations in the upper stratosphere that are due to photochemistry. The good dynamics representations, however, reflects well dynamically induced ozone variations in the lower stratosphere. For the high-latitude winter stratosphere we describe a novel feature of diurnal variation in ozone where changes of up to 46.6% (3.3 ppmv) occur in monthly mean data. For this effect good agreement between the ERA-Interim reanalysis and the MACC reanalysis suggest quite similar diurnal advection processes of ozone. The free-running WACCM model seriously underestimates the role of diurnal advection processes at the polar vortex at the two tested resolutions. The intercomparison of the MACC reanalysis and the ERA-Interim reanalysis demonstrates how global reanalyses can benefit from a chemical representation held by a chemical transport model. The MACC reanalysis provides an unprecedented description of the dynamics and photochemistry of the diurnal variation of stratospheric ozone which is of high interest for ozone trend analysis and research on atmospheric tides. We confirm the diurnal variation in ozone at 5 hPa by observations of the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) experiment and selected sites of the Network for Detection of Atmospheric Composition Change (NDACC). The latter

  9. The diurnal variation in stratospheric ozone from the MACC reanalysis, the ERA-Interim reanalysis, WACCM and Earth observation data: characteristics and intercomparison

    Directory of Open Access Journals (Sweden)

    A. Schanz

    2014-12-01

    Full Text Available In this study we compare the diurnal variation in stratospheric ozone derived from free-running simulations of the Whole Atmosphere Community Climate Model (WACCM and from reanalysis data of the atmospheric service MACC (Monitoring Atmospheric Composition and Climate which both use a similar stratospheric chemistry module. We find good agreement between WACCM and the MACC reanalysis for the diurnal ozone variation in the high-latitude summer stratosphere based on photochemistry. In addition, we consult the ozone data product of the ERA-Interim reanalysis. The ERA-Interim reanalysis ozone system with its long-term ozone parametrization can not capture these diurnal variations in the upper stratosphere that are due to photochemistry. The good dynamics representations, however, reflects well dynamically induced ozone variations in the lower stratosphere. For the high-latitude winter stratosphere we describe a novel feature of diurnal variation in ozone where changes of up to 46.6% (3.3 ppmv occur in monthly mean data. For this effect good agreement between the ERA-Interim reanalysis and the MACC reanalysis suggest quite similar diurnal advection processes of ozone. The free-running WACCM model seriously underestimates the role of diurnal advection processes at the polar vortex at the two tested resolutions. The intercomparison of the MACC reanalysis and the ERA-Interim reanalysis demonstrates how global reanalyses can benefit from a chemical representation held by a chemical transport model. The MACC reanalysis provides an unprecedented description of the dynamics and photochemistry of the diurnal variation of stratospheric ozone which is of high interest for ozone trend analysis and research on atmospheric tides. We confirm the diurnal variation in ozone at 5 hPa by observations of the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES experiment and selected sites of the Network for Detection of Atmospheric Composition Change (NDACC

  10. Chemical Variation in Molecular Cloud Cores in the Orion A Cloud

    CERN Document Server

    Tatematsu, Ken'ichi; Kandori, Ryo; Umemoto, Tomofumi

    2010-01-01

    We have observed molecular cloud cores in the Orion A giant molecular cloud (GMC) in CCS, HC3N, DNC, and HN13C to study their chemical characteristics. We have detected CCS in the Orion A GMC for the first time. CCS was detected in about a third of the observed cores. The cores detected in CCS are not localized but are widely distributed over the Orion A GMC. The CCS peak intensity of the core tends to be high in the southern region of the Orion A GMC. The HC3N peak intensity of the core also tends to be high in the southern region, while there are HC3N intense cores near Orion KL, which is not seen in CCS. The core associated with Orion KL shows broad HC3N line profile, and star formation activity near Orion KL seems to enhance the HC3N emission. The column density ratio of NH3 to CCS is lower near the middle of the filament, and is higher toward the northern and southern regions along the Orion A GMC filament. This ratio is known to trace the chemical evolution in nearby dark cloud cores, but seems to be af...

  11. Evaluation of UTLS carbon monoxide simulations in GMI and GEOS-Chem chemical transport models using Aura MLS observations

    Science.gov (United States)

    Huang, Lei; Jiang, Jonathan H.; Murray, Lee T.; Damon, Megan R.; Su, Hui; Livesey, Nathaniel J.

    2016-05-01

    This study evaluates the distribution and variation of carbon monoxide (CO) in the upper troposphere and lower stratosphere (UTLS) during 2004-2012 as simulated by two chemical transport models, using the latest version of Aura Microwave Limb Sounder (MLS) observations. The simulated spatial distributions, temporal variations and vertical transport of CO in the UTLS region are compared with those observed by MLS. We also investigate the impact of surface emissions and deep convection on CO concentrations in the UTLS over different regions, using both model simulations and MLS observations. Global Modeling Initiative (GMI) and GEOS-Chem simulations of UTLS CO both show similar spatial distributions to observations. The global mean CO values simulated by both models agree with MLS observations at 215 and 147 hPa, but are significantly underestimated by more than 40 % at 100 hPa. In addition, the models underestimate the peak CO values by up to 70 % at 100 hPa, 60 % at 147 hPa and 40 % at 215 hPa, with GEOS-Chem generally simulating more CO at 100 hPa and less CO at 215 hPa than GMI. The seasonal distributions of CO simulated by both models are in better agreement with MLS in the Southern Hemisphere (SH) than in the Northern Hemisphere (NH), with disagreements between model and observations over enhanced CO regions such as southern Africa. The simulated vertical transport of CO shows better agreement with MLS in the tropics and the SH subtropics than the NH subtropics. We also examine regional variations in the relationships among surface CO emission, convection and UTLS CO concentrations. The two models exhibit emission-convection-CO relationships similar to those observed by MLS over the tropics and some regions with enhanced UTLS CO.

  12. Evaluation of UTLS Carbon Monoxide Simulations in GMI and GEOS-Chem Chemical Transport Models using Aura MLS Observations

    Science.gov (United States)

    Huang, Lei; Jiang, Jonathan H.; Murray, Lee T.; Damon, Megan R.; Su, Hui; Livesey, Nathaniel J.

    2016-01-01

    This study evaluates the distribution and variation of carbon monoxide (CO) in the upper troposphere and lower stratosphere (UTLS) during 2004-2012 as simulated by two chemical transport models, using the latest version of Aura Microwave Limb Sounder (MLS) observations. The simulated spatial distributions, temporal variations and vertical transport of CO in the UTLS region are compared with those observed by MLS. We also investigate the impact of surface emissions and deep convection on CO concentrations in the UTLS over different regions, using both model simulations and MLS observations. Global Modeling Initiative (GMI) and GEOS-Chem simulations of UTLS CO both show similar spatial distributions to observations. The global mean CO values simulated by both models agree with MLS observations at 215 and 147 hPa, but are significantly underestimated by more than 40% at 100 hPa. In addition, the models underestimate the peak CO values by up to 70% at 100 hPa, 60% at 147 hPa and 40% at 215 hPa, with GEOS-Chem generally simulating more CO at 100 hPa and less CO at 215 hPa than GMI. The seasonal distributions of CO simulated by both models are in better agreement with MLS in the Southern Hemisphere (SH) than in the Northern Hemisphere (NH), with disagreements between model and observations over enhanced CO regions such as southern Africa. The simulated vertical transport of CO shows better agreement with MLS in the tropics and the SH subtropics than the NH subtropics. We also examine regional variations in the relationships among surface CO emission, convection and UTLS CO concentrations. The two models exhibit emission-convection- CO relationships similar to those observed by MLS over the tropics and some regions with enhanced UTLS CO.

  13. Seasonal variations in fate and removal of trace organic chemical contaminants while operating a full-scale membrane bioreactor.

    Science.gov (United States)

    Trinh, Trang; van den Akker, Ben; Coleman, Heather M; Stuetz, Richard M; Drewes, Jörg E; Le-Clech, Pierre; Khan, Stuart J

    2016-04-15

    Trace organic chemical (TrOC) contaminants are of concern for finished water from water recycling schemes because of their potential adverse environmental and public health effects. Understanding the impacts of seasonal variations on fate and removal of TrOCs is important for proper operation, risk assessment and management of treatment systems for water recycling such as membrane bioreactors (MBRs). Accordingly, this study investigated the fate and removal of a wide range of TrOCs through a full-scale MBR plant during summer and winter seasons. TrOCs included 12 steroidal hormones, 3 xeno-estrogens, 2 pesticides and 23 pharmaceuticals and personal care products. Seasonal differences in the mechanisms responsible for removing some of the TrOCs were evident. In particular the contribution of biotransformation and biomass adsorption to the overall removal of estrone, bisphenol A, 17β-estradiol and triclosan were consistently different between the two seasons. Substantially higher percentage removal via biotransformation was observed during the summer sampling period, which compensated for a reduction in removal attributed to biomass adsorption. The opposite was observed during winter, where the contribution of biotransformation to the overall removal of these TrOCs had decreased, which was offset by an improvement in biomass adsorption. The exact mechanisms responsible for this shift are unknown, however are likely to be temperature related as warmer temperatures can lower sorption efficiency, yet enhance biotransformation of these TrOCs. PMID:26815294

  14. Interannual variation patterns of total ozone and lower stratospheric temperature in observations and model simulations

    Directory of Open Access Journals (Sweden)

    W. Steinbrecht

    2006-01-01

    Full Text Available We report results from a multiple linear regression analysis of long-term total ozone observations (1979 to 2000, by TOMS/SBUV, of temperature reanalyses (1958 to 2000, NCEP, and of two chemistry-climate model simulations (1960 to 1999, by ECHAM4.L39(DLR/CHEM (=E39/C, and MAECHAM4-CHEM. The model runs are transient experiments, where observed sea surface temperatures, increasing source gas concentrations (CO2, CFCs, CH4, N2O, NOx, 11-year solar cycle, volcanic aerosols and the quasi-biennial oscillation (QBO are all accounted for. MAECHAM4-CHEM covers the atmosphere from the surface up to 0.01 hPa (≈80 km. For a proper representation of middle atmosphere (MA dynamics, it includes a parametrization for momentum deposition by dissipating gravity wave spectra. E39/C, on the other hand, has its top layer centered at 10 hPa (≈30 km. It is targeted on processes near the tropopause, and has more levels in this region. Despite some problems, both models generally reproduce the observed amplitudes and much of the observed low-latitude patterns of the various modes of interannual variability in total ozone and lower stratospheric temperature. In most aspects MAECHAM4-CHEM performs slightly better than E39/C. MAECHAM4-CHEM overestimates the long-term decline of total ozone, whereas underestimates the decline over Antarctica and at northern mid-latitudes. The true long-term decline in winter and spring above the Arctic may be underestimated by a lack of TOMS/SBUV observations in winter, particularly in the cold 1990s. Main contributions to the observed interannual variations of total ozone and lower stratospheric temperature at 50 hPa come from a linear trend (up to -10 DU/decade at high northern latitudes, up to -40 DU/decade at high southern latitudes, and around -0.7 K/decade over much of the globe, from the intensity of the polar vortices (more than 40 DU, or 8 K peak to peak, the QBO (up to 20 DU, or 2 K peak to peak, and from

  15. Effects of the observed J2 variations on the Earth's precession and nutation

    Science.gov (United States)

    Ferrándiz, José M.; Baenas, Tomás; Belda, Santiago

    2016-04-01

    The Earth's oblateness parameter J2 is closely related to the dynamical ellipticity H, which factorizes the main components of the precession and the different nutation terms. In most theoretical approaches to the Earth's rotation, with IAU2000 nutation theory among them, H is assumed to be constant. The precession model IAU2006 supposes H to have a conventional linear variation, based on the J2 time series derived mainly from satellite laser ranging (SLR) data for decades, which gives rise to an additional quadratic term of the precession in longitude and some corrections of the nutation terms. The time evolution of J2 is, however, too complex to be well approximated by a simple linear model. The effect of more general models including periodic terms and closer to the observed time series, although still unable to reproduce a significant part of the signal, has been seldom investigated. In this work we address the problem of deriving the effect of the observed J2 variations without resorting to such simplified models. The Hamiltonian approach to the Earth rotation is extended to allow the McCullagh's term of the potential to depend on a time-varying oblateness. An analytical solution is derived by means of a suitable perturbation method in the case of the time series provided by the Center for Space Research (CSR) of the University of Texas, which results in non-negligible contributions to the precession-nutation angles. The presentation focuses on the main effects on the longitude of the equator; a noticeable non-linear trend is superimposed to the linear main precession term, along with some periodic and decadal variations.

  16. Gravity Variations Induced by Changing Snowpack Observed at Conrad Observatory (Austria)

    Science.gov (United States)

    Ressl, Hans; Dorninger, Manfred; Meurers, Bruno

    2016-04-01

    Hydrological processes are usually associated with mass transport. This induces gravity variations observed by superconducting gravimeter (SG) masking the pure geodynamical signal. The present study focusses specifically on gravity variations due to snow accumulation and melting. Measurements of the gravity signal are taken from the SG GWR C025 located at the Conrad Observatory (Austria) in an underground laboratory at about 1000m altitude. In snow rich winters a snowpack of one meter in depth or even more can be observed at this location. Snow height is measured at three different locations to get an idea of its variability. At one place additionally the weight of the snow pack is determined which allows to calculate the snow water equivalent. Gravitational signals are rather different for the accumulation and ablation phase, not only due to the different time scales of these processes but also due to the complex way path of melting water entering the ground beneath of the SG. Two methods, rainfall admittance function and Bouguer reduction, are used to account for the effect of the snow pack. Both have their strengths and weaknesses. They work better for short-term mass transports than for long lasting ones because in the latter case interference with signals of other environmental processes gets more prominent. A few case studies including both accumulation and ablation of snow on different time scales will be discussed.

  17. Searching for color variation on fast rotating asteroids with simultaneous V-J observations

    CERN Document Server

    Polishook, David

    2015-01-01

    Boulders, rocks and regolith on fast rotating asteroids (<2.5 hours) are modeled to slide towards the equator due to a strong centrifugal force and a low cohesion force. As a result, regions of fresh subsurface material can be exposed. Therefore, we searched for color variation on small and fast rotating asteroids. We describe a novel technique in which the asteroid is simultaneously observed in the visible and near-IR wavelength range. In this technique, brightness changes due to atmospheric extinction effects can be calibrated across the visible and near-IR images. We use V- and J-band filters since the distinction in color between weathered and unweathered surfaces on ordinary chondrite-like bodies is most prominent at these wavelengths and can reach ~25%. To test our method, we observed 3 asteroids with Cerro Tololo's 1.3 m telescope. We find ~5% variation of the mean V-J color, but do not find any clearly repeating color signature through multiple rotations. This suggests that no landslides occurred w...

  18. Variations in normal color vision. III. Unique hues in Indian and United States observers

    Science.gov (United States)

    Webster, Michael A.; Webster, Shernaaz M.; Bharadwaj, Shrikant; Verma, Richa; Jaikumar, Jaikishan; Madan, Gitanjali; Vaithilingham, E.

    2002-10-01

    Basic color categories are thought to share a common pattern across linguistic groups, yet the focal colors defining those categories can vary substantially within any single group. We asked whether focal colors can also differ systematically across different groups of individuals living in potentially different color environments, by measuring focal and unique hues for observers in India and the United States. Differences between groups were generally small relative to the within-group variations, consistent with a strong common basis for color naming across diverse contexts. However, for most hues the average settings differed significantly across subpopulations. These differences persisted across testing conditions and thus probably reflect longer-term contextual influences on color appearance judgments. They suggest that while color categories may be qualitatively similar, precisely how the hue spectrum is parsed may differ quantitatively across different populations of observers. Both the between-group and the within-group differences are inconsistent with the differences predicted by common peripheral sources of variation in color vision (e.g., in lens or macular pigment) and may reflect an influence of environmental or cultural differences in focal color choices. 2002 Optical Society of America

  19. Period and amplitude variations in post-common-envelope eclipsing binaries observed with SuperWASP

    CERN Document Server

    Lohr, M E; Anderson, D R; Cameron, A Collier; Faedi, F; Haswell, C A; Hellier, C; Hodgkin, S T; Horne, K; Kolb, U C; Maxted, P F L; Pollacco, D; Skillen, I; Smalley, B; West, R G; Wheatley, P J

    2014-01-01

    Period or amplitude variations in eclipsing binaries may reveal the presence of additional massive bodies in the system, such as circumbinary planets. Here, we have studied twelve previously-known eclipsing post-common-envelope binaries for evidence of such light curve variations, on the basis of multi-year observations in the SuperWASP archive. The results for HW Vir provided strong evidence for period changes consistent with those measured by previous studies, and help support a two-planet model for the system. ASAS J102322-3737.0 exhibited plausible evidence for a period increase not previously suggested; while NY Vir, QS Vir and NSVS 14256825 afforded less significant support for period change, providing some confirmation to earlier claims. In other cases, period change was not convincingly observed; for AA Dor and NSVS 07826147, previous findings of constant period were confirmed. This study allows us to present hundreds of new primary eclipse timings for these systems, and further demonstrates the value...

  20. Comparison of Ensemble and Adjoint Approaches to Variational Optimization of Observational Arrays

    Science.gov (United States)

    Nechaev, D.; Panteleev, G.; Yaremchuk, M.

    2015-12-01

    Comprehensive monitoring of the circulation in the Chukchi Sea and Bering Strait is one of the key prerequisites of the successful long-term forecast of the Arctic Ocean state. Since the number of continuously maintained observational platforms is restricted by logistical and political constraints, the configuration of such an observing system should be guided by an objective strategy that optimizes the observing system coverage, design, and the expenses of monitoring. The presented study addresses optimization of system consisting of a limited number of observational platforms with respect to reduction of the uncertainties in monitoring the volume/freshwater/heat transports through a set of key sections in the Chukchi Sea and Bering Strait. Variational algorithms for optimization of observational arrays are verified in the test bed of the set of 4Dvar optimized summer-fall circulations in the Pacific sector of the Arctic Ocean. The results of an optimization approach based on low-dimensional ensemble of model solutions is compared against a more conventional algorithm involving application of the tangent linear and adjoint models. Special attention is paid to the computational efficiency and portability of the optimization procedure.

  1. Bayesian Analysis of Hmi Images and Comparison to Tsi Variations and MWO Image Observables

    Science.gov (United States)

    Parker, D. G.; Ulrich, R. K.; Beck, J.; Tran, T. V.

    2015-12-01

    We have previously applied the Bayesian automatic classification system AutoClass to solar magnetogram and intensity images from the 150 Foot Solar Tower at Mount Wilson to identify classes of solar surface features associated with variations in total solar irradiance (TSI) and, using those identifications, modeled TSI time series with improved accuracy (r > 0.96). (Ulrich, et al, 2010) AutoClass identifies classes by a two-step process in which it: (1) finds, without human supervision, a set of class definitions based on specified attributes of a sample of the image data pixels, such as magnetic field and intensity in the case of MWO images, and (2) applies the class definitions thus found to new data sets to identify automatically in them the classes found in the sample set. HMI high resolution images capture four observables-magnetic field, continuum intensity, line depth and line width-in contrast to MWO's two observables-magnetic field and intensity. In this study, we apply AutoClass to the HMI observables for images from June, 2010 to December, 2014 to identify solar surface feature classes. We use contemporaneous TSI measurements to determine whether and how variations in the HMI classes are related to TSI variations and compare the characteristic statistics of the HMI classes to those found from MWO images. We also attempt to derive scale factors between the HMI and MWO magnetic and intensity observables.The ability to categorize automatically surface features in the HMI images holds out the promise of consistent, relatively quick and manageable analysis of the large quantity of data available in these images. Given that the classes found in MWO images using AutoClass have been found to improve modeling of TSI, application of AutoClass to the more complex HMI images should enhance understanding of the physical processes at work in solar surface features and their implications for the solar-terrestrial environment.Ulrich, R.K., Parker, D, Bertello, L. and

  2. High time resolution observation and statistical analysis of atmospheric light extinction properties and the chemical speciation of fine particulates

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In recent years,the visibility deterioration caused by regional fine particulate pollution becomes one of the crucial air pollution problems in the urban areas of our country.The rapid variation of visibility and fine particulates make it difficult to estimate the relationship between them precisely and accurately unless high time resolution observation data can be accessed.This study aims to fill this gap in the field of atmospheric science by establishing a formula using multiple linear regressions.Excellent fitting goodness (R2=0.913,n=3167) was obtained using 10 min average of high-resolution real-time light scattering coefficients,light absorption coefficients,main chemical speciation concentration in PM1 and some meteorological parameters from 17 Jan to 16 Feb,2009.It shows that the average light extinction coefficient during the observation in the winter of Shenzhen was measured to be 290 ± 183 Mm?1,consisting of 72% of light scattering and 21% of absorption.In terms of the percentage contribution of PM1 chemical species to the total light extinction,the organic matter was estimated to be most with an average of 45%,followed by ammonium sulfate with an average of 24%.The contributions of black carbon and ammonium nitrate were 17% and 12%,respectively.Besides,the diurnal variation of light extinction was investigated as well in this study.

  3. Variation of proton flux profiles with the observer's latitude in simulated gradual SEP events

    CERN Document Server

    Rodríguez-Gasén, R; Sanahuja, B; Jacobs, C; Poedts, S

    2013-01-01

    We study the variation of the shape of the proton intensity-time profiles in simulated gradual Solar Energetic Particle (SEP) events with the relative observer's position in space with respect to the main direction of propagation of an interplanetary (IP) shock. Using a three-dimensional (3D) magnetohydrodynamic (MHD) code to simulate such a shock, we determine the evolution of the downstream-to-upstream ratios of the plasma variables at its front. Under the assumption of an existing relation between the normalized ratio in speed across the shock front and the injection rate of shock-accelerated particles, we model the transport of the particles and we obtain the proton flux profiles to be measured by a grid of 18 virtual observers located at 0.4 and 1.0 AU, with different latitudes and longitudes with respect to the shock nose. The differences among flux profiles are the result of the way each observer establishes a magnetic connection with the shock front, and we find that changes in the observer's latitude...

  4. OH Airglow and Equatorial Variations Observed by ISUAL Instrument on Board the FORMOSAT 2 Satellite

    Directory of Open Access Journals (Sweden)

    Jan-Bai Nee

    2010-01-01

    Full Text Available OH airglow observed by the ISUAL (Imager of Sprites and Upper Atmospheric Lightning instrument on board the FORMOSAT 2 satellite is reported in this paper. The satellite is sun-synchronous and it returns to the same orbit at the same local time daily. By using this property, we can study the upper atmosphere in detail. With a CCD camera, ISUAL has measured the emission layers of OH Meinel band at 630 nm for several two-week periods in 2004 and 2007 in equatorial regions. ISUAL images are snapshots of the atmosphere 250 km (height _ 1200 km (horizontal distance. These images of OH airglow are analyzed to derive its peak height and latitudinal variations. ISUAL observation is unique in its capability of continuous observation of the upper atmosphere as the satellite travels from south to north along a specific orbit. However, 630 nm filter also measured O(1D at 200 km, and there are interferences between O(1D and OH airglows as as observed from a distance in space. We have studied the overlap of two airglows by simulations, and our final analyses show that OH airglow can be correctly derived with its average peak height of 89 _ 2.1 km usually lying within _ latitude about the equator. ISUAL data reveal detailed structures of equatorial OH airglow such as the existences of a few secondary maxima within the equatorial regions, and the oscillations of the peak latitudes. These results are discussed and compared with previous reports.

  5. No Timing Variations Observed in Third Transit of Snow-Line Exoplanet Kepler-421b

    CERN Document Server

    Dalba, Paul A

    2016-01-01

    We observed Kepler-421 during the anticipated third transit of the snow-line exoplanet Kepler-421b in order to constrain the existence and extent of transit timing variations (TTVs). Previously, the Kepler Spacecraft only observed two transits of Kepler-421b leaving the planet's transit ephemeris unconstrained. Our visible light, time-series observations from the 4.3-meter Discovery Channel Telescope were designed to capture pre-transit baseline and the partial transit of Kepler-421b barring significant TTVs. We use the light curves to assess the probabilities of various transit models using both the posterior odds ratio and the Bayesian Information Criterion (BIC) and find that a transit model with no TTVs is favored to 3.6-sigma confidence. These observations suggest that Kepler-421b is either alone in its system or is only experiencing minor dynamic interactions with an unseen companion. With the Kepler-421b ephemeris constrained, we calculate future transit times and discuss the opportunity to characteriz...

  6. Space weather: recovering the variation of the stellar EUV spectral Energy distribution from the companion exoplanet FUV transit observation

    Science.gov (United States)

    Ben-Jaffel, Lotfi; Guo, Jianheng

    2016-07-01

    The stellar extreme ultraviolet (EUV) irradiation determines the atmospheric properties of exoplanets. Recently, by varying the profiles of the EUV spectral energy distribution (SED), we tested the influences of stellar EUV SEDs on the physical and chemical properties of the escaping atmosphere (Guo & Ben-Jaffel, 2015). One of our major results was that the composition and species distributions in the atmosphere could be dramatically modified by the different profiles of the EUV SED. For exoplanets with a high hydrodynamic escape rate, the amount of atomic hydrogen produced by photoionization at different altitudes can vary by one to two orders of magnitude with the variation of stellar EUV SEDs. For exoplanet HD 189733b, it was possible to explain the time variability observed during transit in the Lyman-α line by the Hubble Space Telescope (HST) between 2010 and 2011 by a change in the EUV SED of the host K star. Our proposed technique provides a straightforward and easy-to-follow proxy to connect the EUV SED of the star with the planetary companion Lyman--α transit absorption, the monitoring of which may provide a direct measure of the stellar EUV flux. Here, we extend our study using new HST FUV observations.

  7. Variation in Chemical Defense Among Natural Populations of Common Toad, Bufo bufo, Tadpoles: the Role of Environmental Factors.

    Science.gov (United States)

    Bókony, Veronika; Móricz, Ágnes M; Tóth, Zsófia; Gál, Zoltán; Kurali, Anikó; Mikó, Zsanett; Pásztor, Katalin; Szederkényi, Márk; Tóth, Zoltán; Ujszegi, János; Üveges, Bálint; Krüzselyi, Dániel; Capon, Robert J; Hoi, Herbert; Hettyey, Attila

    2016-04-01

    Defensive toxins are widespread in nature, yet we know little about how various environmental factors shape the evolution of chemical defense, especially in vertebrates. In this study we investigated the natural variation in the amount and composition of bufadienolide toxins, and the relative importance of ecological factors in predicting that variation, in larvae of the common toad, Bufo bufo, an amphibian that produces toxins de novo. We found that tadpoles' toxin content varied markedly among populations, and the number of compounds per tadpole also differed between two geographical regions. The most consistent predictor of toxicity was the strength of competition, indicating that tadpoles produced more compounds and larger amounts of toxins when coexisting with more competitors. Additionally, tadpoles tended to contain larger concentrations of bufadienolides in ponds that were less prone to desiccation, suggesting that the costs of toxin production can only be afforded by tadpoles that do not need to drastically speed up their development. Interestingly, this trade-off was not alleviated by higher food abundance, as periphyton biomass had negligible effect on chemical defense. Even more surprisingly, we found no evidence that higher predation risk enhances chemical defenses, suggesting that low predictability of predation risk and high mortality cost of low toxicity might select for constitutive expression of chemical defense irrespective of the actual level of predation risk. Our findings highlight that the variation in chemical defense may be influenced by environmental heterogeneity in both the need for, and constraints on, toxicity as predicted by optimal defense theory. PMID:27059330

  8. Low-frequency variation of a zonally localized jet stream: Observation and theory

    International Nuclear Information System (INIS)

    The climatological mean circulation in the extratropics of the Northern Hemisphere is characterized by two zonally localized jet streams over the east coasts of the two major continents. The zonal inhomogeneity of the climatological mean circulation is believed to be a primary factor determining the geographical locations of the maximum activity centers of the atmospheric transients, such as storm tracks over the east coasts of the two major continents and frequent blocking episodes occurring over the central regions of the two oceans. The impact of the transients on the zonally localized jet streams is studied mostly in the linear dynamics framework in terms of so-called open-quotes feedbackclose quotes diagnosis. This study investigates nonlinear instability of a zonally localized jet stream. The emphasis is on the nonlinear adjustment of a zonally localized jet stream associated with the development of the transients via local instability. The adjustment of a zonally localized jet stream would naturally consists of two parts: One is the time-invariant part and the other is the transient part (temporal variation of the adjustment). In conjunction with the observation, the time-mean adjustment is part of the climatological mean flow and hence is open-quotes invisible.close quotes The transient part of the adjustment is evidenced by the changes of the jet streams in terms of both location and intensity. In this study, we tend to relate the transient part of the adjustment of the jet stream to the maximum activity centers of low-frequency variability. The underlying mechanisms that are responsible for the temporal variation of the adjustment will be investigated. The time-mean adjustment will be also studied to better understand the temporal variation of the adjustment

  9. Impacts of observation-driven trait variation on carbon fluxes in an earth system projection

    Science.gov (United States)

    Verheijen, Lieneke; van Bodegom, Peter; Aerts, Rien; Brovkin, Victor

    2014-05-01

    Climate projections are still highly uncertain and differences in predicted terrestrial global carbon budgets by earth system models (ESMs) are large, both with respect to the size and direction of change. Part of these uncertainties in the land carbon dynamics are caused by differences in the modeled functional responses of vegetation in reaction to climatic drivers. In reality, changes in vegetation responses to the environment are driven by processes like species plasticity, acclimation, (genotypic) adaptation, species turnover and shifts in species abundances. These processes can cause shifts within community mean trait values, which in turn are will affect carbon fluxes to and from the system. Because most current dynamic global vegetation models (DGVMs, the terrestrial part of ESMs) are not species based, these processes are not or poorly modeled. The recent availability of a large trait database (TRY-database), including both field measurements and experimental data, enables parameterization of the models with observational trait data. Many community mean trait values correlate with local environmental conditions. Such trait-climate relationships can be used to model variation in traits in DGVMs and allow for spatial and temporal variation in functional vegetation responses. The aim of this study was to identify the impacts of observation-driven trait variation on modeled carbon fluxes in climate projections. We determined and incorporated relationships between observational trait and climate data for each plant functional type (PFT) in the DGVM JSBACH. Within each grid cell, traits were varied every year, based on the local climatic conditions in the model. We also included CO2 acclimation of traits based on FACE-experiments, as projections concern elevated CO2 concentrations. Impacts on global carbon budgets were large; in the simulation with variable traits the high latitudes (temperate, boreal and arctic areas) were stronger carbon sinks and the tropical

  10. Variation in global chemical composition of PM2.5: emerging results from SPARTAN

    Science.gov (United States)

    Snider, Graydon; Weagle, Crystal L.; Murdymootoo, Kalaivani K.; Ring, Amanda; Ritchie, Yvonne; Stone, Emily; Walsh, Ainsley; Akoshile, Clement; Anh, Nguyen Xuan; Balasubramanian, Rajasekhar; Brook, Jeff; Qonitan, Fatimah D.; Dong, Jinlu; Griffith, Derek; He, Kebin; Holben, Brent N.; Kahn, Ralph; Lagrosas, Nofel; Lestari, Puji; Ma, Zongwei; Misra, Amit; Norford, Leslie K.; Quel, Eduardo J.; Salam, Abdus; Schichtel, Bret; Segev, Lior; Tripathi, Sachchida; Wang, Chien; Yu, Chao; Zhang, Qiang; Zhang, Yuxuan; Brauer, Michael; Cohen, Aaron; Gibson, Mark D.; Liu, Yang; Vanderlei Martins, J.; Rudich, Yinon; Martin, Randall V.

    2016-08-01

    , India). Comparison of SPARTAN vs. coincident measurements from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network at Mammoth Cave yielded a high degree of consistency for daily PM2.5 (r2 = 0.76, slope = 1.12), daily sulfate (r2 = 0.86, slope = 1.03), and mean fractions of all major PM2.5 components (within 6 %). Major ions generally agree well with previous studies at the same urban locations (e.g. sulfate fractions agree within 4 % for 8 out of 11 collocation comparisons). Enhanced anthropogenic dust fractions in large urban areas (e.g. Singapore, Kanpur, Hanoi, and Dhaka) are apparent from high Zn : Al ratios.The expected water contribution to aerosols is calculated via the hygroscopicity parameter κv for each filter. Mean aggregate values ranged from 0.15 (Ilorin) to 0.28 (Rehovot). The all-site parameter mean is 0.20 ± 0.04. Chemical composition and water retention in each filter measurement allows inference of hourly PM2.5 at 35 % relative humidity by merging with nephelometer measurements. These hourly PM2.5 estimates compare favourably with a beta attenuation monitor (MetOne) at the nearby US embassy in Beijing, with a coefficient of variation r2 = 0.67 (n = 3167), compared to r2 = 0.62 when κv was not considered. SPARTAN continues to provide an open-access database of PM2.5 compositional filter information and hourly mass collected from a global federation of instruments.

  11. Variation in chemical composition and physical characteristics of cereal grains from different genotypes.

    Science.gov (United States)

    Rodehutscord, Markus; Rückert, Christine; Maurer, Hans Peter; Schenkel, Hans; Schipprack, Wolfgang; Bach Knudsen, Knud Erik; Schollenberger, Margit; Laux, Meike; Eklund, Meike; Siegert, Wolfgang; Mosenthin, Rainer

    2016-04-01

    Genotypes of cereal grains, including winter barley (n = 21), maize (n = 27), oats (n = 14), winter rye (n = 22), winter triticale (n = 21) and winter wheat (n = 29), were assayed for their chemical composition and physical characteristics as part of the collaborative research project referred to as GrainUp. Genotypes of one grain species were grown on the same site, except maize. In general, concentrations of proximate nutrients were not largely different from feed tables. The coefficient of variation (CV) for the ether extract concentration of maize was high because the data pool comprised speciality maize bred for its high oil content. A subset of 8 barley, 20 rye, 20 triticale and 20 wheat samples was analysed to differ significantly in several carbohydrate fractions. Gross energy concentration of cereal grains could be predicted from proximate nutrient concentration with good accuracy. The mean lysine concentration of protein was the highest in oats (4.2 g/16 g N) and the lowest in wheat (2.7 g/16 g N). Significant differences were also detected in the concentrations of macro elements as well as iron, manganese, zinc and copper. Concentrations of arsenic, cadmium and lead were below the limit of detection. The concentration of lower inositol phosphates was low, but some inositol pentaphosphates were detected in all grains. In barley, relatively high inositol tetraphosphate concentration also was found. Intrinsic phytase activity was the highest in rye, followed by triticale, wheat, barley and maize, and it was not detectable in oats. Substantial differences were seen in the thousand seed weight, test weight, falling number and extract viscoelasticity characteristics. The study is a comprehensive overview of the composition of different cereal grain genotypes when grown on the same location. The relevance of the variation in composition for digestibility in different animal species will be subject of other communications. PMID:26829392

  12. The variations of neutron component of lunar radiation background from LEND/LRO observations

    Science.gov (United States)

    Litvak, M. L.; Mitrofanov, I. G.; Sanin, A. B.; Bakhtin, B. N.; Bodnarik, J. G.; Boynton, W. V.; Chin, G.; Evans, L. G.; Harshman, K.; Livengood, T. A.; Malakhov, A.; Mokrousov, M. I.; McClanahan, Т. P.; Sagdeev, R.; Starr, R.

    2016-03-01

    Lunar neutron flux data measured by the Lunar Exploration Neutron Detector (LEND) onboard NASA's Lunar Reconnaissance Orbiter (LRO) were analyzed for the period 2009-2014. We have re-evaluated the instrument's collimation capability and re-estimated the neutron counting rate measured in the Field of View (FOV) of the LEND collimated detectors, and found it to be 1.0±0.1 counts per second. We derived the spectral density of the neutron flux for various lunar regions using our comprehensive numerical model of orbital measurements. This model takes into account the location of the LEND instrument onboard LRO to calculate the surface leakage neutron flux and its propagation to the instrument detectors. Based on this we have determined the lunar neutron flux at the surface to be ~2 neutrons/[cm2 sec] in the epithermal energy range, 0.4 eV to 1 keV. We have also found variations of the lunar neutron leakage flux with amplitude as large as a factor of two, by using multi-year observations to explore variations in the Galactic Cosmic Ray (GCR) flux during the 23rd-24th solar cycles.

  13. Total electron content variations observed at a low latitude GPS station in association to geomagnetic storms

    Science.gov (United States)

    Mendes da Costa, A.; Fonseca Junior, E.; Vilas Boas, J.

    Total electron content (TEC) has been continuously monitored since January 1997, using a GPS dual frequency receiver located at Presidente Prudente (22o 07'S, 51o 22' W). In this paper the enhancements observed in the ionspheric TEC are associated with geomagnetic field variations for six geomagnetic storms that occurred from 1997 to 2000. The events were selected according to the integrity and availability of data. The purpose of this study is to provide a better knowledge of the low-latitude behavior of TEC in association to geomagnetic storms. Quiet-time TEC values were obtained by the average of the five magnetically less disturbed days of the month. These values were subtracted from the TEC hourly averages measured during the period of the magnetic storms. Magnetic field intensity measured on the ground was used for the identification of the storm time variations and the Dst indices were also included as a reference for the latitudes considered. The results showed that moderate geomagnetic storms produce small effects in TEC, intense and super intense (Dst < ~150 nT) geomagnetic storms produce well defined and long lasting TEC enhancements. The super intense storms cause the GPS signals to loose their track and the corresponding TEC values cannot be derived.

  14. The variation of the solar diameter and irradiance : eclipse observation of July, 11, 2010

    CERN Document Server

    Serge, Koutchmy; Jean-Yves, Prado; Philippe, Lamy; Patrick, Rocher

    2012-01-01

    The variation of the solar diameter is the subject of hot debates due to the possible effect on Earth climate and also due to different interpretations of long period solar variabilities, including the total solar irradiance. We shortly review the topic and show that rather long term variations, corresponding to a length well over a a solar magnetic cycle, are interesting to consider. The very recently launched mission "Picard" is entirely devoted to the topic but will just permit a short term evaluation. At the time of the last total solar eclipse of 11/07/2010, several experiments were prepared to precisely measure the transit time of the Moon related to the precise value of the solar diameter. Preliminary results coming from the use of a specially designed CNES photometer, put on different atolls of the French Polynesia, are presented. In addition the results of new experiments devoted to fast observations of flash spectra, including their precise chronodating, are illustrated and discussed. A new definiti...

  15. Seasonal Variation of Frequency of High Current Lightning Discharges Observed by JLDN

    Science.gov (United States)

    Saito, Mikihisa; Ishii, Masaru; Fujii, Fumiyuki; Matsui, Michihiro

    Seasonal variations of number of high current lightning discharges exceeding 100kA observed by JLDN (Japanese Lightning Detection Network) were analyzed. The months with averaged altitudes of -10°C level higher than 5.7km are classified as ordinary summer from the viewpoint of lightning activity. Meanwhile, on the coast of the Sea of Japan, more than 90% of negative high current lightning discharges were -GC (Ground to Cloud) strokes in the months when monthly averaged altitudes of -10°C level are lower than 2.7km. These months are classified as the winter lightning season when upward lightning flashes frequently occur. Months other than winter or summer are classified as spring or autumn. In these seasons, the proportions of positive high current lightning discharges are higher than those of negative discharges like winter. Thus, the charge structure in the thunderclouds of spring and autumn may be similar to that in winter, and high current lightning strokes tend to occur. Since this variation of seasons is different in each area of Japan, relation of seasons, areas, and densities of high current lightning discharges were analyzed.

  16. Concentration variations of atmospheric CO2 observed at Syowa Station, Antarctica from 1984 to 2000

    International Nuclear Information System (INIS)

    Systematic and continuous measurements of the atmospheric CO2 concentration have been carried out at Syowa Station, Antarctica since February 1984. The measurement system was renewed in 1995, but the continuity of the data from the two systems was confirmed by operating them simultaneously. The CO2 data taken for 17 years from 1984 to 2000 showed clear evidence for a seasonal cycle, a secular trend and interannual variations. The seasonal cycle was variable from year to year, with especially larger amplitudes in 1992 and 1998 and a large phase delay in 1993. A rapid increase in the CO2 concentration was observed in 1987, 1994 and 1998 in association with ENSO events. The average rate of the secular CO2 increase for the last 17 years was calculated to be 1.49 ppmv/yr. Short-term CO2 variations with amplitudes of around 1.0 ppmv were found in the austral summer season of several years after 1990, probably due to an intrusion of CO2-depleted air mass into the Antarctic region

  17. Seasonal and diurnal variation of lightning activity over southern Africa and correlation with European whistler observations

    Directory of Open Access Journals (Sweden)

    A. B. Collier

    2006-03-01

    Full Text Available Lightning Imaging Sensor (LIS data have been analysed to ascertain the statistical pattern of lightning occurrence over southern Africa. The diurnal and seasonal variations are mapped in detail. The highest flash rates (107.2 km-2 y-1 occur close to the equator but maxima are also found over Madagascar (32.1 km-2 y-1 and South Africa (26.4 km-2 y-1. A feature of the statistics is a relatively steady contribution from over the ocean off the east coast of South Africa that appears to be associated with the Agulhas current.

    Lightning statistics are of intrinsic meteorological interest but they also relate to the occurrence of whistlers in the conjugate region. Whistler observations are made at Tihany, Hungary. Statistics reveal that the period of most frequent whistler occurrence does not correspond to the maximum in lightning activity in the conjugate region but is strongly influenced by ionospheric illumination and other factors. The whistler/flash ratio, R, shows remarkable variations during the year and has a peak that is narrowly confined to February and March.

  18. Seasonal variation of PM10 chemical constituents in different French urban environments

    Science.gov (United States)

    Salameh, Dalia; Golly, Benjamin; Besombes, Jean Luc; Alleman, Laurent; Favez, Olivier; Jaffrezo, Jean Luc

    2016-04-01

    variability in PM10 levels and in the concentrations of various aerosol components observed at the different studied sites were investigated and compared. Moreover, the PM mass closure has been also obtained, and allowed us to link some of the quantified chemical species with their specific sources. Acknowledgments The authors acknowledge the French Ministry of Environment (MEDDE, Ministère de l'Ecologie, du Développement durable, et de l'Energie) and the national reference laboratory for air quality monitoring (LCSQA) for their funding the different programs and of the collection of PM10 samples.

  19. Temporal and vertical variations of aerosol physical and chemical properties over West Africa: AMMA aircraft campaign in summer 2006

    Directory of Open Access Journals (Sweden)

    A. Matsuki

    2010-09-01

    Full Text Available While the Sahelian belt in West Africa stretches in the border between the global hot-spots of mineral dust and biomass burning aerosols, the presence of West African Monsoon is expected to create significant vertical and temporal variations in the regional aerosol properties through transport and mixing of particles from various sources (mineral dust, biomass burning, sulfates, sea salt. In order to improve our understanding of the evolution of the aerosol-cloud system over such region across the onset of the summer monsoon, the French ATR-42 research aircraft was deployed in Niamey, Niger (13°30' N, 02°05' E in summer 2006, during the three special observation periods (SOPs of the African Monsoon Multidisciplinary Analysis (AMMA project. These three SOPs covered both dry and wet periods before and after the onset of the Western African Monsoon.

    State of the art physico-chemical aerosol measurements on the ATR-42 showed a notable seasonal transition in averaged number size distributions where (i the Aitken mode is dominating over the accumulation mode during the dry season preceding the monsoon arrival and (ii the accumulation mode increasingly gained importance after the onset of the West African monsoon and even dominated the Aitken mode after the monsoon had fully developed. The parameters for the mean log-normal distributions observed in respective layers characterized by the different wind regimes (monsoon layer, SAL, free troposphere are presented, together with the major particle compositions found in the accumulation mode particles. Thereby, results of this study should facilitate radiative transfer calculations, validation of satellite remote sensors, and detailed transport modeling by partners within and outside the AMMA community.

    Extended analysis of the chemical composition of single aerosol particles by a transmission electron microscope (TEM coupled to an energy dispersive X-ray spectrometer (EDX revealed

  20. Rainfall Assimilation Using a New Four-Dimensional Variational Method: A Single-Point Observation Experiment

    Institute of Scientific and Technical Information of China (English)

    LIU Juanjuan; WANG Bin

    2011-01-01

    Accurate forecast of rainstorms associated with the mei-yu front has been an important issue for the Chinese economy and society. In July 1998 a heavy rainstorm hit the Yangzi River valley and received widespread attention from the public because it caused catastrophic damage in China. Several numerical studies have shown that many forecast models, including Pennsylvania State University National Center for Atmospheric Research's fifth-generation mesoscale model (MM5), failed to simulate the heavy precipitation over the Yangzi River valley. This study demonstrates that with the optimal initial conditions from the dimension-reduced projection four-dimensional variational data assimilation (DRP-4DVar) system, MM5 can successfully reproduce these observed rainfall amounts and can capture many important mesoscale features, including the southwestward shear line and the low-level jet stream. The study also indicates that the failure of previous forecasts can be mainly attributed to the lack of mesoscale details in the initial conditions of the models.

  1. Geographical variation in glaucoma prescribing trends in England 2008–2012: an observational ecological study

    Science.gov (United States)

    Wormald, Richard; Khaw, Peng Tee

    2016-01-01

    Objectives To explore (1) the national trend in population-adjusted prescription rates for glaucoma and ocular hypertension (OHT) in England and (2) any geographical variation in glaucoma/OHT prescribing trends and its association with established risk factors for primary open-angle glaucoma (POAG) at the population level. Design Observational ecological study. Setting Primary care in England 2008–2012. Participants All patients who received 1 or more of the 37 778 660 glaucoma/OHT prescription items between 2008 and 2012. Primary and secondary outcome measure methods Glaucoma/OHT prescription statistics for England and its constituent primary care trusts (PCTs) between 2008 and 2012 were divided by annual population estimates to give prescription rates per 100 000 population aged ≥40 years. To examine regional differences, prescription rates and the change in prescription rates between 2008 and 2012 for PCTs were separately entered into multivariable linear regression models with the population proportion aged ≥60 years; the proportion of males; the proportion of West African Diaspora (WAD) ethnicity; PCT funding per capita; Index of Multiple Deprivation 2010 score and its domains. Results Between 2008 and 2012, glaucoma/OHT prescriptions increased from 28 029 to 31 309 items per 100 000 population aged ≥40 years. Between PCTs, nearly a quarter of the variation in prescription rates in 2008 and 2012 could be attributed to age, WAD ethnicity and male gender. The change in prescription rates between 2008 and 2012 was only modestly correlated with age (p=0.003, β=0.234), and income deprivation (p=0.035, β=−0.168). Conclusions Increased population-adjusted glaucoma/OHT prescription rates in the study period were likely due to increased detection of POAG and OHT cases at risk of POAG. Between PCTs, regional variation in overall prescription rates was partly attributable to demographic risk factors for POAG, although the change in

  2. Inferring global and regional methane sources and sinks using isotopic observations and atmospheric chemical transport models

    Science.gov (United States)

    Rigby, M. L.; Wenger, A.; O'Doherty, S.; Lunt, M. F.; Ganesan, A.; Manning, A.; Prinn, R. G.

    2015-12-01

    Measurements of the major isotopologues of atmospheric methane have the potential to improve our understanding of the methane budget at the global and regional scale. Using global and regional chemical transport models, we can predict the atmospheric variations in 13C-CH4 and D-CH4, for given assumptions about source isotope ratios and fractionation due to methane sinks. This information can then be used to test the impact that various measurement techniques, technologies and sampling strategies have on our knowledge of the methane budget. We show that, at the global scale, an extensive and accurate network of isotopic measurements can lead to a reduction in the uncertainties in the major global sources. Furthermore, measurements of the D/H ratio in methane may provide some level of uncertainty reduction in the magnitude of the OH sink. Uncertainties can be reduced with improved precision and accuracy of the atmospheric observations. However, to make the most of an atmospheric methane isotope network, we show that the characterisation of source isotope ratios must also be improved. Finally, we put the theory into practice by deriving sector-specific methane sources at the national scale using 13C-CH4 samples collected as part of the Greenhouse gAs Uk and Global Emissions (GAUGE) project. GAUGE measurements are made from a tall tower site to the east of the UK, a background station on the west coast of Ireland and during intensive aircraft sampling campaigns. We will discuss the challenges and benefits associated with adding isotopic information to a national greenhouse gas sampling network and outline a strategy for improvements in the future.

  3. Latitudinal variation of thermospheric hydrogen near solstice from AE-D observations

    International Nuclear Information System (INIS)

    The authors describe an investigation of the variation of neutral atomic hydrogen with latitude in the thermosphere during a solstice season near solar minimum. Neutral hydrogen concentrations were derived with the charge exchange method applied to in-situ ion and neutral composition measurements in the F region. The primary basic data were acquired with the polar-orbiting AE-D satellite which provided excellent latitudinal coverage within small increments of local time around the December 1975 solstice. Hydrogen concentrations at low latitude are comparable to those found under similar conditions from observations with AE-E satellite but are slightly larger than concentrations given by the MSIS-83 atmospheric model. Results, normalized to 300 km, for a morning-daytime period confirm the general summer-to-winter density increase, the large latitudinal gradients in the summer hemisphere, and the winter enhancement of hydrogen observed in various AE-C nighttime measurements. The AE-D data, however, provide evidence for a small polar depression in hydrogen concentration at high winter latitudes similar to but of lesser latitudinal extent than the inferred from OGO 8 optical observations in the exosphere

  4. [Investigation of variation of the production of biological and chemical compounds of Hyssopus officinalis L].

    Science.gov (United States)

    Varga, E; Hajdú, Z; Veres, K; Máthé, I; Németh, E; Pluhár, Z; Bernáth, J

    1998-05-01

    Hyssopus officinalis L. (Lamiaceae family) has been cultivated in Central Europe for a long time. This essential oil containing species serves not only as spice but in many countries including Hungary, it is used as a folk medicine against certain respiratory diseases. Despite this fact, little is known about the variation of its productivity under Central European climatic conditions. The cultivated populations of hyssop can be characterised by a significant heterogenity. In the course of its breeding the uniformity of flower colour (e.g. blue form), and increase in the oil content are the main achievable purposes. The purpose of this work was to investigate both the variability of strains of different crigin and the time-dependent variations of its production parameters. The optimum of phytomass was obtained at the beginning of July. The essential oil content as well as compounds of the non volatile fractions were also investigated. The non volatile fractions for rosmarinic, caffeic acids were analysed mainly by TLC and densitometry. Both compounds were present in all samples and they are suitable for the characterisation of the plant. The essential oils were gained with Water Steam Distillation (WSD) and Supercritical Fluid Extraction (SFE) with CO2. The oils were analysed by GC, GC-MS techniques. In the essential oil composition of the populations studied significant heterogenity could be observed. In the case of applying SFE extraction the oil composition is more uniform, similarly to the obtained by WSD adding hexane. The heterogenity can be experienced in the offsprings, too. If only the main four components (beta-pinene, limonene, pinocamphone, isopinocamphone) are regarded, among the offsprings clear and mixed lines alike can be found. Results of these experiments justify the necessity and usefulness of selection which is going on. PMID:9703705

  5. A new estimation of the recent tropospheric molecular hydrogen budget using atmospheric observations and variational inversion

    Directory of Open Access Journals (Sweden)

    C. E. Yver

    2011-04-01

    Full Text Available This paper presents an analysis of the recent tropospheric molecular hydrogen (H2 budget with a particular focus on soil uptake and European surface emissions. A variational inversion scheme is combined with observations from the RAMCES and EUROHYDROS atmospheric networks, which include continuous measurements performed between mid-2006 and mid-2009. Net H2 surface flux, then deposition velocity and surface emissions and finally, deposition velocity, biomass burning, anthropogenic and N2 fixation-related emissions were simultaneously inverted in several scenarios. These scenarios have focused on the sensibility of the soil uptake value to different spatio-temporal distributions. The range of variations of these diverse inversion sets generate an estimate of the uncertainty for each term of the H2 budget. The net H2 flux per region (High Northern Hemisphere, Tropics and High Southern Hemisphere varies between −8 and +8 Tg yr−1. The best inversion in terms of fit to the observations combines updated prior surface emissions and a soil deposition velocity map that is based on bottom-up and top-down estimations. Our estimate of global H2 soil uptake is −59±9 Tg yr−1. Forty per cent of this uptake is located in the High Northern Hemisphere and 55% is located in the Tropics. In terms of surface emissions, seasonality is mainly driven by biomass burning emissions. The inferred European anthropogenic emissions are consistent with independent H2 emissions estimated using a H2/CO mass ratio of 0.034 and CO emissions within the range of their respective uncertainties. Additional constraints, such as isotopic measurements would be needed to infer a more robust partition of H2 sources and sinks.

  6. Observer variation in chest radiography of acute lower respiratory infections in children: a systematic review

    International Nuclear Information System (INIS)

    Knowledge of the accuracy of chest radiograph findings in acute lower respiratory infection in children is important when making clinical decisions. I conducted a systematic review of agreement between and within observers in the detection of radiographic features of acute lower respiratory infections in children, and described the quality of the design and reporting of studies, whether included or excluded from the review. Included studies were those of observer variation in the interpretation of radiographic features of lower respiratory infection in children (neonatal nurseries excluded) in which radiographs were read independently and a clinical population was studied. I searched MEDLINE, HealthSTAR and HSRPROJ databases (1966 to 1999), handsearched the reference lists of identified papers and contacted authors of identified studies. I performed the data extraction alone. Ten studies of observer interpretation of radiographic features of lower respiratory infection in children were identified. Seven of the studies satisfied four or more of the seven design and reporting criteria. Six studies met the inclusion criteria for the review. Inter-observer agreement varied with the radiographic feature examined. Kappa statistics ranged from around 0.80 for individual radiographic features to 0.27–0.38 for bacterial vs viral etiology. Little information was identified on observer agreement on radiographic features of lower respiratory tract infections in children. Agreement varied with the features assessed from 'fair' to 'very good'. Aspects of the quality of the methods and reporting need attention in future studies, particularly the description of criteria for radiographic features

  7. New observations of chemically peculiar stars with ESPaDOnS

    CERN Document Server

    Khalack, V; Thibeault, C; LeBlanc, F

    2015-01-01

    We present the first results of the estimation of gravity and effective temperature for some poorly studied chemically peculiar stars that were recently observed with the spectropolarimeter ESPaDOnS at CFHT. We have analyzed the spectra of HD71030, HD95608 and HD116235 to determine their radial velocity, Vsin(i) and the average abundance of several chemical species. We have also analyzed our results to verify for possible vertical abundance stratification of iron and chromium in these stars.

  8. Constraining the Variation of the Fine Structure Constant with Observations of Narrow Quasar Absorption Lines

    CERN Document Server

    Songaila, A

    2014-01-01

    The unequivocal demonstration of temporal or spatial variability in a fundamental constant of nature would be of enormous significance. Recent attempts to measure the variability of the fine structure constant, alpha, over cosmological time, using high resolution spectra of high redshift quasars observed with 10m class telescopes, have produced conflicting results. We used the Many Multiplet (MM) method with Mg II and Fe II lines on very high signal-to-noise, high resolution (R = 72,000) Keck HIRES spectra of eight narrow quasar absorption systems and show, using careful wavelength calibrations, that the systematic wavelength errors are too large for previous observations to have had the sensitivity to detect such variation using this technique. We find no significant change in alpha, Delta(alpha)/alpha =(0.00 +/- 0.24) x 10^(-5), in the redshift range z=0.7-1.5. We also show that the scatter in measurements of Delta(alpha)/alpha arising from line selection can be considerably larger than assigned statistical...

  9. Variation of electron temperature and density observed by DEMETER with other satellites and their empirical model

    Science.gov (United States)

    Kakinami, Yoshihiro; Lebreton, Jean-Pierre; Watanabe, Shigeto; Kamogawa, Masashi; Mogi, Toru

    2012-07-01

    Electron density (Ne) and temperature (Te) observed by the DEMETER satellite are validated comparing with various satellites and empirical models of ionosphere/thermosphere such as Hinotori, Dynamic Explorer 2 (DE2), AE-series, and FORMOSAT3/COMSMIC, models based on satellite mass spectrometer and ground-based incoherent scatter data (the MSIS models) and International Reference Ionosphere (IRI). The results show that the Ne and Te of DEMETER are lower and higher that those observed with the other satellites. Such differences are probably originated from the contamination of the Langmuir probe mounted on DEMETER. Since global-scale ionospheric structures such as wave 4 pattern were clearly seen, the relative values of the Ne and Te is expected to be useful to evaluation. However, tiny variations should be carefully discussed for the research. Using Ne and Te measured by the DEMETER satellite, we construct empirical models of Ne and Te for day (1030 local time) and night time (2230 local time) under the geomagnetic quiet condition (Kp trigonometric and linear function fitting. The empirical model derives Ne and Te as functions of day of year, longitude, latitude and solar activity. The results of the empirical models are compared with IRI and discussed.

  10. Monitoring interannual variation in global crop yield using long-term AVHRR and MODIS observations

    Science.gov (United States)

    Zhang, Xiaoyang; Zhang, Qingyuan

    2016-04-01

    Advanced Very High Resolution Radiometer (AVHRR) and Moderate Resolution Imaging Spectroradiometer (MODIS) data have been extensively applied for crop yield prediction because of their daily temporal resolution and a global coverage. This study investigated global crop yield using daily two band Enhanced Vegetation Index (EVI2) derived from AVHRR (1981-1999) and MODIS (2000-2013) observations at a spatial resolution of 0.05° (∼5 km). Specifically, EVI2 temporal trajectory of crop growth was simulated using a hybrid piecewise logistic model (HPLM) for individual pixels, which was used to detect crop phenological metrics. The derived crop phenology was then applied to calculate crop greenness defined as EVI2 amplitude and EVI2 integration during annual crop growing seasons, which was further aggregated for croplands in each country, respectively. The interannual variations in EVI2 amplitude and EVI2 integration were combined to correlate to the variation in cereal yield from 1982-2012 for individual countries using a stepwise regression model, respectively. The results show that the confidence level of the established regression models was higher than 90% (P value < 0.1) in most countries in the northern hemisphere although it was relatively poor in the southern hemisphere (mainly in Africa). The error in the yield predication was relatively smaller in America, Europe and East Asia than that in Africa. In the 10 countries with largest cereal production across the world, the prediction error was less than 9% during past three decades. This suggests that crop phenology-controlled greenness from coarse resolution satellite data has the capability of predicting national crop yield across the world, which could provide timely and reliable crop information for global agricultural trade and policymakers.

