WorldWideScience

Sample records for chemical variations observed

  1. Chemical variations observed on Aeolis Mons in Gale Crater, Mars

    Science.gov (United States)

    Frydenvang, Jens; Gasda, Patrick J.; Thompson, Lucy; Hurowitz, Joel; Grotzinger, John P.; Blaney, Diana L.; Gellert, Ralf; Wiens, Roger; Vasavada, Ashwin R.; MSL Science Team

    2016-10-01

    The extraordinarily extensive exposure of hematite-, clay-, sulfate-bearing stratigraphic layers in the lower part of Aeolis Mons was the primary reason Gale Crater was selected as the landing site for the Mars Science Laboratory rover, Curiosity. 753 martian solar days (sols) after the Curiosity rover landed in Gale Crater in August 2012, and after driving more than 9 km, the Curiosity rover arrived at the first exposure of the Murray formation, the basal layer of Aeolis Mons. The Murray formation is a thinly laminated lacustrine mudstone showing stratification down to the millimeter scale. This supports the idea that the stratigraphic layers of Aeolis Mons are sedimentary, and likely deposited in a series of long-lived lakes extending into the early Hesperian time, as recently described by Grotzinger et al. (Science, vol. 350, 2015). The chemical variations observed throughout the Murray formation by the ChemCam and APXS instruments in the 600+ sols since first arriving at Aeolis Mons will be presented. While Murray remains thinly laminated throughout the 30+ vertical meters of stratigraphy explored, large chemical variations are observed. The most extreme variations arise from likely co-located detrital and diagenetic silica enrichments in Murray. Remarkably, an associated diagenetic silica enrichment is also observed in the unconformably overlying eolian sandstone of the Stimson formation in that location. The detrital enrichment provides evidence of how the source region chemistry varied as the sedimentary layers of Aeolis Mons were deposited. Conversely, the diagenetic enrichment observed across both the Murray and Stimson formations provides compelling evidence for the presence of subsurface fluids in Gale Crater, thousands to millions of years after the crater lakes disappeared. This evidence of liquid water greatly extends the timescale in which Gale Crater might have been habitable.

  2. 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.

  3. Origin and Chemical Variation of Brazilian Propolis

    Directory of Open Access Journals (Sweden)

    Antonio Salatino

    2005-01-01

    Full Text Available Propolis is a hive product containing chiefly beeswax and plant-derived substances such as resin and volatile compounds. Propolis has been used as an antiseptic and wound healer since ancient times and interest for the product has increased recently. Probably few plant species contribute as major resin sources. Green propolis derives mainly from vegetative apices of Baccharis dracunculifolia (alecrim plants. However, wide variation detected in the chemical composition suggests contributions from alternative resin plant sources. Predominant components of the resin of green propolis are cinnamic acids, chiefly compounds bearing prenyl groups. Terpenoid compounds, such as sesqui, di and pentacyclic triterpenoids, have been detected in many, but not all, samples investigated. Propolis research has uncovered potentialities of substances previously isolated from plants and has detected constituents of plant origin that would hardly be known otherwise.

  4. Observed variations of monopile foundation stiffness

    DEFF Research Database (Denmark)

    Kallehave, Dan; Thilsted, C.L.; Diaz, Alberto Troya

    2015-01-01

    The soil-structure stiffness of monopile foundations for offshore wind turbines has a high impact on the fatigue loading during normal operating conditions. Thus, a robust design must consider the evolution of pile-soil stiffness over the lifetime of the wind farm. This paper present and discuss...... full-scale measurements obtained from one offshore wind turbine structure located within Horns Reef II offshore wind farm. Data are presented for a 2.5 years period and covers normal operating conditions and one larger storm event. A reduction of the pile-soil stiffness was observed during the storm...... events, followed by a complete regain to a pre-storm level when the storm subsided. In additional, no long term variations of the pile-soil stiffness was observed. The wind turbine is located in dense to very dense sand deposits....

  5. Variation of fundamental constants: theory and observations

    CERN Document Server

    Flambaum, V V

    2007-01-01

    Review of recent works devoted to the variation of the fundamental constants is presented including atomic clocks, quasar absorption spectra, and Oklo natural nuclear reactor data. Assuming linear variation with time we can compare different results. From the quasar absorption spectra: $\\dot{\\mu}/\\mu=(1 \\pm 3) \\times 10^{-16}$ yr$^{-1}$. A combination of this result and the atomic clock results gives the best limt on variation of $\\alpha$: $\\dot{\\alpha}/\\alpha=(-0.8 \\pm 0.8) \\times 10^{-16}$ yr$^{-1}$. The Oklo natural reactor gives the best limit on the variation of $m_s/\\Lambda_{QCD}$ where $m_s$ is the strange quark mass. Huge enhancement of the relative variation effects happens in transitions between close atomic, molecular and nuclear energy levels. We suggest several new cases where the levels are very narrow. Large enhancement of the variation effects is also possible in cold atomic and molecular collisions near Feshbach resonance. Massive bodies (stars or galaxies) can also affect physical constants....

  6. 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.

  7. Chemical Data Assimilation &Optimized Earth Observation

    Science.gov (United States)

    Lary, D.

    2003-04-01

    Issues such as ozone depletion, acid rain, and photochemical smog are all of considerable environmental importance. These issues are studied using the dual approach of observations and numerical modelling. In making balanced assessments of these issues it is vital to make the best use of all the information available to us, both theoretical and observational. This is a non-trivial task. The technique of "data assimilation" is a powerful tool which allows us to address this issue. It is revolutionising the way we can study atmospheric chemistry. Data assimilation allows us to simultaneously make good use of however many observations are available to us, our theoretical understanding, and any apriori information we have, within a mathematical framework. It even allows us to infer information about chemical constituents which are not observed. It is a technique which is set to grow in importance. It is also applicable to any system for which we have both observations, a deterministic model, and estimates of uncertainty. Such applications could be from laboratory kinetics to metabolic pathways. Looking ahead we can envision Data assimilation as part of a Optimized Earth Observation System by developing a dynamic data retrieval control system. The dynamic data retrieval control system will dynamically adapt the what, where, and when for the observations made in an online fashion to maximize information content, minimize uncertainty in characterizing the system’s state vector, and minimize both the required storage and data processing time for a given observation capability (with the possibility of even directing unmanned sub-orbital platforms, drones, to make additional observations). This is particularly desirable to facilitate the dynamic tracking of evolving sharp gradients, for example, those in chemical tracer fields often located at the polar vortex edge, the tropopause and the day-night division. The basic idea is the desire for symbiotic communication to

  8. Torsional oscillations and observed rotational period variations in early-type stars

    CERN Document Server

    Krticka, J; Henry, G W; Kurfurst, P; Karlicky, M

    2016-01-01

    Some chemically peculiar stars in the upper main sequence show rotational period variations of unknown origin. We propose these variations are a consequence of the propagation of internal waves in magnetic rotating stars that lead to the torsional oscillations of the star. We simulate the magnetohydrodynamic waves and calculate resonant frequencies for two stars that show rotational variations: CU Vir and HD 37776. We provide updated analyses of rotational period variations in these stars and compare our results with numerical models. For CU Vir, the length of the observed rotational-period cycle, $\\mathit\\Pi=67.6(5)$ yr, can be well reproduced by the models, which predict a cycle length of 51 yr. However, for HD 37776, the observed lower limit of the cycle length, $\\mathit\\Pi\\geq100$ yr, is significantly longer than the numerical models predict. We conclude that torsional oscillations provide a reasonable explanation at least for the observed period variations in CU Vir.

  9. 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 ...

  10. Direct Observations of PMC Local Time Variations by Aura OMI

    Science.gov (United States)

    DeLand, Matthew T.; Shettle, Eric P.; Thomas, Gary E.; Olivero, John J.

    2010-01-01

    The Ozone Monitoring Instrument (OMI) on the Aura satellite obtains unique measurements for polar mesospheric cloud (PMC) analysis. Its wide cross-track viewing swath and high along-track spatial resolution makes it possible to directly evaluate PMC occurrence frequency and brightness variations between 6S" and 8S' latitude as a function of local time over a 12-14 h continuous period. OMI PMC local time variations are closely coupled to concurrent variations in measurement scattering angle, so that ice phase function effects must be considered when interpreting the observations. Two different phase functions corresponding to bright and faint clouds are examined in this analysis. OMI observations show maximum frequency and albedo values at 8-10 h local time in the Northern Hemisphere, with decreasing amplitude at higher latitudes. Southern Hemisphere values reach a minimum at 18-20 h LT. Larger variations are seen in Northern Hemisphere data. No statistically significant longitudinal dependence was seen.

  11. Spectroscopic observations of spatial and temporal variations on Venus

    Science.gov (United States)

    Young, A. T.; Young, L. G.; Woszczyk, A.

    1974-01-01

    Details of the Table Mountain spectroscopic patrol of Venus in September-October 1972 are given. The data indicate systematic variation over the disc, with more CO2 absorption near the terminator than at the limb, and slightly more in the southern than in the northern hemisphere. The semiregular four-day variation, reported to occur simultaneously over the disk at 8689 A by Young et al. (1973), is confirmed by observations of the 7820 A and 7883 A CO2 bands.

  12. 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.

  13. Variation in chemical wet deposition with meteorological conditions

    Science.gov (United States)

    Raynor, Gilbert S.; Hayes, Janet V.

    Analysis of hourly sequential precipitation samples collected at Brookhaven National Laboratory over a 4-y period shows systematic relationships between amounts of chemicals deposited in precipitation and meteorological conditions. Samples were taken by an automatic, sequential sampler and measured for pH, conductivity and the concentrations of major ions. Concurrent measurements and observations were made of the synoptic situation, precipitation type and rate, wind speed and direction, and temperature. Deposition per unit area was computed for subsets of the data classified by meteorological and time parameters. Results demonstrate that precipitation amount alone is not an adequate predictor of chemical wet deposition because of the variability of concentration in precipitation which is a complex function of emission rates and atmospheric processes. Results, however, document those conditions under which most material is deposited and those circumstances in which deposition occurs at the greatest rate. When classified by season, hydrogen and sulfate ion deposition are greatest in the summer when precipitation is lowest and least in the winter when precipitation is greatest. Nitrogen in both nitrate and ammonium has a similar but less extreme pattern. By synoptic type, all chemicals are deposited most heavily in warm front precipitation but the fraction of hydrogen and sulfate deposited in cold front and squall line hours is greater than the fraction of precipitation. All chemicals are deposited most heavily in steady rain when examined by precipitation type but thundershowers deposit chemicals of anthropogenic origin in amounts disproportionate to precipitation amounts. Results are also presented from data classified by other parameters.

  14. 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.

  15. Hydrology Induced Gravity Variation Observed at Vienna and Conrad Observatory

    Science.gov (United States)

    Mikolaj, Michal; Meurers, Bruno

    2013-04-01

    Mass transport associated with hydrological processes induces gravity variations observed by superconducting gravimeter (SG) and thus can mask essential geodynamical signals. The presented study analyses time series acquired by superconducting gravimeter GWR C025 with a focus on hydrological effects. This gravimeter was transported from Vienna to Conrad Observatory in the end of year 2007. The gravimeter was in both cases installed in an underground laboratory, but Conrad Observatory is located in a mountain area, while Vienna represents an urbanized area. This affords an opportunity to study the hydrological gravity response for two different environments. Several global hydrological models are used to estimate the contribution of global hydrology to gravity variations. Local hydrology is analysed using in-situ meteorological measurements. Significant influence of heavy rain on gravity is observed for both underground stations. The gravity variation observed at Conrad Observatory is additionally strongly affected by snow accumulation and melting phase. The SG installation in an underground laboratory together with a specific topographic situation at the place of observation may lead to an interference of local and global hydrological effect.

  16. Chemical Observations of a Polar Vortex Intrusion

    Science.gov (United States)

    Schoeberl, M. R.; Kawa, S. R.; Douglass, A. R.; McGee, T. J.; Browell, E.; Waters, J.; Livesey, N.; Read, W.; Froidevaux, L.

    2006-01-01

    An intrusion of vortex edge air in D the interior of the Arctic polar vortex was observed on the January 31,2005 flight of the NASA DC-8 aircraft. This intrusion was identified as anomalously high values of ozone by the AROTAL and DIAL lidars. Our analysis shows that this intrusion formed when a blocking feature near Iceland collapsed, allowing edge air to sweep into the vortex interior. along the DC-8 flight track also shows the intrusion in both ozone and HNO3. Polar Stratospheric Clouds (PSCs) were observed by the DIAL lidar on the DC-8. The spatial variability of the PSCs can be explained using MLS HNO3 and H2O observations and meteorological analysis temperatures. We also estimate vortex denitrification using the relationship between N2O and HNO3. Reverse domain fill back trajectory calculations are used to focus on the features in the MLS data. The trajectory results improve the agreement between lidar measured ozone and MLS ozone and also improve the agreement between the HNO3 measurements PSC locations. The back trajectory calculations allow us to compute the local denitrification rate and reduction of HCl within the filament. We estimate a denitrification rate of about lO%/day after exposure to below PSC formation temperature. Analysis of Aura MLS observations made

  17. Observations of time variation in the sun's rotation

    Science.gov (United States)

    Woodard, M. F.; Libbrecht, K. G.

    1993-01-01

    Observations of solar p-mode frequency splittings obtained at Big Bear Solar Observatory in 1986 and during 1988-90 reveal small (about 1 percent) changes in the sun's subsurface angular velocity with solar cycle. An asymptotic inversion of the splitting data yields the latitude dependence of the rotation rate and shows that the largest changes in the angular velocity, about 4 nanoHz, occurred between 1986 and the later years, at high (about 60 deg) solar latitudes. Earlier helioseismic observations suggest that solar cycle changes in the ratio of magnetic to turbulent pressure in the solar convection zone are large enough to account for the magnitude of the observed angular velocity variations, but a detailed model of the phenomenon does not exist.

  18. 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...

  19. Evolution of polymer photovoltaic performances from subtle chemical structure variations.

    Science.gov (United States)

    Yan, Han; Li, Denghua; Lu, Kun; Zhu, Xiangwei; Zhang, Yajie; Yang, Yanlian; Wei, Zhixiang

    2012-11-21

    Conjugated polymers are promising replacements for their inorganic counterparts in photovoltaics due to their low cost, ease of processing, and straightforward thin film formation. New materials have been able to improve the power conversion efficiency of photovoltaic cells up to 8%. However, rules for rational material design are still lacking, and subtle chemical structure variations usually result in large performance discrepancies. The present paper reports a detailed study on the crystalline structure, morphology, and in situ optoelectronic properties of blend films of polythiophene derivatives and [6,6]-phenyl C61-butyric acid methyl ester by changing the alkyl side chain length and position of polythiophene. The correlation among the molecular structure, mesoscopic morphology, mesoscopic optoelectronic property and macroscopic device performance (highest efficiency above 4%) was directly established. Both solubility and intermolecular interactions should be considered in rational molecular design. Knowledge obtained from this study can aid the selection of appropriate processing conditions that improve blend film morphology, charge transport property, and overall solar cell efficiency.

  20. 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.

  1. Observer variation in vascular CT measurements of the abdominal aorta

    Energy Technology Data Exchange (ETDEWEB)

    England, Andrew [Department of Radiology, South Manchester University Hospitals NHS Trust, Southmoor Road, Manchester M23 9LT (United Kingdom); Department of Medical Imaging and Radiotherapy, University of Liverpool, Johnson Building, Quadrangle, Brownlow Hill, Liverpool L69 3GB (United Kingdom)], E-mail: a.england@liverpool.ac.uk; Butterfield, John S.; Ashleigh, Raymond J. [Department of Radiology, South Manchester University Hospitals NHS Trust, Southmoor Road, Manchester M23 9LT (United Kingdom)

    2008-11-15

    Aim: To assess the inter-observer variation between a radiographer and radiologist when performing CT measurement of the abdominal aorta before endovascular aortic aneurysm repair (EVAR). Methods: A total of 30 consecutive patients who were considered anatomically suitable for EVAR had aortic measurements performed independently by a vascular radioogist and then by a radiographer training vascular and CT imaging. All measurements were performed on a computer workstation using electronic callipers, each patient had 12 anatomical sites evaluated (eight diameters, four vessel lengths). Statistical analysis was performed by the computer package SPSS for Windows 11.01. Results: Of the 30 patients, mean difference in measurements between observers was 2.3 mm {+-} 1.2 mm and 6.0 mm {+-} 6.4 mm for diameter and vessel length measurements, respectively. Two hundred and seven (86%) diameter measurements were {<=}2 mm of each other and 233 (97%) were within {<=}5 mm. Eighty-two (57%) length measurements were within {<=}5 mm, and 100 (83%) within 10 mm or less. Widest variation existed for measurements of common iliac diameter and aortic neck length, where coefficients of variance were 38.2 (95% CI 35.7-41.0) and 40.0 (95% CI 36.2-44.6), respectively. Conclusion: A good level of agreement exists between a trained radiographer and radiologist when comparing vascular CT measurements of the aorta. It is technically feasible for a radiographer to perform these measurements, and improvements in variability may be achieved from a more standardised technique and automated vessel analysis software. Further research is required to establish the overall variability between different observer types when undertaking vascular CT measurements.

  2. Observations of chemical differentiation in clumpy molecular clouds

    CERN Document Server

    Buckle, J V; Wirström, E S; Charnley, S B; Markwick-Kemper, A J; Butner, H M; Takakuwa, S

    2006-01-01

    We have extensively mapped a sample of dense molecular clouds (L1512, TMC-1C, L1262, Per 7, L1389, L1251E) in lines of HC3N, CH3OH, SO and C^{18}O. We demonstrate that a high degree of chemical differentiation is present in all of the observed clouds. We analyse the molecular maps for each cloud, demonstrating a systematic chemical differentiation across the sample, which we relate to the evolutionary state of the cloud. We relate our observations to the cloud physical, kinematical and evolutionary properties, and also compare them to the predictions of simple chemical models. The implications of this work for understanding the origin of the clumpy structures and chemical differentiation observed in dense clouds are discussed.

  3. 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...

  4. 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...

  5. Observations on variational and projector Monte Carlo methods.

    Science.gov (United States)

    Umrigar, C J

    2015-10-28

    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.

  6. Seasonal variations of Mercury's magnesium dayside exosphere from MESSENGER observations

    Science.gov (United States)

    Merkel, Aimee W.; Cassidy, Timothy A.; Vervack, Ronald J.; McClintock, William E.; Sarantos, Menelaos; Burger, Matthew H.; Killen, Rosemary M.

    2017-01-01

    The Ultraviolet and Visible Spectrometer channel of the Mercury Atmospheric and Surface Composition Spectrometer instrument aboard the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft made near-daily observations of solar-scattered resonant emission from magnesium in Mercury's exosphere during the mission's orbital phase (March 2011-April 2015, ∼17 Mercury years). In this paper, a subset of these data (March 2013-April 2015) is described and analyzed to illustrate Mg's spatial and temporal variations. Dayside altitude profiles of emission are used to make estimates of the Mg density and temperature. The main characteristics of the Mg exosphere are (a) a predominant enhancement of emission in the morning (6 am-10 am) near perihelion, (b) a bulk temperature of ∼6000 K, consistent with impact vaporization as the predominant ejection process, (c) a near-surface density that varies from 5 cm-3 to 50 cm-3 and (d) a production rate that is strongest in the morning on the inbound leg of Mercury's orbit with rates ranging from 1 × 105 cm-2 s-1 to 8 × 105 cm-2 s-1.

  7. Seasonal Variations of Mercury's Magnesium Dayside Exosphere from MESSENGER Observations

    Science.gov (United States)

    Merkel, Aimee W.; Cassidy, Timothy A.; Vervack, Ronald J., Jr.; McClintock, William E.; Sarantos, Menelaos; Burger, Matthew H.; Killen, Rosemary M.

    2017-01-01

    The Ultraviolet and Visible Spectrometer channel of the Mercury Atmospheric and Surface Composition Spectrometer instrument aboard the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft made near-daily observations of solar-scattered resonant emission from magnesium in Mercury's exosphere during the mission's orbital phase (March 2011-April 2015, approx.17 Mercury years). In this paper, a subset of these data (March 2013-April 2015) is described and analyzed to illustrate Mg's spatial and temporal variations. Dayside altitude profiles of emission are used to make estimates of the Mg density and temperature. The main characteristics of the Mg exosphere are (a) a predominant enhancement of emission in the morning (6 am-10 am) near perihelion, (b) a bulk temperature of approx. 6000 K, consistent with impact vaporization as the predominant ejection process, (c) a near-surface density that varies from 5/cu cm to 50/cu cm and (d) a production rate that is strongest in the morning on the inbound leg of Mercury's orbit with rates ranging from 1×10(exp 5)/sq cm/s to 8×10(exp 5)/sq cm/s.

  8. Chemical Variations in a Granitic Pluton and Its Surrounding Rocks.

    Science.gov (United States)

    Baird, A K; McIntyre, D B; Welday, E E; Madlem, K W

    1964-10-09

    New techniques of x-ray fluorescence spectrography have provided, for the first time, abundant data regarding chemical variability of granitic rocks on different scales. The results suggest that current designs of sampling plans for trend surface analysis should be modified; in particular several specimens, preferably drillcores, may be required at each locality.

  9. 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...

  10. 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.

  11. Variation of the Fundamental Constants:. Theory and Observations

    Science.gov (United States)

    Flambaum, V. V.

    2007-10-01

    Review of recent works devoted to the variation of the fine structure constant α, strong interaction and fundamental masses (Higgs vacuum) is presented. The results from Big Bang nucleosynthesis, quasar absorption spectra, and Oklo natural nuclear reactor data give us the space-time variation on the Universe lifetime scale. Comparison of different atomic clocks gives us the present time variation. Assuming linear variation with time we can compare different results. The best limit on the variation of the electron-to-proton mass ratio μ = me/Mp and Xe = me/ΛQCD follows from the quasar absorption spectra:1 ˙ {μ }/μ = ˙ {X}e/X_e = (1 ± 3) × 10-16 yr-1. A combination of this result and the atomic clock results2,3 gives the best limt on variation of α : ˙ {α }/α = (-0.8 ± 0.8) × 10-16 yr-1. The Oklo natural reactor gives the best limit on the variation of Xs = ms/ΛQCD where ms is the strange quark mass:4,5 ∣ ˙ {X}s/X_s∣ < 10-18 yr-1. Note that the Oklo data can not give us any limit on the variation of a since the effect of α there is much smaller than the effect of Xs and should be neglected. Huge enhancement of the relative variation effects happens in transitions between close atomic, molecular and nuclear energy levels. We suggest several new cases where the levels are very narrow. Large enhancement of the variation effects is also possible in cold atomic and molecular collisions near Feshbach resonance. How changing physical constants and violation of local position invariance may occur? Light scalar fields very naturally appear in modern cosmological models, affecting parameters of the Standard Model (e.g. α). Cosmological variations of these scalar fields should occur because of drastic changes of matter composition in Universe: the latest such event is rather recent (about 5 billion years ago), from matter to dark energy domination. Massive bodies (stars or galaxies) can also affect physical constants. They have large scalar charge S

  12. 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.

  13. Large observer variation of clinical assessment of dyspnoeic wheezing children

    NARCIS (Netherlands)

    Bekhof, Jolita; Reimink, Roelien; Bartels, Ine-Marije; Eggink, Hendriekje; Brand, Paul L. P.

    2015-01-01

    Background In children with acute dyspnoea, the assessment of severity of dyspnoea and response to treatment is often performed by different professionals, implying that knowledge of the interobserver variation of this clinical assessment is important. Objective To determine intraobserver and intero

  14. 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.

  15. 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...

  16. Trends and Scales of Observed Soil Moisture Variations in China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new soil moisture dataset from direct gravimetric measurements within the top 50-cm soil layers at 178 soil moisture stations in China covering the period 1981 1998 are used to study the long-term and seasonal trends of soil moisture variations, as well as estimate the temporal and spatial scales of soil moisture for different soil layers. Additional datasets of precipitation and temperature difference between land surface and air (TDSA) are analyzed to gain further insight into the changes of soil moisture. There are increasing trends for the top 10 cm, but decreasing trends for the top 50 cm of soil layers in most regions. Trends in precipitation appear to dominantly influence trends in soil moisture in both cases. Seasonal variation of soil moisture is mainly controlled by precipitation and evaporation, and in some regions can be affected by snow cover in winter. Timescales of soil moisture variation are roughly 1-3 months and increase with soil depth.Further influences of TDSA and precipitation on soil moisture in surface layers, rather than in deeper layers,cause this phenomenon. Seasonal variations of temporal scales for soil moisture are region-dependent and consistent in both layer depths. Spatial scales of soil moisture range from 200-600 km, with topography also having an affect on these. Spatial scales of soil moisture in plains are larger than in mountainous areas. In the former, the spatial scale of soil moisture follows the spatial patterns of precipitation and evaporation,whereas in the latter, the spatial scale is controlled by topography.

  17. 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

  18. Studies of Trace Gas Chemical Cycles Using Observations, Inverse Methods and Global Chemical Transport Models

    Science.gov (United States)

    Prinn, Ronald G.

    2001-01-01

    For interpreting observational data, and in particular for use in inverse methods, accurate and realistic chemical transport models are essential. Toward this end we have, in recent years, helped develop and utilize a number of three-dimensional models including the Model for Atmospheric Transport and Chemistry (MATCH).

  19. Multiple trajectory analysis of MLS observed stratospheric chemical ozone loss in Arctic winter 1995/96

    Science.gov (United States)

    Lemmen, C.; Riese, R.; Grooss, J.-U.; Mueller, R.

    2003-04-01

    Daily ozone loss rates and total chemical ozone depletion during Arctic winter 1995/96 were evaluated based on ozone measurements by the Microwave Limb Sounder (MLS) instrument onboard the Upper Atmosphere Research Satellite (UARS). Employing the 3-dimensional transport scheme of the Chemical Lagrangian Model of the Stratosphere (CLaMS), trajectories from successive satellite measurements were compared with each other using a variation of the Match technique, such that ozone concentration differences between double sounded (``matched'') air parcels represent chemical ozone loss. The ensemble average of many (typically 30--150) matches yields an average ozone depletion rate for the area covered by the trajectories. Total ozone loss from late December to early March was 1.4 ppmv at the 475 K isentropic level within the vortex core (PV > 45 PVU at 475 K). Ozone loss decreased towards the edge of the vortex, no significant ozone loss could be observed in the outer vortex edge (between ≈ 27 and ≈ 35 PVU). Daily ozone loss was found to average 10 ppbv/day throughout January and throughout the extended vortex area. For the month of February daily ozone loss rates were highly variable and peaked at 40 ppbv/day in the vortex (≈ 35 PVU). In this study, no chemical ozone loss could be observed in the outer vortex edge region during February, which suggests that the dynamically defined vortex boundary separated two different chemical regimes during February, but not in January.

  20. 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.

  1. Chemical composition, antioxidant and antimicrobial activities of basil (Ocimum basilicum) essential oils depends on seasonal variations.

    Science.gov (United States)

    Hussain, Abdullah Ijaz; Anwar, Farooq; Hussain Sherazi, Syed Tufail; Przybylski, Roman

    2008-06-01

    Chemical composition, antioxidant and antimicrobial activities of the essential oils from aerial parts of basil (Ocimum basilicum L.) as affected by four seasonal, namely summer, autumn, winter and spring growing variation were investigated. The hydro-distilled essential oils content ranged from 0.5% to 0.8%, the maximum amounts were observed in winter while minimum in summer. The essential oils consisted of linalool as the most abundant component (56.7-60.6%), followed by epi-α-cadinol (8.6-11.4%), α-bergamotene (7.4-9.2%) and γ-cadinene (3.2-5.4%). Samples collected in winter were found to be richer in oxygenated monoterpenes (68.9%), while those of summer were higher in sesquiterpene hydrocarbons (24.3%). The contents of most of the chemical constituents varied significantly (pMucor mucedo, Fusarium solani, Botryodiplodia theobromae, Rhizopus solani was assessed by disc diffusion method and measurement of determination of minimum inhibitory concentration. The results of antimicrobial assays indicated that all the tested microorganisms were affected. Both the antioxidant and antimicrobial activities of the oils varied significantly (p<0.05), as seasons changed.

  2. Observing and understanding the Earth system variations from space geodesy

    OpenAIRE

    Jin, Shuanggen; van Dam, Tonie; Wdowinski, Shimon

    2013-01-01

    The interaction and coupling of the Earth system components that include the atmosphere, hydrosphere, cryosphere, lithosphere, and other fluids in Earth's interior, influence the Earth's shape, gravity field and its rotation (the three pillars of geodesy). The effects of global climate change, such as sea level rise, glacier melting, and geoharzards, also affect these observables. However, observations and models of Earth's system change have large uncertainties due to the lack of direct high...

  3. 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.

  4. 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.

  5. [Nictemeral variation of physical and chemical variables in the Paticos wetland, Ayapel swamp complex, Colombia].

    Science.gov (United States)

    Montoya M, Yimmy; Aguirre R, Néstor

    2009-09-01

    The nictemeral variation of abiotic factors in a key factor for tropical organisms. We evaluated some climatic, physical and chemical variables during four surveys of the hydrologic cycle in the Paticos wetland (8 degrees 21'08.2" N, 75 degrees 08'45.7" W). Of climatic variables, pluviosity presented the highest variation (C.V. = 1 022%) followed by air temperature (C.V. = 19.7%). There was a high relation in the coefficients of variation for these variables (84:1). This relation may be associated with altitude. Throughout the day-night cycle, most variables presented significant differences; except for pluviosity, air and water temperature (because of their high variability). Variables most related with nictemeral variation were pluviosity, wind speed and direction, air temperature and dissolved oxygen.

  6. Observation operator for the assimilation of aerosol type resolving satellite measurements into a chemical transport model

    Directory of Open Access Journals (Sweden)

    M. Schroedter-Homscheidt

    2010-11-01

    Full Text Available Modelling of aerosol particles with chemical transport models is still based mainly on static emission databases while episodic emissions cannot be treated sufficiently. To overcome this situation, a coupling of chemical mass concentration modelling with satellite-based measurements relying on physical and optical principles has been developed. This study deals with the observation operator for a component-wise assimilation of satellite measurements. It treats aerosol particles classified into water soluble, water insoluble, soot, sea salt and mineral dust containing aerosol particles in the atmospheric boundary layer as separately assimilated aerosol components. It builds on a mapping of aerosol classes used both in observation and model space taking their optical and chemical properties into account. Refractive indices for primary organic carbon particles, anthropogenic particles, and secondary organic species have been defined based on a literature review. Together with a treatment of different size distributions in observations and model state, this allows transforming the background from mass concentrations into aerosol optical depths. A two-dimensional, variational assimilation is applied for component-wise aerosol optical depths. Error covariance matrices are defined based on a validation against AERONET sun photometer measurements. Analysis fields are assessed threefold: (1 through validation against AERONET especially in Saharan dust outbreak situations, (2 through comparison with the British Black Smoke and Sulphur Dioxide Network for soot-containing particles, and (3 through comparison with measurements of the water soluble components SO4, NH4, and NO3 conducted by the EMEP (European Monitoring and Evaluation Programme network. Separately, for the water soluble, the soot and the mineral dust aerosol components a bias reduction and subsequent a root mean square error reduction is observed in the

  7. Fusion of chemical, biological, and meteorological observations for agent source term estimation and hazard refinement

    Science.gov (United States)

    Bieringer, Paul E.; Rodriguez, Luna M.; Sykes, Ian; Hurst, Jonathan; Vandenberghe, Francois; Weil, Jeffrey; Bieberbach, George, Jr.; Parker, Steve; Cabell, Ryan

    2011-05-01

    Chemical and biological (CB) agent detection and effective use of these observations in hazard assessment models are key elements of our nation's CB defense program that seeks to ensure that Department of Defense (DoD) operations are minimally affected by a CB attack. Accurate hazard assessments rely heavily on the source term parameters necessary to characterize the release in the transport and dispersion (T&D) simulation. Unfortunately, these source parameters are often not known and based on rudimentary assumptions. In this presentation we describe an algorithm that utilizes variational data assimilation techniques to fuse CB and meteorological observations to characterize agent release source parameters and provide a refined hazard assessment. The underlying algorithm consists of a combination of modeling systems, including the Second order Closure Integrated PUFF model (SCIPUFF), its corresponding Source Term Estimation (STE) model, a hybrid Lagrangian-Eulerian Plume Model (LEPM), its formal adjoint, and the software infrastructure necessary to link them. SCIPUFF and its STE model are used to calculate a "first guess" source estimate. The LEPM and corresponding adjoint are then used to iteratively refine this release source estimate using variational data assimilation techniques. This algorithm has undergone preliminary testing using virtual "single realization" plume release data sets from the Virtual THreat Response Emulation and Analysis Testbed (VTHREAT) and data from the FUSION Field Trials 2007 (FFT07). The end-to-end prototype of this system that has been developed to illustrate its use within the United States (US) Joint Effects Model (JEM) will be demonstrated.

  8. 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.

  9. 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.

  10. 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.

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

    CERN Document Server

    Tosi, M P

    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.

  12. 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

  13. Functional diversity of non-lethal effects, chemical camouflage, and variation in fish avoidance in colonizing beetles.

    Science.gov (United States)

    Resetarits, William J; Pintar, Matthew R

    2016-12-01

    Predators play an extremely important role in natural communities. In freshwater systems, fish can dominate sorting both at the colonization and post-colonization stage. Specifically, for many colonizing species, fish can have non-lethal, direct effects that exceed the lethal direct effects of predation. Functionally diverse fish species with a range of predatory capabilities have previously been observed to elicit functionally equivalent responses on oviposition in tree frogs. We tested this hypothesis of functional equivalence of non-lethal effects for four predatory fish species, using naturally colonizing populations of aquatic beetles. Among taxa other than mosquitoes, and with the exception of the chemically camouflaged pirate perch, Aphredoderus sayanus, we provide the first evidence of variation in colonization or oviposition responses to different fish species. Focusing on total abundance, Fundulus chrysotus, a gape-limited, surface-feeding fish, elicited unique responses among colonizing Hydrophilidae, with the exception of the smallest and most abundant taxa, Paracymus, while Dytiscidae responded similarly to all avoided fish. Neither family responded to A. sayanus. Analysis of species richness and multivariate characterization of the beetle assemblages for the four fish species and controls revealed additional variation among the three avoided species and confirmed that chemical camouflage in A. sayanus results in assemblages essentially identical to fishless controls. The origin of this variation in beetle responses to different fish is unknown, but may involve variation in cue sensitivity, different behavioral algorithms, or differential responses to species-specific fish cues. The identity of fish species occupying aquatic habitats is crucial to understanding community structure, as varying strengths of lethal and non-lethal effects, as well as their interaction, create complex landscapes of predator effects and challenge the notion of functional

  14. Cytotoxicity and chromosome aberrations in normal human oral keratinocytes induced by chemical carcinogens: Comparison of inter-individual variations.

    Science.gov (United States)

    Tsutsui, T; Kawamoto, Y; Suzuki, N; Gladen, B C; Barrett, J C

    1991-01-01

    Normal human keratinocytes from the oral cavity were cultured in vitro in serum-free medium. Cultures from different individuals were established, and the responses of the cells to different chemicals were compared. The cells, grown at clonal densities, were treated separately with an alkylating agent (N-methyl-N'-nitro-N-nitrosoguanidine; MNNG), two arsenical salts (sodium arsenate or sodium arsenite), sodium fluoride or two polyaromatic hydrocarbons (benzo[a]pyrene or 7,12-dimethylbenz[a]-anthracene). There were no significant differences in the colony-forming efficiencies (22.8 +/- 4.2%) of control (untreated) cells from five different individuals. At selected doses, each of the chemicals reduced the colony-forming efficiencies of the treated cells. The cytotoxicity of most of the chemicals did not differ significantly among cells derived from different individuals, with the exception of sodium arsenate at two doses and sodium fluoride at the highest dose tested. Induction of chromosome aberrations by MNNG, sodium arsenite, sodium arsenate and sodium flouride was analysed with cells derived from up to nine individuals. There was little difference in the inducibilities of chromosome aberrations among cultured keratinocytes from different donors. Treatment of cells from nine donors with one dose of sodium fluoride revealed a statistically significant inter-individual variation. These findings provide a model system to study the effects of carcinogens on the target cells for oral cancers. The results can be compared with findings for cells from other epithelial tissues, since the culture conditions support the growth of keratinocytes regardless of origin. Little inter-individual variation was observed in the response of oral keratinocytes to the chemicals examined.

  15. 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

  16. Intrinsic Charge Trapping Observed as Surface Potential Variations in diF-TES-ADT Films.

    Science.gov (United States)

    Hoffman, Benjamin C; McAfee, Terry; Conrad, Brad R; Loth, Marsha A; Anthony, John E; Ade, Harald W; Dougherty, Daniel B

    2016-08-24

    Spatial variations in surface potential are measured with Kelvin probe force microscopy for thin films of 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophenes (diF-TES-ADT) grown on SiO2 and silane-treated SiO2 substrates by organic molecular beam deposition. The variations are observed both between and within grains of the polycrystalline organic film and are quantitatively different than electrostatic variations on the substrate surfaces. The skewness of surface potential distributions is larger on SiO2 than on HMDS-treated substrates. This observation is attributed to the impact of substrate functionalization on minimizing intrinsic crystallographic defects in the organic film that can trap charge.

  17. Observational Evidence for Variations of the Acoustic Cutoff Frequency with Height in the Solar Atmosphere

    Science.gov (United States)

    Wiśniewska, A.; Musielak, Z. E.; Staiger, J.; Roth, M.

    2016-03-01

    Direct evidence for the existence of an acoustic cutoff frequency in the solar atmosphere is given by observations performed by using the HELioseismological Large Regions Interferometric DEvice operating on the Vacuum Tower Telescope located on Tenerife. The observational results demonstrate variations of the cutoff with atmospheric heights. The observed variations of the cutoff are compared to theoretical predictions made by using five acoustic cutoff frequencies that have been commonly used in helioseismology and asteroseismology. The comparison shows that none of the theoretical predictions is fully consistent with the observational data. The implication of this finding is far reaching as it urgently requires either major revisions of the existing methods of finding acoustic cutoff frequencies or developing new methods that would much better account for the physical picture underlying the concept of cutoff frequencies in inhomogeneous media.

  18. 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…

  19. Molecular Origin of Color Variation in Firefly (Beetle) Bioluminescence: A Chemical Basis for Biological Imaging.

    Science.gov (United States)

    Hirano, Takashi

    2016-01-01

    Firefly shows bioluminescence by "luciferin-luciferase" (L-L) reaction using luciferin, luciferase, ATP and O2. The chemical photon generation by an enzymatic reaction is widely utilized for analytical methods including biological imaging in the life science fields. To expand photondetecting analyses with firefly bioluminescence, it is important for users to understand the chemical basis of the L-L reaction. In particular, the emission color variation of the L-L reaction is one of the distinguishing characteristics for multicolor luciferase assay and in vivo imaging. From the viewpoint of fundamental chemistry, this review explains the recent progress in the studies on the molecular mechanism of emission color variation after showing the outline of the reaction mechanism of the whole L-L reaction. On the basis of the mechanism, the progresses in organic synthesis of luciferin analogs modulating their emission colors are also presented to support further developments of red/near infrared in vivo biological imaging utility of firefly bioluminescence.

  20. Causes of Observed Long-Periodic Variations of the Polarization at Polar Regions of Jupiter

    CERN Document Server

    Shalygina, O S; Shalygin, E V; Marchenko, G P; Velikodsky, Y I; Akimov, L A; Starodubtseva, O M; Velikodsky, Yu. I.

    2006-01-01

    Data of 23-years of Jupiter polarimetric observations (1981- 2004) have been reprocessed using new improved technique. The data from other observers have been added to the analysis (1971-74). Anticorrelation between asymmetry of polarization and insolation has been found. The mechanism of influence of seasons changing (through temperature variations) on north-south asymmetry of polarization formation has been proposed. Also a possibility of existence of influence of solar cosmic rays flux on polarization value is noted.

  1. 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

  2. Modeling the Jovian magnetic field and its secular variation using all available magnetic field observations

    Science.gov (United States)

    Ridley, Victoria A.; Holme, Richard

    2016-03-01

    We present new models of Jupiter's internal magnetic field and secular variation from all available direct measurements from three decades of spacecraft observation. A regularized minimum norm approach allows the creation of smooth, numerically stable models displaying a high degree of structure. External field from the magnetodisk is modeled iteratively for each orbit. Jupiter's inner magnetosphere is highly stable with time, with no evidence for variation with solar activity. We compare two spherical harmonic models, one assuming a field constant in time and a second allowing for linear time variation. Including secular variation improves data fit with fewer additional parameters than increasing field complexity. Our favored solution indicates a ˜0.012% yr-1 increase in Jupiter's dipole magnetic moment from 1973 to 2003; this value is roughly one quarter of that for Earth. Inaccuracies in determination of the planetary reference frame cannot explain all the observed secular variation. Should more structure be allowed in the solutions, we find the northern hemispherical configuration resembles recent models based on satellite auroral footprint locations, and there is also evidence of a possible patch of reversed polar flux seen at the expected depth of the dynamo region, resembling that found at Earth and with implications for the Jovian interior. Finally, using our preferred model, we infer flow dynamics at the top of Jupiter's dynamo source. Though highly speculative, the results produce several gyres with some symmetry about the equator, similar to those seen at Earth's core-mantle boundary, suggesting motion on cylinders aligned with the rotation axis.

  3. 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.

  4. Observed variations of methane on Mars unexplained by known atmospheric chemistry and physics.

    Science.gov (United States)

    Lefèvre, Franck; Forget, François

    2009-08-06

    The detection of methane on Mars has revived the possibility of past or extant life on this planet, despite the fact that an abiogenic origin is thought to be equally plausible. An intriguing aspect of the recent observations of methane on Mars is that methane concentrations appear to be locally enhanced and change with the seasons. However, methane has a photochemical lifetime of several centuries, and is therefore expected to have a spatially uniform distribution on the planet. Here we use a global climate model of Mars with coupled chemistry to examine the implications of the recently observed variations of Martian methane for our understanding of the chemistry of methane. We find that photochemistry as currently understood does not produce measurable variations in methane concentrations, even in the case of a current, local and episodic methane release. In contrast, we find that the condensation-sublimation cycle of Mars' carbon dioxide atmosphere can generate large-scale methane variations differing from those observed. In order to reproduce local methane enhancements similar to those recently reported, we show that an atmospheric lifetime of less than 200 days is necessary, even if a local source of methane is only active around the time of the observation itself. This implies an unidentified methane loss process that is 600 times faster than predicted by standard photochemistry. The existence of such a fast loss in the Martian atmosphere is difficult to reconcile with the observed distribution of other trace gas species. In the case of a destruction mechanism only active at the surface of Mars, destruction of methane must occur with an even shorter timescale of the order of approximately 1 hour to explain the observations. If recent observations of spatial and temporal variations of methane are confirmed, this would suggest an extraordinarily harsh environment for the survival of organics on the planet.