  11. Monitoring soil wetness variations by means of satellite passive microwave observations: the HYDROPTIMET study cases

    Directory of Open Access Journals (Sweden)

    T. Lacava

    2005-01-01

    . This analysis allows us to evaluate the reliability and the efficiency of the proposed technique in identifying different amounts of soil wetness variations in different observational conditions. In particular, the proposed indicator was able to document the actual effects of meteorological events, in terms of space-time evolution of soil wetness changes, for all the analysed HYDROPTIMET test cases. Moreover, in some circumstances, the SWVI was able to identify the presence of a sort of 'early' signal in terms of soil wetness variations, which may be regarded as a timely indication of an anomalous value of soil water content. This evidence suggests the opportunity to use such an index in the pre-operational phases of the modern flood warning systems, in order to improve their forecast capabilities and their reliability.

  12. Comparing Stable Water Isotope Variation in Atmospheric Moisture Observed over Coastal Water and Forests

    Science.gov (United States)

    Lai, C. T.; Rambo, J. P.; Welp, L. R.; Bible, K.; Hollinger, D. Y.

    2014-12-01

    Stable oxygen (δ18O) and hydrogen (δD) isotopologues of atmospheric moisture are strongly influenced by large-scale synoptic weather cycles, surface evapotranspiration and boundary layer mixing. Atmospheric water isotope variation has been shown to empirically relate to relative humidity (Rh) of near surface moisture, and to a less degree, air temperature. Continuous δ18O and δD measurements are becoming more available, providing new opportunities to investigate processes that control isotope variability. This study shows the comparison of δ18O and δD measured at a continental location and over coastal waters for 3 seasons (spring to fall, 2014). The surface moisture isotope measurements were made using two LGR spectroscopy water vapor isotope analyzers (Los Gatos Research Inc.), one operated in an old-growth coniferous forest at Wind River field station, WA (45.8205°N, 121.9519°W), and another sampling marine air over seawater at the Scripps Pier in San Diego, CA (32.8654°N, 117.2536°W), USA. Isotope variations were measured at 1Hz and data were reported as hourly averages with an overall accuracy of ±0.1‰ for δ18O, ±0.5‰ for δ2H. Day-to-day variations in δ18O and δD are shown strongly influenced by synoptic weather events at both locations. Boundary layer mixing between surface moisture and the dry air entrained from the free troposphere exerts a midday maximum and a consistent diel pattern in deuterium excess (dx). At the forest site, surface moisture also interacts with leaf water through transpiration during the day and re-equilibration at night. The latter occurs by retro-diffusion of atmospheric H2O molecules into leaf intercellular space, which becomes intensified as Rh increaes after nightfall, and continues until sunrise, to counter-balance the evaporative isotopic enrichment in leaf water on a daily basis. These vegetation effects lead to negative dx values consistently observed at nighttime in this continental location that were not

  13. Spatiotemporal variations of water vapor content over Ethiopia: A study using GPS observations and ECMWF model

    Science.gov (United States)

    Abraha, Kibrom; Masson, Frédéric; Doubre, Cécile; Boy, Jean-Paul; Lewi, Elias

    2014-05-01

    In this study we characterize the spatial and temporal variability of integrated water vapour (IWV) in Ethiopa from a network of GPS stations. Water vapour plays a major role in atmospheric processes but remains difficult to quantify due to its high variability in time and space and the sparse set of available measurements. Global Positioning Systems (GPS) has demonstrated its ability to monitor IWV with an accuracy comparable to other means of measurements (radiosondes, microwave radiometers, …) and a good time resolution and under all meteorological conditions. IWV values for a set of Ethiopian GPS stations have been estimated from 2007 to 2011. They have also been extracted from European Centre for Medium-Range Weather Forecasts (ECMWF) model, using nearest point from the original reduced Gaussian grid. First we compare the IVW estimated from GPS and from the model. The bias varies from site to site but in general a bias of less than 1 kg/m2 was analysed in the ECMWF data set with respect to GPS observations. The correlations between the two data sets exceed 0.85 at different time scales at a 99.9% significant level. Second we observe the spatial variation of the IWV. High values are obtained in those stations that are located in north-eastern (Afar depression sites) and south-western part of the country. This distribution is related to the spatial variability of the climate in Ethiopia. Finally, we study the diurnal, seasonal cycle and inter-annual variability of IWV for all stations over Ethiopia. The main result is the strong inter-annual variability observed for the dry seasons.

  14. Annual variations in sea surface wind speed around Japan observed by ASCAT

    Science.gov (United States)

    Takeyama, Y.; Shimada, S.; Ohsawa, T.; Kozai, K.; Kogaki, T.

    2015-12-01

    Sea surface wind speeds and these statistics can be applied for many marine industrial activities. For example, the averaged wind speed is crucial information for a site selection of an offshore wind farm. It has widely been recognized that a total amount of the offshore wind generation is strongly depended on the annual average wind speeds. A advanced scatterometer (ASCAT), which is a kind of scatterometer aboard METOP-A and B, has observed sea surface wind speeds at the height of 10 m above the sea surface approximately twice a day using active microwaves. The annual average wind speed can be calculated from the observed wind speed. For an actual use of the annual average wind speed, generalities and representativeness of the wind speed must be clarified. To investigate annual variations in sea surface wind speed around Japan (120°E to 165°E, 19°N to 49°N), the annual average wind speeds and these standard deviations are calculated from 5 years of ASCAT observations from 2010 through 2014. It is found that there are some sea areas where standard deviations are relatively higher than their surroundings. Annual average wind speed maps indicate that the high standard deviation is caused by strong winds from Eurasia in the winter of 2011 in part of North Pacific Ocean and Sea of Okhotsk. Additionally standard deviations for only winter are also higher than for summer in those sea areas. Therefore the strong wind speed in the winter of a particular year can easily affect to the annual average wind speed. Meanwhile off the coast of Niigata and Hokkaido, there are also higher standard deviation areas than their surroundings. Differences between monthly maximum wind speeds for the winter and minimum wind speeds for the summer in these areas are larger and the large differences seem to be a cause of the high standard deviations.

  15. From Observation to Information: Data-Driven Understanding of on Farm Yield Variation.

    Science.gov (United States)

    Jiménez, Daniel; Dorado, Hugo; Cock, James; Prager, Steven D; Delerce, Sylvain; Grillon, Alexandre; Andrade Bejarano, Mercedes; Benavides, Hector; Jarvis, Andy

    2016-01-01

    Agriculture research uses "recommendation domains" to develop and transfer crop management practices adapted to specific contexts. The scale of recommendation domains is large when compared to individual production sites and often encompasses less environmental variation than farmers manage. Farmers constantly observe crop response to management practices at a field scale. These observations are of little use for other farms if the site and the weather are not described. The value of information obtained from farmers' experiences and controlled experiments is enhanced when the circumstances under which it was generated are characterized within the conceptual framework of a recommendation domain, this latter defined by Non-Controllable Factors (NCFs). Controllable Factors (CFs) refer to those which farmers manage. Using a combination of expert guidance and a multi-stage analytic process, we evaluated the interplay of CFs and NCFs on plantain productivity in farmers' fields. Data were obtained from multiple sources, including farmers. Experts identified candidate variables likely to influence yields. The influence of the candidate variables on yields was tested through conditional forests analysis. Factor analysis then clustered harvests produced under similar NCFs, into Homologous Events (HEs). The relationship between NCFs, CFs and productivity in intercropped plantain were analyzed with mixed models. Inclusion of HEs increased the explanatory power of models. Low median yields in monocropping coupled with the occasional high yields within most HEs indicated that most of these farmers were not using practices that exploited the yield potential of those HEs. Varieties grown by farmers were associated with particular HEs. This indicates that farmers do adapt their management to the particular conditions of their HEs. Our observations confirm that the definition of HEs as recommendation domains at a small-scale is valid, and that the effectiveness of distinct

  16. From Observation to Information: Data-Driven Understanding of on Farm Yield Variation.

    Directory of Open Access Journals (Sweden)

    Daniel Jiménez

    Full Text Available Agriculture research uses "recommendation domains" to develop and transfer crop management practices adapted to specific contexts. The scale of recommendation domains is large when compared to individual production sites and often encompasses less environmental variation than farmers manage. Farmers constantly observe crop response to management practices at a field scale. These observations are of little use for other farms if the site and the weather are not described. The value of information obtained from farmers' experiences and controlled experiments is enhanced when the circumstances under which it was generated are characterized within the conceptual framework of a recommendation domain, this latter defined by Non-Controllable Factors (NCFs. Controllable Factors (CFs refer to those which farmers manage. Using a combination of expert guidance and a multi-stage analytic process, we evaluated the interplay of CFs and NCFs on plantain productivity in farmers' fields. Data were obtained from multiple sources, including farmers. Experts identified candidate variables likely to influence yields. The influence of the candidate variables on yields was tested through conditional forests analysis. Factor analysis then clustered harvests produced under similar NCFs, into Homologous Events (HEs. The relationship between NCFs, CFs and productivity in intercropped plantain were analyzed with mixed models. Inclusion of HEs increased the explanatory power of models. Low median yields in monocropping coupled with the occasional high yields within most HEs indicated that most of these farmers were not using practices that exploited the yield potential of those HEs. Varieties grown by farmers were associated with particular HEs. This indicates that farmers do adapt their management to the particular conditions of their HEs. Our observations confirm that the definition of HEs as recommendation domains at a small-scale is valid, and that the effectiveness of

  17. Surface water storage variations in Anatolia and Surrounding Territories observed by GRACE

    Science.gov (United States)

    Akyilmaz, O.; Mercan, H.

    2012-04-01

    NASA/GFZ's joint satellite-to-satellite tracking mission GRACE has the primary science objective of measuring climate-sensitive signals generated by mass redistributions on Earth including the oceans and land at spatial scales greater than several hundred km and temporal scales longer than 30 days. Its main science data include the monthly time series of global geopotential models in terms of spherical harmonic coefficients (SHC) which is one of the so-called L2 data products. As the well-known effects on the orbital perturbations such as the planetary bodies, ocean tides, solid Earth tides and other high-frequency variations in ocean and atmosphere are forward modeled prior to the estimation of monthly SHC, the difference between the SHC mainly represents the changes of climate sensitive signals such as hydrology, ice sheet mass balance and ocean mass change. Although the SHC still include the residual effects of tides and atmosphere due to imperfect models and temporal aliasing, recent studies have shown that the hydrology signal can be estimated with an accuracy of several cm in equivalent water tickness and a resolution of several hundred km. One other way to estimate the hydrology signal is the regional inversion method where we use the in situ intersatellite potential difference observations computed based on the energy conservation principle (Jekeli, 1999). To this end, we use the GRACE L1B data products such as range rate, accelerometer and star camera data for the energy integral of the satellites. The well known effects, N-body tides, ocean and solid Earth tides, the high frequency atmospheric mass variations and barotropic ocean response due to atmospheric forcing are forward modeled based on best current models and ancillary data and removed from the in-situ potential differences. The remaining in-situ potential differences are then used as observations based on Newton's law of gravitation to estimate the surface water mass changes with respect to a

  18. Variation of atmospheric CO, δ13C, and δ18O at high northern latitude during 2004-2009: Observations and model simulations

    Science.gov (United States)

    Park, Keyhong; Wang, Zhihui; Emmons, Louisa K.; Mak, John E.

    2015-10-01

    Atmospheric CO mixing ratios and stable isotope ratios (δ13C and δ18O) were measured at a high northern latitude site (Westman Islands, Iceland) from January 2004 to March 2010 in order to investigate recent multiyear trends of the sources of atmospheric carbon monoxide in the extratropical Northern Hemisphere. During this period, we observed a decrease of about 2% per year in CO mixing ratios with little significant interannual variability. The seasonal cycles for δ13C and δ18O in CO are similar to that in the CO mixing ratio, and there is a pronounced interannual variation in their seasonal extremes occurring in summer and fall, which is driven by changes in the relative contribution of different sources. Some of the sources of CO are anthropogenic in character (e.g., fossil fuel and biofuel combustion and agricultural waste burning), and some are primarily natural (e.g., oxidation atmospheric methane and other hydrocarbons and wildfires), and distinction among the various major sources can, more or less, be distinguished by the stable isotopic composition of CO. We compare our observations with simulations from a 3-D global chemical transport model (MOZART-4, Model for Ozone and Related Chemical Tracers, version 4). Our results indicate the observed trend of anthropogenic CO emissions is mostly responsible for the observed variation in δ13C and δ18O of CO during 2004-2009. Especially, the δ18O enriched sources such as fossil fuel and biofuel sources are controlling the variation. The modeling results indicate decreasing trends in the fossil fuel and biofuel source contributions at Iceland of -0.61 ± 0.26 ppbv/yr and -0.38 ± 0.10 ppbv/yr, respectively, during the observation period.

  19. Chemical variations observed in irradiated, treated with IPC and control potato tubers

    International Nuclear Information System (INIS)

    The content in soluble sugars, ascorbic acid and phenolic acids of potato tubers preserved by irradiation and IPC, during storage period of five months are studied. In the irradiated tubers, soluble sugars increased immediately after the irradiation, in relation to the control tubers reaching inferior values to those reached by the control tubers, at the end of the storage period. The content in ascorbic acid is generally kept higher in the irradiated and IPC treated tubers than in the control tubers and the content in phenolic acids increased in the irradiated and IPC treated tubers by immediate effect of this treatment. (Author) 39 refs

  20. Variations in chemical fingerprints and major flavonoid contents from the leaves of thirty-one accessions of Hibiscus sabdariffa L.

    Science.gov (United States)

    Wang, Jin; Cao, Xianshuang; Ferchaud, Vanessa; Qi, Yadong; Jiang, Hao; Tang, Feng; Yue, Yongde; Chin, Kit L

    2016-06-01

    The leaves of Hibiscus sabdariffa L. have been used as traditional folk medicines for treating high blood pressure and fever. There are many accessions of H. sabdariffa L. throughout the world. To assess the chemical variations of 31 different accessions of H. sabdariffa L., fingerprinting analysis and quantitation of major flavonoids were performed by high-performance liquid chromatography (HPLC). The HPLC method was validated for linearity, sensitivity, precision, repeatability and accuracy. A quadrupole-time-of-flight mass spectrometry (Q-TOF-MS) was applied for the characterization of major compounds. A total of 9 compounds were identified, including 6 flavonoids and 3 phenolic acids. In the fingerprint analysis, similarity analysis (SA) and principal component analysis (PCA) were used to differentiate the 31 accessions of H. sabdariffa L. Based on the results of PCA and SA, the samples No. 15 and 19 appeared much different from the main group. The total content of five flavonoids varied greatly among different accessions, ranging from 3.35 to 23.30 mg/g. Rutin was found to be the dominant compound and the content of rutin could contribute to chemical variations among different accessions. This study was helpful to understand the chemical variations between different accessions of H. sabdariffa L., which could be used for quality control. © 2015 The Authors Biomedical Chromatography Published by John Wiley & Sons Ltd. PMID:26394363

  1. Temporal variation of the cloud top height over the tropical Pacific observed by geostationary satellites

    Science.gov (United States)

    Nishi, N.; Hamada, A.

    2012-12-01

    lower cloud top height (6-10 km) is kept within one-two days. A typical example is observed on 5 January 2011 in a dissipating cloud system with 1000-km scale. This cluster located between 0-10N just west of the International Date Line and moved westward with keeping relatively lower cloud top (6-10 km) over one day. This top height is lower than the ubiquitous upper-tropospheric stratiform clouds but higher than the so-called 'congestus cloud' whose top height is around 0C. CloudSat data show the presence of convective rainfall. It suggests that this cloud system continuously kept making new anvil clouds in a little lower height than usual. We examined the seasonal variation of the distribution of cloud systems with a little lower cloud top height (6-11 km) during 2010-11. The number of such cloud systems is not constant with seasons but frequently increased in some specific seasons. Over the equatorial ocean region (east of 150E), they were frequently observed during the northern winter.

  2. Lidar observations of wind over Xin Jiang, China: general characteristics and variation

    Science.gov (United States)

    Han, Yan; Sun, Dong-song; Weng, Ning-quan; Wang, Jian-guo; Dou, Xian-kang; Zhang, Yan-hong; Guan, Jun; Miao, Qingjian; Chen, Xin

    2016-08-01

    The mobile Rayleigh Doppler lidar based on a Fabry-Perot etalon is developed for wind measurement. The structure and technical parameters of this lidar system are described in brief. The 1740 wind profiles from 8 to 40 km altitudes by the lidar in Xinjiang, China, were obtained in 2010 and 2011, and were used to analyze the characteristics and variations of wind. The results shown that the wind velocity is within a three-layer structure: westerly jet layer (9-14 km), quasi-zero velocity layer (18-22 km) and gale layer (22-40 km). In August and September, the wind direction is within a three-layer structure: zonal westerly wind layer (5-18 km) where wind direction is west, zonal wind reverse layer (18-22 km) where wind direction is unstable and easterly wind layer (22-40 km) where wind direction is east. In October, wind direction is west (8-40 km). Wind observations by lidar are a realistic offset to the rawins.

  3. A new estimation of the recent tropospheric molecular hydrogen budget using atmospheric observations and variational inversion

    Directory of Open Access Journals (Sweden)

    C. Yver

    2010-11-01

    Full Text Available This paper presents an analysis of the recent tropospheric molecular hydrogen (H2 budget with a particular focus on soil uptake and surface emissions. A variational inversion scheme is combined with observations from the RAMCES and EUROHYDROS atmospheric networks, which include continuous measurements performed between mid-2006 and mid-2009. Net H2 surface flux, soil uptake distinct from surface emissions and finally, soil uptake, biomass burning, anthropogenic emissions and N2 fixation-related emissions separately were inverted in several scenarios. The various inversions generate an estimate for each term of the H2 budget. The net H2 flux per region (High Northern Hemisphere, Tropics and High Southern Hemisphere varies between −8 and 8 Tg yr−1. The best inversion in terms of fit to the observations combines updated prior surface emissions and a soil deposition velocity map that is based on soil uptake measurements. Our estimate of global H2 soil uptake is −59 ± 4.0 Tg yr−1. Forty per cent of this uptake is located in the High Northern Hemisphere and 55% is located in the Tropics. In terms of surface emissions, seasonality is mainly driven by biomass burning emissions. The inferred European anthropogenic emissions are consistent with independent H2 emissions estimated using a H2/CO mass ratio of 0.034 and CO emissions considering their respective uncertainties. To constrain a more robust partition of H2 sources and sinks would need additional constraints, such as isotopic measurements.

  4. Inter-observer variation in delineation of the heart and left anterior descending coronary artery in radiotherapy for breast cancer

    DEFF Research Database (Denmark)

    Lorenzen, Ebbe L.; Taylor, Carolyn W.; Maraldo, Maja;

    2013-01-01

    BACKGROUND AND PURPOSE: To determine the extent of inter-observer variation in delineation of the heart and left anterior descending coronary artery (LADCA) and its impact on estimated doses. METHODS AND MATERIALS: Nine observers from five centres delineated the heart and LADCA on fifteen patient...

  5. The Transiting System GJ1214: High-Precision Defocused Transit Observations and a Search for Evidence of Transit Timing Variation

    DEFF Research Database (Denmark)

    Harpsøe, Kennet Bomann West; Hardis, S.; Hinse, T. C.;

    2012-01-01

    Aims: We present 11 high-precision photometric transit observations of the transiting super-Earth planet GJ1214b. Combining these data with observations from other authors, we investigate the ephemeris for possible signs of transit timing variations (TTVs) using a Bayesian approach. Methods: The...

  6. OA01.22. Quality aspect and variability observed in physico-chemical characteristics and mineral content of ayurvedic herbo mineral formulations from Indian market

    OpenAIRE

    Shukla, Pankaj; Pawar, R. M; ,

    2012-01-01

    Purpose: Quality aspect and variability observed in physico-chemical characteristics and mineral content of ayurvedic herbomineral formulations from indian market w.r.t brihat vat chintamani rasa. Method: Each of the selected herbomineral formulation was thoroughly investigated for the variation in packaging material, label information, analytical parameters like moisture, pH, ash and mineral content such as Iron, Mercury, Gold, Copper and Zinc which play a crucial role in increasing the bioa...

  7. Constraining the Variation of the Fine-structure Constant with Observations of Narrow Quasar Absorption Lines

    Science.gov (United States)

    Songaila, A.; Cowie, L. L.

    2014-10-01

    The unequivocal demonstration of temporal or spatial variability in a fundamental constant of nature would be of enormous significance. Recent attempts to measure the variability of the fine-structure constant α over cosmological time, using high-resolution spectra of high-redshift quasars observed with 10 m class telescopes, have produced conflicting results. We use the many multiplet (MM) method with Mg II and Fe II lines on very high signal-to-noise, high-resolution (R = 72, 000) Keck HIRES spectra of eight narrow quasar absorption systems. We consider both systematic uncertainties in spectrograph wavelength calibration and also velocity offsets introduced by complex velocity structure in even apparently simple and weak narrow lines and analyze their effect on claimed variations in α. We find no significant change in α, Δα/α = (0.43 ± 0.34) × 10-5, in the redshift range z = 0.7-1.5, where this includes both statistical and systematic errors. We also show that the scatter in measurements of Δα/α arising from absorption line structure can be considerably larger than assigned statistical errors even for apparently simple and narrow absorption systems. We find a null result of Δα/α = (- 0.59 ± 0.55) × 10-5 in a system at z = 1.7382 using lines of Cr II, Zn II, and Mn II, whereas using Cr II and Zn II lines in a system at z = 1.6614 we find a systematic velocity trend that, if interpreted as a shift in α, would correspond to Δα/α = (1.88 ± 0.47) × 10-5, where both results include both statistical and systematic errors. This latter result is almost certainly caused by varying ionic abundances in subcomponents of the line: using Mn II, Ni II, and Cr II in the analysis changes the result to Δα/α = (- 0.47 ± 0.53) × 10-5. Combining the Mg II and Fe II results with estimates based on Mn II, Ni II, and Cr II gives Δα/α = (- 0.01 ± 0.26) × 10-5. We conclude that spectroscopic measurements of quasar absorption lines are not yet capable of

  8. Constraining the variation of the fine-structure constant with observations of narrow quasar absorption lines

    Energy Technology Data Exchange (ETDEWEB)

    Songaila, A.; Cowie, L. L., E-mail: acowie@ifa.hawaii.edu [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)

    2014-10-01

    The unequivocal demonstration of temporal or spatial variability in a fundamental constant of nature would be of enormous significance. Recent attempts to measure the variability of the fine-structure constant α over cosmological time, using high-resolution spectra of high-redshift quasars observed with 10 m class telescopes, have produced conflicting results. We use the many multiplet (MM) method with Mg II and Fe II lines on very high signal-to-noise, high-resolution (R = 72, 000) Keck HIRES spectra of eight narrow quasar absorption systems. We consider both systematic uncertainties in spectrograph wavelength calibration and also velocity offsets introduced by complex velocity structure in even apparently simple and weak narrow lines and analyze their effect on claimed variations in α. We find no significant change in α, Δα/α = (0.43 ± 0.34) × 10{sup –5}, in the redshift range z = 0.7-1.5, where this includes both statistical and systematic errors. We also show that the scatter in measurements of Δα/α arising from absorption line structure can be considerably larger than assigned statistical errors even for apparently simple and narrow absorption systems. We find a null result of Δα/α = (– 0.59 ± 0.55) × 10{sup –5} in a system at z = 1.7382 using lines of Cr II, Zn II, and Mn II, whereas using Cr II and Zn II lines in a system at z = 1.6614 we find a systematic velocity trend that, if interpreted as a shift in α, would correspond to Δα/α = (1.88 ± 0.47) × 10{sup –5}, where both results include both statistical and systematic errors. This latter result is almost certainly caused by varying ionic abundances in subcomponents of the line: using Mn II, Ni II, and Cr II in the analysis changes the result to Δα/α = (– 0.47 ± 0.53) × 10{sup –5}. Combining the Mg II and Fe II results with estimates based on Mn II, Ni II, and Cr II gives Δα/α = (– 0.01 ± 0.26) × 10{sup –5}. We conclude that spectroscopic measurements of

  9. Constraining the variation of the fine-structure constant with observations of narrow quasar absorption lines

    International Nuclear Information System (INIS)

    The unequivocal demonstration of temporal or spatial variability in a fundamental constant of nature would be of enormous significance. Recent attempts to measure the variability of the fine-structure constant α over cosmological time, using high-resolution spectra of high-redshift quasars observed with 10 m class telescopes, have produced conflicting results. We use the many multiplet (MM) method with Mg II and Fe II lines on very high signal-to-noise, high-resolution (R = 72, 000) Keck HIRES spectra of eight narrow quasar absorption systems. We consider both systematic uncertainties in spectrograph wavelength calibration and also velocity offsets introduced by complex velocity structure in even apparently simple and weak narrow lines and analyze their effect on claimed variations in α. We find no significant change in α, Δα/α = (0.43 ± 0.34) × 10–5, in the redshift range z = 0.7-1.5, where this includes both statistical and systematic errors. We also show that the scatter in measurements of Δα/α arising from absorption line structure can be considerably larger than assigned statistical errors even for apparently simple and narrow absorption systems. We find a null result of Δα/α = (– 0.59 ± 0.55) × 10–5 in a system at z = 1.7382 using lines of Cr II, Zn II, and Mn II, whereas using Cr II and Zn II lines in a system at z = 1.6614 we find a systematic velocity trend that, if interpreted as a shift in α, would correspond to Δα/α = (1.88 ± 0.47) × 10–5, where both results include both statistical and systematic errors. This latter result is almost certainly caused by varying ionic abundances in subcomponents of the line: using Mn II, Ni II, and Cr II in the analysis changes the result to Δα/α = (– 0.47 ± 0.53) × 10–5. Combining the Mg II and Fe II results with estimates based on Mn II, Ni II, and Cr II gives Δα/α = (– 0.01 ± 0.26) × 10–5. We conclude that spectroscopic measurements of quasar absorption lines are not yet

  10. Variation in sunspot properties between 1999 and 2011 as observed with the Tenerife Infrared Polarimeter

    Science.gov (United States)

    Rezaei, R.; Beck, C.; Schmidt, W.

    2012-05-01

    Aims: We study the variation in the magnetic field strength and the umbral intensity of sunspots during the declining phase of the solar cycle No. 23 and in the beginning of cycle No. 24. Methods: We analyze a sample of 183 sunspots observed from 1999 until 2011 with the Tenerife Infrared Polarimeter (TIP) at the German Vacuum Tower Telescope (VTT). The magnetic field strength is derived from the Zeeman splitting of the Stokes-V signal in one near-infrared spectral line, either Fe i 1564.8 nm, Fe i 1089.6 nm, or Si i 1082.7 nm. This avoids the effects of the unpolarized stray light from the field-free quiet Sun surroundings that can affect the splitting seen in Stokes-I in the umbra. The minimum umbral continuum intensity and umbral area are also measured. Results: We find that there is a systematic trend for sunspots in the late stage of the solar cycle No. 23 to be weaker, i.e., to have a smaller maximum magnetic field strength than those at the start of the cycle. The decrease in the field strength with time of about 94 Gyr-1 is well beyond the statistical fluctuations that would be expected because of the larger number of sunspots close to cycle maximum (14 Gyr-1). In the same time interval, the continuum intensity of the umbra increases with a rate of 1.3 (±0.4)% of Ic yr-1, while the umbral area does not show any trend above the statistical variance. Sunspots in the new cycle No. 24 show higher field strengths and lower continuum intensities than those at the end of cycle No. 23, interrupting the trend. Conclusions: Sunspots have an intrinsically weaker field strength and brighter umbrae at the late stages of solar cycles compared to their initial stages, without any significant change in their area. The abrupt increase in field strength in sunspots of the new cycle suggests that the cyclic variations are dominating over any long-term trend that continues across cycles. We find a slight decrease in field strength and an increase in intensity as a long

  11. Small vs. Large Convective Cloud Objects from CERES Aqua Observations: Where are the Intraseasonal Variation Signals?

    Science.gov (United States)

    Xu, Kuan-Man

    2016-01-01

    During inactive phases of Madden-Julian oscillation (MJO), there are plenty of deep but small convective systems and far fewer deep and large ones. During active phases of MJO, a manifestation of an increase in the occurrence of large and deep cloud clusters results from an amplification of large-scale motions by stronger convective heating. This study is designed to quantitatively examine the roles of small and large cloud clusters during the MJO life cycle. We analyze the cloud object data from Aqua CERES observations for tropical deep convective (DC) and cirrostratus (CS) cloud object types according to the real-time multivariate MJO index. The cloud object is a contiguous region of the earth with a single dominant cloud-system type. The size distributions, defined as the footprint numbers as a function of cloud object diameters, for particular MJO phases depart greatly from the combined (8-phase) distribution at large cloud-object diameters due to the reduced/increased numbers of cloud objects related to changes in the large-scale environments. The medium diameter corresponding to the combined distribution is determined and used to partition all cloud objects into "small" and "large" groups of a particular phase. The two groups corresponding to the combined distribution have nearly equal numbers of footprints. The medium diameters are 502 km for DC and 310 km for cirrostratus. The range of the variation between two extreme phases (typically, the most active and depressed phases) for the small group is 6-11% in terms of the numbers of cloud objects and the total footprint numbers. The corresponding range for the large group is 19-44%. In terms of the probability density functions of radiative and cloud physical properties, there are virtually no differences between the MJO phases for the small group, but there are significant differences for the large groups for both DC and CS types. These results suggest that the intreseasonal variation signals reside at the

  12. Ionospheric variations in the period range of days to tens of days deduced from HF doppler observation

    International Nuclear Information System (INIS)

    The HF Doppler frequency variation of the ionosphere corresponds to ionospheric phase path change, which should be ascribed to traveling ionospheric disturbance, solar flares (UV and X-ray), magnetic pulsation, geomagnetic sudden commencement as well as sudden impulse. Therefore, the HF Doppler variation may possibly be a manifestation of solar-terrestrial activity. In this paper, the results of the spectral analysis of ionospheric variation in the period ranging from a few days to tens of days observed by the HFD method in nearly the whole year of 1986 are reported. For the purpose of comparison, the spectral analysis has been done on the of F2 data and the horizontal component data of the geomagnetic field, which were obtained during the same observation period. The present study is the first long period study concerning the spectral features of HFD variation. The observation and the data, the spectral analysis and the results are reported. The most important factor for dealing with HFD records is the frequency stability of the observation system. The HFD observation detected surely ionospheric variation in the period of 3 - 13 days and 16 - 21 days. (K.I.)

  13. Ionospheric variations in the period range of days to tens of days deduced from HF doppler observation

    Energy Technology Data Exchange (ETDEWEB)

    Shibata, Takashi; Yoshimura, Yasuo; Okuzawa, Takashi (University of Electro-Communications, Chofu, Tokyo (Japan)); Ogawa, Toshio

    1989-01-01

    The HF Doppler frequency variation of the ionosphere corresponds to ionospheric phase path change, which should be ascribed to traveling ionospheric disturbance, solar flares (UV and X-ray), magnetic pulsation, geomagnetic sudden commencement as well as sudden impulse. Therefore, the HF Doppler variation may possibly be a manifestation of solar-terrestrial activity. In this paper, the results of the spectral analysis of ionospheric variation in the period ranging from a few days to tens of days observed by the HFD method in nearly the whole year of 1986 are reported. For the purpose of comparison, the spectral analysis has been done on the of F2 data and the horizontal component data of the geomagnetic field, which were obtained during the same observation period. The present study is the first long period study concerning the spectral features of HFD variation. The observation and the data, the spectral analysis and the results are reported. The most important factor for dealing with HFD records is the frequency stability of the observation system. The HFD observation detected surely ionospheric variation in the period of 3 - 13 days and 16 - 21 days. (K.I.).

  14. Photometric observations of three high mass X-ray binaries and a search for variations induced by orbital motion

    International Nuclear Information System (INIS)

    We searched for long period variation in V-band, IC-band and RXTE X-ray light curves of the High Mass X-ray Binaries (HMXBs) LS 1698 / RX J1037.5-5647, HD 110432 / 1H 1249-637 and HD 161103 / RX J1744.7-2713 in an attempt to discover orbitally induced variation. Data were obtained primarily from the ASAS database and were supplemented by shorter term observations made with the 24- and 40-inch ANU telescopes and one of the robotic PROMPT telescopes. Fourier peri-odograms suggested the existence of long period variation in the V-band light curves of all three HMXBs, however folding the data at those periods did not reveal convincing periodic variation. At this point we cannot rule out the existence of long term V-band variation for these three sources and hints of longer term variation may be seen in the higher precision PROMPT data. Long term V-band observations, on the order of several years, taken at a frequency of at least once per week and with a precision of 0.01 mag, therefore still have a chance of revealing long term variation in these three HMXBs.

  15. Seasonal variations of antimicrobial activity and chemical composition of essential oils extracted from three Citrus limon L. Burm. cultivars.

    Science.gov (United States)

    Settanni, L; Randazzo, W; Palazzolo, E; Moschetti, M; Aleo, A; Guarrasi, V; Mammina, C; San Biagio, P L; Marra, F P; Moschetti, G; Germanà, M A

    2014-01-01

    In order to investigate the seasonal variations of antimicrobial properties and chemical composition of essential oils (EOs), three different cultivars of Citrus limon L. Burm. spp. (Femminello Santa Teresa, Monachello and Femminello Continella) were collected at 6-week intervals, from December 2012 to April 2013, for a total of four harvests. The EOs were extracted from lemon peel by hydro-distillation. The antimicrobial activity, tested by paper disc diffusion method, was evaluated against common food-related pathogenic bacteria (Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica and Enterobacter spp.). EOs were more effective against Gram-positive than Gram-negative bacteria at each collection time, but a strong strain dependence was evidenced. Monachello EOs showed the highest inhibition power. The chemical characterisation of the EOs performed by gas chromatography/mass spectrometry identified from 36 to 42 molecules. The chemical difference registered among samples and seasons may explain the different antimicrobial efficacies recorded. PMID:24443967

  16. Chemical Aspects of Astrophysically Observed Extraterrestrial Methanol, Hydrocarbon Derivatives, and Ions.

    Science.gov (United States)

    Olah, George A; Mathew, Thomas; Prakash, G K Surya; Rasul, Golam

    2016-02-10

    Astrophysically observed extraterrestrial molecular matter contains, besides hydrogen and water, methane and methanol as the most abundant species. Feasible pathways and chemical aspects of their formation as well as of derived hydrocarbon homologues and their ions (carbocations and carbanions) are discussed on the basis of observed similarities with our studied terrestrial chemistry. The preferred pathway for converting extraterrestrial methane according to Ali et al. is based on CH5(+) and Olah's related nonclassical carbonium ion chemistry. On the basis of the observed higher reactivity of methanol compared with methane in various chemical reactions, a feasible new pathway is proposed for the conversion of extraterrestrial methanol to hydrocarbons, their derivatives, and carbocations together with a possible connection with methonium ion-based chemistry. PMID:26760052

  17. Mercury's thermo-chemical evolution from numerical models constrained by Messenger observations

    Science.gov (United States)

    Tosi, N.; Breuer, D.; Plesa, A. C.; Wagner, F.; Laneuville, M.

    2012-04-01

    The Messenger spacecraft, in orbit around Mercury for almost one year, has been delivering a great deal of new information that is changing dramatically our understanding of the solar system's innermost planet. Tracking data of the Radio Science experiment yielded improved estimates of the first coefficients of the gravity field that permit to determine the normalized polar moment of inertia of the planet (C/MR2) and the ratio of the moment of inertia of the mantle to that of the whole planet (Cm/C). These two parameters provide a strong constraint on the internal mass distribution and, in particular, on the core mass fraction. With C/MR2 = 0.353 and Cm/C = 0.452 [1], interior structure models predict a core radius as large as 2000 km [2], leaving room for a silicate mantle shell with a thickness of only ~ 400 km, a value significantly smaller than that of 600 km usually assumed in parametrized [3] as well as in numerical models of Mercury's mantle dynamics and evolution [4]. Furthermore, the Gamma-Ray Spectrometer measured the surface abundance of radioactive elements, revealing, besides uranium and thorium, the presence of potassium. The latter, being moderately volatile, rules out traditional formation scenarios from highly refractory materials, favoring instead a composition not much dissimilar from a chondritic model. Considering a 400 km thick mantle, we carry out a large series of 2D and 3D numerical simulations of the thermo-chemical evolution of Mercury's mantle. We model in a self-consistent way the formation of crust through partial melting using Lagrangian tracers to account for the partitioning of radioactive heat sources between mantle and crust and variations of thermal conductivity. Assuming the relative surface abundance of radiogenic elements observed by Messenger to be representative of the bulk mantle composition, we attempt at constraining the degree to which uranium, thorium and potassium are concentrated in the silicate mantle through a broad

  18. Short-term biological variation of clinical chemical values in Dumeril's monitors (Varanus dumerili).

    Science.gov (United States)

    Bertelsen, Mads F; Kjelgaard-Hansen, Mads; Howell, Jennifer R; Crawshaw, Graham J

    2007-06-01

    Plasma biochemical values are routinely used in the medical management of ill reptiles, and for monitoring the health of clinically normal animals. Laboratory tests, including clinical biochemical values, are subject to biological and analytical variation, the magnitude of which determines the utility of population-based reference ranges for the detection of abnormal results in the individual animal. Nested analysis of variance of repeated measurements allows the variance to be broken into within-individual, between-individual, and analytical variation. When the within-individual variation is large and the interindividual variation is low, a sample may be accurately classified as normal or abnormal based on a population-based reference interval. However, if the intraindividual variation is low and the interindividual variation high, population-based reference intervals are of limited value as the ranges for an individual encompass only a part of the conventional reference interval. Between-lizard, within-lizard, and analytical components of variance were assessed by nested analysis of variance for 16 commonly measured plasma biochemical parameters in eight healthy adult Dumeril's monitors (Varanus dumerili). Albumin, cholesterol, phosphate, calcium, sodium, and total protein demonstrated levels of individuality suggesting that comparison of a single measurement to a conventional population-based reference range may be too insensitive to detect small but significant alterations in the value for that animal. Only for potassium and AST did the index of individuality suggest that the use of reference values may be warranted. Uric acid, globulin, glucose, and amylase fell in a gray zone, where population-based ranges should be used with caution. The critical difference indicates the difference between two consecutive analytical results that may be safely ascribed to natural variation. In the present study critical difference varied from 7 and 11%, respectively, for

  19. VLT-UVES observations of the Balmer line variations of eta Carinae during the 2003 spectroscopic event

    OpenAIRE

    Weis, Kerstin; Stahl, Otmar; Bomans, Dominik J.; Davidson, Kris; Gull, Theodore R.; Humphreys, Roberta M.

    2004-01-01

    We present high spectral resolution echelle observations of the Balmer line variations during the 2003.5 ``spectroscopic event'' of eta Carinae. Spectra have been recorded of both eta Carinae and the Homunculus at the FOS4 position in its SE lobe. This spot shows a reflected stellar spectrum which is less contaminated by nebular emission lines than ground-based observations of the central object itself. Our observations show that the spectroscopic event is much less pronounced at this positio...

  20. Chemical Defense of the Eastern Newt (Notophthalmus viridescens): Variation in Efficiency against Different Consumers and in Different Habitats

    OpenAIRE

    Marion, Zachary H.; Hay, Mark E.

    2011-01-01

    Amphibian secondary metabolites are well known chemically, but their ecological functions are poorly understood—even for well-studied species. For example, the eastern newt (Notophthalmus viridescens) is a well known secretor of tetrodotoxin (TTX), with this compound hypothesized to facilitate this salamander's coexistence with a variety of aquatic consumers across the eastern United States. However, this assumption of chemical defense is primarily based on observational data with low replica...

  1. Human-Induced Climate Variations Linked to Urbanization: From Observations to Modeling

    Science.gov (United States)

    Shepherd, J. Marshall; Jin, Menglin

    2004-01-01

    The goal of this session is to bring together scientists from interdisciplinary backgrounds to discuss the data, scientific approaches and recent results focusing on the impact of urbanization on the climate. The discussion will highlight current observational and modeling capabilities being employed for investigating the urban environment and its linkage to the change in the Earth's climate system. The goal of the session is to identify our current stand and the future direction on the topic. Urbanization is one of the extreme cases of land use change. Most of population of the world has moved to urban areas. By 1995, more than 70% of population of North America and Europe were living in cities. By 2025, the United Nations estimates that 60% of the worlds population will live in cities. Although currently only 1.2% of the land is urban, better understanding of how the atmosphere-ocean-land-biosphere components interact as a coupled system and the influence of human activities on this system is critical. Our understanding of urbanization effect is incomplete, partly because human activities induce new changes on climate in addition to the original natural variations, and partly because previously few data available for study urban effect globally. Urban construction changes surface roughness, albedo, heat capacity and vegetation coverage. Traffic and industry increase atmospheric aerosol. It is suggested that urbanization may modify rainfall processes through aerosol-cloud interactions or dynamic feedbacks. Because urbanization effect on climate is determined by many factors including land cover, the city's microscale features, population density, and human lifestyle patterns, it is necessary to study urban areas over globe.

  2. Tracing non-conservative mass transfer eras in close binaries from observed period variations

    Science.gov (United States)

    Nanouris, N.; Kalimeris, A.; Antonopoulou, E.; Rovithis-Livaniou, H.

    2013-09-01

    The pure information directly taken from the observed orbital evolution of eclipsing binary stars (centuries at most) is valuable for the study of many important physical mechanisms related to the stellar structure. Especially in the case of eclipsing binary systems, this may happen by monitoring their eclipse timing variations, i.e. by means of an O-C diagram analysis. As long as a binary system attains a semi-detached configuration, material begins to flow from the component that fills its Roche lobe toward its mate through the first Lagrangian (L1) point. Here, we examine two non conservative mass transfer (MT) paths. The MT process is then accompanied by mass and angular momentum loss from the system. In the first path, angular momentum is removed through a hot spot which re-emits part of the incoming material, and in the second, angular momentum is carried away via an outer Lagrangian point (L2/L3) due to the small accumulating efficiency of the accretion disk surrounding the gainer. Dealing with the less massive component as the donor in the latter path, it is shown that there is always a critical mass ratio over which the period is expected to decrease, contrary to what the fully conservative MT predicts. Consistent with our expectations, the critical values become progressively smaller as the degree of liberalism is gradually widened. The O-C diagram of several semi-detached systems, expecting to experience a liberal era, is individually examined aiming to estimate both the mass transfer and the mass loss rate.

  3. Spatial and Temporal Variations in Titan's Surface Temperatures from Cassini CIRS Observations

    Science.gov (United States)

    Cottini, V.; Nixon, C. A.; Jennings, D. E.; deKok, R.; Teanby, N. A.; Irwin, P. G. J.; Flasar, F. M.

    2012-01-01

    We report a wide-ranging study of Titan's surface temperatures by analysis of the Moon's outgoing radiance through a spectral window in the thermal infrared at 19 mm (530/cm) characterized by lower atmospheric opacity. We begin by modeling Cassini Composite Infrared Spectrometer (CIRS) far infrared spectra collected in the period 2004-2010, using a radiative transfer forward model combined with a non-linear optimal estimation inversion method. At low-latitudes, we agree with the HASI near-surface temperature of about 94 K at 101S (Fulchignoni et al., 2005). We find a systematic decrease from the equator toward the poles, hemispherically asymmetric, of approx. 1 K at 60 deg. south and approx. 3 K at 60 deg. north, in general agreement with a previous analysis of CIRS data and with Voyager results from the previous northern winter. Subdividing the available database, corresponding to about one Titan season, into 3 consecutive periods, small seasonal changes of up to 2 K at 60 deg N became noticeable in the results. In addition, clear evidence of diurnal variations of the surface temperatures near the equator are observed for the first time: we find a trend of slowly increasing temperature from the morning to the early afternoon and a faster decrease during the night. The diurnal change is approx. 1.5 K, in agreement with model predictions for a surface with a thermal inertia between 300 and 600 J/ sq. m s (exp -1/2) / K. These results provide important constraints on coupled surface-atmosphere models of Titan's meteorology and atmospheric dynamic.

  4. Evolutionary analysis of genetic variation observed in citrus tristeza virus (CTV) after host passage.

    Science.gov (United States)

    Sentandreu, V; Castro, J A; Ayllón, M A; Rubio, L; Guerri, J; González-Candelas, F; Moreno, P; Moya, A

    2006-05-01

    We have studied the genetic variability in two genes (p18 and p20) from two groups of Citrus tristeza virus (CTV) isolates. One group (isolates T385, T317, T318, and T305) was derived from a Spanish source by successive host passages while the other (isolates T388 and T390) was obtained after aphid transmission from a Japanese source. A total of 274 sequences were obtained for gene p18 and 451 for p20. In the corresponding phylogenetic trees, sequences derived from the severe isolates (T318, T305, and T388) clustered together and separately from those derived from mild or moderate isolates (T385, T317, and T390), regardless of their geographic origin. Hierarchical analyses of molecular variance showed that up to 53% of the total genetic variability in p18 and up to 87% of the variation in p20 could be explained by differences in the pathogenicity features of the isolates. Neutrality tests revealed that different selection forces had been acting between isolates and between genes, with purifying selection being suggested for p18 from isolates T385 and T390 and for p20 from isolates T385, T317, and T388, and balancing selection for p18 from isolates T318, T305, and T388 and for p20 from isolates T318 and T390. Furthermore, several models of codon selection were observed, with purifying selection being the most notable one, compatible with low effective population size of the virus populations resulting from transmission bottlenecks. We found no evidence of recombination playing a significant role during p18 and p20 evolution in these isolates. These results suggest that hosts can be an important evolutionary factor for CTV isolates. PMID:16329002

  5. Seasonal variations in heat and carbon dioxide fluxes observed over a reed wetland in northeast China

    Science.gov (United States)

    Li, Xiaolan; Jia, Qingyu; Liu, Jingmiao

    2016-02-01

    Seasonal variations in sensible heat flux (Hs), latent heat flux (LE), and CO2 flux (Fc) during 2006 over a reed wetland ecosystem in Northeast China, as well as their relationships with environmental factors, were investigated based on micrometeorological observations and turbulence data, measured using the eddy covariance technique. The results showed that the LE values were significantly larger (>400 W m-2) in summer (June, July, and August) than those in other seasons because of the summertime abundant precipitation and strong evapotranspiration, whereas the Hs values were smaller (300 W m-2) and autumn (>200 W m-2). The cumulative evapotranspiration in 2006 was 577.1 mm that was mostly controlled by radiation at surface throughout the whole year but also limited by water supply during the non-growing season. Most of the Fc values ranged between -1.0 mg m-2 s-1 (sometimes close to -2.0 mg m-2 s-1) during daytime and 0.3 mg m-2 s-1 at night during the growing season (May to September) but varied around zero in the non-growing season, and the CO2 mass concentration was in the range of 600-800 mg m-3. Monthly cumulative CO2 flux for the growing season was negatively largest in July (-520 mg m-2 month-1) and smallest in May (-65 mg m-2 month-1), making this reed wetland a net CO2 sink in 2006. The daytime CO2 flux in the growing season was positively correlated with atmospheric stability |z/L| under unstable condition, photosynthetically active radiation (PAR), and wind speed, but depended less on air temperature, relative humidity and soil water content on a several-day time scale. However, over a longer time scale, a comparison of March-April conditions during 2005 and 2006 suggested that cooler conditions can result in reduced CO2 production before the growing season.

  6. Variational assimilation of land surface temperature observations for enhanced river flow predictions

    Science.gov (United States)

    Ercolani, Giulia; Castelli, Fabio

    2016-04-01

    Data assimilation (DA) has the potential of improving hydrologic forecasts. However, many issues arise in case it is employed for spatially distributed hydrologic models that describes processes in various compartments: large dimensionality of the inverse problem, layers governed by different equations, non-linear and discontinuous model structure, complex topology of domains such as surface drainage and river network.On the other hand, integrated models offer the possibility of improving prediction of specific states by exploiting observations of quantities belonging to other compartments. In terms of forecasting river discharges, and hence for their enhancement, soil moisture is a key variable, since it determines the partitioning of rainfall into infiltration and surface runoff. However, soil moisture measurements are affected by issues that could prevent a successful DA and an actual improvement of discharge predictions.In-situ measurements suffer a dramatic spatial scarcity, while observations from satellite are barely accurate and provide spatial information only at a very coarse scale (around 40 km).Hydrologic models that explicitly represent land surface processes of coupled water and energy balance provide a valid alternative to direct DA of soil moisture.They gives the possibility of inferring soil moisture states through DA of remotely sensed Land Surface Temperature (LST), whose measurements are more accurate and with a higher spatial resolution in respect to those of soil moisture. In this work we present the assimilation of LST data in a hydrologic model (Mobidic) that is part of the operational forecasting chain for the Arno river, central Italy, with the aim of improving flood predictions. Mobidic is a raster based, continuous in time and distributed in space hydrologic model, with coupled mass and energy balance at the surface and coupled groundwater and surface hydrology. The variational approach is adopted for DA, since it requires less

  7. Tides and lake-level variations in the great Patagonian lakes: Observations, modelling and geophysical implications.

    Science.gov (United States)

    Marderwald, Eric; Richter, Andreas; Horwath, Martin; Hormaechea, Jose Luis; Groh, Andreas

    2016-04-01

    In Patagonia, the glacial-isostatic adjustment (GIA) to past ice-mass changes (Ivins & James 2004; Klemann et al. 2007) is of particular interest in the context of the determination of the complex regional rheology related to plate subduction in a triple-junction constellation. To further complicate the situation, GIA is overlaid with load deformation not only due to present ice mass changes but also due to water-level changes in the lakes surrounding the icefields and the ocean surrounding Patagonia. These elastic deformations affect the determination of glacial-isostatic uplift rates from GPS observations (Dietrich et al. 2010; Lange et al. 2014). Observations of lake tides and their comparison with the theoretical tidal signal have been used previously to validate predictions of ocean tidal loading and have revealed regional deviations from conventional global elastic earth models (Richter et al. 2009). In this work we investigate the tides and lake-level variations in Lago Argentino, Lago Viedma, Lago San Martín/O'Higgins and Lago Buenos Aires/General Carrera. This allows us to test, among other things, the validity of tidal loading models. We present pressure tide-gauge records from two sites in Lago Argentino extending over 2.5 years (Richter et al. 2015). These observations are complemented by lake-level records provided by the Argentine National Hydrometeorological Network. Based on these lake-level time series the principal processes affecting the lake level are identified and quantified. Lake-level changes reflecting variations in lake volume are dominated by a seasonal cycle exceeding 1 m in amplitude. Lake-volume changes occur in addition with a daily period in response to melt water influx from surrounding glaciers. In Lago Argentino sporadic lake-volume jumps are caused by bursting of the ice dam of Perito Moreno glacier. Water movements in these lakes are dominated by surface seiches reaching 20 cm in amplitude. A harmonic tidal analysis of the lake

  8. Ultrafast electron diffraction and direct observation of transient structures in a chemical reaction

    OpenAIRE

    Cao, Jianming; Ihee, Hyotcherl; Zewail, Ahmed H.

    1999-01-01

    Ultrafast electron diffraction is a unique method for the studies of structural changes of complex molecular systems. In this contribution, we report direct ultrafast electron diffraction study of the evolution of short-lived intermediates in the course of a chemical change. Specifically, we observe the transient intermediate in the elimination reaction of 1,2-diiodotetrafluoroethane (C2F4I2) to produce the corresponding ethylene derivative by the breakage of two carbon-iodine, C---I, bonds. ...

  9. Variational density matrices in quantum field theory at finite temperature and chemical potential

    International Nuclear Information System (INIS)

    I evaluate the Helmholtz free energy of finite temperature λ var-phi 4 theory, both real and complex, using a variational quadratic ansatz for the density matrix. Minimizing with respect to the variational parameters produces results identical to those obtained by summing the daisy and superdaisy diagrams. In the nonrelativistic limit this is equivalent to a Hartree-Fock mean field with an effective mass. Quartic terms are then included by means of a relativistic generalization of the hypernetted-chain approximation without exchange terms, called the open-quote open-quote direct approximation.close-quote close-quote In this way infinite groups of rings and ladders are summed, giving nonperturbative expressions for the internal energy and four-point function in terms of a small number of Dyson-like integral equations. An expression is obtained for the internal energy of a zero-temperature system in terms of only two variational parameters. Because the hypernetted-chain approximation preserves the Euler-Lagrange variational principle, minimizing the internal energy with respect to these parameters should provide a semiquantitative upper bound on the ground state energy of an interacting relativistic system at zero temperature. For the full finite temperature theory in the direct approximation, there are now three variational parameters and it is necessary to obtain the entropy in a approximation comparable to that for the internal energy. This is done in an analogous manner to the separability approximation of nonrelativistic hypernetted-chain theory. Finally, an improvement on the direct approximation is attained by including exchange terms of all types. This proceeds along the lines of parquet summations, resulting in a set of integral equations that, when solved self-consistently, includes all series and parallel connections of direct and exchange diagrams. copyright 1996 The American Physical Society

  10. Variation in chemical composition and acaricidal activity against Dermanyssus gallinae of four eucalyptus essential oils.

    Science.gov (United States)

    George, David R; Masic, Dino; Sparagano, Olivier A E; Guy, Jonathan H

    2009-06-01

    The results of this study suggest that certain eucalyptus essential oils may be of use as an alternative to synthetic acaricides in the management of the poultry red mite, Dermanyssus gallinae. At a level of 0.21 mg/cm(2), the essential oil from Eucalyptus citriodora achieved 85% mortality in D. gallinae over a 24 h exposure period in contact toxicity tests. A further two essential oils from different eucalyptus species, namely E. globulus and E. radiata, provided significantly (P eucalyptus essential oils regarding their chemical compositions. There appeared to be a trend whereby the essential oils that were composed of the fewer chemical components were the least lethal to D. gallinae. It may therefore be the case that the complexity of an essential oil's chemical make up plays an important role in dictating the toxicity of that oil to pests such as D. gallinae. PMID:19089590

  11. Ratio variation of electron capture probability to positron decay probability for 68Ga in chemical compounds

    International Nuclear Information System (INIS)

    The change of 68 Ga gamma-line intensities in different chemical compounds is studied.Electron capture (EC) competes with 68 Ga β+ decay. The effect of chemical environment on the probabilities of these processes is different. Radioactive sources are prepared in the form of GeS and GeO2 compounds with 68 Ge (T1/2=288 days; the decay is due to EC with 68Ga formation in the ground state). The measured value of intensity change δI/I for 68 Ga in GeS relative to GeO equals (11+-3)x10-4

  12. Correlated analysis of chemical variations with spectroscopic features of the K-Na jarosite solid solutions relevant to Mars

    Science.gov (United States)

    Ling, Zongcheng; Cao, Fengke; Ni, Yuheng; Wu, Zhongchen; Zhang, Jiang; Li, Bo

    2016-06-01

    Detailed chemical, structural and spectroscopic properties of jarosite solid solution minerals are key information for their potential discoveries by future remote sensing and in-situ detections on Mars. We successfully synthesized seven homogeneous K-Na jarosite solid solutions under hydrothermal conditions at 140 °C, whose phase identifications and chemical compositions are confirmed by X-ray diffraction (XRD) and inductively coupled plasma mass spectrometry (ICP-MS). The chemical ratios of K/(K+Na) in jarosite solid solutions lead to systematic shifts of their characteristic Raman peaks ν1 (SO4)2- (from 1006 to 1011.3 cm-1), ν3 (SO4)2- (from 1100.6 to 1111.2 cm-1), ν2 (SO4)2- (from 434.2 to 444.8 cm-1) with the increase of Na content. While the OH stretching mode decreases with even larger peak position variations (e.g., ∼3410 cm-1 peak shifts from 3410.5 to 3385.7 cm-1) as the K-Na jarosite solid solutions are enriched in Na content. Raman spectroscopic measurements of the seven K-Na jarosite solid solutions enabled us to build a calibration that uses Raman peak positions to estimate K-Na variation in jarosite, which is the key step for their possible applications in the future Raman applications on Mars' missions (e.g., ExoMars and Mars 2020 missions). The band assignments and compositional related variations of their XRD, near-infrared (NIR) and mid-infrared (MIR) spectra also provide informative clues for identifying the jarosite minerals and inferring their composition during martian in-situ and remote sensing measurements.

  13. Spacebased Observations of Oceanic Influence on the Annual Variation of South American Water Balance

    Science.gov (United States)

    Liu, W. Timothy; Xie, Xiaosu; Tang, Wenqing; Zlotnicki, Victor

    2006-01-01

    The mass change of South America (SA) continent measured by the Gravity Recovery and Climate Experiment (GRACE) imposes a constraint on the uncertainties in estimating the annual variation of rainfall measured by Tropical Rain Measuring Mission (TRMM) and ocean moisture influx derived from QuikSCAT data. The approximate balance of the mass change rate with the moisture influx less climatological river discharge, in agreement with the conservation principle, bolsters not only the credibility of the spacebased measurements, but supports the characterization of ocean's influence on the annual variation of continental water balance. The annual variation of rainfall is found to be in phase with the mass change rate in the Amazon and the La Plata basins, and the moisture advection across relevant segments of the Pacific and Atlantic coasts agrees with the annual cycle of rainfall in the two basins and the Andes mountains.

  14. Chemical Variation in a Dominant Tree Species: Population Divergence, Selection and Genetic Stability across Environments

    OpenAIRE

    Julianne M O'Reilly-Wapstra; Miller, Alison M.; Hamilton, Matthew G.; Dean Williams; Naomi Glancy-Dean; Potts, Brad M.

    2013-01-01

    Understanding among and within population genetic variation of ecologically important plant traits provides insight into the potential evolutionary processes affecting those traits. The strength and consistency of selection driving variability in traits would be affected by plasticity in differences among genotypes across environments (G×E). We investigated population divergence, selection and environmental plasticity of foliar plant secondary metabolites (PSMs) in a dominant tree species, Eu...

  15. Probing variations in fundamental constants with radio and optical quasar absorption-line observations

    CERN Document Server

    Tzanavaris, P; Webb, J K; Flambaum, V V; Curran, S J

    2006-01-01

    Nine quasar absorption spectra at 21-cm and UV rest-wavelengths are used to estimate possible variations in x=alpha^2 g_p mu, (alpha is the fine structure constant, g_p the proton g-factor and mu=me/mp the electron-to-proton mass ratio). We find ^weighted_total(=Dxxwt)=(0.63+-0.99) 10^-5 over 0.23~variation yields strong limits on the variation of mu. Our most conservative estimate, obtained by assuming no variations in alpha or g_p is Delta mu/mu(=Dmm)=Dxxwt. If we use only the four high-redshift absorbers in our sample, we obtain Dmm=(0.58+-...