  5. 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.

  6. 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.

  7. Chemical Cartography in the Milky Way with SDSS/APOGEE: Multi-element abundances and abundance ratio variations

    Science.gov (United States)

    Holtzman, Jon A.; Hasselquist, Sten; Johnson, Jennifer; Bird, Jonathan C.; Majewski, Steven R.; SDSS/APOGEE Team

    2017-01-01

    The SDSS/APOGEE project is measuring abundances of multiple elements for several hundred thousand stars across the Milky Way. These allow the mapping of abundances and abundance ratio variations. Results will be presented for multiple abundance ratios across of the Galactic disk. The interpretation of mean abundance maps is complicated by variations in star formation history across the disk and by changing abundance ratios that result from an overall metallicity gradient. Variations in chemical abundance sequences, however, show the potential for using abundance ratios to track the movement of stars through the disk, and provide key information for constraining Galaxy formation and chemical evolution models.

  8. 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

  9. The role of genetic and chemical variation of Pinus sylvestris seedlings in influencing slug herbivory.

    Science.gov (United States)

    O'Reilly-Wapstra, Julianne M; Iason, Glenn R; Thoss, Vera

    2007-05-01

    This study investigated the genetic and chemical basis of resistance of Pinus sylvestris seedlings to herbivory by a generalist mollusc, Arion ater. Using feeding trials with captive animals, we examined selective herbivory by A. ater of young P. sylvestris seedlings of different genotypes and correlated preferences with seedling monoterpene levels. We also investigated the feeding responses of A. ater to artificial diets laced with two monoterpenes, Delta(3)-carene and alpha-pinene. Logistic regression indicated that two factors were the best predictors of whether seedlings in the trial would be consumed. Individual slug variation (replicates) was the most significant factor in the model; however, alpha-pinene concentration (also representing beta-pinene, Delta(3)-carene and total monoterpenes due to multicollinearity) of needles was also a significant factor. While A. ater did not select seedlings on the basis of family, seedlings not eaten were significantly higher in levels of alpha-pinene compared to seedlings that were consumed. We also demonstrated significant genetic variation in alpha-pinene concentration of seedlings between different families of P. sylvestris. Nitrogen and three morphological seedling characteristics (stem length, needle length and stem diameter) also showed significant genetic variation between P. sylvestris families. Artificial diets laced with high (5 mg g(-1) dry matter) quantities of either Delta(3)-carene or alpha-pinene, were eaten significantly less than control diets with no added monoterpenes, supporting the results of the seedling feeding trial. This study demonstrates that A. ater selectively feed on P. sylvestris seedlings and that this selection is based, in part, on the monoterpene concentration of seedlings. These results, coupled with significant genetic variation in alpha-pinene concentration of seedlings and evidence that slug herbivory is detrimental to P. sylvestris fitness, are discussed as possible evidence for A

  10. Chemical variation in a dominant tree species: population divergence, selection and genetic stability across environments.

    Directory of Open Access Journals (Sweden)

    Julianne M O'Reilly-Wapstra

    Full Text Available 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, Eucalyptus globulus. Using two common garden trials we examined variation in PSMs at multiple genetic scales; among 12 populations covering the full geographic range of the species and among up to 60 families within populations. Significant genetic variation in the expression of many PSMs resides both among and within populations of E. globulus with moderate (e.g., sideroxylonal A h(2op = 0.24 to high (e.g., macrocarpal G h(2op = 0.48 narrow sense heritabilities and high coefficients of additive genetic variation estimated for some compounds. A comparison of Qst and Fst estimates suggest that variability in some of these traits may be due to selection. Importantly, there was no genetic by environment interaction in the expression of any of the quantitative chemical traits despite often significant site effects. These results provide evidence that natural selection has contributed to population divergence in PSMs in E. globulus, and identifies the formylated phloroglucinol compounds (particularly sideroxylonal and a dominant oil, 1,8-cineole, as candidates for traits whose genetic architecture has been shaped by divergent selection. Additionally, as the genetic differences in these PSMs that influence community phenotypes is stable across environments, the role of plant genotype in structuring communities is strengthened and these genotypic differences may be relatively stable under global environmental changes.

  11. 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.

  12. Active Chemical Sensing With Partially Observable Markov Decision Processes

    Science.gov (United States)

    Gosangi, Rakesh; Gutierrez-Osuna, Ricardo

    2009-05-01

    We present an active-perception strategy to optimize the temperature program of metal-oxide sensors in real time, as the sensor reacts with its environment. We model the problem as a partially observable Markov decision process (POMDP), where actions correspond to measurements at particular temperatures, and the agent is to find a temperature sequence that minimizes the Bayes risk. We validate the method on a binary classification problem with a simulated sensor. Our results show that the method provides a balance between classification rate and sensing costs.

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

    CERN Document Server

    Hernandez-Martinez, Liliana; Peña, Miriam; Peimbert, Manuel

    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 recombination lines (RLs), are used. We try to use our models as a tool to discriminate between both procedures for abundance determinations. In our chemical evolution code, the chemical contribution of low and intermediate mass stars is time delayed, while for the massive stars the chemical contribution follows the instantaneous recycling approximation. Our models have two main free parameters: the mass-loss rate of a well-mixed outflow and the upper mass limit, $M_{up}$, of the initial mass function (IMF). To reproduce the gaseous ...

  14. 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.

  15. 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.

  16. 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.

  17. Variation of Jupiter's aurora observed by Hisaki/EXCEED: 1. Observed characteristics of the auroral electron energies compared with observations performed using HST/STIS

    Science.gov (United States)

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

    2016-05-01

    Temporal variation of Jupiter's northern aurora is detected using the Extreme Ultraviolet Spectroscope for Exospheric Dynamics (EXCEED) on board JAXA's Earth-orbiting planetary space telescope Hisaki. The wavelength coverage of EXCEED includes the H2 Lyman and Werner bands at 80-148 nm from the entire northern polar region. The prominent periodic modulation of the observed emission corresponds to the rotation of Jupiter's main auroral oval through the aperture, with additional superposed -50%-100% temporal variations. The hydrocarbon color ratio (CR) adopted for the wavelength range of EXCEED is defined as the ratio of the emission intensity in the long wavelength range of 138.5-144.8 nm to that in the short wavelength range of 126.3-130 nm. This CR varies with the planetary rotation phase. Short- (within one planetary rotation) and long-term (> one planetary rotation) enhancements of the auroral power are observed in both wavelength ranges and result in a small CR variation. The occurrence timing of the auroral power enhancement does not clearly depend on the central meridian longitude. Despite the limitations of the wavelength coverage and the large field of view of the observation, the auroral spectra and CR-brightness distribution measured using EXCEED are consistent with other observations.

  18. Direct estimation of tidally induced Earth rotation variations observed by VLBI

    Science.gov (United States)

    Englich, S.; Heinkelmann, R.; BOHM, J.; Schuh, H.

    2009-09-01

    The subject of our study is the investigation of periodical variations induced by solid Earth tides and ocean tides in Earth rotation parameters (ERP: polar motion, UT1)observed by VLBI. There are two strategies to determine the amplitudes and phases of Earth rotation variations from observations of space geodetic techniques. The common way is to derive time series of Earth rotation parameters first and to estimate amplitudes and phases in a second step. Results obtained by this means were shown in previous studies for zonal tidal variations (Englich et al.; 2008a) and variations caused by ocean tides (Englich et al.; 2008b). The alternative method is to estimate the tidal parameters directly within the VLBI data analysis procedure together with other parameters such as station coordinates, tropospheric delays, clocks etc. The purpose of this work was the application of this direct method to a combined VLBI data analysis using the software packages OCCAM (Version 6.1, Gauss-Markov-Model) and DOGSCS (Gerstl et al.; 2001). The theoretical basis and the preparatory steps for the implementation of this approach are presented here.

  19. Regional variation of inner core anisotropy from seismic normal mode observations.

    Science.gov (United States)

    Deuss, Arwen; Irving, Jessica C E; Woodhouse, John H

    2010-05-21

    Earth's solid inner core is surrounded by a convecting liquid outer core, creating the geodynamo driving the planet's magnetic field. Seismic studies using compressional body waves suggest hemispherical variation in the anisotropic structure of the inner core, but are poorly constrained because of limited earthquake and receiver distribution. Here, using normal mode splitting function measurements from large earthquakes, based on extended cross-coupling theory, we observe both regional variations and eastern versus western hemispherical anisotropy in the inner core. The similarity of this pattern with Earth's magnetic field suggests freezing-in of crystal alignment during solidification or texturing by Maxwell stress as origins of the anisotropy. These observations limit the amount of inner core super rotation, but would be consistent with oscillation.

  20. 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.

  1. Mineral and chemical variations within an ash-flow sheet from Aso caldera, Southwestern Japan

    Science.gov (United States)

    Lipman, P.W.

    1967-01-01

    Although products of individual volcanic eruptions, especially voluminous ash-flow eruptions, have been considered among the best available samples of natural magmas, detailed petrographic and chemical study indicates that bulk compositions of unaltered Pleistocene ash-flow tuffs from Aso caldera, Japan, deviate significantly from original magmatic compositions. The last major ash-flow sheet from Aso caldera is as much as 150 meters thick and shows a general vertical compositional change from phenocryst-poor rhyodacite upward into phenocryst-rich trachyandesite; this change apparently reflects in inverse order a compositionally zoned magma chamber in which more silicic magma overlay more mafic magma. Details of these magmatic variations were obscured, however, by: (1) mixing of compositionally distinct batches of magma during upwelling in the vent, as indicated by layering and other heterogeneities within single pumice lumps; (2) mixing of particulate fragments-pumice lumps, ash, and phenocrysts-of varied compositions during emplacement, with the result that separate pumice lenses from a single small outcrop may have a compositional range nearly as great as the bulk-rook variation of the entire sheet; (3) density sorting of phenocrysts and ash during eruption and emplacement, resulting in systematic modal variations with distance from the caldera; (4) addition of xenocrysts, resulting in significant contamination and modification of proportions of crystals in the tuffs; and (5) ground-water leaching of glassy fractions during hydration after cooling. Similar complexities characterize ash-flow tuffs under study in southwestern Nevada and in the San Juan Mountains, Colorado, and probably are widespread in other ash-flow fields as well. Caution and careful planning are required in study of the magmatic chemistry and phenocryst mineralogy of these rocks. ?? 1967 Springer-Verlag.

  2. Observed diurnal variation changes of Jakarta precipitation from 144 available meteorological records

    Science.gov (United States)

    Siswanto, Siswanto; van Oldenborgh, Geert Jan; van den Hurk, Bart; Jilderda, Rudmer

    2013-04-01

    Using a long available meteorological observation for almost 114 years hourly and daily record from Jakarta Observatory, the temporal heterogeneity of climate trends and its variability over Jakarta, Indonesia has been studied. The analyses showed that the number of wet days has decreased between 1880 and 2010, while the precipitation exceeding 50 mm is observed to be slightly increased. An increased trend of heavy rainfall in the 80% and 95% percentile between April and September was detected. Diurnal variation of Jakarta precipitation and temperature changed markedly. In the wet season (DJF), the morning rainfall has increased in intensity, while in other seasons; delayed amplitude of late afternoon rainfall peak is observed. The diurnal variation of night time temperature considerably increased while daytime temperature remains similar. Changes in temporal characteristics of light and heavy precipitation, as well as the diurnal variation of precipitation and temperature lead to hypotheses concerning anthropogenic influence. Some theoretical arguments on Urban Heat Island and aerosol effect precipitation could be linked to our results. Jakarta is a metropolitan city where its development is characterized by mixing of many different land uses and economic activities, including large-scale housing projects, industrial estates, and agricultural activities. In the future, the separation of local response to large scale and local changes will be investigated.

  3. Interannual mass variation over Chao Phraya river basin observed by GRACE

    Science.gov (United States)

    Yamamoto, Keiko; Fukuda, Yoichi; Nakaegawa, Toshiyuki; Hasegawa, Takashi; Taniguchi, Makoto

    2010-05-01

    A project to assess the effects of human activities on the subsurface environment in Asian developing cities has been in progress (Research Institute for Humanity and Nature, Japan, 2009). Bangkok, Thailand is one of the study cities in this project. Using GRACE satellite gravity data of 2002 to 2009, we recovered landwater mass variation over the Chao Phraya river basin, where Bangkok is located on the downstream. The result shows that a negative interannual mass trend was observed over the Chao Phraya river basin from 2002 to the beginning of 2005, and after that, no significant trend was observed up to 2009. Over Bangkok and the surrounding area, serious groundwater decrease has been reported because of the previous excessive pumping accompanying development of the city. One of our concerns is whether the GRACE-derived negative trend from 2002 to 2005 has some relationship with the previous groundwater pumping. Thus, we firstly compared the GRACE-derived mass variation with a groundwater storage variation calculated by a regional numerical groundwater model (Yamanaka, personal communication, 2009). The result shows that the model-estimated confined groundwater storage shows positive interannual trend over the GRACE mission time period, which is in contrast to GRACE-derived negative mass change. Further, the magnitude of the confined groundwater storage change is much smaller than that of the GRACE-derived mass change. Thus, it is expected that the negative mass trend was not caused by regional confined groundwater decrease. On the other hand, the terrestrial water storage variation derived from global scale hydrological model shows similar change with the GRACE-derived mass variation. Further, similar mass trend changes at the beginning of 2005 are observed not only over Chao Phraya basin, but over several other areas in the world, e.g. Africa, Antarctica etc. Thus, we supposed that the negative mass change over Chao Phraya basin does not mainly come from

  4. 4D-Var Assimilation of MIPAS chemical observations: ozone and nitrogen dioxide analyses

    Directory of Open Access Journals (Sweden)

    Q. Errera

    2008-04-01

    Full Text Available This paper discusses the global analyses of stratospheric ozone (O3 and nitrogen dioxide (NO2 obtained by the Belgian Assimilation System for Chemical Observations from Envisat (BASCOE. Based on a chemistry transport model (CTM and the 4-dimensional variational (4D-Var method, BASCOE has assimilated chemical observations of O3, NO2, HNO3, N2O, CH4 and H2O, made between July 2002 and March 2004 by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS onboard the European Space Agency (ESA Environment Satellite (ENVISAT. This corresponds to the entire period during which MIPAS was operating at its nominal resolution.

    Our analyses are evaluated against assimilated MIPAS data and independent HALOE (HALogen Occultation Experiment and POAM-III (Polar Ozone and Aerosol Measurement satellite data. A good agreement is generally found between the analyses and these datasets, in both cases within the estimated error bars of the observations. The benefit of data assimilation is also evaluated using a BASCOE free model run. For O3, the gain from the assimilation is significant during ozone hole conditions, and in the lower stratosphere. Elsewhere, the free model run is within the MIPAS uncertainties and the assimilation does not provide significant improvement. For NO2, the gain from the assimilation is realized through most of the stratosphere. Using the BASCOE analyses, we estimate the differences between MIPAS data and independent data from HALOE and POAM-III, and find results close to those obtained by classical validation methods involving only direct measurement-to-measurement comparisons. Our results extend and reinforce previous MIPAS data validation efforts by taking account of a much larger variety of atmospheric states and measurement conditions.

    This study discusses possible further developments of the

  5. Anomalous ocean load tide signal observed in lake-level variations in Tierra del Fuego

    Science.gov (United States)

    Richter, A.; Hormaechea, J. L.; Dietrich, R.; Perdomo, R.; Fritsche, M.; Del Cogliano, D.; Liebsch, G.; Mendoza, L.

    2009-03-01

    We demonstrate the application of a 100 km long lake as a sensor for studying the tidal effects on Tierra del Fuego main island. The lake-level variations observed in Lago Fagnano reflect both the direct response to the tidal potential and the indirect effect of the ocean tidal loading. Modeling both contributions explains the observed tidal signal in the lake to about 70%. Underestimated model load tide amplitudes are found to be probably responsible for the remaining difference. We interpret this discrepancy as a hint for regional elastic lithosphere properties differing substantially from those represented by currently available global models.

  6. 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.

  7. Lake-level variations of Lago Fagnano, Tierra del Fuego: observations, modelling and interpretation

    Directory of Open Access Journals (Sweden)

    Luciano MENDOZA

    2010-02-01

    Full Text Available The lake-level variations of Lago Fagnano, the largest lake in Tierra del Fuego, southernmost South America, on time scales from a few minutes to three years are investigated using a geodetic approach and applying the tools of time series analysis. Based on pressure tide gauge records at three locations in the lake precise lake-level time series are derived. The analysis of the observed variations in space, time and frequency domain leads to the separation of the principal force-response mechanisms. We show that the lake-level variations in Lago Fagnano can be described essentially as a combination of lake-level shift and tilt and of surface seiches. Regarding the lake-level response to air-pressure forcing, a significant departure from the inverse barometer model is found. Surface seiches dynamics are particularly intensive in Lago Fagnano pointing towards exceptionally low dissipative friction. An undisturbed series of seiches lasting eleven days is presented; and at least eleven longitudinal modes are identified. Based on the characterisation of the main contributions in space and time as well as their relation to the driving forces, a model for the transfer of the lake-level variations at a reference point to an arbitrary location in the lake with an accuracy of 1 cm is developed.

  8. 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.

  9. Spatiotemporal variations of extreme low temperature for emergency transport: a nationwide observational study

    Science.gov (United States)

    Onozuka, Daisuke; Hagihara, Akihito

    2016-12-01

    Although recent studies have investigated the effect of extreme heat on emergency transport, few have investigated the spatiotemporal variations of extreme low temperature for emergency transport on a national scale. Data pertaining to emergency ambulance transport and weather variation in the 47 prefectures of Japan between 2007 and 2010 were obtained. Nonlinear and delayed relationships between temperature and morbidity were assessed using a two-stage analysis. First, a Poisson regression analysis allowing for overdispersion in a distributed lag nonlinear model was used to estimate the prefecture-specific effects of temperature on morbidity. Second, a multivariate meta-analysis was applied to pool estimates on a national level. Of 15,868,086 emergency transports over the study period, 5,375,621 emergency transports were reported during the winter months (November through February). The overall cumulative relative risk (RR) at the first percentile vs. the minimum morbidity percentile was 1.24 (95 % CI = 1.15-1.34) for all causes, 1.50 (95 % CI = 1.30-1.74) for cardiovascular diseases, and 1.59 (95 % CI = 1.33-1.89) for respiratory diseases. There were differences in the temporal variations between extreme low temperature and respiratory disease morbidity. Spatial variation between prefectures was observed for all causes (Cochran Q test, p social and environmental factors, which can be responsible for spatial heterogeneity between prefectures.

  10. 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 (...

  11. 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.

  12. Analysis of Hydrology Induced Gravity Variations Observed by GRACE --- and Other Applications of Spherical Wavelets

    Science.gov (United States)

    Michel, V.

    2005-12-01

    A spherical wavelet analysis of monthly GRACE gravity data is presented. We observe strong correlations to gravity variations predicted by some common hydrology models, in particular in the Amazon, Zambezi and Ganges area. A time series analysis of the predicted gravity due to surface density changes in comparison to spherical wavelet coefficients of the GRACE potential demonstrates the advantages of spherical wavelets. Whereas a spherical harmonics expansion always implicitly includes a global averaging process, wavelets represent localizing basis functions that are much better able to analyze regional variations of a considered data set. Moreover, it is demonstrated that the spherical wavelet approach due to W. Freeden and U. Windheuser can be extended to a larger set of problems including the modelling of functions on balls, i.e. not only on the spherical surface. Examples of applications, such as the volume density recovery from simulated SGG gravity data (cf. planned satellite mission GOCE) are demonstrated. References: M.J. Fengler, W. Freeden, A. Kohlhaas, V. Michel, T. Peters: Wavelet Modelling of Regional and Temporal Variations of the Earth's Gravitational Potential Observed by GRACE, Schriften zur Funktionalanalysis und Geomathematik, 21 (2005), preprint, article submitted to Journal of Geodesy, 2005. V. Michel: Regularized Wavelet--based Multiresolution Recovery of the Harmonic Mass Density Distribution from Data of the Earth's Gravitational Field at Satellite Height, Inverse Problems, 21 (2005), 997-1025.

  13. Airborne Observations of Regional Variations in Fluorescent Aerosol Across the U.S.

    Science.gov (United States)

    Perring, A. E.; Schwarz, J. P.; Baumgardner, D.; Hernandez, M.; Spracklen, D. V.; Heald, C. L.; Gao, R. S.; Kok, G. L.; McMeeking, G.; McQuaid, J. B.; Fahey, D. W.

    2014-12-01

    Airborne observations of fluorescent aerosol were made aboard an airship during CloudLab, a series of flights that took place in September and October of 2013 and covered a wide band of longitude across the continental US between Florida and California between 28 and 37N latitude. Sampling occurred from near the surface to 1000 m above the ground. A Wide-band Integrated Bioaerosol Sensor (WIBS-4) measured concentrations of supermicron fluorescent particles with average regional concentrations ranging from 1.4±0.7 to 6.8±1.4 x 104 particles m-3 and representing up to 24% of total supermicron particle number. We observed distinct variations in size distributions and fluorescent characteristics in different regions, and attribute these to geographically diverse bioaerosol populations. Fluorescent aerosol signatures detected in the east is largely consistent with those of mold spores observed in a laboratory setting. A shift to larger sizes associated with different fluorescent patterns is observed in the west. Loadings in the desert west were nearly as high as those near the Gulf of Mexico, indicating that bioaerosol is a substantial component of supermicron aerosol both of these humid and arid environments. The observations are compared to simulated fungal and bacterial loadings. Good agreement in both particle size and concentrations is observed in the east. In the west the model underestimates observed concentrations by a factor of 2 to 3 and the prescribed particle sizes are smaller than the observed bioaerosol.

  14. 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

  15. Mechanisms of passive tracer interhemispheric transport: An analysis of model-derived and observational interhemispheric transport climatology and interannual variations

    Science.gov (United States)

    Lintner, Benjamin Richard

    2003-10-01

    Examination of the distributions of minor atmospheric constituents may provide valuable insight into atmospheric transport processes. Interhemispheric transport (IHT), the cross-equatorial linkage of the Northern and Southern Hemispheres, is an important aspect of transport that can be explored using the properties of passive tracers. In this dissertation, the principal spatial and temporal features of IHT are examined through modeling and observational approaches. Using the Goddard Institute for Space Studies-University of California, Berkeley (GISS-UCB) atmospheric general circulation model (AGCM) and its companion tracer transplant model (TTM), IHT climatology is first described. Means of assessing IHT, including a simple two-box model and transport partitioning, are introduced, and the seasonality of IHT is elaborated. Particular emphasis is placed upon the elucidation of the longitudinal and vertical features of IHT. IHT sensitivity to source emission geometry and convective mixing is also explored using both the TTM and a Lagrangian trajectory model (LTM) approach. This dissertation further addresses the interannual variability (IAV) of IHT within the GISS-UCB AGCM framework. Analysis of several AGCM simulations, including an ensemble of "Identical Forcing" runs, reveals that IHT IAV is small relative to either the mean IHT timescale or its seasonal variations. IHT IAV is linked to both axisymmetric and regional circulations, and both forced and unforced circulation variations contribute significantly to the development of IHT anomalies. Among the mechanisms that modulate IHT on interannual timescales are changes in the intensity/geometry of the Hadley circulation, variations of the strength/displacement of the zonal-mean and regional Intertropical Convergence Zones (ITCZs), the El Nino/Southern Oscillation (ENSO), and the Indian Ocean Monsoon (IOM). The IOM appears to play an especially prominent role in the modulation of IHT. A comparison of AGCM

  16. 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.

  17. 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.

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

    Science.gov (United States)

    Chien, Yeh-Chung

    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 mug per cubic meter) to thousands of mug 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.

  19. Modelling and optimization of film thickness variation for plasma enhanced chemical vapour deposition processes

    Science.gov (United States)

    Waddell, Ewan; Gibson, Des; Lin, Li; Fu, Xiuhua

    2011-09-01

    This paper describes a method for modelling film thickness variation across the deposition area within plasma enhanced chemical vapour deposition (PECVD) processes. The model enables identification and optimization of film thickness uniformity sensitivities to electrode configuration, temperature, deposition system design and gas flow distribution. PECVD deposition utilizes a co-planar 300mm diameter electrodes with separate RF power matching to each electrode. The system has capability to adjust electrode separation and electrode temperature as parameters to optimize uniformity. Vacuum is achieved using dry pumping with real time control of butterfly valve position for active pressure control. Comparison between theory and experiment is provided for PECVD of diamond-like-carbon (DLC) deposition onto flat and curved substrate geometries. The process utilizes butane reactive feedstock with an argon carrier gas. Radiofrequency plasma is used. Deposited film thickness sensitivities to electrode geometry, plasma power density, pressure and gas flow distribution are demonstrated. Use of modelling to optimise film thickness uniformity is demonstrated. Results show DLC uniformity of 0.30% over a 200 mm flat zone diameter within overall electrode diameter of 300mm. Thickness uniformity of 0.75% is demonstrated over a 200mm diameter for a non-conformal substrate geometry. Use of the modelling method for PECVD using metal-organic chemical vapour deposition (MOCVD) feedstock is demonstrated, specifically for deposition of silica films using metal-organic tetraethoxy-silane. Excellent agreement between experimental and theory is demonstrated for conformal and non-conformal geometries. The model is used to explore scalability of PECVD processes and trade-off against film thickness uniformity. Application to MEMS, optical coatings and thin film photovoltaics is discussed.

  20. 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...

  1. ESTIMATING THE DEEP SOLAR MERIDIONAL CIRCULATION USING MAGNETIC OBSERVATIONS AND A DYNAMO MODEL: A VARIATIONAL APPROACH

    Energy Technology Data Exchange (ETDEWEB)

    Hung, Ching Pui; Jouve, Laurène; Brun, Allan Sacha [Laboratoire AIM Paris-Saclay, CEA/IRFU Université Paris-Diderot CNRS/INSU, F-91191 Gif-Sur-Yvette (France); Fournier, Alexandre [Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot UMR 7154 CNRS, F-75005 Paris (France); Talagrand, Olivier [Laboratoire de météorologie dynamique, UMR 8539, Ecole Normale Supérieure, Paris Cedex 05 (France)

    2015-12-01

    We show how magnetic observations of the Sun can be used in conjunction with an axisymmetric flux-transport solar dynamo model in order to estimate the large-scale meridional circulation throughout the convection zone. Our innovative approach rests on variational data assimilation, whereby the distance between predictions and observations (measured by an objective function) is iteratively minimized by means of an optimization algorithm seeking the meridional flow that best accounts for the data. The minimization is performed using a quasi-Newton technique, which requires knowledge of the sensitivity of the objective function to the meridional flow. That sensitivity is efficiently computed via the integration of the adjoint flux-transport dynamo model. Closed-loop (also known as twin) experiments using synthetic data demonstrate the validity and accuracy of this technique for a variety of meridional flow configurations, ranging from unicellular and equatorially symmetric to multicellular and equatorially asymmetric. In this well-controlled synthetic context, we perform a systematic study of the behavior of our variational approach under different observational configurations by varying their spatial density, temporal density, and noise level, as well as the width of the assimilation window. We find that the method is remarkably robust, leading in most cases to a recovery of the true meridional flow to within better than 1%. These encouraging results are a first step toward using this technique to (i) better constrain the physical processes occurring inside the Sun and (ii) better predict solar activity on decadal timescales.

  2. 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.

  3. 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.

  4. Variation in T-SPOT.TB spot interpretation between independent observers from different laboratories.

    Science.gov (United States)

    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

    2009-10-01

    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-SPOT.TB had been performed with frozen material. Culture plates were read visually by four different observers from two laboratories and by two automated readers. Of 313 T-SPOT.TB assays, 235 were performed with fresh cells and 78 were performed with frozen cells. No significant difference was found between results obtained with fresh cells and those obtained with frozen cells. The percentage of positive results varied between readers by maximally 15%; five/six raters were within a 6% difference in positive results. Analysis of the observed interrater differences showed that some individuals systematically counted more spots than others did. Because test interpretation includes subtraction of background values, this systematic variance had little influence on interindividual differences. The test result as positive or negative varied between independent raters, mainly due to samples with values around the cutoff. This warrants further study regarding determinants affecting the reading of T-SPOT.TB.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. Chemically engineering ligand selectivity at the free fatty acid receptor 2 based on pharmacological variation between species orthologs

    DEFF Research Database (Denmark)

    Hudson, Brian D; Christiansen, Elisabeth; Tikhonova, Irina G

    2012-01-01

    When it is difficult to develop selective ligands within a family of related G-protein-coupled receptors (GPCRs), chemically engineered receptors activated solely by synthetic ligands (RASSLs) are useful alternatives for probing receptor function. In the present work, we explored whether a RASSL...... on this receptor and demonstrates that exploitation of pharmacological variation between species orthologs is a powerful method to generate novel chemically engineered GPCRs.-Hudson, B. D., Christiansen, E., Tikhonova, I. G., Grundmann, M., Kostenis, E., Adams, D. R., Ulven, T., Milligan, G. Chemically engineering...

  10. Phenotypic Variations in the Foliar Chemical Profile of Persea americana Mill. cv. Hass.

    Science.gov (United States)

    García-Rodríguez, Yolanda Magdalena; Torres-Gurrola, Guadalupe; Meléndez-González, Claudio; Espinosa-García, Francisco J

    2016-12-01

    The Hass avocado tree Persea americana cv. Hass was derived from a single hybrid tree of P. americana var. drymifolia and P. americana var. guatemalensis, and it is propagated clonally by grafting. This cultivar is the most widely planted in the world but its profile of secondary metabolites has been studied rarely despite of its importance in plant protection. We illustrate the variability of the volatilome of mature leaves by describing the average chemical composition and the phenotypic variability found in 70 trees. Contrary to the uniformity expected in the Hass cultivar, high variability coefficients were found for most of the 36 detected foliar volatile compounds; furthermore we found six chemotypes grouping the foliar phenotypes of the sampled trees using hierarchical cluster analysis. About 48% of trees were grouped in one chemotype; five chemotypes grouped the remaining trees. The compounds that determined these chemotypes were: estragole, α-farnesene, β-caryophyllene, germacrene D, α-cubebene and eugenol. This striking variation in a cultivar propagated clonally is discussed in terms of somatic mutation.

  11. Salinity variations and chemical compositions of waters in the Frio Formation, Texas Gulf Coast. Annual report

    Energy Technology Data Exchange (ETDEWEB)

    Morton, R.A.; Garrett, C.M. Jr.; Posey, J.S.; Han, J.H.; Jirik, L.A.

    1981-11-01

    Waters produced from sandstone reservoirs of the deep Frio Formation exhibit spatial variations in chemical composition that roughly coincide with the major tectonic elements (Houston and Rio Grande Embayments, San Marcos Arch) and corresponding depositional systems (Houston and Norias deltas, Greta-Carancahua barrier/strandplain system) that were respectively active along the upper, lower, and middle Texas Coast during Frio deposition. Within an area, salinities are usually depth dependent, and primary trends closely correspond to pore pressure gradients and thermal gradients. Where data are available (mainly in Brazoria County) the increases in TDS and calcium with depth coincide with the zone of albitization, smectite-illite transition, and calcite decrease in shales. Waters have fairly uniform salinities when produced from the same sandstone reservoir within a fault block or adjacent fault blocks with minor displacement. In contrast, stratigraphically equivalent sandstones separated by faults with large displacement usually yield waters with substantially different salinities owing to the markedly different thermal and pressure gradients across the faults that act as barriers to fluid movement.

  12. TEC variations over Europe during the solar eclipse of March 20, 2015 using GLONASS observations

    Science.gov (United States)

    Shagimuratov, Irk; Cherniak, Iurii; Krankowski, Andrzej; Zakharenkova, Irina; Yakimova, Galina; Tepenitzina, Nadezhda

    2016-07-01

    We report the features of the ionospheric TEC variations derived from the GLONASS measurements during the partial solar eclipse of March 20, 2015. Over Europe the maximal phase of the eclipse was observed around 10 UT. The eclipse took place during period when the ionosphere changed from night to day conditions. This eclipse occurred on the recovery phase of the strong geomagnetic storm of March 17, 2015. The effect of the eclipse was detected in diurnal variations of TEC over the individual GNSS stations as a trough-like variation with a gradual decrease and a succeeding increase of TEC at the time of the eclipse. The eclipse effect on the TEC distribution was observed more distinctly along individual satellite passes. Over the Kaliningrad GNSS station (54N, 20E) we registered the maximal TEC depression of about 4-6 TECU along several satellite passes. We should note that analysis of the ionospheric effects of the solar eclipse was complicated by the geomagnetic storm of March 17. The superposition of the storm and the eclipse make it difficult to separate the absolute TEC changes caused by the eclipse. At the same time the strong changes of the spatial structure of the TEC distribution were registered on the TEC maps. To analyze the spatial TEC distribution during the eclipse the TEC maps with high spatial-temporal resolution were produced. We used the GLONSS measurements derived from 150-180 stations of the dense European GNSS network. Dynamics of the ionospheric plasma density was analyzed using the mixture GLONASS-GPS TEC maps produced with 5 min sampling rate. The spatial structure of the ionosphere changed essentially during the eclipse comparing with the control days. The occurred TEC gradients were quite different comparing with previous and subsequent days. The complex pattern in the spatial-temporal TEC distribution highlights the important role of the dynamic processes in the ionosphere during the eclipse.

  13. 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.

  14. Observations of Seasonal Variations of Mesosphere and Lower Thermosphere Tides by the TIMED Doppler Interferometer

    Science.gov (United States)

    Killeen, T. L.; Wu, Q.; Clyne, J.; Gablehouse, R. D.; Gell, D. A.; Johnson, R. M.; Kafkalidis, J. F.; Niciejewski, R. J.; Ortland, D. A.; Skinner, W. R.; Solomon, S. C.

    2003-12-01

    Using neutral wind measurements by the TIMED Doppler Interferometer (TIDI), we examine seasonal variations in the migrating tide. TIDI samples four local times at latitudes between 60N and 60S on every orbit. The instrument measures winds from 70 to 105 km altitude during the day and 85 to 100 km during the night. Since the orbital precession rate of the TIMED satellite is 3 degree/day, it takes 60 days (one yaw period) for TIDI to sample the full range of solar times. We examine the possibility of extracting tidal wave features using data periods of less than 60 days. In spite of the limitation on local time coverage, TIDI can provide a global view of the tidal structure. The observational results will be compared with model runs from GSWM02 and the TIME-GCM. We also compare tidal amplitudes and phases obtained from TIDI with ground-based observations.

  15. 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

  16. 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...

  17. Morphology and time variation of the Jovian Far UV aurora: Hubble Space Telescope observations

    Science.gov (United States)

    Gerard, Jean-Claude; Dols, Vincent; Paresce, Francesco; Prange, Renee

    1993-01-01

    High spatial resolution images of the north polar region of Jupiter have been obtained with the Faint Object Camera (FOC) on board the Hubble Space Telescope (HST). The first set of two images collected 87 min apart in February 1992 shows a bright (approximately or equal to 180 kR) emission superimposed on the background in rotation with the planet. Both Ly alpha images show common regions of enhanced emission but differences are also observed, possibly due to temporal variations. The second group of images obtained on June 23 and 26, 1992 isolates a spectral region near 153 nm dominated by the H2 Lyman bands and continuum. Both pictures exhibit a narrow arc structure fitting the L = 30 magnetotail field line footprint in the morning sector and a broader diffuse aurora in the afternoon. They show no indication of an evening twilight enhancement. Although the central meridian longitudes were similar, significant differences are seen in the two exposures, especially in the region of diffuse emission, and interpreted as signatures of temporal variations. The total power radiated in the H2 bands is approximately or equal to 2 x 10(exp 12) W, in agreement with previous UV spectrometer observations. The high local H2 emission rates (approximately 450 kR) imply a particle precipitation carrying an energy flux of about 5 x 10(exp -2) W/sq m.

  18. TSUBASA (MDS-1) observations of energetic electrons and magnetic field variations in outer radiation belt

    Science.gov (United States)

    Nakamura, M.; Matsuoka, H.; Liu, H.; Koshiishi, H.; Koga, K.; Matsumoto, H.; Goka, T.

    2002-12-01

    We have investigated variations of energetic electrons (> 0.4 MeV) and magnetic field in the radiation belt obtained from the Standard DOse Monitor (SDOM) and the MAgnetoMeter (MAM) of the Space Environment Data Acquisition equipment (SEDA) onboard TSUBASA (the Mission Demonstration Test Satellite (MDS)-1) launched on February 4, 2002. Since TSUBASA is operated in the geostationary transfer orbit, it has provided rare opportunities of directly observing near-equatorial radiation belt plasma particles and magnetic field, having already included several large magnetic storms. The energetic electrons in the outer radiation belt are contributors to the total radiation dose deposited in lightly shielded spacecraft electronics for high altitude orbits and are known to have a drastic variability associated with geomagnetic storm and high speed solar wind streams. The abrupt energetic electron flux decreases in the outside of outer radiation belt show characteristic variations of in situ magnetic field. These observations have implications for the possible mechanisms of the depletion and the following recovery and/or buildup of energetic electrons in the outer radiation belt.

  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. Dynamic Responses of the Earth's Outer Core to Assimilation of Observed Geomagnetic Secular Variation

    Science.gov (United States)

    Kuang, Weijia; Tangborn, Andrew

    2014-01-01

    Assimilation of surface geomagnetic observations and geodynamo models has advanced very quickly in recent years. However, compared to advanced data assimilation systems in meteorology, geomagnetic data assimilation (GDAS) is still in an early stage. Among many challenges ranging from data to models is the disparity between the short observation records and the long time scales of the core dynamics. To better utilize available observational information, we have made an effort in this study to directly assimilate the Gauss coefficients of both the core field and its secular variation (SV) obtained via global geomagnetic field modeling, aiming at understanding the dynamical responses of the core fluid to these additional observational constraints. Our studies show that the SV assimilation helps significantly to shorten the dynamo model spin-up process. The flow beneath the core-mantle boundary (CMB) responds significantly to the observed field and its SV. The strongest responses occur in the relatively small scale flow (of the degrees L is approx. 30 in spherical harmonic expansions). This part of the flow includes the axisymmetric toroidal flow (of order m = 0) and non-axisymmetric poloidal flow with m (is) greater than 5. These responses can be used to better understand the core flow and, in particular, to improve accuracies of predicting geomagnetic variability in future.

  2. Airborne observations of regional variation in fluorescent aerosol across the United States

    Science.gov (United States)

    Perring, A. E.; Schwarz, J. P.; Baumgardner, D.; Hernandez, M. T.; Spracklen, D. V.; Heald, C. L.; Gao, R. S.; Kok, G.; McMeeking, G. R.; McQuaid, J. B.; Fahey, D. W.

    2015-02-01

    Airborne observations of fluorescent aerosol were made aboard an airship during CloudLab, a series of flights that took place in September and October of 2013 and covered a wideband of longitude across the continental U.S. between Florida and California and between 28 and 37 N latitudes. Sampling occurred from near the surface to 1000 m above the ground. A Wideband Integrated Bioaerosol Sensor (WIBS-4) measured average concentrations of supermicron fluorescent particles aloft (1 µm to 10 µm), revealing number concentrations ranging from 2.1 ± 0.8 to 8.7 ± 2.2 × 104 particles m-3 and representing up to 24% of total supermicron particle number. We observed distinct variations in size distributions and fluorescent characteristics in different regions, and attribute these to geographically diverse bioaerosol. Fluorescent aerosol detected in the east is largely consistent with mold spores observed in a laboratory setting, while a shift to larger sizes associated with different fluorescent patterns is observed in the west. Fluorescent bioaerosol loadings in the desert west were as high as those near the Gulf of Mexico, suggesting that bioaerosol is a substantial component of supermicron aerosol both in humid and arid environments. The observations are compared to model fungal and bacterial loading predictions, and good agreement in both particle size and concentrations is observed in the east. In the west, the model underestimated observed concentrations by a factor between 2 and 4 and the prescribed particle sizes are smaller than the observed fluorescent aerosol. A classification scheme for use with WIBS data is also presented.

  3. Physico-chemical Parameters and Their Variations in Relation to Fish Production in Zhob River Balochistan

    Directory of Open Access Journals (Sweden)

    Ghulam Dastagir

    2014-12-01

    Full Text Available The study of physico-chemical parameters of Zhob River was carried from January- December 2011 and correlated with fish production. The samples of fish were procured from, Zhob River Balochistan with the help of local fishermen. Total 557 (342 Schizothorax progestus, 105 Caratus auratus, 60 Tor tor and 50 Glypothorax sp. were procured from January to December. Noticeable difference in the values of temperature, pH, transparency and DO were not observed throughout the year and as per standards for aquatic biota. The length- weight relationship values indicated positive allometric and regression co-efficients (b are 2.67, 2.50, 2.17 and 2.65 termed as satisfactory growth in C. auratus, S. progestus, Tor tor and Glypothorax sp., respectively. The values of condition factor (Kn = 1.0, 1.01, 0.97 and 1.31 in case of C. auratus, S. progestus, Tor tor and Glypothorax sp.respectively from Zhob River, Balochistan. Condition factor values show fluctuations in all size groups in different fish species. It is concluded that the physico-chemical parameters of Zhob river Balochistan were found to be within the suitable ranges of fish culture.

  4. 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.

  5. 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.

  6. 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.

  7. 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...

  8. Investigation of Precipitation Variations over Wet and Dry Areas from Observation and Model

    Directory of Open Access Journals (Sweden)

    James H. Trammell

    2015-01-01

    Full Text Available Our observational study revealed that the precipitation increased over the wet area and decreased over the dry area during the past two decades. Here, we further investigate whether the current atmospheric models can quantitatively capture the characteristics of precipitation from the observation. The NASA Goddard Institute for Space Studies (GISS model is used to examine the historic simulation of the precipitation, in which the historic greenhouse gases and aerosols are included in the radiative forcing. The consistency between the historic GISS simulation and the Global Precipitation Climatology Project (GPCP precipitation suggests that the model can qualitatively capture the temporal trends of precipitation over the wet and dry areas. However, the precipitation trends are weaker in the model than in the observation. The observed trends of precipitation do not appear in the control simulation with the fixed concentrations of greenhouse gases and aerosols, which suggests that the global warming due to anthropogenic forcing can influence the temporal variations of precipitation over the wet and dry areas. Diagnostic studies of other variables from the model further suggest that enhanced rising air can increase the precipitation over the wet area.

  9. Variations in the chemical composition of cassava ( Manihot esculenta Crantz) leaves and roots as affected by genotypic and environmental variation.

    Science.gov (United States)

    Burns, Anna Elizabeth; Gleadow, Roslyn Margaret; Zacarias, Anabela M; Cuambe, Constantino Estevão; Miller, Rebecca Elizabeth; Cavagnaro, Timothy Richard

    2012-05-16

    The purpose of this study was to assess the quality of cassava cultivars, in terms of cyanogenic potential and composition of macro- and micronutrients, sampled from different locations in rural Mozambique. Total cyanide concentrations in fresh cassava tissues were measured using portable cyanide testing kits, and elemental nutrients were later analyzed from dried plant tissue. Variation in cyanogenic potential and nutrient composition occurred both among cultivars and across locations. The majority of cultivars contained >100 ppm total cyanide, fresh weight, and are therefore considered to be dangerously poisonous unless adequately processed before consumption. Leaf cyanogenic and nutrient content varied with plant water status, estimated using carbon isotope discrimination (δ(13)C). The colonization of roots of all cultivars by arbuscular mycorrhizal fungi was also quantified and found to be high, indicating that mycorrhizas could play a key role in plant nutrient acquisition in these low-input farming systems.

  10. Variation of the vertical distribution of Nabro volcano aerosol layers in the stratosphere observed by LIDAR

    Science.gov (United States)

    Noh, Young Min; Shin, Dong Ho; Müller, Detlef

    2017-04-01

    We present results of the vertical distribution variation of volcanic aerosol layers in the upper troposphere and lower stratosphere. The data were taken with our multiwavelength aerosol Raman lidar at Gwangju (35.10° N, 126.53° E), Korea. The volcanic ash particles and gases were released around 12 June 2011 during the eruption of the Nabro volcano (13.37° N, 41.7° E) in Eritrea, east Africa. Forward trajectory computations show that the volcanic aerosols were advected from North Africa to East Asia. The first measurement of the aerosol layer over Korea was on 19 June 2011. The aerosol layers appeared between 15 km and 17 km height asl (above sea level). The maximum value of the aerosol layer of the particle backscatter coefficient (1.5 ± 0.3 Mm-1 sr-1) and the linear particle depolarization ratio at 532 nm (2.2%) were observed at 16.4 km height asl. We continuously probed the upper troposphere and lower stratosphere for this volcanic aerosol layer during the following 6 months, until December 2011. The volcanic aerosol layer showed a single-peak of the particle backscatter coefficient and a comparably narrow vertical thickness at our observation site at the beginning of our observation period (i.e. comparably soon after the initial eruption period). After that initial period the vertical distribution of the plume changed. Multiple peaks and a comparably broad geometrical thickness developed with progressing observation time. The vertical thickness of the volcanic aerosol layer expanded up to 10 km by 3 August 2011. The linear particle depolarization ratios were larger in the lower part of the aerosol layer than the upper part of the aerosol layer. We observed a strong variation of the AOD (aerosol optical depth) in the first two months of our lidar observations. After these two months the AOD gradually decreased with time from September to December 20111 and the maximum particle backscatter coefficients consistently decreased. The corresponding e

  11. Modelling cycle to cycle variations in an SI engine with detailed chemical kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Etheridge, Jonathan; Mosbach, Sebastian; Kraft, Markus [Department of Chemical Engineering and Biotechnology, University of Cambridge (United Kingdom); Wu, Hao; Collings, Nick [Department of Engineering, University of Cambridge (United Kingdom)

    2011-01-15

    This paper presents experimental results and a new computational model that investigate cycle to cycle variations (CCV) in a spark ignition (SI) engine. An established stochastic reactor model (SRM) previously used to examine homogeneous charge compression ignition (HCCI) combustion has been extended by spark initiation, flame propagation and flame termination sub-models in order to simulate combustion in SI engines. The model contains a detailed chemical mechanism but relatively short computation times are achieved. The flame front is assumed to be spherical and centred at the spark location, and a pent roof and piston bowl geometry are accounted for. The model is validated by simulating the pressure profile and emissions from an iso-octane fuelled single cylinder research engine that showed low CCV. The effects of key parameters are investigated. Experimental results that show cycle to cycle fluctuations in a four-cylinder naturally aspirated gasoline fuelled SI engine are presented. The model is then coupled with GT-Power, a one-dimensional engine simulation tool, which is used to simulate the breathing events during a multi-cycle simulation. This allows an investigation of the cyclic fluctuations in peak pressure. The source and magnitude of nitric oxide (NO) emissions produced by different cycles are then investigated. It was found that faster burning cycles result in increased NO emissions compared with cycles that have a slower rate of combustion and that more is produced in the early stages of combustion compared with later in the cycle. The majority of NO was produced via the thermal mechanism just after combustion begins. (author)

  12. Clasp/SJ Observation of Time Variations of Lyman-Alpha Emissions in a Solar Active Region

    Science.gov (United States)

    Ishikawa, S.; Kubo, M.; Katsukawa, Y.; Kano, R.; Narukage, N.; Ishikawa, R.; Bando, T.; Winebarger, A.; Kobayashi, K.; Trujillo Bueno, J.; Auchere, F.

    2016-01-01

    The Chromospheric Lyman-alpha SpectroPolarimeter (CLASP) is a sounding rocket experiment launched on September 3, 2015 to investigate the solar chromosphere, and the slit-jaw (SJ) optical system took Lya images with the high time cadence of 0.6 s. By the CLASP/SJ observation, many time variations in the solar chromosphere with the time scale of time variations and relation to the coronal structure observed by SDO/AIA. We compared the Ly(alpha) time variations at footpoints of coronal magnetic fields observed by AIA 211 Å (approx.2 MK) and AIA 171 Å (0.6 MK), and non-loop regions. As the result, we found the time variations had more in the footpoint regions. On the other hand, the time variations had no dependency on the temperature of the loop.

  13. Variations of the aerosol concentration and chemical composition over the arid steppe zone of Southern Russia in summer

    Science.gov (United States)

    Artamonova, M. S.; Gubanova, D. P.; Iordanskii, M. A.; Lebedev, V. A.; Maksimenkov, L. O.; Minashkin, V. M.; Obvintsev, Y. I.; Chketiani, O. G.

    2016-12-01

    Variations in the surface aerosol over the arid steppe zone of Southern Russia have been measured. The parameters of atmospheric aerosol (mass concentration, both dispersed and elemental compositions) and meteorological parameters were measured in Tsimlaynsk raion (Rostov oblast). The chemical composition of aerosol particles in the atmospheric surface layer has been determined, and the coefficients of enrichment of elements with respect to clarkes in the Earth's crust have been calculated. It is shown that, in summer, arid aerosols are transported from both alkaline and sandy soils of Kalmykia to the air basin over the observation zone. Aerosol particles in the surface air layer over this region have been found to contain the products of combustion of oil, coal, and ethylized fuel. These combustion products make a small contribution to the total mass concentration of atmospheric aerosol; however, they are most hazardous to the health of people because of their sizes and heavy-metal contents. A high concentration of submicron sulfur-containing aerosol particles of chemocondensation nature has been recorded. Sources of aerosol of both natural and anthropogenic origins in southern Russia are discussed.

  14. Temporal variations in physical and chemical features of cryoconite holes on Canada Glacier, McMurdo Dry Valleys, Antarctica

    Science.gov (United States)

    Fountain, Andrew G.; Nylen, Thomas H.; Tranter, Martyn; Bagshaw, Elizabeth

    2008-03-01

    Cryoconite holes in the McMurdo Dry Valleys are ice-lidded, thus isolating the pools of water from the atmosphere and from potential surface melt. Hourly measurements of ice and water temperature and water electrical conductivity (EC) were recorded to broadly characterize the physical and chemical changes on daily to seasonal timescales. Overall, subsurface ice/water temperatures were typically several degrees warmer than air temperatures, underscoring the importance of subsurface solar heating. At no time was surface melt observed and the holes melted from within. Detailed differences in the timing and magnitude of both temperature and EC variations during melt-out and freezeup existed between holes despite short separation distances (<1 m). We attribute these differences to small-scale changes in the optical characteristics of the ice and perhaps different efficiencies in hydrologic connections between holes. The holes melt-deepened quickly in the first half of the summer before slowing to a rate equal to the rate of surface ablation that kept hole depth constant for the remainder of the season. The relatively constant EC of the hole waters during midsummer indicates that these holes were connected to a subsurface water system that flushed the holes with fresher meltwater. The early and late season ECs are dominated by freeze-thaw effects that concentrate/dilute the solutes. We speculate that high solute concentrations imply high nutrient concentrations in early summer that may help alleviate potential stresses caused by the production of new biomass after the winter freeze.

  15. divand-1.0: n-dimensional variational data analysis for ocean observations

    Directory of Open Access Journals (Sweden)

    A. Barth

    2013-07-01

    Full Text Available A tool for multidimensional variational analysis (divand is presented. It allows the interpolation and analysis of observations on curvilinear orthogonal grids in an arbitrary high dimensional space by minimizing a cost function. This cost function penalizes the deviation from the observations, the deviation from a first guess and abruptly varying fields based on a given correlation length (potentially varying in space and time. Additional constraints can be added to this cost function such as an advection constraint which forces the analysed field to align with the ocean current. The method decouples naturally disconnected areas based on topography and topology. This is useful in oceanography where disconnected water masses often have different physical properties. Individual elements of the a priori and a posteriori error covariance matrix can also be computed, in particular expected error variances of the analysis. A multidimensional approach (as opposed to stacking 2-dimensional analysis has the benefit of providing a smooth analysis in all dimensions, although the computational cost it increased. Primal (problem solved in the grid space and dual formulations (problem solved in the observational space are implemented using either direct solvers (based on Cholesky factorization or iterative solvers (conjugate gradient method. In most applications the primal formulation with the direct solver is the fastest, especially if an a posteriori error estimate is needed. However, for correlated observation errors the dual formulation with an iterative solver is more efficient. The method is tested by using pseudo observations from a global model. The distribution of the observations is based on the position of the ARGO floats. The benefit of the 3-dimensional analysis (longitude, latitude and time compared to 2-dimensional analysis (longitude and latitude and the role of the advection constraint are highlighted. The tool divand is free software, and

  16. Marked variation in predicted and observed variability of tandem repeat loci across the human genome

    Directory of Open Access Journals (Sweden)

    Shields Denis C

    2008-04-01

    Full Text Available Abstract Background Tandem repeat (TR variants in the human genome play key roles in a number of diseases. However, current models predicting variability are based on limited training sets. We conducted a systematic analysis of TRs of unit lengths 2–12 nucleotides in Whole Genome Shotgun (WGS sequences to define the extent of variation of 209,214 unique repeat loci throughout the genome. Results We applied a multivariate statistical model to predict TR variability. Predicted heterozygosity correlated with heterozygosity in the CEPH polymorphism database (correlation ρ = 0.29, p Conclusion Variability among 2–12-mer TRs in the genome can be modeled by a few parameters, which do not markedly differ according to unit length, consistent with a common mechanism for the generation of variability among such TRs. Analysis of the distributions of observed and predicted variants across the genome showed a general concordance, indicating that the repeat variation dataset does not exhibit strong regional ascertainment biases. This revealed a deficit of variant repeats in chromosomes 19 and Y – likely to reflect a reduction in 2-mer repeats in the former and a reduced level of recombination in the latter – and excesses in chromosomes 6, 13, 20 and 21.

  17. Temporal variation and provenance of thorium deposition observed at Tsukuba, Japan.

    Science.gov (United States)

    Hirose, Katsumi; Kikawada, Yoshikazu; Igarashi, Yasuhito

    2012-06-01

    Temporal variations of monthly thorium (Th) deposition observed at Tsukuba, Japan during the period 1990-2007, comparing with plutonium deposition, was studied. The monthly (232)Th deposition as did (239,240)Pu, varied according to season and inter-annually. In particular, (232)Th deposition increased significantly in spring coinciding with Asian dust (Kosa) events. The (230)Th/(232)Th activity ratios vary according to sources and can therefore be used to differentiate between locally derived and remotely derived (232)Th. The (230)Th/(232)Th activity ratios in deposition samples showed large variability with high ratios occurring in early spring. These high (230)Th/(232)Th ratios in deposition can be attributed to local dust storms, especially in early spring, that cause resuspension of soils from cultivated fields which are characterized by high (230)Th/(232)Th activity ratios. The results reveal that both locally and remotely derived (232)Th deposition showed seasonal variations with maxima in spring, although the remotely derived fraction is dominant rather than the locally derived one. The (232)Th deposition maxima later in spring is attributable to the remotely derived fraction, corresponding to the Kosa events. Annual (232)Th deposition exhibited an increasing trend, suggesting the presence of sources other than soil dust such as fly ash from increasing coal burning.

  18. 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...

  19. Chaotic behaviour of the short-term variations in ozone column observed in Arctic

    Science.gov (United States)

    Petkov, Boyan H.; Vitale, Vito; Mazzola, Mauro; Lanconelli, Christian; Lupi, Angelo

    2015-09-01

    The diurnal variations observed in the ozone column at Ny-Ålesund, Svalbard during different periods of 2009, 2010 and 2011 have been examined to test the hypothesis that they could be a result of a chaotic process. It was found that each of the attractors, reconstructed by applying the time delay technique and corresponding to any of the three time series can be embedded by 6-dimensional space. Recurrence plots, depicted to characterise the attractor features revealed structures typical for a chaotic system. In addition, the two positive Lyapunov exponents found for the three attractors, the fractal Hausdorff dimension presented by the Kaplan-Yorke estimator and the feasibility to predict the short-term ozone column variations within 10-20 h, knowing the past behaviour make the assumption about their chaotic character more realistic. The similarities of the estimated parameters in all three cases allow us to hypothesise that the three time series under study likely present one-dimensional projections of the same chaotic system taken at different time intervals.

  20. Observations of hysteresis in solar cycle variations among seven solar activity indicators

    Science.gov (United States)

    Bachmann, Kurt T.; White, Oran R.

    1994-01-01

    We show that smoothed time series of 7 indices of solar activity exhibit significant solar cycle dependent differences in their relative variations during the past 20 years. In some cases these observed hysteresis patterns start to repeat over more than one solar cycle, giving evidence that this is a normal feature of solar variability. Among the indices we study, we find that the hysteresis effects are approximately simple phase shifts, and we quantify these phase shifts in terms of lag times behind the leading index, the International Sunspot Number. Our measured lag times range from less than one month to greater than four months and can be much larger than lag times estimated from short-term variations of these same activity indices during the emergence and decay of major active regions. We argue that hysteresis represents a real delay in the onset and decline of solar activity and is an important clue in the search for physical processes responsible for changing solar emission at various wavelengths.

  1. Variation in antibiotic treatment for diabetic patients with serious foot infections: A retrospective observational study

    Directory of Open Access Journals (Sweden)

    Christiansen Cindy L

    2010-07-01

    Full Text Available Abstract Background Diabetic foot infections are common, serious, and diverse. There is uncertainty about optimal antibiotic treatment, and probably substantial variation in practice. Our aim was to document whether this is the case: A finding that would raise questions about the comparative cost-effectiveness of different regimens and also open the possibility of examining costs and outcomes to determine which should be preferred. Methods We used the Veterans Health Administration (VA Diabetes Epidemiology Cohorts (DEpiC database to conduct a retrospective observational study of hospitalized patients with diabetic foot infections. DEpiC contains computerized VA and Medicare patient-level data for VA patients with diabetes since 1998, including demographics, ICD-9-CM diagnostic codes, antibiotics prescribed, and VA facility. We identified all patients with ICD-9-CM codes for cellulitis/abscess of the foot and then sub-grouped them according to whether they had cellulitis/abscess plus codes for gangrene, osteomyelitis, skin ulcer, or none of these. For each facility, we determined: 1 The proportion of patients treated with an antibiotic and the initial route of administration; 2 The first antibiotic regimen prescribed for each patient, defined as treatment with the same antibiotic, or combination of antibiotics, for at least 5 continuous days; and 3 The antibacterial spectrum of the first regimen. Results We identified 3,792 patients with cellulitis/abscess of the foot either alone (16.4%, or with ulcer (32.6%, osteomyelitis (19.0% or gangrene (32.0%. Antibiotics were prescribed for 98.9%. At least 5 continuous days of treatment with an unchanged regimen of one or more antibiotics was prescribed for 59.3%. The means and (ranges across facilities of the three most common regimens were: 16.4%, (22.8%; 15.7%, (36.1%; and 10.8%, (50.5%. The range of variation across facilities proved substantially greater than that across the different categories of

  2. The contribution of simple random sampling to observed variations in faecal egg counts.

    Science.gov (United States)

    Torgerson, Paul R; Paul, Michaela; Lewis, Fraser I

    2012-09-10

    It has been over 100 years since the classical paper published by Gosset in 1907, under the pseudonym "Student", demonstrated that yeast cells suspended in a fluid and measured by a haemocytometer conformed to a Poisson process. Similarly parasite eggs in a faecal suspension also conform to a Poisson process. Despite this there are common misconceptions how to analyse or interpret observations from the McMaster or similar quantitative parasitic diagnostic techniques, widely used for evaluating parasite eggs in faeces. The McMaster technique can easily be shown from a theoretical perspective to give variable results that inevitably arise from the random distribution of parasite eggs in a well mixed faecal sample. The Poisson processes that lead to this variability are described and illustrative examples of the potentially large confidence intervals that can arise from observed faecal eggs counts that are calculated from the observations on a McMaster slide. Attempts to modify the McMaster technique, or indeed other quantitative techniques, to ensure uniform egg counts are doomed to failure and belie ignorance of Poisson processes. A simple method to immediately identify excess variation/poor sampling from replicate counts is provided.

  3. Observer variations in short period spectral analysis of heart rate variability.

    Science.gov (United States)

    van Schelven, L J; Oey, P L; Klein, I H; Barnas, M G; Blankestijn, P J; Wieneke, G H

    2000-03-15

    25% of the corresponding mean LF/HF ratio. The smallest interobserver variations were found for the 'fixed frequency' method. The data showed that it is advantageous to select the 3-min ECG periods but not to select the frequency regions. Selection of the latter led to an increase in interobserver variation. The results of this study give a realistic impression of the intrasubject and interobserver variation to be expected when measuring the LF/HF ratio. This variation is considerable.

  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 ¡_10¢X 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. Assessment of radiative feedback in climate models using satellite observations of annual flux variation.

    Science.gov (United States)

    Tsushima, Yoko; Manabe, Syukuro

    2013-05-07

    In the climate system, two types of radiative feedback are in operation. The feedback of the first kind involves the radiative damping of the vertically uniform temperature perturbation of the troposphere and Earth's surface that approximately follows the Stefan-Boltzmann law of blackbody radiation. The second kind involves the change in the vertical lapse rate of temperature, water vapor, and clouds in the troposphere and albedo of the Earth's surface. Using satellite observations of the annual variation of the outgoing flux of longwave radiation and that of reflected solar radiation at the top of the atmosphere, this study estimates the so-called "gain factor," which characterizes the strength of radiative feedback of the second kind that operates on the annually varying, global-scale perturbation of temperature at the Earth's surface. The gain factor is computed not only for all sky but also for clear sky. The gain factor of so-called "cloud radiative forcing" is then computed as the difference between the two. The gain factors thus obtained are compared with those obtained from 35 models that were used for the fourth and fifth Intergovernmental Panel on Climate Change assessment. Here, we show that the gain factors obtained from satellite observations of cloud radiative forcing are effective for identifying systematic biases of the feedback processes that control the sensitivity of simulated climate, providing useful information for validating and improving a climate model.

  6. Variation Theory: A Theory of Learning and a Useful Theoretical Framework for Chemical Education Research

    Science.gov (United States)

    Bussey, Thomas J.; Orgill, MaryKay; Crippen, Kent J.

    2013-01-01

    Instructors are constantly baffled by the fact that two students who are sitting in the same class, who have access to the same materials, can come to understand a particular chemistry concept differently. Variation theory offers a theoretical framework from which to explore possible variations in experience and the resulting differences in…

  7. Can Galactic chemical evolution explain the oxygen isotopic variations in the Solar System?

    CERN Document Server

    Lugaro, Maria; Ireland, Trevor R; Maddison, Sarah T

    2012-01-01

    A number of objects in primitive meteorites have oxygen isotopic compositions that place them on a distinct, mass-independent fractionation line with a slope of one on a three-isotope plot. The most popular model for describing how this fractionation arose assumes that CO self-shielding produced 16O-rich CO and 16O-poor H2O, where the H2O subsequently combined with interstellar dust to form relatively 16O-poor solids within the Solar Nebula. Another model for creating the different reservoirs of 16O-rich gas and 16O-poor solids suggests that these reservoirs were produced by Galactic chemical evolution (GCE) if the Solar System dust component was somewhat younger than the gas component and both components were lying on the line of slope one in the O three-isotope plot. We argue that GCE is not the cause of mass-independent fractionation of the oxygen isotopes in the Solar System. The GCE scenario is in contradiction with observations of the 18O/17O ratios in nearby molecular clouds and young stellar objects. ...

  8. 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

  9. 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; Jiang, Hao; Tang, Feng; Chin, Kit L.

    2015-01-01

    Abstract 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

  10. Observations of Altitude Dependence and Temporal Variation of ClO in the Venus Mesosphere

    Science.gov (United States)

    Sandor, Brad J.; Clancy, R. Todd

    2015-11-01

    Analysis of the first observations of ClO in the Venus mesosphere indicate ClO is present above 85 +/-3 km altitude and not below. The retrieved nightside mean abundances show a factor of 2 decrease between observation dates Oct. 23 and Nov. 11, 2015, with change between the two dates evident at more than two sigma confidence. Abundances and altitude distributions are retrieved from submm spectroscopic observations of the 352.88 GHz line of 35ClO (made with the James Clerk Maxwell Telescope - JCMT - located an Mauna Kea, Hawaii).Detection of ClO in the Venus atmosphere confirms a theory put forward by Yung and DeMore (1982) that the Venus atmosphere is stabilized as CO2 due to chlorine catalytic recombination of CO and O. (Without some form of catalysis, the Venus atmosphere would have 10s of percent CO and O2, but it is in fact 97% CO2 and 3% N2, with only trace amounts of CO and O2.) Detailed retrieval of ClO abundances and altitude distributions (the focus of this talk) provides greater insight to the catalytic process, and to other aspects of Venus atmospheric chlorine chemistry. We compare findings of our quantitave retrieval with predictions of photochemical models, and discuss the implications for chlorine photochemisty of the Venus atmosphere. We also discuss retrieved ClO temporal variation with that of upper mesospheric HCl (Sandor and Clancy, 2012).[We acknowledge funding of this project by NASA grants NNX10AB33G, NNX12AI32G, and NNX14AK05G, as well as NSF grant AST-1312985.

  11. 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

  12. 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.

  13. Soft Sensor for Inputs and Parameters Using Nonlinear Singular State Observer in Chemical Processes

    Institute of Scientific and Technical Information of China (English)

    许锋; 汪晔晔; 罗雄麟

    2013-01-01

    Chemical processes are usually nonlinear singular systems. In this study, a soft sensor using nonlinear singular state observer is established for unknown inputs and uncertain model parameters in chemical processes, which are augmented as state variables. Based on the observability of the singular system, this paper presents a simplified observability criterion under certain conditions for unknown inputs and uncertain model parameters. When the observability is satisfied, the unknown inputs and the uncertain model parameters are estimated online by the soft sensor using augmented nonlinear singular state observer. The riser reactor of fluid catalytic cracking unit is used as an example for analysis and simulation. With the catalyst circulation rate as the only unknown input without model error, one temperature sensor at the riser reactor outlet will ensure the correct estimation for the catalyst cir-culation rate. However, when uncertain model parameters also exist, additional temperature sensors must be used to ensure correct estimation for unknown inputs and uncertain model parameters of chemical processes.

  14. 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.

  15. 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

  16. CAN GALACTIC CHEMICAL EVOLUTION EXPLAIN THE OXYGEN ISOTOPIC VARIATIONS IN THE SOLAR SYSTEM?

    Energy Technology Data Exchange (ETDEWEB)

    Lugaro, Maria [Monash Centre for Astrophysics (MoCA), Building 28, Monash University, Clayton, VIC 3800 (Australia); Liffman, Kurt [CSIRO/MSE, P.O. Box 56, Highett, VIC 3190 (Australia); Ireland, Trevor R. [Planetary Science Institute and Research School of Earth Sciences, Australian National University, Canberra, ACT 0200 (Australia); Maddison, Sarah T., E-mail: maria.lugaro@monash.edu [Centre for Astrophysics and Supercomputing, Swinburne University, H39, P.O. Box 218, Hawthorn, VIC 3122 (Australia)

    2012-11-01

    A number of objects in primitive meteorites have oxygen isotopic compositions that place them on a distinct, mass-independent fractionation line with a slope of one on a three-isotope plot. The most popular model for describing how this fractionation arose assumes that CO self-shielding produced {sup 16}O-rich CO and {sup 16}O-poor H{sub 2}O, where the H{sub 2}O subsequently combined with interstellar dust to form relatively {sup 16}O-poor solids within the solar nebula. Another model for creating the different reservoirs of {sup 16}O-rich gas and {sup 16}O-poor solids suggests that these reservoirs were produced by Galactic chemical evolution (GCE) if the solar system dust component was somewhat younger than the gas component and both components were lying on the line of slope one in the O three-isotope plot. We argue that GCE is not the cause of mass-independent fractionation of the oxygen isotopes in the solar system. The GCE scenario is in contradiction with observations of the {sup 18}O/{sup 17}O ratios in nearby molecular clouds and young stellar objects. It is very unlikely for GCE to produce a line of slope one when considering the effect of incomplete mixing of stellar ejecta in the interstellar medium. Furthermore, the assumption that the solar system dust was younger than the gas requires unusual timescales or the existence of an important stardust component that is not theoretically expected to occur nor has been identified to date.

  17. Observations of the stratospheric conductivity and its variation at three latitudes

    Science.gov (United States)

    Byrne, G. J.; Benbrook, J. R.; Bering, E. A.; Oro, D.; Seubert, C. O.

    1988-04-01

    Measurements from nine high-altitude balloon flights at altitudes ranging from 10 to 30 km have been obtained in order to study atmospheric conductivity variations on local and global scales. The conductivity profiles are not correlated with solar or cosmic ray activity, but they exhibit variations which appear to be dominated by local effects. Evidence is provided of stratospheric aerosol layers with number densities of the order of 1000/cu cm. It is suggested that global conductivity models employing latitudinal variations based on cosmic ray ionization alone may be improved by including the effects of latitudinal variations of temperature and aerosols.

  18. 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.

  19. Spatial and Temporal Variations of Surface Characteristics on the Greenland Ice Sheet as Derived from Passive Microwave Observations

    Science.gov (United States)

    Anderson, Mark; Rowe, Clinton; Kuivinen, Karl; Mote, Thomas

    1996-01-01

    The primary goals of this research were to identify and begin to comprehend the spatial and temporal variations in surface characteristics of the Greenland ice sheet using passive microwave observations, physically-based models of the snowpack and field observations of snowpack and firn properties.

  20. 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...

  1. Chemical variations in Yellowknife Bay formation sedimentary rocks analyzed by ChemCam on board the Curiosity rover on Mars

    Science.gov (United States)

    Mangold, Nicolas; Forni, Olivier; Dromart, G.; Stack, K.M.; Wiens, Roger C.; Gasnault, Olivier; Sumner, Dawn Y.; Nachon, Marion; Meslin, Pierre-Yves; Anderson, Ryan B.; Barraclough, Bruce; Bell, J.F.; Berger, G.; Blaney, D.L.; Bridges, J.C.; Calef, F.; Clark, Brian R.; Clegg, Samuel M.; Cousin, Agnes; Edgar, L.; Edgett, Kenneth S.; Ehlmann, B.L.; Fabre, Cecile; Fisk, M.; Grotzinger, John P.; Gupta, S.C.; Herkenhoff, Kenneth E.; Hurowitz, J.A.; Johnson, J. R.; Kah, Linda C.; Lanza, Nina L.; Lasue, Jeremie; Le Mouélic, S.; Lewin, Eric; Malin, Michael; McLennan, Scott M.; Maurice, S.; Melikechi, Noureddine; Mezzacappa, Alissa; Milliken, Ralph E.; Newsome, H.L.; Ollila, A.; Rowland, Scott K.; Sautter, Violaine; Schmidt, M.E.; Schroder, S.; D'Uston, C.; Vaniman, Dave; Williams, R.A.

    2015-01-01

    The Yellowknife Bay formation represents a ~5 m thick stratigraphic section of lithified fluvial and lacustrine sediments analyzed by the Curiosity rover in Gale crater, Mars. Previous works have mainly focused on the mudstones that were drilled by the rover at two locations. The present study focuses on the sedimentary rocks stratigraphically above the mudstones by studying their chemical variations in parallel with rock textures. Results show that differences in composition correlate with textures and both manifest subtle but significant variations through the stratigraphic column. Though the chemistry of the sediments does not vary much in the lower part of the stratigraphy, the variations in alkali elements indicate variations in the source material and/or physical sorting, as shown by the identification of alkali feldspars. The sandstones contain similar relative proportions of hydrogen to the mudstones below, suggesting the presence of hydrous minerals that may have contributed to their cementation. Slight variations in magnesium correlate with changes in textures suggesting that diagenesis through cementation and dissolution modified the initial rock composition and texture simultaneously. The upper part of the stratigraphy (~1 m thick) displays rocks with different compositions suggesting a strong change in the depositional system. The presence of float rocks with similar compositions found along the rover traverse suggests that some of these outcrops extend further away in the nearby hummocky plains.

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

    Institute of Scientific and Technical Information of China (English)

    Gordon E.Sarty; László L.Kiss; Kinwah Wu; Bogumil Pilecki; Daniel E.Reichart; Kevin M.Ivarsen; Joshua B.Haislip; Melissa C.Nysewander; Aaron P.LaCluyze; Helen M.Johnston; Robert R.Shobbrook

    2011-01-01

    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 J 1037.5-5647,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 periodograms suggested the existence of long period variation in the V-band light curvesof 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.

  3. Trace metal concentrations in acidic, headwater streams in Sweden explained by chemical, climatic, and land use variations

    Directory of Open Access Journals (Sweden)

    B. J. Huser

    2012-02-01

    Full Text Available Long term data series (1996–2009 for eleven acidic, headwater streams (<10 km2 in Sweden were analyzed to determine factors controlling concentrations of trace metals. In-stream chemical data as well climatic, flow, and deposition chemistry data were used to develop models predicting concentrations of chromium (Cr, lead (Pb, and zinc (Zn. Data were initially analyzed using partial least squares to determine a set of variables that could predict metal concentrations across all sites. Organic matter (as absorbance and iron related positively to Pb and Cr while pH related negatively to Pb and Zn. Other variables such as conductivity, manganese, and temperature were important as well. Multiple linear regression was then used to determine minimally adequate prediction models which explained an average of 35% (Cr, 52% (Zn, and 72% (Pb of metal variation across all sites. While models explained at least 50% of variation in the majority of sites for Pb (10 and Zn (8, only three sites met this criterion for Cr. Investigation of variation between site models for each metal revealed geographical (altitude, chemical (sulfate, and land use (silvaculture influences on predictive power of the models. Residual analysis revealed seasonal differences in the ability of the models to predict metal concentrations as well. Expected future changes in model variables were applied and results showed the potential for long term increases (Pb or decreases (Zn for trace metal concentrations at these sites.

  4. Lead, zinc, and chromium concentrations in acidic headwater streams in Sweden explained by chemical, climatic, and land-use variations

    Directory of Open Access Journals (Sweden)

    B. J. Huser

    2012-11-01

    Full Text Available Long-term data series (1996–2009 for eleven acidic headwater streams (< 10 km2 in Sweden were analyzed to determine factors controlling concentrations of trace metals. In-stream chemical data as well climatic, flow, and deposition chemistry data were used to develop models predicting concentrations of chromium (Cr, lead (Pb, and zinc (Zn. Data were initially analyzed using partial least squares to determine a set of variables that could predict metal concentrations across all sites. Organic matter (as absorbance and iron related positively to Pb and Cr, while pH related negatively to Pb and Zn. Other variables such as conductivity, manganese, and temperature were important as well. Multiple linear regression was then used to determine minimally adequate prediction models which explained an average of 35% (Cr, 52% (Zn, and 72% (Pb of metal variation across all sites. While models explained at least 50% of variation in the majority of sites for Pb (10 and Zn (8, only three sites met this criterion for Cr. Investigation of variation between site models for each metal revealed geographical (altitude, chemical (sulfate, and land-use (silvaculture influences on predictive power of the models. Residual analysis revealed seasonal differences in the ability of the models to predict metal concentrations as well. Expected future changes in model variables were applied and results showed the potential for long-term increases (Pb or decreases (Zn for trace metal concentrations at these sites.

  5. CCN frequency distributions and aerosol chemical composition from long-term observations at European ACTRIS supersites

    Science.gov (United States)

    Decesari, Stefano; Rinaldi, Matteo; Schmale, Julia Yvonne; Gysel, Martin; Fröhlich, Roman; Poulain, Laurent; Henning, Silvia; Stratmann, Frank; Facchini, Maria Cristina

    2016-04-01

    Cloud droplet number concentration is regulated by the availability of aerosol acting as cloud condensation nuclei (CCN). Predicting the air concentrations of CCN involves knowledge of all physical and chemical processes that contribute to shape the particle size distribution and determine aerosol hygroscopicity. The relevance of specific atmospheric processes (e.g., nucleation, coagulation, condensation of secondary organic and inorganic aerosol, etc.) is time- and site-dependent, therefore the availability of long-term, time-resolved aerosol observations at locations representative of diverse environments is strategic for the validation of state-of-the-art chemical transport models suited to predict CCN concentrations. We focused on long-term (year-long) datasets of CCN and of aerosol composition data including black carbon, and inorganic as well as organic compounds from the Aerosol Chemical Speciation Monitor (ACSM) at selected ACTRIS supersites (http://www.actris.eu/). We discuss here the joint frequency distribution of CCN levels and of aerosol chemical components concentrations for two stations: an alpine site (Jungfraujoch, CH) and a central European rural site (Melpitz, DE). The CCN frequency distributions at Jungfraujoch are broad and generally correlated with the distributions of the concentrations of aerosol chemical components (e.g., high CCN concentrations are most frequently found for high organic matter or black carbon concentrations, and vice versa), which can be explained as an effect of the strong seasonality in the aerosol characteristics at the mountain site. The CCN frequency distributions in Melpitz show a much weaker overlap with the distributions of BC concentrations or other chemical compounds. However, especially at high CCN concentration levels, a statistical correlation with organic matter (OM) concentration can be observed. For instance, the number of CCN (with particle diameter between 20 and 250 nm) at a supersaturation of 0.7% is

  6. 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.

  7. Systematic Variations of Macrospicule Properties Observed by SDO/AIA over Half a Decade

    Science.gov (United States)

    Kiss, T. S.; Gyenge, N.; Erdélyi, R.

    2017-01-01

    Macrospicules (MSs) are localized small-scale jet-like phenomena in the solar atmosphere, which have the potential to transport a considerable amount of momentum and energy from the lower solar atmospheric regions to the transition region and the low corona. A detailed statistical analysis of their temporal behavior and spatial properties is carried out in this work. Using state-of-the-art spatial and temporal resolution observations, yielded by the Atmospheric Imaging Assembly of Solar Dynamics Observatory, we constructed a database covering a 5.5 year long period, containing 301 macrospicules that occurred between 2010 June and 2015 December, detected at 30.4 nm wavelength. Here, we report the long-term variation of the height, length, average speed, and width of MS in coronal holes and Quiet Sun areas both in the northern and southern hemisphere of the Sun. This new database helps to refine our knowledge about the physical properties of MSs. Cross-correlation of these properties shows a relatively strong correlation, but not always a dominant one. However, a more detailed analysis indicates a wave-like signature in the behavior of MS properties in time. The periods of these long-term oscillatory behaviors are just under two years. Also, in terms of solar north/south hemispheres, a strong asymmetry was found in the spatial distribution of MS properties, which may be accounted for by the solar dynamo. This latter feature may then indicate a strong and rather intrinsic link between global internal and local atmospheric phenomena in the Sun.

  8. Inference of Surface Chemical and Physical Properties Using Mid-Infrared (MIR) Spectral Observations

    Science.gov (United States)

    Roush, Ted L.

    2016-01-01

    Reflected or emitted energy from solid surfaces in the solar system can provide insight into thermo-physical and chemical properties of the surface materials. Measurements have been obtained from instruments located on Earth-based telescopes and carried on several space missions. The characteristic spectral features commonly observed in Mid-Infrared (MIR) spectra of minerals will be reviewed, along with methods used for compositional interpretations of MIR emission spectra. The influence of surface grain size, and space weathering processes on MIR emissivity spectra will also be discussed. Methods used for estimating surface temperature, emissivity, and thermal inertias from MIR spectral observations will be reviewed.

  9. 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

  10. 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

  11. Variation in the expression of chemical defenses in Alliaria petiolata (Brassicaceae) in the field and common garden.

    Science.gov (United States)

    Cipollini, Don

    2002-09-01

    I examined glucosinolates, trypsin inhibitors (TI), and peroxidase (POD) activity in garlic mustard (Alliaria petiolata) plants growing naturally in Wright State University's Forest Preserve and in a common garden experiment in plants from the same populations conducted in the greenhouse. In the field, first-year plants expressed each defense, but defense levels varied significantly in plants from different sites in the forest. Patterns in site variation were consistent for glucosinolate and POD, but not for TI. The TI and POD levels were increased by mechanical wounding, but glucosinolate levels were unaffected. In the greenhouse, plants expressed each defense at higher levels than in the field, but defense levels did not vary among plants collected from each site in the field. The POD activity was increased by wounding, but glucosinolate and TI levels where unaffected. Plants from each site varied in height and leaf length when measured shortly after transplantation, but site differences substantially diminished after 4 wk. Site-based variation in defense expression in the field, which disappeared in the greenhouse, was presumably related to differences in environmental quality among the sites. Sites were shown to vary in soil moisture content, soil pH, nutrient levels, and presumably light quantity or quality. Despite an apparent lack of genetic variation in defense across sites in the field, the constitutive expression of these three chemical defenses, increases due to wounding, and phenotypic variation across sites could reduce herbivore success on garlic mustard individuals and slow the rate of herbivore adaptation to garlic mustard populations.

  12. Chemically engineering ligand selectivity at the free fatty acid receptor 2 based on pharmacological variation between species orthologs

    Science.gov (United States)

    Hudson, Brian D.; Christiansen, Elisabeth; Tikhonova, Irina G.; Grundmann, Manuel; Kostenis, Evi; Adams, David R.; Ulven, Trond; Milligan, Graeme

    2012-01-01

    When it is difficult to develop selective ligands within a family of related G-protein-coupled receptors (GPCRs), chemically engineered receptors activated solely by synthetic ligands (RASSLs) are useful alternatives for probing receptor function. In the present work, we explored whether a RASSL of the free fatty acid receptor 2 (FFA2) could be developed on the basis of pharmacological variation between species orthologs. For this, bovine FFA2 was characterized, revealing distinct ligand selectivity compared with human FFA2. Homology modeling and mutational analysis demonstrated a single mutation in human FFA2 of C4.57G resulted in a human FFA2 receptor with ligand selectivity similar to the bovine receptor. This was exploited to generate human FFA2-RASSL by the addition of a second mutation at a known orthosteric ligand interaction site, H6.55Q. The resulting FFA2-RASSL displayed a >100-fold loss of activity to endogenous ligands, while responding to the distinct ligand sorbic acid with pEC50 values for inhibition of cAMP, 5.83 ± 0.11; Ca2+ mobilization, 4.63 ± 0.05; ERK phosphorylation, 5.61 ± 0.06; and dynamic mass redistribution, 5.35 ± 0.06. This FFA2-RASSL will be useful in future studies on this receptor and demonstrates that exploitation of pharmacological variation between species orthologs is a powerful method to generate novel chemically engineered GPCRs.—Hudson, B. D., Christiansen, E., Tikhonova, I. G., Grundmann, M., Kostenis, E., Adams, D. R., Ulven, T., Milligan, G. Chemically engineering ligand selectivity at the free fatty acid receptor 2 based on pharmacological variation between species orthologs. PMID:22919070

  13. Center-to-Limb Variation of Solar Granulation from Partial Eclipse Observations

    Science.gov (United States)

    Sánchez Cuberes, M.; Bonet, J. A.; Vázquez, M.; Wittmann, A. D.

    2000-08-01

    granular contours, has also been performed. A general increase in both granular and intergranular areas is found as we move toward the solar limb. The mean granular cell area varies from 1.36 Mm2 at μ=1 up to 2.06 Mm2 at μ=0.6, and in parallel, the granular filling factor (the percentage of area of the image covered by granules) decreases from 44.2% to 42.8%. In the small area range, the granular brightness increases linearly with the granular cell size and is preserved constant, on average, for granular cells larger than ~2.0". No slope variation is found for the intergranular intensities versus granular cell areas. Observations close to the solar limb detect granular structures as small as 0.53" or even smaller up to a distance of at least ~0.5" from the limb, showing that the ΔT associated with the granulation persist at least until z~200 km. However, this penetration could be different for small and large granules because we find several hints indicating the progressive disappearance of small structures toward the limb.

  14. Optical-chemical relationships for carbonaceous aerosols observed at Jeju Island, Korea with a 3-laser photoacoustic spectrometer

    Directory of Open Access Journals (Sweden)

    B. A. Flowers

    2010-04-01

    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. Transport of mixed sulfate, carbonaceous, and nitrate aerosols from various Asian pollution plumes to Jeju accounted for 76% of the deployment days, showing large variations in their measured chemical and optical properties. Our analysis of eight distinct episodes, spanning a wide range of chemical composition, optical properties, and source regions, reveals that at episodes with higher OC/SO2−4 and NO3/SO2−4 composition ratios exhibit lower single scatter albedo at shorter wavelengths (ω405; significantly lower [ω405meas = 0.79±0.06, ω405calc = 0.86±0.01] than predicted by an optical model that assumes constant complex index of refraction with wavelength (an optical model of soot. We attribute this discrepancy to enhanced absorption by organic material. Organic carbon absorption accounts for up to 50% of the measured aerosol absorption at 405 nm for the high OC/SO2−4 episode. Coatings of elemental carbon aerosol cores are hypothesized to increase absorption by factors up to 6 at visible wavelengths. Carbonaceous aerosol absorption can alter global radiative forcing estimates substantially, underscoring the need to understand and predict chemical composition effects on optical properties.

  15. Dependence of aerosol scattering coefficients on relative humidity observed at two coastal sites on the East China Sea: Comparison to remote observations and influence of chemical composition

    Science.gov (United States)

    Kanaya, Y.; Taketani, F.; Irie, H.; Komazaki, Y.; Takashima, H.; Xiaole, P.; Takami, A.; Wang, Z.