  16. A method for direct variational data assimilation from various observing systems

    Science.gov (United States)

    Penenko, Vladimir V.

    2015-11-01

    A new method for the joint use of mathematical models and heterogeneous data from various monitoring systems for ground and space based assets, including the sequence of images, is presented. The method is based on variational principles with weak constraints. The algorithm for its implementation allows us to use images in the problems of prediction and reconstruction of multidimensional fields of the state functions.

  17. Variation in weed infestation of sugar beet (Beta vulgaris L. subsp. vulgaris depending on the intensity of chemical protection of plantations

    Directory of Open Access Journals (Sweden)

    Krzysztof Domaradzki

    2014-07-01

    Full Text Available A floristic study was conducted over the period 2010–2012, using the Braun-Blanquet method, under which vegetation relevés were made in sugar beet (Beta vulgaris L. subsp. vulgaris plantations in Lower Silesia. Fields with similar habitat conditions, which differed in the intensity of herbicide application to control weed infestation, were selected for observation. A total of 144 relevés were made and based on them a list was prepared of species found in fields in which different levels of chemical protection were used. A cover index and a constancy class were determined for each species found in the phytocoenoses studied. On the basis of these observations, the study found floristic  variation in the investigated agrophytocenoses as af- fected by the level of intensity of weed control chemicals used. In  herbicide-untreated plots, a total of 25 weed species were found and their aggregate cover index was 8705. Chenopodium album L., Polygonum persicaria L. and Setaria pumila (POIR. ROEM. & SCHULT by far dominated among them. Herbicide use caused an impoverishment in the floristic list. 20 taxa were observed in the plots treated with the lowest herbicide rates, while with increasing rates the number of species dropped to 18. The sum of the cover indices also decreased with increasing rates, successively reaching the values of 5907, 5212 and 4356.

  18. variations of the atmospheric chemical composition in the earths's polar regions after solar proton flare on July 14, 2000 (photochemical simulation)

    Science.gov (United States)

    Kukoleva, A. A.; Krivolutsky, A. A.; Ondraskova, A.

    2010-02-01

    Altitude—temporal cross-sections q( z, t) of atmospheric ionization rates by solar protons above the polar regions were calculated using the GOES-10 satellite data on solar proton fluxes for the period of solar proton flare (SPF) on July 14, 2000. The values of q( z, t) were used further in calculations of variations of the atmospheric chemical composition during the flare in the northern and southern polar regions (70°N and 70°S) by two different 1D photochemical models of the atmosphere (neutral and charged components). The calculation results have shown considerable variation of the ozone content after SPF: a decrease of [O3] was about 80% at altitudes of 65-75 km above northern and 25% in the layer of 55-65 km above the southern polar region. Such decrease of the ozone content is a result of reactions with [NO] and [OH] whose concentrations have grown substantially during SPF. According to calculations, the increase of electron concentration during SPF has reached 3-4 orders of magnitude at altitudes of 50-80 km. A comparison of the calculation results with the observational data on [NO], [NO2], and [O3] from the UARS and HALOE satellites for 70°N have shown a good qualitative correspondence, however, for variations of nitric oxides there are quantitative discrepancies.

  19. Inter-relationships between Bacteriological and Chemical Variations in Lake Pamvotis—Greece

    OpenAIRE

    Kagalou, I.; Tsimarakis, G.; Bezirtzoglou, E.

    2011-01-01

    The relationships between indicator bacteria and the organic load were conducted over a year in Lake Pamvotis, in northwest Greece. Total coliforms (TC) and fecal coliforms (FC) were found in water samples from five different sampling stations. Organic load was estimated using biological oxygen demand (BOD) and chemical oxygen demand (COD) parameters. Increased TC and FC levels were found close to heavily polluted areas. Near-bottom samples had higher levels of bacteria and the numbers of TC ...

  20. Exclusion of cosmic rays in protoplanetary disks. II. Chemical gradients and observational signatures

    Energy Technology Data Exchange (ETDEWEB)

    Cleeves, L. Ilsedore; Bergin, Edwin A.; Adams, Fred C. [Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109 (United States)

    2014-10-20

    The chemical properties of protoplanetary disks are especially sensitive to their ionization environment. Sources of molecular gas ionization include cosmic rays (CRs), stellar X-rays, and short-lived radionuclides, each of which varies with location in the disk. This behavior leads to a significant amount of chemical structure, especially in molecular ion abundances, which is imprinted in their submillimeter rotational line emission. Using an observationally motivated disk model, we make predictions for the dependence of chemical abundances on the assumed properties of the ionizing field. We calculate the emergent line intensity for abundant molecular ions and simulate sensitive observations with the Atacama Large Millimeter/Sub-millimeter Array (ALMA) for a disk at D = 100 pc. The models readily distinguish between high ionization rates (ζ ≳ 10{sup –17} s{sup –1} per H{sub 2}) and below, but it becomes difficult to distinguish between low ionization models when ζ ≲ 10{sup –19} s{sup –1}. We find that H{sub 2}D{sup +} emission is not detectable for sub-interstellar CR rates with ALMA (6h integration), and that N{sub 2}D{sup +} emission may be a more sensitive tracer of midplane ionization. HCO{sup +} traces X-rays and high CR rates (ζ{sub CR} ≳ 10{sup –17} s{sup –1}), and provides a handle on the warm molecular ionization properties where CO is present in the gas. Furthermore, species like HCO{sup +}, which emits from a wide radial region and samples a large gradient in temperature, can exhibit ring-like emission as a consequence of low-lying rotational level de-excitation near the star. This finding highlights a scenario where rings are not necessarily structural or chemical in nature, but simply a result of the underlying line excitation properties.

  1. Exclusion of cosmic rays in protoplanetary disks. II. Chemical gradients and observational signatures

    International Nuclear Information System (INIS)

    The chemical properties of protoplanetary disks are especially sensitive to their ionization environment. Sources of molecular gas ionization include cosmic rays (CRs), stellar X-rays, and short-lived radionuclides, each of which varies with location in the disk. This behavior leads to a significant amount of chemical structure, especially in molecular ion abundances, which is imprinted in their submillimeter rotational line emission. Using an observationally motivated disk model, we make predictions for the dependence of chemical abundances on the assumed properties of the ionizing field. We calculate the emergent line intensity for abundant molecular ions and simulate sensitive observations with the Atacama Large Millimeter/Sub-millimeter Array (ALMA) for a disk at D = 100 pc. The models readily distinguish between high ionization rates (ζ ≳ 10–17 s–1 per H2) and below, but it becomes difficult to distinguish between low ionization models when ζ ≲ 10–19 s–1. We find that H2D+ emission is not detectable for sub-interstellar CR rates with ALMA (6h integration), and that N2D+ emission may be a more sensitive tracer of midplane ionization. HCO+ traces X-rays and high CR rates (ζCR ≳ 10–17 s–1), and provides a handle on the warm molecular ionization properties where CO is present in the gas. Furthermore, species like HCO+, which emits from a wide radial region and samples a large gradient in temperature, can exhibit ring-like emission as a consequence of low-lying rotational level de-excitation near the star. This finding highlights a scenario where rings are not necessarily structural or chemical in nature, but simply a result of the underlying line excitation properties.

  2. Relation between the short-term variation of the Jovian radiation belt and thermosphere derived from radio and infrared observations

    Science.gov (United States)

    Kita, Hajime; Misawa, Hiroaki; Bhardwaj, Anil; Tsuchiya, Fuminori; Sakanoi, Takeshi; Kasaba, Yasumasa; Tao, Chihiro; Miyoshi, Yoshizumi; Morioka, Akira

    2015-08-01

    We report the first comprehensive observations of Jovian synchrotron radiation (JSR) and H3+ emission from the Jovian thermosphere to investigate the generation process of short-term (days to weeks) variations in the Jovian radiation belt. The observations were made by the Giant Metrewave Radio Telescope and NASA Infrared Telescope Facility during November 2011. The total flux density of JSR increased by approximately 5% between 6-9 November and 12-17 November, associated with the increased solar UV/EUV flux. From 7 to 14 November, a possible rise in the infrared H3+ emission was observed in the middle-latitude region, corresponding to a temperature variation of approximately 10 K. These results are consistent with the scenario that the solar UV/EUV heating causes variations in the thermospheric temperature and JSR. Radio images along the equatorial region showed that the JSR intensity decreased inside 1.5 Jovian radii (RJ) and the peak position shifted outward. This implies that energetic electrons are attenuated by some internal loss process, despite the simultaneous increase in radial diffusion. A physical model for the radiation belt shows that such an internal loss process can explain the observed variation of brightness distribution. Typical loss time scale is longer than strong diffusion limit, which suggests the existence of some pitch angle diffusion process such as wave-particle interaction. Thus, variations of the total JSR flux density and thermospheric temperature seem consistent with the scenario, and the brightness distribution of JSR can be explained by the increase in radial diffusion accompanied by internal loss processes.

  3. Evaluation of Predicted and Observed Data on Biotransformation of Twenty-Nine Trace Organic Chemicals

    KAUST Repository

    Bertolini, Maria

    2011-07-01

    Trace organic chemicals present in household products, pesticides, pharmaceuticals and personal care products may have adverse ecotoxicological effects once they are released to the environment. These chemicals are usually transported with the sewage to wastewater treatment facilities, where they might be attenuated depending on the degree of treatment applied prior to discharge to receiving streams. This study evaluates the removal performance of 29 trace organic compounds during two different activated sludge treatment systems. Predominant attenuation processes such as biotransformation and sorption for the target compounds were identified. Biotransformation rate constants determined in this study were used to assess removal of compounds from other treatment plants with similar operational conditions, using data gathered from the literature. The commercial software Catalogic was applied to predict environmental fate of chemicals. The software program consisted of four models able to simulate molecular transformations and to generate degradation trees. In order to assess the accuracy of this program in predicting biotransformation, one biodegradation model is used to contrast predicted degradation pathway with metabolic pathways reported in the literature. The predicted outcome was correct for more than 40 percent of the 29 targeted substances, while 38 percent of the chemicals exhibited some degree of lower agreement between predicted and observed pathways. Percent removal data determined for the two treatment facilities was compared with transformation probability output from Catalogic. About 80 percent of the 29 compounds exhibited a good correlation between probability of transformation of the parent compound and percent removal data from the two treatment plants (R2 = 0.82 and 0.9). Based upon findings for 29 trace organic chemicals regarding removal during activated sludge treatment, attacked fragments present in their structures, predicted data from

  4. Observing seasonal variations of sea surface wind speed and significant wave height using TOPEX altimetry

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    One year of ocean topography experiment (TOPEX) altimeter data are used to study the seasonal variations of global sea surface wind speed and significant wave height. The major wind and wave zones of the world oceans are precisely identified, their seasonal variability and characteristics are quantitatively analyzed, and the diversity of global wind speed seasonality and the variability of significant wave height in response to sea surface wind speed are also revealed.

  5. Interstellar Extinction Curve Variations Toward the Inner Milky Way: A Challenge to Observational Cosmology

    CERN Document Server

    Nataf, David M; Casagrande, Luca; Zasowski, Gail; Wegg, Christopher; Wolf, Christian; Kunder, Andrea; Alonso-Garcia, Javier; Minniti, Dante; Rejkuba, Marina; Saito, Roberto K; Valenti, Elena; Zoccali, Manuela; Poleski, Radoslaw; Pietrzynski, Grzegorz; Skowron, Jan; Soszynski, Igor; Szymanski, Michal K; Udalski, Andrzej; Ulaczyk, Krzystof; Wyrzykowski, Lukasz

    2015-01-01

    We investigate interstellar extinction curve variations toward $\\sim$4 deg$^{2}$ of the inner Milky Way in $VIJK_{s}$ photometry from the OGLE-III and $VVV$ surveys, with supporting evidence from diffuse interstellar bands and $F435W,F625W$ photometry. We obtain independent measurements toward $\\sim$2,000 sightlines of $A_{I}$, $E(V-I)$, $E(I-J)$, and $E(J-K_{s})$, with median precision and accuracy of 2%. We find that the variations in the extinction ratios $A_{I}/E(V-I)$, $E(I-J)/E(V-I)$ and $E(J-K_{s})/E(V-I)$ are large (exceeding 20%), significant, and positively correlated, as expected. However, both the mean values and the trends in these extinction ratios are drastically shifted from the predictions of Cardelli and Fitzpatrick, regardless of how $R_{V}$ is varied. Furthermore, we demonstrate that variations in the shape of the extinction curve has at least two degrees of freedom, and not one (e.g. $R_{V}$), which we conform with a principal component analysis. We derive a median value of $=13.44$, whic...

  6. A NEW CHEMICAL EVOLUTION MODEL FOR DWARF SPHEROIDAL GALAXIES BASED ON OBSERVED LONG STAR FORMATION HISTORIES

    International Nuclear Information System (INIS)

    We present a new chemical evolution model for dwarf spheroidal galaxies (dSphs) in the local universe. Our main aim is to explain both their observed star formation histories and metallicity distribution functions simultaneously. Applying our new model for the four local dSphs, that is, Fornax, Sculptor, Leo II, and Sextans, we find that our new model reproduces the observed chemical properties of the dSphs consistently. Our results show that the dSphs have evolved with both a low star formation efficiency and a large gas outflow efficiency compared with the Milky Way, as suggested by previous works. Comparing the observed [α/Fe]-[Fe/H] relation of the dSphs with the model predictions, we find that our model favors a longer onset time of Type Ia supernovae (i.e., 0.5 Gyr) than that suggested in previous studies (i.e., 0.1 Gyr). We discuss the origin of this discrepancy in detail

  7. Assessment of MODIS sun-sensor geometry variations effect on observed NDVI using MSG SEVIRI geostationary data

    DEFF Research Database (Denmark)

    Fensholt, R.; Sandholt, I.; Proud, Simon Richard;

    2010-01-01

    -sensor geometry variations will have a more visible impact on the Normalized Difference Vegetation Index (NDVI) from MODIS compared to earlier data sources, since noise related to atmosphere and sensor calibration is substantially reduced in the MODIS data stream. For this reason, the effect of varying MODIS...... cloud cover for three consecutive years (2004-2006). An analysis covering the entire range of NDVI revealed day-to-day variations in observed MODIS NDVI of 50-60% for medium dense vegetation (NDVI approximate to 0.5) caused by variations in MODIS view zenith angles (VZAs) between nadir and the high...... reflectances depends on the amount of vegetation present. MODIS VZA and RAA effects on NDVI were highest for medium dense vegetation (NDVI approximate to 0.5-0.6). The VZA and RAA effects were less for sparsely vegetated areas (NDVI approximate to 0.3-0.35) and the smallest effect on NDVI was found for dense...

  8. Seasonal variation in the chemical composition and carbohydrate signature compounds of biofilm

    Digital Repository Service at National Institute of Oceanography (India)

    DeSouza, F.P.; Garg, A.; Bhosle, N.B.

    :N and organic carbon:chlorophyll a ratios decreased over the period of immersion. Despite the abundance of microalgal biomass, carbohydrate concentration was lower than that observed for proteins. Carbohydrate composition varied during the period of immersion...

  9. Variation of atmospheric tritium concentration in three chemical forms at Toki, Japan: 2004-12.

    Science.gov (United States)

    Tanaka, M; Uda, T

    2015-11-01

    Atmospheric tritium concentrations of HTO, HT and CH3T have been measured at Toki, Japan, for the environmental impact assessment of tritium for a fusion test facility. According to the data from 2004 to 2012, the concentrations of HT and HTO in water vapour tend to increase in spring. The seasonal variation in HT concentration at Toki was compared with the H2 concentration between 1990 and 2005 at Tae-ahn Peninsula, Republic of Korea, which is at approximately the same latitude as Toki. The monthly average of HT-specific activity varied from 1.24 × 10(5) to 1.76 × 10(5) TU. The peak of the monthly average H2 concentration did not match that of HT. This indicates that the mechanism of the production or the source of HT might be different from the production mechanism of H2. PMID:25935005

  10. Variation of atmospheric tritium concentration in three chemical forms at Toki, Japan: 2004-12

    International Nuclear Information System (INIS)

    Atmospheric tritium concentrations of HTO, HT and CH3T have been measured at Toki, Japan, for the environmental impact assessment of tritium for a fusion test facility. According to the data from 2004 to 2012, the concentrations of HT and HTO in water vapour tend to increase in spring. The seasonal variation in HT concentration at Toki was compared with the H2 concentration between 1990 and 2005 at Tae-ahn Peninsula, Republic of Korea, which is at approximately the same latitude as Toki. The monthly average of HT-specific activity varied from 1.24 x 105 to 1.76 x 105 TU. The peak of the monthly average H2 concentration did not match that of HT. This indicates that the mechanism of the production or the source of HT might be different from the production mechanism of H2. (authors)

  11. Chemical composition and seasonal variation of the volatile oils from leaves of Michelia champaca L., Magnoliaceae

    Directory of Open Access Journals (Sweden)

    João Henrique G. Lago

    2009-12-01

    Full Text Available The volatile oils from leaves of Michelia champaca L. collected bimonthly during one year (four times on the fifteenth day of January, March, May, July, September, and November - 2004 were subjected to GC/FID and GC-MS analysis, from which thirteen components were identified. Additionally, part of the oil obtained from January collection was subjected to fractionation over silica gel soaked with AgNO3 to afford five of the main sesquiterpenes (β-elemene, β-caryophyllene, α-humulene, β-selinene, and α-cadinol. The obtained data showed a significative variation in the proportions of the components, which could be associated to climatic parameters in each collection periods.

  12. Variation of chemical composition of essential oils in wild populations of Thymus algeriensis Boiss. et Reut., a North African endemic Species

    Directory of Open Access Journals (Sweden)

    Zouari Nacim

    2012-02-01

    Full Text Available Abstract Background Thymus algeriensis is an endemic aromatic plant to Tunisia largely used in folk medicine and as a culinary herb. The bulks aromatic plants come from wild populations whose essential oils compositions as well as their biological properties are severely affected by the geographical location and the phase of the plant development. Therefore, the aim of the present work is to provide more information on the variation of essential oil composition of T. algeriensis collected during the vegetative and the flowering phases and from eight different geographical regions. Besides, influence of population location and phenological stage on yield and metal chelating activity of essential oils is also assessed. Methods The essential oil composition of Thymus algeriensis was determined mainly by GC/FID and GC/MS. The chemical differentiation among populations performed on all compounds was assessed by linear discriminate analysis and cluster analysis based on Euclidean distance. Results A total of 71 compounds, representing 88.99 to 99.76% of the total oil, were identified. A significant effect of the population location on the chemical composition variability of T. algeriensis oil was observed. Only 18 out of 71 compounds showed a statistically significant variation among population locations and phenological stages. Chemical differentiation among populations was high. Minor compounds play an important role to distinguish between chemical groups. Five chemotypes according to the major compounds have been distinguished. Chemotypes distribution is linked to the population location and not to bioclimate, indicating that local selective environmental factors acted on the chemotype diversity. Conclusions The major compounds at the species level were α-pinene (7.41-13.94%, 1,8-cineole (7.55-22.07%, cis-sabinene hydrate (0.10-12.95%, camphor (6.8-19.93%, 4-terpineol (1.55-11.86%, terpenyl acetate (0-14.92% and viridiflorol (0-11.49%. Based on

  13. Validation of Predicted Diurnal and Semi-diurnal Tidal Variations in Polar Motion with GPS-based Observations

    Science.gov (United States)

    Desai, Shailen; Sibois, Aurore

    2016-04-01

    In this paper we reconcile predicted diurnal and semi-diurnal tidal variations in polar motion using observations from the Global Positioning System (GPS) space geodetic technique. We demonstrate closure at the level of less than 4 microarcseconds of the budget between our adopted models for predicted polar motion tidal variations and our GPS-based observations. Our GPS-based observations are composed of a 10-year continuous time series of polar motion estimates with 15-minute temporal resolution. Our adopted models account for the contribution from the relative angular momentum of the ocean tides and so-called libration. We compute predicted ocean tide contributions using a modern hydrodynamic model of tide heights and currents that assimilates satellite altimetry data. We use the model for libration effects provided by the current IERS conventions, as taken from Mathews and Bretagnon [2003]. We also show that the currently recommended models from the International Earth Rotation Service (IERS) conventions do not close the budget with respect to our GPS-based observations. In particular, residual diurnal and semidiurnal tidal variations in polar motion are observed when using the current IERS conventions for ocean tide effects and libration. We infer that the root source for these residual tidal variations is errors in the 20-year old model for ocean tide effects from the IERS conventions, and that predicted ocean tide effects from a modern model mitigates these errors. The noise floor of our high-rate GPS-based times series of polar motion is less than 4 microarcseconds in the diurnal and semidiurnal tidal frequency bands, and is well below the level of the predicted effects of both the ocean tide and libration effects. Diurnal and semidiurnal tidal variations in polar motion are predominantly caused by the ocean tides, which have amplitudes of a few hundred microarcseconds. Libration, namely the effect of external luni-solar torques acting on the triaxial Earth

  14. SEASONAL VARIATION IN PHYSICO-CHEMICAL PARAMETERS OF THE HARWA JABBAR JHEEL OF KATIHAR, BIHAR

    Directory of Open Access Journals (Sweden)

    Mahalakshmi Kumari

    2014-12-01

    Full Text Available Water is the important component for life and for rural development. The Katihar district of Bihar is one of the important districts from Agricultural point of view. The Harwa Jabbar Jheel is a natural depression of 180 ha and depth 40ft. the present study was made to study the physico-chemical status of the Jheel from fisheries point of view. The study revealed that air temperature 28.05± 4.32 water temperature25.06±4.67 the pH 7.09±0.26 dissolved oxygen 6.35±1.18 free carbon dioxide 20.75±10.11 and total alkalinity 127.16±11.62. It is concluded that above parameters of the Jheel is within favorable range for fish culture.

  15. Kinetics of methane fermentation yield in biogas reactors: Genetic variation and association with chemical composition in maize

    International Nuclear Information System (INIS)

    Maize (Zea mays L.) is the most competitive crop for methane production in Germany. Methane fermentation yield per unit of dry matter (MFY) is a determinant of methane yield, but little information is available on this trait. Our objectives were to investigate the kinetics of MFY during fermentation of maize, estimate quantitative-genetic parameters for different traits related to MFY and examine the relationship of MFY with chemical composition and silage quality. Whole-plant material of 16 inbreds and their 32 testcrosses was analyzed for MFY over 35 days of fermentation using a discontinuous laboratory assay. Data were also generated on chemical composition and in vitro digestible organic matter (IVDOM). Significant genotypic variances and high heritabilities were observed for MFY at early fermentation stages (up to 5 days) probably due to different concentrations of easily degradable chemical components. However, genotypic variances and heritability of MFY reduced as fermentation progressed, because of complete or partial degradation of all chemical components. Further, there were strong correlations of MFY with chemical components at early fermentation stages but not at later stages. Therefore, MFY at later stages, which is closer to potential MFY, does not seem to be amenable to selection. High heritability of IVDOM and its strong correlation with MFY in testcrosses indicated its possible use for preliminary or indirect selection. Keeping in view the magnitude of genetic variance that was low for MFY and high for dry matter yield (DMY), the other component of methane yield, more emphasis on breeding for DMY seems appropriate. -- Highlights: ► We investigated methane fermentation yield (MFY) of diverse germplasm of maize. ► The kinetics of MFY and its correlations with chemical composition were examined. ► Genetic variance and heritability for MFY decreased with fermentation time. ► Complete fermentation (35 d) reduced correlations of MFY with chemical

  16. Ionospheric variations in the period range of days to tens of days deduced from HF Doppler observation

    Science.gov (United States)

    Shibata, Takashi; Yoshimura, Yasuo; Okuzawa, Takashi; Ogawa, Toshio

    Ionospheric variations in the period range of a few days to tens of days observed by the HF Doppler (HFD) method for the entire year of 1986 have been investigated by a spectrum analysis. The crystal oscillator employed has a stability of up 5 x 10 to the -9th/day at the primary stage of 5 MHz. The present method was shown to be capable of detecting ionospheric variations in the period range of both 3 to about 13 days and 16 to about 21 days. It is suggested that a 27-day period was not observed in both the HFD and the foF2 spectra due to minimum solar activity.

  17. Ionospheric Variations in the Region of the Equatorial Ionization Anomaly Crest: Comparison Between Observations and IRI-2012 Model Predictions.

    Science.gov (United States)

    Oyeyemi, E. O.; Bolaji, S.; Adewale, A. O.; Akala, A. O.; Oladipo, O. A.; Olugbon, B.; Olawepo, O. A.; Adeniyi, J. O.; Adimula, I.

    2015-12-01

    The objective of this work is to study the variations of the F2-layer critical frequency (foF2) in the region of equatorial ionization anomaly crest and check the accuracy of International Reference Ionosphere (IRI-2012) model predictions using ionosonde measurements from a number of stations in this region. We have used data, based on availability, corresponding to different seasonal and solar activity periods from each station considered to carry out our investigations. Details of the statistical analysis using percentage deviation (PD), upper and lower inter-quartile range (IQR) and relative deviation module mean (RDMM) for the evaluation of the IRI model performance are presented. The results show that, generally, the IRI model predictions have agreement with the observed values in terms of the pattern of variations but there are number of cases where IRI model overestimates and underestimates the observed values. Results from this study will be of help to improving prediction ability of the IRI models.

  18. First Observation of Time Variation in the Solar-Disk Gamma-Ray Flux with Fermi

    CERN Document Server

    Ng, Kenny C Y; Peter, Annika H G; Rott, Carsten

    2015-01-01

    The solar disk is a bright gamma-ray source. Surprisingly, its flux is about one order of magnitude higher than predicted. As a first step toward understanding the physical origin of this discrepancy, we perform a new analysis in 1-100 GeV using 6 years of public Fermi-LAT data. Compared to the previous analysis by the Fermi Collaboration, who analyzed 1.5 years of data and detected the solar disk in 0.1-10 GeV, we find two new and significant results: 1. In the 1-10 GeV flux (detected at $>5\\sigma$), we discover a significant time variation that anticorrelates with solar activity. 2. We detect gamma rays in 10- 30 GeV at $>5\\sigma$, and in 30- 100 GeV at $> 2\\sigma$. The time variation strongly indicates that solar-disk gamma rays are induced by cosmic rays and that solar atmospheric magnetic fields play an important role. Our results provide essential clues for understanding the underlying gamma-ray production processes, which may allow new probes of solar atmospheric magnetic fields, cosmic rays in the sol...

  19. Spatial Variations of the Extinction Law in the Galactic Disk from Infrared Observations

    CERN Document Server

    Gontcharov, George

    2016-01-01

    Infrared photometry in the J (1.2 microns), H (1.7 microns), Ks (2.2 microns) bands from the 2MASS catalogue and in the W1 (3.4 microns), W2 (4.6 microns), W3 (12 microns), W4 (22 microns) bands from the WISE catalogue is used to reveal the spatial variations of the interstellar extinction law in the infrared near the midplane of the Galaxy by the method of extrapolation of the extinction law applied to clump giants. The variations of the coefficients E(H-W1)/E(H-Ks), E(H-W2)/E(H-Ks), E(H-W3)/E(H-Ks), and E(H-W4)/E(H-Ks) along the line of sight in 2 deg per 2 deg squares of the sky centered at b=0 and l=20, 30, ..., 330, 340 deg as well as in several 4 deg per 4 deg squares with |b|=10 are considered. The results obtained here agree with those obtained by Zasowski et al. in 2009 using 2MASS and Spitzer-IRAC photometry for the same longitudes and similar photometric bands, confirming their main result: in the inner (relative to the Sun) Galactic disk, the fraction of fine dust increases with Galactocentric dis...

  20. Variations in water storage in China over recent decades from GRACE observations and GLDAS

    Science.gov (United States)

    Mo, X.; Wu, J. J.; Wang, Q.; Zhou, H.

    2016-02-01

    We applied Gravity Recovery and Climate Experiment (GRACE) Tellus products in combination with Global Land Data Assimilation System (GLDAS) simulations and data from reports, to analyze variations in terrestrial water storage (TWS) in China as a whole and eight of its basins from 2003 to 2013. Amplitudes of TWS were well restored after scaling, and showed good correlations with those estimated from models at the basin scale. TWS generally followed variations in annual precipitation; it decreased linearly in the Huai River basin (-0.56 cm yr-1) and increased with fluctuations in the Changjiang River basin (0.35 cm yr-1), Zhujiang basin (0.55 cm yr-1) and southeast rivers basin (0.70 cm yr-1). In the Hai River basin and Yellow River basin, groundwater exploitation may have altered TWS's response to climate, and TWS kept decreasing until 2012. Changes in soil moisture storage contributed over 50 % of variance in TWS in most basins. Precipitation and runoff showed a large impact on TWS, with more explained TWS in the south than in the north. North China and southwest rivers region exhibited long-term TWS depletions. TWS has increased significantly over recent decades in the middle and lower reaches of Changjiang River, southeastern coastal areas, as well as the Hoh Xil, and the headstream region of the Yellow River in the Tibetan Plateau. The findings in this study could be helpful to climate change impact research and disaster mitigation planning.

  1. First observation of time variation in the solar-disk gamma-ray flux with Fermi

    Science.gov (United States)

    Ng, Kenny C. Y.; Beacom, John F.; Peter, Annika H. G.; Rott, Carsten

    2016-07-01

    The solar disk is a bright gamma-ray source. Surprisingly, its flux is about 1 order of magnitude higher than predicted. As a first step toward understanding the physical origin of this discrepancy, we perform a new analysis in 1-100 GeV using 6 years of public Fermi-LAT data. Compared to the previous analysis by the Fermi Collaboration, which analyzed 1.5 years of data and detected the solar disk in 0.1-10 GeV, we find two new and significant results: (1) In the 1-10 GeV flux (detected at >5 σ ), we discover a significant time variation that anticorrelates with solar activity, and (2) we detect gamma rays in 10-30 GeV at >5 σ and in 30-100 GeV at >2 σ . The time variation strongly indicates that solar-disk gamma rays are induced by cosmic rays and that solar atmospheric magnetic fields play an important role. Our results provide essential clues for understanding the underlying gamma-ray production processes, which may allow new probes of solar atmospheric magnetic fields, cosmic rays in the solar system, and possible new physics. Finally, we show that the Sun is a promising new target for ground-based TeV gamma-ray telescopes such as HAWC and LHAASO.

  2. Variations in water storage in China over recent decade from GRACE Observations and GLDAS

    Directory of Open Access Journals (Sweden)

    X. Mo

    2015-05-01

    Full Text Available We applied GRACE Tellus products in combination with GLDAS simulations and data from reports, to analyze variations in terrestrial water storage (TWS in China and eight of its basins from 2003 to 2013. Amplitudes of TWS were well restored after scaling, and showed good correlations with those estimated from models at the basin scale. TWS generally followed variations in annual precipitation, it decreased linearly in Huai River basin (−0.564 cm yr−1 and increased with fluctuations in Changjiang River basin (0.348 cm yr−1, Zhujiang basin (0.552 cm yr−1 and Southeast Rivers basin (0.696 cm yr−1. In Hai River basin and Yellow River basin, groundwater exploitation may have altered TWS's response to climate, but it began to restore since 2012. Changes in soil moisture storage contributed over 50% in of variances in TWS in most basins. Precipitation and runoff showed large impact on TWS, with explained variances higher in TWS in the south than in the north. North China and Southwest Rivers region exhibited long-term TWS depletions. TWS increased significantly over the recent decade in the middle and lower reaches of Changjiang, southeastern coastal area, as well as the Hoh Xil, and headstream region of the Yellow River in Tibetan plateau. The findings in this study could be helpful to climate change impact research and disaster mitigation planning.

  3. First ground-based FTIR observations of the seasonal variation of carbon monoxide in the tropics

    Science.gov (United States)

    Petersen, A. K.; Warneke, T.; Lawrence, M. G.; Notholt, J.; Schrems, O.

    2008-02-01

    We present the first ground-based solar absorption Fourier Transform Infrared (FTIR) spectrometric measurements in the inner tropics over several years. The FTIR observations agree well with satellite data from the MOPITT instrument. MATCH-MPIC model simulations reproduce the mean vertical structure of the FTIR observations. The model is generally not able to reproduce the extreme enhancements seen during the specific biomass burning events by both observation instruments. Nevertheless, the model indicates that beyond the background source of CO from methane oxidation, the main contributions to the CO mixing ratios are the episodic convective injection of NMHCs and CO from South American biomass burning into the upper troposphere, along with long range transport of African biomass burning CO, particularly during spring. In future studies with more extensive observed time series, observations such as these will be valuable for evaluating ongoing improvements in global chemistry transport models.

  4. Variation of Jupiter's aurora observed by Hisaki/EXCEED: 2. Estimations of auroral parameters and magnetospheric dynamics

    Science.gov (United States)

    Tao, Chihiro; Kimura, Tomoki; Badman, Sarah V.; André, Nicolas; Tsuchiya, Fuminori; Murakami, Go; Yoshioka, Kazuo; Yoshikawa, Ichiro; Yamazaki, Atsushi; Fujimoto, Masaki

    2016-05-01

    Jupiter's auroral parameters are estimated from observations by a spectrometer EXCEED (Extreme Ultraviolet Spectroscope for Exospheric Dynamics) on board Japanese Aerospace Exploration Agency's Earth-orbiting planetary space telescope Hisaki. EXCEED provides continuous auroral spectra covering the wavelength range over 80-148 nm from the whole northern polar region. The auroral electron energy is estimated using a hydrocarbon color ratio adopted for the wavelength range of EXCEED, and the emission power in the long wavelength range 138.5-144.8 nm is used as an indicator of total emitted power before hydrocarbon absorption and auroral electron energy flux. The quasi-continuous observations by Hisaki provide the auroral electron parameters and their relation under different auroral activity levels. Short- (within one planetary rotation) enhancements of auroral power accompany increases of the electron number flux rather than the electron energy variations. The relationships between the auroral electron energy (~70-400 keV) and flux (1026-1027/s, 0.08-0.9 μA/m2) estimated from the observations over a 40 day interval are in agreement with field-aligned acceleration theory when incorporating probable magnetospheric parameters. Applying the electron acceleration theory to each observation point, we explore the magnetospheric source plasma variation during these power-enhanced events. Possible scenarios to explain the derived variations are (i) an adiabatic variation of the magnetospheric plasma under a magnetospheric compression and/or plasma injection, and (ii) a change of the dominant auroral component from the main emission (main aurora) to the emission at the open-closed boundary.

  5. Long-Term Seafloor Electromagnetic Observation in the Northwest Pacific May Detect the Vector Geomagnetic Secular Variation

    OpenAIRE

    Toh, H; Hamano, Y.; Goto, T.; Utada, H

    2010-01-01

    Sea Floor ElectroMagnetic Stations (SFEMSs) are now operating at two deep seafloor sites called the 'WPB' and the 'NWP' in the West Philippine Basin and the Northwest Pacific Basin, respectively. One of the main objectives of the SFEMSs is to detect the geomagnetic secular variations on the deep seafloor where long-term geomagnetic observations have not so far been achieved. SFEMSs can measure the absolute geomagnetic total force as well as the geomagnetic vector field with precise attitude m...

  6. Divergent variations in concentrations of chemical elements among shrub organs in a temperate desert

    Science.gov (United States)

    He, Mingzhu; Song, Xin; Tian, Fuping; Zhang, Ke; Zhang, Zhishan; Chen, Ning; Li, Xinrong

    2016-01-01

    Desert shrubs, a dominant component of desert ecosystems, need to maintain sufficient levels of nutrients in their different organs to ensure operation of various physiological functions for the purpose of survival and reproduction. In the present study, we analyzed 10 elements in leaves, stems, and roots of 24 dominant shrub species from 52 sites across a temperate desert ecosystem in northwestern China. We found that concentrations of all 10 elements were higher in leaves than in stems and roots, that non-legumes had higher levels of leaf Na and Mg than did legumes, and that Na was more concentrated in C4 leaves than in C3 leaves. Scaling relationships of elements between the photosynthetic organ (leaf) and non-photosynthetic organs (stem and root) were allometric. Results of principal components analysis (PCA) highlighted the important role of the elements responsible for osmoregulation (K and Na) in water utilization of desert shrubs. Soil properties and taxonomy explained most variation of element concentrations in desert shrubs. Desert shrubs may not be particularly susceptible to future change in climate factors, because most elements (including N, P, K, Ca, Mn, Zn, and Cu) associated with photosynthesis, osmoregulation, enzyme activity, and water use efficiency primarily depend on soil conditions.

  7. Influence of Chemical Composition Variations on Densification During the Sintering of MOX Materials

    Science.gov (United States)

    Vaudez, S.; Marlot, C.; Lechelle, J.

    2016-06-01

    The mixed uranium-plutonium oxide (MOX) fabrication process is based on the preparation of UO2 and PuO2 powders. The mixture is pelletized before being sintered at 1973 K (1700 °C) in a reducing atmosphere of Ar/4pctH2/H2O. This paper shows how the densification of MOX fuel is affected during sintering by the moisture content of the gas, the plutonium content of the fuel, and the carbon impurity content in the raw materials. MOX densification can be monitored through dilatometric measurements and gas releases can be continuously analyzed during sintering in terms of their quantity and quality. Variations in the oxygen content in the fuel can be continuously recorded by coupling the dilatometer furnace with an oxygen measurement at the gas outlet. Any carbon-bearing species released, such as CO, can be also linked to densification phenomena when a gas chromatograph is installed at the outlet of the dilatometer. Recommendations on the choice of sintering atmosphere that best optimizes the fuel characteristics have been given on the basis of the results reported in this paper.

  8. IMOS National Reference Stations: a continental-wide physical, chemical and biological coastal observing system.

    Directory of Open Access Journals (Sweden)

    Tim P Lynch

    Full Text Available Sustained observations allow for the tracking of change in oceanography and ecosystems, however, these are rare, particularly for the Southern Hemisphere. To address this in part, the Australian Integrated Marine Observing System (IMOS implemented a network of nine National Reference Stations (NRS. The network builds on one long-term location, where monthly water sampling has been sustained since the 1940s and two others that commenced in the 1950s. In-situ continuously moored sensors and an enhanced monthly water sampling regime now collect more than 50 data streams. Building on sampling for temperature, salinity and nutrients, the network now observes dissolved oxygen, carbon, turbidity, currents, chlorophyll a and both phytoplankton and zooplankton. Additional parameters for studies of ocean acidification and bio-optics are collected at a sub-set of sites and all data is made freely and publically available. Our preliminary results demonstrate increased utility to observe extreme events, such as marine heat waves and coastal flooding; rare events, such as plankton blooms; and have, for the first time, allowed for consistent continental scale sampling and analysis of coastal zooplankton and phytoplankton communities. Independent water sampling allows for cross validation of the deployed sensors for quality control of data that now continuously tracks daily, seasonal and annual variation. The NRS will provide multi-decadal time series, against which more spatially replicated short-term studies can be referenced, models and remote sensing products validated, and improvements made to our understanding of how large-scale, long-term change and variability in the global ocean are affecting Australia's coastal seas and ecosystems. The NRS network provides an example of how a continental scaled observing systems can be developed to collect observations that integrate across physics, chemistry and biology.

  9. Important chemical and physical traits and variation in these traits in 'tombul' hazelnut cultivar at different elevations

    Directory of Open Access Journals (Sweden)

    Zeki Bostan, S.

    2003-09-01

    Full Text Available This study was conducted on ‘Tombul’ hazelnut growing at four elevations (0-50 m, 100-150 m, 200-250 m and 300-350 m in Persembe (Ordu/ Northern Turkey province in 1999 and 2000 years. Sixteen traits (oil, protein and ash contents as chemical; nut weight, nut size, shell thickness, kernel weight, kernel size, percent kernel, internal cavity, shriveled kernels, good kernels as physical; pH, organic matter, phosphorus and potassium in soil were examined at each elevation. Interrelationships among important soil, nut and kernel characteristics were examined. There were significant correlation and interrelationships among the traits. The correlation between oil-nut size, oil- protein positively; protein-kernel size, protein- shriveled kernel negatively; organic matter- shell thickness, organic matter-good kernel negatively; pH- shell thickness, pH-good kernel negatively; good kernel-shell thickness positively; shriveled kernel-kernel weight, shriveled kernel-percent kernel negatively; internal cavity-nut weight positively and internal cavity-nut size negatively; percent kernel-kernel weight, percent kernel-kernel size positively; kernel size-kernel weight positively, and kernel weight-nut weight positively were significant. Significant differences among elevations were observed for shell thickness, ash content in kernel, and pH value in soil. The highest coefficients of variation were observed for phosphorus, shriveled kernels, potassium, internal cavity and organic matter, respectivelyEste estudio ha sido realizado en la avellana ’Tombul’ que crece en cuatro elevaciones (0-50 m, 100-150 m, 200-250 m y 300- 350 m en la provincia de Persembe (Ordu/ Norte de Turquía en los años 1999 y 2000. Dieciséis rasgos (contenido en aceite, proteína y ceniza como características químicas; peso, tamaño y grosor de cáscara, peso, tamaño y porcentaje del grano, cavidad interna, granos arrugados y granos buenos como características f

  10. Iodine monoxide at a clean marine coastal site: observations of high frequency variations and inhomogeneous distributions

    Directory of Open Access Journals (Sweden)

    R. Commane

    2011-07-01

    Full Text Available The first in situ point observations of iodine monoxide (IO at a clean marine site were made using a laser-induced fluorescence instrument deployed at Mace Head, Ireland in August 2007. IO mixing ratios of up to 49.8 pptv (equivalent to pmol mol−1; 1 s average were observed at day-time low tide, well in excess of previous observed spatially-averaged maxima. A strong anti-correlation of IO mixing ratios with tide height was evident and the high time resolution of the observations showed IO peaked in the hour after low tide. The temporal delay in peak IO compared to low tide has not been observed previously but coincides with the time of peak aerosol number previously observed at Mace Head.

    A long path-differential optical absorption spectroscopy instrument (with a 2 × 6.8 km folded path across Roundstone Bay was also based at the site for 3 days during the point measurement observation period. Both instruments show similar temporal trends but the point measurements of IO are a factor of ~6–10 times greater than the spatially averaged IO mixing ratios, providing direct empirical evidence of the presence of inhomogeneities in the IO mixing ratio near the intertidal region.

  11. Impacts of rice plant roots on the variation in electro-physico-chemical properties of soil waters

    International Nuclear Information System (INIS)

    Lowland rice crop is cultivated under continuous flooding and anaerobic conditions but rhizospheric region of the rice plants can have different physico-chemical conditions than in the absence of roots. However, it is very difficult to measure all physico-chemical parameters instantaneously in the rhizos phere because this region, being highly dynamic, altering rapidly those parameters of surrounding soil waters. Present study has compared the evolution of electro-physico-chemical properties (pH, redox potentials (pe), Electrical Conductivity (EC) and temperature) of soil waters during a complete day at two different phenological stages in the presence of rice roots (rhizosphere) and in the absence of roots to analyse the effect of rhizosphere on soil waters. In the rhizosphere, pH of soil waters was found comparatively low (7). Similarly, small EC values were observed in the rhizosphere. Great fluctuations (diurnal patterns) were observed during the complete days which were directly associated to atmospheric conditions (temperature and light) and rhizospheric activity, and these fluctuations were more during vegetative phase as compared to maturation stage of rice. It was also observed that incorporation of crop residues resulted in the more reductive conditions in the rice culture. (author)

  12. Seasonal variation in the physico-chemical Parameters of Tirana river

    Directory of Open Access Journals (Sweden)

    Enkelejda KUCAJ

    2015-08-01

    Full Text Available Water quality has become a major concern due to ever increasing human developmental activities that over exploit and pollute the water resources. As the Economic and financial centre of Albania, Tirana has an extensive experienced urban expansion after 1990 with a very high cost in environmental degradation The aim of the present study is to examine the water quality of Tirana River Nile through several physico-chemical analyses. Results obtained from two seasons (June-September, during 2011-2013 . Water samples were taken at different locations and indicators were analyzed: temperature, pH, DO, TDS, NBO5, NO3- , NO2 - , NH4 + , P total and PO4 3- . Based on the results of the analysis and the rates set by Albanian state standards catalogue (KSSH, 2012 has shown that the river was highly polluted due to urban and industrial effluent in the urban and the water of these river classified as class IV and V. High concentrations of NH3, total dissolved solids (TDS, biological oxygen demand (BOD, total alkalinity, turbidity and recognizable depletion in dissolved oxygen (DO were recorded. Increasing pollution and negative impact of discharges in these river ecosystems is a disturbing problem and requires constant monitoring and a final solution by treatment of these waters before pouring them into the sea.

  13. Associated chemical and carbon isotopic composition variations in diamonds from Finsch and Premier kimberlite, South Africa

    International Nuclear Information System (INIS)

    The carbon isotopic composition of 66 inclusion-containing diamonds from the Premier kimberlite, South Africa, 93 inclusion-containing diamonds and four diamonds of two diamond-bearing peridotite xenoliths from the Finsch kimberlite, South Africa was measured. The data suggest a relationship between the carbon isotopic composition of the diamonds and the chemical composition of the associated silicates. For both kimberlites similar trends are noted for diamonds containing peridotite-suite inclusions (P-type) and for diamonds containing eclogite-suite inclusions (E-type): Higher delta13C P-type diamonds tend to have inclusions lower in SiO2, Al2O3, Cr2O3, MgO, Mg/(Mg + Fe) and higher in FeO and CaO. Higher delta13C E-type diamonds tend to have inclusions lower in SiO2, Al2O3, MgO, Mg/(Mg + Fe), Na2O, K2O, TiO2 and higher in CaO, Ca/(Ca + Mg). Consideration of a number of different models that have been proposed for the genesis of kimberlites, their zenoliths and diamonds shows that they are all consistent with the conclusion that in the mantle, regions exist that are characterized by different mean carbon isotopic compositions. (author)

  14. Plutonic rocks of Jurassic age in the Alaska-Aleutian Range batholith: chemical variation and polarity.

    Science.gov (United States)

    Reed, B.I.; Miesch, A.T.; Lanphere, M.A.

    1983-01-01

    Plutonic rocks of Jurassic age exposed on the Pacific side of this batholith form a compositionally continuous calc-alkaline suite that ranges from hornblende gabbro to quartz monzonite. Tonalite and quartz diorite are the dominant rock types. Trend-surface analysis of 102 samples indicates that the direction of slope of the trend is approximately normal to the Jurassic magmatic arc. K2O and SiO2 increase towards the E-SE and the other oxides towards the W-NW. If the chemical trends reflect the approximate geometry of a palaeo-subduction zone, the polarity of the Jurassic magmatic arc is to the NW, i.e. subduction was directed towards the SE. Thus the palaeo-subduction zone is on the opposite side of the arc from the position that has generally been assumed, indicating that the Jurassic plutonic rocks were not generated in response to classical Andean-type convergent plate margins. The magmatic arc may have been formed in an intra-ocean environment and subsequently has been rafted northwards and accreted to this part of the N Pacific rim during the late Mesozoic. Middle and Upper Jurassic clastics underlying Cook Inlet to the SE and derived from the magmatic arc are classified as back-arc deposits, rather than as an arc-trench gap sequence.-L.C.H.

  15. Seasonal variations and chemical characteristics of PM(2.5) in Wuhan, central China.

    Science.gov (United States)

    Zhang, Fan; Wang, Zu-wu; Cheng, Hai-rong; Lv, Xiao-pu; Gong, Wei; Wang, Xin-ming; Zhang, Gan

    2015-06-15

    PM2.5 samples were collected at an urban site (WD) and a suburban site (TH) in Wuhan from August 2012 to July 2013. The mass concentrations of water-soluble inorganic ions, carbonaceous species and elements of PM2.5 were measured. The annual mean concentrations of PM2.5 were 106.5 μg/m(3) and 114.9 μg/m(3) at WD and TH, respectively. The chemical compositions of PM2.5 at WD were similar to those at TH and the fractions of the major components of PM2.5 in Wuhan were in the following order of trace elementssandstorm from north carrying abundant soil dusts in spring in China. Ten trace elements (Cu, Ga, Ag, Tl, Ca, As, Zn, Pb, Se and Cd) were enriched in PM2.5 and the higher EF for Ag, Pb, Se and Cd in PM2.5 indicated that the air pollution from vehicle exhaust emission and coal burning in Wuhan was serious and noteworthy. PMID:25747369

  16. Alkaline peroxide pulping of oil palm empty fruit bunch by variation of chemical strength

    Science.gov (United States)

    Dermawan, Yunita Megasari; Ghazali, Arniza; Daud, Wan Rosli Wan; Lazin, Mohd Azli Khairil Mat

    2012-09-01

    Papers produced from oil palm empty fruit bunches (EFB) via Alkaline Peroxide Pulping (APP) was preceded by three main steps; dewaxing of EFB, alkaline peroxide (AP) impregnation into EFB and refining of biomass to generate pulp. The experiment was carried by varying chemical level and number of impregnation stages. For 2:2.5% AP level, two-stage impregnation improved hand sheets tear index by 45%, 164% boost in tensile index, 26% enhancement in zero span index and more than 5% in burst index. By applying 8:10% AP level, significant improvements were gained at the third and fourth stages of AP impregnation. Although there was no significant change in hand sheet strength with multiple impregnation for 4:5% AP level, improvement in brightness of hand sheets was apparent, analogous to the effect of increasing AP level. The found paper properties development show that alkaline peroxide pulping of EFB could be adapted to various targeted properties by adjustment of AP level and impregnation stages.

  17. Combined assimilation of IASI and MLS observations to constrain tropospheric and stratospheric ozone in a global chemical transport model

    Directory of Open Access Journals (Sweden)

    E. Emili

    2013-08-01

    Full Text Available Accurate and temporally resolved fields of free-troposphere ozone are of major importance to quantify the intercontinental transport of pollution and the ozone radiative forcing. In this study we examine the impact of assimilating ozone observations from the Microwave Limb Sounder (MLS and the Infrared Atmospheric Sounding Interferometer (IASI in a global chemical transport model (MOdèle de Chimie Atmosphérique à Grande Échelle, MOCAGE. The assimilation of the two instruments is performed by means of a variational algorithm (4-D-VAR and allows to constrain stratospheric and tropospheric ozone simultaneously. The analysis is first computed for the months of August and November 2008 and validated against ozone-sondes measurements to verify the presence of observations and model biases. It is found that the IASI Tropospheric Ozone Column (TOC, 1000–225 hPa should be bias-corrected prior to assimilation and MLS lowermost level (215 hPa excluded from the analysis. Furthermore, a longer analysis of 6 months (July–August 2008 showed that the combined assimilation of MLS and IASI is able to globally reduce the uncertainty (Root Mean Square Error, RMSE of the modeled ozone columns from 30% to 15% in the Upper-Troposphere/Lower-Stratosphere (UTLS, 70–225 hPa and from 25% to 20% in the free troposphere. The positive effect of assimilating IASI tropospheric observations is very significant at low latitudes (30° S–30° N, whereas it is not demonstrated at higher latitudes. Results are confirmed by a comparison with additional ozone datasets like the Measurements of OZone and wAter vapour by aIrbus in-service airCraft (MOZAIC data, the Ozone Monitoring Instrument (OMI total ozone columns and several high-altitude surface measurements. Finally, the analysis is found to be little sensitive to the assimilation parameters and the model chemical scheme, due to the high frequency of satellite observations compared to the average life-time of free

  18. Observed periodicities and the spectrum of field variations in Holocene magnetic records

    DEFF Research Database (Denmark)

    Panovska, S.; Finlay, Chris; Hirt, A.M.

    2013-01-01

    techniques: multitaper spectral estimation, wavelet analysis and empirical mode decomposition. When records are grouped according to their geographical locations, we find encouraging consistency amongst the observed periods, especially in nearby inclination records. No evidence was obtained for discrete...

  19. Substorm variations in the magnitude of the magnetic field - AMPTE/CCE observations

    Science.gov (United States)

    Lopez, R. E.; Sibeck, D. G.; Lui, A. T. Y.; Takahashi, K.; Mcentire, R. W.

    1988-01-01

    Using energetic-particle data taken in the near-earth tail by the AMPTE/Charge Composition Explorer (CCE) satellite, 167 ion injection events, that were essentially dispersionless over a 25-285 keV energy range, were identified, and the variations in the total magnetic field strength over the course of these events were examined in order to determine the dependence of the magnetic field strength on dipole latitude. Results indicate that, during periods of substorm activity, the latitudinal position of the current sheet varied significantly within the 32-deg wedge centered on the dipole equator traversed by CCE. Results also suggest that, even in the near-earth magnetotail out to 8.8 R(E) (CCE apogee), the local field measurements are a better guide to the determination of satellite's position relative to the current shield during a substorm, than is the magnetic latitude.

  20. Conductivity Variation Observed by Polarization and Depolarization Current Measurements of High-Voltage Equipment Insulation System

    Science.gov (United States)

    Jamail, Nor Akmal Mohd; Piah, Mohamed Afendi Mohamed; Muhamad, Nor Asiah

    2012-09-01

    Nondestructive and time domain dielectric measurement techniques such as polarization and depolarization current (PDC) measurements have recently been widely used as a potential tool for determining high-voltage insulation conditions by analyzing the insulation conductivity. The variation in the conductivity of an insulator was found to depend on several parameters: the difference between the polarization and depolarization currents, geometric capacitance, and the relative permittivity of the insulation material. In this paper the conductivities of different types of oil-paper insulation material are presented. The insulation conductivities of several types of electrical apparatus were simulated using MATLAB. Conductivity insulation was found to be high at high polarizations and at the lowest depolarization current. It was also found to increase with increasing relative permittivity as well as with decreasing geometric capacitance of the insulating material.

  1. Inter- and intra-observer variation in classification systems for impending fractures of bone metastases

    Energy Technology Data Exchange (ETDEWEB)

    El-Husseiny, Moataz [University College London Hospitals, London (United Kingdom); Coleman, Nigel [Queen Elizabeth Hospital, King' s Lynn NHS Trust, Orthopaedics and Trauma Unit, Norfolk (United Kingdom)

    2010-02-15

    The study was designed to assess the reproducibility and reliability of Mirels' scoring system and the conventional scoring system for impending pathological fractures. The results of both classification systems influence the choice of therapeutic procedures offered to these patients. Eight independent observers (four orthopaedic surgeons and four radiologists with varying clinical experience) scored blinded plain radiographs from 47 patients with bone metastases. Each observer scored the radiographs as per the Mirels and the conventional systems. After 12 weeks, the observers scored the radiographs again. Inter- and intra-observer agreement was assessed based on the weighted kappa coefficient values for both systems. For intra-observer reproducibility, kappa values for the conventional system had a mean of 0.499 (SD 0.074) showing a moderate agreement, while Mirels' scoring system had a mean of 0.396 (SD 0.101) showing a fair agreement. For inter-observer reliability, kappa values for the conventional scoring system were 0.322 for the first test and 0.47 for the second test, giving fair and moderate agreement respectively. For Mirels' scoring system, the kappa coefficient for inter-observer reliability was 0.183 for the first test and 0.218 for the second, giving poor and fair agreement respectively. The conventional scoring system showed better inter and intra-observer agreement compared with Mirels' scoring system. Both systems fail to take into account factors such as co-morbidities and prognosis. We believe the conventional system is a good screening tool, but a new scoring system is required for impending pathological fractures. (orig.)

  2. Seasonal variations of vivax and falciparum malaria: an observation at a tertiary care hospital

    International Nuclear Information System (INIS)

    Background: Malaria is a major public health problem in the malaria endemic zones of the world. Various factors influence the prevalence of malaria. This study was conducted to determine the variation in frequency of Plasmodium vivax and Plasmodium falciparum malaria in different seasons of the year in Khyber Teaching Hospital, Peshawar. Methods: A total of 411 patients were included in the study. All these febrile patients were reported to have trophozoites of either Plasmodium vivax or Plasmodium falciparum malaria on Giemsa stained thick and thin smears. The frequency of vivax and falciparum malaria was worked out and statistically analysed for different season of the year. The study was carried out from 2nd Jan 2004 till 31st December 2008. Results: Out of total 411 diagnosed malaria cases, total 134 (32.60%) presented in the autumn season (vivax=33.58%, and falciparum=66.42%), 37 (9%) in winter season (vivax=32.4%, and falciparum=67.6%), 76 (18.49%) in spring season (vivax=93.4% and falciparum 6.6%) and 164 (39.90%) in summer season (vivax=89.6, and falciparum=10.4%). The malaria showed a highly significant pattern in different seasons of the year (p=0.00) in a way that Plasmodium falciparum malaria reached its highest frequency in autumn and winter seasons while Plasmodium vivax malaria reached its peak frequency in spring and summer seasons. Conclusion: There was highly significant seasonal variation of vivax and falciparum malaria. There is arrival of Plasmodium falciparum in autumn which peaks in winter followed by arrival of Plasmodium vivax in spring till the end of summer. (author)

  3. Solar cycle variation of interplanetary shocks, coronal mass ejections, and stream interactions observed at 0.7 AU

    Science.gov (United States)

    Lindsay, G. M.; Luhmann, J. G.; Russell, C. T.; Gazis, P.

    1995-01-01

    A survey of the Pioneer Venus Orbiter (PVO) magnetometer and plasma data from 1979-1980, shows that the occurrence frequency of interplanetary shocks, coronal mass ejections (CMEs) and stream interactions observed at 0.7 AU exhibits a solar cycle variation. As previously found at 1 AU, the observed number of both interplanetary shocks and CMEs peaks during solar maximum (approximately 16 and approximately 27 per year, respectively) and reaches a low during solar minimum (approximately 0 and approximately 7 per year, respectively), in phase with the variation in smoothed sunspot number. The number of stream interactions observed varies in the opposite manner, having a minimum during solar maximum (approximately 15 per year) and a maximum during solar minimum (approximately 34 per year). The percentage of CMEs and stream interactions producing interplanetary shocks also varies during the solar-cycle and exhibits interesting behavior during the declining phase. While the number of CMEs observed during this phase is decreasing, the percentage of CMEs producing interplanetary shocks reaches a maximum. Also, while the number of stream interactions observed is increasing, but has not reached maximum during the declining phase, the percentage of stream interactions producing interplanety shocks is at a maximum.