    2011-12-01

    We employed an integrating nephelometer equipped with a humidifier (where the relative humidity (RH) was scanned between 40 and 90%) to measure the aerosol scattering coefficients and their dependence on RH at Fukue Island (32.75N, 128.68E), west of Japan, in May 2009 and at Rudong, Jiangsu, China (32.26N, 121.37E) in May/June 2010, aiming at better characterization of optical properties of the regional-scale aerosol pollution over East Asia. The two coastal sites are located east and west of the East China Sea and are separated by about 700 km. The observed scattering coefficients are normalized by the concurrently measured PM2.5 mass concentrations and thereby behaviors of the mass scattering coefficients are discussed. At Fukue, the mass scattering coefficients under the ambient RH conditions were >1.5 times higher than those observed under the dry condition (RH = 40%), suggesting that the RH effect was crucial in determining optical properties under ambient conditions. The coefficients under the ambient RH conditions, rather than the dry values, agreed better with the extinction coefficients determined by MAX-DOAS (Multi-Axis Differential Optical Absorption Spectroscopy) technique based on remote measurements of O4 optical depths. The single-scattering albedo (SSA), estimated in combination to the absorption coefficients determined by a MAAP (Multi-Angle Absorption Photometer) instrument, had similar average values (~0.95) at the two sites. The SSA values at the two sites were commonly lowered (to below 0.90) when the air traveled from the North China Plain region. At Fukue, the RH dependence was found to be weakened when the organics/sulfate ratio increased (as observed by an Aerodyne Aerosol Mass Spectrometer), while such influence of chemical composition was less clear at Rudong, possibly masked by large temporal variations in the particle size distributions.

  16. EXPLORING ANTICORRELATIONS AND LIGHT ELEMENT VARIATIONS IN NORTHERN GLOBULAR CLUSTERS OBSERVED BY THE APOGEE SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Mészáros, Szabolcs [ELTE Gothard Astrophysical Observatory, H-9704 Szombathely, Szent Imre Herceg st. 112 (Hungary); Martell, Sarah L. [Department of Astrophysics, School of Physics, University of New South Wales, Sydney, NSW 2052 (Australia); Shetrone, Matthew [University of Texas at Austin, McDonald Observatory, Fort Davis, TX 79734 (United States); Lucatello, Sara [INAF-Osservatorio Astronomico di Padova, vicolo dell Osservatorio 5, I-35122 Padova (Italy); Troup, Nicholas W.; Pérez, Ana E. García; Majewski, Steven R. [Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325 (United States); Bovy, Jo [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States); Cunha, Katia [University of Arizona, Tucson, AZ 85719 (United States); García-Hernández, Domingo A.; Prieto, Carlos Allende [Instituto de Astrofísica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain); Overbeek, Jamie C. [Department of Astronomy, Indiana University, Bloomington, IN 47405 (United States); Beers, Timothy C. [Department of Physics and JINA Center for the Evolution of the Elements, University of Notre Dame, Notre Dame, IN 46556 (United States); Frinchaboy, Peter M. [Texas Christian University, Fort Worth, TX 76129 (United States); Hearty, Fred R.; Schneider, Donald P. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Holtzman, Jon [New Mexico State University, Las Cruces, NM 88003 (United States); Nidever, David L. [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Schiavon, Ricardo P. [Astrophysics Research Institute, IC2, Liverpool Science Park, Liverpool John Moores University, 146 Brownlow Hill, Liverpool, L3 5RF (United Kingdom); and others

    2015-05-15

    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. We derive abundances of 9 elements (Fe, C, N, O, Mg, Al, Si, Ca, and Ti) for 428 red giant stars in 10 GCs. 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, which we take as evidence that low metallicity, intermediate mass AGB polluters were more common in the more metal-poor clusters. The statistically significant correlation of [Al/Fe] with [Si/Fe] in M15 suggests that {sup 28}Si leakage has occurred in this cluster. We also present C, N, and O abundances for stars cooler than 4500 K and examine the behavior of A(C+N+O) in each cluster as a function of temperature and [Al/Fe]. The scatter of A(C+N+O) is close to its estimated uncertainty in all clusters and independent of stellar temperature. A(C+N+O) exhibits small correlations and anticorrelations with [Al/Fe] in M3 and M13, but we cannot be certain about these relations given the size of our abundance uncertainties. Star-to-star variations of α-element (Si, Ca, Ti) abundances are comparable to our estimated errors in all clusters.

  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. Aerosol chemical composition at Cabauw, the Netherlands as observed in two intensive periods in May 2008 and March 2009

    NARCIS (Netherlands)

    Mensah, A.A.; Holzinger, R.; Otjes, R.; Trimborn, A.; Mentel, T.F.; Brink, H. ten; Henzing, B.; Kiendler-Scharr, A.

    2012-01-01

    Observations of aerosol chemical composition in Cabauw, the Netherlands, are presented for two intensive measurement periods in May 2008 and March 2009. Sub-micron aerosol chemical composition was measured by an Aerodyne Aerosol Mass Spectrometer (AMS) and is compared to observations from aerosol si

  19. Variations in backscatter observed in PMMA whole-body dosimetry slab phantoms.

    Science.gov (United States)

    Schwahn, Scott O; Gesell, Thomas F

    2008-01-01

    Polymethyl methacrylate (PMMA) is a useful material for dosimetry phantoms in many ways including approximate tissue equivalence, stability, accessibility and ease of use. However, recent studies indicate that PMMA may have some unanticipated variation in backscatter from one phantom to another. While the reasons behind the variations have not been identified, it has been demonstrated that the backscatter from one phantom to another may vary by as much as 15%, resulting in a dosemeter response variation of as much as 5%. This unexpected contribution to uncertainty in delivered dose to a dosemeter may be quite large compared to the normally estimated uncertainty, potentially causing problems with calibration and performance testing. This paper includes data supporting the differences in backscatter among phantoms, and results from tests on the phantoms performed in an effort to identify possible causes.

  20. Temporal variation of microbiological and chemical quality of noncarbonated bottled drinking water sold in Sri Lanka.

    Science.gov (United States)

    Herath, A T; Abayasekara, C L; Chandrajith, Rohana; Adikaram, N K B

    2012-03-01

    Use of bottled water in Sri Lanka has increased over the last decade, while new brands of bottled water are often introduced to the market. However, the manufacturers' adherence to bottled water regulations is questionable, raising concerns regarding the quality of bottled water. The objective of the current study was to investigate the microbiological and chemical quality of bottled water in Sri Lanka. Thirty bottled water brands were sampled and their chemical and microbiological parameters were analyzed. Microbiological analysis was carried out within 1 to 3, 3 to 6, 6 to 9, and 9 to 12 mo after the date of manufacture. The results indicated that 63% of brands tested exceeded the levels permitted by the Sri Lanka Standards Institution (SLSI) for presumptive total coliforms (TC) (bottled drinking water. Throughout their shelf life, the counts of TC, FC, and HPC bacteria decreased. Bacteria identified were Klebsiella pneumoniae ssp. pneumoniae, Enterobacter cloacae, Pseudomonas aeruginosa, and Pasteurella haemolytica, the most frequently being P. aeruginosa. The dominant fungi identified were Aspergillus sp. and Penicillium sp. Inorganic chemical parameters were within permitted levels for all brands except for initial content of ammonia. The results of this study show the need for the bottling industry to be monitored closely by relevant authorities, in order to provide safe bottled drinking water to consumers in Sri Lanka.

  1. 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

  2. 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

  3. Interannaul variations of the vertical and their possible influence on the star catalogs derived from ground-based astrometric observations

    Science.gov (United States)

    Li, Z. X.

    The efforts at Shanghai Observatory since 1991, in response to the Resolution of IAU Comm.19: "Applications of optical astrometry time and latitude programs", is described in the paper, especially the studies concerned with the interannual variations of the vertical and their influence on the astronomical studies. It is clear now that there is a component of the order 0.01 - 0.02" on an interannual time scale in latitude residuals which is correlated with geophysical phenomena on the Earth. A recent study has confirmed that the component discovered is actually the variation of the vertical, related to ground-based observation in astronomy. So, it should be emphasized now that the variation of the vertical is significant enough to be considered in astronomy from now on. Its influence on the past studies, including the star catalogs already published and the ERP before 1980 when optical astrometry observations were still used, should be studied in the future. In comparing the HIPPARCOS catalog with those derived by the past observations, we should keep in mind the existence of this error in an astrometric observation and its influence on the star catalogs and other results derived from ground-based astrometric observations.

  4. 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.

  5. Interaction between measurement time and observed Hugoniot cusp due to chemical reactions

    Science.gov (United States)

    McGrane, S. D.; Brown, K. E.; Bolme, C. A.; Moore, D. S.

    2017-01-01

    Chemistry occurring on picosecond timescales can be observed through ultrafast laser shock drive experiments that measure Hugoniot data and transient absorption. The shock stress needed to induce chemical reactions on picosecond time scales is significantly larger than the stress needed to induce reactions on nanosecond time scales typical of gas gun and explosively driven plate impact experiments. This discrepancy is consistent with the explanation that increased shock stress leads to increased temperature, which drives thermally activated processes at a faster rate. While the data are qualitatively consistent with the interpretation of thermally dominated reactions, they are not a critical test of this interpretation. In this paper, we review data from several shocked liquids that illustrate a Hugoniot cusp due to volume changing reactions that occurs at higher shock stress states in picosecond experiments than in nanosecond to microsecond experiments. We also correlate the observed Hugoniot cusp states with transient absorption changes that occur due to the buildup of reaction products.

  6. Variation of fundamental constants in space and time: theory and observations

    CERN Document Server

    Flambaum, V V

    2008-01-01

    Review of recent works devoted to the temporal and spatial variation of the fundamental constants and dependence of the fundamental constants on the gravitational potential (violation of local position invariance) is presented. We discuss the variation of the fine structure constant $\\alpha=e^2/\\hbar c$, strong interaction and fundamental masses (Higgs vacuum), e.g. the electron-to-proton mass ratio $\\mu=m_e/M_p$ or $X_e=m_e/\\Lambda_{QCD}$ and $X_q=m_q/\\Lambda_{QCD}$. We also present new results from Big Bang nucleosynthesis and Oklo natural nuclear reactor data and propose new measurements of enhanced effects in atoms, nuclei and molecules, both in quasar and laboratory spectra.

  7. Recent laboratory and field observations of the chemical composition of atmospheric nanoparticles

    Science.gov (United States)

    Smith, J. N.; Winkler, P.; Hildebrandt Ruiz, L.; Lawler, M. J.; Ortega, J.; Fry, J.; Barsanti, K. C.; McMurry, P. H.; Johnston, M. V.

    2012-12-01

    This presentation will focus on understanding the species and mechanisms that are responsible for the formation and growth of atmospheric nanoparticles. We report 10 - 40 nm diameter nanoparticle chemical composition measurements performed in two coastal sites (Mace Head, Ireland, and Lewes, Delaware USA) and two forested sites (Hyytiälä, Finland, and Manitou Forest, Colorado USA) with the recently-developed High Resolution Time-of-Flight Thermal Desorption Chemical Ionization Mass Spectrometer (HTOF-TDCIMS). These field measurements are supplemented by laboratory experiments of particle formation and growth performed at NCAR using a flow tube apparatus and a Teflon bag reaction chamber, and by thermodynamic modeling. Together, our field and laboratory observations point to crucial roles played in nanoparticle growth by two compounds: organic acids and organonitrates. The first, organic acids, are major contributors to the organic fraction in sub-20 nm diameter biogenic nanoparticles but appear to be less abundant in the organic fraction of larger particles, the latter of which are dominated by multifunctional carbonyl- and alcohol-containing compounds. The observed changes in chemical composition of the organic fraction as a function of particle size are supported by thermodynamic modeling results. The second, organonitrates, are commonly found in ambient nanoparticles as small as 10 nm in diameter. However unlike organic acids, organonitrates become increasingly more important in nanoparticle growth as particle size increases. Laboratory experiments suggest that organonitrates formed from the nitrate radical oxidation of biogenic organic compounds, a subset of total organonitrates, exhibit particularly low volatility and can thus partition into the smallest nanoparticles. This is confirmed by HTOF-TDCIMS measurements of 10 - 20 nm diameter particles, which show that particulate phase organonitrates peak in the morning, shortly following the period where

  8. 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.

  9. Chemical isolation in the Asian monsoon anticyclone observed in Atmospheric Chemistry Experiment (ACE-FTS data

    Directory of Open Access Journals (Sweden)

    M. Park

    2008-02-01

    Full Text Available Evidence of chemical isolation in the Asian monsoon anticyclone is presented using chemical constituents obtained from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer instrument during summer (June–August of 2004–2006. Carbon monoxide (CO shows a broad maximum over the monsoon anticyclone region in the upper troposphere and lower stratosphere (UTLS; these enhanced CO values are associated with air pollution transported upward by convection, and confined by the strong anticyclonic circulation. Profiles inside the anticyclone show enhancement of tropospheric tracers CO, HCN, C2H6, and C2H2 between ~12 to 20 km, with maxima near 13–15 km. Strong correlations are observed among constituents, consistent with sources from near-surface pollution and biomass burning. Stratospheric tracers (O3, HNO3 and HCl exhibit decreased values inside the anticyclone between ~12–20 km. These observations are further evidence of transport of lower tropospheric air into the UTLS region, and isolation of air within the anticyclone. The relative enhancements of tropospheric species inside the anticyclone are closely related to the photochemical lifetime of the species, with strongest enhancement for shorter lived species. Vertical profiles of the ratio of C2H2/CO (used to measure the relative age of air suggest relatively rapid transport of fresh emissions up to the tropopause level inside the anticyclone.

  10. Chemical Isolation in the Asian monsoon anticyclone observed in Atmospheric Chemistry Experiment (ACE-FTS data

    Directory of Open Access Journals (Sweden)

    M. Park

    2007-09-01

    Full Text Available Evidence of chemical isolation in the Asian monsoon anticyclone is presented using chemical constituents obtained from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer instrument during summer (June–August of 2004–2006. Carbon monoxide (CO shows a broad maximum over the monsoon anticyclone region in the upper troposphere and lower stratosphere (UTLS; these enhanced CO values are associated with air pollution transported upward by convection, and confined by the strong anticyclonic circulation. Profiles inside the anticyclone show enhancement of tropospheric tracers CO, HCN, C2H6, and C2H2 between ~12 to 20 km, with maxima near 13–15 km. Strong correlations are observed among constituents, consistent with sources from near-surface pollution and biomass burning. Stratospheric tracers (O3, HNO3 and HCl exhibit decreased values inside the anticyclone between ~12–20 km. These observations are further evidence of transport of lower tropospheric air into the UTLS region, and isolation of air within the anticyclone. The relative enhancements of tropospheric species inside the anticyclone are closely related to the photochemical lifetime of the species, with strongest enhancement for shorter lived species. Vertical profiles of the ratio of C2H2/CO (used to measure the relative age of air suggest relatively rapid transport of fresh emissions up to tropopause level inside the anticyclone.

  11. 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 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...

  12. A case for variational geomagnetic data assimilation: insights from a one-dimensional, nonlinear, and sparsely observed MHD system

    CERN Document Server

    Fournier, Alexandre; Alboussière, Thierry

    2007-01-01

    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 pape...

  13. Variation in chemical, colloidal and electrochemical properties of carbon nanotubes with the degree of carboxylation

    Science.gov (United States)

    Wu, Zheqiong; Wang, Zhiqian; Yu, Fang; Thakkar, Megha; Mitra, Somenath

    2017-01-01

    Multiwalled carbon nanotubes (CNTs) were carboxylated via microwave irradiation where the treatment time was varied to alter the degree of functionalization, and as many as one in 15 carbons in the CNT could be oxidized. Chemical, physical, electrochemical, and colloidal behavior of the carboxylated CNTs was studied. All properties changed with the degree of functionalization to a point beyond which they appeared to remain constant. The surface area increased from 173.9 to 270.9 m2/g while the critical coagulation concentration (CCC) values increased from 142.14 to 168.69 mM in the presence of NaCl, and the corresponding increase was from 0.97 to 5.32 mM in the presence of MgCl2. As seen from cyclic voltammetry curves, the functionalized CNTs showed mainly non-Faradic interactions with Na2SO4, but showed Faradic behaviors in alkaline KOH.

  14. Chemical variation of tannins and triterpenes in Brazilian populations of Maytenus ilicifolia Mart. Ex Reiss

    Directory of Open Access Journals (Sweden)

    AJ. Mossi

    Full Text Available Maytenus ilicifolia and Maytenus aquifolia species are widely used as a cicatrisation agent, an anti-spasmodic, contraceptive, antiulcerogenic, diuretic and analgesic. Considering the importance of these species in popular medicine, this work is focused on the determination of the chemical content of tannins and the triterpenes friedelan-3-one, friedelan-3-ol and friedelin in 15 native populations of Maytenus ilicifolia distributed in the south and mind-west regions of Brazil. Correlation of the concentration of these compounds with the environmental parameters such as average annual temperature, climate, vegetation, geomorphology, latitude and altitude was determined using Pearson's coefficient. Results showed that average annual temperature and climate have significant effect on tannin content at a 95% confidence level. The highest tannin concentration was found in Ponta Porã population, and for the triterpenes investigated, a significant correlation between their concentrations with the environmental variables studied was not verified.

  15. 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 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.

  16. VARIATION OF PHYSICO-CHEMICAL PROPERTIES OF RADIATION CROSSLINKED RUBBER WITH STORAGE TIME

    Institute of Scientific and Technical Information of China (English)

    N.C. Dafader; M.E. Haque; F. Akhtar

    2005-01-01

    The effect of storage on physico-chemical properties of non-irradiated natural rubber and radiation vulcanized natural rubber (RVNR) were evaluated. The rubber films were stored under two different conditions, namely in open air and sealed polyethylene bags. The antioxidant, tris(nonylated phenyl) phosphite (TNPP) was used for preventing degradation of RVNR films. Gel content, cross-link density, tensile strength at break and 500% elongation of rubber films were measured.The results show that the retention (%) of tensile properties of rubber films with TNPP is higher than that of rubber films without antioxidants. The rubber films stored in polyethylene bags also show better retention of tensile properties than those of rubber films stored in open air.

  17. Ontogenetic variation in chemical and physical characteristics of adaxial apple leaf surfaces.

    Science.gov (United States)

    Bringe, Katja; Schumacher, Christina F A; Schmitz-Eiberger, Michaela; Steiner, Ulrike; Oerke, Erich-Christian

    2006-01-01

    The reaction of plants to environmental factors often varies with developmental stage. It was hypothesized, that also the cuticle, the outer surface layer of plants is modified during ontogenesis. Apple plantlets, cv. Golden Delicious, were grown under controlled conditions avoiding biotic and abiotic stress factors. The cuticular wax surface of adaxial apple leaves was analyzed for its chemical composition as well as for its micromorphology and hydrophobicity just after unfolding of leaves ending in the seventh leaf insertion. The outer surface of apple leaves was formed by a thin amorphous layer of epicuticular waxes. Epidermal cells of young leaves exhibited a distinctive curvature of the periclinal cell walls resulting in an undulated surface of the cuticle including pronounced lamellae, with the highest density at the centre of cells. As epidermal cells expanded during ontogenesis, the upper surface showed only minor surface sculpturing and a decrease in lamellae. With increasing leaf age the hydrophobicity of adaxial leaf side decreased significantly indicated by a decrease in contact angle. Extracted from plants, the amount of apolar cuticular wax per area unit ranged from only 0.9 microgcm(-2) for the oldest studied leaf to 1.5 microgcm(-2) for the youngest studied leaf. Differences in the total amount of cuticular waxes per leaf were not significant for older leaves. For young leaves, triterpenes (ursolic acid and oleanolic acid), esters and alcohols were the main wax components. During ontogenesis, the proportion of triterpenes in total mass of apolar waxes decreased from 32% (leaf 1) to 13% (leaf 7); absolute amounts decreased by more than 50%. The proportion of wax alcohols and esters, and alkanes to a lesser degree, increased with leaf age, whereas the proportion of acids decreased. The epicuticular wax layer also contained alpha-tocopherol described for the first time to be present also in the epicuticular wax. The modifications in the chemical

  18. The seasonal variation of the chemical composition of essential oils from Porcelia macrocarpa R.E. Fries (Annonaceae) and their antimicrobial activity.

    Science.gov (United States)

    da Silva, Erica Biolcati P; Soares, Marisi G; Mariane, Bruna; Vallim, Marcelo A; Pascon, Renata C; Sartorelli, Patricia; Lago, João Henrique G

    2013-11-01

    This study investigates the impact of seasonal variation on the chemical composition of essential oils from the leaves of Porcelia macrocarpa (Annonaceae) obtained over the course of one year (January-December 2011) and the chemical composition of the essential oils obtained from the ripe fruits of the same plant. Furthermore, the essential oils of the leaves were investigated with respect to their antimicrobial activity. The essential oils of the leaves contain a mixture of monoterpenes, one diterpene and several sesquiterpenes. The main components were identified as the sesquiterpenes germacrene D (29%-50%) and bicyclogermacrene (24%-37%). No significant variation was observed for the composition of the essential oil of the leaves over the course of the year, except for the month of November, when the ripe fruit were collected. In this month, substantially decreased concentrations of germacrene D (28.8 ± 0.8%) and bicyclogermacrene (23.9 ± 0.6%) were measured and the emergence of spathulenol (10.4 ± 0.2%) was observed. The essential oils extracted from the ripe fruit revealed the presence of a variety of monoterpenes, sesquiterpenes and hydrocarbons. The main constituents of these oils were neryl (8.8 ± 0.2%) and geranyl (27.3 ± 0.7%) formates, γ-muurolene (10.3 ± 0.9%) and dendrolasin (8.23 ± 0.06%). The antimicrobial activity of the essential oil obtained from the leaves of P. macrocarpa towards a range of bacterial and yeast strains was examined. In order to determine the minimum inhibitory concentration (MIC) of essential oils obtained from the January collection of the leaves, broth microdilution assays were carried out, which showed a significant antimicrobial activity towards Cryptococcus neoformans serotypes A and D as well as C. gattii serotypes B and C.

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

    Science.gov (United States)

    Lynch, Tim P; Morello, Elisabetta B; Evans, Karen; Richardson, Anthony J; Rochester, Wayne; Steinberg, Craig R; Roughan, Moninya; Thompson, Peter; Middleton, John F; Feng, Ming; Sherrington, Robert; Brando, Vittorio; Tilbrook, Bronte; Ridgway, Ken; Allen, Simon; Doherty, Peter; Hill, Katherine; Moltmann, Tim C

    2014-01-01

    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.

  20. 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.

  1. IMOS National Reference Stations: A Continental-Wide Physical, Chemical and Biological Coastal Observing System

    Science.gov (United States)

    Lynch, Tim P.; Morello, Elisabetta B.; Evans, Karen; Richardson, Anthony J.; Rochester, Wayne; Steinberg, Craig R.; Roughan, Moninya; Thompson, Peter; Middleton, John F.; Feng, Ming; Sherrington, Robert; Brando, Vittorio; Tilbrook, Bronte; Ridgway, Ken; Allen, Simon; Doherty, Peter; Hill, Katherine; Moltmann, Tim C.

    2014-01-01

    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. PMID:25517905

  2. 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

  3. Variation in the chemical composition of cone volatiles within the African cycad genus Encephalartos.

    Science.gov (United States)

    Suinyuy, Terence N; Donaldson, John S; Johnson, Steven D

    2013-01-01

    Volatiles play a key role in attraction of pollinators to cycad cones, but the extent to which volatile chemistry varies among cycad species is still poorly documented. Volatile composition of male and female cones of nineteen African cycad species (Encephalartos; Zamiaceae) was analysed using headspace technique and gas chromatography-mass spectrometry (GC-MS). A total of 152 compounds were identified among the species included in this study, the most common of which were monoterpenes, nitrogen-containing compounds and unsaturated hydrocarbons. Male and female cones emitted similar volatile compounds which varied in relative amounts with two unsaturated hydrocarbons (3E)-1,3-octadiene and (3E,5Z)-1,3,5-octatriene present in the volatile profile of most species. In a multivariate analysis of volatile profiles using non-metric multidimensional scaling (NMDS), a number of species clusters were identified according to shared emission of unsaturated hydrocarbons, pyrazines, benzenoids, aldehydes, alkanes and terpenoids. In comparison, terpenoids are common in Zamia and dominant in Macrozamia species (both in the family Zamiaceae) while benzenoids, esters, and alcohols are dominant in Cycas (Cycadaceae) and in Stangeria (Stangeriaceae). It is likely that volatile variation among Encephalartos species reflects both phylogeny and adaptations to specific beetle pollinators.

  4. 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.

  5. Dust variations in the diffuse interstellar medium: constraints on Milky Way dust from Planck-HFI observations

    CERN Document Server

    Ysard, N; Jones, A; Miville-Deschênes, M -A; Abergel, A; Fanciullo, L

    2015-01-01

    The Planck-HFI all-sky survey from 353 to 857GHz combined with the 100 microns IRAS show that the dust properties vary in the diffuse ISM at high Galactic latitude (1e19variations with changes in the ISM properties and grain evolution. Our starting point is the latest core-mantle dust model. It consists of small aromatic-rich carbon grains, larger amorphous carbon grains with aliphatic-rich cores and aromatic-rich mantles, and amorphous silicates with Fe/FeS nano-inclusions covered by aromatic-rich carbon mantles. We explore whether variations in the radiation field or in the gas density distribution in the diffuse ISM could explain the observations. The dust properties are also varied in terms of mantle thickness, Fe/FeS inclusions, carbon abundance, and size distribution. Variations in the radiation field intensity and gas density distribution cannot explain the observed variations but radiation fields harder than the standard ISRF may participate in crea...

  6. Variations of the spectral index of dust emissivity from Hi-GAL observations of the Galactic plane

    CERN Document Server

    Paradis, D; Noriega-Crespo, A; Paladini, R; Piacentini, F; Bernard, J P; de Bernardis, P; Calzoletti, L; Faustini, F; Martin, P; Masi, S; Montier, L; Natoli, P; Ristorcelli, I; Thompson, M A; Traficante, A; Molinari, S

    2010-01-01

    Variations in the dust emissivity are critical for gas mass determinations derived from far-infrared observations, but also for separating dust foreground emission from the Cosmic Microwave Background (CMB). Hi-GAL observations allow us for the first time to study the dust emissivity variations in the inner regions of the Galactic plane at resolution below 1 degree. We present maps of the emissivity spectral index derived from the combined Herschel PACS 160 \\mu m, SPIRE 250 \\mu m, 350 \\mu m, and 500 \\mu m data, and the IRIS 100 \\mu m data, and we analyze the spatial variations of the spectral index as a function of dust temperature and wavelength in the two Science Demonstration Phase Hi-GAL fields, centered at l=30{\\deg} and l=59{\\deg}. Applying two different methods, we determine both dust temperature and emissivity spectral index between 100 and 500 \\mu m, at an angular resolution of 4'. Combining both fields, the results show variations of the emissivity spectral index in the range 1.8-2.6 for temperature...

  7. 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

  8. Surface variations affecting human dental enamel studied using nanomechanical and chemical analysis

    Science.gov (United States)

    Dickinson, Michelle Emma

    The enamel surface is the interface between the tooth and its ever changing oral environment. Cavity (caries) formation and extrinsic tooth staining are due, respectively, to degradation of the enamel structure under low pH conditions and interactions between salivary pellicle and dietary elements. Both of these occur at the enamel surface and are caused by the local environment changing the chemistry of the surface. The results can be detrimental to the enamel's mechanical integrity and aesthetics. Incipient carious lesions are the precursor to caries and form due to demineralisation of enamel. These carious lesions are a reversible structure where ions (e.g. Ca2+, F -) can diffuse in (remineralisation) to preserve the tooth's structural integrity. This investigation used controlled in vitro demineralisation and remineralisation to study artificial carious lesion formation and repair. The carious lesions were cross-sectioned and characterised using nanoindentation, electron probe micro-analysis and time of flight secondary ion mass spectrometry. Mechanical and chemical maps showed the carious lesion had a significantly reduced hardness and elastic modulus, and the calcium and phosphate content was lower than in sound enamel. Fluoride based remineralisation treatments gave a new phase (possibly fluorohydroxyapatite) within the lesion with mechanical properties higher than sound enamel. The acquired salivary pellicle is a protein-rich film formed by the physisorption of organic molecules in saliva onto the enamel surface. Its functions include lubrication during mastication and chemical protection. However, pellicle proteins react with dietary elements such as polyphenols (tannins in tea) causing a brown stain. This study has used in vitro dynamic nanoindentation and atomic force microscopy to examine normal and stained pellicles formed in vivo. The effects of polyphenols on the pellicle's mechanical properties and morphology have been studied. It was found that the

  9. Variation of fundamental constants in space and time: Theory and observations

    Science.gov (United States)

    Flambaum, V. V.

    2008-10-01

    Review of recent works devoted to the temporal and spatialvariation of the fundamental constants and dependence of the fundamentalconstants on the gravitational potential (violation of local position invariance) is presented. We discuss the variation of the fine structure constant α=e2/ħc, strong interaction andfundamental masses (Higgs vacuum), e.g. the electron-to-proton mass ratioμ=me/Mp or Xe=me/ΛQCD and Xq=mq/ΛQCD.We also present new results from Big Bang nucleosynthesisand Oklo natural nuclear reactor data and propose new measurements of enhanced effects in atoms, nuclei and molecules, both in quasar and laboratory spectra.

  10. Notable seasonal variation observed in the morphology of the reindeer rumen fluke (Paramphistomum leydeni in Finland

    Directory of Open Access Journals (Sweden)

    Sven Nikander

    2009-01-01

    Full Text Available Although numerous Paramphistomum species have been described from the rumen and reticulum of domestic and wild ruminants, information about rumen flukes in reindeer is sparse and their nomenclature is somewhat conflicting. Rumen fluke of reindeer is usually referred to as P. cervi, but P. leydeni and Cotylophoron skriabini are also mentioned in the literature. Here, the surface structures and internal anatomy of rumen flukes from reindeer, as seen by scanning electron microscopy (SEM and in histological sections under light microscopy, are presented. The aim of the study was to find morphological information to enable identification of rumen flukes in reindeer to species level. In addition, the morphology of rumen flukes collected in winter (winter flukes was compared with that of flukes collected in summer (summer flukes. Key morphological findings were as follows: the acetabulum of the rumen flukes was of paramphistomum type, the pharynx of liorchis type, and the genital atrium of leydeni type. Both winter and summer flukes shared these morphological features. Based on these findings, it was concluded that rumen flukes of reindeer in Finland belonged to the species P. leydeni. Significant morphological variation was observed when winter and summer flukes were compared. The winter fluke was smaller in size, possessed immature gonads (testes, ovary, uterus, and immature accessory genital glands (Mehlis’ gland, vitelline follicles, and had barely discernible tegumental papillae. These data indicate that winter rumen flukes represent an immature stage of P. leydeni and summer flukes the mature stage of the same species. Further, these findings suggest that the rumen flukes of reindeer during wintertime in Finland have a slowed or inhibited lifecycle.Abstract in Finnish / Yhteenveto:Poron pötsimadon (Paramphistomum leydeni morfologiassa esiintyy selvää vuodenaikaisvaihtelua Pötsimatoja (Paramphistomum spp. löytyy monien villien ja kotiel

  11. Control of nanoparticle agglomeration through variation of the time-temperature profile in chemical vapor synthesis

    Science.gov (United States)

    Djenadic, Ruzica; Winterer, Markus

    2017-02-01

    The influence of the time-temperature history on the characteristics of nanoparticles such as size, degree of agglomeration, or crystallinity is investigated for chemical vapor synthesis (CVS). A simple reaction-coagulation-sintering model is used to describe the CVS process, and the results of the model are compared to experimental data. Nanocrystalline titania is used as model material. Titania nanoparticles are generated from titanium-tetraisopropoxide (TTIP) in a hot-wall reactor. Pure anatase particles and mixtures of anatase, rutile (up to 11 vol.%), and brookite (up to 29 vol.%) with primary particle sizes from 1.7 nm to 10.5 nm and agglomerate particle sizes from 24.3 nm to 55.6 nm are formed depending on the particle time-temperature history. An inductively heated furnace with variable inductor geometry is used as a novel system to control the time-temperature profile in the reactor externally covering a large wall temperature range from 873 K to 2023 K. An appropriate choice of inductor geometry, i.e. time-temperature profile, can significantly reduce the degree of agglomeration. Other particle characteristics such as crystallinity are also substantially influenced by the time-temperature profile.

  12. Seasonal and diurnal hydro-chemical variations in a recreated reed bed

    Directory of Open Access Journals (Sweden)

    C. J. Stratford

    2004-01-01

    Full Text Available To help stem this decline, wetland areas are now being preserved and where possible created. This study investigated water quality in a recreated reed bed in south-west England designed specifically to provide habitat for birds. Since June 2000, continuous measurements of temperature, pH, electrical conductivity and dissolved oxygen have been logged. These data enable the partial pressure of CO2 to be calculated. This paper looks at the data collected up to November 2001. Despite similar solar radiation and water temperature conditions in both 2000 and 2001, peak summertime values of dissolved oxygen dropped from >100% to 2 increased from 19.7 to 56.1. Analysis of the diurnal dissolved oxygen curves indicates a decrease in photosynthesis which, in the absence of a change in nutrient concentrations in the water, may result from surface plant growth or from a reduction in submerged plant cover. The implications of these changing hydro-chemical conditions are that the site will be less able to support such a wide diversity of aquatic fauna, which will reduce the effectiveness of the site as a habitat for some bird species. Keywords: wetland, reed bed, hydrochemistry, dissolved oxygen, pH, continuous monitoring, Hamwall, Somerset Levels

  13. 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.

  14. Observation of spatial and temporal variations in X-ray bright point emergence patterns. [at solar surface

    Science.gov (United States)

    Golub, L.; Krieger, A. S.; Vaiana, G. S.

    1976-01-01

    Observations of X-ray bright points (XBP) over a six-month interval in 1973 show significant variations in both the number density of XBP as a function of heliographic longitude and in the full-sun average number of XBP from one rotation to the next. The observed increases in XBP emergence are estimated to be equivalent to several large active regions emerging per day for several months. The number of XBP emerging at high latitudes varies in phase with the low-latitude variation and reaches a maximum approximately simultaneous with a major outbreak of active regions. The quantity of magnetic flux emerging in the form of XBP at high latitudes alone is estimated to be as large as the contribution from all active regions.

  15. Effect of chemical composition variation on microstructure and mechanical properties of a 6060 aluminum alloy

    Science.gov (United States)

    Silva, M. S.; Barbosa, C.; Acselrad, O.; Pereira, L. C.

    2004-04-01

    The 6XXX series aluminum alloys (Al-Mg-Si) are widely used in many different engineering and architectural applications. These alloys usually undergo a thermal treatment, which consists of a heat treatment solution and artificial aging, since the desirable mechanical properties depend on the microstructural state of the material. The recycling of materials has been increasing recently for economic and ecologic reasons. By using scrap was raw material, important reductions in energy and total costs can be achieved, and, at the same time, negative environmental impacts can be greatly reduced. In the present work, the possibility of using a larger amount of scrap as raw material in the production of an AA 6060 alloy is evaluated by analyzing the difference in microstructure and mechanical properties between a commercial 6060 alloy and a variation with higher Fe and lower Si contents that was specially produced for this study. Both materials were placed into a heat treatment solution at 560 °C for 1 h, and then underwent water quenching followed by artificial aging at 180 °C for different periods of time. Hardness and tension tests were used to evaluate the mechanical properties. Light and transmission electron microscopy have been used to determine important features such as grain size before and after being placed into the heat treatment solution, and the characteristics of the second-phase particles in the two materials. This study leads to the conclusion that a higher amount of scrap material can be used in the production of 6060 Al alloy without significant changes in mechanical properties compared with the more usual compositions.

  16. Numerical solution to the problem of variational assimilation of operational observational data on the ocean surface temperature

    Science.gov (United States)

    Agoshkov, V. I.; Lebedev, S. A.; Parmuzin, E. I.

    2009-02-01

    The problem of variational assimilation of satellite observational data on the ocean surface temperature is formulated and numerically investigated in order to reconstruct surface heat fluxes with the use of the global three-dimensional model of ocean hydrothermodynamics developed at the Institute of Numerical Mathematics, Russian Academy of Sciences (INM RAS), and observational data close to the data actually observed in specified time intervals. The algorithms of the numerical solution to the problem are elaborated and substantiated, and the data assimilation block is developed and incorporated into the global three-dimensional model. Numerical experiments are carried out with the use of the Indian Ocean water area as an example. The data on the ocean surface temperature over the year 2000 are used as observational data. Numerical experiments confirm the theoretical conclusions obtained and demonstrate the expediency of combining the model with a block of assimilating operational observational data on the surface temperature.

  17. 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.

  18. 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.

  19. A preliminary estimate of geoid-induced variations in repeat orbit satellite altimeter observations

    Science.gov (United States)

    Brenner, Anita C.; Beckley, B. D.; Koblinsky, C. J.

    1990-01-01

    Altimeter satellites are often maintained in a repeating orbit to facilitate the separation of sea-height variations from the geoid. However, atmospheric drag and solar radiation pressure cause a satellite orbit to drift. For Geosat this drift causes the ground track to vary by + or - 1 km about the nominal repeat path. This misalignment leads to an error in the estimates of sea surface height variations because of the local slope in the geoid. This error has been estimated globally for the Geosat Exact Repeat Mission using a mean sea surface constructed from Geos 3 and Seasat altimeter data. Over most of the ocean the geoid gradient is small, and the repeat-track misalignment leads to errors of only 1 to 2 cm. However, in the vicinity of trenches, continental shelves, islands, and seamounts, errors can exceed 20 cm. The estimated error is compared with direct estimates from Geosat altimetry, and a strong correlation is found in the vicinity of the Tonga and Aleutian trenches. This correlation increases as the orbit error is reduced because of the increased signal-to-noise ratio.

  20. 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...

  1. Linking Informant Discrepancies to Observed Variations in Young Children's Disruptive Behavior

    Science.gov (United States)

    De Los Reyes, Andres; Henry, David B.; Tolan, Patrick H.; Wakschlag, Lauren S.

    2009-01-01

    Prior work has not tested the basic theoretical notion that informant discrepancies in reports of children's behavior exist, in part, because different informants observe children's behavior in different settings. We examined patterns of observed preschool disruptive behavior across varying social contexts in the laboratory and whether they…

  2. The Increasing Prevalence in Intersex Variation from Toxicological Dysregulation in Fetal Reproductive Tissue Differentiation and Development by Endocrine-Disrupting Chemicals

    Science.gov (United States)

    Rich, Alisa L.; Phipps, Laura M.; Tiwari, Sweta; Rudraraju, Hemanth; Dokpesi, Philip O.

    2016-01-01

    An increasing number of children are born with intersex variation (IV; ambiguous genitalia/hermaphrodite, pseudohermaphroditism, etc.). Evidence shows that endocrine-disrupting chemicals (EDCs) in the environment can cause reproductive variation through dysregulation of normal reproductive tissue differentiation, growth, and maturation if the fetus is exposed to EDCs during critical developmental times in utero. Animal studies support fish and reptile embryos exhibited IV and sex reversal when exposed to EDCs. Occupational studies verified higher prevalence of offspring with IV in chemically exposed workers (male and female). Chemicals associated with endocrine-disrupting ability in humans include organochlorine pesticides, poly-chlorinated biphenyls, bisphenol A, phthalates, dioxins, and furans. Intersex individuals may have concurrent physical disorders requiring lifelong medical intervention and experience gender dysphoria. An urgent need exists to determine which chemicals possess the greatest risk for IV and the mechanisms by which these chemicals are capable of interfering with normal physiological development in children. PMID:27660460

  3. Chemical variations in the Cerro de Mercado (Durango, Mexico) fluorapatite: Assessing the effect of heterogeneity on a geochronologic standard.

    Science.gov (United States)

    Boyce, J. W.; Hodges, K. V.

    2001-12-01

    Despite the lack of an official pronouncement, the fluorapatite of Cerro de Mercado, Durango, Mexico has become the de facto standard for (U-Th)/He geochronology. In addition to being relatively inclusion-free and easily obtained, these crystals are commonly in excess of 5mm in diameter, permitting the removal of the outer skin of the crystal, theoretically eliminating the alpha-ejection correction. However, bulk analyses of the Durango fluorapatite indicate a substantial variation in U and Th concentrations from aliquot to aliquot (167-238 ppm Th; 9.7-12.3 ppm U, [1]). If similar variations were to occur on the sub-grain scale, small fragments of single crystals could contain helium excesses or deficiencies due to alpha-ejection exchange between zones with varying parent element content. We have performed a series of experiments to quantify the intra-grain variation in U and Th, in order to model the effect of this variation on ages determined on Durango fluorapatite. X-ray maps show concentric zonation in U and Th, with similar, but more apparently pronounced zonation in Si and Cl. Preliminary laser-ablation ICPMS data indicate, not surprisingly, that intra-grain variations in U and Th concentrations obtained by analysis of ~35 μ m spots are larger than that which had been previously obtained by bulk analytical techniques (with overall concentrations greater than for bulk analyses). Thus far, analyses yield U concentrations varying from 11 to 16 ppm, and Th concentrations ranging from 220 to 340 ppm. Modeling underway suggests that parent element variations on the order of 50%, such as those observed, and the resulting differential alpha-exchange could lead to several percent error in age, for ~100 μ m fragments. The effect scales inversely with fragment size, with 300 μ m fragments (roughly the size of a large, single grain analysis) having only ~1% error. This may offer an explanation for the previously observed inability to reproduce ages for the Durango

  4. 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.

  5. The sensitivity of QBA assessments of sheep behavioural expression to variations in visual or verbal information provided to observers.