  4. Using ACE Observations of Interplanetary Particles and Magnetic Fields as Possible Contributors to Variations Observed at Van Allen Probes during Major events in 2013

    Science.gov (United States)

    Armstrong, T. P.; Manweiler, J. W.; Gerrard, A. J.; Gkioulidou, M.; Lanzerotti, L. J.; Patterson, J. D.

    2013-12-01

    Observations from ACE EPAM including energy spectra of protons, helium, and oxygen will be prepared for coordinated use in estimating the direct and indirect access of energetic particles to inner and outer geomagnetic trapping zones. Complete temporal coverage from ACE at 12 seconds, 5 minutes, 17 minutes, hourly and daily cadences will be used to catalog interplanetary events arriving at Earth including interplanetary magnetic field sector boundaries, interplanetary shocks, and interplanetary coronal mass ejections, ICMEs. The first 6 months of 2013 have included both highly disturbed times, March 17 and May 22, and extended quiet periods of little or no variations. Among the specific questions that ACE and Van Allen Probes coordinated observations may aid in resolving are: 1. How much, if any, direct capture of interplanetary energetic particles occurs and what conditions account for it? 2. How much influence do interplanetary field and particle variations have on energization and/or loss of geomagnetically trapped populations? The poster will also present important links and describe methods and important details of access to numerically expressed ACE EPAM and Van Allen Probes RBSPICE observations that can be flexibly and easily accessed via the internet for student and senior researcher use.

  5. Chemical defense of the eastern newt (Notophthalmus viridescens: variation in efficiency against different consumers and in different habitats.

    Directory of Open Access Journals (Sweden)

    Zachary H Marion

    Full Text Available Amphibian secondary metabolites are well known chemically, but their ecological functions are poorly understood--even for well-studied species. For example, the eastern newt (Notophthalmus viridescens is a well known secretor of tetrodotoxin (TTX, with this compound hypothesized to facilitate this salamander's coexistence with a variety of aquatic consumers across the eastern United States. However, this assumption of chemical defense is primarily based on observational data with low replication against only a few predator types. Therefore, we tested the hypothesis that N. viridescens is chemically defended against co-occurring fishes, invertebrates, and amphibian generalist predators and that this defense confers high survivorship when newts are transplanted into both fish-containing and fishless habitats. We found that adult eastern newts were unpalatable to predatory fishes (Micropterus salmoides, Lepomis macrochirus and a crayfish (Procambarus clarkii, but were readily consumed by bullfrogs (Lithobates catesbeianus. The eggs and neonate larvae were also unpalatable to fish (L. macrochirus. Bioassay-guided fractionation confirmed that deterrence is chemical and that ecologically relevant concentrations of TTX would deter feeding. Despite predatory fishes rejecting eastern newts in laboratory assays, field experiments demonstrated that tethered newts suffered high rates of predation in fish-containing ponds. We suggest that this may be due to predation by amphibians (frogs and reptiles (turtles that co-occur with fishes rather than from fishes directly. Fishes suppress invertebrate consumers that prey on bullfrog larvae, leading to higher bullfrog densities in fish containing ponds and thus considerable consumption of newts due to bullfrog tolerance of newt chemical defenses. Amphibian chemical defenses, and consumer responses to them, may be more complex and indirect than previously appreciated.

  6. SEASONAL VARIATION OF CHEMICAL COMPOSITION AND DRY MATTER DIGESTIBILITY OF RANGELANDS IN NW GREECE

    Directory of Open Access Journals (Sweden)

    I MOUNTOUSIS

    2009-03-01

    Full Text Available This study was carried out to determine the chemical composition and in vitro dry matter digestibility of grazable material, during the growing season of plants, in three different altitudinal zones, in native rangelands, northwestern Greece. Samples were collected during the period from May to October of the years 2004 and 2005. Sample collection was accomplished by cutting aboveground biomass at a height similar to that grazed by small ruminants. The results showed that herbage production was significantly affected (P<0.001 by sampling year, growing season and altitudinal zone respectively, as well as (P<0.01 by the “month x year” and (P<0.05 “altitude x month” interactions. CP, ash, EE and CF content and IVDMD affected significantly (P<0.01 by both harvest month and altitudinal zone, while there was no significant affection by the sampling year and the interaction between altitude, month and year (except EE which affected (P<0.01 by the “month x year” interaction. Herbage production strongly related (P<0.01 to the altitude (r= +0.247, harvest month (r= -0.479 and CP content (r= -0.274. IVDMD related positively (P<0.01 to CP (r= +0.729, ash (r= +0.369 and EE (r= +0.351 content and negatively to harvest month (r= -0.779 and to CF content (r= -0.663. It was recommended that additional protein sources should be supplied in order to cover the needs of the grazing animals. It is necessary the transhumance of herds from lower to higher altitude for better utilization of rangelands.

  7. Impact of observed North Atlantic multidecadal variations to European summer climate: a linear baroclinic response to surface heating

    Science.gov (United States)

    Ghosh, Rohit; Müller, Wolfgang A.; Baehr, Johanna; Bader, Jürgen

    2016-07-01

    The observed prominent multidecadal variations in the central to eastern (C-E) European summer temperature are closely related to the Atlantic multidecadal variability (AMV). Using the Twentieth Century Reanalysis project version 2 data for the period of 1930-2012, we present a mechanism by which the multidecadal variations in the C-E European summer temperature are associated to a linear baroclinic atmospheric response to the AMV-related surface heat flux. Our results suggest that over the north-western Atlantic, the positive heat flux anomaly triggers a surface baroclinic pressure response to diabatic heating with a negative surface pressure anomaly to the east of the heat source. Further downstream, this response induces an east-west wave-like pressure anomaly. The east-west wave-like response in the sea level pressure structure, to which we refer as North-Atlantic-European East West (NEW) mode, is independent of the summer North Atlantic Oscillation and is the principal mode of variations during summer over the Euro-Atlantic region at multidecadal time scales. The NEW mode causes warming of the C-E European region by creating an atmospheric blocking-like situation. Our findings also suggest that this NEW mode is responsible for the multidecadal variations in precipitation over the British Isles and north-western Europe.

  8. Impacts of trait variation through observed trait–climate relationships on performance of an Earth system model: a conceptual analysis

    Directory of Open Access Journals (Sweden)

    L. M. Verheijen

    2013-08-01

    Full Text Available In many current dynamic global vegetation models (DGVMs, including those incorporated into Earth system models (ESMs, terrestrial vegetation is represented by a small number of plant functional types (PFTs, each with fixed properties irrespective of their predicted occurrence. This contrasts with natural vegetation, in which many plant traits vary systematically along geographic and environmental gradients. In the JSBACH DGVM, which is part of the MPI-ESM, we allowed three traits (specific leaf area (SLA, maximum carboxylation rate at 25 °C (Vcmax25 and maximum electron transport rate at 25 °C (Jmax25 to vary within PFTs via trait–climate relationships based on a large trait database. The R2adjusted of these relationships were up to 0.83 and 0.71 for Vcmax25 and Jmax25, respectively. For SLA, more variance remained unexplained, with a maximum R2adjusted of 0.40. Compared to the default simulation, allowing trait variation within PFTs resulted in gross primary productivity differences of up to 50% in the tropics, in > 35% different dominant vegetation cover, and a closer match with a natural vegetation map. The discrepancy between default trait values and natural trait variation, combined with the substantial changes in simulated vegetation properties, together emphasize that incorporating climate-driven trait variation, calibrated on observational data and based on ecological concepts, allows more variation in vegetation responses in DGVMs and as such is likely to enable more reliable projections in unknown climates.

  9. Chemical profile and seasonal variation of phenolic acid content in bastard balm (Melittis melissophyllum L., Lamiaceae).

    Science.gov (United States)

    Skrzypczak-Pietraszek, Ewa; Pietraszek, Jacek

    2012-07-01

    Melittis melissophyllum L. is an old medicinal plant. Nowadays it is only used in the folk medicine but formerly it has been applied in the official medicine as a natural product described in French Pharmacopoeia. M. melissophyllum herbs used in our studies were collected from two localities in Poland in May and September. Methanolic plant extracts were purified by means of solid-phase extraction and then analysed by HPLC-DAD for their phenolic acid profile. Eleven compounds were identified in all plant samples and quantitatively analysed as: protocatechuic, chlorogenic, p-hydroxybenzoic, vanillic, caffeic, syringic, p-coumaric, ferulic, sinapic, o-coumaric and cinnamic acid. Plant materials contained free and bound phenolic acids. The main compounds were: p-hydroxybenzoic acid (30.21-54.16 mg/100 g dw and 37.04-56.75 mg/100 g dw, free and bound, respectively) and p-coumaric acid (40.48-80.55 mg/100 g dw and 28.09-40.85 mg/100 g dw, free and bound, respectively). The highest amounts of the investigated compounds were found in all samples collected in September, e.g. p-hydroxybenzoic acid (September 51.72-54.16 mg/100 g dw vs. May 30.21-34.07 mg/100 g dw), p-coumaric acid (September 77.14-80.55 mg/100 g dw vs. May 40.48-43.2 5mg/100 g dw). Multivariate statistical and data mining techniques, such as cluster analysis (CA) and principal component analysis (PCA), were used to characterize the sample populations according to the geographical localities, vegetation period and compound form (free or bound). To the best of our knowledge we report for the first time the results of quantitative analysis of M. melissophyllum phenolic acids and seasonal variation of their content. Plant herbs are usually collected at flowering for plant derived medical preparations. Our results show that it is not always the optimal time for the highest contents of active compounds. PMID:22513117

  10. Cellular Biology in Terms of Stochastic Nonlinear Biochemical Dynamics: Emergent Properties, Isogenetic Variations and Chemical System Inheritability

    Science.gov (United States)

    Qian, Hong

    2010-12-01

    Based on a stochastic, nonlinear, open biochemical reaction system perspective, we present an analytical theory for cellular biochemical processes. The chemical master equation (CME) approach provides a unifying mathematical framework for cellular modeling. We apply this theory to both self-regulating gene networks and phosphorylation-dephosphorylation signaling modules with feedbacks. Two types of bistability are illustrated in mesoscopic biochemical systems: one that has a macroscopic, deterministic counterpart and another that does not. In certain cases, the latter stochastic bistability is shown to be a "ghost" of the extinction phenomenon. We argue the thermal fluctuations inherent in molecular processes do not disappear in mesoscopic cell-sized nonlinear systems; rather they manifest themselves as isogenetic variations on a different time scale. Isogenetic biochemical variations in terms of the stochastic attractors can have extremely long lifetime. Transitions among discrete stochastic attractors spend most of the time in "waiting", exhibit punctuated equilibria. It can be naturally passed to "daughter cells" via a simple growth and division process. The CME system follows a set of nonequilibrium thermodynamic laws that include non-increasing free energy F( t) with external energy drive Q hk ≥0, and total entropy production rate e p =- dF/ dt+ Q hk ≥0. In the thermodynamic limit, with a system's size being infinitely large, the nonlinear bistability in the CME exhibits many of the characteristics of macroscopic equilibrium phase transition.

  11. A worldwide analysis of within-canopy variations in leaf structural, chemical and physiological traits across plant functional types.

    Science.gov (United States)

    Niinemets, Ülo; Keenan, Trevor F; Hallik, Lea

    2015-02-01

    Extensive within-canopy light gradients importantly affect the photosynthetic productivity of leaves in different canopy positions and lead to light-dependent increases in foliage photosynthetic capacity per area (AA). However, the controls on AA variations by changes in underlying traits are poorly known. We constructed an unprecedented worldwide database including 831 within-canopy gradients with standardized light estimates for 304 species belonging to major vascular plant functional types, and analyzed within-canopy variations in 12 key foliage structural, chemical and physiological traits by quantitative separation of the contributions of different traits to photosynthetic acclimation. Although the light-dependent increase in AA is surprisingly similar in different plant functional types, they differ fundamentally in the share of the controls on AA by constituent traits. Species with high rates of canopy development and leaf turnover, exhibiting highly dynamic light environments, actively change AA by nitrogen reallocation among and partitioning within leaves. By contrast, species with slow leaf turnover exhibit a passive AA acclimation response, primarily determined by the acclimation of leaf structure to growth light. This review emphasizes that different combinations of traits are responsible for within-canopy photosynthetic acclimation in different plant functional types, and solves an old enigma of the role of mass- vs area-based traits in vegetation acclimation. PMID:25318596

  12. Time Variations of the ENA Flux Observed by IBEX: Is the Outer Heliosphere Evolving?

    Science.gov (United States)

    McComas, D. J.; Bzowski, M.; Clark, G.; Crew, G. B.; Demajistre, R.; Funsten, H. O.; Fuselier, S. A.; Gruntman, M.; Janzen, P.; Livadiotis, G.; Moebius, E.; Reisenfeld, D. B.; Roelof, E. C.; Schwadron, N. A.

    2009-12-01

    The Interstellar Boundary Explorer (IBEX) mission has just provided the first global observations of the heliosphere’s interstellar interaction [McComas et al., 2009 and other papers in the IBEX special issue of Science]. IBEX all-sky maps and energy spectra provide detailed information about this interaction. Because of the way IBEX collects its observations, each swath of the sky is revisited every six months, with the winter viewing, when IBEX’s orbit is largely sunward of the Earth, providing significantly cleaner measurements than the summer season, when IBEX’s orbit rotates through the Earth’s magnetosheath and magnetotail. Very limited initial overlapping data showed that the observed structure was largely stable over the first six months of observations, however, it also suggested the tantalizing possibility that there could be some temporal evolution. By the time of the Fall AGU meeting, much of the sky will be imaged a second time. This study will provide a comparison of these sets of observations, especially at higher energies where the statistics are better, and directly address the question of if the outer heliosphere is evolving over timescales on the order of half a year. Reference McComas, D.J., F. Allegrini, P. Bochsler, M. Bzowski, E.R. Christian, G.B. Crew, R. DeMajistre, H. Fahr, H. Fichtner, P.C. Frisch, H.O. Funsten, S. A. Fuselier, G. Gloeckler, M. Gruntman, J. Heerikhuisen, V. Izmodenov, P. Janzen, P. Knappenberger, S. Krimigis, H. Kucharek, M. Lee, G. Livadiotis, S. Livi, R.J. MacDowall, D. Mitchell, E. Möbius, T. Moore, N.V. Pogorelov, D. Reisenfeld, E. Roelof, L. Saul, N.A. Schwadron, P.W. Valek, R. Vanderspek, P. Wurz, G.P. Zank, First Global Observations of the Interstellar Interaction from the Interstellar Boundary Explorer, submitted to Science, 2009.

  13. Meridional variation in tropospheric methane on Titan observed with AO spectroscopy at Keck and VLT

    OpenAIRE

    Ádámkovics, Máté; Mitchell, Jonathan L.; Hayes, Alexander G.; Rojo, Patricio M.; Corlies, Paul; Barnes, Jason W.; Ivanov, Valentin D.; Brown, Robert H.; Baines, Kevin H.; Buratti, Bonnie J.; Clark, Roger N.; Nicholson, Philip D.; Sotin, Christophe

    2015-01-01

    The spatial distribution of the tropospheric methane on Titan was measured using near-infrared spectroscopy. Ground-based observations at 1.5$\\mu{\\rm m}$ (H-band) were performed during the same night using instruments with adaptive optics at both the W. M. Keck Observatory and at the Paranal Observatory on 17 July 2014 UT. The integral field observations with SINFONI on the VLT covered the entire H-band at moderate resolving power, $R=\\lambda/\\Delta\\lambda\\approx1,500$, while the Keck observa...

  14. Time Variation Observations of Mid-Infrared Spectra of Mira Variables in NEP and LMC

    Science.gov (United States)

    Onaka, Takashi; Miyata, Takashi; Okada, Yoko; Sakon, Itsuki; Tanabe, Toshihiko; Yamamura, Issei

    2004-09-01

    We propose to derive the optical properties of their circumstellar dust grains and dust formation process based on variability observations of mid-infrared (MIR) spectra of oxygen-rich Mira variables with the IRS SL and LL modules. Mass-loss of stars in the asymptotic-giant branch is an important process for the evolution of matter in the Galaxy. However, there are still large uncertainties in the optical properties of silicate grains and the dust formation process in their circumstellar envelopes. Based on variability observations with the ISO of MIR spectra of a Mira variable we were able to derive the dust optical properties and the inner dust shell temperature independently, which have clearly demonstrated the effectiveness of variability observations of MIR spectra. However, they also indicate that the variability and dust properties in Mira variables have diversity and it is quite important to apply the same method to other targets and extend the investigation. We selected 3 target stars in the north ecliptic polar (NEP) region and 2 in the Large Magellanic Cloud (LMC). Both regions are located in the constant viewing zones and all the target stars can be observed for more than 11 months in a year. We propose to make observations in the intervals of 1/5 of the period over a variability cycle. Three targets in the NEP have periods less than 300 days and they can be observed over a variability cycle in Cycle-1. Two target stars in the LMC have periods longer than 500 days and we request multi-cycle observations to cover a variability cycle of the LMC targets. We allow +/-15 days for the NEP stars and +/-30 days for the LMC stars for each observation epoch and thus the timing constraint is not severe. The IRS on board the SST provides a unique opportunity to carry out this study, which enables us to investigate the diversity of properties and formation process of silicate grains in Mira variables and extend our understanding to those in the nearby galaxy LMC.

  15. Solar wind dependence of the electron flux variation at geostationary orbit observed by ETS-V

    OpenAIRE

    Yokoyama,N./Goka,T./Matsumoto,H./Koga,K./Koshiishi, H./Kimoto, Y.

    2001-01-01

    In this study we have examined the relationship between the energetic electron flux at geostationary orbit and the solar wind speed. We have compared the electron flux ( >0.4MeV) observed by the Engineering Test Satellite V (ETS-V) with solar wind speed measurements in the OMNI data set obtained from the National Space Science Data Center (NSSDC). The tendency has been observed for the logarithm of the electron flux to be proportional to the solar wind speed at solar minimum, but scattered at...

  16. Ionospheric longitudinal variations at midlatitudes:Incoherent scatter radar observation at Millstone Hill

    Institute of Scientific and Technical Information of China (English)

    ZHANG ShunRong; COSTER Anthea; HOLT John; FOSTER John; ERICKSON Phil

    2012-01-01

    Incoherent scatter radar (ISR) extra-wide coverage experiments during the period of 1978-2011 at Millstone Hill are used to investigate longitudinal differences in electron density.This work is motivated by a recent finding of the US east-west coast difference in TEC suggesting a combined effect of changing geomagnetic declination and zonal winds.The current study provides strong supporting evidence of the longitudinal change and the plausible mechanism by examining the climatology of electron density Ne on both east and west sides of the radar with a longitude separation of up to 40° for different heights within 300-450 km.Main findings include:1) The east-west difference can be up to 60% and varies over the course of the day,being positive (East side Ne > West side Ne) in the late evening,and negative (West side Ne > East side Ne) in the pre-noon.2) The east-west difference exists throughout the year.The positive (relative) difference is most pronounced in winter; the negative (relative) difference is most pronounced in early spring and later summer.3) The east-west difference tends to enhance toward decreasing solar activity,however,with some seasonal dependence; the enhancements in the positive and negative differences do not take place simultaneously.4) Both times of largest positive and largest negative east-west differences in Ne are earlier in summer and later in winter.The two times differ by 12-13 h,which remains constant throughout the year.5) Variations at different heights from 300-450 km are similar.Zonal wind climatology above Millstone Hill is found to be perfectly consistent with what is expected based on the electron density difference between the east and west sides of the site.The magnetic declination-zonal wind mechanism is true for other longitude sectors as well,and may be used to understand longitudinal variations elsewhere.It may also be used to derive thermospheric zonal winds.

  17. Temporal Variations in Physico-Chemical and Microbiological Characteristics of Mvudi River, South Africa

    Directory of Open Access Journals (Sweden)

    Joshua N. Edokpayi

    2015-04-01

    Full Text Available Surface water has been a source of domestic water due to shortage of potable water in most rural areas. This study was carried out to evaluate the level of contamination of Mvudi River in South Africa by measuring turbidity, electrical conductivity (EC, pH, concentrations of nitrate, fluoride, chloride, and sulphate. E. coli and Enterococci were analysed using membrane filtration technique. Average pH, EC and Turbidity values were in the range of 7.2–7.7, 10.5–16.1 mS/m and 1.3–437.5 NTU, respectively. The mean concentrations of fluoride, chloride, nitrate and sulphate for both the wet and the dry seasons were 0.11 mg/L and 0.27 mg/L, 9.35 mg/L and 14.82 mg/L, 3.25 mg/L and 6.87 mg/L, 3.24 mg/L and 0.70 mg/L, respectively. E. coli and Enterococci counts for both the wet and the dry seasons were 4.81 × 103 (log = 3.68 and 5.22 × 103 (log = 3.72, 3.4 × 103 (log = 3.53 and 1.22 × 103 (log = 3.09, per 100 mL of water, respectively. The count of E. coli for both seasons did not vary significantly (p > 0.05 but Enterococci count varied significantly (p < 0.001. All the physico-chemical parameters obtained were within the recommended guidelines of the Department of Water Affairs and Forestry of South Africa and the World Health Organization for domestic and recreational water use for both seasons except turbidity and nitrates. The microbiological parameters exceeded the established guidelines. Mvudi River is contaminated with faecal organisms and should not be used for domestic purposes without proper treatment so as to mitigate the threat it poses to public health.

  18. A STUDY OF SEASONAL VARIATION OBSERVED IN OCCURRENCE OF IMMINENT ECLAMPSIA AND ECLAMPSIA AT TERTIARY CARE HOSPITAL

    Directory of Open Access Journals (Sweden)

    Ashutosh

    2016-02-01

    Full Text Available BACKGROUND Eclampsia is an occurrence of seizures in women with pre-eclampsia. It is a leading cause of maternal mortality and morbidity in India. Their etiology is poorly understood even today. Seasonal variation is considered as one of the cause. AIMS AND OBJECTIVES To see the frequency of occurrence of imminent eclampsia and eclampsia during rainy (June to August and winter (October to December season. MATERIALS AND METHOD This is a descriptive, retrospective, observational and analytical study on seasonal variations in admission of imminent eclampsia and eclampsia patients in Department of Obstetrics and Gynaecology in KIMS, Karad, from 2012 to 2014. RESULT Among 9122 total number of admissions in Department of Obstetrics and Gynaecology 7678 got delivered in our institute. In which 4150 deliveries occurred in rainy season in which imminent eclampsia were 55 (1.3%, eclampsia cases were 42 (1.01%. While 3528 cases delivered in winter in which imminent eclampsia were 28 (0.7% and eclampsia were 24 (0.68%. The study showed frequency of imminent eclampsia and eclampsia being more common in rainy season than that of winter season. CONCLUSION In our study, we observed the seasonal variation in occurrence of imminent eclampsia and eclampsia. Number of cases of both imminent eclampsia and eclampsia was more common in rainy season. Regular health checkup, availability of health facilities and prompt referral to tertiary hospital can decrease mortality and morbidity of patient.

  19. Singular vector based targeted observations of chemical constituents: description and first application of the EURAD-IM-SVA

    Science.gov (United States)

    Goris, N.; Elbern, H.

    2015-08-01

    Measurements of the large dimensional chemical state of the atmosphere provide only sparse snapshots of the state of the system due to their typically insufficient temporal and spatial density. In order to optimize the measurement configurations despite those limitations, the present work describes the identification of sensitive states of the chemical system as optimal target areas for adaptive observations. For this purpose, the technique of singular vector analysis (SVA), which has been proved effective for targeted observations in numerical weather predication, is implemented into the chemical transport model EURAD-IM (EURopean Air pollution and Dispersion - Inverse Model) yielding the EURAD-IM-SVA. Besides initial values, emissions are investigated as critical simulation controlling targeting variables. For both variants, singular vectors are applied to determine the optimal placement for observations and moreover to quantify which chemical compounds have to be observed with preference. Based on measurements of the airship based ZEPTER-2 campaign, the EURAD-IM-SVA has been evaluated by conducting a comprehensive set of model runs involving different initial states and simulation lengths. Since the considered cases are restricted in terms of considered chemical compounds and selected areas, they allow for a retracing of the results and a confirmation of their correctness. Our analysis shows that the optimal placement for observations of chemical species is not entirely determined by mere transport and mixing processes. Rather, a combination of initial chemical concentrations, chemical conversions, and meteorological processes determine the influence of chemical compounds and regions. We furthermore demonstrate that the optimal placement of observations of emission strengths is highly dependent on the location of emission sources and that the benefit of including emissions as target variables outperforms the value of initial value optimisation with growing

  20. Meridional variation in tropospheric methane on Titan observed with AO spectroscopy at Keck and VLT

    CERN Document Server

    Ádámkovics, Máté; Hayes, Alexander G; Rojo, Patricio M; Corlies, Paul; Barnes, Jason W; Ivanov, Valentin D; Brown, Robert H; Baines, Kevin H; Buratti, Bonnie J; Clark, Roger N; Nicholson, Philip D; Sotin, Christophe

    2015-01-01

    The spatial distribution of the tropospheric methane on Titan was measured using near-infrared spectroscopy. Ground-based observations at 1.5$\\mu{\\rm m}$ (H-band) were performed during the same night using instruments with adaptive optics at both the W. M. Keck Observatory and at the Paranal Observatory on 17 July 2014 UT. The integral field observations with SINFONI on the VLT covered the entire H-band at moderate resolving power, $R=\\lambda/\\Delta\\lambda\\approx1,500$, while the Keck observations were performed with NIRSPAO near 1.55254$\\mu{\\rm m}$ at higher resolution, $R\\approx25,000$. The moderate resolution observations are used for flux calibration and for the determination of model parameters that can be degenerate in the interpretation of high resolution spectra. Line-by-line calculations of CH$_4$ and CH$_3$D correlated $k$ distributions from the HITRAN 2012 database were used, which incorporate revised line assignments near 1.5$\\mu{\\rm m}$. We fit the surface albedo and aerosol distributions in the ...

  1. Galileo SSI and Cassini ISS Observations of Io's Pele Hotspot: Temperatures, Areas, and Variation with Time

    Science.gov (United States)

    Radebaugh, J.; McEwen, A. S.; Milazzo, M.; Davies, A. G.; Keszthelyi, L. P.; Geissler, P.

    2002-01-01

    Temperatures of Io's Pele hotspot were found using dual-filter observations from Galileo and Cassini. Temperatures average 1375 K, but vary widely over tens of minutes. Dropoff in emission with rotation consistent with lava fountaining at a lava lake. Additional information is contained in the original extended abstract.

  2. Azimuthal Variations in Polarimetric Microwave Measurements Observed over Dome C, Antarctica

    Science.gov (United States)

    WindSat is the first spaceborne fully polarimetric radiometer. It observes all four components Tv (vertically polarized), Th (horizontally), U (difference between polarizations at +45° and -45°) and V (difference right hand minus left hand circular polarized) of the Stokes vector. While originally d...

  3. Observation of muon intensity variations by season with the MINOS far detector

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, P.; /Fermilab; Andreopoulos, C.; /Rutherford; Arms, K.E.; /Minnesota U.; Armstrong, R.; /Indiana U.; Auty, D.J.; /Sussex U.; Ayres, D.S.; /Argonne; Backhouse, C.; /Oxford U.; Barnett, J.; /Oxford U.; Barr, G.; /Oxford U.; Barrett, W.L.; /Western Washington U.; Becker, B.R.; /Minnesota U. /Brookhaven

    2009-09-01

    The temperature of the upper atmosphere affects the height of primary cosmic ray interactions and the production of high-energy cosmic ray muons which can be detected deep underground. The MINOS far detector at Soudan MN, USA, has collected over 67 million cosmic ray induced muons. The underground muon rate measured over a period of five years exhibits a 4% peak-to-peak seasonal variation which is highly correlated with the temperature in the upper atmosphere. The coefficient, {alpha}{sub T}, relating changes in the muon rate to changes in atmospheric temperature was found to be: {alpha}{sub T} = 0.874 {+-} 0.009 (stat.) {+-} 0.010$ (syst.). Pions and kaons in the primary hadronic interactions of cosmic rays in the atmosphere contribute differently to {alpha}{sub T} due to the different masses and lifetimes. This allows the measured value of {alpha}{sub T} to be interpreted as a measurement of the K{pi} ratio for E{sub p}/unit[7](TeV) of $0.13 {+-} 0.08, consistent with the expectation from collider experiments.

  4. Observation of muon intensity variations by season with the MINOS far detector

    CERN Document Server

    ,

    2009-01-01

    The temperature of the upper atmosphere affects the height of primary cosmic ray interactions and the production of high-energy cosmic ray muons which can be detected deep underground. The MINOS far detector at Soudan MN, USA, has collected over 67 million cosmic ray induced muons. The underground muon rate measured over a period of five years exhibits a 4% peak-to-peak seasonal variation which is highly correlated with the temperature in the upper atmosphere. The coefficient, $\\alpha_T$, relating changes in the muon rate to changes in atmospheric temperature was found to be: $\\alpha_T = 0.874 \\pm 0.009$ (stat.) $\\pm 0.010$ (syst.). Pions and kaons in the primary hadronic interactions of cosmic rays in the atmosphere contribute differently to $\\alpha_T$ due to the different masses and lifetimes. This allows the measured value of $\\alpha_T$ to be interpreted as a measurement of the K/$\\pi$ ratio for $E_{p}\\gtrsim$\\unit[7]{TeV} of $0.13 \\pm 0.08$, consistent with the expectation from collider experiments.

  5. Humidity variations across the edge of trade wind cumuli: Observations and dynamical implications

    Science.gov (United States)

    Wang, Yonggang; Geerts, Bart

    2010-07-01

    Aircraft data are used to analyze the composite horizontal structure of shallow tropical maritime cumulus clouds across the cloud edge into the ambient clear air. The emphasis is on humidity variations, and their implications for cumulus dynamics. The Lyman-α humidity probe has the required fast response and is unaffected by wetting in-cloud. On average the water vapor mixing ratio increases gradually from the clear air towards the cloud edge, and air is often sub-saturated in the outer fringe of the cloud, implying that droplets are evaporating. Similarly, conserved variables such as the total water concentration and the wet equivalent potential temperature gradually transition in the "margin" of cumulus clouds. The gradual change of water vapor mixing ratio and conserved variables across the cloud edge highlights the significance of lateral entrainment and detrainment, and it reveals a characteristic penetration depth of mixing eddies of 10 to 15% of the cloud diameter, or about 50 m. An ˜ 100 m wide region just outside the cloud is generally characterized by negatively buoyant, sinking air. The excess water vapor in this region, also documented in several recent studies, confirms that the negative buoyancy is caused by evaporative cooling in the cloud margin. Although rather weak, this cooling appears strong enough to evoke a dynamical response, even in the relative small trade wind cumuli.

  6. Subnasal morphological variation in fossil hominids: a reassessment based on new observations and recent developmental findings.

    Science.gov (United States)

    McCollum, M A

    2000-06-01

    Quantitative and qualitative assessments of subnasal morphology in fossil hominids yield distinct patterns which have been used both to sort robust from nonrobust australopithecine taxa and to distinguish individual species. Recently, new developmental models have been applied to hominoid subnasal morphological variation. These studies require that certain features of the fossil hominid subnasal region, in particular the topography of the nasal cavity entrance and details of vomeral morphology, be reevaluated. This study does so for the robust and nonrobust australopithecines, early Homo (H. habilis/H. rudolfensis), and African H. erectus. Results reaffirm an overall similarity of the nonrobust Australopithecus subnasal morphological pattern with that of the chimpanzee. They further indicate that a vomeral insertion above the nasal surface of the premaxilla should be added to the list of traits characteristic of the robust australopithecine subnasal morphological pattern. Finally, reassessment of subnasal morphology in the early Homo and H. erectus samples from Africa suggest that these two taxa share a similar subnasal morphological pattern. This pattern consists of a smooth nasal cavity entrance, a horizontal nasal sill whose anterior edge is demarcated by a strong nasal crest, and a well-developed horizontal spine at the posterior edge of the nasal sill. Although none of the African fossil Homo specimens preserve a vomer, indirect evidence suggests that it would have inserted above the nasal sill. PMID:10813707

  7. Measurements of nitric oxide and total reactive nitrogen in the Antarctic stratosphere: Observations and chemical implications

    International Nuclear Information System (INIS)

    Measurements of NO and the sum of reactive nitrogen species, NOy, were made as part of the Airborne Antarctic Ozone Experiment (AAOE) on flights of the NASA ER-2 aircraft over the Antarctic continent. Reactive nitrogen species include NO,NO2, NO3, N2O5, HNO3, and ClONO2. The technique utilized the conversion of NOy components to NO on a gold catalyst and the subsequent detection of NO by the chemiluminescent reaction of NO with O3. NO was measured on two of the flights by removing the catalyst from the sample line. The boundary of a chemically perturbed region (CPR) above the continent occurred on average near 66 degree S as indicated by a sharp increase in the level of ClO. Outside or equatorward of the CPR, NOy mixing ratios ranged between 6 and 12 parts per billion by volume (ppbv), with values increasing with latitude. At the edge of the CPR, large latitude gradients of NOyand NO were found with values decreasing poleward. Total NOy levels dropped to 4 ppbv or less within 5 degree poleward of the boundary. NO values were 0.1-0.2 ppbv outside and below the detection limit of 0.03 ppbv inside the CPR. The levels of NO and NOy observed preclude a chemical loss of ozone due to reaction with NO

  8. Variation of chemical composition of high strength low alloy steels with different groove sizes in multi-pass conventional and pulsed current gas metal arc weld depositions

    Directory of Open Access Journals (Sweden)

    K. Devakumaran

    2015-06-01

    Full Text Available 25 mm thick micro-alloyed HSLA steel plate is welded by multi-pass GMAW and P-GMAW processes using conventional V-groove and suitably designed narrow gap with 20 mm (NG-20 and 13 mm (NG-13 groove openings. The variation of weld metal chemistry in the multi pass GMA and P-GMA weld depositions are studied by spark emission spectroscopy. It is observed that the narrow groove GMA weld joint shows significant variation of weld metal chemistry compared to the conventional V-groove GMA weld joint since the dilution of base metal extends from the deposit adjacent to groove wall to weld center through dissolution by fusion and solid state diffusion. Further, it is noticed that a high rate of metal deposition along with high velocity of droplet transfer in P-GMAW process enhances the dilution of weld deposit and accordingly varies the chemical composition in multi-pass P-GMA weld deposit. Lower angle of attack to the groove wall surface along with low heat input in NG-13 weld groove minimizes the effect of dissolution by fusion and solid state diffusion from the deposit adjacent to groove wall to weld center. This results in more uniform properties of NG-13 P-GMA weld in comparison to those of NG-20 and CG welds.

  9. Co-variation of Temperature and Precipitation in CMIP5 Models and Satellite Observations

    Science.gov (United States)

    Liu, Chunlei; Allan, Richard P.; Huffman, George J.

    2013-01-01

    Current variability of precipitation (P) and its response to surface temperature (T) are analysed using coupled (CMIP5) and atmosphere-only (AMIP5) climate model simulations and compared with observational estimates.There is striking agreement between Global Precipitation Climatology Project (GPCP) observed and AMIP5)simulated P anomalies over land both globally and in the tropics suggesting that prescribed sea surface temperature and realistic radiative forcings are sufficient for simulating the interannual variability in continental P. Differences between the observed and simulated P variability over the ocean, originate primarily from the wet tropical regions, in particular the western Pacific, but are reduced slightly after 1995. All datasets show positive responses of P to T globally of around 2 % K for simulations and 3-4 % K in GPCP observations but model responses over the tropical oceans are around 3 times smaller than GPCP over the period 1988-2005. The observed anticorrelation between land and ocean P, linked with El Nio Southern Oscillation, is captured by the simulations. All data sets over the tropical ocean show a tendency for wet regions to become wetter and dry regions drier with warming. Over the wet region (greater than or equal to 75 precipitation percentile), the precipitation response is 13-15%K for GPCP and 5%K for models while trends in P are 2.4% decade for GPCP, 0.6% decade for CMIP5 and 0.9decade for AMIP5 suggesting that models are underestimating the precipitation responses or a deficiency exists in the satellite datasets.

  10. Meridional variation in tropospheric methane on Titan observed with AO spectroscopy at Keck and VLT

    Science.gov (United States)

    Ádámkovics, Máté; Mitchell, Jonathan L.; Hayes, Alexander G.; Rojo, Patricio M.; Corlies, Paul; Barnes, Jason W.; Ivanov, Valentin D.; Brown, Robert H.; Baines, Kevin H.; Buratti, Bonnie J.; Clark, Roger N.; Nicholson, Philip D.; Sotin, Christophe

    2016-05-01

    The spatial distribution of the tropospheric methane on Titan was measured using near-infrared spectroscopy. Ground-based observations at 1.5 μm (H-band) were performed during the same night using instruments with adaptive optics at both the W.M. Keck Observatory and at the Paranal Observatory on 17 July 2014 UT. The integral field observations with SINFONI on the VLT covered the entire H-band at moderate resolving power, R = λ / Δλ ≈ 1500 , while the Keck observations were performed with NIRSPAO near 1.5525 μm at higher resolution, R ≈ 25, 000 . The moderate resolution observations are used for flux calibration and for the determination of model parameters that can be degenerate in the interpretation of high resolution spectra. Line-by-line calculations of CH4 and CH3D correlated k distributions from the HITRAN 2012 database were used, which incorporate revised line assignments near 1.5 μm . We fit the surface albedo and aerosol distributions in the VLT SINFONI observations that cover the entire H-band window and used these quantities to constrain the models of the high-resolution Keck NIRSPAO spectra when retrieving the methane abundances. Cassini VIMS images of the polar regions, acquired on 20 July 2014 UT, are used to validate the assumption that the opacity of tropospheric aerosol is relatively uniform below 10 km. We retrieved methane abundances at latitudes between 42°S and 80°N. The tropospheric methane in the Southern mid-latitudes was enhanced by a factor of ∼10-40% over the nominal profile that was measured using the GCMS on Huygens. The northern hemisphere had ∼90% of the nominal methane abundance up to polar latitudes (80°N). These measurements suggest that a source of saturated polar air is equilibrating with dryer conditions at lower latitudes.

  11. Changes In Some Physiological And Chemical Parameters Of Ostrich In Response To The Seasonal And Diurnal Temperature Variations

    International Nuclear Information System (INIS)

    The present study was carried out to evaluate the effect of temperature variation during summer and winter seasons and diurnal effect on ostrich performance and changes in some physiological and blood chemical parameters. Twelve immature ostrich birds (7 months old) were exposed to daily natural ambient temperatures during the summer and winter. The birds were fed a grower ration ad libitum (19 % protein and 2450 K cal ME/kg) and the daily feed consumption (g/ bird/day) and water consumption (ml/bird/day) were measured for a representative 7 days during each season. Cloacal temperatures was measured and blood samples were collected twice; one in the morning at 7:00 am and the other in the afternoon at 15.00 pm during a representative 7 hot days of June (40±2 degree C) (summer) and the 7 cold days of January (18±2 degree C) (winter). Red blood cells count (RBC) and total white blood cells count (WBC), hemoglobin (Hb) and packed cell volume (PCV) were determined. Mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular hemoglobin concentrations (MCHC) were calculated. In serum, levels of total protein (TP), albumin (A) and globulin (G), alanine transaminase (ALT), aspartate transaminase (AST), glucose, triglycerides, cholesterol, triiodothyronine (T3) and cortisol were estimated. Results indicated that feed consumption unlike water consumption was significantly increased during winter than in summer season. Moreover, body temperature was increased significantly during the summer season as compared with the winter season and was significantly elevated at the afternoon than at the morning. Blood picture showed that hemoglobin (Hb), packed cell volume (PCV), red blood cells count (RBC) and total white blood cells count (WBC) were significantly decreased in the summer than in winter at the two diurnal periods. Also, both mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) were significantly increased in summer than winter

  12. On transient electric fields observed in chemical release experiments by rockets

    International Nuclear Information System (INIS)

    As a follow-up to the successful chemical release experiment Trigger in 1977, the Trigger Optimized Repetition rocket was launched from Esrange on October 24, 1984. As in the Trigger experiment, a large-amplitude electric field pulse of 200 mV/m was detected shortly after the explosion.The central part of the pulse was found to be clearly correlated with an intense layer of swept up ambient particles behind a propagating shock front. The field was directed toward the center of the expanding ionized cloud, which is indicative of a polarization electric field source. Expressions for this radial polarization field and the much weaker azimuthal-induced electric field are derived from a simple cylindrical model for the field and the expanding neutral cloud. Time profiles of the radial electric field are shown to be in good agreement with observations

  13. On transient electric fields observed in chemical release experiments by rockets

    International Nuclear Information System (INIS)

    As a follow-up to the successful chemical release experiment Trigger in 1977, the TOR (Trigger Optimized Repetition) rocket was launched from Esrange on Oct. 24, 1984. Like in the Trigger experiment a large amplitude electric field pulse of 200 mV/m was detected shortly after the explosion. The central part of the pulse was found to be clearly correlated with an intense layer of swept up ambient particles behind a propagating shock-front. The field was directed towards the centre of the expanding ionized cloud, which is indicative of a polarisation electric field source. Expressions for this radial polarisation field and the much weaker azimuthal induced electric field are derived from a simple cylindrical model for the field and the expanding neutral cloud. Time profiles of the radial electric field are shown to be in good agreement with observations. (authors)

  14. On transient electric fields observed in chemical release experiments by rockets

    Science.gov (United States)

    Marklund, G.; Brenning, N.; Holmgren, G.; Haerendel, G.

    1987-05-01

    As a follow-up to the successful chemical release experiment Trigger in 1977, the Trigger Optimized Repetition rocket was launched on October 24, 1984. As in the Trigger experiment, a large-amplitude electric field pulse of 200 mV/m was detected shortly after the explosion. The central part of the pulse was found to be clearly correlated with an intense layer of swept up ambient particles behind a propagating shock front. The field was directed toward the center of the expanding ionized cloud, which is indicative of a polarization electric field source. Expressions for this radial polarization field and the much weaker azimuthal-induced electric field are derived from a simple cylindrical model for the field and the expanding neutral cloud. Time profiles of the radial electric field are shown to be in good agreement with observations.

  15. The enhanced greenhouse signal versus natural variations in observed climate time series: a statistical approach

    Energy Technology Data Exchange (ETDEWEB)

    Schoenwiese, C.D. [J.W. Goethe Univ., Frankfurt (Germany). Inst. for Meteorology and Geophysics

    1995-12-31

    It is a well-known fact that human activities lead to an atmospheric concentration increase of some IR-active trace gases (greenhouse gases GHG) and that this influence enhances the `greenhouse effect`. However, there are major quantitative and regional uncertainties in the related climate model projections and the observational data reflect the whole complex of both anthropogenic and natural forcing of the climate system. This contribution aims at the separation of the anthropogenic enhanced greenhouse signal in observed global surface air temperature data versus other forcing using statistical methods such as multiple (multiforced) regressions and neural networks. The competitive natural forcing considered are volcanic and solar activity, in addition the ENSO (El Nino/Southern Oscillation) mechanism. This analysis will be extended also to the NAO (North Atlantic Oscillation) and anthropogenic sulfate formation in the troposphere

  16. A climatic variation observed in permafrost temperature at Kangiqsualujjuaq in northern Quebec

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Permafrost temperatures from the surface down to about 9 m from 3 bore holes distributed around Kangiqsualujjuaq village on the coast of Hudson Strait were recorded and analyzed for the period 1989-1998. The results indicate that the permafrost is getting warm along the southern shore of Hudson Strait from 1993 to 1998 though it became cooling for the past 40 a or more. The observed trend in the order of 0. 098℃/a at the 9 m depth is consistent with the long-term regional warming observed in air temperatures. It also coincides with that all the global circulation models predict an enhanced warming in polar regions associated with the increase in concentration of greenhouse gases in the atmosphere.

  17. Modeling of geomagnetic field secular variations observed in the Balkan area for purposes of regional topographic mapping

    Science.gov (United States)

    Metodiev, Metodi; Trifonova, Petya; Buchvarov, Ivan

    2014-05-01

    The most significant of the Earth's magnetic field elements is the geomagnetic declination, which is widely used in geodesy, cartography and their associated navigational systems. The geomagnetic declination is incorporated in the naval navigation maps and is used in the navigation process. It is also a very important factor for aviation where declination data have major importance for every airport (civil or military). As the geomagnetic field changes with time but maps of the geomagnetic declination are not published annually and are reduced to an epoch in the past, it is necessary to define two additional parameters in the maps, needed to determine the value of the geomagnetic declination for a particular moment in the future: 1) estimated value of the annual declination variation and 2) a table with the average diurnal variation of the declination for a given month and hour. The goal of our research is to analyze the annual mean values of geomagnetic declination on the territory of the Balkan Peninsula for obtaining of a best fitting model of that parameter which can be used for prediction of the declination value for the next 10 years. The same study was performed in 1990 for the purposes of Bulgarian declination map's preparation. As a result, a linear model of the declination annual variation was obtained for the neighboring observatories and repeat stations data, and a map of the obtained values for the Bulgarian territory was drawn. We use the latest version of the GFZ Reference Internal Magnetic Model (GRIMM-3.0) to compare the magnetic field evolution predicted by that model between 2001 and 2010 to the data collected in five independent geomagnetic observatories in the Balkan region (PAG, SUA, PEG, IZN, GCK) over the same time interval. We conclude that the geomagnetic core field secular variation in this area is well described by the global model. The observed small-scale differences might indicate induced lithospheric anomalies but it is still an open

  18. Atmospheric multidecadal variations in the North Atlantic realm: proxy data, observations, and atmospheric circulation model studies

    OpenAIRE

    Grosfeld, K.; G. Lohmann; N. Rimbu; Fraedrich, K.; F. Lunkeit

    2007-01-01

    We investigate the spatial and temporal characteristics of multidecadal climate variability in the North Atlantic realm, using observational data, proxy data and model results. The dominant pattern of multidecadal variability of SST depicts a monopolar structure in the North Atlantic during the instrumental period with cold (warm) phases during 1900–1925 and 1970–1990 (1870–1890 and 1940–1960). Two atmospheric general circulation models of different com...

  19. Paleointensity variation across the Matuyama-Brunhes polarity transition: Observations from lavas at Punaruu Valley, Tahiti

    Science.gov (United States)

    Mochizuki, Nobutatsu; Oda, Hirokuni; Ishizuka, Osamu; Yamazaki, Toshitsugu; Tsunakawa, Hideo

    2011-06-01

    We have conducted a paleointensity study of the Matuyama-Brunhes (M-B) polarity transition recorded in 34 successive lava flows of Punaruu Valley on Tahiti. A reversed polarity is obtained from the lower part of the record, major directional changes are derived from the middle part of the record, and a normal polarity is recorded in the upper part of the record. These paleomagnetic directions and five 40Ar/39Ar ages yielding a weighted mean of 771 ± 8 (1σ) ka indicate that 30 lava flows recorded the geomagnetic field across the M-B transition. The 215 specimens from 32 flows were subjected to the double-heating technique of the Shaw method combined with low-temperature demagnetization (LTD-DHT Shaw method), yielding 73 successful results from 18 flows. For the reversed polarity period just prior to the major directional changes, paleointensity shows an oscillation-like variation between 3 and 38 μT corresponding to virtual dipole moments (VDMs) between 0.9 × 1022 and 9.6 × 1022 Am2. For the major directional changes, a weak paleointensity of 5 μT is obtained, which gives a VDM of 1.0 × 1022 Am2. For the normal polarity period, paleointensities are 14-21 μT, giving VDMs of 3.5-5.2 × 1022 Am2. For the reversed polarity period just prior to the major directional changes, a linear relationship with a correlation coefficient of 0.96 is recognized on the diagram of VDM versus virtual geomagnetic pole latitude. This linear relationship may be a precursory feature of the geodynamo at the onset of the M-B transition.

  20. Observer variation in FDG PET-CT for staging of non-small-cell lung carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Hofman, Michael S. [St Thomas' Hospital, PET Imaging Centre, London (United Kingdom)]|[Southern Health, Nuclear Medicine, Melbourne (Australia); Smeeton, Nigel C. [King' s College London, Division of Health and Social Care Research, London (United Kingdom); Rankin, Sheila C.; Nunan, Tom; O' Doherty, Michael J. [St Thomas' Hospital, PET Imaging Centre, London (United Kingdom)

    2009-02-15

    Error and variation in reporting remains one of the weakest features of clinical imaging despite enormous technological advances in nuclear medicine and radiology. The aim of this study was to evaluate agreement amongst experienced readers in staging non-small-cell lung cancer (NSCLC) with PET-CT. A series of {sup 18}F-FDG PET-CT scans from 100 consecutive patients were reviewed independently by three experienced readers, with two readers reviewing each scan series a second time. Individual mediastinal lymph node stations were assessed as benign/inflammatory, equivocal or malignant, and AJCC N and M stage were also assigned. Kappa ({kappa}) was used to compare ratings from two categories and weighted kappa ({kappa}{sub w}) for three or more categories, and kappa values were interpreted according to the Landis-Koch benchmarks. Both intra- and interobserver agreement for N and M staging were high. For M staging there was almost perfect intra- and interobserver agreement ({kappa} = 0.90-0.93). For N staging, agreement was either almost perfect or substantial (intraobserver {kappa}{sub w} = 0.79, 0.91; interobserver {kappa}{sub w} = 0.75-0.81). Importantly, there was almost perfect agreement for N0/1 vs N2/3 disease ({kappa} = 0.80-0.97). Agreement for inferior and superior mediastinal nodes (stations 1, 2, 3, 7, 8, 9) was either almost perfect or substantial ({kappa}{sub w} = 0.71-0.88), but lower for hilar nodes (10; {kappa}{sub w} = 0.56-0.71). Interreporter variability was greatest for aortopulmonary nodes (5, 6; {kappa}{sub w} = 0.48-0.55). Amongst experienced reporters in a single centre, there was a very high level of agreement for both mediastinal nodal stage and detection of distant metastases with PET-CT. This supports the use of PET-CT as a robust imaging modality for staging NSCLC. (orig.)

  1. Signal and noise in Gravity Recovery and Climate Experiment (GRACE) observed surface mass variations

    Science.gov (United States)

    Schrama, Ernst J. O.; Wouters, Bert; LavalléE, David A.

    2007-08-01

    The Gravity Recovery and Climate Experiment (GRACE) product used for this study consists of 43 monthly potential coefficient sets released by the GRACE science team which are used to generate surface mass thickness grids expressed as equivalent water heights (EQWHs). We optimized both the smoothing radius and the level of approximation by empirical orthogonal functions (EOFs) and found that 6.25° and three modes are able to describe more than 73.5% of the variance. The EQWHs obtained by the EOF method describe all known variations in the continental hydrology, present-day ice sheet melting, and global isostatic adjustment. To assess the quality of the estimated grids, we constructed degree error spectra of EQWHs. We conclude that a significant part of the errors in GRACE can be explained by a scaling factor of 0.85 relative to degree error estimates provided by the GGM02C gravity model but that the present-day errors in the GRACE data are a factor 2 to 5 larger than forecasted by tide model differences and atmospheric pressure differences. Comparison to a network of 59 International GNSS Service (IGS) stations confined the filter parameter settings to three EOF modes and 5° or 6.25° smoothing radius. Residuals that remain after the EOF method do exhibit S2 aliasing errors and a semiannual continental hydrology signal contained in the Global Land Data Assimilation Systems (GLDAS) model. Further analysis of the residual EOF signal revealed alternating track correlation patterns that are partially explained by the GRACE covariance matrix and the handling of nuisance parameters in the GRACE data processing.

  2. Atmospheric multidecadal variations in the North Atlantic realm: proxy data, observations, and atmospheric circulation model studies

    Directory of Open Access Journals (Sweden)

    K. Grosfeld

    2007-01-01

    Full Text Available We investigate the spatial and temporal characteristics of multidecadal climate variability in the North Atlantic realm, using observational data, proxy data and model results. The dominant pattern of multidecadal variability of SST depicts a monopolar structure in the North Atlantic during the instrumental period with cold (warm phases during 1900–1925 and 1970–1990 (1870–1890 and 1940–1960. Two atmospheric general circulation models of different complexity forced with global SST over the last century show SLP anomaly patterns from the warm and cold phases of the North Atlantic similar to the corresponding observed patterns. The analysis of a sediment core from Cariaco Basin, a coral record from the northern Red Sea, and a long-term sea level pressure (SLP reconstruction reveals that the multidecadal mode of the atmospheric circulation characterizes climate variability also in the pre-industrial era. The analyses of SLP reconstruction and proxy data depict a persistent atmospheric mode at least over the last 300 years, where SLP shows a dipolar structure in response to monopolar North Atlantic SST, in a similar way as the models' responses do. The combined analysis of observational and proxy data with model experiments provides an understanding of multidecadal climate modes during the late Holocene. The related patterns are useful for the interpretation of proxy data in the North Atlantic realm.

  3. Atmospheric multidecadal variations in the North Atlantic realm: proxy data, observations, and atmospheric circulation model studies

    Directory of Open Access Journals (Sweden)

    K. Grosfeld

    2006-08-01

    Full Text Available We investigate the spatial and temporal characteristics of multidecadal climate variability in the North Atlantic realm, using observational data, proxy data and model results. The dominant pattern of multidecadal variability of SST depicts a monopolar structure in the North Atlantic during the instrumental period with cold (warm phases during 1900–1925 and 1970–1990 (1870–1890 and 1940–1960. Two atmospheric general circulation models of different complexity forced with global SST over the last century show SLP anomaly patterns from the warm and cold phases of the North Atlantic similar to the corresponding observed patterns. The analysis of a sediment core from Cariaco Basin, a coral record from the northern Red Sea, and a long-term sea level pressure (SLP reconstruction reveals that the multidecadal mode of the atmospheric circulation characterizes climate variability also in the pre-industrial era. The analyses of SLP reconstruction and proxy data depict a persistent atmospheric mode at least over the last 300 years, where SLP shows a dipolar structure in response to monopolar North Atlantic SST, in a similar way as the models' responses do. The combined analysis of observational and proxy data with model experiments provides an understanding of multidecadal climate modes during the late Holocene. The related patterns are useful for the interpretation of proxy data in the North Atlantic realm.

  4. Whole earth telescope observations of the white dwarf G29-38 - Phase variations of the 615 second period

    International Nuclear Information System (INIS)

    An extensive set of high-speed photometric observations obtained with the Whole Earth Telescope network is used to show that the complex light curve of the ZZ Zeti (DAV) star G29-38 is dominated by a single, constant amplitude period of 615 s during the time span of these observations. The pulse arrival times for this period exhibit a systematic variation in phase readily explained by light-travel time effects produced by reflex orbital motion about an unseen companion. The best-fit model to the observations indicates a highly eccentric orbit, a period of 109 + or - 13 days and a minimum mass of 0.5 solar mass for the companion. 23 refs

  5. Topography caused by mantle density variations: observation-based estimates and models derived from tomography and lithosphere thickness

    Science.gov (United States)

    Steinberger, Bernhard

    2016-04-01

    Large-scale topography may be due to several causes, including (1) variations in crustal thickness and density structure, (2) oceanic lithosphere age differences, (3) subcrustal density variations in the continental lithosphere and (4) convective flow in the mantle beneath the lithosphere. The last contribution in particular may change with time and be responsible for continental inundations; distinguishing between these contributions is therefore important for linking Earth's history to its observed geological record. As a step towards this goal, this paper aims at such distinction for the present-day topography: the approach taken is deriving a `model' topography due to contributions (3) and (4), along with a model geoid, using a geodynamic mantle flow model. Both lithosphere thickness and density anomalies beneath the lithosphere are inferred from seismic tomography. Density anomalies within the continental lithosphere are uncertain, because they are probably due to variations in composition and temperature, making a simple scaling from seismic to density anomalies inappropriate. Therefore, we test a number of different assumptions regarding these. As a reality check, model topography is compared, in terms of both correlation and amplitude ratio, to `residual' topography, which follows from observed topography after subtracting contributions (1) and (2). The model geoid is compared to observations as well. Comparatively good agreement is found if there is either an excess density of ≈0.2 per cent in the lithosphere above ≈150 km depth, with anomalies below as inferred from tomography, or if the excess density is ≈0.4 per cent in the entire lithosphere. Further, a good fit is found for viscosity ≈1020 Pa s in the asthenosphere, increasing to ≈1023 Pa s in the lower mantle above D'. Results are quite dependent on which tomography models they are based on; for some recent ones, topography correlation is ≈0.6, many smaller scale features are matched

  6. Inter-observer variation in the interpretation of chest radiographs for pneumonia in community-acquired lower respiratory tract infections

    International Nuclear Information System (INIS)

    AIM: To assess inter-observer variation in the interpretation of chest radiographs of individuals with pneumonia versus those without pneumonia. MATERIALS AND METHODS: Chest radiographs of out-patients with a lower respiratory tract infection (LRTI) were assessed for the presence of infiltrates by radiologists from three local hospitals and were reassessed by one university hospital radiologist. Various measures of inter-observer agreement were calculated. RESULTS: The observed proportional agreement was 218 in 243 patients (89.7%). Kappa was 0.53 (moderate agreement) with a 95% confidence interval of 0.37 to 0.69. The observed positive agreement (59%) was much lower than for negative agreement (94%). Kappa was considerably lower, if chronic obstructive pulmonary disease was present (κ=0.20) or Streptococcus pneumoniae (κ=-0.29) was the infective agent. CONCLUSION: The overall inter-observer agreement adjusted for chance was moderate. Inter-observer agreement in cases with pneumonia was much worse than the agreement in negative (i.e. non-pneumonia) cases. A general practitioner's selection of patients with a higher chance of having pneumonia for chest radiography would thus not improve the observer agreement

  7. Atmospheric mercury observations from Antarctica: seasonal variation and source and sink region calculations

    Directory of Open Access Journals (Sweden)

    K. A. Pfaffhuber

    2012-04-01

    Full Text Available Long term atmospheric mercury measurements in the Southern Hemisphere are scarce and in Antarctica completely absent. Recent studies have shown that the Antarctic continent plays an important role in the global mercury cycle. Therefore, long term measurements of gaseous elemental mercury (GEM were initiated at the Norwegian Antarctic Research Station, Troll (TRS in order to improve our understanding of atmospheric transport, transformation and removal processes of GEM. GEM measurements started in February 2007 and are still ongoing, and this paper presents results from the first four years. The mean annual GEM concentration of 0.93 ± 0.19 ng m−3 is in good agreement with other recent southern-hemispheric measurements. Measurements of GEM were combined with the output of the Lagrangian particle dispersion model FLEXPART, for a statistical analysis of GEM source and sink regions. It was found that the ocean is a source of GEM to TRS year round, especially in summer and fall. On time scales of up to 20 days, there is little direct transport of GEM to TRS from Southern Hemisphere continents, but sources there are important for determining the overall GEM load in the Southern Hemisphere and for the mean GEM concentration at TRS. Further, the sea ice and marginal ice zones are GEM sinks in spring as also seen in the Arctic, but the Antarctic oceanic sink seems weaker. Contrary to the Arctic, a strong summer time GEM sink was found, when air originates from the Antarctic plateau, which shows that the summertime removal mechanism of GEM is completely different and is caused by other chemical processes than the springtime atmospheric mercury depletion events. The results were corroborated by an analysis of ozone source and sink regions.