    Science.gov (United States)

    Fleming, P A; Wickham, S L; Stockman, C A; Verbeek, E; Matthews, L; Wemelsfelder, F

    2015-05-01

    Qualitative behavioural assessment (QBA) is based on observers' ability to capture the dynamic complexity of an animal's demeanour as it interacts with the environment, in terms such as tense, anxious or relaxed. Sensitivity to context is part of QBA's integrative capacity and discriminatory power; however, when not properly managed it can also be a source of undesirable variability and bias. This study investigated the sensitivity of QBA to variations in the visual or verbal information provided to observers, using free-choice profiling (FCP) methodology. FCP allows observers to generate their own descriptive terms for animal demeanour, against which each animal's expressions are quantified on a visual analogue scale. The resulting scores were analysed with Generalised Procrustes Analysis (GPA), generating two or more multi-variate dimensions of animal expression. Study 1 examined how 63 observers rated the same video clips of individual sheep during land transport, when these clips were interspersed with two different sets of video footage. Scores attributed to the sheep in the two viewing sessions correlated significantly (GPA dimension 1: r s =0.95, Pobservers assessing footage of 22 individual sheep in a behavioural demand facility. One group was given no contextual information regarding this facility, whereas the second group was told that animals were moving towards and away from a feeder (in view) to access feed. Scores attributed to individual sheep by the two observer groups correlated significantly (Dim1: r s =0.92, Pobserver groups and used in similar ways, other terms were unique to each group. The group given additional information about the experimental facility scored the sheep's behaviour as more 'directed' and 'focused' than observers who had not been told. Thus, in neither of the two studies did experimentally imposed variations in context alter the characterisations of animals relative to each other, but in Study 1 this did affect the mean

  6. Wetting of potassium surfaces by superfluid 4He: A study using variational properties of the chemical potential

    Science.gov (United States)

    Szybisz, Leszek

    2000-08-01

    The wetting of planar surfaces of K by superfluid 4He films at T=0 K is theoretically studied. In order to examine the consistency of numerical results, new variational properties of the chemical potential μ are derived. Two substrate-adsorbate interactions are analyzed: (a) the standard ``3-9'' one and (b) the more elaborated potential recently proposed by Chizmeshya, Cole, and Zaremba (CCZ). New results calculated within the framework of two different nonlocal density functionals (namely, those known as the Orsay-Paris and Orsay-Trento formalisms) are reported. It is demonstrated that the numerical solutions obtained from the theoretical equations verify with high accuracy the derived variational conditions. The main output of this investigation is the finding that, for both analyzed adsorption potentials, thick enough helium films exhibit a positive square of the third-sound velocity. The wetting of a potassium substrate by superfluid 4He at T=0 K suggested by experimental data is guaranteed in the case of the recent CCZ potential.

  7. Length Variations of European Baselines Derived from VLBI and GPS Observations

    CERN Document Server

    Malkin, Zinovy; Skurikhina, Elena

    2011-01-01

    Results of VLBI and GPS observations were analyzed with goal to investigate differences in observed baseline length derived from both techniques. VLBI coordinates for European stations were obtained from processing of all available observations collected on European and global VLBI network. Advanced model for antenna thermal deformation was applied to account for change of horizontal component of baseline length. GPS data were obtained from re-processing of the weekly EPN (European Permanent GPS Network) solutions. Systematic differences between results obtained with two techniques including linear drift and seasonal effects are determined.

  8. [Measurement of the wound cavity area by means of PC based planimetry. The method and observer variations].

    Science.gov (United States)

    Andersen, J; Dahlin, J

    1993-03-01

    A method for wound area measurement is presented. A wound cavity was cut in a chine of pork. A thin PVC plastic film was applied closely to the entire wound cavity surface and a line was drawn close to the cutaneous border with a marker pen. The film was then placed on a system of coordinates and coordinates were determined and entered into a PC-programme which calculated the area. No significant intra-or inter-observer variation appeared on analyses of variance between five observers each of whom performed three consecutive measurements (p > 0.2). Thus, employment of the method for clinical purposes seems feasible.

  9. Interpreting the variations in atmospheric methane fluxes observed above a restored wetland

    DEFF Research Database (Denmark)

    Herbst, Mathias; Friborg, Thomas; Ringgaard, Rasmus;

    2011-01-01

    The eddy flux of methane (CH4) was measured over 14 months above a restored wetland in western Denmark. The average annual daily CH4 flux was 30.2mgm-2 d-1, but the daily emission rates varied considerably over time. Several factors were identified that explained some of this variation. (1) Grazing...... cattle moving through the source area of the eddy flux mast increased the measured emission rates by one order of magnitude during short time periods. (2) Friction velocity exerted a strong control on the CH4 flux whenever there were water pools on the surface. (3) An exponential response of the daily CH...... of the source area. This area covered not only different plant communities but also a gravel road and a river surface, and it had a microtopography that visibly induced a large spatial variability in the wetness of the top soil. It is shown that the control mechanisms for the methane emission from restored...

  10. 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.

  11. Ab Initio Calculations of 31P NMR Chemical Shielding Anisotropy Tensors in Phosphates: Variations Due to Ring Formation

    Directory of Open Access Journals (Sweden)

    Todd M. Alam

    2002-08-01

    Full Text Available Abstract: Ring formation in phosphate systems is expected to influence both the magnitude and orientation of the phosphorus (31P nuclear magnetic resonance (NMR chemical shielding anisotropy (CSA tensor. Ab initio calculations of the 31P CSA tensor in both cyclic and acyclic phosphate clusters were performed as a function of the number of phosphate tetrahedral in the system. The calculation of the 31P CSA tensors employed the GAUSSIAN 98 implementation of the gauge-including atomic orbital (GIAO method at the Hartree-Fock (HF level. It is shown that both the 31P CSA tensor anisotropy, and the isotropic chemical shielding can be used for the identification of cyclic phosphates. The differences between the 31P CSA tensor in acyclic and cyclic phosphate systems become less pronounced with increasing number of phosphate groups within the ring. The orientation of the principal components for the 31P CSA tensor shows some variation due to cyclization, most notably with the smaller, highly strained ring systems.

  12. 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.

  13. The solar eclipse and associated atmospheric variations observed in South Korea on 22 July 2009.

    Science.gov (United States)

    Chung, Yong Seung; Kim, Hak Sung; Choo, Seung Ho

    2010-09-01

    A partial solar eclipse occurred in South Korea on 22 July 2009. It started at 09:30 a.m. and lasted until 12:14 LST with coverage of between 76.8% and 93.1% of the sun. The observed atmospheric effects of the eclipse are presented. It was found that from the onset of the eclipse, solar radiation was reduced by as much as 88.1 approximately 89.9% at the present research centre. Also, during the eclipse, air temperature decreased slightly or remained almost unchanged. After the eclipse, however, it rose by 2.5 to 4.5 degrees C at observed stations. Meanwhile, relative humidity increased and wind speeds were lowered by the eclipse. Ground-level ozone was observed to decrease during the event.

  14. A simple method for correcting spatially resolved solar intensity oscillation observations for variations in scattered light

    Science.gov (United States)

    Jefferies, S. M.; Duvall, T. L., Jr.

    1991-01-01

    A measurement of the intensity distribution in an image of the solar disk will be corrupted by a spatial redistribution of the light that is caused by the earth's atmosphere and the observing instrument. A simple correction method is introduced here that is applicable for solar p-mode intensity observations obtained over a period of time in which there is a significant change in the scattering component of the point spread function. The method circumvents the problems incurred with an accurate determination of the spatial point spread function and its subsequent deconvolution from the observations. The method only corrects the spherical harmonic coefficients that represent the spatial frequencies present in the image and does not correct the image itself.

  15. Van Allen Probes observations of dipolarization and its associated O+ flux variations in the inner magnetosphere

    Science.gov (United States)

    Nose, M.; Keika, K.; Kletzing, C.; Smith, C. W.; MacDowall, R. J.; Reeves, G. D.; Spence, H. E.

    2015-12-01

    Recent study employing the MDS-1 satellite reveals that magnetic field dipolarization in the deep inner magnetosphere is not unusual. When the MDS-1 satellite was located at L=3.5-5.0 near the auroral onset longitude (MLT difference of ≤2.5 h), the occurrence probability of local dipolarization was about 16%. Surprisingly, an event was found at L~3.6, far inside the geosynchronous altitude. It was also shown that after the dipolarization, the oxygen ENA flux in the nightside ring current region measured by the IMAGE satellite was predominantly enhanced by a factor of 2-5 and stayed at an enhanced level for more than 1 h, while clear enhancement was scarcely seen in the hydrogen ENA flux. To better understand mechanisms of the selective acceleration of O+ ions during dipolarization, an in-situ measurement of ion fluxes is needed. However, there are few studies investigating H+ and O+ flux variations during dipolarization in the deep inner magnetosphere. In this study we investigate magnetic field dipolarization and its associated ion flux variations in the deep inner magnetosphere, using magnetic field and ion flux data obtained by the Van Allen Probes. From the magnetic field data recorded on the nightside (1800-0600 MLT) in the inner magnetosphere (L=3.0-6.6) in VDH coordinates, we select substorm-related dipolarization events in which the H component increases by more than 20 nT and the absolute value of the V component decreases by more than 8 nT in 5 minutes. About 150 dipolarization events are identified from 1 October 2012 to 30 June 2015. We find that the dipolarization mostly occurs at L=4.5-6.5 in the premidnight sector (2100-0000 MLT). No events are found at Levents are accompanied by O+ flux enhancements in the energy range higher than a few keV, which have the pitch angle distribution peaked around 45 or 135 degrees. We also find that low energy O+ ions often appear after dipolarization with an energy dispersion starting from around keV down to a few

  16. Seasonal and diurnal variation of ELF emission occurrences at 750-Hz band observed at geomagnetically conjugate stations

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Hiroyuki (Yamagata Univ. (Japan)); Sato, Natsuo (National Inst. of Polar Research, Tokyo (Japan))

    1987-06-01

    Statistical characteristics of emission occurrence are examined, using digital data of 750-Hz intensity records obtained at the conuugate pai of statins, Syowa Station in Antarrctica and Husafell in Iceland. The geographic local time at Syowa and Husafell is magnetic local time plus 3 hours and minur 1 hour, respectively. The following notable diurnal variations and seasonal variations were found: (1) The emissions were mostly observed during the daytime in the conjugate region. However, the magnetic local time when the emission occurrence rate reached maximum at Husafell was 2-3 hours later than that at Syowa. (2) The seasonal variations of emission occurrence showed the same tendency at the conjugate stations. The emission intensities showed a maximum during local summer and a minimum during local winter in both hemispheres. The ratio fo average emission intensity in each season to the intensity in winter is approximately 2.1-2.2 for summer, 1.7-1.9 for autumn, and 1.7 for spring. From these statistical characteristics, ELF emission intensity strongly depends on not only magnetic local time but also geographic local time and seasons, suggesting that ELF emissions observed on the ground are strongly controlled by the sunlight effects. The sunlight may affect the asymmetry of wave duct enhancement and wave propagation from the magnetosphere to the ionosphere in both hemisphers. Other effects are also discussed in this paper.

  17. 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.

  18. Ionosphere of venus: first observations of day-night variations of the ion composition.

    Science.gov (United States)

    Taylor, H A; Brinton, H C; Bauer, S J; Hartle, R E; Cloutier, P A; Daniell, R E; Donahue, T M

    1979-07-06

    The Bennett radio-frequency ion mass spectrometer on the Pioneer Venus orbiter is returning the first direct composition evidence of the processes responsible for the formation and maintenance of the nightside ionosphere. Early results from predusk through the nightside in the solar zenith angle range 63 degrees (dusk) to 120 degrees (dawn) reveal that, as on the dayside, the lower nightside ionosphere consists of F(1)and F(2) layers dominated by O(2)(+) and O(+), respectively. Also like the dayside, the nightside composition includes distributions of NO(+), C(+), N(+), H(+), He(+), CO(2)(+), and 28(+) (a combination of CO(+) and N(2)(+)). The surprising abundance of the nightside ionosphere appears to be maintained by the transport of O(+) from the dayside, leading also to the formation of O(2)(+) through charge exchange with CO(2). Above the exobase, the upper nightside ionosphere exhibits dramatic variability in apparent response to variations in the solar wind and interplanetary magnetic field, with the ionopause extending to several thousand kilometers on one orbit, followed by the complete rertnoval of thermal ions to altitudes below 200 kilometers on the succeeding orbit, 24 hours later. In the upper ionosphere, considerable structure is evident in many of the nightside ion profiles. Also evident are horizontal ion drifts with velocities up to the order of 1 kilometer per second. Whereas the duskside ionopause is dominated by O(+) H(+) dominates the topside on the dawnside of the antisolar point, indicating two separate regions for ion depletion in the magnetic tail regions.

  19. Informant Discrepancies in Adult Social Anxiety Disorder Assessments: Links With Contextual Variations in Observed Behavior

    Science.gov (United States)

    De Los Reyes, Andres; Bunnell, Brian E.; Beidel, Deborah C.

    2017-01-01

    Multi-informant assessments of adult psychopathology often result in discrepancies among informants’ reports. Among 157 adults meeting criteria for either the generalized (n = 106) or nongeneralized (n = 51) social anxiety disorder (SAD) subtype, we examined whether discrepancies between patients’ and clinicians’ reports of patients’ symptoms related to variations in both SAD subtype and expressions of social skills deficits across multiple social interaction tasks. Latent class analyses revealed two behavioral patterns: (a) context-specific social skills deficits and (b) cross-context social skills deficits. Similarly, patients’ symptom reports could be characterized by concordance or discordance with clinicians’ reports. Patient–clinician concordance on relatively high levels of patients’ symptoms related to an increased likelihood of the patient meeting criteria for the generalized relative to nongeneralized subtype. Further, patient–clinician concordance on relatively high levels of patients’ symptoms related to an increased likelihood of consistently exhibiting social skills deficits across social interaction tasks (relative to context-specific social skills deficits). These relations were robust in accounting for patient age, clinical severity, and Axis I and II comorbidity. Further, clinical severity did not completely explain variability in patients’ behavior on laboratory tasks or discrepancies between patient and clinician reports. Findings provide the first laboratory-based support for the ability of informant discrepancies to indicate cross-contextual variability in clinical adult assessments, and the first of any developmental period to indicate this for SAD assessments. These findings have important implications for clinical assessment and developmental psychopathology research. PMID:23421526

  20. 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.

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

    NARCIS (Netherlands)

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

    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

  2. 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 ...

  3. Preschool Children's Observed Disruptive Behavior: Variations across Sex, Interactional Context, and Disruptive Psychopathology

    Science.gov (United States)

    Gray, Sarah A. O.; Carter, Alice S.; Briggs-Gowan, Margaret J.; Hill, Carri; Danis, Barbara; Keenan, Kate; Wakschlag, Lauren S.

    2012-01-01

    Sex differences in disruptive behavior and sensitivity to social context are documented, but the intersection between them is rarely examined empirically. This report focuses on sex differences in observed disruptive behavior across interactional contexts and diagnostic status. Preschoolers (n = 327) were classified as nondisruptive (51%),…

  4. 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.

  5. Carma Observations of L1157: Chemical Complexity in the Shocked Outflow

    Science.gov (United States)

    Burkhardt, Andrew M.; Dollhopf, Niklaus M.; Corby, Joanna F.; Carroll, Brandon; Shingledecker, Christopher N.; Loomis, Ryan; Booth, S. Tom; Blake, Geoffrey; Remijan, Anthony; McGuire, Brett A.

    2016-06-01

    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. Prior to shock events an estimated ˜2000 and 4000 years ago, 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. Here, we present high spatial resolution (˜3'') maps of CH_3OH, HNCO, HCN, and HCO^+ in the southern portion of the outflow containing B1 and B2, as observed with CARMA. 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 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 HNCO abundance toward the the older shock, B2, suggests the importance of high-temperature O-chemistry in shocked regions.

  6. 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...

  7. Seasonal variations in Titan's stratosphere observed with Cassini/CIRS after the northern spring equinox

    Science.gov (United States)

    Vinatier, Sandrine; Bézard, Bruno; Teanby, Nicholas A.; Lebonnois, Sebastien; Achterberg, Richard; Gorius, Nicolas; Mamoutkine, Andrei; Flasar, F. Michael; CIRS Team

    2016-10-01

    Since 2004, Cassini has made more than 119 Titan flybys, observing its atmosphere with instruments including the Cassini Composite InfraRed Spectrometer (CIRS). We know from CIRS observations that the global dynamics drastically changed after the northern spring equinox that occurred in August 2009 ([1], [2], [3], [4]). The pole-to-pole middle atmosphere dynamics (above 100 km) experienced a global reversal in less than 2 years after the equinox [4], while the northern hemisphere was entering spring. This new pattern, with downwelling at the south pole, resulted in an enrichment of almost all molecules inside the southern polar vortex since 2011.We will present an analysis of CIRS limb observations up to 2016. We will show that many species (C2H2, HCN, HC3N, C6H6, C4H2, CH3CCH, C2H4) experienced their highest enrichments near the south pole near 500 km in March 2015, with abundances similar to in situ results from INMS at 1000 km [5], suggesting that the air inside the confined polar vortex (observed at latitudes higher than 80°S) was very efficiently transported downward from very high altitudes. In September 2015, an extension of the polar vortex towards lower latitudes (~65°S) was observed, while the molecular abundances decreased by a factor of 10 at 500 km. In the same region, unexpectedly cold stratospheric temperatures were observed below 300 km from May 2013 to the end of 2015, allowing us to detect for the first time the C6H6 ice signature at 680 cm-1. Simultaneously, after the disruption of the north polar vortex after the equinox, the enriched air that was previously confined at very high latitude gradually expended towards mid latitudes at altitudes higher than 300 km. At the beginning of 2016, a zone depleted in molecular gas and aerosol is observed in the entire northern hemisphere between 400 and 500 km, suggesting some complex unknown dynamical effect.References:[1] Teanby, N. et al., 2012, Nature, 491, pp. 733-735.[2] Achterberg et al., DPS 46

  8. Seasonal variations of infrasonic arrivals from long term ground truth observations in Nevada and implication for event location

    Science.gov (United States)

    Negraru, Petru; Golden, Paul

    2017-01-01

    SUMMARYLong term ground truth observations were collected at two infrasound arrays in Nevada to investigate how seasonal atmospheric variations affect the detection, travel time and signal characteristics (azimuth, trace velocity, frequency content and amplitudes) of infrasonic arrivals at regional distances. The arrays were located in different azimuthal directions from a munition disposal facility in Nevada. FNIAR, located 154 km north of the source has a high detection rate throughout the year. Over 90% of the detonations have travel times indicative of stratospheric arrivals, while tropospheric waveguides are observed from only 27% of the detonations. The second array, DNIAR, located 293 km southeast of the source exhibits strong seasonal variations with high stratospheric detection rates in winter and the virtual absence of stratospheric arrivals in summer. Tropospheric waveguides and thermospheric arrivals are also observed for DNIAR. Modelling through the Naval Research Laboratory Ground to Space (G2S) atmospheric sound speeds leads to mixed results: FNIAR arrivals are usually not predicted to be present at all (either stratospheric or tropospheric), while DNIAR arrivals are usually correctly predicted, but summer arrivals show a consistent travel time bias. In the end we show the possible improvement in location using empirically calibrated travel time and azimuth observations. Using the Bayesian Infrasound Source Localization we show that we can decrease the area enclosed by the 90% credibility contours by a factor of 2.5.

  9. The fine-structure constant a new observational limit on its cosmological variation and some theoretical consequences

    CERN Document Server

    Ivanchik, A V; Varshalovich, D A

    1999-01-01

    Endeavours of the unification of the four fundamental interactions have resulted in a development of theories having cosmological solutions in which low-energy limits of fundamental physical constants vary with time. The validity of such theoretical models should be checked by comparison of the theoretical predictions with observational and experimental bounds on possible time-dependences of the fundamental constants. Based on high-resolution measurements of quasar spectra, we obtain the following direct limits on the average rate of the cosmological time variation of the fine-structure constant limit, and |\\dot{\\alpha}/\\alpha| < 3.1 \\times 10^{-14} yr^{-1} is the most conservative limit. Analogous estimates published previously, as well as other contemporary tests for possible variations of \\alpha (those based on the "Oklo phenomenon", on the primordial nucleosynthesis models, and others) are discussed and compared with the present upper limit. We argue that the present result is the most conservative one...

  10. 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.)

  11. 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

  12. 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.

  13. Herschel Extreme Lensing Line Observations: [CII] Variations in Galaxies at Redshifts z=1–3

    Science.gov (United States)

    Malhotra, Sangeeta; Rhoads, James E.; Finkelstein, K.; Yang, Huan; Carilli, Chris; Combes, Françoise; Dassas, Karine; Finkelstein, Steven; Frye, Brenda; Gerin, Maryvonne; Guillard, Pierre; Nesvadba, Nicole; Rigby, Jane; Shin, Min-Su; Spaans, Marco; Strauss, Michael A.; Papovich, Casey

    2017-01-01

    We observed the [C ii] line in 15 lensed galaxies at redshifts 1 HELLO sample is similar to the values seen for low-redshift galaxies, indicating that small grains and PAHs dominate the heating in the neutral ISM, although some of the high [CII]/FIR ratios may be due to turbulent heating. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  14. Velocity variation of internal shock waves in gamma ray bursts: Observational properties

    Institute of Scientific and Technical Information of China (English)

    WU; Mei; CHEN; Li; QU; Jinlu; Poon; Helen; WU; Bobing; SONG; Liming

    2006-01-01

    The work uses the data in the TTS mode of BATSE to analyze the time lags and pulse widths of GRB960113 and GRB960722 in high as well as low energy bands. The results show that their time lags increase monotonously. This phenomenon can reasonably be interpreted with the model of internal shock waves of γ-ray bursts (GRB). Perhaps we obtain the direct observational evidence for the fireball model of GRBs for the first time.

  15. Inter-annual variations of CO2 observed by commercial airliner in the CONTRAIL project

    Science.gov (United States)

    Sawa, Yousuke; Machida, Toshinobu; Matsueda, Hidekazu; Niwa, Yosuke; Umezawa, Taku

    2016-04-01

    Since 2005, we have conducted an observation program for greenhouse gases using the passenger aircraft of the Japan Airlines named Comprehensive Observation Network for TRace gases by AIrLiner (CONTRAIL). Over the past 10 years, successful operation of Continuous CO2 Measuring Equipment (CME) has delivered more than 6 million in-situ CO2 data from about 12000 flights between Japan and Europe, Australia, North America, or Asia. The large number of CME data enable us to well characterize spatial distributions and seasonal changes of CO2 in wide regions of the globe especially the Asia-Pacific regions. While the mean growth rates for the past 10 years were about 2 ppm/year, large growth rates of about 3 ppm/year were found in the wide latitudinal bands from 30S to 70N from the second half of 2012 to the first half of 2013. The multiyear data sets have the potential to help understand the global/regional CO2 budget. One good example is the significant inter-annual difference in CO2 vertical profiles observed over Singapore between October 2014 and October 2015, which is attributable to the massive biomass burnings in Indonesia in 2015.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Hopstaken, R.M. E-mail: rogier.hopstaken@hag.unimaas.nl; Witbraad, T.; Engelshoven, J.M.A. van; Dinant, G.J

    2004-08-01

    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 ({kappa}=0.20) or Streptococcus pneumoniae ({kappa}=-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.

  2. Airborne observations of regional variation in fluorescent aerosol across the United States

    OpenAIRE

    2015-01-01

    Airborne observations of fluorescent aerosol were made aboard an airship during CloudLab, a series of flights that took place in September and October of 2013 and covered a wideband of longitude across the continental U.S. between Florida and California and between 28 and 37-N latitudes. Sampling occurred from near the surface to 1000-m above the ground. A Wideband Integrated Bioaerosol Sensor (WIBS-4) measured average concentrations of supermicron fluorescent particles aloft (1-μm to 10-μm),...

  3. Hybrid variational-ensemble assimilation of lightning observations in a mesoscale model

    Directory of Open Access Journals (Sweden)

    K. Apodaca

    2014-05-01

    Full Text Available Lightning measurements from the Geostationary Lightning Mapper (GLM that will be aboard the Goestationary Operational Environmental Satellite – R Series will bring new information that can have the potential for improving the initialization of numerical weather prediction models by assisting in the detection of clouds and convection through data assimilation. In this study we focus on investigating the utility of lightning observations in mesoscale and regional applications suitable for current operational environments, in which convection cannot be explicitly resolved. Therefore, we examine the impact of lightning observations on storm environment. Preliminary steps in developing a lightning data assimilation capability suitable for mesoscale modeling are presented in this paper. World Wide Lightning Location Network (WWLLN data was utilized as a proxy for GLM measurements and was assimilated with the Maximum Likelihood Ensemble Filter, interfaced with the Nonhydrostatic Mesoscale Model core of the Weather Research and Forecasting system (WRF-NMM. In order to test this methodology, regional data assimilation experiments were conducted. Results indicate that lightning data assimilation had a positive impact on the following: information content, influencing several dynamical variables in the model (e.g., moisture, temperature, and winds, improving initial conditions, and partially improving WRF-NMM forecasts during several data assimilation cycles.

  4. Equatorial Spread F structures and associated airglow intensity variations observed over Gadanki

    Directory of Open Access Journals (Sweden)

    R. Sekar

    2008-12-01

    Full Text Available Co-ordinated campaigns have been conducted from Gadanki (13.5° N, 79.2° E, dip lat 6.4° N by operating simultaneously the Indian MST radar in ionospheric coherent backscatter mode and by monitoring thermosphere airglow line emissions (630.0 nm and 777.4 nm using a narrow band multi-wavelength scanning photometer during January-March for the past five years (2003–2007 and also during April 2006, as a special campaign. Simultaneous radar and optical observations reveal optical signatures corresponding to a variety of equatorial spread F (ESF structures. The optical signatures corresponding to ESF structures with wave-like bottomside modulations with plasma plumes, confined bottomside flat and wavelike structures, vertically extended plume structure in the absence of bottomside structure apart from the classical plasma depletions and enhancements are obtained during these campaigns. The plasma depletions and enhancements were identified using optical measurements. In addition, estimations of zonal wavelength of the bottomside structures and the inference of shears in the zonal plasma drift in the presence of confined structures, were carried out using bi-directional airglow measurements. Furthermore, it is found that the vertical columnar intensity of OI 630.0 nm airglow exceeded the slanted columnar intensity in the presence of large bottomside structure. The need for the appropriate physical mechanisms for some of the ESF structures and their characterizations with optical observations are discussed.

  5. Cassini UVIS observations of the Io plasma torus. II. Radial variations

    CERN Document Server

    Steffl, Andrew J; Stewart, A Ian F; 10.1016/j.icarus.2004.04.016

    2013-01-01

    On January 14, 2001, shortly after the Cassini spacecraft's closest approach to Jupiter, the Ultraviolet Imaging Spectrometer (UVIS) made a radial scan through the midnight sector of Io plasma torus. The Io torus has not been previously observed at this local time. The UVIS data consist of 2-D spectrally dispersed images of the Io plasma torus in the wavelength range of 561{\\AA}-1912{\\AA}. We developed a spectral emissions model that incorporates the latest atomic physics data contained in the CHIANTI database in order to derive the composition of the torus plasma as a function of radial distance. Electron temperatures derived from the UVIS torus spectra are generally less than those observed during the Voyager era. We find the torus ion composition derived from the UVIS spectra to be significantly different from the composition during the Voyager era. Notably, the torus contains substantially less oxygen, with a total oxygen-to-sulfur ion ratio of 0.9. The average ion charge state has increased to 1.7. We de...

  6. 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...

  7. Spatial and Temporal Variation in Fine Particulate Matter Mass and Chemical Composition: The Middle East Consortium for Aerosol Research Study

    Directory of Open Access Journals (Sweden)

    Ziad Abdeen

    2014-01-01

    Full Text Available Ambient fine particulate matter (PM2.5 samples were collected from January to December 2007 to investigate the sources and chemical speciation in Palestine, Jordan, and Israel. The 24-h PM2.5 samples were collected on 6-day intervals at eleven urban and rural sites simultaneously. Major chemical components including metals, ions, and organic and elemental carbon were analyzed. The mass concentrations of PM2.5 across the 11 sites varied from 20.6 to 40.3 μg/m3, with an average of 28.7 μg/m3. Seasonal variation of PM2.5 concentrations was substantial, with higher average concentrations (37.3 μg/m3 in the summer (April–June months compared to winter (October–December months (26.0 μg/m3 due mainly to high contributions of sulfate and crustal components. PM2.5 concentrations in the spring were greatly impacted by regional dust storms. Carbonaceous mass was the most abundant component, contributing 40% to the total PM2.5 mass averaged across the eleven sites. Crustal components averaged 19.1% of the PM2.5 mass and sulfate, ammonium, and nitrate accounted for 16.2%, 6.4%, and 3.7%, respectively, of the total PM2.5 mass. The results of this study demonstrate the need to better protect the health and welfare of the residents on both sides of the Jordan River in the Middle East.

  8. Calving and velocity variations observed by Terrestrial Radar Interferometry at Jakobshavn Isbræ, Greenland, in 2015

    Science.gov (United States)

    Xie, S.; Voytenko, D.; Holland, D.; Dixon, T. H.

    2015-12-01

    We observed the highly dynamic terminus of Jakobshavn Isbræ in Greenland by using a Terrestrial Radar Interferometer (TRI) during a 5 days' period in early June, 2015. Calving and ice surface velocity variations were captured by our continuous measurements with a sampling rate of 90 seconds. Our terrestrial-derived time series show that calving events are characterized by suddenly fluctuations in surface velocities, which is very distinct in the mélange and less distinct on the glacier. Except for the relatively fast and steady motion, the glacier also moves in response to the semidiurnal ocean tides, and the impact of tides decreases rapidly upstream from the terminus.

  9. 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

  10. Observation of muon intensity variations by season with the MINOS Near Detector

    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; Fields, T H; 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; Mathis, M; 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

    2014-01-01

    A sample of 1.53$\\times$10$^{9}$ cosmic-ray-induced single muon events has been recorded at 225 meters-water-equivalent using the MINOS Near Detector. The underground muon rate is observed to be highly correlated with the effective atmospheric temperature. The coefficient $\\alpha_{T}$, relating the change in the muon rate to the change in the vertical effective temperature, is determined to be 0.428$\\pm$0.003(stat.)$\\pm$0.059(syst.). An alternative description is provided by the weighted effective temperature, introduced to account for the differences in the temperature profile and muon flux as a function of zenith angle. Using the latter estimation of temperature, the coefficient is determined to be 0.352$\\pm$0.003(stat.)$\\pm$0.046(syst.).

  11. 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...

  12. Observation of muon intensity variations by season with the MINOS Near Detector

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, P.; et al.

    2014-07-22

    A sample of 1.53$\\times$10$^{9}$ cosmic-ray-induced single muon events has been recorded at 225 meters-water-equivalent using the MINOS Near Detector. The underground muon rate is observed to be highly correlated with the effective atmospheric temperature. The coefficient $\\alpha_{T}$, relating the change in the muon rate to the change in the vertical effective temperature, is determined to be 0.428$\\pm$0.003(stat.)$\\pm$0.059(syst.). An alternative description is provided by the weighted effective temperature, introduced to account for the differences in the temperature profile and muon flux as a function of zenith angle. Using the latter estimation of temperature, the coefficient is determined to be 0.352$\\pm$0.003(stat.)$\\pm$0.046(syst.).

  13. Seasonal Variations of Mid-Latitude Ionospheric Trough Structure Observed with DEMETER and COSMIC

    Directory of Open Access Journals (Sweden)

    Matyjasiak Barbara

    2016-12-01

    Full Text Available The mid-latitude ionospheric trough is a depleted region of ionospheric plasma observed in the topside ionosphere. Its behavior can provide useful information about the magnetospheric dynamics, since its existence is sensitive to magnetospherically induced motions. Mid-latitude trough is mainly a night-time phenomenon. Both, its general features and detailed characteristics strongly depend on the level of geomagnetic disturbances, time of the day, season, and the solar cycle, among others. Although many studies provide basic information about general characteristics of the main ionospheric trough structure, an accurate prediction of the trough behavior in specific events is still understood poorly. The paper presents the mid-latitude trough characteristics with regard to the geomagnetic longitude and season during a solar activity minimum, as based on the DEMETER in situ satellite measurements and the data retrieved from FORMOSAT-3/COSMIC radio occultation measurements.

  14. 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.

  15. 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.

  16. Observation of muon intensity variations by season with the MINOS near detector

    Energy Technology Data Exchange (ETDEWEB)

    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.; Devan, A. V.; Devenish, N. E.; Diwan, M. V.; Escobar, C. O.; Evans, J. J.; Falk, E.; Feldman, G. J.; Fields, T. H.; 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.; Mathis, M.; Mayer, N.; McGivern, C.; Medeiros, M. M.; Mehdiyev, R.; Meier, J. R.; Messier, M. D.; Miller, W. H.; Mishra, S. R.; Moed Sher, S.; Moore, C. D.; Mualem, L.; Musser, J.; Naples, D.; Nelson, J. K.; Newman, H. B.; Nichol, R. J.; Nowak, J. A.; O’Connor, J.; 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.

    2014-07-01

    A sample of 1.53$\\times$10$^{9}$ cosmic-ray-induced single muon events has been recorded at 225 meters-water-equivalent using the MINOS Near Detector. The underground muon rate is observed to be highly correlated with the effective atmospheric temperature. The coefficient $\\alpha_{T}$, relating the change in the muon rate to the change in the vertical effective temperature, is determined to be 0.428$\\pm$0.003(stat.)$\\pm$0.059(syst.). An alternative description is provided by the weighted effective temperature, introduced to account for the differences in the temperature profile and muon flux as a function of zenith angle. Using the latter estimation of temperature, the coefficient is determined to be 0.352$\\pm$0.003(stat.)$\\pm$0.046(syst.).

  17. Investigating the presence of post-perovskite and large-scale chemical variations in Earth's lower mantle using tomographic-geodynamic model comparisons.

    Science.gov (United States)

    Koelemeijer, Paula; Ritsema, Jeroen; Deuss, Arwen; Davies, Rhodri; Schuberth, Bernhard

    2016-04-01

    Tomographic models of the Earth's mantle consistently image two large provinces of low shear-wave velocities (LLSVPs) in the lowermost mantle beneath Africa and the Pacific. Seismic studies also find an increase in the ratio of shear-wave velocity (Vs) to compressional-wave velocity (Vp) variations, accompanied by a significant negative correlation between shear-wave and bulk-sound velocity (Vc) variations, both of which are also observed in the recent SP12RTS model. The LLSVPs have consequently been suggested to represent intrinsically dense piles of thermochemical material. Alternatively, they have been interpreted as poorly imaged clusters of thermal plumes, with the deep mantle post-perovskite (pPv) phase invoked as explanation for the high Vs/Vp ratios and Vs-Vc anti-correlation. Geodynamical calculations of thermal plumes and thermochemical piles predict a fundamentally different style of mantle convection, interface topographies and CMB heat flow. However, to interpret tomographic images using these high-resolution models, the limited resolving power of seismic tomography has to be accounted for. Here, we interpret the observed seismic characteristics of SP12RTS by comparing the velocity structures to synthetic tomography images derived from 3D mantle convection models. As in previous studies, geodynamic models are converted to seismic velocities using mineral physics constraints and subsequently convolved with the tomographic resolution operator. In contrast to these studies, where generally only the shear-wave velocity structure has been compared, we use both the Vs and Vp resolution operator of SP12RTS to allow direct comparisons of the resulting velocity ratios and correlations. We use geodynamic models with and without pPv and/or chemical variations to investigate the cause of the high Vs/Vp ratio and Vs-Vs anti-correlation. Although the tomographic filtering significantly affects the synthetic tomography images, we demonstrate that the patterns

  18. Short-term temporal variation in sporulation dynamics of arbuscular mycorrhizal (AM) fungi and physico-chemical edaphic properties of wheat rhizosphere.

    Science.gov (United States)

    Panwar, Vipin; Meghvansi, M K; Siddiqui, Sazada

    2011-07-01

    In this study, we investigated the pattern of short-term temporal variation in the arbuscular mycorrhizal (AM) fungi and physico-chemical edaphic properties of some wheat growing areas of the Bundelkhand region, Central India. Rhizospheric soil samples were collected every month from December 2007 to May 2008 from four wheat growing sites around Jhansi (Bundelkhand region). AM fungal root colonization, sporulation and physico-chemical edaphic properties during this period were determined and compared to evaluate the dynamics of response of wheat towards the AMF along crop maturation. Maximum AMF root colonization recorded was 54.3% indicating that AMF, particularly in low phosphorus (P) soils, can be important even in case of less responsive crop like wheat. In the two out of four sites studied, the AMF spore density increased with the increase in soil temperature. Absence of this type of pattern in remaining two sites indicated that site-specific environmental and agricultural conditions may affect the degree of wheat response to AMF. It also suggested that AMF communities inhabiting agroecosystems may exhibit considerable temporal sporulation patterns. The maximum AMF colonization was observed during February-March 2008, whereas maximum AMF sporulation was noticed during March-April 2008. Statistically significant negative correlation of AMF spore density with pH, organic carbon (OC) and available P was observed in the one of the sites studied. Overall assessment of the data indicated that season and location significantly affected the interaction of AM fungi with winter wheat necessitating the further need to understand the ecology of AMF populations with reference to specific host species under different micro-climatic conditions of Bundelkhand region.

  19. A three-dimensional variational data assimilation system for the South China Sea: preliminary results from observing system simulation experiments

    Science.gov (United States)

    Peng, Shiqiu; Zeng, Xuezhi; Li, Zhijin

    2016-05-01

    A three-dimensional variational data assimilation (3DVAR) system based on the Regional Ocean Modeling System (ROMS) is established for the South China Sea (SCS). A set of Observing System Simulation Experiments (OSSEs) are performed to evaluate the performance of this data assimilation system and investigate the impacts of different types of observations on representation of three-dimensional large-scale circulations and meso-scale eddies in the SCS. The pseudo-observations that are examined include sea surface temperatures (SSTs), sea surface heights (SSHs), sparse temperature/salinity (T/S) profiles, sea surface velocities (SSVs), and sea surface salinities (SSSs). The results show that SSHs can extend their impacts into the subsurface or even the deep ocean while other surface observations only have impacts within surface mixed layer. SSVs have similar impacts though confined to their spatial coverage, suggesting that SSVs could be a substitute of SSHs nearshore where SSHs are of poor quality. Despite their sparseness, the T/S profiles improve the representation of the temperature and salinity structures below the mixed layer, and a combination of T/S profiles with surface observations leads to a better representation of the meso-scale eddies. Based on the OSSE results, an affordable observing network for the SCS in the near future is proposed.

  20. Chemical and Physical Properties of Bulk Aerosols within Four Sectors Observed during TRACE-P

    Science.gov (United States)

    Jordan, C. E.; Anderson, B. E.; Talbot, R. W.; Dibb, J. E.; Fuelberg, E.; Hudgins, C. H.; Kiley, C. M.; Russo, R.; Scheuer, E.; Seid, G.

    2003-01-01

    Chemical and physical aerosol data collected on the DC-8 during TRACE-P were grouped into four sectors based on back trajectories. The four sectors represent long-range transport from the west (WSW), regional circulation over the western Pacific and Southeast Asia (SE Asia), polluted transport from Northern Asia with substantial sea salt at low altitudes (NNW) and a substantial amount of dust (Channel). WSW has generally low mixing ratios at both middle and high altitudes, with the bulk of the aerosol mass due to non-sea-salt water-soluble inorganic species. Low altitude SE Asia also has low mean mixing ratios in general, with the majority of the aerosol mass comprised of non-sea-salts, however, soot is also relatively important m this region. "w had the highest mean sea salt mixing ratios, with the aerosol mass at low altitudes (a km) evenly divided between sea salts, mm-sea-salts, and dust. The highest mean mixing ratios of water-soluble ions and soot were observed at the lowest altitudes (a km) in the Channel sector. The bulk of the aerosol mass exported from Asia emanates h m Channel at both low and midaltitudes, due to the prevalence of dust compared to other sectors. Number densities show enhanced fine particles for Channel and NNW, while their volume distributions are enhanced due to sea salt and dust Low-altitude Channel exhibits the highest condensation nuclei ((34) number densities along with enhanced scattering coefficients, compared to the other sectors. At midaltitudes (2-7 km), low mean CN number densities coupled with a high proportion of nonvolatile particles (265%) observed in polluted sectors (Channel and NNW) are attributed to wet scavenging which removes hygroscopic CN particles. Low single scatter albedo m SE Asia reflects enhanced soot

  1. 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.

  2. 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

  3. 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.

  4. Recent observations on the physico-chemical speciation of plutonium in the Irish Sea and the western Mediterranean

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, P.I.; Downes, A.B.; Condren, O.M.; Vintro, L.L. [University Coll., Dublin (Ireland). Dept. of Experimental Physics; Batlle, J.V.I. [Pittsburgh Univ., PA (United States). Centre for Environmental and Occupational Health and Toxicology; Sanchez-Cabeza, J.A. [Universidad Autonoma de Barcelona (Spain). Dept. de Fisica

    1995-11-01

    Data on the physico-chemical speciation of Pu in the Irish Sea and the western Mediterranean, gathered in the course of research expeditions carried out in the period 1988-93, are reviewed in detail in this paper. Measurements of the oxidation state distribution of {sup 239,240}Pu (and {sup 238}Pu) in filtered water sampled throughout the Irish Sea show little variation, geographically or temporally, with some 87 {+-} 6% in the oxidized, Pu(V), state overall. No distinction is observed between surface and bottom waters, reflecting both the shallow and the well-mixed nature of these waters. Interestingly, the {sup 241}Pu(IV)/{sup 239,240}Pu(IV) ratio in filtered water from the north-eastern Irish Sea, close to the Sellafield source-term, is found to be significantly higher than the corresponding {sup 241}Pu(V)/{sup 239,240}Pu(V) ratio, while the latter appears to be identical to the {sup 241}Pu/{sup 239,240}Pu ratio in suspended particulate from the same zone. It is suggested that this distinction is of importance in the interpretation of the mechanisms responsible for the hold-up and dispersion of Pu in the near field. The percentage of Pu in colloidal form in open waters, as operationally defined by enhanced sorption on Al{sub 2}O{sub 3}, seldom exceeds 15%. There is some evidence of higher percentages in near-shore waters containing proportionately more Pu in the reduced, Pu(IV), state. (author).

  5. 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, ...

  6. Observational manifestations of solar magneto-convection -- center-to-limb variation

    CERN Document Server

    Carlsson, M; Nordlund, A; Scharmer, G; Carlsson, Mats; Stein, Robert F.; Nordlund, Ake; Scharmer, Goran

    2004-01-01

    We present the first center-to-limb G-band images synthesized from high resolution simulations of solar magneto-convection. Towards the limb the simulations show "hilly" granulation with dark bands on the far side, bright granulation walls and striated faculae, similar to observations. At disk center G-band bright points are flanked by dark lanes. The increased brightness in magnetic elements is due to their lower density compared with the surrounding intergranular medium. One thus sees deeper layers where the temperature is higher. At a given geometric height, the magnetic elements are cooler than the surrounding medium. In the G-band, the contrast is further increased by the destruction of CH in the low density magnetic elements. The optical depth unity surface is very corrugated. Bright granules have their continuum optical depth unity 80 km above the mean surface, the magnetic elements 200-300 km below. The horizontal temperature gradient is especially large next to flux concentrations. When viewed at an ...

  7. Martian Cryogenic Carbonate Formation: Stable Isotope Variations Observed in Laboratory Studies

    Science.gov (United States)

    Socki, Richard A.; Niles, Paul B.; Sun, Tao; Fu, Qi; Romanek, Christopher S.; Gibson, Everett K. Jr.