  8. Atmospheric mercury observations from Antarctica: seasonal variation and source and sink region calculations

    Directory of Open Access Journals (Sweden)

    K. Aspmo Pfaffhuber

    2011-10-01

    Full Text Available Long term atmospheric mercury measurements in the Southern Hemisphere are scarce and in Antarctica completely absent. Recent studies have shown that the Antarctic continent plays an important role in the global mercury cycle. Therefore, long term measurements of gaseous elemental mercury (GEM were initiated at the Norwegian Antarctic Research Station, Troll (TRS in order to improve our understanding of atmospheric transport, transformations and removal processes of GEM. GEM measurements started in February 2007 and are still ongoing, and this paper presents results from the first four years. The mean annual GEM concentration was 0.93±0.19 ng m−3 and is in good agreement with other recent southern hemispheric measurements. Measurements of GEM were combined with the output of the Lagrangian particle dispersion model FLEXPART, for a statistical analysis of GEM source and sink regions. It was found that the ocean is a source of GEM to TRS year round, especially in summer and fall. None of the Southern Hemisphere continents contribute significantly to the direct transport of GEM to TRS, but they are important for determining the overall GEM load in the Southern Hemisphere and for the mean GEM concentration at TRS. Further, the sea ice and marginal ice zones are GEM sinks in spring as also seen in the Arctic, but the Antarctic oceanic sink seems weaker. Contrary to the Arctic, a strong summer time GEM sink was found, when air originates from the Antarctic Plateau, which shows that the summertime removal mechanism of GEM is completely different and is caused by other chemical processes than the springtime atmospheric mercury depletion events. The results were corroborated by an analysis of ozone source and sink regions.

  9. Variations of the mid-latitude ionosphere during strong geomagnetic storms. Observational results

    International Nuclear Information System (INIS)

    Complete text of publication follows. The ground-based ionosonde data obtained at Alma-Ata station [ψ=43.25degN, λ=76.92degE, Φ=33.47degN, L=1.44) are analyzed to study ionospheric responses at fourteen intense (Kp≥8) geomagnetic storms with storm sudden commencement (ssc). The collected data show that ionospheric responses to intensive geomagnetic storms (Dst<-100nT) are very complex with a great degree of variability; however, negative ionospheric disturbances are a common feature of the responses. The time delay between storm ssc and beginning of the negative ionospheric disturbances shows a tendency to be noticeably larger in winter events than the summer events. Positive ionospheric effects are observed during storm recovery phases or when the Dst almost fully recovered. The occurrence of the unusual for Alma-Ata location night E, F1 layers and auroral type r (retardation) sporadic Es layers is observed during developing or around main phases in Dst index. Employing the International Reference Ionosphere 2001 (IRI-2001), the nighttime E region electron density has been estimated for 'quiet' conditions on the epochs of the storm time. Direct comparison of the 'quiet' and 'storm' ionospheric data shows a very significant storm induced increase of the electron density in the 110 to 200 km altitude range that reaches a factor of about 10 at the 110km altitude. Interaction of precipitating energetic neutralized ring current particles with the upper atmosphere during geomagnetic disturbances is assumed to be a possible explanation for the observed night events at this latitude sector.

  10. Can we monitor groundwater head variation from space? Coupling ERS spaceborne microwave observations to groundwater dynamics

    Science.gov (United States)

    Sutanudjaja, E. H.; de Jong, S. M.; van Geer, F. C.; Bierkens, M. F. P.

    2012-04-01

    The objective of this study is to investigate whether the time series of a remote sensing based soil moisture product, referred as the European Remote Sensing Soil Water Index (ERS SWI), correlates to in-situ observations of groundwater heads; and can thus be used for groundwater head prediction. As a test-bed we used the Rhine-Meuse basin, where we have collected thousands of groundwater head time series. Here we performed a correlation analysis between the time series of groundwater heads and ERS SWI spatio-temporal maps of profile soil moisture content. Results show that there is a significant correlation between ERS SWI and groundwater heads. Correlation is strongest in areas with shallow groundwater. The correlation improves for most areas, including those with deep groundwater tables, if we account for the lag time (i.e. the response time of water from the upper unsaturated soil moisture zone to the saturated deeper groundwater bodies) by adding a time delay to the correlation analysis. We further investigated the possibility of using the ERS SWI to predict or estimate groundwater heads in two exercises in which we used the ERS SWI as the input of a transfer function-noise (TFN) model. (1) As a first exercise we focused on forecasting in time. For this, we calibrated the parameters of a TFN model to the head time series within the period 1995-2000 by embedding it in a Kalman filter algorithm. Once calibrated, we validated the TFN one-step-ahead forecasts for the period 2004-2007 in order to assess their prediction skill in time. (2) In a second exercise, we focused on spatio-temporal prediction. Here, we sampled the calibrated TFN parameters, derived in the first exercise, from a few selected head measurement locations. We then used these sampled TFN parameters to fit a spatial regression model with landscape attributes derived from a digital elevation model as input. The fitted regression model was subsequently used to estimate TFN parameters in all

  11. Can we monitor groundwater head variation from space? Coupling ERS spaceborne microwave observations to groundwater dynamics

    OpenAIRE

    Sutanudjaja, E.H.; Jong, S M; Van Geer, F. C.; M. F. P. Bierkens

    2012-01-01

    The objective of this study is to investigate whether the time series of a remote sensing based soil moisture product, referred as the European Remote Sensing Soil Water Index (ERS SWI), correlates to in-situ observations of groundwater heads; and can thus be used for groundwater head prediction. As a test-bed we used the Rhine-Meuse basin, where we have collected thousands of groundwater head time series. Here we performed a correlation analysis between the time series of groundwater heads a...

  12. Observer variation in measurements of waist-hip ratio and the abdominal sagittal diameter

    DEFF Research Database (Denmark)

    Rasmussen, M H; Andersen, T; Breum, Leif; Hilsted, J; Gøtzsche, P C

    1993-01-01

    In an out-patient weight loss study of 63 patients (54 female, 9 male), 53 completed a 16 week treatment with a low calorie diet and a 9 g/day fibre supplement. In these 53 patients, the average weight loss was 8.3 kg (s.e.m. 0.8). Waist-hip ratio (WHR) and abdominal sagittal diameter (SagD) were...... were 0.0% for WHR and 0.4% for SagD. It is concluded that there is no need to use several observers or repeated measurements of waist, hip and SagD in clinical anti-obesity trials....

  13. Regional scale variations of atmospheric CO2 and CH4 from satellite observation

    International Nuclear Information System (INIS)

    To identify the sources, sinks and changes of atmospheric CO2 and CH4, this study investigates the spatio-temporal changes of atmospheric CO2 and CH4 concentration on the regional scale by the satellite observations. In this paper, choosing the land region of China as the study area, we investigate the spatio-temporal changes of atmospheric CO2 and CH4 concentrations using the data of the CO2 dry air mixing ratio (XCO2), and the CH4 dry air mixing ratio (XCH4), retrieved by the Greenhouse Gases Observing Satellite (GOSAT) from Jan. 2010 to Dec. 2012. The results show that (1) both XCO2 and XCH4 show higher concentrations in southeastern regions than that in the northwestern, and tend to yearly increasing from 2010 to 2013; (2) XCO2 shows obvious seasonal change with higher values in the spring than that in summer. The seasonal peak-to-peak amplitude is 8 ppm and the annual growth is about 2 ppm. XCH4, however, does not show a seasonal change; (3) With regard to different land-use backgrounds, XCO2 shows larger concentrations over the areas of urban agglomeration than that over the grasslands and deserts, and XCH4 shows lower concentrations over deserts than that over the Yangtze River Delta region and Sichuan Basin

  14. VLT-UVES observations of the Balmer line variations of eta Carinae during the 2003 spectroscopic event

    CERN Document Server

    Weis, K; Bomans, D J; Davidson, K; Gull, T R; Humphreys, R M; Weis, Kerstin; Stahl, Otmar; Bomans, Dominik J.; Davidson, Kris; Gull, Theodore R.; Humphreys, Roberta M.

    2004-01-01

    We present high spectral resolution echelle observations of the Balmer line variations during the 2003.5 ``spectroscopic event'' of eta Carinae. Spectra have been recorded of both eta Carinae and the Homunculus at the FOS4 position in its SE lobe. This spot shows a reflected stellar spectrum which is less contaminated by nebular emission lines than ground-based observations of the central object itself. Our observations show that the spectroscopic event is much less pronounced at this position than when seen directly on eta Car using HST/STIS. Assuming that the reflected spectrum is indeed latitude dependent this indicates that the spectral changes during the event seen pole-on (FOS4) are different from those closer to the equator (directly on the star). In contrast to the spectrum of the star, the scattered spectrum of FOS4 always shows pronounced P Cygni absorption with little variation across the ``spectroscopic event''. After that event an additional high-velocity absorption component appears. The emissio...

  15. Transit Timing Observations from Kepler. V. Transit Timing Variation Candidates in the First Sixteen Months from Polynomial Models

    Science.gov (United States)

    Ford, Eric B.; Ragozzine, Darin; Rowe, Jason F.; Steffen, Jason H.; Barclay, Thomas; Batalha, Natalie M.; Borucki, William J.; Bryson, Stephen T.; Caldwell, Douglas A.; Fabrycky, Daniel C.; Gautier, Thomas N.; Holman, Matthew J.; Ibrahim, Khadeejah A.; Kjeldsen, Hans; Kinemuchi, Karen; Koch, David G.; Lissauer, Jack J.; Still, Martin; Tenenbaum, Peter; Uddin, Kamal; Welsh, William

    2012-09-01

    Transit timing variations provide a powerful tool for confirming and characterizing transiting planets, as well as detecting non-transiting planets. We report the results of an updated transit timing variation (TTV) analysis for 1481 planet candidates based on transit times measured during the first sixteen months of Kepler observations. We present 39 strong TTV candidates based on long-term trends (2.8% of suitable data sets). We present another 136 weaker TTV candidates (9.8% of suitable data sets) based on the excess scatter of TTV measurements about a linear ephemeris. We anticipate that several of these planet candidates could be confirmed and perhaps characterized with more detailed TTV analyses using publicly available Kepler observations. For many others, Kepler has observed a long-term TTV trend, but an extended Kepler mission will be required to characterize the system via TTVs. We find that the occurrence rate of planet candidates that show TTVs is significantly increased (~68%) for planet candidates transiting stars with multiple transiting planet candidates when compared to planet candidates transiting stars with a single transiting planet candidate.

  16. Galactic Edge Clouds I: Molecular Line Observations and Chemical Modelling of Edge Cloud 2

    CERN Document Server

    Ruffle, P M E; Roberts, H; Lubowich, D A; Henkel, C; Pasachoff, J M; Brammer, G

    2007-01-01

    Edge Cloud 2 (EC2) is a molecular cloud, about 35 pc in size, with one of the largest galactocentric distances known to exist in the Milky Way. We present observations of a peak CO emission region in the cloud and use these to determine its physical characteristics. We calculate a gas temperature of 20 K and a density of n(H2) ~ 10^4 cm^-3. Based on our CO maps, we estimate the mass of EC2 at around 10^4 M_sun and continuum observations suggest a dust-to-gas mass ratio as low as 0.001. Chemical models have been developed to reproduce the abundances in EC2 and they indicate that: heavy element abundances may be reduced by a factor of five relative to the solar neighbourhood (similar to dwarf irregular galaxies and damped Lyman alpha systems); very low extinction (Av < 4 mag) due to a very low dust-to-gas ratio; an enhanced cosmic ray ionisation rate; and a higher UV field compared to local interstellar values. The reduced abundances may be attributed to the low level of star formation in this region and are...

  17. Chemical differentiation, thermal evolution, and catastrophic overturn on Venus: Predictions and geologic observations

    Science.gov (United States)

    Head, James W.; Parmentier, E. M.; Hess, P. C.

    1993-01-01

    Observations from Magellan show that: (1) the surface of Venus is generally geologically young, (2) there is no evidence for widespread recent crustal spreading or subduction, (3) the crater population permits the hypothesis that the surface is in production, and (4) relatively few impact craters appear to be embayed by volcanic deposits suggesting that the volcanic flux has drastically decreased as a function of time. These observations have led to consideration of hypotheses suggesting that the geological history of Venus may have changed dramatically as a function of time due to general thermal evolution, and/or thermal and chemical evolution of a depleted mantle layer, perhaps punctuated by catastrophic overturn of upper layers or episodic plate tectonics. We have previously examined the geological implications of some of these models, and here we review the predictions associated with two periods of Venus history. Stationary thick lithosphere and depleted mantle layer, and development of regional to global development of regional to global instabilities, and compare these predictions to the geological characteristics of Venus revealed by Magellan.

  18. Suzaku Observations of Chemical Enrcihment History of Galaxy Cluster A3112

    Science.gov (United States)

    Ezer, Cemile; Nihal Ercan, Enise; Bulbul, Esra

    2016-07-01

    Galaxy clusters are known as grand reservoir of metals as their intracluster medium (ICM) are gradually enriched by supernova (SN) explosions. The azimuthal and spatial distributions of these metals from cluster's centre out to the virial radius are of vital importance since they record all the information on nucleosynthesis and chemical enrichment history of the formation. In this study, we present results from Suzaku observations of an archetypal cluster A3112 out to ˜1470 kpc. We additionally used overlapping Chandra observations to detect unresolved point sources. We studied the total number of SN explosions and the ratio of type Ia (SN Ia) to core-collapse (SNcc) integrated over the cluster lifetime by directly fitting the X-ray spectra. We investigated almost flat radial distribution of the relative contribution of SN Ia to SNcc and the percentage of SN Ia contributing to ICM is found to be 10%-25%. We also studied the α element (Mg, Si and S) abundances. Ultimate results will be presented and they are expected to unravel the enrichment type of the evolution.

  19. Variations observed in the respiratory activity of potato tubers (Solanum tuberosum L.) after a treatment with gamma radiation

    International Nuclear Information System (INIS)

    The present work studies the variations in the respiratory activity of irradiated and IPC treated potato tubers during a storage period of five months. By immediate effect of gamma radiation we can observe an increase in the oxygen consumption of the parenchyma in relation with the control tubers, such increase persists even fours months after gamma radiation. The respiratory activity is reduced in the IPC treated tubers. In the tissues cultivated in vitro the respiratory activity increases at the end of the cultivation period, not only in the control tissues but also in the irradiated ones, though this increase is greater in the control tissues. (Author) 15 refs

  20. Seasonal and Interannual Variations of Ice Sheet Surface Elevation at the Summit of Greenland: Observed and Modeled

    Science.gov (United States)

    Zwally, H. Jay; Jun, Li; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    Observed seasonal and interannual variations in the surface elevation over the summit of the Greenland ice sheet are modeled using a new temperature-dependent formulation of firn-densification and observed accumulation variations. The observed elevation variations are derived from ERS (European Remote Sensing)-1 and ERS-2 radar altimeter data for the period between April 1992 and April 1999. A multivariate linear/sine function is fitted to an elevation time series constructed from elevation differences measured by radar altimetry at orbital crossovers. The amplitude of the seasonal elevation cycle is 0.25 m peak-to-peak, with a maximum in winter and a minimum in summer. Inter-annually, the elevation decreases to a minimum in 1995, followed by an increase to 1999, with an overall average increase of 4.2 cm a(exp -1) for 1992 to 1999. Our densification formulation uses an initial field-density profile, the AWS (automatic weather station) surface temperature record, and a temperature-dependent constitutive relation for the densification that is based on laboratory measurements of crystal growth rates. The rate constant and the activation energy commonly used in the Arrhenius-type constitutive relation for firn densification are also temperature dependent, giving a stronger temperature and seasonal amplitudes about 10 times greater than previous densification formulations. Summer temperatures are most important, because of the strong non-linear dependence on temperature. Much of firn densification and consequent surface lowering occurs within about three months of the summer season, followed by a surface build-up from snow accumulation until spring. Modeled interannual changes of the surface elevation, using the AWS measurements of surface temperature and accumulation and results of atmospheric modeling of precipitation variations, are in good agreement with the altimeter observations. In the model, the surface elevation decreases about 20 cm over the seven years due

  1. Variations observed in the respiratory activity of potato tubers (Solanum tuberosum L.) after a treatment with gamma radiation

    International Nuclear Information System (INIS)

    The variations in the respiratory activity of irradiated and IPC treated potato tubers during a storage period of five months have been studied. By immediate effect of gamma radiation, an increase in the oxigen consumption of the parenchyma in relation with the control tubers has been observed. Such increase persits even four months after gamma radiation. The respiratory activity is reduced in the IPC treated tubers. In the tissues cultivated ''in vitro'' the respiratory activity increases at the end of the cultivation period, not only in the control tissues but also in the irradiated ones, though this increase is greater in the control tissues.(author)

  2. Ionospheric total electron content variations observed before earthquakes: Possible physical mechanism and modeling

    CERN Document Server

    Namgaladze, A A; Zakharenkova, I E; Shagimuratov, I I; Martynenko, O V

    2009-01-01

    The GPS derived anomalous TEC disturbances before earthquakes were discovered in the last years using global and regional TEC maps, measurements over individual stations as well as measurements along individual GPS satellite passes. For strong mid-latitudinal earthquakes the seismo-ionospheric anomalies look like local TEC enhancements or decreases located in the vicinity of the forthcoming earthquake epicenter In case of strong low-latitudinal earthquakes there are effects related with the modification of the equatorial F2-region anomaly: deepening or filling of the ionospheric electron density trough over the magnetic equator. We consider that the most probable reason of the NmF2 and TEC disturbances observed before the earthquakes is the vertical drift of the F2-region ionospheric plasma under the influence of the zonal electric field of seismic origin. To check this hypothesis, the model calculations have been carried out with the use of the Upper Atmosphere Model. The electric potential distribution at t...

  3. Earth's albedo variations 1998-2014 as measured from ground-based earthshine observations

    CERN Document Server

    Palle, E; Montanes-Rodriguez, P Pilar; Shumko, A; Gonzalez-Merino, B; Lombilla, C Martinez; Jimenez-Ibarra, F; Shumko, S; Sanroma, E; Hulist, A; Miles-Paez, P; Murgas, F; Nowak, G; Koonin, SE

    2016-01-01

    The Earth's albedo is a fundamental climate parameter for understanding the radiation budget of the atmosphere. It has been traditionally measured from space platforms, but also from the ground for sixteen years from Big Bear Solar Observatory by observing the Moon. The photometric ratio of the dark (earthshine) to the bright (moonshine) sides of the Moon is used to determine nightly anomalies in the terrestrial albedo, with the aim is of quantifying sustained monthly, annual and/or decadal changes. We find two modest decadal scale cycles in the albedo, but with no significant net change over the sixteen years of accumulated data. Within the evolution of the two cycles, we find periods of sustained annual increases, followed by comparable sustained decreases in albedo. The evolution of the earthshine albedo is in remarkable agreement with that from the CERES instruments, although each method measures different slices of the Earth's Bond albedo.

  4. Variations of dose rate observed by MSL/RAD in transit to Mars

    CERN Document Server

    Guo, Jingnan; Wimmer-Schweingruber, Robert F; Hassler, Donald M; Posner, Arik; Heber, Bernd; Köhler, Jan; Rafkin, Scot; Ehresmann, Bent; Appel, Jan K; Böhm, Eckart; Böttcher, Stephan; Burmeister, Sönke; Brinza, David E; Lohf, Henning; Martin, Cesar; Reitz, Günther

    2015-01-01

    Aims: To predict the cruise radiation environment related to future human missions to Mars, the correlation between solar modulation potential and the dose rate measured by the Radiation Assessment Detector (RAD) has been analyzed and empirical models have been employed to quantify this correlation. Methods: The instrument RAD, onboard Mars Science Laboratory's (MSL) rover Curiosity, measures a broad spectrum of energetic particles along with the radiation dose rate during the 253-day cruise phase as well as on the surface of Mars. With these first ever measurements inside a spacecraft from Earth to Mars, RAD observed the impulsive enhancement of dose rate during solar particle events as well as a gradual evolution of the galactic cosmic ray (GCR) induced radiation dose rate due to the modulation of the primary GCR flux by the solar magnetic field, which correlates with long-term solar activities and heliospheric rotation. Results: We analyzed the dependence of the dose rate measured by RAD on solar modulatio...

  5. Earth's albedo variations 1998-2014 as measured from ground-based earthshine observations

    Science.gov (United States)

    Palle, E.; Goode, P. R.; Montañés-Rodríguez, P.; Shumko, A.; Gonzalez-Merino, B.; Lombilla, C. Martinez; Jimenez-Ibarra, F.; Shumko, S.; Sanroma, E.; Hulist, A.; Miles-Paez, P.; Murgas, F.; Nowak, G.; Koonin, S. E.

    2016-05-01

    The Earth's albedo is a fundamental climate parameter for understanding the radiation budget of the atmosphere. It has been traditionally measured not only from space platforms but also from the ground for 16 years from Big Bear Solar Observatory by observing the Moon. The photometric ratio of the dark (earthshine) to the bright (moonshine) sides of the Moon is used to determine nightly anomalies in the terrestrial albedo, with the aim of quantifying sustained monthly, annual, and/or decadal changes. We find two modest decadal scale cycles in the albedo, but with no significant net change over the 16 years of accumulated data. Within the evolution of the two cycles, we find periods of sustained annual increases, followed by comparable sustained decreases in albedo. The evolution of the earthshine albedo is in remarkable agreement with that from the Clouds and the Earth's Radiant Energy System instruments, although each method measures different slices of the Earth's Bond albedo.

  6. Mutagenic effects of aerospace on Poa pratensis L.. Pt.1: Observation of leaves anatomical variation

    International Nuclear Information System (INIS)

    The dry seeds of Poa pratensis L. 'Nassau' were carried by 'Shenzhou No.3' spaceship and three mutants were screened based on presentational characters from the treated plants and asexual reproduced them as PM1, PM2 and PM3. Observation and investigation were made on the mutants in anatomical characters of the leaves. The results showed that the leaf surface structure and the ultrastructure of the mesophyllous cells changed. Compared to CK, the stoma density increased, but the stoma size decreased with the proportions of total stoma area of leaf area remained unchanged. The chloroplast concentrated to the middle of the cell with volume increase and the shape more roundness. The chloroplast of the mesophyllous cells in the white part of the green-white leaf of PM3 were dissolving or had dissolved. The number of the starch grain also increased in these mutants. (authors)

  7. Interrogating chemical variation via layer-by-layer SERS during biofouling and cleaning of nanofiltration membranes with further investigations into cleaning efficiency.

    Science.gov (United States)

    Cui, Li; Chen, Pengyu; Zhang, Bifeng; Zhang, Dayi; Li, Junyi; Martin, Francis L; Zhang, Kaisong

    2015-12-15

    Periodic chemical cleaning is an essential step to maintain nanofiltration (NF) membrane performance and mitigate biofouling, a major impediment in high-quality water reclamation from wastewater effluent. To target the important issue of how to clean and control biofouling more efficiently, this study developed surface-enhanced Raman spectroscopy (SERS) as a layer-by-layer tool to interrogate the chemical variations during both biofouling and cleaning processes. The fact that SERS only reveals information on the surface composition of biofouling directly exposed to cleaning reagents makes it ideal for evaluating cleaning processes and efficiency. SERS features were highly distinct and consistent with different biofouling stages (bacterial adhesion, rapid growth, mature and aged biofilm). Cleaning was performed on two levels of biofouling after 18 h (rapid growth of biofilm) and 48 h (aged biofilm) development. An opposing profile of SERS bands between biofouling and cleaning was observed and this suggests a layer-by-layer cleaning mode. In addition, further dynamic biochemical and infrastructural changes were demonstrated to occur in the more severe 48-h biofouling, resulting in the easier removal of sessile cells from the NF membrane. Biofouling substance-dependent cleaning efficiency was also evaluated using the surfactant sodium dodecyl sulfate (SDS). SDS appeared more efficient in cleaning lipid than polysaccharide and DNA. Protein and DNA were the predominant residual substances (irreversible fouling) on NF membrane leading to permanent flux loss. The chemical information revealed by layer-by-layer SERS will lend new insights into the optimization of cleaning reagents and protocols for practical membrane processes. PMID:26433006

  8. CSO and CARMA Observations of L1157. II. Chemical Complexity in the Shocked Outflow

    Science.gov (United States)

    Burkhardt, Andrew M.; Dollhopf, Niklaus M.; Corby, Joanna F.; Carroll, P. Brandon; Shingledecker, Christopher N.; Loomis, Ryan A.; Booth, Shawn Thomas; Blake, Geoffrey A.; Herbst, Eric; Remijan, Anthony J.; McGuire, Brett A.

    2016-08-01

    L1157, a molecular dark cloud with an embedded Class 0 protostar possessing a bipolar outflow, is an excellent source for studying shock chemistry, including grain-surface chemistry prior to shocks, and post-shock, gas-phase processing. The L1157-B1 and B2 positions experienced shocks at an estimated ∼2000 and 4000 years ago, respectively. Prior to these shock events, temperatures were too low for most complex organic molecules to undergo thermal desorption. Thus, the shocks should have liberated these molecules from the ice grain-surfaces en masse, evidenced by prior observations of SiO and multiple grain mantle species commonly associated with shocks. Grain species, such as OCS, CH3OH, and HNCO, all peak at different positions relative to species that are preferably formed in higher-velocity shocks or repeatedly shocked material, such as SiO and HCN. Here, we present high spatial resolution (∼3″) maps of CH3OH, HNCO, HCN, and HCO+ in the southern portion of the outflow containing B1 and B2, as observed with Combined Array for Research in Millimeter-Wave Astronomy. The HNCO maps are the first interferometric observations of this species in L1157. The maps show distinct differences in the chemistry within the various shocked regions in L1157B. This is further supported through constraints of the molecular abundances using the non-LTE code radex. We find that the east/west chemical differentiation in C2 may be explained by the contrast of the shock’s interaction with either cold, pristine material or warm, previously shocked gas, as seen in enhanced HCN abundances. In addition, the enhancement of the HNCO abundance toward the the older shock, B2, suggests the importance of high-temperature O-chemistry in shocked regions.

  9. A case for variational geomagnetic data assimilation: insights from a one-dimensional, nonlinear, and sparsely observed MHD system

    Directory of Open Access Journals (Sweden)

    A. Fournier

    2007-01-01

    Full Text Available Secular variations of the geomagnetic field have been measured with a continuously improving accuracy during the last few hundred years, culminating nowadays with satellite data. It is however well known that the dynamics of the magnetic field is linked to that of the velocity field in the core and any attempt to model secular variations will involve a coupled dynamical system for magnetic field and core velocity. Unfortunately, there is no direct observation of the velocity. Independently of the exact nature of the above-mentioned coupled system – some version being currently under construction – the question is debated in this paper whether good knowledge of the magnetic field can be translated into good knowledge of core dynamics. Furthermore, what will be the impact of the most recent and precise geomagnetic data on our knowledge of the geomagnetic field of the past and future? These questions are cast into the language of variational data assimilation, while the dynamical system considered in this paper consists in a set of two oversimplified one-dimensional equations for magnetic and velocity fields. This toy model retains important features inherited from the induction and Navier-Stokes equations: non-linear magnetic and momentum terms are present and its linear response to small disturbances contains Alfvén waves. It is concluded that variational data assimilation is indeed appropriate in principle, even though the velocity field remains hidden at all times; it allows us to recover the entire evolution of both fields from partial and irregularly distributed information on the magnetic field. This work constitutes a first step on the way toward the reassimilation of historical geomagnetic data and geomagnetic forecast.

  10. Exploring Anticorrelations and Light Element Variations in Northern Globular Clusters Observed by the APOGEE Survey

    CERN Document Server

    Meszaros, Szabolcs; Shetrone, Matthew; Lucatello, Sara; Troup, Nicholas W; Bovy, Jo; Cunha, Katia; Garcia-Hernandez, Domingo A; Overbeek, Jamie C; Prieto, Carlos Allende; Beers, Timothy C; Frinchaboy, Peter M; Perez, Ana E Garcia; Hearty, Fred R; Holtzman, Jon; Majewski, Steven R; Nidever, David L; Schiavon, Ricardo P; Schneider, Donald P; Sobeck, Jennifer S; Smith, Verne V; Zamora, Olga; Zasowski, Gail

    2015-01-01

    We investigate the light-element behavior of red giant stars in Northern globular clusters (GCs) observed by the SDSS-III Apache Point Observatory Galactic Evolution Experiment (APOGEE). We derive abundances of nine elements (Fe, C, N, O, Mg, Al, Si, Ca, and Ti) for 428 red giant stars in 10 globular clusters. The intrinsic abundance range relative to measurement errors is examined, and the well-known C-N and Mg-Al anticorrelations are explored using an extreme-deconvolution code for the first time in a consistent way. We find that Mg and Al drive the population membership in most clusters, except in M107 and M71, the two most metal-rich clusters in our study, where the grouping is most sensitive to N. We also find a diversity in the abundance distributions, with some clusters exhibiting clear abundance bimodalities (for example M3 and M53) while others show extended distributions. The spread of Al abundances increases significantly as cluster average metallicity decreases as previously found by other works, ...

  11. Satellite Observations of Groundwater Storage Variations and Their Application for Water Security Monitoring

    Science.gov (United States)

    Rodell, M.; Famiglietti, J. S.; Li, B.; Kumar, S.; Reager, J. T., II

    2015-12-01

    Fresh water demand is steadily increasing around the world due to population growth, economic development, and people's desire for a "western" lifestyle and diet. Where surface water availability is not sufficient or consistent, groundwater is often the resource of choice for agriculture, industry, and municipal and domestic uses. However, unlike lake levels, aquifer levels are unseen and are not easily measured. This can create the illusion of an infinite water source and impede efforts to monitor and conserve groundwater. Moreover, even where depth-to-water measurements do exist, they often are not digitized, centralized, and accessible. The GRACE satellites are a partial solution to this problem, enabling space-based estimates of groundwater variability at regional scales that are not limited by political boundaries. Here we discuss emerging trends in groundwater storage around the world based on GRACE observations and how they can be combined with other information in order attribute these apparent trends and support sub-regional scale analyses of changing groundwater availability.

  12. Seasonal variations of physical and chemical erosion: A three-year survey of the Rhone River (France)

    Science.gov (United States)

    Ollivier, P.; Hamelin, B.; Radakovitch, O.

    2010-02-01

    Numerous studies of weathering fluxes have been carried out on major world rivers during the last decade, to estimate CO 2 consumption rates, landscape evolution and global erosion rates. For obvious logistical reasons, most of these studies were based on large scale investigations carried out on short timescales. By comparison, much less effort has been devoted to long term monitoring, as a means to verify the temporal variability of the average characteristics, their trends, and the representativeness of short-term investigations. Here we report the results of a three-year survey (November 2000 to December 2003) of the major and trace element composition of dissolved and suspended matter in the lower Rhone River (France), the largest river of the Mediterranean area. Subsurface water samples were collected in Arles, about 48 km upstream of the estuary, twice a month routinely, and at higher frequency during flood events. During each flood event, the suspended particulate matter (SPM) show the usual trend of clockwise hysteresis with higher SPM concentrations on the rising limb of the flood than at the same discharge on the falling limb. We show that the annual average SPM flux of the Rhone River to the Mediterranean Sea (7.3 ± 0.6 × 10 6 tons yr -1) was largely controlled by the flood events (83% of the solid discharge occurred in less than 12% of the time), and that the precision on the total output flux depends strongly on the precise monitoring of SPM variations during the floods. The chemical composition of water and SPM are characterized by the predominance of Ca 2+ due to the abundance of carbonate rocks in the Rhone watershed. Chemical budgets have been calculated to derive the contributions of atmospheric deposition, carbonate, silicate and evaporite weathering, and anthropogenic inputs. The chemical weathering rate of carbonates is estimated to be 89 ± 5 t km -2 yr -1 compared to 14.4 ± 3 t km -2 yr -1 from silicates. By contrast, the physical erosion

  13. Study of shear wave attenuation field variations in Central Asia region using records of nuclear and chemical explosions at the Semipalatinsk Test Site

    International Nuclear Information System (INIS)

    The temporal variations of amplitude ratio of Lg and Pg, Lg and P waves were studied using the 1964-2000 records of more than 200 underground nuclear and chemical calibration explosions obtained at the Northern Tien Shan TLG station, KURK station (Eastern Kazakhstan), BRVK (Kokchetav Massif), GRM (Southern Tien Shan) located at epicentral distances of 77-1400 km. Variations in this parameter with time are shown to be significantly different for different paths. The spatial-temporal variations of the seismic wave attenuation field are presumably associated with the ascent of juvenile fluids through large deep faults. (author)

  14. The effects of the variations of turbulence parameters on the observable turbulence statistics

    Science.gov (United States)

    Ding, S. Y.

    2016-06-01

    In order to study how the statistical properties of the observational quantities of the turbulent molecular cloud models vary with different turbulence parameters, I use the artificially generated random numerical models based on Gaussian fields created by the code PYFC with different values of the 1D density Fourier spectral index βn, the turbulence driving parameter, i.e. the b parameter and the 1D Fourier velocity power spectral index βv. Then I calculate the line profiles of 13CO emission on every sight line. I derive the statistical properties of column density N, line intensity W, peak intensity Tpeak and velocity dispersion Vrms on every sight line. I discover that as βn increases, (1) the standard deviations σln (N/) and σln (W/) of the logarithmic column density ln (N/) and the logarithmic integrated intensity ln (W/) increase; (2) the number of the low Tpeak values becomes larger; (3) the probability distribution function (PDF) of Vrms inclines to left a little. As the b parameter increases, (1) the values of both σln (N/) and σln (W/) increase; (2) the numbers of both the low Tpeak values and the saturated Tpeak values become larger; (3) the PDF of Vrms inclines to left obviously. As βv increases, (1) the PDF of ln (W/) remains generally unchanged; (2) the PDF of Tpeak remains generally unchanged; (3) the PDF of Vrms inclines to left obviously. I also discuss the relationship among σN/, Mach number, the b parameter and βn.

  15. Recent observations of dynamic variations of the thermosphere and ionosphere by the Optical Mesosphere Thermosphere Imagers (OMTIs)

    Science.gov (United States)

    Shiokawa, Kazuo; Otsuka, Yuichi; Oyama, Shin-ichiro; Lakshmi Narayanan, Viswanathan; Ceren Moral, Aysegul

    2016-07-01

    The Optical Mesosphere Thermosphere Imagers (OMTIs) consist of fourteen all-sky cooled-CCD imagers, five Fabry-Perot interferometers (FPIs), three meridian scanning photometers, and four airglow temperature photometers. They measure two-dimensional pattern, Doppler wind, and temperature through airglow emissions from oxygen (wavelength: 557.7 nm) and OH (near infrared band) in the mesopause region (80-100 km) and from oxygen (630.0 nm) in the thermosphere/ionosphere (200-300 km). They are in automatic operation at 14 stations at Australia, Indonesia, Thailand, far-east Russia, Japan, Canada, Hawaii, Norway, and Nigeria. Station information and quick look plots are available at http://stdb2.stelab.nagoya-u.ac.jp/omti/. In this presentation we show recent observations of the dynamical variations of the thermosphere and ionosphere observed by OMTIs at various latitudes from the equator to the auroral zone.

  16. Observations of Seasonal Variations in Sea Bottom Temperature and Salinity in Bykovsky Bay in the Laptev Sea

    Science.gov (United States)

    Overduin, P. P.; Grigoriev, M. N.; Kopsch, C.

    2009-04-01

    Following inundation due to coastal erosion or increasing relative sea level, flooded permafrost is separated from the atmosphere by sea ice and water. The boundary condition for further permafrost evolution is given by seabed salinity and temperature. Few records of seasonal variations in these parameters exist, limiting our ability to predict the speed of subsea peramfrost degradation, or to correlate borehole observations with near-shore processes. For subsea permafrost, seabottom temperature drives sediment warming and variations in salinity can increase the rate of penetration of the seawater salt front into the sediment. A borehole transect drilled in 1983 in the nearshore zone off Mamontovy Khayata on the Bykovsky Peninsula in the Laptev Sea resulted in a description of subsea sediment temperature and the inclination of the top of the ice-bearing permafrost perpendicular to the coast out to a distance of 3 km. Before erosion, the landscape at Mamontovy Khayata is composed of ice-rich periglacial deposits down to and beneath current sea level, most of which are removed during erosion. Thermokarst features dominate the landscape and affect coastal bluff height and the resilience of sediments to coastal erosion and abrasion. We installed dataloggers on the seabed in 2007 to measure bottom water temperature and salinity at hourly intervals. Temperature variations are higher than expected, and together with salinity demonstrate the changing seasonal importance of warm, fresh river water and colder, saltier sea water that has been observed elsewhere. During winter, bottom water temperatures stabilize at the freezing point, but rise slowly during the winter, during a period of increasing salinity. We propose that this warming corresponds to the loss of heat from the underlying sediment. We compare integrated rates of warming of subsea and terrestrial permafrost and estimate the increase in the rate of subsea permafrost thermal degradation after inundation.

  17. The Transiting System GJ1214: High-Precision Defocused Transit Observations and a Search for Evidence of Transit Timing Variation

    CERN Document Server

    Harpsøe, K B W; Hinse, T C; Jørgensen, U G; Mancini, L; Southworth, J; Alsubai, K A; Bozza, V; Browne, P; Burgdorf, M J; Novati, S Calchi; Dodds, P; Dominik, M; Finet, F; Gerner, T; Hundertmark, M; Kains, N; Kerins, E; Liebig, C; Mathiasen, M; Nesvorný, D; Nikolov, N; Penny, M T; Proft, S; Rahvar, S; Ricci, D; Sahu, K C; Scarpetta, G; Schäfer, S; Schönebeck, F; Snodgrass, C; Skottfelt, J; Surdej, J; Tregloan-Reed, J; Wertz, O

    2012-01-01

    Aims: We present 11 high-precision photometric transit observations of the transiting super-Earth planet GJ1214b. Combining these data with observations from other authors, we investigate the ephemeris for possible signs of transit timing variations (TTVs) using a Bayesian approach. Methods: The observations were obtained using telescope-defocusing techniques, and achieve a high precision with random errors in the photometry as low as 1mmag per point. To investigate the possibility of TTVs in the light curve, we calculate the overall probability of a TTV signal using Bayesian methods. Results: The observations are used to determine the photometric parameters and the physical properties of the GJ1214 system. Our results are in good agreement with published values. Individual times of mid-transit are measured with uncertainties as low as 10s, allowing us to reduce the uncertainty in the orbital period by a factor of two. Conclusions: A Bayesian analysis reveals that it is highly improbable that the observed tra...

  18. Improving our knowledge of the rapid geomagnetic field intensity variation observed in Europe around 800 AD

    Science.gov (United States)

    Gómez-Paccard, M.; Chauvin, A.; Lanos, P.; Dufresne, P.; Kovacheva, M.; Hill, M. J.; Beamud, E.; Gutiérrez-Lloret, S.; Cañavate, V.; Blain, S.; Bouvier, A.; Oberlin, C.; Guibert, P.; Sapin, C.; Pringent, D.

    2011-12-01

    Available European data indicate that during the past 2500 years there have been periods of rapid intensity geomagnetic fluctuations interspersed with periods of little change. The challenge now is to precisely describe these rapid changes. The aim of this study is to obtain an improved description of the sharp geomagnetic intensity change that took place in Western Europe around 800 yrs AD as well as to investigate if this peak is observed at a continental scale. For this purpose 13 precisely dated early medieval Spanish pottery fragments, 4 archeological French kilns and a 3 collections of bricks used for the construction of different historical buildings from France and with ages ranging between 330 to 1290 AD have been studied. The material collected has been dated by archeological/historical constraints together with radiocarbon,thermoluminiscence (TL) and archeomagentic analysis. From classical Thellier experiments including TRM anisotropy and cooling rate corrections upon archeointensity estimates and conducted on 164 specimens (119 of them giving reliable results) ten new high-quality mean intensities have been obtained. The new intensity data together with a selection of the most reliable data from Western Europe have been relocated to the latitude of Paris and confirm the existence of an intensity maxima of ~85 μT centred at ~850 AD and related to intensity changes up to 20 μT per century. The results also indicate that a previous abrupt intensity change (reaching a maximum value of ~ 90 μT) took place in Western Europe around 650 AD. A selection of high-quality intensity data from Bulgaria, Italy and Greece indicate a very similar intensity trend for Eastern Europe. Although available data indicate that the duration of such periods of high intensities may be of less than one century more data are needed to infer the exact duration of these maximums. A comparison between the selected data and regional and global geomagnetic field models indicates that

  19. On the mechanism of seasonal and solar cycle NmF2 variations: A quantitative estimate of the main parameters contribution using incoherent scatter radar observations

    OpenAIRE

    Mikhailov, A. V.; Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, Troitsk, Moscow Region, Russia; Perrone, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia

    2011-01-01

    Seasonal (winter/summer) and solar cycle NmF2 variations as well as summer saturation effect in NmF2 have been analyzed using Millstone Hill incoherent scatter radar (ISR) daytime observations. A self‐consistent approach to the Ne(h) modeling has been applied to extract from ISR observations a consistent set of main aeronomic parameters and to estimate their quantitative contribution to the observed NmF2 variations. The retrieved aeronomic parameters are independent of uncertai...

  20. Airborne observations of formic acid using a chemical ionization mass spectrometer

    Directory of Open Access Journals (Sweden)

    M. Le Breton

    2012-12-01

    Full Text Available The first airborne measurements of formic acid mixing ratios over the United Kingdom were measured on the FAAM BAe-146 research aircraft on 16 March 2010 with a chemical ionization mass spectrometer using I reagent ions. The I ionization scheme was able to measure formic acid mixing ratios at 1 Hz in the boundary layer.

    In-flight standard addition calibrations from a formic acid source were used to determine the instrument sensitivity of 35 ± 6 ion counts pptv−1 s−1 and a limit of detection of 25 pptv. Routine measurements were made through a scrubbed inlet to determine the instrumental background. Three plumes of formic acid were observed over the UK, originating from London, Humberside and Tyneside. The London plume had the highest formic acid mixing ratio throughout the flight, peaking at 358 pptv. No significant correlations of formic acid with NOx and ozone were found, but a positive correlation was observed between CO and HCOOH within the two plumes where coincident data were recorded.

    A trajectory model was employed to determine the sources of the plumes and compare modelled mixing ratios with measured values. The model underestimated formic acid concentrations by up to a factor of 2. This is explained by missing sources in the model, which were considered to be both primary emissions of formic acid of mainly anthropogenic origin and a lack of precursor emissions, such as isoprene, from biogenic sources, whose oxidation in situ would lead to formic acid formation.

  1. A Wavelet based Suboptimal Kalman Filter for Assimilation of Stratospheric Chemical Tracer Observations

    Science.gov (United States)

    Tangborn, Andrew; Auger, Ludovic

    2003-01-01

    A suboptimal Kalman filter system which evolves error covariances in terms of a truncated set of wavelet coefficients has been developed for the assimilation of chemical tracer observations of CH4. This scheme projects the discretized covariance propagation equations and covariance matrix onto an orthogonal set of compactly supported wavelets. Wavelet representation is localized in both location and scale, which allows for efficient representation of the inherently anisotropic structure of the error covariances. The truncation is carried out in such a way that the resolution of the error covariance is reduced only in the zonal direction, where gradients are smaller. Assimilation experiments which last 24 days, and used different degrees of truncation were carried out. These reduced the covariance size by 90, 97 and 99 % and the computational cost of covariance propagation by 80, 93 and 96 % respectively. The difference in both error covariance and the tracer field between the truncated and full systems over this period were found to be not growing in the first case, and growing relatively slowly in the later two cases. The largest errors in the tracer fields were found to occur in regions of largest zonal gradients in the constituent field. This results indicate that propagation of error covariances for a global two-dimensional data assimilation system are currently feasible. Recommendations for further reduction in computational cost are made with the goal of extending this technique to three-dimensional global assimilation systems.

  2. An electromagnetic sounding experiment in Germany using the vertical gradient of geomagnetic variations observed in a deep borehole

    Science.gov (United States)

    Schmucker, Ulrich; Spitzer, Klaus; Steveling, Erich

    2009-09-01

    We have recorded for 13 d, geomagnetic variations simultaneously on the Earth's surface and in a borehole at 832 m depth straight below, with a sampling rate of 1 Hz. In addition, geoelectric variations were observed at the same site near Bad Königshofen in Frankonia, Germany. The penetrated moderately conductive Triassic sediments lie above highly resistive Permian deposits. A presumably crystalline basement begins at 1500-1900 m depth. The purpose of the experiment is to determine the skin effect of geomagnetic variations and to derive from it the equivalent to the magnetotelluric (MT) surface impedance, using the vertical gradient (VG) method of electromagnetic (EM) sounding. In this way, we were able to reproduce all four elements of the MT impedance tensor, except for an unexplained but consistent downward shift of VG phases against MT phases by roughly 15° for the two off-diagonal elements. Hence, our tensor evaluation goes beyond the common practice, to express the skin effect by a single VG transfer function in response to a layered structure. The otherwise good agreement of VG and MT results implies that at our test site, the MT impedance tensor is largely distortion-free and that, for example, its pronounced anisotropy should be regarded as a genuine characteristic of the EM response for a laterally non-uniform or possibly anisotropic deep structure. The drilling site lies within the range of a widespread induction anomaly. We have observed the resulting variations of the vertical magnetic component at the surface and in the borehole and found them to be identical. The thus established absence of a skin effect for the vertical component allows us to treat the sedimentary layer down to the depth of the borehole instrument as a thin sheet, and the pertinent thin-sheet approximation for EM induction forms the basis of our analysis. We have derived the required estimate of conductance from the skin effect of horizontal components, noting that this estimate

  3. Parallel Computing of a Variational Data Assimilation Model for GPS/MET Observation Using the Ray-Tracing Method

    Institute of Scientific and Technical Information of China (English)

    张昕; 刘月巍; 王斌; 季仲贞

    2004-01-01

    The Spectral Statistical Interpolation (SSI) analysis system of NCEP is used to assimilate meteorological data from the Global Positioning Satellite System (GPS/MET) refraction angles with the variational technique. Verified by radiosonde, including GPS/MET observations into the analysis makes an overall improvement to the analysis variables of temperature, winds, and water vapor. However, the variational model with the ray-tracing method is quite expensive for numerical weather prediction and climate research. For example, about 4 000 GPS/MET refraction angles need to be assimilated to produce an ideal global analysis. Just one iteration of minimization will take more than 24 hours CPU time on the NCEP's Gray C90 computer. Although efforts have been taken to reduce the computational cost, it is still prohibitive for operational data assimilation. In this paper, a parallel version of the three-dimensional variational data assimilation model of GPS/MET occultation measurement suitable for massive parallel processors architectures is developed. The divide-and-conquer strategy is used to achieve parallelism and is implemented by message passing. The authors present the principles for the code's design and examine the performance on the state-of-the-art parallel computers in China. The results show that this parallel model scales favorably as the number of processors is increased. With the Memory-IO technique implemented by the author, the wall clock time per iteration used for assimilating 1420 refraction angles is reduced from 45 s to 12 s using 1420 processors. This suggests that the new parallelized code has the potential to be useful in numerical weather prediction (NWP) and climate studies.

  4. Low-frequency variations in surface atmospheric humidity, temperature, and precipitation: Inferences from reanalyses and monthly gridded observational data sets

    Science.gov (United States)

    Simmons, A. J.; Willett, K. M.; Jones, P. D.; Thorne, P. W.; Dee, D. P.

    2010-01-01

    Evidence is presented of a reduction in relative humidity over low-latitude and midlatitude land areas over a period of about 10 years leading up to 2008, based on monthly anomalies in surface air temperature and humidity from comprehensive European Centre for Medium-Range Weather Forecasts reanalyses (ERA-40 and ERA-Interim) and from Climatic Research Unit and Hadley Centre analyses of monthly station temperature data (CRUTEM3) and synoptic humidity observations (HadCRUH). The data sets agree well for both temperature and humidity variations for periods and places of overlap, although the average warming over land is larger for the fully sampled ERA data than for the spatially and temporally incomplete CRUTEM3 data. Near-surface specific humidity varies similarly over land and sea, suggesting that the recent reduction in relative humidity over land may be due to limited moisture supply from the oceans, where evaporation has been limited by sea surface temperatures that have not risen in concert with temperatures over land. Continental precipitation from the reanalyses is compared with a new gauge-based Global Precipitation Climatology Centre (GPCC) data set, with the combined gauge and satellite products of the Global Precipitation Climatology Project (GPCP) and the Climate Prediction Center (CPC), Merged Analysis of Precipitation (CMAP), and with CPC's independent gauge analysis of precipitation over land (PREC/L). The reanalyses agree best with the new GPCC and latest GPCP data sets, with ERA-Interim significantly better than ERA-40 at capturing monthly variability. Shifts over time in the differences among the precipitation data sets make it difficult to assess their longer-term variations and any link with longer-term variations in humidity.

  5. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  6. High frequency variations of the main magnetic field: convergence of observations and theory (Petrus Peregrinus Medal Lecture)

    Science.gov (United States)

    Jault, Dominique

    2013-04-01

    Understanding the main magnetic field variations has been hindered by the discrepancy between the periods (from months to years) of the simplest linear wave phenomena and the relatively long time intervals (10 to 100 years) over which magnetic field changes can be confidently monitored. A theoretical description of short-period waves within the Earth's fluid core is at hand. Quasi-geostrophic inertial waves (akin to Rossby waves in the atmosphere) are slightly modified in the presence of magnetic fields and torsional oscillations consist of differential motion between coaxial rigid cylindrical annuli. Torsional oscillations are sensitive to the whole magnetic field that they shear in the course of their propagation. From their modelling, we have thus gained an estimate for the magnetic field strength in the core interior. There is now ongoing work to extend the theoretical framework to longer times. Furthermore, data collected from the Swarm constellation of three satellites to be launched this year by ESA will permit to better separate the internal and external magnetic signals. We may thus dream to detect quasi-geostrophic inertial waves. As the spectral ranges of theoretical models and observations begin to overlap, we can now go beyond the understanding of the magnetic field variations as the juxtaposition of partial models, arranged as a set of nested Matryoshka dolls. This talk will give illustrations for this statement, among which the question of induction in the lower mantle.

  7. Chemical Evolution in Sersic 159-03 Observed with Xmm-Newton

    Energy Technology Data Exchange (ETDEWEB)

    de Plaa, Jelle; Werner, N.; Bykov, A.M.; Kaastra, J.S.; Mendez, M.; Vink, J.; Bleeker, J.A.M.; Bonamente, M.; Peterson, J.R.; /SRON, Utrecht /Utrecht, Astron. Inst.

    2006-03-10

    Using a new long X-ray observation of the cluster of galaxies Sersic 159-03 with XMM-Newton, we derive radial temperature and abundance profiles using single- and multi-temperature models. The fits to the EPIC and RGS spectra prefer multi-temperature models especially in the core. The radial profiles of oxygen and iron measured with EPIC/RGS and the line profiles in RGS suggest that there is a dip in the O/Fe ratio in the centre of the cluster compared to its immediate surroundings. A possible explanation for the large scale metallicity distribution is that SNIa and SNII products are released in the ICM through ram-pressure stripping of in-falling galaxies. This causes a peaked metallicity distribution. In addition, SNIa in the central cD galaxy enrich mainly the centre of the cluster with iron. This excess of SNIa products is consistent with the low O/Fe ratio we detect in the centre of the cluster. We fit the abundances we obtain with yields from SNIa, SNII and Population-III stars to derive the clusters chemical evolution. We find that the measured abundance pattern does not require a Population-III star contribution. The relative contribution of the number of SNIa with respect to the total number of SNe which enrich the ICM is about 25-50%. Furthermore, we discuss the possible presence of a non-thermal component in the EPIC spectra. A potential source of this non-thermal emission can be inverse-Compton scattering between Cosmic Microwave Background (CMB) photons and relativistic electrons, which are accelerated in bow shocks associated with ram-pressure stripping of in-falling galaxies.

  8. Seasonal and Global Variations of Water Vapor and High Clouds Observed with MODIS near-IR Channels

    Science.gov (United States)

    Gao, Bo-Cai; Yang, Ping; Kaufman, Yoram J.; Wiscombe, Warren J.; Lau, William K. M. (Technical Monitor)

    2002-01-01

    The NASA Moderate Resolution Imaging Spectrometer (MODIS) on the Terra Spacecraft has been collecting scientific data since February of 2000. MODIS is a major facility instrument for remote sensing of the atmosphere, land surfaces, and ocean color. On the MODIS instruments, there are five channels located within and around the .0.94 micron water vapor band absorption region for remote sensing of atmospheric water vapor. There is also a channel located at 1.375 micron for detecting thin cirrus clouds. We will describe the basic principles for using these near-IR channels for remote sensing of water vapor and high clouds. Based on our analysis of two years# measurements with these channels, we have found that reliable observations of water vapor and high clouds on regional and global scales can be made. We will present results on daily, seasonal and annual variations of water vapor and high clouds.

  9. Transit Timing Observations from Kepler: VI. Transit Timing Variation Candidates in the First Seventeen Months from Polynomial Models

    CERN Document Server

    Ford, Eric B; Rowe, Jason F; Steffen, Jason H; Barclay, Thomas; Batalha, Natalie M; Borucki, William J; Bryson, Stephen T; Caldwell, Douglas A; Fabrycky, Daniel C; Gautier, Thomas N; Holman, Matthew J; Ibrahim, Khadeejah A; Kjeldsen, Hans; Kinemuchi, Karen; Koch, David G; Lissauer, Jack J; Still, Martin; Tenenbaum, Peter; Uddin, Kamal; Welsh, William

    2012-01-01

    Transit timing variations provide a powerful tool for confirming and characterizing transiting planets, as well as detecting non-transiting planets. We report the results an updated TTV analysis for 822 planet candidates (Borucki et al. 2011; Batalha et al. 2012) based on transit times measured during the first seventeen months of Kepler observations (Rowe et al 2012). We present 35 TTV candidates (4.1% of suitable data sets) based on long-term trends and 153 mostly weaker TTV candidates (18% of suitable data sets) based on excess scatter of TTV measurements about a linear ephemeris. We anticipate that several of these planet candidates could be confirmed and perhaps characterized with more detailed TTV analyses using publicly available Kepler observations. For many others, Kepler has observed a long-term TTV trend, but an extended Kepler mission will be required to characterize the system via TTVs. We find that the occurence rate of planet candidates that show TTVs is significantly increased (~60%-76%) for p...

  10. Spatial variation of chemical composition and sources of submicron aerosol in Zurich: factor analysis of mobile aerosol mass spectrometer data

    Directory of Open Access Journals (Sweden)

    C. Mohr

    2011-04-01

    Full Text Available Mobile measurements of PM1 (PM with an aerodynamic diameter D<1 μm chemical composition using a quadrupole aerosol mass spectrometer and a multi-angle absorption photometer were performed using the PSI mobile laboratory during winter 2007/2008 and December 2008 in the metropolitan area of Zurich, Switzerland. Positive matrix factorization (PMF applied to the organic fraction of PM1 yielded 3 factors: Hydrocarbon-like organic aerosol (HOA related to traffic emissions; organic aerosol from wood burning for domestic heating purposes (WBOA; and oxygenated organic aerosol (OOA, assigned to secondary organic aerosol formed by oxidation of volatile precursors. The spatial variation of the chemical composition of PM1 shows a uniform distribution throughout the city: for primary emissions, road traffic is important along major roads (varying between 7 and 14% of PM1 for different sites within the city, but overall, domestic wood burning is more important for the organic aerosol concentrations in Zurich during winter time (varying between 8–15% of PM1 for different sites within the city. OOA makes up the largest fraction of organic aerosol (44% on average. A new method, based on simultaneous on-road mobile and stationary background measurements and using the ratio of on-road sulfate to stationary sulfate to correct for small-scale dynamic effects, allows for the separation of PM1 emitted or produced locally and the PM1 from the regional background. It could be shown that especially during thermal inversions over the Swiss plateau, regional background concentrations contribute substantially to particulate number concentrations (60% on average as well as to the concentrations of PM1 components (on average 60% for black carbon and HOA, over 97% for WBOA and OOA, and more than 94% for the measured inorganic components in downtown Zurich. The results emphasize, on

  11. Temporal gravity variations observed with the superconducting gravimeter at Metsähovi, Finland: interpreted by local hydrological sensors

    Science.gov (United States)

    Virtanen, H.; Mäkinen, J.; Raja-Halli, A.; Hokkanen, T.; Mäkinen, R. P.

    2012-04-01

    Metsähovi is a fundamental geodetic station with multiple observation techniques, including a superconducting gravimeter (SG). The SG no. T020 has been operating continuously at Metsähovi since August 1994. After corrections for known time-variable gravity effects, such as tides, atmosphere and the Baltic Sea are made, the remaining gravity residual (8 microgals peak-to-peak) is mostly due to variation in terrestrial water storage. The detection threshold of the SG corresponds to the attraction a hypothetical Bouguer slab of water 1-2 mm thick that extends below the instrument as well. The local hydrological effects in gravity are generated by the attractions: local water storage in the fractures of the crystalline bedrock, local water storage in sediments, local snow on the ground and on the laboratory roof. In addition, by the loading and attraction by regional and global water storage. If we want to use record of the SG for discriminating between different regional/continental hydrological models, or for validating GRACE observations, physical modeling of the local effects is required. The station stands on bedrock and surrounding sediments are thin (0.2 - to 4 meters) but geologically quite complex. Since 1994 station is equipped with two borehole wells in the crystalline bedrock. In 2006 two arrays of Time Domain Reflectometer sensors of soil moisture were installed by the Finnish Environment Institute. In 2008-2009 several new instruments were installed within 100-150 m distance from the SG: Ten additional capacitive arrays for soil moisture, a 20 x 20 meter grid of 21 x 21=441 probes for soil resistivity. For observing groundwater level in the sediments, we lowered 11 tubes down to the bedrock surface. For radiometric measurements of soil moisture content and soil density we established 5 dry access tubes. We present results of 3D-hydrological model of observed local water mass changes together with gravity observations with SG.

  12. A theoretical consideration on uranium isotope effects observed in chemical uranium-235 enrichment processes

    International Nuclear Information System (INIS)

    Theoretical consideration on the uranium isotope effects in chemical chromatographic uranium isotope enrichment processes are presented, making use of up-to-date spectroscopic, solution chemical and separation factor data. It is shown that hydration of the uranyl (UO22+) and uranous (U4+) ions has a profound effect on the reduced partition function ratios (RPFR's) of these ions and that, in accordance with experiment, the RPFR of the uranous ion is larger than that of the uranyl ion. Future prospects concerning the separation factors in chemical processes are mentioned. (orig.)

  13. Historical variation of heavy metals with respect to different chemical forms in recent sediments from Xianghai Wetlands, Northeast China

    Energy Technology Data Exchange (ETDEWEB)

    Wang, G.P.; Liu, J.S.; Tang, J. [Chinese Academy of Science, Changchun (China)

    2004-09-15

    The research aimed to determine whether pollution trends could be reconstructed from sediment records at the downstream wetlands of the Huolin River. Sediment cores, representing a range of watershed characteristics and anthropogenic impacts, were collected from two marshes at the Xianghai Wetlands in order to trace the historical variation of heavy metals, accumulation rates, and chemical forms. Cores were Pb-210- and Cs-137-dated, and these data were used to calculate sedimentation rates and sediment accumulation rates that were compared with environmental change. Ranges of dry mass accumulation rates and sedimentation rates were0.27-0.96 g/cm{sup 2}/yr and 0.27-0.90 cm/yr. After normalization to Al the anthropogenic enrichment of Cu, Zn, Cr, and Pb occurred in the upper layer of sediments and indicated that heavy metal contamination from the hydrologic inputs primarily occurred after the 1980s, a result consistent with two decades of surface coal-mining history within the upstream region of Huolin River. Sediment inputs of most heavy metals at Xianghai Wetlands began to increase around 1885 and were generally consistent with the time of the Qing Dynasty's immigration settlement. The anthropogenic inputs of Cu, Zn, Fe, Mn, Cr, and Pb have been 1.20-3.67 times greater than their natural inputs after the 1980s, which may be due to increased inputof heavy metal-rich alluvial deposits derived from surface coal-mining activities in the watershed. Sequential extraction showed that heavy metals in sediment cores were associated with the lithogenic bonding forms and least with the exchangeable fraction (except Pb). The major fraction of Pb was in the Fe-Mn oxide fraction, indicating that Pb in these sediments had greater mobility and that it might befrom anthropogenic sources.

  14. Diurnal, seasonal and long-term variations of global formaldehyde columns inferred from combined OMI and GOME-2 observations

    Science.gov (United States)

    De Smedt, I.; Stavrakou, T.; Hendrick, F.; Danckaert, T.; Vlemmix, T.; Pinardi, G.; Theys, N.; Lerot, C.; Gielen, C.; Vigouroux, C.; Hermans, C.; Fayt, C.; Veefkind, P.; Müller, J.-F.; Van Roozendael, M.

    2015-11-01

    We present the new version (v14) of the BIRA-IASB algorithm for the retrieval of formaldehyde (H2CO) columns from spaceborne UV-visible sensors. Applied to OMI measurements from Aura and to GOME-2 measurements from MetOp-A and MetOp-B, this algorithm is used to produce global distributions of H2CO representative of mid-morning and early afternoon conditions. Its main features include (1) a new iterative DOAS scheme involving three fitting intervals to better account for the O2-O2 absorption, (2) the use of earthshine radiances averaged in the equatorial Pacific as reference spectra, and (3) a destriping correction and background normalisation resolved in the across-swath position. For the air mass factor calculation, a priori vertical profiles calculated by the IMAGES chemistry transport model at 09:30 and 13:30 LT are used. Although the resulting GOME-2 and OMI H2CO vertical columns are found to be highly correlated, some systematic differences are observed. Afternoon columns are generally larger than morning ones, especially in mid-latitude regions. In contrast, over tropical rainforests, morning H2CO columns significantly exceed those observed in the afternoon. These differences are discussed in terms of the H2CO column variation between mid-morning and early afternoon, using ground-based MAX-DOAS measurements available from seven stations in Europe, China and Africa. Validation results confirm the capacity of the combined satellite measurements to resolve diurnal variations in H2CO columns. Furthermore, vertical profiles derived from MAX-DOAS measurements in the Beijing area and in Bujumbura are used for a more detailed validation exercise. In both regions, we find an agreement better than 15 % when MAX-DOAS profiles are used as a priori for the satellite retrievals. Finally, regional trends in H2CO columns are estimated for the 2004-2014 period using SCIAMACHY and GOME-2 data for morning conditions, and OMI for early afternoon conditions. Consistent features

  15. Diurnal, seasonal and long-term variations of global formaldehyde columns inferred from combined OMI and GOME-2 observations

    Directory of Open Access Journals (Sweden)

    I. De Smedt

    2015-04-01

    Full Text Available We present the new version (v14 of the BIRA-IASB algorithm for the retrieval of formaldehyde (H2CO columns from spaceborne UV-Visible sensors. Applied to OMI measurements from Aura and to GOME-2 measurements from MetOp-A and B, this algorithm is used to produce global distributions of H2CO representative of mid-morning and early afternoon conditions. Its main features include (1 a new iterative DOAS scheme involving three fitting intervals to better account for the O2-O2 absorption, (2 the use of earthshine radiances averaged in the equatorial Pacific as reference spectra, (3 a destriping correction and background normalisation resolved in the along-swath position. For the air mass factor calculation, a priori vertical profiles calculated by the IMAGES chemistry transport model at 9.30 a.m. and 13.30 p.m. are used. Although the resulting GOME-2 and OMI H2CO vertical columns are found to be highly correlated, some systematic differences are observed. Afternoon columns are generally larger than morning ones, especially in mid-latitude regions. In contrast, over tropical rainforests, morning H2CO columns significantly exceed those observed in the afternoon. These differences are discussed in terms of the H2CO column variation between mid-morning and early afternoon, using ground-based MAX-DOAS measurements available from seven stations in Europe, China and Africa. Validation results confirm the capacity of the combined satellite measurements to resolve diurnal variations in H2CO columns. Furthermore, vertical profiles derived from MAX-DOAS measurements in the Beijing area and in Bujumbura are used for a more detailed validation exercise. In both regions, we find an agreement better than 15% when MAX-DOAS profiles are used as a priori for the satellite retrievals. Finally regional trends in H2CO columns are estimated for the 2004–2014 period using SCIAMACHY and GOME-2 data for morning conditions, and OMI for early afternoon conditions. Consistent

  16. Spatial and Temporal Variation of Physico-Chemical Parameters of Sediment from Azuabie Creek of the Upper Bonny Estuary, Niger Delta

    Directory of Open Access Journals (Sweden)

    Erema R. Daka

    2013-04-01

    Full Text Available The impacts of human and industrial activities on the physico-chemical quality of sediment of Azuabie Creek in the upper Bonny Estuary of the Niger Delta, Nigeria were studied. Major waste inputs into the creek include run-off from surrounding lands, animal wastes from a major abattoir, human/domestic waste from a high density settlements along the creek and industrial effluents from Trans-Amadi industrial area, hosting a number of manufacturing and oil servicing companies. Sediment samples were collected from ten sampling stations, seven (st. 1, 2, 6, 7, 8, 9 and 10 along the main creek and three (st. 3, 4 and 5 along a creeklet that empties into the main creek. These stations were selected to reflect various points of domestic and industrial waste inputs along the creek. Particle size distribution indicated sediments were generally sandy-mud in nature with higher proportions of clay. Seasonal and spatial variations were observed in mean pH values of sediments while the oxidation-reduction potential of the sediment varied remarkably. TOC in the study area were generally above 1% across all stations during the study while mean values of THC, ranged from 210±0.01 to 10750±0.71.3 mg/kg. NO3 and 4 also varied significantly (p≤0.001. It is concluded that physicochemical variables of sediment from Azuabie Creek are influenced by pollution sources and these would affect the benthic community in the estuarine creek.

  17. Seasonal Variation, Chemical Composition, and Analgesic and Antimicrobial Activities of the Essential Oil from Leaves of Tetradenia riparia (Hochst. Codd in Southern Brazil

    Directory of Open Access Journals (Sweden)

    Gilberto Alves Ferreira

    2010-08-01

    Full Text Available The seasonal variation of the chemical composition of the essential oil from fresh leaves of Tetradenia riparia (Hochst. Codd grown in southern Brazil was analyzed by GC-MS, and the analgesic and antimicrobial activities of this oil were assayed. The yield of essential oil ranged from 0.17% to 0.26%, with the maximum amount in winter and the minimum in spring. The results obtained from principal components analysis (PCA revealed the existence of high chemical variability in the different seasons. The samples were clearly discriminated into three groups: winter, autumn, and spring-summer. Samples collected during winter contained the highest percentages of calyculone (24.70%, abietadiene (13.54%, and viridiflorol (4.20%. In autumn, the major constituents were ledol (8.74% and cis-muurolol-5-en-4-α-ol (13.78%. Samples collected in spring-summer contained the highest percentages of fenchone (12.67%, 14-hydroxy-9-epi-caryophyllene (24.36%, and α-cadinol (8.33%. Oxygenated sesquiterpenes were predominant in all the samples analyzed. The observed chemovariation might be environmentally determined by a seasonal influence. The essential oil, when given orally at a dose of 200 mg/kg, exhibited good analgesic activity on acetic acid-induced writhing in mice, inhibiting the constrictions by 38.94% to 46.13%, and this effect was not affected by seasonal variation. The antimicrobial activity of the essential oil against the bacterial strains: Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis, Escherichia coli, Salmonella enterica, Pseudomonas aeruginosa, Klebsiella pneumonia, Proteus mirabilis, Morganella morganii, and Enterobacter cloacae, and the pathogenic fungus Candida albicans was assessed by the disc diffusion method and determination of the minimum inhibitory concentration. The results obtained, followed by measurement of the minimum inhibitory concentration (MIC, indicated that S. aureus, B. subtilis, and Candida albicans were the

  18. Variations of water vapor and cloud top altitude in the Venus' mesosphere from SPICAV/VEx observations

    Science.gov (United States)

    Fedorova, A.; Marcq, E.; Luginin, M.; Korablev, O.; Bertaux, J.-L.; Montmessin, F.

    2016-09-01

    SPICAV VIS-IR spectrometer on-board the Venus Express mission measured the H2O abundance above Venus' clouds in the 1.38 μm band, and provided an estimation of the cloud top altitude based on CO2 bands in the range of 1.4-1.6 μm. The H2O content and the cloud top altitude have been retrieved for the complete Venus Express dataset from 2006 to 2014 taking into account multiple scattering in the cloudy atmosphere. The cloud top altitude, corresponding to unit nadir aerosol optical depth at 1.48 μm, varies from 68 to 73 km at latitudes from 40ºS to 40ºN with an average of 70.2 ± 0.8 km assuming the aerosol scale height of 4 km. In high northern latitudes, the cloud top decreases to 62-68 km. The altitude of formation of water lines ranges from 59 to 66 km. The H2O mixing ratio at low latitudes (20ºS-20ºN) is equal to 6.1 ± 1.2 ppm with variations from 4 to 11 ppm and the effective altitude of 61.9 ± 0.5 km. Between 30º and 50º of latitude in both hemispheres, a local minimum was observed with a value of 5.4 ± 1 ppm corresponding to the effective altitude of 62.1 ± 0.6 km and variations from 3 to 8 ppm. At high latitudes in both hemispheres, the water content varies from 4 to 12 ppm with an average of 7.2 ± 1.4 ppm which corresponds to 60.6 ± 0.5 km. Observed variations of water vapor within a factor of 2-3 on the short timescale appreciably exceed individual measurement errors and could be explained as a real variation of the mixing ratio or/and possible variations of the cloud opacity within the clouds. The maximum of water at lower latitudes supports a possible convection and injection of water from lower atmospheric layers. The vertical gradient of water vapor inside the clouds explains well the increase of water near the poles correlating with the decrease of the cloud top altitude and the H2O effective altitude. On the contrary, the depletion of water in middle latitudes does not correlate with the H2O effective altitude and cannot be completely

  19. Asian couples in negotiation: a mixed-method observational study of cultural variations across five Asian regions.

    Science.gov (United States)

    Lee, Wai-Yung; Nakamura, Shin-Ichi; Chung, Moon Ja; Chun, Young Ju; Fu, Meng; Liang, Shu-Chuan; Liu, Cui-Lian

    2013-09-01

    The purpose of this study was to explore variations in how contemporary couples from five different Asian regions negotiate disagreements. Video recordings of 50 couples (10 each from Japan, Korea, Mainland China, Taiwan, and Hong Kong) discussing unresolved disagreements provided raw data for quantitative and qualitative analyses. First, teams of coders from each region used a common protocol to make quantitative ratings of content themes and interaction patterns for couples from their own region. An interregional panel of investigators then performed in-depth qualitative reviews for half of these cases, noting cultural differences not only in observed patterns of couple behavior but also in their own perceptions of these patterns. Both quantitative and qualitative analyses revealed clear regional differences on dimensions such as overt negativity, demand-withdraw interaction, and collaboration. The qualitative results also provided a richer, more nuanced view of other (e.g., gender-linked) conflict management patterns that the quantitative analyses did not capture. Inconsistencies between qualitative and quantitative data and between the qualitative observations of investigators from different regions were most pronounced for couples from Korea and Japan, whose conflict styles were subtler and less direct than those of couples from the other regions. PMID:24033245

  20. Chemical Composition and Size Distributions of Coastal Aerosols Observed on the U.S. East Coast

    Science.gov (United States)

    Xia, L.; Song, F.; Jusino-Atresino, R.; Thuman, C.; Gao, Y.

    2008-12-01

    Aerosol input is an important source of certain limiting nutrients, such as iron, for phytoplankton growth in several large oceanic regions. As the efficiency of biological uptake of nutrients may depend on the aerosol properties, a better knowledge of aerosol properties is critically important. Characterizing aerosols over the coastal ocean needs special attention, because the properties of aerosols could be altered by many anthropogenic processes in this land-ocean transition zone before they are transported over the remote ocean. The goal of this experiment was to examine aerosol properties, in particular chemical composition, particle-size distributions and iron solubility, over the US Eastern Seaboard, an important boundary for the transport of continental substances from North America to the North Atlantic Ocean. Our field sampling site was located at Tuckerton (39°N, 74°W) on the southern New Jersey coast. Fourteen sets of High-Volume aerosol samples and three sets of size segregated aerosol samples by a 10-stage MOUDI impactor were collected during 2007 and 2008. The ICP-MS methodology was used to analyze aerosol samples for the concentrations of thirteen trace elements: Al, Fe, Mn, Sc, Cd, Pb, Sb, Ni, Co, Cr, Cu, Zn and V. The IC procedures were applied to determine five cations (sodium, ammonium, potassium, magnesium and calcium) and eleven anions (fluoride, acetate, propionate, formate, MSA, chloride, nitrate, succinate, malonate, sulfate and oxalate). The UV spectrometry was employed for the determination of iron solubility. Preliminary results suggest three major sources of aerosols: anthropogenic, crustal and marine. At this location, the concentrations of iron (II) ranged from 2.8 to 29ng m-3, accounting for ~20% of the total iron. The iron concentrations at this coastal site were substantially lower than those observed in Newark, an urban site in northern NJ. High concentrations of iron (II) were associated with both fine and coarse aerosol

  1. Observations of ionospheric disturbances following a 5-kt chemical explosion. I - Persistent oscillation in the lower thermosphere after shock passage

    Science.gov (United States)

    Jacobson, Abram R.; Carlos, Robert C.; Blanc, Elizabeth

    1988-10-01

    A 6-min-period oscillation persisting for an hour has been observed in the ionospheric E region following a 5-kt chemical explosion on the ground 250 km south of the measurement site. The oscillations' phase velocity in the upper atmosphere is 0.15 km/s at an azimuth 60 W.

  2. Inter-annual Variations and Trend Analyses of Precipitation and Vapor Isotopes with a Global Isotope Circulation Model and Observations

    Science.gov (United States)

    Yoshimura, K.; Oki, T.

    2006-12-01

    An atmosphere, land, sea surface, and river-coupled global isotope circulation model has been developed and it successfully reproduced spatial distribution of precipitation and vapor isotopes as well as those of "real" daily to inter-annual cycles provided by GNIP. A relationship between ENSO and simulated isotope ratio anomaly shows significant signals in DJF. They show lows in Greenland, southern USA and center of the Pacific, and highs in the northern North America, South America, and center of Asia in El Nino periods. Mostly vice versa in La Nina periods. In low latitude zones, it corresponds with the anomaly variations of precipitation amount, but in high latitudes, isotopes show original information on complex water circulation. Further investigation will be done by the presentation. Long-term trends of anomaly of precipitation isotopes are interesting, too. The observation show significant increase of precipitation isotope ratio over west Europe and the simulation agrees with it. Very simply speaking, when hydrologic cycle is enhanced, precipitation isotope will be increased, because the residence time of vapor becomes shorter. The trends in GNIP and the model is well agreed with Dirmeyer and Brubaker's (2006) finding the increase trend of recycling ratio in Northern Hemisphere. GNIP, we often regard it as "already understood", still has unknown to be tackled with.

  3. Interpopulational Variations in Sexual Chemical Signals of Iberian Wall Lizards May Allow Maximizing Signal Efficiency under Different Climatic Conditions.

    Directory of Open Access Journals (Sweden)

    José Martín

    Full Text Available Sexual signals used in intraspecific communication are expected to evolve to maximize efficacy under a given climatic condition. Thus, chemical secretions of lizards might evolve in the evolutionary time to ensure that signals are perfectly tuned to local humidity and temperature conditions affecting their volatility and therefore their persistence and transmission through the environment. We tested experimentally whether interpopulational altitudinal differences in chemical composition of femoral gland secretions of male Iberian wall lizards (Podarcis hispanicus have evolved to maximize efficacy of chemical signals in different environmental conditions. Chemical analyses first showed that the characteristics of chemical signals of male lizards differed between two populations inhabiting environments with different climatic conditions in spite of the fact that these two populations are closely related genetically. We also examined experimentally whether the temporal attenuation of the chemical stimuli depended on simulated climatic conditions. Thus, we used tongue-flick essays to test whether female lizards were able to detect male scent marks maintained under different conditions of temperature and humidity by chemosensory cues alone. Chemosensory tests showed that chemical signals of males had a lower efficacy (i.e. detectability and persistence when temperature and dryness increase, but that these effects were more detrimental for signals of the highest elevation population, which occupies naturally colder and more humid environments. We suggest that the abiotic environment may cause a selective pressure on the form and expression of sexual chemical signals. Therefore, interpopulational differences in chemical profiles of femoral secretions of male P. hispanicus lizards may reflect adaptation to maximize the efficacy of the chemical signal in different climates.

  4. Study of the tidal variations in mesospheric temperature at low and mid latitudes from WINDII and potassium lidar observations

    Directory of Open Access Journals (Sweden)

    M. Shepherd

    2004-04-01

    Full Text Available Zonal mean daytime temperatures from the Wind Imaging Interferometer (WINDII on the Upper Atmosphere Research Satellite (UARS and nightly temperatures from a potassium (K lidar are employed in the study of the tidal variations in mesospheric temperature at low and mid latitudes in the Northern Hemisphere. The analysis is applied to observations at 89km height for winter solstice, December to February (DJF, at 55° N, and for May and November at 28° N. The WINDII results are based on observations from 1991 to 1997. The K-lidar observations for DJF at Kühlungsborn (54° N were from 1996–1999, while those for May and November at Tenerife 28° N were from 1999. To avoid possible effects from year-to-year variability in the temperatures observed, as well as differences due to instrument calibration and observation periods, the mean temperature field is removed from the respective data sets, assuming that only tidal and planetary scale perturbations remain in the temperature residuals. The latter are then binned in 0.5h periods and the individual data sets are fitted in a least-mean square sense to 12-h and 8-h harmonics, to infer semidiurnal and terdiurnal tidal parameters. Both the K-lidar and WINDII independently observed a strong semidiurnal tide in November, with amplitudes of 13K and 7.4K, respectively. Good agreement was also found in the tidal parameters derived from the two data sets for DJF and May. It was recognized that insufficient local time coverage of the two separate data sets could lead to an overestimation of the semidiurnal tidal amplitude. A combined ground-based/satellite data set with full diurnal local time coverage was created which was fitted to 24h+12h+8h harmonics and a novel method applied to account for possible differences between the daytime and nighttime means. The results still yielded a strong semidiurnal tide in November at 28° N with an amplitude of 8.8K which is twice the SD amplitude in May and DJF. The

  5. Chemical Composition, Seasonal Variation and Size distribution of Atmospheric Aerosols at an Alpine Site in Guanzhong Plain, China

    Science.gov (United States)

    Li, J.

    2015-12-01

    PM10 and size-segregated aerosol samples were collected at Mt. Hua (2065 a.s.m) in central China, and determined for carbonaceous fraction, ions and organic composition. The concentration of most chemical compositions in summer are lower than those in winter, due to decreased emissions of biomass and coal burning for house heating. High temperature and relative humidity (RH) conditions are favorable for secondary aerosol formation, resulting in higher concentrations of SO42- and NH4+ in summer. Non-dehydrated sugars are increased in summer because of the enhanced metabolism. Carbon preference index results indicate that n-alkanes at Mt. Hua are derived mostly by plant wax. Low Benzo(a)pyrene/Benzo(a)pyrene ratios indicate that mountain aerosols are more aged. Concentrations of biogenic (BSOA, the isoprene/pinene/caryophyllene oxidation products) and anthropogenic (ASOA, mainly aromatic acids) SOA positively correlated with temperature . However, a decreasing trend of BSOA concentration with an increase in RH was observed during the sampling period, although a clear trend between ASOA and RH was not found. Based on the AIM Model calculation, we found that during the sampling period an increase in RH resulted in a decrease in the aerosol acidity and thus reduced the effect of acid-catalysis on BSOA formation. Size distributions of K+ and NH4+ present as an accumulation mode, in contrast to Ca2+ and Mg2+, which are mainly existed in coarse particles. SO42- and NO3- show a bimodal pattern. Dehydrated sugars, fossil fuel derived n-alkanes and PAHs presented unimode size distribution, whereas non-dehydrated sugars and plant wax derived n-alkanes showed bimodal pattern. Most of the determined BSOA are formed in the aerosol phase and enriched in the fine mode except for cis-pinonic acid, which is formed in the gas phase and subsequently partitioned into aerosol phase and thus presents a bimodal pattern with a major peak in the coarse mode.

  6. Observing a Chemically and/or Climatically Important Volcano: Facilitating Rapid Response to an Unanticipated yet Inevitable Event

    Science.gov (United States)

    Kaye, J. A.

    2015-12-01

    A large volcanic event has the potential to influence the chemical and/or physical state of the Earth's atmosphere in a significant way. In particular, changes in the trace constituent and/or particulate composition of the stratosphere, as well as the temperature distribution of the troposphere and stratosphere can both take place (and persist over a period of time), as has been observed in several eruptions in recent years (e.g., the Mount Pinatubo eruption in 1991). Characterizing the impacts of these eruptions and predicting their impacts on the evolution of the atmosphere requires observations of gas and particle distributions over time period from as soon after eruption as possible to the longer time period over which the Earth system is affected. This characterization may make use of observation capabilities from ongoing surface-based and existing satellite-based observing systems, and can also benefit significantly from focused airborne campaigns that make use of both in situ and remote sensing instrumentation. This presentation will review the relevant surface- and space-based observing capability operated by NASA in the broader context of the global observing capabilities of the international community, and and will discuss potential approaches to airborne campaigns (platforms, sensors, systems, logistical consideration) that would provide the data most useful for both characterization and forecasting of both the chemical and climatic forcing and impacts associated with the eruption.

  7. Fine particles (PM2.5) at a CAWNET background site in Central China: Chemical compositions, seasonal variations and regional pollution events

    Science.gov (United States)

    Zhang, Fan; Cheng, Hai-rong; Wang, Zu-wu; Lv, Xiao-pu; Zhu, Zhong-min; Zhang, Gan; Wang, Xin-ming

    2014-04-01

    Fine particle (PM2.5) samples were collected at Jinsha (JSH), a regional background China Atmosphere Watch Network (CAWNET) site in Central China from March 2012 to March 2013. The mass concentrations of water-soluble inorganic ions (WSIIs), organic carbon (OC) and elemental carbon (EC) in PM2.5 were measured. The average PM2.5 mass concentration was 48.7 ± 26.9 μg m-3, exceeding the Chinese National Ambient Air Quality Standards (NAAQS) (35 μg m-3), implying that PM2.5 is a pollutant of regional concern in Central China. The average concentrations of total WSIIs, OC and EC were 26.1 ± 18.8, 7.5 ± 3.5 and 0.7 ± 0.5 μg m-3, accounting for 53.5%, 15.1% and 1.5% of the PM2.5 concentrations at JSH, respectively. Clear seasonal variations in PM2.5 and the levels of its main chemical species were observed in the following order: winter > autumn > spring > summer. Backward air trajectory analysis and potential source contribution function (PSCF) analysis implied that the areas north and northeast of JSH contributed significantly to the levels of SO42-, NO3-, NH4+ and OC, while sandstorms originating from Mongolia and traveling across Northwest China may have contributed significantly to the levels of Na+, Ca2+, and Mg2+ in PM2.5 at JSH. Two pollution events, related to regional biomass burning and haze, respectively, were recorded at JSH during the sampling campaign.

  8. Observations on the morphology and chemical analysis of medullary granules in chinchilla hair. Research letters

    Energy Technology Data Exchange (ETDEWEB)

    Keogh, H.J. (South African Inst. for Medical Research, Johannesburg); Haylett, T. (Council for Scientific and Industrial Research, Pretoria (South Africa). National Chemical Research Lab.)

    1983-02-01

    The ultrastructure of the medullary granules of white and grey chinchilla hair was investigated by scanning electron microscopy and chemical analysis in an attempt to clarify their structure and function. Atomic absorption spectroscopy and amino acid analysis showed them to be composed of melanin. The sample preparation for scanning electron microscopy is discussed. The metal content was qualitatively established by X-ray fluorescence spectrometry and quantitatively determined on a Varian Techtron model AAs atomic absorption spectrophotometer. Amino acid analysis of the granule, was carried out on a Beckman 121 amino acid analyser. Information is provided on the amino acid composition of the medullary granules as well as its metal content.

  9. Observations on the morphology and chemical analysis of medullary granules in chinchilla hair

    International Nuclear Information System (INIS)

    The ultrastructure of the medullary granules of white and grey chinchilla hair was investigated by scanning electron microscopy and chemical analysis in an attempt to clarify their structure and function. Atomic absorption spectroscopy and amino acid analysis showed them to be composed of melanin. The sample preparation for scanning electron microscopy is discussed. The metal content was qualitatively established by X-ray fluorescence spectrometry and quantitatively determined on a Varian Techtron model AAs atomic absorption spectrophotometer. Amino acid analysis of the granule, was carried out on a Beckman 121 amino acid analyser. Information is provided on the amino acid composition of the medullary granules as well as its metal content

  10. Seasonal variations of acetone in the upper troposphere-lower stratosphere of the northern midlatitudes as observed by ACE-FTS

    Science.gov (United States)

    Dufour, G.; Szopa, S.; Harrison, J. J.; Boone, C. D.; Bernath, P. F.

    2016-05-01

    This study reports on the climatological acetone distribution and seasonal variations in the upper troposphere and lower stratosphere of the northern midlatitudes, derived from observations by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) onboard SCISAT. The acetone profiles retrieved from 5 to ∼20 km cover the period from January 2004 to September 2010. The 1σ statistical fitting errors are typically ∼5-20% within the upper troposphere (UT), increasing in the lower stratosphere (LS) with decreasing acetone. The systematic errors range between 15% and 20%. The largest UT acetone mixing ratios (∼1200 ppt on average in July over Siberia) are observed in summer in the northern mid- and high latitudes. Mixing ratios are larger over continental regions than over the ocean. Comparisons with airborne measurements available in the literature point toward a possible underestimation in acetone retrieved from ACE-FTS. The largest differences occur primarily in winter and for the background values. This underestimation is attributed to the complexity of the spectral region used for the retrieval. The annual cycle of acetone for the 30-70°N midlatitude band shows a maximum during summer, reflecting the annual cycle of the primary terrestrial biogenic source of acetone. By comparison with ACE-FTS, the LMDz-INCA global climate-chemistry model systematically overestimates acetone mixing ratios lower than 400 ppt. This overestimation is thus generalized for the lower stratosphere, the Tropics and beyond 70°N for the upper troposphere. In contrast, in the upper troposphere of the 30-70°N region, where the acetone levels are the highest (>450 ppt on average), the model-observation differences are in the range of the observation uncertainty. However, in this region, the model fails to capture the annual cycle of acetone, culminating in July. A seasonal cycle can only be obtained by considering high biogenic emissions but this cycle is shifted

  11. Analysis of variations of external sources in comparison to data of magnetic observations within the territory of Armenia

    International Nuclear Information System (INIS)

    In the work amplitude-frequency characteristics of magnetic fields of the external sources acting in a role of hindrances at definition of variations of sources of the intra terrestrial nature in territory of Armenia are analyzed. For the purpose of allocation of local anomalies of the variations caused by structural and composition heterogeneities in the upper layers of the Earth as well as dynamic processes proceeding in them, the regional background of external variations and the component induced by them by means of the analysis of temporal series of solar and geomagnetic activity indexes is defined

  12. Physical and chemical structure of planet-forming disks probed by millimeter observations and modeling

    CERN Document Server

    Dutrey, Anne; Chapillon, Edwige; Gorti, Uma; Guilloteau, Stéphane; Hersant, Franck; Hogerheijde, Michiel; Hughes, Meredith; Meeus, Gwendolyn; Nomura, Hideko; Piétu, Vincent; Qi, Chunhua; Wakelam, Valentine

    2014-01-01

    Protoplanetary disks composed of dust and gas are ubiquitous around young stars and are commonly recognized as nurseries of planetary systems. Their lifetime, appearance, and structure are determined by an interplay between stellar radiation, gravity, thermal pressure, magnetic field, gas viscosity, turbulence, and rotation. Molecules and dust serve as major heating and cooling agents in disks. Dust grains dominate the disk opacities, reprocess most of the stellar radiation, and shield molecules from ionizing UV/X-ray photons. Disks also dynamically evolve by building up planetary systems which drastically change their gas and dust density structures. Over the past decade significant progress has been achieved in our understanding of disk chemical composition thanks to the upgrade or advent of new millimeter/Infrared facilities (SMA, PdBI, CARMA, Herschel, e-VLA, ALMA). Some major breakthroughs in our comprehension of the disk physics and chemistry have been done since PPV. This review will present and discus...

  13. Seasonal and interannual variations of HCN amounts in the upper troposphere and lower stratosphere observed by MIPAS

    Directory of Open Access Journals (Sweden)

    N. Glatthor

    2014-04-01

    Full Text Available A global HCN dataset covering nearly the complete period June 2002 to April 2012 has been derived from FTIR limb emission spectra measured with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS on the ENVISAT satellite. HCN is an almost unambiguous tracer of biomass burning with a tropospheric lifetime of 5–6 months and a stratospheric lifetime of about two years. We present a MIPAS HCN climatology with the main focus on biomass burning signatures in the upper troposphere and lower stratosphere. HCN observed by MIPAS in the southern tropical and subtropical upper troposphere has an annual cycle peaking in October–November during or shortly after the maximum of the southern hemispheric biomass burning season. Within 1–2 months after the burning season, a considerable portion of the enhanced HCN is transported southward to Antarctic latitudes. The fundamental period in the northern upper troposphere is also an annual cycle, which in the tropics peaks in May after the biomass burning seasons in northern tropical Africa and South Asia, and in the subtropics in July due to trapping of pollutants in the Asian monsoon anticyclone. However, caused by extensive biomass burning in Indonesia and Northern Africa together with northward transport of parts of the southern hemispheric plume, in several years HCN maxima are also found around October/November, which leads to semi-annual cycles in the northern tropics and subtropics. Because of overlap of interannually varying burning activities in different source regions, both southern and northern low-latitude maxima have considerable interannual variations. There is also a temporal shift between enhanced HCN in northern low and mid-to-high latitudes, indicating northward transport of pollutants. Due to additional biomass burning at mid and high latitudes this meridional transport pattern is not as clear as in the Southern Hemisphere. Presumably caused by ocean uptake, upper

  14. Satellite observations of thunderstorm related chemical changes in the middle atmosphere

    International Nuclear Information System (INIS)

    Complete text of publication follows. The impact of thunderstorm activity on the nighttime middle atmospheric NO2 and ozone is observed by the MIPAS infrared spectrometer onboard the ENVISAT satellite. The WWLLN lightning detection network is used to localise the intense thunderstorms. The original five-month dataset that led to the identification of a possible sprite-induced NO2 perturbation (Arnone et al., GRL, 35, L05807, 2008) is expanded to cover all existing MIPAS measurements during 2002-2008. Specific case studies are further discussed in conjunction with available sprite observations.

  15. Chemical Variation of Silicate Mineral Phases in Lunar Feldspathic Granulitic Impactites: Implications for Thermal Histories and Provenances

    Science.gov (United States)

    Fincke, E. M.; Ryder, G.

    2001-01-01

    We report on the internal variation and abundances of minor elements of silicate phases in lunar granulitic impactites to assess their thermal histories and the pre-metamorphic provenances of the minerals and the process that assembled the rocks. Additional information is contained in the original extended abstract.

  16. Short-term biological variation of clinical chemical values in dumeril's monitors (Varanus dumerili)

    DEFF Research Database (Denmark)

    Bertelsen, Mads Frost; Kjelgaard-Hansen, Mads Jens; Howell, Jennifer R.;

    2007-01-01

    Plasma biochemical values are routinely used in the medical management of ill reptiles, and for monitoring the health of clinically normal animals. Laboratory tests, including clinical biochemical values, are subject to biological and analytical variation, the magnitude of which determines the ut...

  17. Design and conduct of Caudwell Xtreme Everest: an observational cohort study of variation in human adaptation to progressive environmental hypoxia

    Directory of Open Access Journals (Sweden)

    Mythen Monty G

    2010-10-01

    Full Text Available Abstract Background The physiological responses to hypoxaemia and cellular hypoxia are poorly understood, and inter-individual differences in performance at altitude and outcome in critical illness remain unexplained. We propose a model for exploring adaptation to hypoxia in the critically ill: the study of healthy humans, progressively exposed to environmental hypobaric hypoxia (EHH. The aim of this study was to describe the spectrum of adaptive responses in humans exposed to graded EHH and identify factors (physiological and genetic associated with inter-individual variation in these responses. Methods Design Observational cohort study of progressive incremental exposure to EHH. Setting University human physiology laboratory in London, UK (75 m and 7 field laboratories in Nepal at 1300 m, 3500 m, 4250 m, 5300 m, 6400 m, 7950 m and 8400 m. Participants 198 healthy volunteers and 24 investigators trekking to Everest Base Camp (EBC (5300 m. A subgroup of 14 investigators studied at altitudes up to 8400 m on Everest. Main outcome measures Exercise capacity, exercise efficiency and economy, brain and muscle Near Infrared Spectroscopy, plasma biomarkers (including markers of inflammation, allele frequencies of known or suspected hypoxia responsive genes, spirometry, neurocognitive testing, retinal imaging, pupilometry. In nested subgroups: microcirculatory imaging, muscle biopsies with proteomic and transcriptomic tissue analysis, continuous cardiac output measurement, arterial blood gas measurement, trans-cranial Doppler, gastrointestinal tonometry, thromboelastography and ocular saccadometry. Results Of 198 healthy volunteers leaving Kathmandu, 190 reached EBC (5300 m. All 24 investigators reached EBC. The completion rate for planned testing was more than 99% in the investigator group and more than 95% in the trekkers. Unique measurements were safely performed at extreme altitude, including the highest (altitude field measurements of exercise

  18. Depth and temporal variations in water quality of the Snake River Plain aquifer in well USGS-59 near the Idaho Chemical Processing Plant at the Idaho National Engineering and Environmental Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Frederick, D.B. [Idaho INEL Oversight Program, Boise, ID (United States); Johnson, G.S. [Univ. of Idaho, Moscow, ID (United States). Dept. of Geology and Geological Engineering

    1997-03-01

    In-situ measurements of the specific conductance and temperature of ground water in the Snake River Plain aquifer were collected in observation well USGS-59 near the Idaho Chemical Processing Plant at the Idaho National Engineering and Environmental Laboratory. These parameters were monitored at various depths in the aquifer from October 1994 to August 1995. The specific conductance of ground water in well USGS-59, as measured in the borehole, ranged from about 450 to 900 {micro}S/cm at standard temperature (25 C). The pumping cycle of the production wells at the Idaho Chemical Processing Plant causes changes in borehole circulation patterns, and as a result the specific conductance of ground water at some depths in the well varies by up to 50% over a period of about 14 hours. However, these variations were not observed at all depths, or during each pumping cycle. The temperature of ground water in the well was typically between 12.8 and 13.8 C. The results of this study indicate that temporal variations in specific conductance of the ground water at this location are caused by an external stress on the aquifer--pumping of a production well approximately 4,000 feet away. These variations are believed to result from vertical stratification of water quality in the aquifer and a subsequent change in intrawell flow related to pumping. When sampling techniques that do not induce a stress on the aquifer (i.e., thief sampling) are used, knowledge of external stresses on the system at the time of sampling may aid in the interpretation of geochemical data.

  19. Depth and temporal variations in water quality of the Snake River Plain aquifer in well USGS-59 near the Idaho Chemical Processing Plant at the Idaho National Engineering and Environmental Laboratory

    International Nuclear Information System (INIS)

    In-situ measurements of the specific conductance and temperature of ground water in the Snake River Plain aquifer were collected in observation well USGS-59 near the Idaho Chemical Processing Plant at the Idaho National Engineering and Environmental Laboratory. These parameters were monitored at various depths in the aquifer from October 1994 to August 1995. The specific conductance of ground water in well USGS-59, as measured in the borehole, ranged from about 450 to 900 microS/cm at standard temperature (25 C). The pumping cycle of the production wells at the Idaho Chemical Processing Plant causes changes in borehole circulation patterns, and as a result the specific conductance of ground water at some depths in the well varies by up to 50% over a period of about 14 hours. However, these variations were not observed at all depths, or during each pumping cycle. The temperature of ground water in the well was typically between 12.8 and 13.8 C. The results of this study indicate that temporal variations in specific conductance of the ground water at this location are caused by an external stress on the aquifer--pumping of a production well approximately 4,000 feet away. These variations are believed to result from vertical stratification of water quality in the aquifer and a subsequent change in intrawell flow related to pumping. When sampling techniques that do not induce a stress on the aquifer (i.e., thief sampling) are used, knowledge of external stresses on the system at the time of sampling may aid in the interpretation of geochemical data

  20. The Influence of Synoptic Meteorology on Convective Boundary Layer Characteristics and the Observed Chemical Response During PROPHET 2000 and 2001 Summer Intensives

    Science.gov (United States)

    Lilly, M. A.; Moody, J. L.; Carroll, M.; Brown, W. O.; Cohn, S. A.

    2002-12-01

    from the south is advected toward the region when the UMBS sits on the back of surface anticyclones ahead of approaching frontal boundaries. This transport regime characteristically consists of air with high moisture content and an early morning low stratus deck giving way to hazy afternoon skies. Surface values of specific humidity throughout 2001 were nearly 4 g/kg higher under southerly flow. Solar radiation is partitioned into evaporating moisture and surface heating, which results in slower CBL growth. During PROPHET 2001 mean CBL heights were 200 meters lower under southerly flow when the site was located on the back of a surface anticyclone. This analysis quantifies the influence of variation in boundary layer characteristics on PROPHET chemical observations.

  1. Significant observations from a PWR steam generator chemical cleaning qualification test program

    International Nuclear Information System (INIS)

    A qualification test program for the chemical cleaning of the secondary side of steam generators was conducted in anticipation of a potential application at Indian Point 2 (IP-2). The sludge removal effectiveness was evaluated using a large-scale test facility and both simulated consolidated sludge samples and sludge removed from IP-2 steam generators during prior sludge lancing. The test also mocked up the weld geometries and locations for an accurate galvanic corrosion assessment. This large-scale test and other preliminary tests had the following three aims: (1) optimize and demonstrate the sludge removal effectiveness of the Electric Power Research Institute/Steam Generator Owners Group (EPRI/SGOG) generic cleaning process for the Westinghouse Model 44 steam generators, (2) determine the corrosion effects of the process on Westinghouse Model 44 steam generator materials that would be exposed to the process, and (3) identify technical issues that should be addressed prior to field implementation of the process. The qualification test program also included the evaluation of an eddy current technique that measures sludge height in the presence of copper (IP-2 sludge contains more than 30 percent copper)

  2. A novel chemically modified curcumin reduces severity of experimental periodontal disease in rats: initial observations.

    Science.gov (United States)

    Elburki, Muna S; Rossa, Carlos; Guimaraes, Morgana R; Goodenough, Mark; Lee, Hsi-Ming; Curylofo, Fabiana A; Zhang, Yu; Johnson, Francis; Golub, Lorne M

    2014-01-01

    Tetracycline-based matrix metalloproteinase- (MMP-) inhibitors are currently approved for two inflammatory diseases, periodontitis and rosacea. The current study addresses the therapeutic potential of a novel pleiotropic MMP-inhibitor not based on an antibiotic. To induce experimental periodontitis, endotoxin (LPS) was repeatedly injected into the gingiva of rats on one side of the maxilla; the contralateral (control) side received saline injections. Two groups of rats were treated by daily oral intubation with a chemically modified curcumin, CMC 2.24, for two weeks; the control groups received vehicle alone. After sacrifice, gingiva, blood, and maxilla were collected, the jaws were defleshed, and periodontal (alveolar) bone loss was quantified morphometrically and by μ-CT scan. The gingivae were pooled per experimental group, extracted, and analyzed for MMPs (gelatin zymography; western blot) and for cytokines (e.g., IL-1β; ELISA); serum and plasma samples were analyzed for cytokines and MMP-8. The LPS-induced pathologically excessive bone loss was reduced to normal levels based on either morphometric (P = 0.003) or μ-CT (P = 0.008) analysis. A similar response was seen for MMPs and cytokines in the gingiva and blood. This initial study, on a novel triketonic zinc-binding CMC, indicates potential efficacy on inflammatory mediators and alveolar bone loss in experimental periodontitis and warrants future therapeutic and pharmacokinetic investigations. PMID:25104884

  3. A Novel Chemically Modified Curcumin Reduces Severity of Experimental Periodontal Disease in Rats: Initial Observations

    Directory of Open Access Journals (Sweden)

    Muna S. Elburki

    2014-01-01

    Full Text Available Tetracycline-based matrix metalloproteinase- (MMP- inhibitors are currently approved for two inflammatory diseases, periodontitis and rosacea. The current study addresses the therapeutic potential of a novel pleiotropic MMP-inhibitor not based on an antibiotic. To induce experimental periodontitis, endotoxin (LPS was repeatedly injected into the gingiva of rats on one side of the maxilla; the contralateral (control side received saline injections. Two groups of rats were treated by daily oral intubation with a chemically modified curcumin, CMC 2.24, for two weeks; the control groups received vehicle alone. After sacrifice, gingiva, blood, and maxilla were collected, the jaws were defleshed, and periodontal (alveolar bone loss was quantified morphometrically and by μ-CT scan. The gingivae were pooled per experimental group, extracted, and analyzed for MMPs (gelatin zymography; western blot and for cytokines (e.g., IL-1β; ELISA; serum and plasma samples were analyzed for cytokines and MMP-8. The LPS-induced pathologically excessive bone loss was reduced to normal levels based on either morphometric (P=0.003 or μ-CT (P=0.008 analysis. A similar response was seen for MMPs and cytokines in the gingiva and blood. This initial study, on a novel triketonic zinc-binding CMC, indicates potential efficacy on inflammatory mediators and alveolar bone loss in experimental periodontitis and warrants future therapeutic and pharmacokinetic investigations.

  4. Observational approach to the chemical evolution of high-mass binaries

    CERN Document Server

    Pavlovski, K; Tamajo, E; Kolbas, V

    2010-01-01

    The complexity of composite spectra of close binaries makes the study of the individual stellar spectra extremely difficult. For this reason there exists very little information on the chemical composition of high-mass stars in close binaries, despite its importance for understanding the evolution of massive stars and close binary systems. A way around this problem exists: spectral disentangling allows a time-series of composite spectra to be decomposed into their individual components whilst preserving the total signal-to-noise ratio in the input spectra. Here we present the results of our ongoing project to obtain the atmospheric parameters of high-mass components in binary and multiple systems using spectral disentangling. So far, we have performed detailed abundance studies for 14 stars in eight eclipsing binary systems. Of these, V380 Cyg, V621 Per and V453 Cyg are the most informative as their primary components are evolved either close to or beyond the TAMS. Contrary to theoretical predictions of rotat...

  5. In situ observations during chemical vapor deposition of hexagonal boron nitride on polycrystalline copper

    DEFF Research Database (Denmark)

    Kidambi, Piran R.; Blume, Raoul; Kling, Jens;

    2014-01-01

    suggest that B is taken up in the Cu catalyst while N is not (by relative amounts), indicating element-specific feeding mechanisms including the bulk of the catalyst. We further show that oxygen intercalation readily occurs under as-grown h-BN during ambient air exposure, as is common in further...... processing, and that this negatively affects the stability of h-BN on the catalyst. For extended air exposure Cu oxidation is observed, and upon re-heating in vacuum an oxygen-mediated disintegration of the h-BN film via volatile boron oxides occurs. Importantly, this disintegration is catalyst mediated, i.......e., occurs at the catalyst/h-BN interface and depends on the level of oxygen fed to this interface. In turn, however, deliberate feeding of oxygen during h-BN deposition can positively affect control over film morphology. We discuss the implications of these observations in the context of corrosion...

  6. P-MaNGA Galaxies: Emission Lines Properties - Gas Ionisation and Chemical Abundances from Prototype Observations

    CERN Document Server

    Belfiore, F; Bundy, K; Thomas, D; Maraston, C; Wilkinson, D; Sánchez, S F; Bershady, M; Blanc, G A; Bothwell, M; Cales, S L; Coccato, L; Drory, N; Emsellem, E; Fu, H; Gelfand, J; Law, D; Masters, K; Parejko, J; Tremonti, C; Wake, D; Weijmans, A; Yan, R; Xiao, T; Zhang, K; Zheng, T; Bizyaev, D; Kinemuchi, K; Oravetz, D; Simmons, A

    2014-01-01

    MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is a SDSS-IV survey that will obtain spatially resolved spectroscopy from 3600 \\AA\\ to 10300 \\AA\\ for a representative sample of over 10000 nearby galaxies. In this paper we present the analysis of nebular emission line properties using observations of 14 galaxies obtained with P-MaNGA, a prototype of the MaNGA instrument. By using spatially resolved diagnostic diagrams we find extended star formation in galaxies that are centrally dominated by Seyfert/LINER-like emission, illustrating that galaxy characterisations based on single fibre spectra are necessarily incomplete. We observe extended (up to $\\rm 1 R_{e}$) LINER-like emission in the central regions of three galaxies. We make use of the $\\rm EW(H \\alpha)$ to argue that the observed emission is consistent with ionisation from hot evolved stars. Using stellar population indices we conclude that galactic regions which are ionised by a Seyfert/LINER-like radiation field are also devoid of recent st...

  7. Variation of chemical composition of high strength low alloy steels with different groove sizes in multi-pass conventional and pulsed current gas metal arc weld depositions

    OpenAIRE

    K. Devakumaran; M.R. Ananthapadmanaban; P. K. Ghosh

    2015-01-01

    25 mm thick micro-alloyed HSLA steel plate is welded by multi-pass GMAW and P-GMAW processes using conventional V-groove and suitably designed narrow gap with 20 mm (NG-20) and 13 mm (NG-13) groove openings. The variation of weld metal chemistry in the multi pass GMA and P-GMA weld depositions are studied by spark emission spectroscopy. It is observed that the narrow groove GMA weld joint shows significant variation of weld metal chemistry compared to the conventional V-groove GMA weld joint ...

  8. Clarification of possible ordered distributions of trivalent cations in layered double hydroxides and an explanation for the observed variation in the lower solid-solution limit

    OpenAIRE

    Richardson, IG

    2013-01-01

    The sequence of hexagonal ordered distributions of trivalent cations that are possible in the octahedral layer of layered double hydroxides is clarified, including the link between the composition and the supercell a parameter. A plausible explanation is provided for the observed variation in the lower solid-solution limit.

  9. Identification and observability problems of the induction motor for sensor-less industrial speed variation; Problemes d'identification et d'observabilite du moteur a induction pour la variation de vitesse industrielle sans capteur

    Energy Technology Data Exchange (ETDEWEB)

    Malrait, F.

    2001-02-15

    In order to improve the efficiency of a speed variator or to make autonomous the control of induction motors without mechanical sensor, the speed variator must integrate with a good precision the parameters of the motor to which it is connected. In this work, an identification phase when the motor is off is proposed. This raises the problem of the modeling of the induction motor and of the power stage (saturation model, voltage drop in the power stage components) in an unusual operation zone for a speed variator. The knowledge of the off-line electrical parameters is thus not sufficient. During normal operation, the thermal drift of resistors leads to a parametric error which can create blocking problems in the low sped domain or which can significantly lower the efficiency. The low-speed zone has been analyzed. This zone contains some intrinsic properties of the induction motor: instability, non-observability (first order). The synthesis of an observer of the induction motor is proposed which is based on the linearization of the system around a trajectory. A construction method has been developed to generate a non-singular observer for a system changing with time and having observability singularities. This result comes from this study on systems having controllability singularities for linear systems with time-variable coefficients. An exogenous loop is explicitly proposed which allows to transform the original system into integrator chains without singularities. (J.S.)

  10. Springtime daily variations in lower-tropospheric ozone over east Asia: the role of cyclonic activity and pollution as observed from space with IASI

    OpenAIRE

    G. Dufour; M. Eremenko; Cuesta, J.; C. Doche; G. Foret; M. Beekmann; A. Cheiney; Wang, Y.; Z. Cai; Liu, Y; Takigawa, M.; Y. Kanaya; J.-M. Flaud

    2015-01-01

    We use satellite observations from IASI (Infrared Atmospheric Sounding Interferometer) on board the MetOp-A satellite to evaluate the springtime daily variations in lower-tropospheric ozone over east Asia. The availability of semi-independent columns of ozone from the surface up to 12 km simultaneously with CO columns provides a powerful observational data set to diagnose the processes controlling tropospheric ozone enhancement on synoptic scales. By combining IASI observati...

  11. The use of microbial and chemical analyses to characterize the variations in fouling profile of seawater reverse osmosis (SWRO) membrane

    KAUST Repository

    Manes, Carmem Lara De O

    2013-01-01

    Biofouling of reverse osmosis (RO) membranes is one of the most common problems in desalinations plants reducing the efficiency of the water production process. The characterization of bacterial community composition from fouling layers as well as detailed analysis of surrounding chemical environment might reveal process specific bacterial groups/species that are involved in RO biofouling. In this study, advanced organics analytic methods (elemental analysis, FTIR, and ICP-OES) were combined with high-throughput 16S rRNA (pyro) sequencing to assess in parallel, the chemical properties and the active microbial community composition of SWRO membranes from a pilot desalination plant (MFT, Tarragona) in February 2011 and July 2011. Prefiltered ultrafiltration. waters fed SWRO membranes during third and fifth month of operation, respectively. SWRO samples were taken from three modules at different positions (first, fourth, and sixth) in order to investigate the spatial changes in fouling layers\\' chemical and microbiological composition. The overall assessment of chemical parameters revealed that fouling layers were mainly composed by bio and organic material (proteins and lipids). Ca and Fe were found to be the most abundant elements having an increasing concentration gradient according to the module position. Bacterial community composition of SWRO membranes is mostly represented by the Gammaproteobacteria class with interesting differences in genera/species spatial and temporal distribution. This preliminary result suggests that pretreatments and/or operational conditions might have selected different bacterial groups more adapted to colonize SWRO membranes. © 2013 Desalination Publications.

  12. Optical-chemical-microphysical relationships and closure studies for mixed carbonaceous aerosols observed at Jeju Island; 3-laser photoacoustic spectrometer, particle sizing, and filter analysis

    Directory of Open Access Journals (Sweden)

    B. A. Flowers

    2010-11-01

    Full Text Available Transport of aerosols in pollution plumes from the mainland Asian continent was observed in situ at Jeju, South Korea during the Cheju Asian Brown Cloud Plume-Asian Monsoon Experiment (CAPMEX field campaign throughout August and September 2008 using a 3-laser photoacoustic spectrometer (PASS-3, chemical filter analysis, and size distributions. The PASS-3 directly measures the effects of morphology (e.g. coatings on light absorption that traditional filter-based instruments are unable to address. Transport of mixed sulfate, carbonaceous, and nitrate aerosols from various Asian pollution plumes to Jeju accounted for 74% of the deployment days, showing large variations in their measured chemical and optical properties. Analysis of eight distinct episodes, spanning wide ranges of chemical composition, optical properties, and source regions, reveals that episodes with higher organic carbon (OC/sulfate (SO42− and nitrate (NO3/SO42− composition ratios exhibit lower single scatter albedo at shorter wavelengths (ω405. We infer complex refractive indices (n–ik as a function of wavelength for the high, intermediate, and low OC/SO42− pollution episodes by using the observed particle size distributions and the measured optical properties. The smallest mean particle diameter corresponds to the high OC/SO42− aerosol episode. The imaginary part of the refractive index (k is greater for the high OC/SO42− episode at all wavelengths. A distinct, sharp increase in k at short wavelength implies enhanced light absorption by OC, which accounts for 50% of the light absorption at 405 nm, in the high OC/SO42− episode. Idealized analysis indicates increased absorption at 781 nm by factors greater than 3 relative to denuded black carbon in the laboratory. We hypothesize

  13. Seasonal variations in planktonic foraminiferal flux and the chemical properties of their shells in the southern South China Sea

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Results from sediment trap experiments conducted in the southern South China Sea from May 2004 to March 2006 revealed significant monsoon-induced seasonal variations in flux and shell geochemistry of planktonic foraminifera. The total and species-specific fluxes showed bimodal pattern, such as those of Globigerinoides ruber, Globigerinoides sacculifer, Neoglobo-quadrina dutertrei, Globigerinita glutinata, and Globigerina bulloides. Their high values occurred in the prevailing periods of the northeast and southwest monsoons, and the low ones appeared between the monsoons. Pulleniatina obliquiloculata had high flux rates mainly during northeast monsoon, with exceptional appearance in August 2004. These fluxes changed largely in accord with those of total particle matter and organic carbon, following chlorophyll concentration and wind force. It is inferred that the biogenic particle fluxes are controlled essentially by primary productivity under the influence of East Asian monsoon in the southern SCS. Shell stable oxygen isotope and Mg/Ca data correspond with seasonal variation of sea surface temperature. Shell δ18O values are affected primarily by sea water temperature, and the δ18O changes of different-depth dwelling species indicate upper sea water temperature gradient. Besides, the low carbon isotope values occurred in the periods of East Asian monsoon in general, whereas the high ones between the monsoons. The pattern is in contrary to chlorophyll concentration change, which indicates that the variation of the carbon isotope could probably reflect the change of sea surface productivity.

  14. Herschel/HIFI Observations of Extra-Ordinary Sources: The physical and chemical structure of the Orion Bar

    Science.gov (United States)

    Nagy, Zsofia; Ossenkopf, Volker; van der Tak, Floris; Choi, Yunhee; Bergin, Edwin; Gerin, Maryvonne; Joblin, Christine; Röllig, Markus; Simon, Robert; Stutzki, Jürgen

    2015-08-01

    Young massive stars have a strong impact on their environment, including feedback due to their Far Ultraviolet (FUV) radiation. The penetration of FUV radiation into the interstellar medium affects the physical and chemical structure of high-mass star forming regions. Photon-Dominated Regions (PDRs) are interfaces between fully ionized and cold molecular material. Spectral line observations at sub-mm and far-infrared wavelengths provide information on the physics and chemistry of PDRs, and therefore help us to understand the impact of young massive stars on their surrounding interstellar medium.One of the best targets to probe PDR structure and chemistry is the Orion Bar, located at a distance of about 415 pc, with a nearly edge-on geometry. We have carried out an unbiased spectral line survey with Herschel/HIFI in the 480-1250 GHz and 1410-1910 GHz frequency range. We have identified lines from about 30 molecules, including the reactive ions CH+, SH+, CF+, and OH+ (Nagy et al., 2013; Van der Tak and Nagy et al., 2013), the high-J ladder of CO isotopes, and grain chemistry tracers such as H2CO.We interpret the molecular line emission observed in the HIFI range using detailed non-LTE and PDR models in order to probe the structure and chemistry of the Orion Bar. We present an overview of the HIFI line survey observations and their interpretation using radiative transfer and chemical models.

  15. Chemical differentiation on one-plate planets: Predictions and geologic observations for Venus

    Science.gov (United States)

    Head, James W., III; Parmentier, E. M.; Hess, P. C.

    1992-01-01

    Recent studies have examined the partial melting of planetary interiors on one-plate planets and the implications for the formation and evolution of basaltic crust and the complementary residual mantle layer. In contrast to the Earth, where the crust and residual layer move laterally and are returned to the interior following subduction, one-plate planets such as Venus are characterized by vertical accretion of the crust and residual layer. The residual mantle layer is depleted and compositionally buoyant, being less dense than undepleted mantle due to its reduced Fe/Mg and dense Al-bearing minerals; its melting temperature is also increased. As the crust and depleted mantle layer grow vertically during the thermal evolution of the planet, several stages develop. As a step in the investigation and testing of these theoretical treatments of crustal development on Venus, we investigate the predictions deriving from two of these stages (a stable thick crust and depleted layer, and a thick unstable depleted layer) and compare these to geologic and geophysical observations, speculating on how these might be interpreted in the context of the vertical crustal accretion models. In each case, we conclude with an outline of further tests and observations of these models.