    2014-01-01

    The history of water on Mars is tied to the formation of carbonates through atmospheric CO2 and its control of the climate history of the planet. Carbonate mineral formation under modern martian atmospheric conditions could be a critical factor in controlling the martian climate in a means similar to the rock weathering cycle on Earth. The combination of evidence for liquid water on the martian surface and cold surface conditions suggest fluid freezing could be very common on the surface of Mars. Cryogenic calcite forms easily from freezing solutions when carbon dioxide degasses quickly from Ca-bicarbonate-rich water, a process that has been observed in some terrestrial settings such as arctic permafrost cave deposits, lake beds of the Dry Valleys of Antarctica, and in aufeis (river icings) from rivers of N.E. Alaska. A series of laboratory experiments were conducted that simulated cryogenic carbonate formation on Mars in order to understand their isotopic systematics. The results indicate that carbonates grown under martian conditions show variable enrichments from starting bicarbonate fluids in both carbon and oxygen isotopes beyond equilibrium values.

  8. 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.

  9. Chemical variability and biological activities of Brassica rapa var. rapifera parts essential oils depending on geographic variation and extraction technique.

    Science.gov (United States)

    Saka, Boualem; Djouahri, Abderrahmane; Djerrad, Zineb; Souhila, Terfi; Aberrane, Sihem; Sabaou, Nasserdine; Baaliouamer, Aoumeur; Boudarene, Lynda

    2017-02-01

    In the present work, the Brassica rapa var. rapifera parts essential oils and their antioxidant and antimicrobial activities were investigated for the first time depending on geographic origin and extraction technique. GC and GC-MS analyses showed several constituents, including alcohols, aldehydes, esters, ketones, norisoprenoids, terpenic, nitrogen and sulphur compounds, totalizing 38 and 41 compounds in leaves and root essential oils, respectively. Nitrogen compounds were the main volatiles in leaves essential oils and sulphur compounds were the main volatiles in root essential oils. Qualitative and quantitative differences were found among B. rapa var. rapifera parts essential oils collected from different locations and extracted by hydrodistillation (HD) and microwave-assisted hydrodistillation (MAHD) techniques. Furthermore, our findings showed a high variability for both antioxidant and antimicrobial activities. The highlighted variability reflects the high impact of plant part, geographic variation and extraction technique on chemical composition and biological activities, which led to conclude that we should select essential oils to be investigated carefully depending on these factors, in order to isolate the bioactive components or to have the best quality of essential oil in terms of biological activities and preventive effects in food. This article is protected by copyright. All rights reserved.

  10. Comparison of Variations in the Chemical Constituents of the Rhizome and Culm of Phyllostachys pubescens at Different Ages

    Directory of Open Access Journals (Sweden)

    Bin Xu

    2014-09-01

    Full Text Available A systematic study was conducted on Phyllostachys pubescens by analyzing the chemical constituents of its rhizome and culm at different ages. Our results indicated that the ash contents of the rhizome and culm of P. pubescens at different ages showed the largest coefficient of variation (CV, followed by alcohol benzene extractives. The CVs of acid-insoluble lignin, holocellulose, HNO3-C2H5OH cellulose, and pentosan were relatively small. Analysis of t-tests indicated that significant differences were found in the contents of extractives, acid-insoluble lignin, holocellulose, and ash of rhizome and culm (p < 0.05. The differences in contents of HNO3-C2H5OH cellulose and pentosan were not significant. Analysis of multiplicity showed that the contents of HNO3-C2H5OH cellulose, pentosan, and ash were not significantly different in bamboos at the ages examined. Likewise, the contents of lignin, alcohol benzene extractives, and holocellulose exhibited no significant difference between one-year-old and three-year-old bamboos. However, the differences in these parameters between five-year-old bamboos and one- and three-year-old bamboos were all statistically significant. Our results suggest that three-year-old P. pubescens is suitable for use as a raw material for papermaking. In addition, our findings provide a theoretical basis for effective utilization of P. pubescens and enhancement of its value.

  11. Understanding field variation, quantum chemical modeling and molecular orbital analyses of trans-3-(trans-4-imidazolyl) acrylic acid

    Science.gov (United States)

    Gayathri, R.; Arivazhagan, M.

    2017-02-01

    In this work, a joint experimental (FTIR and FT-Raman) and theoretical (DFT and ab-initio) study on the structure and the vibrations of Trans-3-(trans-4-imidazolyl) acrylic acid (TTIAA) are compared and analyzed. The assignment of each normal mode has been made using the observed and calculated frequencies. The optimized geometries, harmonic vibrational wavenumbers and intensities of vibrational bands of trans-3-(trans-4-imidazolyl) acrylic acid (TTIAA) have been carried out using the HF/B3LYP method using the standard 6311++G(d,p) basis set calculations in this investigation. The result describes the variation in electrostatic and transport properties for zero and various external applied field. The variation in MPA charges are small due to the application of EFs: however, in most cases it is found to be systematic and almost uniform. When the field increases from 0.00 to 0.02 VÅ-1, the hybridization of molecular levels broadens the DOS and decreases the HLG from 3.6609 to 1.2325 eV; the decrease of band gap at the high field indicates that this molecule exhibit considerable electrical conductivity. Fukui indices to determine the local reactive site for the molecular systems during electrophilic, nucleophilic, radical and dual descriptor attacks. The results clearly show the superiority of MPA scheme. This study may be useful to design new molecules with more electrical conductivity.

  12. Intradiurnal wind variations observed in the lower thermosphere over the South Pole

    Directory of Open Access Journals (Sweden)

    Y. I. Portnyagin

    Full Text Available The first meteor radar measurements of meridional winds in the lower thermosphere (about 95 ± 5 km, along four azimuth directions: 0°, 90°E, 180° and 90°W; approximately 2° from the geographic South Pole were made during two observational campaigns: January 19, 1995-January 26, 1996, and November 21, 1996-January 27, 1997. Herein we report analyses of the measurement results, obtained during the first campaign, which cover the whole one-year period, with particular emphasis on the transient nature and seasonal behavior of the main parameters of the intradiurnal wind oscillations. To analyze the data, two complementary methods are used: the well-known periodogram (FFT technique and the S-transform technique. The most characteristic periods of the intradiurnal oscillations are found to be rather uniformly spread between about 7 h and 12 h. All of these oscillations are westward-propagating with zonal wave number s=1 and their usual duration is confined to several periods. During the austral winter season the oscillations with periods less than 12 h are the most intensive, while during summer season the 12-h oscillations dominate. Lamb waves and internal-gravity wave propagation, non-linear interaction of the short-period tides, excitation in situ of the short period waves may be considered as possible processes which are responsible for intradiurnal wind oscillations in the lower thermosphere over South Pole.

    Key words: Meteorology and atmospheric dynamics (middle atmosphere dynamics; thermospheric dynamics; waves and tides

  13. A study of variation characteristics of Gobi broadband emissivity based on field observational experiments in northwestern China

    Science.gov (United States)

    Zheng, Zhi-yuan; Wei, Zhi-gang; Wen, Zhi-ping; Dong, Wen-jie; Li, Zhen-chao; Wen, Xiao-hang; Zhu, Xian; Chen, Chen; Hu, Shan-shan

    2017-02-01

    Land surface emissivity is a significant variable in energy budgets, land cover assessments, and environment and climate studies. However, the assumption of an emissivity constant is being used in Gobi broadband emissivity (GbBE) parameterization scheme in numerical models because of limited knowledge surrounding the spatiotemporal variation characteristics of GbBE. To address this issue, we analyzed the variation characteristics of GbBE and possible impact factor-surface soil moisture based on long-term continuous and high temporal resolution field observational experiments over a typical Gobi underlying surface in arid and semiarid areas in northwestern China. The results indicate that GbBE has obvious daily and diurnal variation features, especially diurnal cycle characteristics. The multi-year average of the daily average of GbBE is in the range of 0.932 to 0.970 with an average of 0.951 ± 0.008, and the average diurnal GbBE is in the range of 0.880 to 0.940 with an average of 0.906 ± 0.018. GbBE varies with surface soil moisture content. We observed a slight decrease in GbBE with an increase in soil moisture, although this change was not very obvious because of the low soil moisture in this area. Nevertheless, we think that soil moisture must be one of the most significant impact factors on GbBE in arid and semiarid areas. Soil moisture must be taken into account into the parameterization schemes of bare soil broadband emissivity in land surface models. Additional field experiments and studies should be carried out in order to clarify this issue.

  14. Problems of variational assimilation of observational data for ocean general circulation models and methods for their solution

    Science.gov (United States)

    Agoshkov, V. I.; Ipatova, V. M.; Zalesnyi, V. B.; Parmuzin, E. I.; Shutyaev, V. P.

    2010-12-01

    Problems of the variational assimilation of satellite observational data on the temperature and level of the ocean surface, as well as data on the temperature and salinity of the ocean from the ARGO system of buoys, are formulated with the use of the global three-dimensional model of ocean thermodynamics developed at the Institute of Numerical Mathematics, Russian Academy of Sciences (INM RAS). Algorithms for numerical solutions of the problems are developed and substantiated, and data assimilation blocks are developed and incorporated into the global three-dimensional model. Numerical experiments are performed with the use of the Indian Ocean or the entire World Ocean as examples. These numerical experiments support the theoretical conclusions and demonstrate that the use of a model with an assimilation block of operational observational data is expedient.

  15. Variations in the drift of larval cod ( Gadus morhua L.) in the Baltic Sea : combining field observations and modelling

    DEFF Research Database (Denmark)

    Voss, R.; Hinrichsen, H.H.; St. John, Michael

    1999-01-01

    Coupled three-dimensional (3-D) physical oceanographic modelling and field sampling programmes were carried out in May 1988 and August 1991 to investigate the potential drift of larval cod (Gadus morhua L.) in the Bornholm Basin of the Baltic Sea. The goals were to predict the transport of cod...... for the time periods considered. Larval drift was simulated either by incorporation of passive drifters, or as the initial horizontal distribution of larvae implemented into the model. Drift model simulations of larval transport agreed relatively well with field observations. The influence of variations...... in the vertical distribution on a smaller scale, i.e. vertical deviations of +/- 6 m from the observed mean centre of mass, on the drift was examined, revealing no significant differences in the drift of larvae depending on their vertical distribution. The different wind forcing during the investigated time...

  16. Interpretation of spatial and temporal variations of hydrogen quadrupole absorptions in the Jovian atmosphere observed during the 1972 apparition

    Science.gov (United States)

    Hunt, G. E.; Bergstralh, J. T.

    1977-01-01

    Results are reported for a systematic investigation of temporal and spatial variations of hydrogen quadrupole lines formed in the Jovian atmosphere, which was performed by measuring the strengths of the S(1) lines of H2 (3,0) and (4,0) quadrupole bands at several points on the Jovian disk during the 1972 apparition. The observations support the hypothesis that the strength of the (3,0) S(1) line varies significantly with time, suggest the possibility of short-term temporal variation in the strength of the (4,0) line, and indicate that the H2 line strengths vary remarkably little from limb to limb in the equatorial region. A Galatry line-shape profile is calculated, and a radiative-transfer analysis is carried out using the Henyey-Greenstein phase function for single particle scattering. It is shown that the observations are consistent with a multilayer atmospheric model having an optically thin upper cloud deck separated by a stratum of nonscattering gas from an optically thick lower cloud.

  17. 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

  18. Volcanological implications of crystal-chemical variations in clinopyroxenes from the Aeolian Arc, Southern Tyrrhenian Sea (Italy)

    Science.gov (United States)

    Nazzareni, Sabrina; Molin, Gianmario; Peccerillo, Angelo; Zanazzi, Pier Francesco

    2001-03-01

    Crystal chemistry and structural data for clinopyroxene from the Aeolian islands (Southern Tyrrhenian Sea, Italy) were determined with the aim of obtaining geobarometric information and exploring implications for the structure of volcanic plumbing systems. Cell and M1 site volumes for clinopyroxenes, which are known to decrease with increasing pressure of crystallization, revealed variable values, both within some single islands and along the entire arc, indicating polybaric conditions of crystallization. The lowest cell and M1 volumes were found at Filicudi, plotting close to values of clinopyroxenes from high-pressure ultramafic xenoliths entrained in alkali basalts. Indications of high-pressure crystallization were also found at Salina and, to a lesser extent, at Alicudi, all situated in the western sector of the Aeolian Arc. The central and eastern islands of Lipari, Vulcano, Panarea and Stromboli generally show higher values of cell parameters, suggesting crystallization in shallow magma chambers. These islands are characterized by the occurrence of large calderas, which are apparently lacking at Salina and Filicudi. Time-related variations were observed for cell and M1 volumes of clinopyroxene for some islands. At Salina, the early-erupted products display low values of cell parameters with respect to later activity, thus indicating a decrease in crystallization pressure with time. A similar, although less striking, pattern is observed at Alicudi and Lipari. An overall increase in cell parameters with time was observed at the scale of the entire arc. The observed variations in clinopyroxene structural parameters highlight the significance of pyroxene crystal chemistry for petrogenetic and volcanological interpretation. Correlation with time and the structural characteristics of volcanoes suggest significant regional and temporal modifications in the plumbing systems of Aeolian volcanoes. Clinopyroxenes from Filicudi and the older Salina crystallized at high

  19. Observation of high coercive fields in chemically synthesized coated Fe-Pt nanostructures

    Science.gov (United States)

    Dalavi, Shankar B.; Panda, Rabi N.

    2017-04-01

    Nanocrystalline Fe-Pt alloys have been synthesized via chemical reduction route using various capping agents; such as: oleic acid/oleylamine (route-1) and oleic acid/CTAB (route-2). We could able to synthesize Fe50Pt and Fe54Pt alloys via route 1 and 2, respectively. As-prepared Fe-Pt alloys crystallize in disordered fcc phase with crystallite sizes of 2.3 nm and 6 nm for route-1 and route-2, respectively. Disordered Fe-Pt alloys were transformed to ordered fct phase after annealing at 600 °C. SEM studies confirm the spherical shape morphologies of annealed Fe-Pt nanoparticles with SEM particle sizes of 24.4 nm and 21.2 nm for route-1 and route-2, respectively. TEM study confirms the presence of 4.6 nm particles for annealed Fe50Pt alloys with several agglomerating clusters of bigger size and appropriately agrees well with the XRD study. Room temperature magnetization studies of as-prepared Fe-Pt alloys (fcc) show ferromagnetism with negligible coercivities. Average magnetic moments per particle for as-prepared Fe-Pt alloys were estimated to be 753 μB and 814 μB, for route 1 and 2, respectively. Ordered fct Fe-Pt alloys show high values of coercivities of 10,000 Oe and 10,792 Oe for route-1 and route-2, respectively. Observed magnetic properties of the fct Fe-Pt alloys nps were interpreted with the basis of order parameters, size, surface, and composition effects.

  20. 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.

  1. 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

  2. Textural and chemical variation in phenocrysts from the early eruptions of Lutao volcanic island, the northern Luzon arc

    Science.gov (United States)

    Liu, Y.; Iizuka, Y.; Huang, K.

    2012-12-01

    The Lutao volcanic island at the northern end of Luzon arc was formed by the subduction of South China Sea Plate beneath the Philippine Sea plate. Three edifices on the island were built up by pyroclastic deposits from different eruption stages. In this study, the textural and chemical zonings in phenocrysts are used to characterize the subvolcanic magma chamber for the earliest eruption stage (1.4-2.0 Ma). The high 143Nd/144Nd and 176Hf/177Hf ratios of six volcanic breccias collected from the lowermost layer indicate that they were derived from a common depleted mantle source. However, their compositional variations cannot be explained by simple fractional crystallization. The textures and compositions of the phenocrysts reveal the complication in the magma chamber processes. Compared to the average primitive arc basalts, two basaltic andesites have similar major element compositions with higher incompatible trace element abundances. The un-zoned or normally zoned olivine, plagioclase, and pyroxenes indicate the relatively undisturbed processes (961-1011°C and 2.8-5.5 kb) at the earlier crystallization stage. The peritectic olivine and abundance melt inclusions accompanied by abrupt XAn increase at the rims of plagioclase inferred recharge of H2O-rich mafic melt at later stage, which also triggered rapid eruption. The cryptic magma mixing had limited effect on isotopic signatures and major element variations, but had great chance to modify the bulk trace element abundances. In contrast, plagioclase phenocrysts in four low-mg# basaltic samples contain An-rich dissolved or resorbed cores with abundant melt inclusions, which were formed from rapid decompression of volatile-rich magma at H2O-undersaturated conditions. The calcic plagioclase and minor Mg-rich olivine formed at greater depth were rapidly brought to magma chamber to crystallized sodic plagioclase rim, clinopyroxene, and minor orthopyroxene (954-994°C and 2.1-4.1 kb). The normally zoned clinopyroxene

  3. Gas and dust productions of comet 103P/Hartley 2 from millimetre observations: interpreting rotation-induced time variations

    CERN Document Server

    Boissier, J; Biver, N; Colom, P; Crovisier, J; Moreno, R; Zakharov, V; Groussin, O; Jorda, L; Lis, D C

    2013-01-01

    Comet 103P/Hartley 2 made a close approach to the Earth in October 2010. It was the target of an extensive observing campaign and was visited by the Deep Impact spacecraft (mission EPOXI). We present observations of HCN and CH3OH 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 coma and nucleus is detected simultaneously. Interferometric images with unprecedented spatial resolution are obtained. A sine-wave variation of the thermal continuum is observed in the 23 October data, that we associate with the nucleus thermal light curve. The nucleus contributes up to 30-55 % of the observed continuum. The large dust-to-gas ratio (in the range 2-6) can be explained by the unusual activity of the comet for its size, which allows decimeter size particles and large boulders to be entrained by the gas. The rotational temperature of CH3OH is measured. We attribute the increase from 35 to...

  4. Multi-scale Drivers of Variations in Atmospheric Evaporative Demand Based on Observations and Physically-based Modeling

    Science.gov (United States)

    Peng, L.; Sheffield, J.; Li, D.

    2015-12-01

    Evapotranspiration (ET) is a key link between the availability of water resources and climate change and climate variability. Variability of ET has important environmental and socioeconomic implications for managing hydrological hazards, food and energy production. Although there have been many observational and modeling studies of ET, how ET has varied and the drivers of the variations at different temporal scales remain elusive. Much of the uncertainty comes from the atmospheric evaporative demand (AED), which is the combined effect of radiative and aerodynamic controls. The inconsistencies among modeled AED estimates and the limited observational data may originate from multiple sources including the limited time span and uncertainties in the data. To fully investigate and untangle the intertwined drivers of AED, we present a spectrum analysis to identify key controls of AED across multiple temporal scales. We use long-term records of observed pan evaporation for 1961-2006 from 317 weather stations across China and physically-based model estimates of potential evapotranspiration (PET). The model estimates are based on surface meteorology and radiation derived from reanalysis, satellite retrievals and station data. Our analyses show that temperature plays a dominant role in regulating variability of AED at the inter-annual scale. At the monthly and seasonal scales, the primary control of AED shifts from radiation in humid regions to humidity in dry regions. Unlike many studies focusing on the spatial pattern of ET drivers based on a traditional supply and demand framework, this study underlines the importance of temporal scales when discussing controls of ET variations.

  5. 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

  6. Physical and chemical variations within the W3 star-forming region. II. The 345 GHz spectral line survey.

    Science.gov (United States)

    Helmich, F. P.; van Dishoeck, E. F.

    1997-08-01

    Results are presented of the 345 GHz spectral survey toward three sources in the W3 Giant Molecular Cloud: W3 IRS4, W3 IRS5 and W3(H_2O). Nearly 90% of the atmospheric window between 334 and 365 GHz has been scanned using the James Clerk Maxwell Telescope down to a noise level of ~80 mK per resolution element. These observations are complemented by a large amount of data in the 230 GHz atmospheric window. From this data set physical conditions and beam-averaged column densities are derived for more than 14 chemically different species (over 24 different isotopes). The physical parameters derived in Paper I (\\cite[Helmich et al. 1994]{ref36}) are confirmed by the analysis of the excitation of other species, although there is evidence that the silicon- and sulfur-bearing molecules exist in a somewhat denser and warmer environment. The densities are high, >= 10^6 cm^{-3}, in the three sources and the kinetic temperatures for the bulk of the gas range from 55 K for IRS4 to 220 K for W3(H_2O). The chemical differences between the three sources are very striking: silicon- and sulfur-bearing molecules such as SiO and SO_2 are prominent toward IRS5, whereas organic molecules like CH_3OH, CH_3OCH_3 and CH_3OCHO are at least an order of magnitude more abundant toward W3(H_2O). Vibrationally excited molecules are also detected toward this source. Only simple molecules are found toward IRS4. The data provide constraints on the amount of deuterium fractionation and the ionization fraction in the observed regions as well. These chemical characteristics are discussed in the context of an evolutionary sequence, in which IRS5 is the youngest, W3(H_2O) somewhat older and IRS4, although still enigmatic, the oldest. The James Clerk Maxwell Telescope is operated by the The Joint Astronomy Centre on behalf of the Particle Physics and Astronomy Research Council of the United Kingdom, the Netherlands Organisation for Scientific Research, and the National Research Council of Canada

  7. 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.

  8. Causes of variation in soil carbon simulations from CMIP5 Earth system models and comparison with observations

    Directory of Open Access Journals (Sweden)

    K. E. O. Todd-Brown

    2013-03-01

    soil carbon when driven by observations of NPP and temperature, implying that other drivers or processes may be more important in explaining observed soil carbon distributions. The reduced complexity model also showed that differences in simulated soil carbon across ESMs were driven by differences in simulated NPP and the parameterization of soil heterotrophic respiration (inter-model R2 = 0.93, not by structural differences between the models. Overall, our results suggest that despite fair global-scale agreement with observational data and moderate agreement at the biome scale, most ESMs cannot reproduce grid-scale variation in soil carbon and may be missing key processes. Future work should focus on improving the simulation of driving variables for soil carbon stocks and modifying model structures to include additional processes.

  9. 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.

  10. Transient deformation of karst aquifers due to seasonal and multiyear groundwater variations observed by GPS in southern Apennines (Italy)

    Science.gov (United States)

    Silverii, Francesca; D'Agostino, Nicola; Métois, Marianne; Fiorillo, Francesco; Ventafridda, Gerardo

    2016-11-01

    We present GPS, hydrological, and GRACE (Gravity Recovery and Climate Experiment) observations in southern Apennines (Italy) pointing to a previously unnoticed response of the solid Earth to hydrological processes. Transient patterns in GPS horizontal time series near to large karst aquifers are controlled by seasonal and interannual phases of groundwater recharge/discharge of karst aquifers, modulating the extensional ˜3 mm/yr strain within the tectonically active Apennines. We suggest that transient signals are produced, below the saturation level of the aquifers and above a poorly constrained depth in the shallow crust, by time-dependent opening of subvertical, fluid-filled, conductive fractures. We ascribe this process to the immature karstification and intense tectonic fracturing, favoring slow groundwater circulation, and to multiyear variations of the water table elevation, influenced by variable seasonal recharge. The vertical component displays seasonal and multiyear signals more homogeneously distributed in space and closely correlated with estimates of total water storage from GRACE, reflecting the elastic response of the lithosphere to variations of surface water loads. The different sensitivities of vertical and horizontal components to the hydrologically induced deformation processes allow us to spatially and temporally resolve the different phases of the water cycle, from maximum hydrological loading at the surface to maximum hydrostatic pressure beneath karst aquifers. Finally, we suggest that transient deformation signals in the geodetic series of the Apennines are correlated to large-scale climatic patterns (Northern Atlantic Oscillation) through their influence on precipitation variability and trends at the regional scale.

  11. 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

  12. Chemical variation of essential oil constituents of Ocimum gratissimum L. from Benin, and impact on antimicrobial properties and toxicity against Artemia salina leach.

    Science.gov (United States)

    Kpadonou Kpoviessi, Bénédicta G H; Ladekan, Eléonore Yayi; Kpoviessi, D S Salomé; Gbaguidi, Fernand; Yehouenou, Boniface; Quetin-Leclercq, Joëlle; Figueredo, Gilles; Moudachirou, Mansourou; Accrombessi, Georges C

    2012-01-01

    To determine the period of harvest that optimizes the antimicrobial activities of the essential oil of Ocimum gratissimum L. from Benin, aerial plant parts were collected at two vegetative stages (pre- and full-flowering) and three sampling times (7 am, 1 pm, and 7 pm). Extraction by hydrodistillation yielded between 0.65 and 0.78% of essential oils. Characterization of the oils by GC-FID and GC/MS analysis revealed the presence of monoterpenes (87.26-93.81%), sesquiterpenes (5.57-11.34%), and aliphatic compounds (0.15-0.18%), with p-cymene (1; 28.08-53.82%), thymol (2; 3.32-29.13%), γ-terpinene (3; 1.11-10.91%), α-thujene (4; 3.37-10.77%), and β-myrcene (5; 4.24-8.28%) as major components. Two chemotypes were observed, i.e., a p-cymene/thymol and a p-cymene chemotype, for plants harvested at 7 am for the former and at 1 pm or 7 pm for the latter, respectively. The oils were fungicidal against Candida albicans, with the sample from full-flowering plants collected at 7 am being the most active (MIC = 0.06±0.00 mg/ml). The chemical variation of the oils also influenced the antimicrobial effect against Staphylococcus aureus; the most active oil was obtained from plants at the pre-flowering stage collected at 7 am (MIC=0.24±0.01 mg/ml). Escherichia coli was insensitive to the chemical variation of the oils (MICs of ca. 0.48±0.02 mg/ml for all oils). Moreover, the essential oils showed low toxicity against Artemia salina Leach larvae, with LC(50) values in the range of 43-146 μg/ml. This is the first study of the interaction between the daytime of collection and vegetative stage of the plants and the antimicrobial properties and toxicity of the essential oil of O. gratissimum from Benin.

  13. STUDY ON VARIATION CHARACTERISTICS OF SST OBSERVED IN THE PAST 40 YEARS IN THE COASTAL REGION OF SOUTH CHINA

    Institute of Scientific and Technical Information of China (English)

    PAN Wei-juan; QIAN Guang-ming; YU Ke-fu; CHEN Te-gu

    2007-01-01

    To study the variation characteristics of SST in coastal south China, observed SST was analyzed for the past 44 years. The results show that the monthly and yearly averaged SST have rising trends, the yearly averaged SST's linearity rising rate is 0.12-0.19 ℃/decade in the years, the rising extents in winter are higher than those in summer. The variability in winter is larger than that in summer, with the largest in February and March. A majority of significant cold or warm events occurred in winter. A wavelet multiresolution method was used to analyze periodical characteristics of SST in coastal south China, all timescale decomposition series are very similar, and high-frequency decompositions within the year are dominant. Low-frequency decompositions show rising trends since the mid-1970.

  14. 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

    The quality of Earth observation (EO) based vegetation monitoring has improved during recent years, which can be attributed to the enhanced sensor design of new satellites such as MODIS (Moderate Resolution Imaging Spectroradiometer) on Terra and Aqua. It is however expected that sun-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...... viewing geometry on red, near-infrared (NIR) and NDVI needs to be quantified. Data from the geostationary MSG (Meteosat Second Generation) SEVIRI (Spinning Enhanced Visible and Infrared Imager) sensor is well suited for this purpose due to the fixed position of the sensor, the spectral resolution...

  15. Infrasound observations at Syowa Station, East Antarctica: Implications for detecting the surface environmental variations in the polar regions

    Directory of Open Access Journals (Sweden)

    Yoshiaki Ishihara

    2015-03-01

    Full Text Available Characteristic infrasound waves observed at Antarctic stations demonstrate physical interaction involving environmental changes in the Antarctic continent and the surrounding oceans. A Chaparral-type infrasound sensor was installed at Syowa Station (SYO; 39°E, 69°S, East Antarctica, as one of the projects of the International Polar Year (IPY2007‒2008. Data continuously recorded during the three seasons in 2008–2010 clearly indicate a contamination of the background oceanic signals (microbaroms with peaks between 4 and 10 s observed during a whole season. The peak amplitudes of the microbaroms have relatively lower values during austral winters, caused by a larger amount of sea-ice extending around the Lützow-Holm Bay near SYO, with decreasing ocean wave loading effects. Microbaroms measurements are useful tool for characterizing ocean wave climate, complementing other oceanographic and geophysical data. A continuous monitoring by infrasound sensors in the Antarctic firmly contributes to the Comprehensive Nuclear-Test-Ban Treaty (CTBT in the southern high latitude, together with the Pan-Antarctic Observations System (PAntOS under the Scientific Committee on Antarctic Research (SCAR. Detailed measurements of the infrasound waves in Antarctica, consequently, could be a new proxy for monitoring regional environmental change as well as the temporal climate variations in the polar regions.

  16. 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...

  17. Seasonal variation of trace gas compounds and PM2.5 observed at an urban supersite in Beijing

    Science.gov (United States)

    Wu, Yusheng; Hu, Min; Zeng, Limin; Dong, Huabin; Li, Xin; Lu, Keding; Lu, Sihua; Yang, Yudong; Zhang, Yuanhang

    2016-04-01

    The air pollution in Beijing has been a growing concern in the last ten years. We have performed measurements on trace gas compounds (CO, NOx, NOy, O3, SO2), PM2.5, and meteorological parameters at Beijing urban Atmospheric Environmental Observation Station in the campus of Peking University for more than ten years. The measurement results provide us an opportunity to track the air quality change in downtown Beijing. Here, we present observations during year between 2011 and 2015. The annual averaged concentration of CO, NOx, NOy, O3, SO2, and PM2.5 is 1.2 ± 0.1 ppm, 49.9 ± 5.9 ppb, 54.6 ± 4.7 ppb, 26.1 ± 3.8 ppb, 10.6 ± 2.9 ppb, and 53.4 ± 9.8 μg ṡm-3, respectively. A clear seasonal variation is identified for all the measured trace gas compounds and PM2.5, CO, NOx, NOy, SO2, and PM2.5 show their maximum in winter and minimum in summer. Whilst O3 shows an inverse pattern. This result indicates that the air pollution in Beijing is characterized by haze in winter but by photochemical smog in summer. The effects of meteorological conditions and emissions on the occurrence of pollution episode are discussed in details based on the long-term observation data set.

  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. Constraints on Anthropogenic NOx Emissions from Geostationary Satellite Observations in a Regional Chemical Data Assimilation System: Evaluation Using Observing System Simulation Experiments

    Science.gov (United States)

    Liu, X.; Mizzi, A. P.; Anderson, J. L.; Fung, I. Y.; Cohen, R. C.

    2015-12-01

    Nitrogen oxides (NOx=NO+NO2) control the tropospheric ozone (O3) budget, the abundance of the hydroxyl radical (OH), the formation of organic and inorganic nitrate aerosol, and therefore affect air quality and climate. There remain significant uncertainties in the processes responsible for NOx emissions and subsequent mixing and chemical removal. NOx has a short lifetime and its emissions show high spatiotemporal variability at urban scale. Future geostationary satellite instruments including TEMPO, GEMS and Sentinel-4 will provide hourly time resolution and high spatial resolution observations providing maps of NO2 on diurnal and local scales. Here we determine the extent to which a TEMPO like instrument can quantify urban-scale NOx emissions using a regional data assimilation (DA) system comprising of a chemical transport model, WRF-Chem, a TEMPO simulator and the DART Ensemble Adjustment Kalman Filter. We generate synthetic TEMPO observations by sampling from a nature run on an urban scale domain. We consider the effect of albedo, surface pressure, solar and viewing angles and a priori NO2 profiles on the TEMPO NO2 averaging kernel to achieve scene-dependent instrument sensitivity. We estimate NOx emissions using DART in a state augmentation approach by including NOx emissions in the state vector being analyzed. The ensemble-based statistical estimation of error correlations between concentrations and emissions are critical as they determine the impact of assimilated observations. We describe observing system simulation experiments to explore the optimal approach in the ensemble-based DA system to estimate hourly-resolved NOx emissions from TEMPO NO2 observations. Several case studies will be presented examining the role of covariance localization length and chemical perturbations on the success of the approach.

  20. Research upon the quality assurance of the rolling-mill rolls and the variation boundaries of the chemical composition

    Directory of Open Access Journals (Sweden)

    Kiss, I.

    2008-08-01

    Full Text Available The cast-iron rolls must present higher hardness at the rolling surface and lower in the core and the necks, adequate with mechanical resistance and in the high work temperature. If in the zone of the rolling surface, the hardness is guarantied by the irons structure, through the cementite quantities, the core of rolls must contain graphite, to assure this property. Starting from the lamination equipments aspects, from the form of rolls, of the technological interest zones and the structure, which assures the exploitation property, it was establish, through modeling, to the mathematical description of a direct influences, and in final, through successive determinations, to an optimum. One of the parameters, which are determined the structure of the irons destined for rolls casting, is the chemical composition, which guaranties the exploitation properties of the each roll in the stand of rolling mill. The realization of optimum chemical compositions of the cast-iron can constitute a technical efficient way to assure the exploitation properties, the material from which the rolling mills rolls are manufactured having an important role in this sense. Although the manufacture of rolls is in continuously perfecting, the requirements for superior quality rolls are not yet completely satisfied, in many cases, the absence of quality rolls preventing the realization of quality laminates or the realization of productivities of which rolling mills are capable. This paper presents an analysis of the main alloying elements from chemical composition, the influences upon the mechanical properties of the cast-iron rolls, and presents also some graphical addenda. Using the Matlab calculation and graphical programs we determinate some correlations between the hardness (on the working surface and on necks and the chemical composition. Using the double and triple correlations is really helpful in the foundry practice, as it allows us to determine variation

  1. 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

    Using a combination of complementary in situ X-ray photoelectron spectroscopy and X-ray diffraction, we study the fundamental mechanisms underlying the chemical vapor deposition (CVD) of hexagonal boron nitride (h-BN) on polycrystalline Cu. The nucleation and growth of h-BN layers is found to occ...

  2. Tidally induced variations in vertical and horizontal motion on Rutford Ice Stream, West Antarctica, inferred from remotely sensed observations

    Science.gov (United States)

    Minchew, B. M.; Simons, M.; Riel, B.; Milillo, P.

    2017-01-01

    To better understand the influence of stress changes over floating ice shelves on grounded ice streams, we develop a Bayesian method for inferring time-dependent 3-D surface velocity fields from synthetic aperture radar (SAR) and optical remote sensing data. Our specific goal is to observe ocean tide-induced variability in vertical ice shelf position and horizontal ice stream flow. Thus, we consider the special case where observed surface displacement at a given location can be defined by a 3-D secular velocity vector, a family of 3-D sinusoidal functions, and a correction to the digital elevation model used to process the SAR data. Using nearly 9 months of SAR data collected from multiple satellite viewing geometries with the COSMO-SkyMed 4-satellite constellation, we infer the spatiotemporal response of Rutford Ice Stream, West Antarctica, to ocean tidal forcing. Consistent with expected tidal uplift, inferred vertical motion over the ice shelf is dominated by semidiurnal and diurnal tidal constituents. Horizontal ice flow variability, on the other hand, occurs primarily at the fortnightly spring-neap tidal period (Msf). We propose that periodic grounding of the ice shelf is the primary mechanism for translating vertical tidal motion into horizontal flow variability, causing ice flow to accelerate first and most strongly over the ice shelf. Flow variations then propagate through the grounded ice stream at a mean rate of ˜29 km/d and decay quasi-linearly with distance over ˜85 km upstream of the grounding zone.

  3. The centre-to-limb variations of solar Fraunhofer lines imprinted upon lunar eclipse spectra - Implications for exoplanet transit observations

    CERN Document Server

    Yan, Fei; Petr-Gotzens, Monika G; Zhao, Gang; Pallé, Enric

    2015-01-01

    The atmospheres of exoplanets are commonly studied by observing the transit of the planet passing in front of its parent star. The obscuration of part of the stellar disk during a transit will reveal aspects of its surface structure resulting from general centre-to-limb variations (CLVs). These become apparent when forming the ratio between the stellar light in and out of transit. These phenomena can be seen particularly clearly during the progress of a penumbral lunar eclipse, where the Earth transits the solar disk and masks different regions of the solar disk as the eclipse progresses. When inferring the properties of the planetary atmosphere, it is essential that this effect originating at the star is properly accounted for. Using the data observed from the 2014-April-15 lunar eclipse with the ESPaDOnS spectrograph mounted on the Canada France Hawaii Telescope (CFHT), we have obtained for the first time a time sequence of the penumbral spectra. These penumbral spectra enable us to study the centre-to-limb...

  4. Spectral and temporal variations of the isolated neutron star RX J0720.4-3125: new XMM-Newton observations

    CERN Document Server

    Hohle, M M; Vink, J; Hambaryan, V; Turolla, R; Zane, S; De Vries, C P; Méndez, M

    2008-01-01

    In the past, the isolated, radio-quiet neutron star RX J0720.4-3125 showed variations in the spectral parameters (apparent radius, temperature of the emitting area and equivalent width of the absorption feature) seen in the X-ray spectra, not only during the spin period of 8.39s, but also over time scales of years. New X-ray observations of RX J0720.4-3125 with XMM Newton extend the coverage to about 7.5 years with the latest pointing performed in November 2007. Out of a total of fourteen available EPIC-pn datasets, eleven have been obtained with an identical instrumental setup (full frame read-out mode with thin filter), and are best suited for a comparative investigations of the spectral and timing properties of this enigmatic X-ray pulsar. We analysed the new XMM Newton observations together with archival data in order to follow the spectral and temporal evolution of RX J0720.4-3125 All XMM-Newton data were reduced with the standard XMM-SAS software package. A systematic and consistent data reduction of al...

  5. Chemical variations in the Triple Group of the Skaergaard intrusion: insights for the mineralization and crystallization process

    Science.gov (United States)

    Nielsen, T. F.; Bernstein, S.

    2009-12-01

    The 54 Ma. old Skaergaard intrusion ( East Greenland) is a type example for fractionation of basaltic melt along the Fenner Trend. The Triple Group is the upper most 100 m of the Middle Zone and consists of FeTi-oxide rich layered gabbro with three distinct leugabbro layers 2-5 m thick ( L-layers; L1-L3, 2-5m thick) and a less marked layer (L0) c.20 m below L1. These are the most marked of many such layers. Apart from the pronounced layering the lower part of the Triple Group also hosts a world class Au-PGE mineralization. The mineralization is perfectly concordant with the L-layers, and the Triple Group invites investigation of the relationship between host and mineralization. The mineralization includes 5 main levels defined by palladium concentration. The chemical variation across the mineralization is covered by ca. 250 bulk major and trace element compositions, each representing 25cm of stratigraphy giving a continuum of ca. 60m. Proportions of normative plagioclase (plag) and pyroxene (px, including cpx and opx) are complementary, except in mineralized gabbro which is rich in FeTi-oxides. Cumulus ilmenite (ilm) is strongly enriched in layers (7m apart). They occur in both plag- and px-rich gabbro, whereas magnetite (mt) shows no simple correlation with ilm and is mainly a poikilitic intercumulus phase. The L-layers are composed of an upper part rich in plag and px and poor in FeTi-oxides, and a lower part rich in plag and FeTi-oxides and poor in px. The marked breaks in the mineralogy in the L-layers separate one layered succession from the next. The layered successions consist of a lower oxide-poor px-plag adcumulate, followed by complex mesocratic orthocumulate with poikilitic interstitial FeTi-oxide, and an upper part of increasingly simple plag-rich adcumulate with decreasing content of interstitial mt. The Au-PGE mineralized levels are found in the complex FeTi-rich gabbros at and in the base of the leucogabbro layers. The stratigraphic variation in

  6. Chemical and U-Sr isotopic variations in stream and source waters of the Strengbach watershed (Vosges mountains, France)

    Science.gov (United States)

    Pierret, M. C.; Stille, P.; Prunier, J.; Viville, D.; Chabaux, F.

    2014-10-01

    This is the first comprehensive study dealing with major and trace element data as well as 87Sr/86Sr isotope and (234U/238U) activity ratios (AR) determined on the totality of springs and brooks of the Strengbach catchment. It shows that the small and more or less monolithic catchment drains different sources and streamlets with very different isotopic and geochemical signatures. Different parameters control the diversity of the source characteristics. Of importance is especially the hydrothermal overprint of the granitic bedrock, which was stronger for the granite from the northern slope; also significant are the different meteoric alteration processes of the bedrock causing the formation of 0.5 to 9 m thick saprolite and above the formation of an up to 1m thick soil system. These processes mainly account for springs and brooks from the northern slope having higher Ca / Na, Mg / Na, and Sr / Na ratios, but lower 87Sr/86Sr isotopic ratios than those from the southern slope. The chemical compositions of the source waters in the Strengbach catchment are only to a small extent the result of alteration of primary bedrock minerals, and rather reflect dissolution/precipitation processes of secondary mineral phases like clay minerals. The (234U/238U) AR, however, are decoupled from the 87Sr/86Sr isotope system, and reflect to some extent the level of altitude of the source and, thus, the degree of alteration of the bedrock. The sources emerging at high altitudes have circulated through already weathered materials (saprolite and fractured bedrock depleted in 234U), implying (234U/238U) AR below 1, which is uncommon for surface waters. Preferential flow paths along constant fractures in the bedrocks might explain the - over time - homogeneous U AR of the different spring waters. However, the geochemical and isotopic variations of stream waters at the outlet of the catchment are controlled by variable contributions of different springs, depending on the hydrological

  7. Seasonal Variation of the Chemical Composition and Antimicrobial and Cytotoxic Activities of the Essential Oils from Inga laurina (Sw. Willd.

    Directory of Open Access Journals (Sweden)

    Fabiana B. Furtado

    2014-04-01

    Full Text Available The seasonal chemical composition of essential oils from Inga laurina was determined by GC/MS. In the stem bark’s essential oil extracted during the dry season, the presence of terpenoids (30.05% stood out, and phytol (9.76% was the major compound identified. For the stem bark oil obtained during the rainy season, in addition to terpenoids (26.63%, a large amount of fatty acids (46.84% were identified, in particular palmitic acid (25.40%. Regarding the leaves’ essential oil obtained in the dry season, esters (42.35% were the main components. The main ester present was (Z-hex-3-enyl benzoate (10.15% and the major compound of this oil was (Z-hex-3-en-1-ol (14.23%. Terpenoids (33.84%, long-chain alkanes (27.04% and fatty acids (21.72% were the main components of the essential oil from leaves in the rainy season. Phytol (33.21%, nonacosane (21.95% and palmitic acid (15.20% were the major compounds identified. The antimicrobial activity against aerobic and anaerobic oral bacteria was evaluated by the microdilution broth method and cytotoxic activity was carried out with Vero cells. The essential oils from the rainy season showed a better inhibition of the bacterial growth with Minimal Inhibitory Concentrations (MIC values of 25 or 50 µg·mL−1 for aerobic bacteria, and high selectivity against bacteria was observed. The large amount of fatty acids in rainy season oils may be related to the better inhibitory effects observed.

  8. Particulate pollution in urban Chongqing of southwest China: Historical trends of variation, chemical characteristics and source apportionment.