  16. CSO and CARMA Observations of L1157. II. Chemical Complexity in the Shocked Outflow

    CERN Document Server

    Burkhardt, Andrew M; Corby, Joanna F; Carroll, P Brandon; Shingledecker, Christopher N; Loomis, Ryan A; Booth, Shawn Thomas; Blake, Geoffrey A; Herbst, Eric; Remijan, Anthony J; McGuire, Brett A

    2016-01-01

    L1157, a molecular dark cloud with an embedded Class 0 protostar possessing a bipolar outflow, is an excellent source for studying shock chemistry, including grain-surface chemistry prior to shocks, and post-shock, gas-phase processing. The L1157-B1 and B2 positions experienced shocks at an estimated ~2000 and 4000 years ago, respectively. Prior to these shock events, temperatures were too low for most complex organic molecules to undergo thermal desorption. Thus, the shocks should have liberated these molecules from the ice grain-surfaces en masse, evidenced by prior observations of SiO and multiple grain mantle species commonly associated with shocks. Grain species, such as OCS, CH3OH, and HNCO, all peak at different positions relative to species that are preferably formed in higher velocity shocks or repeatedly-shocked material, such as SiO and HCN. Here, we present high spatial resolution (~3") maps of CH3OH, HNCO, HCN, and HCO+ in the southern portion of the outflow containing B1 and B2, as observed with...

  17. On the magnetic field required for driving the observed angular-velocity variations in the solar convection zone

    OpenAIRE

    Antia, H. M.; Chitre, S. M.; Gough, D. O.

    2012-01-01

    A putative temporally varying circulation-free magnetic-field configuration is inferred in an equatorial segment of the solar convection zone from the helioseismologically inferred angular-velocity variation, assuming that the predominant dynamics is angular acceleration produced by the azimuthal Maxwell stress exerted by a field whose surface values are consistent with photospheric line-of-sight measurements.

  18. On the magnetic field required for driving the observed angular-velocity variations in the solar convection zone

    Science.gov (United States)

    Antia, H. M.; Chitre, S. M.; Gough, D. O.

    2013-01-01

    A putative temporally varying circulation-free magnetic-field configuration is inferred in an equatorial segment of the solar convection zone from the helioseismologically inferred angular-velocity variation, assuming that the predominant dynamics is an angular acceleration produced by the azimuthal Maxwell stress exerted by a field whose surface values are consistent with photospheric line-of-sight measurements.

  19. Characterizing Subcore Heterogeneity: A New Analytical Model and Technique to Observe the Spatial Variation of Transverse Dispersion

    Science.gov (United States)

    Boon, Maartje; Niu, Ben; Krevor, Sam

    2015-04-01

    Transverse dispersion, the lateral spread of chemical components in an aqueous solution caused by small heterogeneities in a rock, plays an important role in spreading, mixing and reaction during flow through porous media. Conventionally, transverse dispersion has been determined with the use of an annular core device and concentration measurements of the effluent (Blackwell, 1962; Hassinger and Von Rosenberg, 1968) or concentration measurements at probe locations along the core (Han et al, 1985; Harleman and Rumer, 1963). Both methods were designed around an analytical model of the transport equations assuming a single constant for the transverse dispersion coefficient, which is used to analyse the experimental data. We have developed a new core flood test with the aim of characterising chemical transport and dispersion directly in three dimensions to (1) produce higher precision observations of transverse dispersion than has been possible before and (2) so that the effects of rock heterogeneity on transport can also be observed and summarised using statistical descriptions allowing for a more nuanced picture of transport than allowed by description with a single transverse dispersion coefficient. The dispersion of a NaI aqueous solution injected into a Berea sandstone rock core was visualised in 3D with the use of a medical x-ray CT scanner. A device consisting out of three annular regions was used for injection. Water was injected into the centre and outer annular region and a NaI aqueous solution was injected in the middle annular region. An analytical solution to the flow and transport equations for this new inlet configuration was derived to design the tests. The Berea sandstone core was 20 cm long and had a diameter of 7.62cm. The core flood experiments were carried out for Peclet nr 0.5 and Peclet nr 2. At steady state, x-ray images were taken every 0.2 cm along the core. This resulted in a high quality 3D digital data set of the concentration distribution

  20. Experimental observation of local electrical signature of suspended graphene grown via chemical vapour deposition method

    International Nuclear Information System (INIS)

    We employ electrostatic force microscope (EFM) techniques to explore local electrical properties of suspended graphene on Cu foil, SiO2/Si and PET substrate. By using electrical modulation of amplitude in a tapping mode atomic force microscope tip, we can obtain distinguished electrostatic force amplitude mapping of graphene on various substrates. In particular, at nano-valley domains on Cu and a SiO2/Si surface, relatively weaker electrostatic attractive interaction is observed than at nano-peak domains. In SiO2/Si, we find that electrostatic force distribution of graphene still follows the substrate surface morphology. Furthermore, employing EFM to graphene on a PET system can be suggested as a facile tool to investigate electrical performance of graphene. (paper)

  1. Complex, dynamic combination of physical, chemical and nutritional variables controls spatio-temporal variation of sandy beach community structure.

    Directory of Open Access Journals (Sweden)

    Kelly Ortega Cisneros

    Full Text Available Sandy beach ecological theory states that physical features of the beach control macrobenthic community structure on all but the most dissipative beaches. However, few studies have simultaneously evaluated the relative importance of physical, chemical and biological factors as potential explanatory variables for meso-scale spatio-temporal patterns of intertidal community structure in these systems. Here, we investigate macroinfaunal community structure of a micro-tidal sandy beach that is located on an oligotrophic subtropical coast and is influenced by seasonal estuarine input. We repeatedly sampled biological and environmental variables at a series of beach transects arranged at increasing distances from the estuary mouth. Sampling took place over a period of five months, corresponding with the transition between the dry and wet season. This allowed assessment of biological-physical relationships across chemical and nutritional gradients associated with a range of estuarine inputs. Physical, chemical, and biological response variables, as well as measures of community structure, showed significant spatio-temporal patterns. In general, bivariate relationships between biological and environmental variables were rare and weak. However, multivariate correlation approaches identified a variety of environmental variables (i.e., sampling session, the C∶N ratio of particulate organic matter, dissolved inorganic nutrient concentrations, various size fractions of photopigment concentrations, salinity and, to a lesser extent, beach width and sediment kurtosis that either alone or combined provided significant explanatory power for spatio-temporal patterns of macroinfaunal community structure. Overall, these results showed that the macrobenthic community on Mtunzini Beach was not structured primarily by physical factors, but instead by a complex and dynamic blend of nutritional, chemical and physical drivers. This emphasises the need to recognise ocean

  2. Stratospheric O3 changes during 2001–2010: the small role of solar flux variations in a chemical transport model

    OpenAIRE

    S. S. Dhomse; Chipperfield, M. P.; Feng, W.; Ball, W. T.; Unruh, Y. C.; Haigh, J. D.; N. A. Krivova; Solanki, S. K.; A. K. Smith

    2013-01-01

    Solar spectral fluxes (or irradiance) measured by the SOlar Radiation and Climate Experiment (SORCE) show different variability at ultraviolet (UV) wavelengths compared to other irradiance measurements and models (e.g. NRL-SSI, SATIRE-S). Some modelling studies have suggested that stratospheric/lower mesospheric O3 changes during solar cycle 23 (1996–2008) can only be reproduced if SORCE solar fluxes are used. We have used a 3-D chemical transport model (CTM), forced by mete...

  3. Observational evidence for the plausible linkage of Equatorial Electrojet (EEJ) electric field variations with the post sunset F-region electrodynamics

    Science.gov (United States)

    Sreeja, V.; Devasia, C. V.; Ravindran, Sudha; Pant, Tarun Kumar

    2009-11-01

    The paper is based on a detailed observational study of the Equatorial Spread F (ESF) events on geomagnetically quiet (Ap≤20) days of the solar maximum (2001), moderate (2004) and minimum (2006) years using the ionograms and magnetograms from the magnetic equatorial location of Trivandrum (8.5° N; 77° E; dip lat ~0.5° N) in India. The study brings out some interesting aspects of the daytime Equatorial Electrojet (EEJ) related electric field variations and the post sunset F-region electrodynamics governing the nature of seasonal characteristics of the ESF phenomena during these years. The observed results seem to indicate a plausible linkage of daytime EEJ related electric field variations with pre-reversal enhancement which in turn is related to the occurrence of ESF. These electric field variations are shown to be better represented through a parameter, termed as "E", in the context of possible coupling between the E- and F-regions of the ionosphere. The observed similarities in the gross features of the variations in the parameter "E" and the F-region vertical drift (Vz) point towards the potential usage of the EEJ related parameter "E" as an useful index for the assessment of Vz prior to the occurrence of ESF.

  4. Observational evidence for the plausible linkage of Equatorial Electrojet (EEJ electric field variations with the post sunset F-region electrodynamics

    Directory of Open Access Journals (Sweden)

    V. Sreeja

    2009-11-01

    Full Text Available The paper is based on a detailed observational study of the Equatorial Spread F (ESF events on geomagnetically quiet (Ap≤20 days of the solar maximum (2001, moderate (2004 and minimum (2006 years using the ionograms and magnetograms from the magnetic equatorial location of Trivandrum (8.5° N; 77° E; dip lat ~0.5° N in India. The study brings out some interesting aspects of the daytime Equatorial Electrojet (EEJ related electric field variations and the post sunset F-region electrodynamics governing the nature of seasonal characteristics of the ESF phenomena during these years. The observed results seem to indicate a plausible linkage of daytime EEJ related electric field variations with pre-reversal enhancement which in turn is related to the occurrence of ESF. These electric field variations are shown to be better represented through a parameter, termed as "E", in the context of possible coupling between the E- and F-regions of the ionosphere. The observed similarities in the gross features of the variations in the parameter "E" and the F-region vertical drift (Vz point towards the potential usage of the EEJ related parameter "E" as an useful index for the assessment of Vz prior to the occurrence of ESF.

  5. A Possible Cause for Different Diurnal Variations of Warm Season Rainfall as Shown in Station Observations and TRMM 3B42 Data over the Southeastern Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    CHEN Haoming; YUAN Weihua; LI Jian; YU Rucong

    2012-01-01

    In this study,records from a 3-yr intensified observational experiment at eight stations along the hillside of Seqilashan over the southeastern Tibetan Plateau were analyzed and combined with records at 28 routine observation stations in the Chinese National Meteorological Station Network to investigate the influences of station location on the different diurnal rainfall variations between station records and Tropical Rainfall Measuring Mission (TRMM) data products.The results indicate that the diurnal variation of warm season rainfall is closely related to location of stations.The prevailing nocturnal rainfall peak in observations at routine stations can be largely attributed to the relatively lower location of the stations,which are mostly situated in valleys.The records at Seqilashan stations on hillsides revealed an evident diurnal afternoon peak of warm season rainfall,similar to that indicated by TRMM data.The different diurnal phases between valley and hillside stations are closely related to the orographically induced regional circulations caused by the complex topography over the Tibetan Plateau.The results of this study indicate that the prevailing nocturnal rainfall associated with the relatively lower location of routine observation stations can partially explain the diurnal rainfall variations between observation station records and TRMM data.

  6. Improved techniques for outgoing wave variational principle calculations of converged state-to-state transition probabilities for chemical reactions

    Science.gov (United States)

    Mielke, Steven L.; Truhlar, Donald G.; Schwenke, David W.

    1991-01-01

    Improved techniques and well-optimized basis sets are presented for application of the outgoing wave variational principle to calculate converged quantum mechanical reaction probabilities. They are illustrated with calculations for the reactions D + H2 yields HD + H with total angular momentum J = 3 and F + H2 yields HF + H with J = 0 and 3. The optimization involves the choice of distortion potential, the grid for calculating half-integrated Green's functions, the placement, width, and number of primitive distributed Gaussians, and the computationally most efficient partition between dynamically adapted and primitive basis functions. Benchmark calculations with 224-1064 channels are presented.

  7. Models of field-aligned currents needful to simulate the substorm variations of the electric field and other parameters observed by EISCAT

    Directory of Open Access Journals (Sweden)

    M. A. Volkov

    Full Text Available We have used the global numerical model of the coupled ionosphere-thermosphere-protonosphere system to simulate the electric-field, ion- and electron-temperature and -concentration variations observed by EISCAT during the substorm event of 25 March 1987. In our previous studies we adopted the model input data for field-aligned currents and precipitating electron fluxes to obtain an agreement between observed and modelled ionospheric variations. Now, we have calculated the field-aligned currents needful to simulate the substrom variations of the electric field and other parameters observed by EISCAT. The calculations of the field-aligned currents have been performed by means of numerical integration of the time-dependent continuity equation for the cold magnetospheric electrons. This equation was added to the system of the modelling equations including the equation for the electric-field potential to be solved jointly. In this case the inputs of the model are the spatial and time variations of the electric-field potential at the polar-cap boundaries and those of the cold magnetospheric electron concentration which have been adopted to obtain the agreement between the observed and modelled ionospheric variations for the substorm event of 25 March 1987. By this means it has been found that during the active phase of the substorm the current wedge is formed. It is connected with the region of the decreased cold magnetospheric electron content travelling westwards with a velocity of about 1 km s–1 at ionospheric levels.

  8. Line-imaging velocimetry for observing spatially heterogeneous mechanical and chemical responses in plastic bonded explosives during impact.

    Science.gov (United States)

    Bolme, C A; Ramos, K J

    2013-08-01

    A line-imaging velocity interferometer was implemented on a single-stage light gas gun to probe the spatial heterogeneity of mechanical response, chemical reaction, and initiation of detonation in explosives. The instrument is described in detail, and then data are presented on several shock-compressed materials to demonstrate the instrument performance on both homogeneous and heterogeneous samples. The noise floor of this diagnostic was determined to be 0.24 rad with a shot on elastically compressed sapphire. The diagnostic was then applied to two heterogeneous plastic bonded explosives: 3,3(')-diaminoazoxyfurazan (DAAF) and PBX 9501, where significant spatial velocity heterogeneity was observed during the build up to detonation. In PBX 9501, the velocity heterogeneity was consistent with the explosive grain size, however in DAAF, we observed heterogeneity on a much larger length scale than the grain size that was similar to the imaging resolution of the instrument. PMID:24007075

  9. VLBI observations of 3C273 at 22GHz and 43 GHz. I: Search for short time-scale structural variation

    OpenAIRE

    Mantovani, F.; Junor, W.; Valerio, C; McHardy, I.

    1999-01-01

    The results of VLBI observations of the quasar 3C273, obtained during a multi-frequency campaign in late 1992 in the radio, millimeter and X-ray bands are presented and discussed. The VLBI observations were made at 22 GHz with a Global Array and at 43 GHz with the Very Long Baseline Array. Hybrid maps and modelfits were made in order to look for any short time scale structural variations of the inner part of the radio jet. In 42 days 3C273 was observed 5 times at roughly 10 day intervals. The...

  10. Methane distribution in porewaters of the Eastern Siberian Shelf Sea - chemical, acoustic, and video observations

    Science.gov (United States)

    Bruchert, V.; Sawicka, J. E.; Samarkin, V.; Noormets, R.; Stockmann, G. J.; Bröder, L.; Rattray, J.; Steinbach, J.

    2015-12-01

    We present porewater methane and sulfate concentrations, and the isotope composition of carbon dioxide from 18 sites in areas of reported high methane water column concentrations on the Siberian shelf. Echosounder imaging and video imagery of the benthic environment were used to detect potential bubble emission from the sea bottom and to locate high methane emission areas. In areas where bubble flares were identified by acoustic echsounder imaging, recovered sediment cores provided evidence for slightly elevated porewater methane concentrations 10 cm below the sediment surface relative to sites without flares. Throughout the recovered sediment depth intervals porewater concentrations of methane were more than a factor 300 below the gas saturation limit at sea surface pressure. In addition, surface sediment video recordings provided no evidence for bubble emissions in the investigated methane hotspot areas although at nearby sites bubbles were detected higher in the water column. The conflicting observations of acoustic indications of rising bubbles and the absence of bubbles and methane oversaturation in any of the sediment cores during the whole SWERUS cruise suggest that advective methane seepage is a spatially limited phenomenon that is difficult to capture with routine ship-based core sampling methods in this field area. Recovery of a sediment core from one high-activity site indicated steep gradients in dissolved sulfate and methane in the first 8 cm of sediment pointing to the presence of anaerobic methane oxidation at a site with a high upward flux of methane. Based on the decrease of methane towards the sediment surface and the rates of sulfate reduction-coupled methane oxidation, most of the upward-transported methane was oxidized within the sediment. This conclusion is further supported by the stable isotope composition of dissolved carbon dioxide in porewaters and the precipitation of calcium carbonate minerals only found in sediment at this site

  11. Features of the seasonal variation of the semidiurnal, terdiurnal and 6-h components of ozone heating evaluated from Aura/MLS observations

    Directory of Open Access Journals (Sweden)

    J. Xu

    2012-02-01

    Full Text Available This paper presents the thermal forcing of the semidiurnal, terdiurnal, and 6-h components of the migrating tide induced by ozone heating in stratosphere and lower mesosphere. The heating as a function of local time is determined from the global ozone observed by the Microwave Limb Sounder on the Aura satellite. The harmonic components of the heating rates of the semidiurnal, terdiurnal and the 6-h periodicities are calculated using the Strobel/Zhu parameterized model and then decomposed into Hough modes. Seasonal variations of each harmonic component and its Hough modes are presented. For all three tidal components, the majority of the annual mean O3 heating projects onto symmetric modes. The semiannual variation is a prominent signal in almost all of the symmetric Hough modes near the stratopause. The strongest annual variation takes place in the asymmetric modes. The results also show that, during the solstice season, the maximum forcing of the diurnal and terdiurnal component occurs in the summer hemisphere while the maximum forcing of the semidiurnal and 6-h components occurs in the winter hemisphere. The global mean ozone density and the tidal components of the ozone heating rate are different between December–January and June–July. The asymmetry in the heating is primarily due to the 6.6% annual variation in the solar energy input into the Earth's atmosphere due to the annual variation of the Sun-Earth distance.

  12. Features of the seasonal variation of the semidiurnal, terdiurnal and 6-h components of ozone heating evaluated from Aura/MLS observations

    Energy Technology Data Exchange (ETDEWEB)

    Xu, J.; Jiang, G.; Yuan, W.; Gao, H. [Chinese Academy of Sciences, Beijing (China). State Key Lab. of Space Weather; Smith, A.K. [National Center for Atmospheric Research, Boulder, CO (United States). Atmospheric Chemistry Div.

    2012-07-01

    This paper presents the thermal forcing of the semidiurnal, terdiurnal, and 6-h components of the migrating tide induced by ozone heating in stratosphere and lower mesosphere. The heating as a function of local time is determined from the global ozone observed by the Microwave Limb Sounder on the Aura satellite. The harmonic components of the heating rates of the semidiurnal, terdiurnal and the 6-h periodicities are calculated using the Strobel/Zhu parameterized model and then decomposed into Hough modes. Seasonal variations of each harmonic component and its Hough modes are presented. For all three tidal components, the majority of the annual mean O{sub 3} heating projects onto symmetric modes. The semiannual variation is a prominent signal in almost all of the symmetric Hough modes near the stratopause. The strongest annual variation takes place in the asymmetric modes. The results also show that, during the solstice season, the maximum forcing of the diurnal and terdiurnal component occurs in the summer hemisphere while the maximum forcing of the semidiurnal and 6-h components occurs in the winter hemisphere. The global mean ozone density and the tidal components of the ozone heating rate are different between December-January and June-July. The asymmetry in the heating is primarily due to the 6.6% annual variation in the solar energy input into the Earth's atmosphere due to the annual variation of the Sun-Earth distance. (orig.)

  13. Correlations between variations in solar EUV and soft X-ray irradiance and photoelectron energy spectra observed on Mars and Earth

    Science.gov (United States)

    Peterson, W. K.; Brain, D. A.; Mitchell, D. L.; Bailey, S. M.; Chamberlin, P. C.

    2013-11-01

    extreme ultraviolet (EUV; 10-120 nm) and soft X-ray (XUV; 0-10 nm) radiation are major heat sources for the Mars thermosphere as well as the primary source of ionization that creates the ionosphere. In investigations of Mars thermospheric chemistry and dynamics, solar irradiance models are used to account for variations in this radiation. Because of limited proxies, irradiance models do a poor job of tracking the significant variations in irradiance intensity in the EUV and XUV ranges over solar rotation time scales when the Mars-Sun-Earth angle is large. Recent results from Earth observations show that variations in photoelectron energy spectra are useful monitors of EUV and XUV irradiance variability. Here we investigate photoelectron energy spectra observed by the Mars Global Surveyor (MGS) Electron Reflectometer (ER) and the FAST satellite during the interval in 2005 when Earth, Mars, and the Sun were aligned. The Earth photoelectron data in selected bands correlate well with calculations based on 1 nm resolution observations above 27 nm supplemented by broadband observations and a solar model in the 0-27 nm range. At Mars, we find that instrumental and orbital limitations to the identifications of photoelectron energy spectra in MGS/ER data preclude their use as a monitor of solar EUV and XUV variability. However, observations with higher temporal and energy resolution obtained at lower altitudes on Mars might allow the separation of the solar wind and ionospheric components of electron energy spectra so that they could be used as reliable monitors of variations in solar EUV and XUV irradiance than the time shifted, Earth-based, F10.7 index currently used.

  14. Correlations Between Variations in Solar EUV and Soft X-Ray Irradiance and Photoelectron Energy Spectra Observed on Mars and Earth

    Science.gov (United States)

    Peterson, W. K.; Brain, D. A.; Mitchell, D. L.; Bailey, S. M.; Chamberlin, P. C.

    2013-01-01

    Solar extreme ultraviolet (EUV; 10-120 nm) and soft X-ray (XUV; 0-10 nm) radiation are major heat sources for the Mars thermosphere as well as the primary source of ionization that creates the ionosphere. In investigations of Mars thermospheric chemistry and dynamics, solar irradiance models are used to account for variations in this radiation. Because of limited proxies, irradiance models do a poor job of tracking the significant variations in irradiance intensity in the EUV and XUV ranges over solar rotation time scales when the Mars-Sun-Earth angle is large. Recent results from Earth observations show that variations in photoelectron energy spectra are useful monitors of EUV and XUV irradiance variability. Here we investigate photoelectron energy spectra observed by the Mars Global Surveyor (MGS) Electron Reflectometer (ER) and the FAST satellite during the interval in 2005 when Earth, Mars, and the Sun were aligned. The Earth photoelectron data in selected bands correlate well with calculations based on 1 nm resolution observations above 27 nm supplemented by broadband observations and a solar model in the 0-27 nm range. At Mars, we find that instrumental and orbital limitations to the identifications of photoelectron energy spectra in MGS/ER data preclude their use as a monitor of solar EUV and XUV variability. However, observations with higher temporal and energy resolution obtained at lower altitudes on Mars might allow the separation of the solar wind and ionospheric components of electron energy spectra so that they could be used as reliable monitors of variations in solar EUV and XUV irradiance than the time shifted, Earth-based, F(10.7) index currently used.

  15. Exploring Conceptual Frameworks of Models of Atomic Structures and Periodic Variations, Chemical Bonding, and Molecular Shape and Polarity: A Comparison of Undergraduate General Chemistry Students with High and Low Levels of Content Knowledge

    Science.gov (United States)

    Wang, Chia-Yu; Barrow, Lloyd H.

    2013-01-01

    The purpose of the study was to explore students' conceptual frameworks of models of atomic structure and periodic variations, chemical bonding, and molecular shape and polarity, and how these conceptual frameworks influence their quality of explanations and ability to shift among chemical representations. This study employed a purposeful sampling…

  16. Variation of natural 15N abundance (δ15N) in greenhouse tomato and available nitrogen in soil supplied with cow manure or chemical fertilizers

    International Nuclear Information System (INIS)

    Cow manure or chemical fertilizers applied to greenhouse-grown tomato changed N contents and natural 15N abundance (δ15N) in tomato plants and the δ15N values of available N in soil. Cow manure increased and chemical fertilizers decreased the δ15N values of tomato plants. In the early periods of tomato culture with cow manure, the δ15N values of nitrate nitrogen of soil were higher than those of whole cow manure N, and, thereafter, dropped to δ15N values between those of soil and cow manure. Application of chemical fertilizers to soil immediately raised the δ15N values of ammonium nitrogen in soil but they dropped quickly to δ15N values between those of soil and fertilizers. On the estimation of the soil-derived N, manure-derived N and fertilizer-derived N in tomato plants based on the δ15N values of sources, much caution should be paid concerning the isotopic variation caused by N sources and isotopic fractionation during N transformation in soil. (author)

  17. The impact of variations of influent loading on the efficacy of an advanced tertiary sewage treatment plant to remove endocrine disrupting chemicals.

    Science.gov (United States)

    Hamilton, Lisa A; Tremblay, Louis A; Northcott, Grant L; Boake, Michael; Lim, Richard P

    2016-08-01

    The impact of changes in influent load on the removal of endocrine disrupting chemicals (EDCs) by sewage treatment has not been fully characterised. This study assessed the efficacy of an advanced tertiary sewage treatment plant (STP) to remove EDCs during normal and peak flow events of sewage influent using trace chemical analysis of selected EDCs and four estrogenic in vitro bioassays. During the summer holiday season, influent volume increased by 68%, nutrient concentrations by at least 26% and hydraulic retention time was reduced by 40% compared with base flow conditions. Despite these pressures on the treatment system the concentrations and mass loading of estrone, 17β-estradiol, estriol, Bisphenol A, 4-t-octylphenol and technical nonylphenol were not significantly higher (p>0.05) during the peak flow conditions compared with base flow conditions. Chemical analysis and in vitro bioassays showed that the efficacy of the STP in removing EDCs was not affected by the different loadings between baseline and peak flow regimes. This study demonstrates that large flow variations within the design capacity of advanced multi-stage STPs should not reduce the removal efficacy of EDCs. PMID:27096490

  18. Kinetics of Hydrogen Radical Reactions with Toluene Including Chemical Activation Theory Employing System-Specific Quantum RRK Theory Calibrated by Variational Transition State Theory.

    Science.gov (United States)

    Bao, Junwei Lucas; Zheng, Jingjing; Truhlar, Donald G

    2016-03-01

    Pressure-dependent reactions are ubiquitous in combustion and atmospheric chemistry. We employ a new calibration procedure for quantum Rice-Ramsperger-Kassel (QRRK) unimolecular rate theory within a chemical activation mechanism to calculate the pressure-falloff effect of a radical association with an aromatic ring. The new theoretical framework is applied to the reaction of H with toluene, which is a prototypical reaction in the combustion chemistry of aromatic hydrocarbons present in most fuels. Both the hydrogen abstraction reactions and the hydrogen addition reactions are calculated. Our system-specific (SS) QRRK approach is adjusted with SS parameters to agree with multistructural canonical variational transition state theory with multidimensional tunneling (MS-CVT/SCT) at the high-pressure limit. The new method avoids the need for the usual empirical estimations of the QRRK parameters, and it eliminates the need for variational transition state theory calculations as a function of energy, although in this first application we do validate the falloff curves by comparing SS-QRRK results without tunneling to multistructural microcanonical variational transition state theory (MS-μVT) rate constants without tunneling. At low temperatures, the two approaches agree well with each other, but at high temperatures, SS-QRRK tends to overestimate falloff slightly. We also show that the variational effect is important in computing the energy-resolved rate constants. Multiple-structure anharmonicity, torsional-potential anharmonicity, and high-frequency-mode vibrational anharmonicity are all included in the rate computations, and torsional anharmonicity effects on the density of states are investigated. Branching fractions, which are both temperature- and pressure-dependent (and for which only limited data is available from experiment), are predicted as a function of pressure. PMID:26841076

  19. Spatial variation of PM 2.5 chemical species and source-apportioned mass concentrations in New York City

    Science.gov (United States)

    Ito, Kazuhiko; Xue, Nan; Thurston, George

    2004-10-01

    Particulate matter (PM) is a chemically non-specific pollutant, and may originate or be derived from different emission source types. Thus, its toxicity may well vary depending on its chemical composition. If the PM toxicity could be determined based on source types, the regulation of PM may be implemented more effectively. A large number of monitors began collecting PM less than 2.5 μm in diameter (PM2.5) mass samples for subsequent chemical speciation starting 2000-2001 in the US. The data from this chemical speciation network can be useful for source-oriented evaluations of PM health effects. However, there are several issues that need to be considered in the analysis and interpretation of these data. One major issue is a monitor's representation of regional, sub-regional, and local air pollution exposures to the population in a city or metropolitan area. Because health outcomes in time-series air pollution epidemiological studies are aggregated over a wide geographical area, regional PM pollution may have smaller errors in exposure estimates than more spatially varying local pollution. However, the relative strength of association between source-apportioned PM and health outcomes may not be interpretable as the relative causal role of the source types. To our knowledge, there has not yet been a systematic and quantitative evaluation of this issue. In this study, we attempt to evaluate this issue by analyzing newly available PM2.5 speciation data from three monitors (a few miles apart) in New York City during 2001-2002. The strongest temporal correlations across the three monitors were found for the individual PM components that are related to secondary aerosols (e.g., S, NH4). We also conducted source-apportionment of the data using absolute principal component analysis and positive matrix factorization. We identified four major source/pollution types: (1) secondary (largely regional) aerosols; (2) soil; (3) traffic-related; and (4) residual oil burning

  20. Assessing spatio-temporal variations of precipitation-use efficiency over Tibetan grasslands using MODIS and in-situ observations

    Science.gov (United States)

    Liu, Zhengjia; Huang, Mei

    2016-03-01

    Clarifying the spatial and temporal variations in precipitation-use efficiency (PUE) is helpful for advancing our knowledge of carbon and water cycles in Tibetan grassland ecosystems. Here we use an integrated remote sensing normalized difference vegetation index (NDVI) and in-situ above-ground net primary production (ANPP) measurements to establish an empirical exponential model to estimate spatial ANPP across the entire Tibetan Plateau. The spatial and temporal variations in PUE (the ratio of ANPP to mean annual precipitation (MAP)), as well as the relationships between PUE and other controls, were then investigated during the 2001-2012 study period. At a regional scale, PUE increased from west to east. PUE anomalies increased significantly (>0.1 g·m-2·mm-1/10 yr) in the southern areas of the Tibetan Plateau yet decreased (>0.02 g·m-2·mm-1/10 yr) in the northeastern areas. For alpine meadow, we obtained an obvious breaking point in trend of PUE against elevation gradients at 3600 m above the sea level, which showed a contrasting relationship. At the inter-annual scale, PUE anomalies were smaller in alpine steppe than in alpine meadow. The results show that PUE of Tibetan grasslands is generally high in dry years and low in wet years.

  1. A 3.5-Dimensional Variational Method for Doppler Radar Data Assimilation and Its Application to Phased-Array Radar Observations

    OpenAIRE

    Qin Xu; Li Wei; Wei Gu; Jiandong Gong; Qingyun Zhao

    2010-01-01

    A 3.5-dimensional variational method is developed for Doppler radar data assimilation. In this method, incremental analyses are performed in three steps to update the model state upon the background state provided by the model prediction. First, radar radial-velocity observations from three consecutive volume scans are analyzed on the model grid. The analyzed radial-velocity fields are then used in step 2 to produce incremental analyses for the vector velocity fields at two time levels betwee...

  2. Hygroscopicity and chemical composition of Antarctic sub-micrometre aerosol particles and observations of new particle formation

    Directory of Open Access Journals (Sweden)

    E. Asmi

    2010-05-01

    Full Text Available The Antarctic near-coastal sub-micrometre aerosol particle features in summer were characterised based on measured data on aerosol hygroscopicity, size distributions, volatility and chemical ion and organic carbon mass concentrations. Hysplit model was used to calculate the history of the air masses to predict the particle origin. Additional measurements of meteorological parameters were utilised. The hygroscopic properties of particles mostly resembled those of marine aerosols. The measurements took place at 130 km from the Southern Ocean, which was the most significant factor affecting the particle properties. This is explained by the lack of additional sources on the continent of Antarctica. The Southern Ocean was thus a likely source of the particles and nucleating and condensing vapours. The particles were very hygroscopic (HGF 1.75 at 90 nm and very volatile. Most of the sub-100 nm particle volume volatilised below 100 °C. Based on chemical data, particle hygroscopic and volatile properties were explained by a large fraction of non-neutralised sulphuric acid together with organic material. The hygroscopic growth factors assessed from chemical data were similar to measured. Hygroscopicity was higher in dry continental air masses compared with the moist marine air masses. This was explained by the aging of the marine organic species and lower methanesulphonic acid volume fraction together with the changes in the inorganic aerosol chemistry as the aerosol had travelled long time over the continental Antarctica. Special focus was directed in detailed examination of the observed new particle formation events. Indications of the preference of negative over positive ions in nucleation could be detected. However, in a detailed case study, the neutral particles dominated the particle formation process. Freshly nucleated particles had the smallest hygroscopic growth factors, which increased subsequent to particle aging.

  3. Use of chemical mutagen for induction of useful genetic variation in different oil seed rape (brassica napus L.) cultivars

    International Nuclear Information System (INIS)

    Pre soaked seeds for 16 hrs of oil seed Rape cvs. Tower and Wester were treated with 1-3% concentrations of ethylene methane sulphonate (EMS) for 4 hrs with the objective to generate variation in characters of importance such as, early maturity, semi dwarf stature, lodging resistance and different yield components. After post washing (4 hrs) the seeds were filter dried and planted directly in the field as M1. Selection for desirable mutants was carried out in M2 and a number of mutants with desirable traits were selected during 1990-91. The mutants were tested for stability of the selected traits in plant to progenies in M3/M4 during 1992 and 1993. The stable 17 mutants were evaluated for yield and other agronomic characters in M5, in preliminary yield trials, during 1993-94. Eleven mutants exhibited early maturity and high yield potential than parent and local commercial variety. The promising mutants will be further tested in yield trials in future for confirmation of results. (author)

  4. Vibrational microspectroscopic identification of powdered traditional medicines: Chemical micromorphology of Poria observed by infrared and Raman microspectroscopy

    Science.gov (United States)

    Chen, Jian-bo; Sun, Su-qin; Ma, Fang; Zhou, Qun

    2014-07-01

    Microscopic identification using optical microscopes is a simple and effective method to identify powdered traditional medicines made from plants, animals and fungi. Sometimes, the criteria based on physical properties of the microscopic characteristics of drug powder may be ambiguous, which makes the microscopic identification method subjective and empirical to some extent. In this research, the vibrational microspectroscopic identification method is proposed for more explicit discrimination of powdered traditional medicines. The chemical micromorphology, i.e., chemical compositions and related physical morphologies, of the drug powder can be profiled objectively and quantitatively by infrared and Raman microspectroscopy, leading to better understanding about the formation mechanisms of microscopic characteristics and more accurate identification criteria. As an example, the powder of Poria, which is one of the most used traditional Chinese medicines, is studied in this research. Three types of hyphae are classified according to their infrared spectral features in the region from 1200 to 900 cm-1. Different kinds of polysaccharides indicate that these hyphae may be in different stages of the growth. The granular and branched clumps observed by the optical microscope may be formed from the aggregation of the mature hyphae with β-D-glucan reserves. The newfound spherical particles may originate from the exuded droplets in the fresh Poria because they are both composed of α-D-glucan. The results are helpful to understand the development of the hyphae and the formation of active polysaccharides in Poria and to establish accurate microspectroscopic identification criteria.

  5. Method for Fusing Observational Data and Chemical Transport Model Simulations To Estimate Spatiotemporally Resolved Ambient Air Pollution.

    Science.gov (United States)

    Friberg, Mariel D; Zhai, Xinxin; Holmes, Heather A; Chang, Howard H; Strickland, Matthew J; Sarnat, Stefanie Ebelt; Tolbert, Paige E; Russell, Armistead G; Mulholland, James A

    2016-04-01

    Investigations of ambient air pollution health effects rely on complete and accurate spatiotemporal air pollutant estimates. Three methods are developed for fusing ambient monitor measurements and 12 km resolution chemical transport model (CMAQ) simulations to estimate daily air pollutant concentrations across Georgia. Temporal variance is determined by observations in one method, with the annual mean CMAQ field providing spatial structure. A second method involves scaling daily CMAQ simulated fields using mean observations to reduce bias. Finally, a weighted average of these results based on prediction of temporal variance provides optimized daily estimates for each 12 × 12 km grid. These methods were applied to daily metrics of 12 pollutants (CO, NO2, NOx, O3, SO2, PM10, PM2.5, and five PM2.5 components) over the state of Georgia for a seven-year period (2002-2008). Cross-validation demonstrates a wide range in optimized model performance across pollutants, with SO2 predicted most poorly due to limitations in coal combustion plume monitoring and modeling. For the other pollutants studied, 54-88% of the spatiotemporal variance (Pearson R(2) from cross-validation) was captured, with ozone and PM2.5 predicted best. The optimized fusion approach developed provides daily spatial field estimates of air pollutant concentrations and uncertainties that are consistent with observations, emissions, and meteorology. PMID:26923334

  6. Asian dust storm observed at a rural mountain site in southern China: chemical evolution and heterogeneous photochemistry

    Directory of Open Access Journals (Sweden)

    W. Nie

    2012-12-01

    Full Text Available Heterogeneous processes on dust particles are important for understanding the chemistry and radiative balance of the atmosphere. This paper investigates an intense Asian dust storm episode observed at Mount Heng (1269 m a.s.l. in southern China on 24–26 April 2009. A set of aerosol and trace gas data collected during the study was analyzed to investigate their chemical evolution and heterogeneous photochemistry as the dust traveled to southern China. Results show that the mineral dust arriving at Mt. Heng experienced significant modifications during transport, with large enrichments in secondary species (sulfate, nitrate, and ammonium compared with the dust composition collected at an upwind mountain top site (Mount Hua. A photochemical age "clock" (−Log10(NOx/NOy was employed to quantify the atmospheric processing time. The result indicates an obvious increase in the abundance of secondary water-soluble ions in dust particles with the air mass atmospheric processing time. Based on the observations, a 4-stage evolution process is proposed for carbonate-containing Asian dust, starting from fresh dust to particles coated with hydrophilic and acidic materials. Daytime-enhanced nitrite formation on the dust particles was also observed, which indicates the recent laboratory result of the TiO2 photocatalysis of NO2 as a potential source of nitrite and nitrous acid.

  7. Asian dust storm observed at a rural mountain site in Southern China: chemical evolution and heterogeneous photochemistry

    Directory of Open Access Journals (Sweden)

    W. Nie

    2012-08-01

    Full Text Available Heterogeneous processes on dust particles are important for understanding the chemistry and radiative balance of the atmosphere. This paper investigates an intense Asian dust storm episode observed at Mount Heng (1250 m a.s.l. in Southern China on 24–26 April 2009. A set of aerosol and trace gas data collected during the study was analyzed to investigate their chemical evolution and heterogeneous photochemistry as the dust traveled to Southern China. Results show that the mineral dust arriving at Mt. Heng experienced significant modifications during transport, with large enrichments in secondary species (sulfate, nitrate, and ammonium compared with the dust composition collected at an upwind mountain top site (Mount Hua. A photochemical age "clock" (−log10(NOx/NOy was employed to quantify the atmospheric processing time. The result indicates an obvious increase in the abundance of secondary water-soluble ions in dust particles with the air mass' photochemical age. Based on the observations, a 4-stage evolution process is proposed for carbonate-rich Asian dust, starting from fresh dust to particles coated with hydrophilic and acidic materials. Daytime-enhanced nitrite formation on the dust particles was also observed, which indicates the recent laboratory result of the TiO2 photocatalysis of NO2 as a potential source of nitrite and nitrous acid.

  8. Semiannual and solar activity variations of daytime plasma observed by DEMETER in the ionosphere-plasmasphere transition region

    Science.gov (United States)

    Li, L. Y.; Cao, J. B.; Yang, J. Y.; Berthelier, J. J.; Lebreton, J.-P.

    2015-12-01

    Using the plasma data of Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) satellite and the NRLMSISE-00 atmospheric model, we examined the semiannual and solar activity variations of the daytime plasma and neutral composition densities in the ionosphere-plasmasphere transition region (~670-710 km). The results demonstrate that the semiannually latitudinal variation of the daytime oxygen ions (O+) is basically controlled by that of neutral atomic oxygen (O), whereas the latitude distributions of the helium and hydrogen ions (He+ and H+) do not fully depend on the neutral atomic helium (He) and hydrogen (H). The summer enhancement of the heavy oxygen ions is consistent with the neutral O enhancement in the summer hemisphere, and the oxygen ion density has significantly the summer-dense and winter-tenuous hemispheric asymmetry with respect to the dip equator. Although the winter enhancements of the lighter He+ and H+ ions are also associated with the neutral He and H enhancements in the winter hemisphere, the high-density light ions (He+ and H+) and electrons (e-) mainly appear at the low and middle magnetic latitudes (|λ| < 50°). The equatorial accumulations of the light plasma species indicate that the light charged particles (He+, H+, and e-) are easily transported by some equatorward forces (e.g., the magnetic mirror force and centrifugal force). The frequent Coulomb collisions between the charged particles probably lead to the particle trappings at different latitudes. Moreover, the neutral composition densities also influence their ion concentrations during different solar activities. From the low-F10.7 year (2007-2008) to the high-F10.7 year (2004-2005), the daytime oxygen ions and electrons increase with the increasing neutral atomic oxygen, whereas the daytime hydrogen ions tend to decrease with the decreasing neutral atomic hydrogen. The helium ion density has no obvious solar activity variation, suggesting that the

  9. Spatial variation of chemical composition and sources of submicron aerosol in Zurich during wintertime using mobile aerosol mass spectrometer data

    Directory of Open Access Journals (Sweden)

    C. Mohr

    2011-08-01

    Full Text Available Mobile measurements of PM1 (particulate matter with an aerodynamic diameter <1 μm chemical composition using a quadrupole aerosol mass spectrometer and a multi-angle absorption photometer were performed using the PSI mobile laboratory during winter 2007/2008 and December 2008 in the metropolitan area of Zurich, Switzerland. Positive matrix factorization (PMF applied to the organic fraction of PM1 yielded 3 factors: Hydrocarbon-like organic aerosol (HOA related to traffic emissions; organic aerosol from wood burning for domestic heating purposes (WBOA; and oxygenated organic aerosol (OOA, assigned to secondary organic aerosol formed by oxidation of volatile precursors. The chemical composition of PM1 was assessed for an urban background site and various sites throughout the city. The background site is dominated by secondary inorganic and organic species (57 %, BC, HOA, and WBOA account for 15 %, 6 %, and 12 %, respectively. As for the other sites, HOA is important along major roads (varying between 7 and 14 % of PM1 for different sites within the city, average all sites 8 %, domestic wood burning makes up between 8–15 % of PM1 for different sites within the city (average all sites 10.5 %. OOA makes up the largest fraction of organic aerosol (44 % on average. A new method allows for the separation and quantification of the local fraction of PM1 emitted or rapidly formed in the city, and the fraction of PM1 originating from the urban background. The method is based on simultaneous on-road mobile and stationary background measurements and the correction of small-scale meteorological effects using the ratio of on-road sulfate to stationary sulfate. Especially during thermal inversions over the Swiss plateau, urban background concentrations contribute substantially to particulate number concentrations (between 40 and 80 % depending on meteorological conditions and

  10. Chemical characterization, the transport pathways and potential sources of PM2.5 in Shanghai: Seasonal variations

    Science.gov (United States)

    Zhao, Mengfei; Huang, Zhongsi; Qiao, Ting; Zhang, Yuankai; Xiu, Guangli; Yu, Jianzhen

    2015-05-01

    The 24-h PM2.5 samples were collected at the site of East China University of Science and Technology (ECUST) in Shanghai from 2011 to 2012, representing winter, spring, summer and autumn, respectively. And PM2.5 and its chemical components including organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), humic-like substance carbon (HULIS-C) and water-soluble ions were analyzed. The results suggested that the average PM2.5 concentrations were (70.35 ± 43.75) μg/m3, (69.76 ± 38.67) μg/m3, (51.26 ± 28.25) μg/m3 and (82.37 ± 48.70) μg/m3 in winter, spring, summer and autumn, respectively. Secondary inorganic ions (sulfate, nitrate and ammonium) were the dominant pollutants of PM2.5 in the four seasons. Total carbon (TC) was an important component explaining above 15% of PM2.5. OC/EC ratios were all above 2 ranging from 4.31 to 6.35; particularly in winter it reached the highest 6.35 which demonstrated that secondary organic carbon (SOC) should be a significant composition of PM2.5. The SOC calculated based on the OC/EC ratio method had stronger correlation with WSOC in summer and autumn (summer: R2 = 0.73 and autumn: R2 = 0.75). The HULIS-C and SOC most significantly correlated in autumn (R2 = 0.83). The data showed that PM2.5 atmospheric aerosols were more acidic in autumn and the concentrations of PM2.5 and its chemical components were much higher. Factor analysis (FA), cluster analysis of air mass back trajectories, potential source contribution function (PSCF) model and concentration weighted trajectory (CWT) model were used to investigate the transport pathways and identify potential source areas of PM2.5 in different seasons. FA identified various sources of PM2.5: secondary aerosol reactions, the aged sea salts and road dusts. The results of cluster analysis, PSCF model and CWT model demonstrated that the local sources in the Yangtze River Delta Region (YRDR) made significant contributions to PM2.5. During winter and autumn long

  11. Assessing the potential of SWVI (Soil Wetness Variation Index for hydrological risk monitoring by means of satellite microwave observations

    Directory of Open Access Journals (Sweden)

    T. Lacava

    2005-01-01

    Full Text Available In the last years satellite remote sensing applications in hydrology have considerably progressed. A new multi-temporal satellite data-analysis approach has been recently suggested in order to estimate space-time changes of geophysical parameters possibly related to the increase of environmental and hydro-geological hazards. Such an approach has been already used both for flooded area mapping (using AVHRR data and for soil wetness index estimation (using AMSU data. In this work, a preliminary sensitivity analysis of the proposed Soil Wetness Variation Index (SWVI is made in the case of low intensity meteorological events by the comparison with hydrological (precipitation data. This analysis, as a first step of a more complex work in progress, is targeted to a first evaluation of the reliability of the SWVI in describing soil response to precipitations of different duration and intensity.

  12. Present day sea level changes: observations and climatic causes; Les variations actuelles du niveau de la mer: observations et causes climatiques

    Energy Technology Data Exchange (ETDEWEB)

    Lombard, A. [Centre National d' Etudes Spatiales (CNES), Lab. d' Etudes en Geophysiques et Oceanographie Spatiale (LEGOS-Cnes), 31 - Toulouse (France)

    2007-11-15

    After a few thousand years of relative stability, sea level has risen of about 20 cm since the beginning of the 20. century. It currently rises at an average rate of about 3 mm/yr in response to global warming. About half of this rate is directly attributed to thermal expansion of sea water due to ocean warming, while the other half is mainly due to the melting of mountain glaciers and ice sheets. Satellite observations show that sea level rise is highly non-uniform. (author)

  13. The variation of organ doses with the particle size and chemical form of an inhaled radioactive aerosol

    International Nuclear Information System (INIS)

    In this report, radiation doses to organs are calculated as a function of the particle size of the inhaled radioactive material. Aerosols with an Activity Median Aerodynamic Diameter (AMAD) from 0.1 μm to 20 μm are considered and doses accumulated by various organs in periods ranging from 1 day to 70 years are given for 65 radionuclides. A computer program is used which calculates the transformations taking place in each organ per curie of inhaled nuclide from the basic radioactivity and metabolic data. The program also calculates the resulting doses both for the organ in which the transformations occur and from penetrating radiation emitted as a result of transformations in other organs. The effects of particle size and chemical form of the nuclides on the doses received by organs are discussed. Tables of doses accumulated by 10 specific organs and other organs together with effective whole body doses are given for particle sizes 0.1 μm, 1 μm and 10 μm (AMAD). (author)

  14. Variation of the water production rate of comet C/2013 US10 (Catalina) from SOHO/SWAN observations throughout its apparition

    Science.gov (United States)

    Combi, Michael; Mäkinen, Terhi; Bertaux, Jean-Loup; Quémerais, Eric; Ferron, Stéphane

    2016-04-01

    The all-sky hydrogen Lyman-alpha camera, SWAN (Solar Wind Anisotropies), on the SOlar and Heliospheric Observatory (SOHO) satellite makes observations of the hydrogen coma of comets. Most water vapor produced by comets is ultimately photodissociated into two H atoms and one O atom producing a huge atomic hydrogen coma that is routinely observed in the daily full-sky SWAN images in comets of sufficient brightness. Water production rates are calculated using our time-resolved model (Mäkinen & Combi, 2005, Icarus 177, 217), typically yielding about 1 observation every 2 days on the average. Here we describe the analysis of observations of comets observed during 2015 and 2016 of bright comet C/2013 US10 (Catalina). C/2013 US10 reached a perihelion distance of 0.82286 AU on 15.7 November 2015. The pre-perihelion leg of the apparition followed an average power law variation of 3.7 x 1029 r‑1.3 molecules s‑1, where r is the heliocentric distance in AU. This rather flat variation is not atypical of new Oort cloud comets on their first pass through the inner solar system. Support from grants NNX11AH50G from the NASA Planetary Astronomy Program and NNX13AQ66G from the NASA Planetary Mission Data Analysis Program are gratefully acknowledged, as is support from CNRS, CNES, and the Finnish Meteorological Institute (FMI).

  15. Heavy metals in estuarine surface sediments of the Hai River Basin, variation characteristics, chemical speciation and ecological risk.

    Science.gov (United States)

    Lei, Pei; Zhang, Hong; Shan, Baoqing; Lv, Shucong; Tang, Wenzhong

    2016-04-01

    The Hai River Basin (HRB) is considered to be one of the most polluted areas in China due to the high regional population density and rapid economic development. The estuaries of the HRB, which receive pollutants from terrestrial rivers, may subsequently suffer potential pollution and result in ecological risk of heavy metals. Six heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) were measured in estuarine surface sediments from 10 estuaries of the HRB to investigate their variation characteristics and ecological risks. The spatial difference of Cr, Ni, Pb, and Zn in sediments was higher than that of the rest two elements. The Yongdingxin Estuary (YDX) and Ziyaxin Estuary (ZYX) in the Northern Hai River System (NHRS) were the most severe in terms of heavy metal contamination. According to the Risk Assessment Code (RAC) classification, Cd associated with the exchangeable and carbonate fraction (the average of 21.3 %) indicated medium risk to high risk. More than 50 % of Cr, Cu, Ni, and Zn on average were associated with the residual fraction. Based on the sum of the first three fractions (exchangeable and carbonate + reducible + oxidizable), the mobility order of these heavy metals was Cd >Pb > Zn ≈ Cu > Ni > Cr. Compared to the background values of cinnamon soil, the potential ecological risk index (RI) values ranged from 25.6 to 168, with an average of 91.2, indicating a low ecological risk in estuarine sites of the HRB. Cd and Pb were the dominant contributors to the toxic-response factor (45.8 and 25.5 %, respectively). The results give insight into the different control measures pertaining to heavy metal pollution and risk for both relatively clean estuaries and urban seriously polluted areas, respectively, for the formation of protect strategies of aquatic environment in the HRB. PMID:26758307

  16. Detailed Chemical Abundances in NGC 5824: Another Metal-Poor Globular Cluster with Internal Heavy Element Abundance Variations

    CERN Document Server

    Roederer, Ian U; Bailey, John I; Spencer, Meghin; Crane, Jeffrey D; Shectman, Stephen A

    2015-01-01

    We present radial velocities, stellar parameters, and detailed abundances of 39 elements derived from high-resolution spectroscopic observations of red giant stars in the luminous, metal-poor globular cluster NGC 5824. We observe 26 stars in NGC 5824 using the Michigan/Magellan Fiber System (M2FS) and two stars using the Magellan Inamori Kyocera Echelle (MIKE) spectrograph. We derive a mean metallicity of [Fe/H]=-1.94+/-0.02 (statistical) +/-0.10 (systematic). The metallicity dispersion of this sample of stars, 0.08 dex, is in agreement with previous work and does not exceed the expected observational errors. Previous work suggested an internal metallicity spread only when fainter samples of stars were considered, so we cannot exclude the possibility of an intrinsic metallicity dispersion in NGC 5824. The M2FS spectra reveal a large internal dispersion in [Mg/Fe], 0.28 dex, which is found in a few other luminous, metal-poor clusters. [Mg/Fe] is correlated with [O/Fe] and anti-correlated with [Na/Fe] and [Al/F...

  17. Persistent Longitudinal Variations of Plasma Density and DC Electric Fields in the Low Latitude Ionosphere Observed with Probes on the C/NOFS Satellite

    Science.gov (United States)

    Pfaff, R.; Freudenreich, H.; Klenzing, J.; Rowland, D.; Liebrecht, C.; Bromund, K.; Roddy, P.

    2010-01-01

    Continuous measurements using in situ probes on consecutive orbits of the C/N0FS satellite reveal that the plasma density is persistently organized by longitude, in both day and night conditions and at all locations within the satellite orbit, defined by its perigee and apogee of 401 km and 867 km, respectively, and its inclination of 13 degrees. Typical variations are a factor of 2 or 3 compared to mean values. Furthermore, simultaneous observations of DC electric fields and their associated E x B drifts in the low latitude ionosphere also reveal that their amplitudes are also strongly organized by longitude in a similar fashion. The drift variations with longitude are particularly pronounced in the meridional component perpendicular to the magnetic field although they are also present in the zonal component as well. The longitudes of the peak meridional drift and density values are significantly out of phase with respect to each other. Time constants for the plasma accumulation at higher altitudes with respect to the vertical drift velocity must be taken into account in order to properly interpret the detailed comparisons of the phase relationship of the plasma density and plasma velocity variations. Although for a given period corresponding to that of several days, typically one longitude region dominates the structuring of the plasma density and plasma drift data, there is also evidence for variations organized about multiple longitudes at the same time. Statistical averages will be shown that suggest a tidal "wave 4" structuring is present in both the plasma drift and plasma density data. We interpret the apparent association of the modulation of the E x B drifts with longitude as well as that of the ambient plasma density as a manifestation of tidal forces at work in the low latitude upper atmosphere. The observations demonstrate how the high duty cycle of the C/NOFS observations and its unique orbit expose fundamental processes at work in the low latitude

  18. Diurnal ozone variations in the stratosphere revealed in observations from the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on board the International Space Station (ISS)

    Science.gov (United States)

    Sakazaki, Takatoshi; Fujiwara, Masatomo; Mitsuda, Chihiro; Imai, Koji; Manago, Naohiro; Naito, Yoko; Nakamura, Tetsu; Akiyoshi, Hideharu; Kinnison, Douglas; Sano, Takuki; Suzuki, Makoto; Shiotani, Masato

    2013-04-01

    Considerable uncertainties remain in the global pattern of diurnal variation in stratospheric ozone, particularly lower to middle stratospheric ozone, which is the principal contributor to total column ozone. The Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) attached to the Japanese Experiment Module (JEM) on board the International Space Station (ISS) was developed to gather high-quality global measurements of stratospheric ozone at various local times, with the aid of superconducting mixers cooled to 4K by a compact mechanical cooler. Using the SMILES dataset, as well as data from nudged chemistry-climate models (MIROC3.2-CTM and SD-WACCM), we show that the SMILES observational data have revealed the global pattern of diurnal ozone variations throughout the stratosphere. We also found that these variations can be explained by both photochemistry and dynamics. The peak-to-peak difference in the stratospheric ozone mixing ratio (total column ozone) reached 8% (1%) over the course of a day. This variation needs to be considered when merging ozone data from different satellite measurements and even from measurements made using one specific instrument at different local times.

  19. Height variation of supergranular velocity fields determined from simultaneous OSO 8 satellite and ground-based observations

    International Nuclear Information System (INIS)

    Simultaneous satellite and ground-based observations of supergranular velocities in the Sun were made using the University of Colorado UV Spectrometer on OSO 8 and the Sacramento Peak Observatory diode array instrument. We compare our observations of the steady Doppler velocities seen toward the limb in the middle chromosphere and the photosphere: the observed Si II lambda1817 and Fe I lambda5576 spectral lines differ in height of formation by about 1400 km.The striking results of these observations are that supergranular motions are able to penetrate at leas 11 density scale heights and that, in doing so, the motion increases from about 800 m s-1 in the photosphere to at least 3000 m s-1 in the middle chromosphere. Further, a distinct change appears to occur in the flow structure: whereas the horizontal component of the velocity predominates in low photosphere, suggesting strong braking of vertical momentum, the motions higher in the atmosphere are more isotropic. These observations imply that supergranular velocities should be evident in the transition region.The strong horizontal shear layers in supergranulation must produce turbulence and internal gravity waves. These smaller scale motions have bearing on chromospheric heating and nonthermal line broadening

  20. Variations of GHGs from the lower-troposphere to the UT/LS revealed by two Japanese regular aircraft observation programs

    Science.gov (United States)

    Niwa, Yosuke; Machida, Toshinobu; Sawa, Yousuke; Tsuboi, Kazuhiro; Matsueda, Hidekazu; Imasu, Ryoichi

    2014-05-01

    A Japan-centered observation network consisting of two regular aircraft programs have revealed the greenhouse gases variations from the lower-troposphere to the upper-troposphere/lower-stratosphere (UT/LS) regions. In the Comprehensive Observation Network for Trace gases by Airliner (CONTRAIL) project, in-situ continuous measurement equipment (CME) onboard commercial passenger aircraft world-widely observes CO2 profiles in vertical over tens of airports and in horizontal in the UT/LS regions. The CONTRAIL-CME has revealed three-dimensional structure of the global CO2 distribution and has exposed significant inter-hemispheric transport of CO2 through the upper-troposphere. In inverse modeling, the CME data have provided strong constraints on CO2 flux estimation especially for the Asian tropics. Automatic flask air sampling equipment (ASE) is also onboard the CONTRAIL aircraft and has been observing CO2 mixing ratios as well as those of methane, carbon monoxide, nitrous oxide and other trace species in the upper-troposphere between Japan and Australia. The observation period of the ASE has reached 20 years. In recent years, the ASE program has extended to the northern subarctic UT/LS region and has given an insight of transport mechanisms in the UT/LS by observing seasonal GHGs variations. In the other aircraft observation program by Japan Meteorological Agency, variations of GHGs have been observed by flask-sampling onboard a C-130H aircraft horizontally in the mid-troposphere over the western North Pacific as well as vertically over Minamitorishima-Island. The C-130H aircraft has persistently observed high mixing ratios of CH4 in the mid-troposphere, which seems to be originated from fossil fuel combustion throughout the year as well as from biogenic sources during summer in the Asian regions. Those above aircraft observation programs have a significant role for constraining GHGs flux estimates by filling the data gap of the existing surface measurement network

  1. Chemical composition of modern and fossil Hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation: 1. major and minor element variation

    Directory of Open Access Journals (Sweden)

    G. Brügmann

    2011-05-01

    displays the opposite variation.