    Science.gov (United States)

    Chen, Yuan; Xie, Shao-Dong; Luo, Bin; Zhai, Chong-Zhi

    2017-04-15

    Chongqing, the largest megacity in southwest China, faces serious aerosol pollution but lacks information on particle characteristics and its sources. Official data released by Chongqing Environmental Protection Bureau demonstrated that urban PM10 concentrations decreased remarkably from 150μgm(-3) in 2000 to 90μgm(-3) in 2012. However, only several peer-reviewed studies paid attention to local fine particle (PM2.5) pollution. In the study, PM2.5 samples were obtained and subjected to chemical analysis in an urban site of the city during 2012 to 2013. The annual mean PM10 and PM2.5 concentrations in urban Chongqing were 103.9±52.5 and 75.4±42.2μgm(-3), respectively. PM2.5 showed a distinct seasonality of high concentration in winter and similar levels in other seasons. The average OC/EC (organic carbon/element carbon) ratio was 3.7 with more high-OC/EC ratio sources contribution in autumn and winter. The varying sources and formation mechanisms resulted in SO4(2-) and NH4(+) peaks in both summer and winter, whereas high nitrate concentration was only observed in winter. In the average mass closure, PM2.5 was composed of 23.0% SO4(2-), 11.7% NO3(-), 10.9% NH4(+), 30.8% OM (organic matter), 5.2% EC, 8.2% mineral dust, 0.6% TEO (trace elements), 1.0% Cl(-) and 1.1% K(+), while exhibiting large seasonal variability. Using positive matrix factorization (PMF), six sources were apportioned in PM2.5: secondary inorganic aerosols, coal combustion, other industrial pollution, soil dust, vehicular emission, and metallurgical industry. The annual mean contribution of above sources to PM2.5 was 37.5, 22.0, 17.5, 11.0, 9.8 and 2.2%, respectively. Coal combustion was identified by As tracer and dominated the primary sources of PM2.5, while the two different industrial sources were characterized by Cr and Mo, Co, Ni, and Se, respectively. The study is of great importance in characterizing the historical trends, current chemical characteristics and sources of fine particles in

  9. 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.

  10. Variations of magnetic bright point properties with longitude and latitude as observed by Hinode/SOT G-band data

    CERN Document Server

    Utz, D; Veronig, A; Kühner, O; Muller, R; Jurčák, J; Lemmerer, B; 10.1007/s11207-012-0210-7

    2012-01-01

    Small-scale magnetic fields can be observed on the Sun in high resolution G-band filtergrams as magnetic bright points (MBPs). We study Hinode/ Solar Optical Telescope (SOT) longitude and latitude scans of the quiet solar surface taken in the G-band in order to characterise the centre-to-limb dependence of MBP properties (size and intensity). We find that the MBP's sizes increase and their intensities decrease from the solar centre towards the limb. The size distribution can be fitted using a log-normal function. The natural logartihm of the mean (parameter \\mu) of this function follows a second-order polynomial and the generalised standard deviation (parameter \\sigma) follows a fourth-order polynomial or equally well (within statistical errors) a sine function. The brightness decrease of the features is smaller than one would expect from the normal solar centre-to-limb variation; that is to say, the ratio of a MBP's brightness to the mean intensity of the image increases towards the limb. The centre-to-limb ...

  11. Validation of terrestrial water storage variations as simulated by different global numerical models with GRACE satellite observations

    Science.gov (United States)

    Zhang, Liangjing; Dobslaw, Henryk; Stacke, Tobias; Güntner, Andreas; Dill, Robert; Thomas, Maik

    2017-02-01

    Estimates of terrestrial water storage (TWS) variations from the Gravity Recovery and Climate Experiment (GRACE) satellite mission are used to assess the accuracy of four global numerical model realizations that simulate the continental branch of the global water cycle. Based on four different validation metrics, we demonstrate that for the 31 largest discharge basins worldwide all model runs agree with the observations to a very limited degree only, together with large spreads among the models themselves. Since we apply a common atmospheric forcing data set to all hydrological models considered, we conclude that those discrepancies are not entirely related to uncertainties in meteorologic input, but instead to the model structure and parametrization, and in particular to the representation of individual storage components with different spatial characteristics in each of the models. TWS as monitored by the GRACE mission is therefore a valuable validation data set for global numerical simulations of the terrestrial water storage since it is sensitive to very different model physics in individual basins, which offers helpful insight to modellers for the future improvement of large-scale numerical models of the global terrestrial water cycle.

  12. Anomalous diurnal variation of atmospheric potential gradient and air-Earth current density observed at Maitri, Antarctica

    Science.gov (United States)

    Jeeva, K.; Gurubaran, S.; Williams, E. R.; Kamra, A. K.; Sinha, A. K.; Guha, A.; Selvaraj, C.; Nair, K. U.; Dhar, Ajay

    2016-11-01

    The scope of this paper is to explore the mechanisms operating over Maitri (70.76°S, 11.74°E, 117 m above mean sea level), a coastal Antarctic station, that produce an anomalous fair-weather diurnal pattern of the atmospheric electric potential gradient (PG) and air-Earth current density (AEC). The anomaly in the diurnal variations of AEC and the PG is displaying an ostensible minimum at 10 UT and a diminished response to the thunderstorm over the African continent in the 14-16 UT time frame. The data sets (2005-2014, except 2012) of the PG, and to some extent, AEC, from Maitri, are used to explore this anomaly. It follows that the fair-weather electrical phenomena over Maitri can be ascribed to global electrified convection on the one hand and to regional phenomena like convection due to the replacement of warm air by katabatic winds on the other hand. The katabatic winds originate on the polar plateau and blow from 130° at Maitri which are likely to transport various elements from the mountain slopes, and space charge from the polar plateau is expected to produce various disturbances in the PG and AEC monitored over the coastal Antarctica. This mechanism may be responsible for peaks in the early UT hours and also for the anomalous behavior of atmospheric electrical parameters observed at Maitri. Maitri data are compared with that of Carnegie cruise and Vostok to explain the source of anomaly.

  13. Interspecific variation in persistence of buried weed seeds follows trade-offs among physiological, chemical and physical seed defences

    Science.gov (United States)

    Soil seedbanks drive infestations of annual weeds, yet weed management focuses largely on seedling mortality. As weed seedbanks increasingly become reservoirs of herbicide resistance, species-specific seedbank management approaches will be essential. Limited understanding of interspecific variation ...

  14. 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.

  15. Multi-path variational transition state theory for chemical reaction rates of complex polyatomic species: ethanol + OH reactions.

    Science.gov (United States)

    Zheng, Jingjing; Truhlar, Donald G

    2012-01-01

    Complex molecules often have many structures (conformations) of the reactants and the transition states, and these structures may be connected by coupled-mode torsions and pseudorotations; some but not all structures may have hydrogen bonds in the transition state or reagents. A quantitative theory of the reaction rates of complex molecules must take account of these structures, their coupled-mode nature, their qualitatively different character, and the possibility of merging reaction paths at high temperature. We have recently developed a coupled-mode theory called multi-structural variational transition state theory (MS-VTST) and an extension, called multi-path variational transition state theory (MP-VTST), that includes a treatment of the differences in the multi-dimensional tunneling paths and their contributions to the reaction rate. The MP-VTST method was presented for unimolecular reactions in the original paper and has now been extended to bimolecular reactions. The MS-VTST and MP-VTST formulations of variational transition state theory include multi-faceted configuration-space dividing surfaces to define the variational transition state. They occupy an intermediate position between single-conformation variational transition state theory (VTST), which has been used successfully for small molecules, and ensemble-averaged variational transition state theory (EA-VTST), which has been used successfully for enzyme kinetics. The theories are illustrated and compared here by application to three thermal rate constants for reactions of ethanol with hydroxyl radical--reactions with 4, 6, and 14 saddle points.

  16. PM2.5 in the Yangtze River Delta, China: Chemical compositions, seasonal variations, and regional pollution events.

    Science.gov (United States)

    Ming, Lili; Jin, Ling; Li, Jun; Fu, Pingqing; Yang, Wenyi; Liu, Di; Zhang, Gan; Wang, Zifa; Li, Xiangdong

    2017-04-01

    Fine particle (PM2.5) samples were collected simultaneously at three urban sites (Shanghai, Nanjing, and Hangzhou) and one rural site near Ningbo in the Yangtze River Delta (YRD) region, China, on a weekly basis from September 2013 to August 2014. In addition, high-frequency daily sampling was conducted in Shanghai and Nanjing for one month during each season. Severe regional PM2.5 pollution episodes were frequently observed in the YRD, with annual mean concentrations of 94.6 ± 55.9, 97.8 ± 40.5, 134 ± 54.3, and 94.0 ± 57.6 μg m(-3) in Shanghai, Nanjing, Hangzhou, and Ningbo, respectively. The concentrations of PM2.5 and ambient trace metals at the four sites showed clear seasonal trends, with higher concentrations in winter and lower concentrations in summer. In Shanghai, similar seasonal patterns were found for organic carbon (OC), elemental carbon (EC), and water-soluble inorganic ions (K(+), NH4(+), Cl(-), NO3(-), and SO4(2-)). Air mass backward trajectory and potential source contribution function (PSCF) analyses implied that areas of central and northern China contributed significantly to the concentration and chemical compositions of PM2.5 in Shanghai during winter. Three heavy pollution events in Shanghai were observed during autumn and winter. The modelling results of the Nested Air Quality Prediction Modeling System (NAQPMS) showed the sources and transport of PM2.5 in the YRD during the three pollution processes. The contribution of secondary species (SOC, NH4(+), NO3(-), and SO4(2-)) in pollution event (PE) periods was much higher than in BPE (before pollution event) and APE (after pollution event) periods, suggesting the importance of secondary aerosol formation during the three pollution events. Furthermore, the bioavailability of Cu, and Zn in the wintertime PM2.5 samples from Shanghai was much higher during the pollution days than during the non-pollution days.

  17. Collocated observations of cloud condensation nuclei, particle size distributions, and chemical composition

    Science.gov (United States)

    Schmale, Julia; Henning, Silvia; Henzing, Bas; Keskinen, Helmi; Sellegri, Karine; Ovadnevaite, Jurgita; Bougiatioti, Aikaterini; Kalivitis, Nikos; Stavroulas, Iasonas; Jefferson, Anne; Park, Minsu; Schlag, Patrick; Kristensson, Adam; Iwamoto, Yoko; Pringle, Kirsty; Reddington, Carly; Aalto, Pasi; Äijälä, Mikko; Baltensperger, Urs; Bialek, Jakub; Birmili, Wolfram; Bukowiecki, Nicolas; Ehn, Mikael; Fjæraa, Ann Mari; Fiebig, Markus; Frank, Göran; Fröhlich, Roman; Frumau, Arnoud; Furuya, Masaki; Hammer, Emanuel; Heikkinen, Liine; Herrmann, Erik; Holzinger, Rupert; Hyono, Hiroyuki; Kanakidou, Maria; Kiendler-Scharr, Astrid; Kinouchi, Kento; Kos, Gerard; Kulmala, Markku; Mihalopoulos, Nikolaos; Motos, Ghislain; Nenes, Athanasios; O’Dowd, Colin; Paramonov, Mikhail; Petäjä, Tuukka; Picard, David; Poulain, Laurent; Prévôt, André Stephan Henry; Slowik, Jay; Sonntag, Andre; Swietlicki, Erik; Svenningsson, Birgitta; Tsurumaru, Hiroshi; Wiedensohler, Alfred; Wittbom, Cerina; Ogren, John A.; Matsuki, Atsushi; Yum, Seong Soo; Myhre, Cathrine Lund; Carslaw, Ken; Stratmann, Frank; Gysel, Martin

    2017-01-01

    Cloud condensation nuclei (CCN) number concentrations alongside with submicrometer particle number size distributions and particle chemical composition have been measured at atmospheric observatories of the Aerosols, Clouds, and Trace gases Research InfraStructure (ACTRIS) as well as other international sites over multiple years. Here, harmonized data records from 11 observatories are summarized, spanning 98,677 instrument hours for CCN data, 157,880 for particle number size distributions, and 70,817 for chemical composition data. The observatories represent nine different environments, e.g., Arctic, Atlantic, Pacific and Mediterranean maritime, boreal forest, or high alpine atmospheric conditions. This is a unique collection of aerosol particle properties most relevant for studying aerosol-cloud interactions which constitute the largest uncertainty in anthropogenic radiative forcing of the climate. The dataset is appropriate for comprehensive aerosol characterization (e.g., closure studies of CCN), model-measurement intercomparison and satellite retrieval method evaluation, among others. Data have been acquired and processed following international recommendations for quality assurance and have undergone multiple stages of quality assessment. PMID:28291234

  18. Between and within-field variation in physico-chemical soil properties of vineyards: implications for terroir zoning and management in Heuvelland, Belgium

    Science.gov (United States)

    Tavernier, Emma; Verdoodt, Ann; Cornelis, Wim; Delbecque, Nele; Tiebergijn, Lynn; Seynnaeve, Marleen; Gabriels, Donald

    2015-04-01

    The 'Heuvelland' region with a surface area of 94 km² is situated in the Province of West Flanders, Belgium, bordering with France. The region comprises a number of hills ("heuvel") on which a fast growing 'wine culture' is developing. Both professional as well as non-professional wine makers together cultivate about 19 ha of vineyards, and are still expanding. Grapes cultivated include Chardonnay, Pinot gris and Pinot noir among others. The small-scale, strongly dispersed vineyards are located in different landscape positions of variable aspect. The objective of our preliminary study was to assess the between-field and within-field variation in physico-chemical soil properties of these vineyards with the aim to better characterise the terroir(s) in Heuvelland and provide guidelines for soil management. Fourteen vineyards from five different wineries were selected for detailed soil sampling. Twenty-five sampling sites were chosen according to the topography, soil map units and observed variability in grape growth. The soil was sampled using 15 cm depth increments up to a depth of 60 cm or a shallower lithic contact. Composite samples of 5 sampling locations along the contour lines were taken per within-field zone. Besides the texture, pH, organic carbon, total nitrogen, available phosphorous and exchangeable base cations (Ca, Mg, K), also some micronutrients (Fe, B, Cu, Mn) were determined using standard laboratory procedures. The soils developed on Quaternary niveo-eolian sandy loam and loamy sediments of variable thickness covering marine sandy and clayey sediments of the Tertiary. Where the Tertiary clayey sediments occur at shallow depth, they can strongly influence the internal drainage. At higher positions in the landscape, iron-rich sandstone layers are found at shallow depth. Fragments of this iron-rich sandstone can also be found at lower positions (colluvial material). This iron sandstone is claimed to contribute to the unique character of this wine

  19. 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

    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...

  20. 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...

  1. A taxonomy of chemicals of emerging concern based on observed fate at water resource recovery facilities.

    Science.gov (United States)

    Jones, Steven M; Chowdhury, Zaid K; Watts, Michael J

    2017-03-01

    As reuse of municipal water resource recovery facility (WRRF) effluent becomes vital to augment diminishing fresh drinking water resources, concern exists that conventional barriers may prove deficient, and the upcycling of chemicals of emerging concern (CECs) could prove harmful to human health and aquatic species if more effective and robust treatment barriers are not in place. A multiple month survey, of both primary and secondary effluents, from three (3) WRRFs, for 95 CECs was conducted in 2014 to classify CECs by their persistence through conventional water reclamation processes. By sampling the participating WRRF process trains at their peak performance (as determined by measured bulk organics and particulates removal), a short-list of recalcitrant CECs that warrant monitoring to assess treatment performance at advanced water reclamation and production facilities. The list of identified CECs for potable water reclamation (indirect or direct potable reuse) include a herbicide and its degradants, prescription pharmaceuticals and antibiotics, a female hormone, an artificial sweetener, and chlorinated flame retardants.

  2. 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

  3. Observed changes of temperature extremes during 1960-2005 in China: natural or human-induced variations?

    Science.gov (United States)

    Zhang, Qiang; Li, Jianfeng; David Chen, Yongqin; Chen, Xiaohong

    2011-12-01

    The purpose of this study was to statistically examine changes of surface air temperature in time and space and to analyze two factors potentially influencing air temperature changes in China, i.e., urbanization and net solar radiation. Trends within the temperature series were detected by using Mann-Kendall trend test technique. The scientific problem this study expected to address was that what could be the role of human activities in the changes of temperature extremes. Other influencing factors such as net solar radiation were also discussed. The results of this study indicated that: (1) increasing temperature was observed mainly in the northeast and northwest China; (2) different behaviors were identified in the changes of maximum and minimum temperature respectively. Maximum temperature seemed to be more influenced by urbanization, which could be due to increasing urban albedo, aerosol, and air pollutions in the urbanized areas. Minimum temperature was subject to influences of variations of net solar radiation; (3) not significant increasing and even decreasing temperature extremes in the Yangtze River basin and the regions south to the Yangtze River basin could be the consequences of higher relative humidity as a result of increasing precipitation; (4) the entire China was dominated by increasing minimum temperature. Thus, we can say that the warming process of China was reflected mainly by increasing minimum temperature. In addition, consistently increasing temperature was found in the upper reaches of the Yellow River basin, the Yangtze River basin, which have the potential to enhance the melting of permafrost in these areas. This may trigger new ecological problems and raise new challenges for the river basin scale water resource management.

  4. Observation and simulation of near-surface wind and its variation with topography in Urumqi, West China

    Science.gov (United States)

    Jin, Lili; Li, Zhenjie; He, Qing; Miao, Qilong; Zhang, Huqiang; Yang, Xinghua

    2016-12-01

    Near-surface wind measurements obtained with five 100-m meteorology towers, 39 regional automatic stations, and simulations by the Weather Research and Forecasting (WRF) model were used to investigate the spatial structure of topography-driven flows in the complex urban terrain of Urumqi, China. The results showed that the wind directions were mainly northerly and southerly within the reach of 100 m above ground in the southern suburbs, urban area, and northern suburbs, which were consistent with the form of the Urumqi gorge. Strong winds were observed in southern suburbs, whereas the winds in the urban, northern suburbs, and northern rural areas were weak. Static wind occurred more frequently in the urban and northern rural areas than in the southern suburbs. In the southern suburbs, wind speed was relatively high throughout the year and did not show significant seasonal variations. The average annual wind speed in this region varied among 1.9-5.5, 1.1-3.6, 1.2-4.3, 1.2-4.3, and 1.1-3.5 m s -1 within the reach of 100 m above ground at Yannanlijiao, Shuitashan, Liyushan, Hongguangshan, and Midong, respectively. The flow characteristics comprised more airflows around the mountain, where the convergence and divergence were dominated by the terrain in eastern and southwestern Urumqi. Further analysis showed that there was a significant mountain-valley wind in spring, summer, and autumn, which occurred more frequently in spring and summer for 10-11 h in urban and northern suburbs. During daytime, there was a northerly valley wind, whereas at night there was a southerly mountain wind. The conversion time from the mountain wind to the valley wind was during 0800-1000 LST (Local Standard Time), while the conversion from the valley wind to the mountain wind was during 1900-2100 LST. The influence of the mountain-valley wind in Urumqi City was most obvious at 850 hPa, according to the WRF model.

  5. Cosmic Origins Spectrograph Observations of the Chemical Composition of LMC N132D

    CERN Document Server

    France, Kevin; Keeney, Brian A; Danforth, Charles W; Froning, Cynthia S; Green, James C

    2009-01-01

    We present new far-ultraviolet spectra of an oxygen-rich knot in the Large Magellanic Cloud supernova remnant N132D, obtained with the Hubble Space Telescope/Cosmic Origins Spectrograph. Moderate resolution (v~200 km/s) spectra in the HST far-ultraviolet bandpass (1150 - 1750 A) show emission from several ionization states of oxygen as well as trace amounts of other species. We use the improvements in sensitivity and resolving power offered by COS to separate contributions from different velocity components within the remnant, as well as emission from different species within the oxygen-rich knot itself. This is the first time that compositional and velocity structure in the ultraviolet emission lines from N132D has been resolved, and we use this to assess the chemical composition of the remnant. No nitrogen is detected in N132D and multiple carbon species are found at velocities inconsistent with the main oxygen component. We find helium and silicon to be associated with the oxygen-rich knot, and use the red...

  6. 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.

  7. 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...

  8. Observation

    Science.gov (United States)

    Patell, Hilla

    2016-01-01

    In order to achieve the goal of observation, preparation of the adult, the observer, is necessary. This preparation, says Hilla Patell, requires us to "have an appreciation of the significance of the child's spontaneous activities and a more thorough understanding of the child's needs." She discusses the growth of both the desire to…

  9. 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

  10. 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

  11. Seasonal and interannual variations in HCN amounts in the upper troposphere and lower stratosphere observed by MIPAS

    Science.gov (United States)

    Glatthor, N.; Höpfner, M.; Stiller, G. P.; von Clarmann, T.; Funke, B.; Lossow, S.; Eckert, E.; Grabowski, U.; Kellmann, S.; Linden, A.; Walker, K. A.; Wiegele, A.

    2015-01-01

    We present a HCN climatology of the years 2002-2012, derived from FTIR limb emission spectra measured with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on the ENVISAT satellite, with the main focus on biomass burning signatures in the upper troposphere and lower stratosphere. HCN is an almost unambiguous tracer of biomass burning with a tropospheric lifetime of 5-6 months and a stratospheric lifetime of about 2 years. The MIPAS climatology is in good agreement with the HCN distribution obtained by the spaceborne ACE-FTS experiment and with airborne in situ measurements performed during the INTEX-B campaign. The HCN amounts observed by MIPAS in the southern tropical and subtropical upper troposphere have an annual cycle peaking in October-November, i.e. 1-2 months after the maximum of southern hemispheric fire emissions. The probable reason for the time shift is the delayed onset of deep convection towards austral summer. Because of overlap of varying biomass burning emissions from South America and southern Africa with sporadically strong contributions from Indonesia, the size and strength of the southern hemispheric plume have considerable interannual variations, with monthly mean maxima at, for example, 14 km between 400 and more than 700 pptv. Within 1-2 months after appearance of the plume, a considerable portion of the enhanced HCN is transported southward to as far as Antarctic latitudes. The fundamental period of HCN variability in the northern upper troposphere is also an annual cycle with varying amplitude, which in the tropics peaks in May after and during the biomass burning seasons in northern tropical Africa and southern Asia, and in the subtropics peaks in July due to trapping of pollutants in the Asian monsoon anticyclone (AMA). However, caused by extensive biomass burning in Indonesia and by northward transport of part of the southern hemispheric plume, northern HCN maxima also occur around October/November in several years

  12. Seasonal and interannual variations of HCN amounts in the upper troposphere and lower stratosphere observed by MIPAS

    Science.gov (United States)

    Glatthor, N.; Höpfner, M.; Stiller, G. P.; von Clarmann, T.; Funke, B.; Lossow, S.; Eckert, E.; Grabowski, U.; Kellmann, S.; Linden, A.; Wiegele, A.

    2014-04-01

    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 tropospheric HCN above the tropical

  13. 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.

  14. 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...

  15. Physical, chemical and biological observations and modeling of oil spills in the Mediterranean Sea

    Science.gov (United States)

    Ribotti, A.; De Dominicis, M.

    2016-11-01

    According to a definition of GESAMP, United Nations advisory body on scientific aspects of marine protection, a marine pollution is: "direct or indirect introduction by man of substances or energy into the marine environment … which results in such deleterious effects as harm to living resources, hazard to human health, hindrance to marine activities including fishing, impairment of water quality and reduction of marine attractions". The works presented in this Special Issue stem from the need to manage the problem of marine pollution. The categories of pollutants associated with the maritime traffic are mainly hydrocarbons and chemicals. Hydrocarbon is the oil in all its forms, including the crude oil, the fuel oil, the sludges, debris and other refined products (as defined by MARPOL 73/78 Annex I (MARPOL, 1978)). An oil spill is a release of a liquid petroleum hydrocarbon into the environment due to human activity, and is a form of pollution. The term often refers to marine oil spills, where oil is released into the open ocean or coastal waters. Oil spills include releases of crude oil from tankers, offshore platforms, drilling rigs and wells, as well as spills of refined petroleum products (such as gasoline, diesel) and their by-products, and heavier fuels used by large ships such as bunker fuel, or the spill of any oily refuse or waste oil. Oil spills can have devastating effects on the marine environment and can jeopardize the functional integrity of the marine ecosystem (seabirds populations, fish communities, and marine mammals), as reported in Jackson et al. (1989), Piatt and Anderson (1996), Peterson et al. (2003). While being toxic to marine life, the hydrocarbons are very difficult to clean up, and last for years in the sediment and marine environment. Discharge of cargo residues from bulk carries can pollute ports, waterways and oceans. In many instances vessels intentionally discharge illegal wastes despite foreign and domestic regulation prohibiting

  16. Assimilating surface observations in a four-dimensional variational Doppler radar data assimilation system to improve the analysis and forecast of a squall line case

    Science.gov (United States)

    Chen, Xingchao; Zhao, Kun; Sun, Juanzhen; Zhou, Bowen; Lee, Wen-Chau

    2016-10-01

    This paper examines how assimilating surface observations can improve the analysis and forecast ability of a fourdimensional Variational Doppler Radar Analysis System (VDRAS). Observed surface temperature and winds are assimilated together with radar radial velocity and reflectivity into a convection-permitting model using the VDRAS four-dimensional variational (4DVAR) data assimilation system. A squall-line case observed during a field campaign is selected to investigate the performance of the technique. A single observation experiment shows that assimilating surface observations can influence the analyzed fields in both the horizontal and vertical directions. The surface-based cold pool, divergence and gust front of the squall line are all strengthened through the assimilation of the single surface observation. Three experiments—assimilating radar data only, assimilating radar data with surface data blended in a mesoscale background, and assimilating both radar and surface observations with a 4DVAR cost function—are conducted to examine the impact of the surface data assimilation. Independent surface and wind profiler observations are used for verification. The result shows that the analysis and forecast are improved when surface observations are assimilated in addition to radar observations. It is also shown that the additional surface data can help improve the analysis and forecast at low levels. Surface and low-level features of the squall line—including the surface warm inflow, cold pool, gust front, and low-level wind—are much closer to the observations after assimilating the surface data in VDRAS.

  17. 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...... ( 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...... 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 sodium and chloride to 75 and 125% for uric acid and AST....

  18. 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

  19. Hydrographic properties in the São Sebastião Channel: daily variations observed in March 1980

    Directory of Open Access Journals (Sweden)

    Belmiro Mendes de Castro

    1998-01-01

    Full Text Available A four-day quasi-synoptic survey of hydrographic properties sampled from March 4 to March 7, 1980 was used for a physical description of the daily variations in the thermohaline and mass structures in the São Sebastião Channel. Temperature and salinity were sampled down the water column during events of non-tidal along channel current reversals. The observed temperature decrease and density increase in the southern channel bottom layer were mainly due to cold water transported northward by a subsurface current. The northward bottom current opposed the southward main flow in the upper layer. The low temperature and salinity of the water advected northward by the bottom current indicated influences of the South Atlantic Central Water (SACW, inducing a near bottom thermocline-like structure. By the end of the sampling period, the vertical temperature gradient intensified near the bottom and the salinity distribution reached almost uniform conditions.Uma amostragem quase sinótica realizada durante quatro dias, no período de 4 a 7 de março de 1980, foi usada para uma descrição de variações das estruturas termohalina e de massa no Canal de São Sebastião. A temperatura e a salinidade foram amostradas na coluna de água durante a reversão do sentido da componente longitudinal da corrente. O decréscimo da temperatura e o aumento da densidade, na entrada sul do canal, foram ocasionados por advecção de águas próximas ao fundo, com sentido oposto ao do . movimento para o sul na camada de superfície. As águas de baixa temperatura, advectadas para o norte, indicam influências da Água Central do Atlântico Sul (ACAS, gerando um gradiente vertical de temperatura nas proximidades do fundo semelhante a uma termoclina. No fim do período do experimento o gradiente vertical de temperatura foi intensificado nas proximidades do fundo e a estrutura halina atingiu condi��ões com f estratificação vertical.

  20. Physical and chemical structure of the IC 63 nebula. 1: Millimeter and far-infrared observations

    Science.gov (United States)

    Jansen, David J.; Van Dishoeck, Ewine F.; Black, John H.

    1994-01-01

    We present results of a (sub)millimeter and far-infrared study of the reflection/emission nebula IC 63, located close to the BO.5p star gamma Cas. The source has been mapped in the (12)CO 2 - 1 and 3 - 2, (13)CO 2 - 1, and CS 2 - 1 lines and shows a small molecular cloud less than 1'x 2' in extent, which coincides with the brightest optical nebulosity and IRAS 100 micrometer emission. IC 63 is therefore an excellent example of a nearby (d approximately = 230 pc), edge-on photon-dominated region (PDR). Various other molecules have been observed at the peak position through their rotational transitions, in order to probe the physical parameters and to derive abundances. The measured CO, HCO(+) HCN, CS and H2CO line ratios suggest that the cloud is warm, T approximately = 50 K, and dense, n (H2) approximately = 5 x 10(exp 4)/cu cm. Excitation of molecules by electrons may play a significant role in this PDR. On the basis of these physical conditions, column densities have been determined from the observed line strengths. Several different methods are discussed to constrain the H2 column density, including the use of measured submillimeter continuum fluxes. The resulting abundances of species such as CN and CS are similar to those found in cold, dark clouds like TMC-1 and L134N. However, the abundances of other simple molecules such as HNC, HCO(+) and possibly C2H are lower by factors of at least three, probably because of the enhanced photodissociation rates at a distance of 1.3 pc from a B star. Surprisingly, only the abundance of the H2S molecule appears enhanced. More complex, volatile molecules such as CH3OH CH3CN and HNCO, and the sulfur-oxides SO and SO2 have not been found in this cloud. Limited observations of molecules in the reflection nebulea NGC 2023 are presented as well, and the resulting molecular abundances are compared with those found for IC 63.

  1. The Physical Structure and Chemical Composition of Neptune's Atmosphere from Combined Herschel and Spitzer Spectral Observations

    Science.gov (United States)

    Orton, Glenn S.; Moreno, R.; Lellouch, E.; Fletcher, L. N.; Hartogh, P.; Feuchtgruber, H.; Jarchow, C.; Cavalie, T.; Lara, L.; Rengel, M.; Gonzalez, A.; Line, M.; Herschel HssO Key Project Team

    2010-10-01

    We report the analysis of thermal-infrared observations of Neptune's disk by experiments on the Spitzer and Herschel Space Telescopes. The Spitzer data were obtained by the IRS instrument at wavelengths between 5.2 and 21.5 microns at a spectral resolving power, R 70, and at wavelengths between 10 and 21.5 microns at R 600. The Herschel observations were made by the PACS instrument's integral field spectrometer between 51 and 220 microns at R 3000, within the framework of the Key Project, ``Water and Related Chemistry in the Solar System''. Our analysis is set in the context of lower-resolution spectra obtained by the ISO LWS and SWS spectrometers covering wavelengths between 28 and 185 microns and the Akari IRC spectrometer covering wavelengths between 5.8 and 13.3 microns at R 40, together with spatially resolved ground-based studies of thermal emission. Our results indicate that that global-mean tropospheric temperatures are lower than those derived from the Voyager radio-occultation experiment, and consistent with the ISO results. Preliminary results (Lellouch et al. 2010 Astron. & Astrophys. In press) indicate that the D/H ratio is 4.5±1.0 x 10-5, consistent with enrichment of deuterium over the protosolar value, and the stratospheric column of H2O is 2.1±0.5 x 1014 cm-2. The peak CH4 abundance in the stratosphere is orders of magnitude larger than if it were cold-trapped below the mean 54-Kelvin tropopause minimum temperature - but consistent with injection from Neptune's warmer south polar region. Good fits to a variety of other stratospheric emission features are obtained: CO, CH3, CO2, C2H2, C2H4, C2H6, C3H8, C4H2. It is also possible to obtain a better fit to a spectral region dominated by C2H6 emission by adding 50-100 ppt of C6H6.

  2. Complex, dynamic combination of physical, chemical and nutritional variables controls spatio-temporal variation of sandy beach community structure.

    Science.gov (United States)

    Ortega Cisneros, Kelly; Smit, Albertus J; Laudien, Jürgen; Schoeman, David S

    2011-01-01

    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-exposed sandy

  3. Chemical evolution in Sersic 159-03 observed with XMM-Newton

    CERN Document Server

    De Plaa, J; Bonamente, M; Bykov, A M; Kaastra, J S; Méndez, M; Peterson, J R; Vink, J; Werner, N

    2006-01-01

    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 ch...

  4. Spatial variation in foliar chemicals within radish (Raphanus sativus) plants and their effects on performance of Spodoptera litura.

    Science.gov (United States)

    Yadav, Jitendra; Tan, Ching-Wen; Hwang, Shaw-Yhi

    2010-12-01

    Foliar chemicals are variable within a plant and this may affect herbivore feeding preference. This study was carried out to quantify concentrations of primary (nitrogen, water, and total nonstructural carbohydrates) and secondary substances (sinigrin) in young and old leaves of Raphanus sativus L. and to evaluate performance and survival of a generalist herbivore Spodoptera litura F. feeding on them. Forty to 50-d-old R. sativus plants were used in both foliar chemical analysis and insect performance bioassays. Leaves located on the third to the sixth node from the base of the plant were defined as old leaves and the remaining leaves (from seventh node to the plant apex) of the plant were referred as young leaves in this study. All foliar chemicals except water differed significantly between young and old leaves. Moreover, young leaves were more nutritious but much more defended, based on sinigrin content, against S. litura than old leaves. Performance and survival of S. litura were reduced on young leaves as compared with old leaves. Male and female larval duration only differed significantly on young leaves. Female larval development time was longer than male development time on young leaves, but not on older leaves. Therefore, this study revealed that defenses in young leaves have differential effects upon male and female S. litura.

  5. Temporal variation of chemical and mechanical weathering in NE Iceland: Evaluation of a steady-state model of erosion

    Science.gov (United States)

    Eiriksdottir, E. S.; Louvat, P.; Gislason, S. R.; Óskarsson, N.; Hardardóttir, J.

    2008-07-01

    This study critically assesses the temporal sensitivity of the steady-state model of erosion that has been applied to chemical and mechanical weathering studies of volcanic islands and the continents, using only one sample from each catchment. The model assumes a geochemical mass balance between the initially unweathered rock of a drainage basin and the dissolved and solid loads of the river. Chemical composition of 178 samples of suspended and dissolved inorganic river constituents, collected in 1998-2002, were studied from five basaltic river catchments in NE Iceland. The Hydrological Service in Iceland has monitored the discharge and the total suspended inorganic matter concentration (SIM) of the glacial rivers for ~ four decades, making it possible to compare modelled and measured SIM fluxes. Concentration of SIM and grain size increased with discharge. As proportion of clay size particles in the SIM samples increased, concentrations of insoluble elements increased and of soluble decreased. The highest proportion of altered basaltic glass was in the clay size particles. The concentration ratio of insoluble elements in the SIM was used along with data on chemical composition of unweathered rocks (high-Mg basalts, tholeiites, rhyolites) to calculate the pristine composition of the original catchment rocks. The calculated rhyolite proportions compare nicely with area-weighted average proportions, from geological maps of these catchments. The calculated composition of the unweathered bedrock was used in the steady-state model, together with the chemical composition of the suspended and dissolved constituents of the river. Seasonal changes in dissolved constituent concentrations resulted in too low modelled concentrations of SIM mod at high discharge (and too high SIM mod at low discharge). Samples collected at annual average river dissolved load yielded SIM mod concentrations close to the measured ones. According to the model, the studied rivers had specific

  6. Summertime Spatial Variations in Atmospheric Particulate Matter and Its Chemical Components in Different Functional Areas of Xiamen, China

    Directory of Open Access Journals (Sweden)

    Shuhui Zhao

    2015-02-01

    Full Text Available Due to the highly heterogeneous and dynamic nature of urban areas in Chinese cities, air pollution exhibits well-defined spatial variations. Rapid urbanization in China has heightened the importance of understanding and characterizing atmospheric particulate matter (PM concentrations and their spatiotemporal variations. To investigate the small-scale spatial variations in PM in Xiamen, total suspended particulate (TSP, PM10, PM5 and PM2.5 measurements were collected between August and September in 2012. Their average mass concentrations were 102.50 μg∙m−3, 82.79 μg∙m−3, 55.67 μg∙m−3 and 43.70 μg∙m−3, respectively. Organic carbon (OC and elemental carbon (EC in PM2.5 were measured using thermal optical transmission. Based on the PM concentrations for all size categories, the following order for the different functional areas studied was identified: hospital > park > commercial area > residential area > industrial area. OC contributed approximately 5%–23% to the PM2.5 mass, whereas EC accounted for 0.8%–6.95%. Secondary organic carbon constituted most of the carbonaceous particles found in the park, commercial, industrial and residential areas, with the exception of hospitals. The high PM and EC concentrations in hospitals were primarily caused by vehicle emissions. Thus, the results suggest that long-term plans should be to limit the number of vehicles entering hospital campuses, construct large-capacity underground parking structures, and choose hospital locations far from major roads.

  7. 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

  8. 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.

  9. Seasonal and inter-annual variations of length of day and polar motion observed by SLR in 1993-2006

    Institute of Scientific and Technical Information of China (English)

    GUO JinYun; HAN YanBen

    2009-01-01

    A time series of length of the day (LOD) and polar motion (PM) were estimated from the range data measured by the satellite laser ranging technique (SLR) to LAGEOS 1/2 through 1993 to 2006.Com-pared with EOPC04 released by the International Earth Rotation and Reference Systems Service (IERS),the root mean squares errors for LOD,X and Y of PM are 0.0067 milliseconds (ms),0.18 milli-arc-sec-onds (mas) and 0.20 mas,respectively.Then the time series are analyzed with the wavelet transforma-tion and least squares method.Wavelet analysis shows that there are the obvious seasonal and inter-annual variations of LOD and PM,but the annual variation cannot be distinguished from the Chandler variation because these two frequencies are very close.The trends and periodic variations of LOD and PM are given in the least squares sense.LOD changes with the annual and semiannual periods.The annual and Chandler variations for PM are also detected,but the semiannual motion for PM is not found.The trend rate of the LOD change in 1993-2006 is -0.18 ms per year,and the difference from the well-known 1.7 ms per century showed that the trend rate is diverse in different periods possibly.The trend rates of PM in the X and Y directions are 2.25 and 1.67 mas per year respectively,and the North Pole moves to 36.5°E relative to the crust,which is different from the direction of Greenland.

  10. 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.

  11. OH observations in a tropical rain forest environment using a chemical ionization mass spectrometry technique during GOAmazon intensive campaigns

    Science.gov (United States)

    Kim, S.; Seco, R.; Park, J. H.; Sjostedt, S. J.; Guenther, A. B.; Smith, J. N.; Liu, Y.; Bustillos, J. O. V.; Souza, R. A. F. D.; Tota, J.; Martin, S. T.

    2015-12-01

    We will present observed OH in the Amazon rain forest using a chemical ionization mass spectrometer (CIMS). The observation was conducted at the T3 site in Manacapuru, Amazonas Brazil. It had been accepted almost as an axiom that very low OH is expected in low NO environments such as a pristine rain forest. However, recent studies in the pristine rain forest environments consistently reported significantly higher than expected OH levels. This sparked extensive and intensive studies to explore any possibility of OH regeneration from isoprene photo-oxidation processes in the low NO condition. Four OH regeneration processes related with isoprene photochemistry have been proposed since 2008. However, the levels of the expected OH enhancement vary greatly among the proposed OH regeneration processes mediated by the isoprene oxidation processes. As all enhanced OH observations from the pristine areas with high isoprene conditions have used the laser induced fluorescence (LIF) technique, the possibilities of potential positive artifacts have also been explored. In this context, the first tropical forest CIMS OH dataset will be discussed in the context of 1) comparisons with previously reported OH using the LIF technique, 2) comparisons with box model calculated OH with different isoprene oxidation scenarios to reconcile measured and calculated OH, and 3) comparisons with regional model calculated OH. The CIMS observational dataset along with a comprehensive trace gas dataset provides a constraint to assess current uncertainty in oxidation capacity of the pristine forested region, which has tremendous implications towards global fates of short lived climate forcers.

  12. 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…

  13. 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.

  14. 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.

  15. 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.

  16. Hygroscopicity and chemical composition of Antarctic sub-micrometre aerosol particles and observations of new particle formation

    Directory of Open Access Journals (Sweden)

    E. Asmi

    2009-12-01

    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.

  17. 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.

  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

    2016-03-02

    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.

  19. Variation in nutritional quality and chemical composition of fresh strawberry fruit: combined effect of cultivar and storage.

    Science.gov (United States)

    Dragišić Maksimović, Jelena; Poledica, Milena; Mutavdžić, Dragosav; Mojović, Miloš; Radivojević, Dragan; Milivojević, Jasminka

    2015-03-01

    Bioclimatic air ionisation system (BI) works by neutralising air pollutants and microorganisms by means of oxidation with "activated oxygen". We investigated the effects of storage on changes in weight loss, chemical and sensory fruit properties in eight cultivars of strawberries (Fragaria x ananassa Duch.). All cultivars were evaluated for their standard parameters of quality (soluble solids content, total acidity, vitamin C content, total antioxidant activity - TAC, total phenolic and anthocyanins content) at different store conditions: fresh fruits-control, cold stored (at 4 °C) fruits without controlled atmospheres and cold stored (at 4 °C) fruits in BI. The present study outlines that anthocyanins of the strawberries stored in BI were subjected to significant degradation. These strawberries have prolonged shelf-life accompanied by weight loss reduction, TAC increment, and sensory properties improvement in tested cultivars, retaining other nutritional fruit qualities.

  20. Seasonal variation and partitioning of endocrine disrupting chemicals in waters and sediments of the Pearl River system, South China.

    Science.gov (United States)

    Gong, Jian; Duan, Dandan; Yang, Yu; Ran, Yong; Chen, Diyun

    2016-12-01

    Endocrine disrupting chemicals (EDCs) were seasonally investigated in surface water, suspended particulate matter, and sediments of the Pearl River Delta (PRD), South China. EDC concentrations in the surface water were generally higher in the summer than in winter. The surface water in the investigated rivers was heavily contaminated by the phenolic xenoestrogens. Moreover, the in-situ log Ksoc and log Kpoc values and their regression with log Kow in the field experiments suggest that binding mechanisms other than hydrophobic interaction are present for the sedimentary organic carbon and particulate organic carbon (SOC/POC). The logKsoc-logKow and logKpoc-logKow regression analyses imply that higher complexity of nonhydrophobic interactions with EDCs is present on the SOC samples comparing with the POC samples, which is related to their different sources.