    Fossil enamel from hippopotamids which lived in the saline Lake Kikorongo have a much higher MgO/Na2O ratio (∼1.11 than those from the Neogene fossils of Lake Albert (MgO/Na2O∼0.4, which was a large fresh water lake like those in the western Branch of the East African Rift System today. Similarly, the MgO/Na2O ratio in modern enamel from the White Nile River (∼0.36, which has a Precambrian catchment of dominantly granite and gneisses and passes through several saline zones, is higher than that from the Blue Nile River, whose catchment is the Neogene volcanic Ethiopian Highland (MgO/Na2O∼0.22. Thus, particularly MgO/Na2O might be a sensitive fingerprint for environments where river and lake water have suffered strong evaporation.

    Enamel formation in mammals takes place at successive mineralization fronts within a confined chamber where ion and molecule transport is controlled by the surrounding enamel organ. During the secretion and maturation phases the epithelium generates different fluid composition, which in principle, should determine the final composition of enamel apatite. This is supported by co-linear relationships between MgO, Cl and Na2O which can be interpreted as binary mixing lines. However, if maturation starts after secretion is completed the observed element distribution can only be explained by recrystallization of existing and addition of new apatite during maturation. Perhaps the initial enamel crystallites precipitating during secretion and the newly formed bioapatite crystals during maturation equilibrate with a continuously evolving fluid. During crystallization of bioapatite the enamel fluid becomes continuously depleted in MgO and Na2O, but enriched in Cl which results in the formation of MgO, and Na2O-rich, but Cl-poor bioapatite near the EDJ and MgO- and Na2O-poor, but Cl-rich bioapatite at

  2. Chemical composition of modern and fossil Hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation: 1. major and minor element variation

    Science.gov (United States)

    Brügmann, G.; Krause, J.; Brachert, T. C.; Kullmer, O.; Schrenk, F.; Ssemmanda, I.; Mertz, D. F.

    2011-05-01

    Bioapatite in mammalian teeth is readily preserved in continental sediments and represents a very important archive for reconstructions of environment and climate evolution. This project intends to provide a detailed data base of major, minor and trace element and isotope tracers for tooth apatite using a variety of microanalytical techniques. The aim is to identify specific sedimentary environments and to improve our understanding on the interaction between internal metabolic processes during tooth formation and external nutritional control and secondary alteration effects. Here, we use the electron microprobe, to determine the major and minor element contents of fossil and modern molar enamel, cement and dentin from hippopotamids. Most of the studied specimens are from different ecosystems in Eastern Africa, representing modern and fossil lakustrine (Lake Kikorongo, Lake Albert, and Lake Malawi) and modern fluvial environments of the Nile River system. Secondary alteration effects in particular FeO, MnO, SO3 and F concentrations, which are 2 to 10 times higher in fossil than in modern enamel; secondary enrichments in fossil dentin and cement are even higher. In modern and fossil enamel, along sections perpendicular to the enamel-dentin junction (EDJ) or along cervix-apex profiles, P2O5 and CaO contents and the CaO/P2O5 ratios are very constant (StdDev ~1 %). Linear regression analysis reveals very tight control of the MgO (R2∼0.6), Na2O and Cl variation (for both R2>0.84) along EDJ-outer enamel rim profiles, despite large concentration variations (40 % to 300 %) across the enamel. These minor elements show well defined distribution patterns in enamel, similar in all specimens regardless of their age and origin, as the concentration of MgO and Na2O decrease from the enamel-dentin junction (EDJ) towards the outer rim, whereas Cl displays the opposite variation. Fossil enamel from hippopotamids which lived in the saline Lake Kikorongo have a much higher MgO/Na2O

  3. Hydro-chemical Survey and Quantifying Spatial Variations of Groundwater Quality in Dwarka, Sub-city of Delhi, India

    Science.gov (United States)

    Rawat, Kishan Singh; Tripathi, Vinod Kumar

    2015-06-01

    Hydrological and geological aspect of the region play vital role for water resources utilization and development. Protection and management of groundwater resources are possible with the study of spatio-temporal water quality parameters. The study was undertaken to assess the deterioration in groundwater quality, through systematic sampling during post monsoon seasons of the year 2008 by collecting water samples from thirty bore wells located in Dwarka, sub-city of Delhi, India. The average concentrations of groundwater quality parameters namely Calcium (Ca2+), Magnesium (Mg2+), Nitrate (NO3 -), Chloride (Cl-), sulphate (SO4 2-), total hardness (TH), total dissolved solids (TDS), and electrical conductivity were 300, 178, 26.5, 301, 103, 483, 1042 mg/l and 1909 μS/cm respectively. Estimated physico-chemical parameters revealed that 7 % of the groundwater samples shown nitrate concentrations higher than safe limit prescribed by World Health Organization (WHO). Groundwater quality the in study region was poor due to come out result that NO3 - concentration exceeding the threshold value of 50 mg/l, and main cause is disposal of sewage and animal wastes to Najafgarh drain. Dominant cations are Mg2+, Ca2+ and anions are SO4 2- and Cl-. The abundance of the major ions in groundwater is in the order: Ca2+ > Mg2+ and Cl- > SO4 2- > NO3. TH have strong correlation with Ca2+ (r = 0.81), Mg2+ (r = 0.82), Cl- (r = 0.86) but poor correlation with TDS (r = 0.52). Knowledge of correlation values between water quality parameters is helpful to take decision of appropriate management strategy for controlling groundwater pollution.

  4. Inter-laboratory variation in the chemical analysis of acidic forest soil reference samples from eastern North America

    Science.gov (United States)

    Ross, Donald S.; Bailiey, Scott W; Briggs, Russell D; Curry, Johanna; Fernandez, Ivan J.; Fredriksen, Guinevere; Goodale, Christine L.; Hazlett, Paul W.; Heine, Paul R; Johnson, Chris E.; Larson, John T; Lawrence, Gregory B.; Kolka, Randy K; Ouimet, Rock; Pare, D; Richter, Daniel D.; Shirmer, Charles D; Warby, Richard A.F.

    2015-01-01

    Long-term forest soil monitoring and research often requires a comparison of laboratory data generated at different times and in different laboratories. Quantifying the uncertainty associated with these analyses is necessary to assess temporal changes in soil properties. Forest soil chemical properties, and methods to measure these properties, often differ from agronomic and horticultural soils. Soil proficiency programs do not generally include forest soil samples that are highly acidic, high in extractable Al, low in extractable Ca and often high in carbon. To determine the uncertainty associated with specific analytical methods for forest soils, we collected and distributed samples from two soil horizons (Oa and Bs) to 15 laboratories in the eastern United States and Canada. Soil properties measured included total organic carbon and nitrogen, pH and exchangeable cations. Overall, results were consistent despite some differences in methodology. We calculated the median absolute deviation (MAD) for each measurement and considered the acceptable range to be the median 6 2.5 3 MAD. Variability among laboratories was usually as low as the typical variability within a laboratory. A few areas of concern include a lack of consistency in the measurement and expression of results on a dry weight basis, relatively high variability in the C/N ratio in the Bs horizon, challenges associated with determining exchangeable cations at concentrations near the lower reporting range of some laboratories and the operationally defined nature of aluminum extractability. Recommendations include a continuation of reference forest soil exchange programs to quantify the uncertainty associated with these analyses in conjunction with ongoing efforts to review and standardize laboratory methods.

  5. Intra- and inter-observer variation in histological criteria used in age at death determination based on femoral cortical bone

    DEFF Research Database (Denmark)

    Lynnerup, N; Thomsen, J L; Frohlich, B

    1998-01-01

    been carried out dealing with the intra- and inter-observer error. Furthermore, when such studies have been completed, the statistical tools for assessing variability have not been adequate. This study presents the results of applying simple quantitative statistics on several counts of microscopic......, precluding the use of osteon fragments and Haversian canals. The observers in this study included experienced and inexperienced users of the microscopic method, yet the variability was uniformly large for all observers, suggesting fundamental problems in definition and identification of the structural......The microscopic method of age at death determination was introduced by Kerley in 1965. The method, which relies on the quantification of selected elements in cortical bone tissue, has been widely used, and several other researchers have modified or added to the method. Yet, very few studies have...

  6. Long-Term Variation of Stratospheric Aerosols Observed With Lidar from 1982 to 2014 Over Tsukuba, Japan

    Science.gov (United States)

    Sakai, Tetsu; Uchino, Osamu; Nagai, Tomohiro; Fujimoto, Toshifumi; Tabata, Isao

    2016-06-01

    The vertical distribution of stratospheric aerosols has been measured with lidars at the Meteorological Research Institute (MRI) over Tsukuba since 1982. After two major volcanic eruptions (Mt. El Chichón in 1982 and Mt. Pinatubo in 1991), stratospheric aerosol loading increased about 50-100 times compared with the background level which was observed for 1997-2000. From 2000 to 2012, a slight increase (5.3% year-1) was observed by some volcanic eruptions. This long-term lidar data have been used for assessing of impact of the stratospheric aerosols on climate and the ozone layer.

  7. Gas and dust productions of Comet 103P/Hartley 2 from millimetre observations: Interpreting rotation-induced time variations

    OpenAIRE

    Boissier, J.; Bockelée-Morvan, D.; Biver, N; Colom, P.; Crovisier, J; Moreno, R.; Zakharov, V.; Groussin, O.; Jorda, L.; Lis, D. C.

    2014-01-01

    Comet 103P/Hartley 2 made a close approach to the Earth in October 2010. It was the target of an extensive observing campaign including ground- and orbit-based observatories and was visited by the Deep Impact spacecraft in the framework of its mission extension EPOXI. We present observations of HCN and CH_3OH emission lines conducted with the IRAM Plateau de Bure interferometer on 22–23, 28 October and 4, 5 November 2010 at 1.1, 1.9 and 3.4 mm wavelengths. The thermal emission from the dust c...

  8. Work function variation of MoS2 atomic layers grown with chemical vapor deposition: The effects of thickness and the adsorption of water/oxygen molecules

    International Nuclear Information System (INIS)

    The electrical properties of two-dimensional atomic sheets exhibit remarkable dependences on layer thickness and surface chemistry. Here, we investigated the variation of the work function properties of MoS2 films prepared with chemical vapor deposition (CVD) on SiO2 substrates with the number of film layers. Wafer-scale CVD MoS2 films with 2, 4, and 12 layers were fabricated on SiO2, and their properties were evaluated by using Raman and photoluminescence spectroscopies. In accordance with our X-ray photoelectron spectroscopy results, our Kelvin probe force microscopy investigation found that the surface potential of the MoS2 films increases by ∼0.15 eV when the number of layers is increased from 2 to 12. Photoemission spectroscopy (PES) with in-situ annealing under ultra high vacuum conditions was used to directly demonstrate that this work function shift is associated with the screening effects of oxygen or water molecules adsorbed on the film surface. After annealing, it was found with PES that the surface potential decreases by ∼0.2 eV upon the removal of the adsorbed layers, which confirms that adsorbed species have a role in the variation in the work function

  9. Work function variation of MoS{sub 2} atomic layers grown with chemical vapor deposition: The effects of thickness and the adsorption of water/oxygen molecules

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Hun; Kim, Jae Hyeon; Park, Jeong Young, E-mail: peterlee@skku.edu, E-mail: jeongypark@kaist.ac.kr [Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 305–701 (Korea, Republic of); Graduate School of EEWS, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305–701 (Korea, Republic of); Lee, Jinhwan [School of Mechanical Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Hwang, C. C. [Beamline Research Division, Pohang Accelerator Laboratory (PAL), Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Lee, Changgu, E-mail: peterlee@skku.edu, E-mail: jeongypark@kaist.ac.kr [School of Mechanical Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); SKKU Advanced Institute of Nanotechnology (SAINT) and Center for Human Interface Nano Technology (HINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2015-06-22

    The electrical properties of two-dimensional atomic sheets exhibit remarkable dependences on layer thickness and surface chemistry. Here, we investigated the variation of the work function properties of MoS{sub 2} films prepared with chemical vapor deposition (CVD) on SiO{sub 2} substrates with the number of film layers. Wafer-scale CVD MoS{sub 2} films with 2, 4, and 12 layers were fabricated on SiO{sub 2}, and their properties were evaluated by using Raman and photoluminescence spectroscopies. In accordance with our X-ray photoelectron spectroscopy results, our Kelvin probe force microscopy investigation found that the surface potential of the MoS{sub 2} films increases by ∼0.15 eV when the number of layers is increased from 2 to 12. Photoemission spectroscopy (PES) with in-situ annealing under ultra high vacuum conditions was used to directly demonstrate that this work function shift is associated with the screening effects of oxygen or water molecules adsorbed on the film surface. After annealing, it was found with PES that the surface potential decreases by ∼0.2 eV upon the removal of the adsorbed layers, which confirms that adsorbed species have a role in the variation in the work function.

  10. Transit timing observations from Kepler. V. Transit timing variation candidates in the first sixteen months from polynomial models

    DEFF Research Database (Denmark)

    Ford, E.B.; Ragozzine, D.; Holman, M.J.;

    2012-01-01

    first sixteen months of Kepler observations. We present 39 strong TTV candidates based on long-term trends (2.8% of suitable data sets). We present another 136 weaker TTV candidates (9.8% of suitable data sets) based on the excess scatter of TTV measurements about a linear ephemeris. We anticipate that...

  11. Change in refractivity of the atmosphere and large variation in TEC associated with some earthquakes, observed from GPS receiver

    Science.gov (United States)

    Karia, S. P.; Pathak, K. N.

    2011-03-01

    The present study reports the analysis of GPS based TEC for our station Surat (21.16°N, 72.78°E) located at the northern crest of equatorial anomaly region in India at times close to some earthquake events (M ⩾ 5) during the year 2009 in India and its neighbouring regions. The TEC data used in the study are obtained from GPS Ionospheric Scintillation and TEC Monitoring (GISTM) system. The TEC data has been analysed corresponding to 11 earthquakes in low solar activity period and quiet geomagnetic condition. We found that, out of 11 cases of earthquakes (M > 5) there were seven cases in which enhancement in TEC occurred on earthquake day and in other four cases there was depletion in TEC on earthquake day. The variation in refractivity prior to earthquake was significant for the cases in which the epicentre lied within a distance of 600 km from the receiving station. By looking into the features on temporal enhancement and depletion of TEC a prediction was made 3-2 days prior to an earthquake (on 28 October 2009 in Bhuj - India). The paper includes a brief discussion on the method of potentially identifying an impending earthquake from ionospheric data.

  12. Spatial and temporal variations in plant Water Use Efficiency inferred from tree-ring, eddy covariance and atmospheric observations

    Science.gov (United States)

    Groenendijk, Margriet; Cox, Peter M.; Booth, Ben B. B.; Dekker, Stefan C.; Huntingford, Chris

    2016-02-01

    Plant Water Use Efficiency (WUE), which is the ratio of the uptake of carbon dioxide through photosynthesis to the loss of water through transpiration, is a very useful metric of the functioning of the land biosphere. WUE is expected to increase with atmospheric CO2, but to decline with increasing atmospheric evaporative demand - which can arise from increases in near-surface temperature or decreases in relative humidity. We have used Δ13C measurements from tree-rings, along with eddy-covariance measurements from Fluxnet sites, to estimate the sensitivities of WUE to changes in CO2 and atmospheric humidity deficit. This enables us to reconstruct fractional changes in WUE, based on changes in atmospheric climate and CO2, for the entire period of the instrumental global climate record. We estimate that overall WUE increased from 1900 to 2010 by 48 ± 22 %, which is more than double that simulated by the latest Earth System Models. This long-term trend is largely driven by increases in CO2, but significant inter-annual variability and regional differences are evident due to variations in temperature and relative humidity. There are several highly populated regions, such as Western Europe and East Asia, where the rate of increase of WUE has declined sharply in the last two decades.

  13. Seasonal variation of vertical distribution of aerosol single scattering albedo over Indian sub-continent: RAWEX aircraft observations

    Science.gov (United States)

    Suresh Babu, S.; Nair, Vijayakumar S.; Gogoi, Mukunda M.; Krishna Moorthy, K.

    2016-01-01

    To characterize the vertical distribution of aerosols and its seasonality (especially the single scattering albedo, SSA) extensive profiling of aerosol scattering and absorption coefficients have been carried out using an instrumented aircraft from seven base stations spread across the Indian mainland during winter 2012 and spring/pre-monsoon 2013 under the Regional Aerosol Warming Experiment (RAWEX). Spatial variation of the vertical profiles of the asymmetry parameter, the wavelength exponent of the absorption coefficient and the single scattering albedo, derived from the measurements, are used to infer the source characteristics of winter and pre-monsoon aerosols as well as the seasonality of free tropospheric aerosols. The relatively high value of the wavelength exponent of absorption coefficient over most of the regions indicates the contribution from biomass burning and dust aerosols up to lower free tropospheric altitudes. A clear enhancement in aerosol loading and its absorbing nature is seen at lower free troposphere levels (above the planetary boundary layer) over the entire mainland during spring/pre-monsoon season compared to winter, whereas concentration of aerosols within the boundary layer showed a decrease from winter to spring. This could have significant implications on the aerosol heating structure over the Indian region and hence the regional climate.

  14. Spatial and temporal variations in plant water-use efficiency inferred from tree-ring, eddy covariance and atmospheric observations

    Science.gov (United States)

    Dekker, Stefan C.; Groenendijk, Margriet; Booth, Ben B. B.; Huntingford, Chris; Cox, Peter M.

    2016-06-01

    Plant water-use efficiency (WUE), which is the ratio of the uptake of carbon dioxide through photosynthesis to the loss of water through transpiration, is a very useful metric of the functioning of the land biosphere. WUE is expected to increase with atmospheric CO2, but to decline with increasing atmospheric evaporative demand - which can arise from increases in near-surface temperature or decreases in relative humidity. We have used Δ13C measurements from tree rings, along with eddy covariance measurements from Fluxnet sites, to estimate the sensitivities of WUE to changes in CO2 and atmospheric humidity deficit. This enables us to reconstruct fractional changes in WUE, based on changes in atmospheric climate and CO2, for the entire period of the instrumental global climate record. We estimate that overall WUE increased from 1900 to 2010 by 48 ± 22 %, which is more than double that simulated by the latest Earth System Models. This long-term trend is largely driven by increases in CO2, but significant inter-annual variability and regional differences are evident due to variations in temperature and relative humidity. There are several highly populated regions, such as western Europe and East Asia, where the rate of increase of WUE has declined sharply in the last 2 decades. Our data-based analysis indicates increases in WUE that typically exceed those simulated by Earth System Models - implying that these models are either underestimating increases in photosynthesis or underestimating reductions in transpiration.

  15. Springtime daily variations in lower-tropospheric ozone over east Asia: the role of cyclonic activity and pollution as observed from space with IASI

    Science.gov (United States)

    Dufour, G.; Eremenko, M.; Cuesta, J.; Doche, C.; Foret, G.; Beekmann, M.; Cheiney, A.; Wang, Y.; Cai, Z.; Liu, Y.; Takigawa, M.; Kanaya, Y.; Flaud, J.-M.

    2015-09-01

    We use satellite observations from IASI (Infrared Atmospheric Sounding Interferometer) on board the MetOp-A satellite to evaluate the springtime daily variations in lower-tropospheric ozone over east Asia. The availability of semi-independent columns of ozone from the surface up to 12 km simultaneously with CO columns provides a powerful observational data set to diagnose the processes controlling tropospheric ozone enhancement on synoptic scales. By combining IASI observations with meteorological reanalyses from ERA-Interim, we develop an analysis method based only on IASI ozone and CO observations to identify the respective roles of the stratospheric source and the photochemical source in ozone distribution and variations over east Asia. The succession of low- and high-pressure systems drives the day-to-day variations in lower-tropospheric ozone. A case study analysis of one frontal system and one cut-off low system in May 2008 shows that reversible subsiding and ascending ozone transfers in the upper-troposphere-lower-stratosphere (UTLS) region, due to the tropopause perturbations occurring in the vicinity of low-pressure systems, impact free and lower-tropospheric ozone over large regions, especially north of 40° N, and largely explain the ozone enhancement observed with IASI for these latitudes. Irreversible stratosphere-troposphere exchanges of ozone-rich air masses occur more locally in the southern and southeastern flanks of the trough. The contribution to the lower-tropospheric ozone column is difficult to dissociate from the tropopause perturbations generated by weather systems. For regions south of 40° N, a significant correlation has been found between lower-tropospheric ozone and carbon monoxide (CO) observations from IASI, especially over the North China Plain (NCP). Considering carbon monoxide observations as a pollutant tracer, the O3-CO correlation indicates that the photochemical production of ozone from primary pollutants emitted over such

  16. Can seasonal and interannual variation in landscape CO2 fluxes be detected by atmospheric observations of CO2 concentrations made at a tall tower?

    Directory of Open Access Journals (Sweden)

    T. L. Smallman

    2013-08-01

    Full Text Available The Weather Research and Forecasting (WRF meteorological model has been coupled to the Soil Plant Atmosphere (SPA terrestrial ecosystem model, hereafter known as WRF-SPA. SPA generates realistic land-atmosphere exchanges through fully coupled hydrological, carbon and energy cycles. Here we have used WRF-SPA to investigate regional scale observations of atmospheric CO2 concentrations made over a multi-annual period from a tall tower in Scotland. WRF-SPA realistically models both seasonal and daily cycles, predicting CO2 at the tall tower (R2 = 0.67, RMSE = 3.5 ppm, bias = 0.58 ppm, indicating realistic transport, and appropriate source sink distribution and magnitude of CO2 exchange. We have highlighted a consistent post harvest increase in model-observation residuals in atmospheric CO2 concentrations. This increase in model-observation residuals post harvest is likely related to a lack of an appropriate representation of uncultivated components (~ 36% of agricultural holding in Scotland of agricultural land (e.g., hedgerows and forest patches which continue to photosynthesise after the crop has been harvested. Through the use of ecosystem specific CO2 tracers we have shown that tall tower observations here do not detect a representative fraction of Scotland's ecosystem CO2 uptake. Cropland CO2 uptake is the dominant ecosystem signal detected at the tall tower, consistent with the dominance of cropland in the area surrounding the tower. However cropland is over-represented in the atmospheric CO2 concentrations simulated to be at the tall tower, relative to the simulated surface cropland CO2 uptake. Observations made at the tall tower were able to detect seasonal variation in ecosystem CO2 uptake, however a majority of variation was only detected for croplands. We have found evidence that interannual variation in weather has a greater impact than interannual variation of the simulated land surface CO2 exchange on tall tower observations for the

  17. Variation in the Chemical Driving Force for Intragranular Nucleation in the Multi-pass Weld Metal of Ti-Containing High-Strength Low-Alloy Steel

    Science.gov (United States)

    Kang, Yongjoon; Han, Kyutae; Park, Joo Hyun; Lee, Changhee

    2015-08-01

    The variation of the Mn-depleted zone (MDZ) around the inclusion during multi-pass welding of Ti-containing high-strength low-alloy (HSLA) steel was investigated by taking the changes in the impact toughness and microstructure into account. As-deposited weld metal specimens were prepared by single-pass, bead-in-groove welding, and reheated weld metal specimens were obtained by a thermal simulation technique. Two types of chemical compositions were prepared, mainly by controlling the Ti content in order to form two types of phases at inclusion/matrix interface: spinel and ilmenite. When the reheating thermal cycle is applied to the as-deposited weld metal, the MDZ depth varied depending on the inclusion surface phase; this could be explained by the competition of the homogenization effect and the dissolution effect, which occurred near the inclusion/matrix interface. In order to enhance the chemical driving force for intragranular nucleation in both as-deposited weld metal and reheated weld metal, the formation of ilmenite phase is recommended.

  18. IASI observations of seasonal and day-to-day variations of tropospheric ozone over three highly populated areas of China: Beijing, Shanghai, and Hong Kong

    Science.gov (United States)

    Dufour, G.; Eremenko, M.; Orphal, J.; Flaud, J.-M.

    2010-04-01

    IASI observations of tropospheric ozone over the Beijing, Shanghai and Hong Kong areas during one year (2008) have been analysed, demonstrating the capability of space-borne infrared nadir measurements to probe seasonal and even day-to-day variations of lower tropospheric ozone (0-6 km partial columns) on the regional scale of highly populated areas. The monthly variations of lower tropospheric ozone retrieved from IASI clearly show the influence of the Asian summer monsoon that brings clean air masses from the Pacific during summer. They exhibit indeed a sharp ozone maximum in late spring and early summer (May-June) followed by a summer minimum. The time periods and the intensities of the maxima and of the decreases are latitude-dependent: they are more pronounced in Hong Kong and Shanghai than in Beijing. Moreover, IASI provides the opportunity to follow the spatial variations of ozone over the surroundings of each megacity as well as its daily variability. We show here that the large lower tropospheric ozone amounts (0-6 km partial columns) observed with IASI are mainly downwind the highest populated areas in each region, thus possibly suggesting the anthropogenic origin of the large ozone amounts observed. Finally, an analysis of the mean ozone profiles over each region - for selected days with high ozone events - in association with the analysis of the meteorological situation shows that the high ozone amounts observed during winter are likely related to descents of ozone-rich air from the stratosphere, whereas in spring and summer the tropospheric ozone is likely enhanced by photochemical production in polluted areas and/or in air masses from fire plumes.

  19. Earthquake Related Variation of Total Electron Content in Ionosphere over Chinese Mainland Derived from Observations of a Nationwide GNSS Network

    Science.gov (United States)

    Gan, Weijun

    2016-07-01

    Crustal Movement Observation Network of China (CMONOC) is a key national scientific infrastructure project carried out during 1997-2012 with 2 phases. The network is composed of 260 continuously observed GNSS stations (CORS) and 2081 campaign mode GNSS stations, with the main purpose to monitor the crustal movement, perceptible water vapor (PWV), total electron content (TEC), and many other tectonic and environmental elements around mainland China, by mainly using the Global Navigation Satellite System (GNSS) technology. Here, based on the GNSS data of 260 CORS of COMNOC for about 5 years, we investigated the characteristics of TEC in ionosphere over Chinese Mainland and discussed if there was any abnormal change of TEC before and after a big earthquake. our preliminary results show that it is hard to see any convincing precursor of TEC before a big earthquake. However, the huge energy released by a big earthquake can obviously disturb the TEC over meizoseismal area.

  20. In-situ determination of metallic variation and multi-association in single particles by combining synchrotron microprobe, sequential chemical extraction and multivariate statistical analysis

    International Nuclear Information System (INIS)

    Highlights: • A comprehensive method for detecting individual particles was proposed. • The metallic distribution, speciation and correlation in particles were detected. • The metallic variation under different chemical environments was elucidated. • Cu/Zn and Fe/Mn/Cr/Ni were associated with each other and matrix in APC residues. • Metals existed as amorphous forms besides as chlorides and oxides in APC residues. - Abstract: Due to the heterogeneity of metal distribution, it is challenging to identify the speciation, source and fate of metals in solid samples at micro scales. To overcome these challenges single particles of air pollution control residues were detected in situ by synchrotron microprobe after each step of chemical extraction and analyzed by multivariate statistical analysis. Results showed that Pb, Cu and Zn co-existed as acid soluble fractions during chemical extraction, regardless of their individual distribution as chlorides or oxides in the raw particles. Besides the forms of Fe2O3, MnO2 and FeCr2O4, Fe, Mn, Cr and Ni were closely associated with each other, mainly as reducible fractions. In addition, the two groups of metals had interrelations with the Si-containing insoluble matrix. The binding could not be directly detected by micro-X-ray diffraction (μ-XRD) and XRD, suggesting their partial existence as amorphous forms or in the solid solution. The combined method on single particles can effectively determine metallic multi-associations and various extraction behaviors that could not be identified by XRD, μ-XRD or X-ray absorption spectroscopy. The results are useful for further source identification and migration tracing of heavy metals

  1. Variation of Jupiter's aurora observed by Hisaki/EXCEED:2. estimations of auroral parameters and magnetospheric dynamics

    OpenAIRE

    Tao, Chihiro; Kimura, Tomoki; Badman, Sarah V.; André, Nicolas; Tsuchiya, Fuminori; Murakami, Go; Yoshioka, Kazuo; Yoshikawa, Ichiro; Yamazaki, Atsushi; Fujimoto, Masaki

    2016-01-01

    Jupiter's auroral parameters are estimated from observations by a spectrometer EXCEED (Extreme Ultraviolet Spectroscope for Exospheric Dynamics) onboard JAXA's Earth-orbiting planetary space telescope Hisaki. EXCEED provides continuous auroral spectra covering the wavelength range over 80–148 nm from the whole northern polar region. The auroral electron energy is estimated using a hydrocarbon color ratio adopted for the wavelength range of EXCEED, and the emission power in the long wavelength...

  2. Chemical and Isotopic Variations with Depth: a Detailed Saturated Zone Profile of a 140m Thick Coastal Aquifer

    Science.gov (United States)

    Raanan, H.; Ronen, D.; Weisbrod, N.; Dahan, O.; Seiler, K.; Vengosh, A.

    2005-12-01

    A percussion borehole was constructed through the saturated zone of the Mediterranean coastal aquifer in Tel Aviv, Israel, penetrating its three subaquifers and the upper part of the underlying Saqiye aquitard. The research site was previously subjected to direct industrial contamination and is currently exposed to the industrial contaminants in the outskirts of the densely populated Tel Aviv metropolis. Here we report the results of a large variety of analysis conducted on the 140m saturated profile that included field measurements (e.g. dissolved oxygen, pH, temperature, conductivity), major elements (e.g. Cl-, SO42-, HCO3-, NO3-, Ca2+, K+, Na+), trace elements (e.g. Pb, Fe, Cu) and radium isotopic measurements (223Ra, 224Ra, 226Ra). A clear distinction between the units becomes evident along the vertical profile; the upper phreatic unit (A) appears to be more saline relative to the central unit (B) (TDS of 734 and 670 mg/L, respectively). The deep unit (C) is significantly more saline in its lower part (up to 860 mg/L). We observed two nitrate peaks in the central zones of subaquifers B and C. The high nitrate peaks are associated with low Na/Cl and high Ca/Cl ratios. The 224Ra/223Ra ratio also changes with depth; in the upper and the lower subaquifers the relatively low 224Ra/223Ra ratios (50) indicates a larger fraction of a uranium source whereas in the central zone of the aquifer high 224Ra/223Ra ratios reflect rather a predominant thorium source for the dissolved radium. The data obtained through this borehole allows a rare investigation of the heterogeneity of water quality and composition in a coastal aquifer. The data provides characterization of different end-members along the saturated zone and also indicates the different proportions of lateral versus vertical flows of groundwater in a porous media.

  3. A large enhancement of the solar diurnal variation observed underground and at the surface at southern latitudes in April 1980

    International Nuclear Information System (INIS)

    Large enhancements of amplitude of the solar diurnal component have been observed with neutron monitors and underground telescopes at Mawson and Hobart and with the neutron monitor at Darwin, over the period 2-9 April 1980. A remarkable feature has been an average four-fold increase in underground amplitude compared with a two-fold increase in the high-latitude neutron amplitude. Contributions to the enhancement, due to changes in free-space amplitude and upper limiting rigidity, are investigated and discussed

  4. Observation of seasonal variation of atmospheric multiple-muon events in the MINOS Near and Far Detectors

    OpenAIRE

    Adamson, P.; Anghel, I.; Aurisano, A.; Barr, G.; Bishai, M.; Blake, A.; Bock, G.J.; Bogert, D.; Cao, S. V.; Castromonte, C. M.; Childress, S.; Coelho, J. A. B.; Corwin, L.; Cronin-Hennessy, D.; de Jong, J. K.

    2015-01-01

    We report the first observation of seasonal modulations in the rates of cosmic ray multiple-muon events at two underground sites, the MINOS Near Detector with an overburden of 225 mwe, and the MINOS Far Detector site at 2100 mwe. At the deeper site, multiple-muon events with muons separated by more than 8 m exhibit a seasonal rate that peaks during the summer, similar to that of single-muon events. In contrast and unexpectedly, the rate of multiple-muon events with muons separated by less tha...

  5. Solar minimum Lyman alpha sky background observations from Pioneer Venus orbiter ultraviolet spectrometer - Solar wind latitude variation

    Science.gov (United States)

    Ajello, J. M.

    1990-01-01

    Measurements of interplanetary H I Lyman alpha over a large portion of the celestial sphere were made at the recent solar minimum by the Pioneer Venus orbiter ultraviolet spectrometer. These measurements were performed during a series of spacecraft maneuvers conducted to observe Halley's comet in early 1986. Analysis of these data using a model of the passage of interstellar wind hydrogen through the solar system shows that the rate of charge exchange with solar wind protons is 30 percent less over the solar poles than in the ecliptic. This result is in agreement with a similar experiment performed with Mariner 10 at the previous solar minimum.

  6. The influence of variations of the Earth' magnetic field on the elaboration of geomagnetic observations in Poland

    Science.gov (United States)

    Welker, E.

    2012-06-01

    The increase of accuracy of magnetic measurements generated the need of testing of the influence of variations of the geomagnetic field on their elaboration. On the basis of the magnetic data obtained from European observatories and from magnetic stations operating in 2010 and 2011, the chart of amplitude changes of Y magnetic field component (magnetic declination too) in Poland and the chart of time shift between the records of Belsk Observatory - considered as central observatory - as well as the records from other measurement points were processed. Data from some geomagnetic stations operating in the 1960. (with records of D, H and Z components) stored in the database at the Institute of Geodesy and Cartography, Warsaw, were re used to analyse geomagnetic field intensity changes (Uhrynowski, 1962, 1964). The error of transforming analogue data from paper records to the digital form is bigger than amplitude changes of declination D and H component. The results of Fourier transformation of millions of data from magnetic observatories allowed for mapping the distribution of amplitude changes of Y component and time shift of records from chosen European observatories with respect to Belsk Observatory. The range of amplitude changes of the X, Y and Z components of the geomagnetic field intensity in Poland is exceptionally small. It reaches only ±2-3 nT which is at the level of the error of geomagnetic data elaboration. The range of time shift of the record from points by eastern border of Poland with respect to those by western border of Poland vary from -6 to +15 minutes for Y component. The test made with data from secular point (repeat station) measurements from 2009-2011 shows that the differences between results obtained without and with time corrections reach only 10-302 for declination and inclination, and 5 nT for total intensity vector length. The use of the magnetograms from Belsk Observatory for the geomagnetic measurement reduction without any time

  7. Long-term trend and spatiotemporal variations of haze over China by satellite observations from 1979 to 2013

    Science.gov (United States)

    Zhang, Xingying; Wang, Ling; Wang, Weihe; Cao, Dongjie; Wang, Xi; Ye, Dianxiu

    2015-10-01

    With the fast development of economy and industry in the past thirty years, many large cities in the eastern and southwestern areas of China are experiencing increased haze events and atmospheric pollution, which causes significant impacts on the regional environment, human health, and even climate. The long-term trend and spatiotemporal variations of haze over China during recent 30 years are investigated using TOMS AAI products. In addition, the heavy haze events that occurred in January 2013 over eastern China are explored using AAI products from TOU on board FY-3A. Validation results show that satellite AAI products can be used for haze monitoring since it is sensitive to the carbonaceous aerosol, which is one of the main components of haze. In China, the high AAI values (>1.0) mainly located in the main four areas with intense anthropogenic activities, except for the desert region in Northwestern China. In the eastern and northeastern region, AAI peaks dominate in spring before 2005 since those areas were always affected by dust in spring. However, after 2005, AAI peaks appear in winter over eastern China because of haze. Moreover, in the northeastern region, AAI peaks dominate in winter with a secondary peak in spring because this area is affected by both dust and haze. In the southern region, the AAI peaks always dominate in spring since the high-level air pollution often occur in spring, but a decreasing trend is acquired during recent ten years. Over eastern China and northeastern China, AAI shows an increasing trend during recent 30 years in winter, which reveals that the haze over these areas is strengthen. A case study result shows that the heavy haze events occurred in January 2013 in eastern China can be clearly identified from the AAI products of TOU/FY-3A. The daily coverage area with AAI > 3.0 peaks at five periods at this time, i.e. Jan. 7-8, Jan. 13, Jan. 18, Jan. 23, and, Jan. 28-29, which agrees well with the haze events recorded by in

  8. Temporal Variations of Titan's Middle-Atmospheric Temperatures from 2004 to 2009 Observed by Cassini/CIRS

    Science.gov (United States)

    Achterberg, Richard K.; Gierasch, Peter J.; Conrath, Barney J.; Flasar, F. Michael; Nixon, Conor A.

    2011-01-01

    We use five and one-half years of limb- and nadir-viewing temperature mapping observations by the Composite Infrared Radiometer-Spectrometer (CIRS) on the Cassini Saturn orbiter, taken between July 2004 and December 2009 (Ls from 293 deg. to 48 deg.; northern mid-winter to just after northern spring equinox), to monitor temperature changes in the upper stratosphere and lower mesosphere of Titan. The largest changes are in the northern (winter) polar stratopause, which has declined in temperature by over 20 K between 2005 and 2009. Throughout the rest of the mid to upper stratosphere and lower mesosphere, temperature changes are less than 5 K. In the southern hemisphere, temperatures in the middle stratosphere near 1 mbar increased by 1-2 K from 2004 through early 2007, then declined by 2-4 K throughout 2008 and 2009, with the changes being larger at more polar latitudes. Middle stratospheric temperatures at mid-northern latitudes show a small 1-2 K increase from 2005 through 2009, at north polar latitudes within the polar vortex, temperatures in the middle stratosphere show an approximately 4 K increase during 2007, followed by a comparable decrease in temperatures in 2008 and into early 2009. The observed temperature changes in the north polar region are consistent with a weakening of the subsidence within the descending branch of the middle atmosphere meridional circulation.

  9. Remote sensing observations and numerical studies of a super typhoon-induced suspended sediment concentration variation in the East China Sea

    Science.gov (United States)

    Li, Yangdong; Li, Xiaofeng

    2016-08-01

    By integrating remote sensing observations and a numerical modeling technique, we studied the influences of super Typhoon Saomai on the suspended sediment concentration (SSC) in the Yangtze River estuary and its adjacent coastal areas in the East China Sea. First, three consecutive Moderate Resolution Imaging Spectroradiometer (MODIS) images acquired during the post-typhoon stage were used to estimate the SSC. Then, we implemented a hydrodynamic model, including a sediment transport module, based on Delft3D to simulate the sediment erosion, re-suspension, transport and deposition processes in the study area during the passage of Typhoon Saomai. The model-simulated water level was validated against the in situ station data to show the feasibility of the model. The simulated SSC results agree reasonably well with the satellite observations. Time series of the simulation results showed that the model revealed the whole SSC variations during this extreme weather event and made up for the scarcity of in-situ and satellite observations. SSC significantly increased during the passage of the typhoon and decreased gradually during the post-typhoon stage. Modeled results also reveal that the spring-neap tidal effect significantly controlled the distribution and variation of SSC in the shallower coastal water (typhoon-induced re-suspension is evident in most of the study area, especially in the coastal waters near the Yangtze River estuary and Hangzhou Bay during the passage of the typhoon. Finally, based on the simulation results, we discuss the dynamic mechanisms including turbulent energy, bed shear stress and vertical mixing that caused the SSC variation.

  10. NEOCAM: Near Earth Object Chemical Analysis Mission: Bridging the Gulf between Telescopic Observations and the Chemical and Mineralogical Compositions of Asteroids or Diogenes A: Diagnostic Observation of the Geology of Near Earth Spectrally-Classified Asteroids

    Science.gov (United States)

    Nuth, Joseph A.

    2009-01-01

    Studies of meteorites have yielded a wealth of scientific information based on highly detailed chemical and isotopic studies possible only in sophisticated terrestrial laboratories. Telescopic studies have revealed an enormous (greater than 10(exp 5)) number of physical objects ranging in size from a few tens of meters to several hundred kilometers, orbiting not only in the traditional asteroid belt between Mars and Jupiter but also throughout the inner solar system. Many of the largest asteroids are classed into taxonomic groups based on their observed spectral properties and are designated as C, D. X, S or V types (as well as a wide range in sub-types). These objects are certainly the sources far the meteorites in our laboratories, but which asteroids are the sources for which meteorites? Spectral classes are nominally correlated to the chemical composition and physical characteristics of the asteroid itself based on studies of the spectral changes induced in meteorites due to exposure to a simulated space environment. While laboratory studies have produced some notable successes (e.g. the identification of the asteroid Vesta as the source of the H, E and D meteorite classes), it is unlikely that we have samples of each asteroidal spectral type in our meteorite collection. The correlation of spectral type and composition for many objects will therefore remain uncertain until we can return samples of specific asteroid types to Earth for analyses. The best candidates for sample return are asteroids that already come close to the Earth. Asteroids in orbit near 1 A.U. have been classified into three groups (Aten, Apollo & Amor) based on their orbital characteristics. These Near Earth Objects (NEOs) contain representatives of virtually all spectral types and sub-types of the asteroid population identified to date. Because of their close proximity to Earth, NEOs are prime targets for asteroid missions such as the NEAR-Shoemaker NASA Discovery Mission to Eros and the

  11. Chemical composition of modern and fossil Hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation - Part 1: Major and minor element variation

    Science.gov (United States)

    Brügmann, G.; Krause, J.; Brachert, T. C.; Kullmer, O.; Schrenk, F.; Ssemmanda, I.; Mertz, D. F.

    2012-01-01

    Bioapatite in mammalian teeth is readily preserved in continental sediments and represents a very important archive for reconstructions of environment and climate evolution. This project provides a comprehensive data base of major, minor and trace element and isotope tracers for tooth apatite using a variety of microanalytical techniques. The aim is to identify specific sedimentary environments and to improve our understanding on the interaction between internal metabolic processes during tooth formation and external nutritional control and secondary alteration effects. Here, we use the electron microprobe to determine the major and minor element contents of fossil and modern molar enamel, cement and dentin from Hippopotamids. Most of the studied specimens are from different ecosystems in Eastern Africa, representing modern and fossil lacustrine (Lake Kikorongo, Lake Albert, and Lake Malawi) and modern fluvial environments of the Nile River system. Secondary alteration effects - in particular FeO, MnO, SO3 and F concentrations - are 2 to 10 times higher in fossil than in modern enamel; the secondary enrichment of these components in fossil dentin and cement is even higher. In modern and fossil enamel, along sections perpendicular to the enamel-dentin junction (EDJ) or along cervix-apex profiles, P2O5 and CaO contents and the CaO/P2O5 ratios are very constant (StdDev ∼1%). Linear regression analysis reveals tight control of the MgO (R2∼0.6), Na2O and Cl variation (for both R2>0.84) along EDJ-outer enamel rim profiles, despite large concentration variations (40% to 300%) across the enamel. These minor elements show well defined distribution patterns in enamel, similar in all specimens regardless of their age and origin, as the concentration of MgO and Na2O decrease from the enamel-dentin junction (EDJ) towards the outer rim, whereas Cl displays the opposite trend. Fossil enamel from Hippopotamids which lived in the saline Lake Kikorongo have a much higher MgO/Na2

  12. Observation of seasonal variation of atmospheric multiple-muon events in the MINOS near and far detectors

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, P. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States). et al.

    2015-06-09

    We report the first observation of seasonal modulations in the rates of cosmic ray multiple-muon events at two underground sites, the MINOS Near Detector with an overburden of 225 mwe, and the MINOS Far Detector site at 2100 mwe. Thus, at the deeper site, multiple-muon events with muons separated by more than 8 m exhibit a seasonal rate that peaks during the summer, similar to that of single-muon events. In contrast and unexpectedly, the rate of multiple-muon events with muons separated by less than 5–8 m, and the rate of multiple-muon events in the smaller, shallower Near Detector, exhibit a seasonal rate modulation that peaks in the winter.

  13. Observation of seasonal variation of atmospheric multiple-muon events in the MINOS Near and Far Detectors

    CERN Document Server

    Adamson, P; Aurisano, A; Barr, G; Bishai, M; Blake, A; Bock, G J; Bogert, D; Cao, S V; Castromonte, C M; Childress, S; Coelho, J A B; Corwin, L; Cronin-Hennessy, D; de Jong, J K; Devan, A V; Devenish, N E; Diwan, M V; Escobar, C O; Evans, J J; Falk, E; Feldman, G J; Frohne, M V; Gallagher, H R; Gomes, R A; Goodman, M C; Gouffon, P; Graf, N; Gran, R; Grzelak, K; Habig, A; Hahn, S R; Hartnell, J; Hatcher, R; Holin, A; Huang, J; Hylen, J; Irwin, G M; Isvan, Z; James, C; Jensen, D; Kafka, T; Kasahara, S M S; Koizumi, G; Kordosky, M; Kreymer, A; Lang, K; Ling, J; Litchfield, P J; Lucas, P; Mann, W A; Marshak, M L; Mayer, N; McGivern, C; Medeiros, M M; Mehdiyev, R; Meier, J R; Messier, M D; Miller, W H; Mishra, S R; Sher, S Moed; Moore, C D; Mualem, L; Musser, J; Naples, D; Nelson, J K; Newman, H B; Nichol, R J; Nowak, J A; Connor, J O; Orchanian, M; Osprey, S; Pahlka, R B; Paley, J; Patterson, R B; Pawloski, G; Perch, A; Phan-Budd, S; Plunkett, R K; Poonthottathil, N; Qiu, X; Radovic, A; Rebel, B; Rosenfeld, C; Rubin, H A; Sanchez, M C; Schneps, J; Schreckenberger, A; Schreiner, P; Sharma, R; Sousa, A; Tagg, N; Talaga, R L; Thomas, J; Thomson, M A; Tian, X; Timmons, A; Tognini, S C; Toner, R; Torretta, D; Urheim, J; Vahle, P; Viren, B; Weber, A; Webb, R C; White, C; Whitehead, L; Whitehead, L H; Wojcicki, S G; Zwaska, R

    2015-01-01

    We report the first observation of seasonal modulations in the rates of cosmic ray multiple-muon events at two underground sites, the MINOS Near Detector with an overburden of 225 mwe, and the MINOS Far Detector site at 2100 mwe. At the deeper site, multiple-muon events with muons separated by more than 8 m exhibit a seasonal rate that peaks during the summer, similar to that of single-muon events. In contrast and unexpectedly, the rate of multiple-muon events with muons separated by less than 5-8 m, and the rate of multiple-muon events in the smaller, shallower Near Detector, exhibit a seasonal rate modulation that peaks in the winter.

  14. Methodology for evaluating lateral boundary conditions in the regional chemical transport model MATCH (v5.5.0) using combined satellite and ground-based observations

    Science.gov (United States)

    Andersson, E.; Kahnert, M.; Devasthale, A.

    2015-11-01

    Hemispheric transport of air pollutants can have a significant impact on regional air quality, as well as on the effect of air pollutants on regional climate. An accurate representation of hemispheric transport in regional chemical transport models (CTMs) depends on the specification of the lateral boundary conditions (LBCs). This study focuses on the methodology for evaluating LBCs of two moderately long-lived trace gases, carbon monoxide (CO) and ozone (O3), for the European model domain and over a 7-year period, 2006-2012. The method is based on combining the use of satellite observations at the lateral boundary with the use of both satellite and in situ ground observations within the model domain. The LBCs are generated by the global European Monitoring and Evaluation Programme Meteorological Synthesizing Centre - West (EMEP MSC-W) model; they are evaluated at the lateral boundaries by comparison with satellite observations of the Terra-MOPITT (Measurements Of Pollution In The Troposphere) sensor (CO) and the Aura-OMI (Ozone Monitoring Instrument) sensor (O3). The LBCs from the global model lie well within the satellite uncertainties for both CO and O3. The biases increase below 700 hPa for both species. However, the satellite retrievals below this height are strongly influenced by the a priori data; hence, they are less reliable than at, e.g. 500 hPa. CO is, on average, underestimated by the global model, while O3 tends to be overestimated during winter, and underestimated during summer. A regional CTM is run with (a) the validated monthly climatological LBCs from the global model; (b) dynamical LBCs from the global model; and (c) constant LBCs based on in situ ground observations near the domain boundary. The results are validated against independent satellite retrievals from the Aqua-AIRS (Atmospheric InfraRed Sounder) sensor at 500 hPa, and against in situ ground observations from the Global Atmospheric Watch (GAW) network. It is found that (i) the use of

  15. Day and night variation in chemical composition and toxicological responses of size segregated urban air PM samples in a high air pollution situation

    Science.gov (United States)

    Jalava, P. I.; Wang, Q.; Kuuspalo, K.; Ruusunen, J.; Hao, L.; Fang, D.; Väisänen, O.; Ruuskanen, A.; Sippula, O.; Happo, M. S.; Uski, O.; Kasurinen, S.; Torvela, T.; Koponen, H.; Lehtinen, K. E. J.; Komppula, M.; Gu, C.; Jokiniemi, J.; Hirvonen, M.-R.

    2015-11-01

    Urban air particulate pollution is a known cause for adverse human health effects worldwide. China has encountered air quality problems in recent years due to rapid industrialization. Toxicological effects induced by particulate air pollution vary with particle sizes and season. However, it is not known how distinctively different photochemical activity and different emission sources during the day and the night affect the chemical composition of the PM size ranges and subsequently how it is reflected to the toxicological properties of the PM exposures. The particulate matter (PM) samples were collected in four different size ranges (PM10-2.5; PM2.5-1; PM1-0.2 and PM0.2) with a high volume cascade impactor. The PM samples were extracted with methanol, dried and thereafter used in the chemical and toxicological analyses. RAW264.7 macrophages were exposed to the particulate samples in four different doses for 24 h. Cytotoxicity, inflammatory parameters, cell cycle and genotoxicity were measured after exposure of the cells to particulate samples. Particles were characterized for their chemical composition, including ions, element and PAH compounds, and transmission electron microscopy (TEM) was used to take images of the PM samples. Chemical composition and the induced toxicological responses of the size segregated PM samples showed considerable size dependent differences as well as day to night variation. The PM10-2.5 and the PM0.2 samples had the highest inflammatory potency among the size ranges. Instead, almost all the PM samples were equally cytotoxic and only minor differences were seen in genotoxicity and cell cycle effects. Overall, the PM0.2 samples had the highest toxic potential among the different size ranges in many parameters. PAH compounds in the samples and were generally more abundant during the night than the day, indicating possible photo-oxidation of the PAH compounds due to solar radiation. This was reflected to different toxicity in the PM

  16. Seasonal variation of ozone and black carbon observed at Paknajol, an urban area in the Kathmandu Valley, Nepal

    Science.gov (United States)

    Putero, Davide; Cristofanelli, Paolo; Marinoni, Angela; Adhikary, Bhupesh; Duchi, Rocco; Das Shrestha, Sunil; Pietro Verza, Gian; Landi, Tony Christian; Calzolari, Francescopiero; Busetto, Maurizio; Agrillo, Giacomo; Biancofiore, Fabio; Di Carlo, Piero; Panday, Arnico; Rupakheti, Maheswar; Bonasoni, Paolo

    2016-04-01

    The Kathmandu Valley in the Himalayan foothills, considered as one of the global "hot spots" for what concerns air pollution, is currently facing severe air quality problems due to rapid urbanization processes, dramatic land use changes, socioeconomic transformation and high population growth. In this work, we present the first full year (February 2013 - February 2014) analysis of simultaneous measurements of two short-lived climate forcers/pollutants (SLCF/P), i.e. ozone (O3) and equivalent black carbon (BC), and aerosol number concentration at Paknajol (27°43'4'' N, 85°18'32'' E, 1380 m a.s.l.), in the city center of Kathmandu. These observations were carried out in the framework of the SusKat-ABC (A Sustainable Atmosphere for the Kathmandu Valley - Atmospheric Brown Cloud) campaign in Nepal. The diurnal behavior of BC and aerosol number concentration indicated that local pollution sources represent the major contribution to air pollution in this city. In addition to photochemistry, the planetary boundary layer (PBL) dynamic plays an important role in determining O3 variability, as suggested by the analysis of seasonal changes of the diurnal cycles and the correlation with meteorological parameters and aerosol properties. Especially during pre-monsoon, high values of O3 were observed during the afternoon/evening. This could be related to mixing and entrainment processes between upper residual layers and the PBL. During this season, the high O3 appeared well related to the impact of major open vegetation fires occurring in Nepal. On a synoptic-scale perspective, westerly and regional atmospheric circulations appeared to be especially conducive for the occurrence of the high BC and O3 values. The very high values of the SLCF/P, detected during the whole measurement period, indicated persisting adverse air quality conditions, dangerous for the health of over 3 million residents of the Kathmandu Valley, and the environment. Consequently, all of this information may

  17. Temporal variation of soil moisture over the Wuding River Basin assessed with an eco-hydrological model, in-situ observations and remote sensing

    Directory of Open Access Journals (Sweden)

    S. Liu

    2008-12-01

    Full Text Available For integrative management of soil and water in the Wuding River basin, Loess plateau, China, where severe soil erosion damages are incurred, the ecohydrological behavior of the region is needed to be explored. In this study we focus on the evolution of soil moisture (SM in the basin. Since there are only twelve years in-situ SM measurements available at two stations from 1992 to 2004, an eco-hydrological processes-based model (VIP, Vegetation Interface Processes model is employed to simulate the long-term SM, evapotranspiration (ET, vegetation cover and production variation from 1956 to 2004, for the mechanical analysis of SM change. In-situ SM observations and a remotely sensed SM dataset retrieved by the Vienna University of Technology are used to validate the model. The results show that the model is able to capture seasonal SM variations. The seasonal pattern, multi-year variation, standard deviation and CV (coefficient of the variation of SM at the daily, monthly and annual scale are well explained by the climatic and ecological factors such as precipitation, temperature, net radiation, evapotranspiration, and Leaf Area Index (LAI, denoted as LAI. The annual and inter-annual variability of SM is the lowest comparing with that for other 11-ecohydrological variables. The trend analysis shows that SM is in decreasing tendency at ∝=0.01 level of significance. Its significance is lower than that of runoff and that of temperature (∝=0.001, whereas higher than that of precipitation (∝=0.1. The products of these long-term SM data aim to help integrative management of soil and water resources.

  18. The Association between Seasonal Variation in Vitamin D, Postural Sway, and Falls Risk: An Observational Cohort Study

    Directory of Open Access Journals (Sweden)

    Marie-Louise Bird

    2013-01-01

    Full Text Available Introduction. Low serum vitamin D levels are associated with increased postural sway. Vitamin D varies seasonally. This study investigates whether postural sway varies seasonally and is associated with serum vitamin D and falls. Methods. In a longitudinal observational study, eighty-eight independently mobile community-dwelling older adults (69.7 ± 7.6 years were evaluated on five occasions over one year, measuring postural sway (force platform, vitamin D levels, fall incidence, and causes and adverse outcomes. Mixed-methods Poisson regression was used to determine associations between measures. Results. Postural sway did not vary over the year. Vitamin D levels varied seasonally (P<0.001, peaking in summer. Incidence of falls (P=0.01 and injurious falls (P=0.02 were lower in spring, with the highest fall rate at the end of autumn. Postural sway was not related to vitamin D (P=0.87 or fall rates, but it was associated with fall injuries (IRR 1.59 (CI 1.14 to 2.24, P=0.007. Conclusions. Postural sway remained stable across the year while vitamin D varied seasonally. Participants with high values for postural sway demonstrated higher rates of injurious falls. This study provides important evidence for clinicians and researchers providing interventions measuring balance outcomes across seasons.

  19. Observation of the Existing Boreholes, Analysis of the Produced Data, and Modelling of the Long-term Variation

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Sung Oong; Kim, J. Y.; Sung, I. H.; Shin, H. S.; Cho, B. O.; Syhn, J. H.; Park, C.; Hyun, H. J. [Korea Institute of Geology, Mining and Materials, Taejon (Korea, Republic of)

    1997-11-01

    Long-term observations on the ground water, classification on the rock mass via seismic tomography, and in-situ measurements by the hydraulic fracturing technique were performed to construct KAERI research tunnel for high-level radioactive waste disposal. Water level was checked for 7 boreholes and the quality of the ground water was analyzed for 4 boreholes. Statistical analysis on the discontinuity and the results of the water pressure test were reevaluated through the results of the borehole televiewer prospecting. And with the seismic tomographic prospectings on the BH3-BH5 section and the BH5-BH6 section, the condition of the rock amss was classified very clearly. Furthermore the in-situ stress was measured for BH3 and BH5 boreholes by hydraulic fracturing techniques, and these results were compared to the other data obtained by overcoring method. Also the lugeon test was performed, even through it is some apparent, on the natural crack with the hydraulic fracturing system, and we could obtain the permeability for that joint. 46 refs., 10 tabs., 64figs. (author)

  20. A model for predicting changes in the electrical conductivity, practical salinity, and absolute salinity of seawater due to variations in relative chemical composition

    Directory of Open Access Journals (Sweden)

    R. Pawlowicz

    2009-11-01

    Full Text Available Salinity determination in seawater has been carried out for almost 30 years using the 1978 Practical Salinity Standard. However, the numerical value of so-called practical salinity, computed from electrical conductivity, differs slightly from the true or absolute salinity, defined as the mass of dissolved solids per unit mass of seawater. The difference arises because more recent knowledge about the composition of seawater is not reflected in the definition of practical salinity, which was chosen to maintain historical continuity with previous measures, and because of spatial and temporal variations in the relative composition of seawater. Accounting for these variations in density calculations requires the calculation of a correction factor δSA, which is known to range from 0 to 0.03 g kg−1 in the world oceans. Here a mathematical model relating compositional perturbations to δSA is developed, by combining a chemical model for the composition of seawater with a mathematical model for predicting the conductivity of multi-component aqueous solutions. Model calculations generally agree with estimates of δSA based on fits to direct density measurements, and show that biogeochemical perturbations affect conductivity only weakly. However, small systematic differences between model and density-based estimates remain. These may arise for several reasons, including uncertainty about the biogeochemical processes involved in the increase in Total Alkalinity in the North Pacific, uncertainty in the carbon content of IAPSO standard seawater, and uncertainty about the haline contraction coefficient for the constituents involved in biogeochemical processes. This model may then be important in constraining these processes, as well as in future efforts to improve parameterizations for δSA.