  1. Seasonal variation in the chemical composition, antioxidant activity, and total phenolic content of Artemisia absinthium essential oils

    Directory of Open Access Journals (Sweden)

    A Mohammadi

    2015-01-01

    Full Text Available Background: The genus Artemisia belonging to the Compositae (Asteraceae family and many traditional uses from the Artemisia species were reported. Artemisia absinthium is one of the species in this genus and commonly used in the food industry in the preparation of aperitifs, bitters, and spirits. Objective: Evaluation of the effect of different harvesting stages on the composition of essential oil and antioxidant capacity of A. absinthium. Materials and Methods: Essential oils from the aerial parts of A. absinthium, collected in three stages (preflowering, flowering, and after-flowering from plants grown in the North Khorasan province of Iran were obtained by steam distillation and the chemical composition of the oils was analyzed by gas chromatography-mass spectrometry and antioxidant activity and total phenolic content were determined by 2-diphenyl-1-picrylhydrazyl assay and Folin-Ciocalteu method. Results: Analysis of the isolated oils revealed the presence of 44 compounds, mainly alpha-pinene, sabinene, beta-pinene, alpha-phellandrene, p-cymene and chamazulene. Alpha-phellandrene, and chamazulene were major compounds in preflowering stage, but beta-pinene and alpha-phellandrene were major in flowering and past-flowering stages. Flowering stage had highest yield and after flowering stage had lowest yield. The essential oil of preflowering stage had the highest amount of antioxidant compound (chamazulene. Preflowering stage with highest amount of phenolic compounds had the strongest antioxidant activity with the lowest amount of EC 50 . Conclusion: This study showed that the harvesting stage had significant effects on chemical composition and antioxidant properties of essential oils, and chamazulene is main compound for antioxidant activity in A. absinthium.

  2. Variations of biomarkers response in mussels Mytilus galloprovincialis to low, moderate and high concentrations of organic chemicals and metals.

    Science.gov (United States)

    Perić, Lorena; Nerlović, Vedrana; Žurga, Paula; Žilić, Luka; Ramšak, Andreja

    2017-05-01

    The changes of acetylcholinesterase activity (AChE), metallothioneins content (MTs), catalase activity (CAT) and lipid peroxidation (LPO) were assessed after 4 days exposure of mussels Mytilus galloprovincialis to a wide range of sublethal concentrations of chlorpyrifos (CHP, 0.03-100 μg/L), benzo(a)pyrene (B(a)P, 0.01-100 μg/L), cadmium (Cd, 0.2-200 μg/L) and copper (Cu, 0.2-100 μg/L). The activity of AChE in the gills decreased after exposure to CHP and Cu, whereas no change of activity was detected after exposure to B(a)P and Cd. Both induction and decrease of MTs content in digestive gland occurred after exposure to CHP and B(a)P, while a marked increase was evident at highest exposure concentrations of Cd. The content of MTs progressively decreased of MTs with increasing concentration of Cu. CAT activity and LPO in the gills did not change after exposure to any of the chemicals. The results demonstrate different response profile in relation to the type of chemical compound, and highlight the potential implications for evaluation of biological effect of contaminants in marine environment. Furthermore, the AChE activity in the gills and MTs content in the digestive gland could be modulated by CHP and Cu at environmentally relevant concentrations indicating the potential risks of short-term transient mussels exposure that may occur due to run-off from land or accidental releases.

  3. 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

    2014-07-15

    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.

  4. 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.

  5. 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.

  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

    2012-08-01

    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.

  7. Alteration of Fractured Rocks Due to Coupled Chemical and Mechanical Processes: High-Resolution Simulations and Experimental Observations

    Science.gov (United States)

    Ameli, Pasha

    Engineering activities such as enhanced geothermal energy production and improved oil recovery techniques are heavily dependent on the permeability of the subsurface, while others such as CO2 sequestration and nuclear waste disposal rely on the efficiency of rock formations as transport barriers. In either case fractures provide the main pathways for fluid flow and transport, especially in rocks with lower matrix porosity. Laboratory experiments aimed at quantifying the chemo-mechanical responses of fractures have shown a range of results, some of which contradict simple conceptual models. For example, under conditions favoring mineral dissolution, where one would expect an overall increase in permeability, experiments show that permeability increases under some conditions and decreases under others. Recent experiments have attempted to link these core-scale observations to the relevant small-scale processes occurring within fractures. Results suggest that the loss of mechanical strength in asperities due to chemical alteration may cause non-uniform deformation and alteration of fracture apertures. However, due to the lack of direct micro-scale measurements of the coupled chemical and mechanical processes that lead to alteration of contacting fracture surfaces, our ability to predict the long-term evolution of fractures is still limited. To explore the processes that control permeability evolution, I developed a computational model that uses micro-scale surface roughness and explicitly couples dissolution and elastic deformation to calculate local alterations in fracture aperture under chemical and mechanical stresses. A depth-averaged algorithm of fracture flow is used to model reactive transport and chemical alteration of the fracture surfaces. Then, I deform the resulting altered fracture-surfaces using an algorithm that calculates the elastic deformation. The results of the model are compared with flow-through experiments conducted on fractured limestone. The

  8. Relativistic electron microbursts and variations in trapped MeV electron fluxes during the 8-9 October 2012 storm: SAMPEX and Van Allen Probes observations

    Science.gov (United States)

    Kurita, Satoshi; Miyoshi, Yoshizumi; Blake, J. Bernard; Reeves, Geoffery D.; Kletzing, Craig A.

    2016-04-01

    It has been suggested that whistler mode chorus is responsible for both acceleration of MeV electrons and relativistic electron microbursts through resonant wave-particle interactions. Relativistic electron microbursts have been considered as an important loss mechanism of radiation belt electrons. Here we report on the observations of relativistic electron microbursts and flux variations of trapped MeV electrons during the 8-9 October 2012 storm, using the SAMPEX and Van Allen Probes satellites. Observations by the satellites show that relativistic electron microbursts correlate well with the rapid enhancement of trapped MeV electron fluxes by chorus wave-particle interactions, indicating that acceleration by chorus is much more efficient than losses by microbursts during the storm. It is also revealed that the strong chorus wave activity without relativistic electron microbursts does not lead to significant flux variations of relativistic electrons. Thus, effective acceleration of relativistic electrons is caused by chorus that can cause relativistic electron microbursts.

  9. 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

    2016-12-01

    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.

  10. Variation in some chemical parameters and organic matter in soils regenerated by the addition of municipal solid waste

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, C.; Hernandez, T.; Costa, F. (Centro de Edafologia y Biologia, Murcia (Spain))

    The organic fraction of a municipal solid waste was added in different doses to an eroded soil formed of loam and with no vegetal cover. After three years, the changes in macronutrient content and the chemical-structural composition of its organic matter were studied. The addition of the organic fraction from a municipal solid waste had a positive effect on soil regeneration, the treated soils being covered with spontaneous vegetation from 1 yr onwards. An increase in electrical conductivity and a fall in pH were noted in the treated soils as were increases in macronutrients, particularly N and available P and the different carbon fractions. Optical density measurements of the organic matter extracted with sodium pyrophosphate showed that the treated soils contained an organic matter with less condensed compounds and with a greater tendency to evolve than the control. A pyrolysis-gas chromatography study of the organic matter extracted with pyrophosphate showed large quantities of benzene both in the treated soils and control; pyrrole was also relatively abundant, although this fragment decreased as the dose rose. Xylenes and pyridine were present in greater quantities in the control and furfural in the treated soils.

  11. Spatial Variations of the Synchrotron Spectrum Within Tycho’s Supernova Remnant (3C 10): A Spectral Tomography Analysis of Radio Observations at 20 and 90 Centimeter Wavelengths

    Science.gov (United States)

    2000-01-20

    individual ( Tycho ) 1. INTRODUCTION A new star observed by Tycho Brahe (1573) is now identi- Ðed as a supernova whose remnant (SNR) is 3C 10 (SN 1572... Tycho SNR, SNR 120.1]1.4 ; Lozinskaya 1992 and references therein). The explosion itself was mostly likely a Type Ia supernova, and the remnant seems...we adopted.3 Again, this procedure tends to reduce any spectral variations. However, as Reynoso et al. (1997) found, Tycho is not expanding

  12. 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...

  13. Observed and calculated 1H and 13C chemical shifts induced by the in situ oxidation of model sulfides to sulfoxides and sulfones.

    Science.gov (United States)

    Dracínský, Martin; Pohl, Radek; Slavetínská, Lenka; Budesínský, Milos

    2010-09-01

    A series of model sulfides was oxidized in the NMR sample tube to sulfoxides and sulfones by the stepwise addition of meta-chloroperbenzoic acid in deuterochloroform. Various methods of quantum chemical calculations have been tested to reproduce the observed (1)H and (13)C chemical shifts of the starting sulfides and their oxidation products. It has been shown that the determination of the energy-minimized conformation is a very important condition for obtaining realistic data in the subsequent calculation of the NMR chemical shifts. The correlation between calculated and observed chemical shifts is very good for carbon atoms (even for the 'cheap' DFT B3LYP/6-31G* method) and somewhat less satisfactory for hydrogen atoms. The calculated chemical shifts induced by oxidation (the Delta delta values) agree even better with the experimental values and can also be used to determine the oxidation state of the sulfur atom (-S-, -SO-, -SO(2)-).

  14. A comparison of f{sub 0}E and hmE model calculations with El Arenosillo digisonde observations. Seasonal variations

    Energy Technology Data Exchange (ETDEWEB)

    Mikhailov, A. [Institute of Terrestial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, Troitsk, Moscow Region (Russian Federation); La Morena de, B.A.; Miro, G.; Marin, D. [National Institute of Aerospace Technology, Mazagon, Huelva (Spain)

    1999-08-01

    Seasonal variation of hmE and f{sub 0}F{sub 2} are analyzed using El Arenosillo digisonde observations during solar minimum (1995-1996). Unlike some widely used empirical models daytime hmE show seasonal variations with winter hmE being higher than summer ones and seasonal differences increase with solar zenith angle. Model calculations enable to reproduce the observed hmE seasonal variations but the calculate daytime f{sub 0}F{sub 2} values are too low if conventional EUV fluxes and dissociative recombination rate constants are used. A reduction of {alpha}(NO{sup +}) by taking into T{sub e}>T{sub n} in the E-region as it follows from probe measurements seems to be a plausible solution. The E-region ion composition corresponding to rocket observations may be obtained in model calculations using an appropriate (NO) height distribution. Calculate summer concentrations of (NO) are by a factor of 3-4 larger than winter ones at the hmE-heights.

  15. Preliminary observations and simulation of nocturnal variations of airglow temperature and emission rates at Pune (18.5°N), India

    Science.gov (United States)

    Fadnavis, S.; Feng, W.; Shepherd, Gordon G.; Plane, J. M. C.; Sonbawne, S.; Roy, Chaitri; Dhomse, S.; Ghude, S. D.

    2016-11-01

    Preliminary observations of the nocturnal variations of the OH(6-2) and O2b(0-1) nighttime airglow in the mesosphere and lower thermosphere are investigated in the context of tidal influence for the tropical latitude station Pune (18.5°N, 73.85°E). This is the only tropical Spectral Airglow Temperature Imager (SATI) station where the tidal variations of mesosphere and lower thermosphere (MLT) temperature have been determined from ground based SATI observations. The SATI observations obtained since October 2012 reveal the influence of the migrating semidiurnal tides during solstice at this tropical station. There is variability in amplitude and phase obtained from SATI observations. In this paper, SATI observations on 10 Dec 2012 and 3 March 2013 are compared with Whole Atmosphere Community Climate Model (WACCM) simulations. The amplitude of semidiurnal tides is ~25 K/30 K on 10 Dec 2012 during solstice for OH/O2 temperature. During equinox SATI data indicates existence of semidiurnal tide also. The airglow observations are compared with simulations from the WACCM. The model underestimates the amplitude of the semi diurnal tide during equinox (1.6 K/2.7 K at 87 km/96 km) and solstice (~3.8 K/4.8 K at 87 km/96 km) for these days. The reason may be related to dampening of tides in the model due to the effect of strong latitudinal shear in zonal wind. The diurnal variation of airglow emission - which the model simulates well - is related to the vertical advection associated with the tides and downward mixing of atomic oxygen.

  16. 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

  17. 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

  18. 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...... elements as observed on photographic images of cortical bone, in order to assess intra- and inter-observer error. Overall, substantial error was present at the level of identifying and counting secondary osteons, osteon fragments and Haversian canals. Only secondary osteons can be reliably identified...

  19. Seasonal Variation in the Chemical Composition and Antimicrobial Activity of Volatile Oils of Three Species of Leptospermum (Myrtaceae Grown in Brazil

    Directory of Open Access Journals (Sweden)

    Antonio Lelis Pinheiro

    2011-01-01

    Full Text Available This study investigates the seasonal variation of three species of Leptospermum (Myrtaceae grown in Brazil. The chemical composition of the volatile oils of L. flavescens and L. petersonii did not show any significant seasonal variation in the major components, while for Leptospermum madidum subsp. sativum the levels of major constituents of the volatile oils varied with the harvest season. Major fluctuations in the composition of L. madidum subsp. sativum oil included α-pinene (0–15.2%, β-pinene (0.3–18.5%, α-humulene (0.8–30%, 1,8-cineole (0.4–7.1% and E-caryophyllene (0.4–11.9%. Levels of β-pinene (0.3–5.6%, terpinen-4-ol (4.7–7.2% and nerolidol (55.1–67.6% fluctuated seasonally in the L. flavescens oil. In L. petersonii, changes were noted for geranial (29.8–32.8%, citronellal (26.5–33.9% and neral (22.7–23.5%. The activity of the volatile oils against the tested bacteria differed, depending on season the oils were obtained. In general, the volatile oils were more active against Gram-positive bacteria.

  20. Fusing Mobile In Situ Observations and Satellite Remote Sensing of Chemical Release Emissions to Improve Disaster Response

    Directory of Open Access Journals (Sweden)

    Ira Leifer

    2016-09-01

    Full Text Available Chemical release disasters have serious consequences, disrupting ecosystems, society, and causing significant loss of life. Mitigating the destructive impacts relies on identification and mapping, monitoring, and trajectory forecasting. Improvements in sensor capabilities are enabling airborne and spacebased remote sensing to support response activities. Key applications are improving transport models in complex terrain and improved disaster response.Chemical release disasters have serious consequences, disrupting ecosystems, society, and causing significant loss of life. Mitigating the destructive impacts relies on identification and mapping, monitoring, and trajectory forecasting. Improvements in sensor capabilities are enabling airborne and space-based remote sensing to support response activities. Key applications are improving transport models in complex terrain and improved disaster response.Understanding urban atmospheric transport in the Los Angeles Basin, where topographic influences on transport patterns are significant, was improved by leveraging the Aliso Canyon leak as an atmospheric tracer. Plume characterization data was collected by the AutoMObile trace Gas (AMOG Surveyor, a commuter car modified for science. Mobile surface in situ CH4 and winds were measured by AMOG Surveyor under Santa Ana conditions to estimate an emission rate of 365±30% Gg yr-1. Vertical profiles were collected by AMOG Surveyor by leveraging local topography for vertical profiling to identify the planetary boundary layer at ~700 m. Topography significantly constrained plume dispersion by up to a factor of two. The observed plume trajectory was used to validate satellite aerosol optical depth-inferred atmospheric transport, which suggested the plume first was driven offshore, but then veered back towards land. Numerical long-range transport model predictions confirm this interpretation. This study demonstrated a novel application of satellite aerosol remote

  1. Variation of the chemical profile and antioxidant behavior of Rosmarinus officinalis L. and Salvia fruticosa Miller grown in Greece.

    Science.gov (United States)

    Papageorgiou, Vassiliki; Gardeli, Chryssavgi; Mallouchos, Athanasios; Papaioannou, Marina; Komaitis, Michael

    2008-08-27

    In this study, the essential oil and the phenolic composition along with the antioxidant activity of R. officinalis L. and S. fruticosa Miller, collected in Zakynthos island (Ionian Sea, Greece), were investigated. The essential oil composition of the plants was characterized by the presence of 1,8-cineole. Mean values of the antioxidant activities of rosemary and sage essential oils indicated slight differences. The antioxidant activity of sage oil was correlated with the oxygenated sesquiterpenes and diterpenes concentrations. Concerning the methanolic extracts, a close relationship between the phenolic content and the development stage during vegetative cycle of these plants was observed. The identified flavonoids, except rutin, seemed to increase with the advancement of developmental stages, while phenolic acids followed an opposite pattern. The antioxidant activity was correlated with the amount of total phenolic content.

  2. Seasonal and Non-Seasonal Variations of Jupiter's Atmosphere from Observations of Thermal Emission, 1994-2011

    Science.gov (United States)

    Orton, G.; Fletcher, L.; Yanamandra-Fisher, P.; Greathouse, T.; Fisher, B.; Greco, J.; Wakefield, L.; Snead, E.; Boydstun, K.; Simon-Miller, A.; Arzumanyan, G.; Christian, J.

    2012-01-01

    We analyzed mid-infrared images of Jupiter's thermal emission, covering approx.1.5 Jovian years, acquired in discrete filters between 7.8 and 24.5 microns. The behavior of stratospheric (approx.10-mbar) and tropospheric (approx.100-400 mbar) temperatures is generally consistent with predictions of seasonal variability, with differences between 100-mbar temperatures +/-50-60deg from the equator on the order of +/-2. Removing this effect, there appear to be long-term quasi-periodic variability of tropospheric temperatures, whose amplitude, phase and period depend on latitude. The behavior of temperatures in the Equatorial Zone (EZ) suggests a approx.4-6-year period with amplitude of about +/-1-1.5 K in temperature. At mid-latitudes, the periodicity is more distinct with amplitudes around +/-1.5-2.5 K and 4-8 year periods. The 4.2-year variation of stratospheric temperatures known as the quasiquadrennial oscillation or "QQO" (Leovy et al. 1991, Nature 354, 380) continued during this period. There were no variations of zonal mean temperatures associated with any of the "global upheaval" events that have produced dramatic changes of jupiter's visible appearance and cloud cover, although there are colder discrete regions associated with updrafts, e.g. the early stages of the re-darkening ("revival") of the South Equatorial Belt (SEB) in late 2010. On the other hand increases in the visible albedos ("fades") of belts are accompanied by increases in the thickness of a 700-mbar cloud layer (most likely NH3 ice) and clouds at higher pressures, together with the mixing ratio of NH3 gas near 400 mbar (above its condensation level). These quantities decrease during re-darkening ("revival") episodes, during which we note discrete features that are exceptions to the general correlation between dark albedos and minimal cloudiness. In contrast to all these changes, the meridional distribution of the 240-mbar para-H2 fraction appears to be invariant in time.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. Two-Dimensional Variational Analysis of Near-Surface Moisture from Simulated Radar Refractivity-Related Phase Change Observations

    Institute of Scientific and Technical Information of China (English)

    Ken-ichi SHIMOSE; Ming XUE; Robert D.PALMER; Jidong GAO; Boon Leng CHEONG; David J.BODINE

    2013-01-01

    Because they are most sensitive to atmospheric moisture content,radar refractivity observations can provide high-resolution information about the highly variable low-level moisture field.In this study,simulated radar refractivity-related phase-change data were created using a radar simulator from realistic high-resolution model simulation data for a dryline case.These data were analyzed using the 2DVAR system developed specifically for the phase-change data.Two sets of experiments with the simulated observations were performed,one assuming a uniform target spacing of 250 m and one assuming nonuniform spacing between 250 m to 4 km.Several sources of observation error were considered,and their impacts were examined.They included errors due to ground target position uncertainty,typical random errors associated with radar measurements,and gross error due to phase wrapping.Without any additional information,the 2DVAR system was incapable of dealing with phase-wrapped data directly.When there was no phase wrapping in the data,the 2DVAR produced excellent analyses,even in the presence of both position uncertainty and random radar measurement errors.When a separate pre-processing step was applied to unwrap the phase-wrapped data,quality moisture analyses were again obtained,although the analyses were smoother due to the reduced effective resolution of the observations by interpolation and smoothing involved in the unwrapping procedure.The unwrapping procedure was effective even when significant differences existed between the analyzed state and the state at a reference time.The results affirm the promise of using radar refractivity phase-change measurements for near-surface moisture analysis.

  11. Seasonal variations and sources of mass and chemical composition for PM10 aerosol in Hangzhou,China

    Institute of Scientific and Technical Information of China (English)

    Junji Cao; Zhenxing Shen; Judith C.Chow; Guowei Qi; John G.Watsonc

    2009-01-01

    Aerosol observation was conducted for four seasons from September 2001 to August 2002 at five sampling sites in Hangzhou, South China, on PM10 mass, 22 elements (Na, Mg, Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Cd, Ba, and Pb), 5 major ions (F-, Cl-, NO3-, SO42-, and NH4+), and organic and elemental carbon (OC and EC), showing that PM10 mass ranged from 46.7 to 270.8 μg/m3, with an annual average of 119.2 μg/m3. Na, AI, Si, S. K, Ca, and Fe were the most abundant elements in PM10, most ors being in the form of SO42-. SO42-, NO4-, and NH4+ were the major ions, which contributed to about 20%; of the PM10 mass. The mean seasonal concentrations for SO42- , averaged over all sites, were found to be 18.0, 18.5, 24.Z and 21.4 μg/m3. for spring, summer, autumn, and winter, respectively, while the corresponding Ioadings for NO3- were 72, 4.7, 7.1, and 11.2μg/m3. and for NH4+ were 6.0, 5.9, 8.2. and 9.3 μg/m3, in the form mostly of NH4NO3 in spring, autumn, and winter, and mostly of (NH4)2SO4 in summer. The low NO3-/SO42- ratio found indicates coal combustion as the major source throughout the year. The mean annual concentrations of OC and EC in PM10 were found to be 21A, and 4.1 μg/m3, respectively. Material balance calculation indicated that fugitive dust, the secondary aerosol, and carbonaceous matter were the most abundant species in PM10 for the four seasons, as is characteristic for cities in South China.

  12. The effect of chemical variations on the structural polarity of relaxor ferroelectrics studied by resonance Raman spectroscopy.

    Science.gov (United States)

    Rohrbeck, A; de la Flor, G; Aroyo, M I; Gospodinov, M; Bismayer, U; Mihailova, B

    2016-11-30

    Resonance Raman spectroscopy was applied to doped PbSc0.5Ta0.5O3 and PbSc0.5Nb0.5O3 relaxor ferroelectrics, to better understand the effect of composition disorder on the mesoscopic-scale polar order in complex perovskite-type (ABO3) ferroelectrics. The excitation photon energy used was 3.8 eV, which is slightly above the energy gap and corresponds to the maximum of the optical dielectric permittivity. Group-theory analysis reveals that the resonance Raman scattering (RRS) observed under these conditions is allowed only in polar crystal classes. Therefore, RRS is dominated by the atomic dynamics of nanoregions with coherent polar distortions, which considerably facilitates the comparison of polar order in various compounds. The results show that A-site doping (Ba(2+), Sr(2+), La(3+), Bi(3+)) has significantly stronger effect on the structural polarity than the introduction of a third element at the B site (Nb(5+) or Sn(4+) doped in PbSc0.5Ta0.5O3). The A-site substitution by cations that in contrast to Pb(2+) have isotropic outermost electron shells disturbs the system of lone-pair electrons, thus reducing the correlation length of coupled polar distortions and the strength of the electric field associated with the mean polarization of polar nanoregions. A-site doping with larger cations (Ba(2+)) augments the polar deformation of the individual BO6 octahedra due to local elastic fields. As a result, such A-site doping intensifies the initial structural polarity at high temperatures and prevails the enlargement of the polar fraction at low temperatures. A-site doping with smaller cations (Sr(2+), La(3+)), regardless if they are isovalent or aliovalent to Pb(2+), increases the correlation length of antiferrodistortive order (BO6 tilts), which in turn assists the development of double-perovskite structure with coherent local polar distortions. A-site doping with aliovalent cations (Bi(3+)) having the same outermost electron shell and ionic radius as the host A

  13. The effect of chemical variations on the structural polarity of relaxor ferroelectrics studied by resonance Raman spectroscopy

    Science.gov (United States)

    Rohrbeck, A.; de la Flor, G.; Aroyo, M. I.; Gospodinov, M.; Bismayer, U.; Mihailova, B.

    2016-11-01

    Resonance Raman spectroscopy was applied to doped PbSc0.5Ta0.5O3 and PbSc0.5Nb0.5O3 relaxor ferroelectrics, to better understand the effect of composition disorder on the mesoscopic-scale polar order in complex perovskite-type (ABO3) ferroelectrics. The excitation photon energy used was 3.8 eV, which is slightly above the energy gap and corresponds to the maximum of the optical dielectric permittivity. Group-theory analysis reveals that the resonance Raman scattering (RRS) observed under these conditions is allowed only in polar crystal classes. Therefore, RRS is dominated by the atomic dynamics of nanoregions with coherent polar distortions, which considerably facilitates the comparison of polar order in various compounds. The results show that A-site doping (Ba2+, Sr2+, La3+, Bi3+) has significantly stronger effect on the structural polarity than the introduction of a third element at the B site (Nb5+ or Sn4+ doped in PbSc0.5Ta0.5O3). The A-site substitution by cations that in contrast to Pb2+ have isotropic outermost electron shells disturbs the system of lone-pair electrons, thus reducing the correlation length of coupled polar distortions and the strength of the electric field associated with the mean polarization of polar nanoregions. A-site doping with larger cations (Ba2+) augments the polar deformation of the individual BO6 octahedra due to local elastic fields. As a result, such A-site doping intensifies the initial structural polarity at high temperatures and prevails the enlargement of the polar fraction at low temperatures. A-site doping with smaller cations (Sr2+, La3+), regardless if they are isovalent or aliovalent to Pb2+, increases the correlation length of antiferrodistortive order (BO6 tilts), which in turn assists the development of double-perovskite structure with coherent local polar distortions. A-site doping with aliovalent cations (Bi3+) having the same outermost electron shell and ionic radius as the host A-site Pb2+ cations leads to

  14. The C/O ratio at low metallicity: constraints on early chemical evolution from observations of Galactic halo stars

    CERN Document Server

    Fabbian, D; Asplund, M; Pettini, M; Akerman, C

    2008-01-01

    We present new measurements of the abundances of carbon and oxygen derived from high-excitation C I and O I absorption lines in metal-poor halo stars, with the aim of clarifying the main sources of these two elements in the early stages of the chemical enrichment of the Galaxy. We target 15 new stars compared to our previous study, with an emphasis on additional C/O determinations in the crucial metallicity range -3<[Fe/H]<-2. Departures from local thermodynamic equilibrium were accounted for in the line formation for both carbon and oxygen. The non-LTE effects are very strong at the lowest metallicities but, contrary to what has sometimes been assumed in the past due to a simplified assessment, of different degrees for the two elements. In addition, for the 28 stars with [Fe/H]<-1 previously analysed, stellar parameters were re-derived and non-LTE corrections applied in the same fashion as for the rest of our sample, giving consistent abundances for 43 halo stars in total. The new observations and n...

  15. 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

  16. Study of the footprints of short-term variation in XCO2 observed by TCCON sites using NIES and FLEXPART atmospheric transport models

    Science.gov (United States)

    Belikov, Dmitry A.; Maksyutov, Shamil; Ganshin, Alexander; Zhuravlev, Ruslan; Deutscher, Nicholas M.; Wunch, Debra; Feist, Dietrich G.; Morino, Isamu; Parker, Robert J.; Strong, Kimberly; Yoshida, Yukio; Bril, Andrey; Oshchepkov, Sergey; Boesch, Hartmut; Dubey, Manvendra K.; Griffith, David; Hewson, Will; Kivi, Rigel; Mendonca, Joseph; Notholt, Justus; Schneider, Matthias; Sussmann, Ralf; Velazco, Voltaire A.; Aoki, Shuji

    2017-01-01

    The Total Carbon Column Observing Network (TCCON) is a network of ground-based Fourier transform spectrometers (FTSs) that record near-infrared (NIR) spectra of the sun. From these spectra, accurate and precise observations of CO2 column-averaged dry-air mole fractions (denoted XCO2) are retrieved. TCCON FTS observations have previously been used to validate satellite estimations of XCO2; however, our knowledge of the short-term spatial and temporal variations in XCO2 surrounding the TCCON sites is limited. In this work, we use the National Institute for Environmental Studies (NIES) Eulerian three-dimensional transport model and the FLEXPART (FLEXible PARTicle dispersion model) Lagrangian particle dispersion model (LPDM) to determine the footprints of short-term variations in XCO2 observed by operational, past, future and possible TCCON sites. We propose a footprint-based method for the collocation of satellite and TCCON XCO2 observations and estimate the performance of the method using the NIES model and five GOSAT (Greenhouse Gases Observing Satellite) XCO2 product data sets. Comparison of the proposed approach with a standard geographic method shows a higher number of collocation points and an average bias reduction up to 0.15 ppm for a subset of 16 stations for the period from January 2010 to January 2014. Case studies of the Darwin and Reunion Island sites reveal that when the footprint area is rather curved, non-uniform and significantly different from a geographical rectangular area, the differences between these approaches are more noticeable. This emphasises that the collocation is sensitive to local meteorological conditions and flux distributions.

  17. Suzaku Observations of Spectral Variations of the Ultra Luminous X-ray Source Holmberg IX X-1

    CERN Document Server

    Kobayashi, Shogo B; Makishima, Kazuo

    2016-01-01

    Observations of the Ultra Luminous X-ray source (ULX) Holmberg IX X-1 were carried out with Suzaku twice, once on 2012 April 13 and then on 2012 October 24, with exposures of 180 ks and 217 ks, respectively. The source showed a hard power-law shape spectrum with a mild cutoff at $\\sim 8$ keV, which is typical of ULXs when they are relatively dim. On both occasions, the 0.6-11 keV spectrum was explained successfully in terms a cool ($\\sim 0.2$ keV) multi-color disk blackbody emission model and a thermal Comptonization emission produced by an electron cloud with a relatively low temperature and high optical depth, assuming that a large fraction of the disk-blackbody photons are Comptonized whereas the rest is observed directly. The 0.5-10 keV luminosity was $1.2\\times10^{40}$ erg s$^{-1}$ in April, and $\\sim 14\\%$ higher in October. This brightening was accompanied by spectral softening in $\\ge 2$ keV, with little changes in the $\\le 2$ keV spectral shape. This behavior can be understood if the accretion disk r...

  18. Tracking the Solar Cycle through IBEX Observations of Energetic Neutral Atom Flux Variations at the Heliospheric Poles

    Science.gov (United States)

    Reisenfeld, D. B.; Bzowski, M.; Funsten, H. O.; Fuselier, S. A.; Galli, A.; Janzen, P. H.; Karna, N.; Kubiak, M. A.; McComas, D. J.; Schwadron, N. A.; Sokół, J. M.

    2016-12-01

    With seven years of Interstellar Boundary Explorer (IBEX) observations, from 2009 to 2015, we can now trace the time evolution of heliospheric energetic neutral atoms (ENAs) through over half a solar cycle. At the north and south ecliptic poles, the spacecraft attitude allows for continuous coverage of the ENA flux; thus, signal from these regions has much higher statistical accuracy and time resolution than anywhere else in the sky. By comparing the solar wind dynamic pressure measured at 1 au with the heliosheath plasma pressure derived from the observed ENA fluxes, we show that the heliosheath pressure measured at the poles correlates well with the solar cycle. The analysis requires time-shifting the ENA measurements to account for the travel time out and back from the heliosheath, which allows us to estimate the scale size of the heliosphere in the polar directions. We arrive at an estimated distance to the center of the ENA source region in the north of 220 au and in the south a distance of 190 au. We also find a good correlation between the solar cycle and the ENA energy spectra at the poles. In particular, the ENA flux for the highest IBEX energy channel (4.3 keV) is quite closely correlated with the areas of the polar coronal holes, in both the north and south, consistent with the notion that polar ENAs at this energy originate from pickup ions of the very high speed wind (˜700 km s-1) that emanates from polar coronal holes.

  19. 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 (<20-30 m in depth) and the 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.

  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.

  1. Variations in solar radiation in the solar activity cycle: Response of Earth's atmospheric parameters (numerical modeling and analysis of observational data)

    Science.gov (United States)

    Krivolutsky, A. A.; Dement'eva, A. V.; Kukoleva, A. A.

    2016-12-01

    The results of a three-dimensional numerical simulation of changes in the temperature and wind within a height range of up to 100 km caused by changes in fluxes in the solar ultraviolet (UV) radiation in the 23rd solar activity cycle (which was characterized by unusually low values of UV-radiation fluxes) and also of global changes in the ozone content are presented. The simulation results showed that the response of the temperature to variations in the UV radiation are substantially of a nonzonal character, which is caused by the presence in the model of sources of quasi-stationary waves corresponding to the observational data.

  2. 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.

  3. 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.

  4. Suzaku observations of spectral variations of the ultra-luminous X-ray source Holmberg IX X-1

    Science.gov (United States)

    Kobayashi, Shogo B.; Nakazawa, Kazuhiro; Makishima, Kazuo

    2017-02-01

    Observations of the ultra-luminous X-ray source (ULX) Holmberg IX X-1 were carried out with Suzaku twice, once on 2012 April 13 and then on 2012 October 24, with exposures of 180 ks and 217 ks, respectively. The source showed a hard power-law shaped spectrum with a mild cutoff at ˜8 keV, which is typical of ULXs when they are relatively dim. On both occasions, the 0.6-11 keV spectrum was explained successfully in terms of a cool (˜0.2 keV) multi-color disk blackbody emission model and thermal Comptonization emission produced by an electron cloud with a relatively low temperature and high optical depth, assuming that a large fraction of the disk-blackbody photons are Comptonized whereas the rest are observed directly. The 0.5-10 keV luminosity was 1.2 × 1040 erg s-1 in April, and ˜14% higher in October. This brightening was accompanied by spectral softening in ≥2 keV, with little change in the ≤2 keV spectral shape. This behavior can be understood if the accretion disk remains unchanged while the electron cloud covers a variable fraction of the disk. The absorbing column density was consistent with the galactic line-of sight value, and did not vary by more than 1.6 × 1021 cm-2. Together with the featureless spectra, these properties may not be reconciled easily with the super-critical accretion scenario of this source.

  5. Fungal endophytes of Alpinia officinarum rhizomes: insights on diversity and variation across growth years, growth sites, and the inner active chemical concentration.

    Science.gov (United States)

    Shubin, Li; Juan, Huang; RenChao, Zhou; ShiRu, Xu; YuanXiao, Jin

    2014-01-01

    In the present study, the terminal-restriction fragment length polymorphism (T-RFLP) technique, combined with the use of a clone library, was applied to assess the baseline diversity of fungal endophyte communities associated with rhizomes of Alpinia officinarum Hance, a medicinal plant with a long history of use. A total of 46 distinct T-RFLP fragment peaks were detected using HhaI or MspI mono-digestion-targeted, amplified fungal rDNA ITS sequences from A. officinarum rhizomes. Cloning and sequencing of representative sequences resulted in the detection of members of 10 fungal genera: Pestalotiopsis, Sebacina, Penicillium, Marasmius, Fusarium, Exserohilum, Mycoleptodiscus, Colletotrichum, Meyerozyma, and Scopulariopsis. The T-RFLP profiles revealed an influence of growth year of the host plant on fungal endophyte communities in rhizomes of this plant species; whereas, the geographic location where A. officinarum was grown contributed to only limited variation in the fungal endophyte communities of the host tissue. Furthermore, non-metric multidimensional scaling (NMDS) analysis across all of the rhizome samples showed that the fungal endophyte community assemblages in the rhizome samples could be grouped according to the presence of two types of active indicator chemicals: total volatile oils and galangin. Our present results, for the first time, address a diverse fungal endophyte community is able to internally colonize the rhizome tissue of A. officinarum. The diversity of the fungal endophytes found in the A. officinarum rhizome appeared to be closely correlated with the accumulation of active chemicals in the host plant tissue. The present study also provides the first systematic overview of the fungal endophyte communities in plant rhizome tissue using a culture-independent method.

  6. 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

  7. Observed Climatic Variations in the Growing Season of Field Crops in Northeast China from 1992 to 2012

    Institute of Scientific and Technical Information of China (English)

    LIU Yang; JIANG Wen-lai; XIAO Bi-lin; LEI Bo

    2014-01-01

    To determine the potential effects of climate change on crop phenological development and productivity, an integrated analysis was conducted based on the observed climatic and phenological records of Northeast China from 1992 to 2012. A set of quality assurance procedures, including repeated record checks, agro-meteorological station selection, internal consistency checks, temporal outlier checks, spatial outlier checks, and interpolation of missing data, were designed and applied to the phenology datasets of spring maize and paddy rice. Our results indicated that almost all phenological dates of spring maize and paddy rice became increasingly delayed from 1992 to 2012. The duration of the growing season was prolonged, particularly for the grain-iflling stage (GS3). The prolonged growing season was beneifcial to productivity. For spring maize, the average precipitation during GS3 decreased at a rate of 27.46 mm/decade, and the annual accumulated temperature over 10°C increased at a rate of 31.07°C/decade. Farmers initiatively adjusted crop cultivars and selected drought-resistant crops to cope with the challenges of drought.

  8. Variations of the ISM Conditions Across the Main Sequence of Star-Forming Galaxies: Observations and Simulations

    CERN Document Server

    Martínez-Galarza, Juan R; Lanz, Lauranne; Hayward, Christopher C; Zezas, Andreas; Rosenthal, Lee; Weiner, Aaron; Hung, Chao-Ling; Ashby, Matthew L N; Groves, Brent

    2014-01-01

    (abridged) Significant evidence has been gathered suggesting the existence of a main sequence (MS) of star-forming galaxies that relates their star formation rate and their stellar mass: $SFR \\propto M_*^{\\alpha}$. Several ideas have been suggested to explain fundamental properties of the MS, such as its slope, its dispersion, and its evolution with redshift. However, no consensus has been reached regarding its true nature, or whether the membership of particular galaxies to this MS implies the existence of two different modes of star formation. In order to advance our understanding of the MS, here we use a statistically robust Bayesian Spectral Energy Distribution (SED) analysis (CHIBURST) to consistently analyze the star-forming properties of a set of hydro-dynamical simulations of mergers, as well as observations of real mergers and luminous galaxies, both local and at intermediate redshift. We find a very tight correlation between the specific star formation rate (sSFR) of our fitted galaxies, and the typ...

  9. 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.

  10. Observation of the variations of the domain structure of a spontaneous electric field in a two-dimensional electron system under microwave irradiation

    Science.gov (United States)

    Dorozhkin, S. I.; Umansky, V.; von Klitzing, K.; Smet, J. H.

    2016-11-01

    It has been found on a sample of the GaAs/AlGaAs heterostructure with the two-dimensional electron system that different configurations of domains of a spontaneous electric field are possible within one microwave- induced state with the resistance tending to zero. Transitions between such configurations are observed at the variation of the radiation power and magnetic field. In the general case, the configuration of domains is more complicated than existing models. The fragment of the distribution of the electric field in the sample for one of the observed configurations is in agreement with the rhombic domain structure considered by I. G. Finkler and B. I. Halperin, Phys. Rev. B 79, 085315 (2009).

  11. Long repetition time experiments for measurement of concentrations in systems with chemical exchange and undergoing temporal variation-comparison of methods with and without correction for saturation

    Science.gov (United States)

    Galbán, Craig J.; Spencer, Richard G. S.

    2003-02-01

    The purpose of this paper is to compare two methods for quantifying metabolite concentrations using the one-pulse experiment for a sample undergoing chemical exchange and subject to an intervention or other temporal variation. The methods, LATR-C (Long Acquisition TR (interpulse delay); Corrected for partial saturation) and LATR-NC (Long Acquisition TR; Not Corrected), are compared in terms of signal-to-noise ratio, SNR, per unit time and quantitation errors. Parameters relevant to the isolated perfused rat heart are used as a specific application, although the results are general. We assume throughout that spin-lattice relaxation times, T1, do not change. For a given flip angle, θ, TR's are calculated which result in maximal SNR per unit time under 10%, 5%, and 1% constraints on quantitation errors. Additional simulations were performed to demonstrate explicitly the dependence of the quantitation errors on TR for a fixed θ. We find (i) if the allowed error is large, and when both metabolite concentrations and rate constants vary, LATR-C permits use of shorter TR, and hence yields greater SNR per unit time, than LATR-NC; (ii) for small allowed error, the two methods give similar TR's and SNR per unit time, so that the simpler LATR-NC experiment may be preferred; (iii) large values of θ result in similar constrained TR's and hence SNR per unit time for the two methods; (iv) the ratio of concentrations of metabolites with similar T1 exhibit similar errors for the two methods.

  12. Variations in the chemical composition of lamprophyllite-group minerals and the crystal structure of fluorine-rich barytolamprophyllite from new peralkaline dyke

    Science.gov (United States)

    Akimenko, M. I.; Aksenov, S. M.; Sorokhtina, N. V.; Kogarko, L. N.; Kononkova, N. N.; Rastsvetaeva, R. K.; Rozenberg, K. A.

    2015-11-01

    The variations in the chemical composition of lamprophyllite-group minerals from a peralkaline dyke of the Mokhnatye Roga area (Kandalaksha region, Kola Peninsula), which are crystallized during the entire period of dyke formation and form several generations, have been investigated. The early generations differ in a steadily high fluorine content, while the later ones exhibit reduced amount of fluorine, impurity elements, and sodium, with a simultaneous increase in the potassium content. The crystal structure of fluorine- rich barytolamprophyllite (potentially a new representative of the lamprophyllite group, differing by the predominance of fluorine in the anion X site) has been analyzed by single crystal X-ray diffraction. This mineral is found to have a monoclinic unit cell with the following parameters: a = 19.5219(8) Å, b = 7.0915(2) Å, c = 5.3925(2) Å, β = 96.628(3)°, and sp. gr. C2/ m. The structure is refined to R = 5.73% in the anisotropic approximation of the atomic displacement parameters using 3668 I > 2σ( I). The idealized formula ( Z = 2) is (Ba,Sr)2[Na(Na,Fe)2(Ti,Mg)F2][Ti2(Si2O7)2O2].

  13. Seasonal Ozone Variations in the Isentropic Layer between 330 and 380 K as Observed by SAGE 2: Implications of Extratropical Cross-Tropopause Transport

    Science.gov (United States)

    Wang, Pi-Huan; Cunnold, Derek M.; Zawodny, Joseph M.; Pierce, R. Bradley; Olson, Jennifer R.; Kent, Geoffrey S.; Skeens, Kristi, M.

    1998-01-01

    To provide observational evidence on the extratropical cross-tropopause transport between the stratosphere and the troposphere via quasi-isentropic processes in the middleworld (the part of the atmosphere in which the isentropic surfaces intersect the tropopause), this report presents an analysis of the seasonal variations of the ozone latitudinal distribution in the isentropic layer between 330 K and 380 K based on the measurements from the Stratospheric Aerosol and Gas Experiment (SAGE) II. The results from SAGE II data analysis are consistent with (1) the buildup of ozone-rich air in the extratropical middleworld through the large-scale descending mass circulation during winter, (2) the spread of ozone-rich air in the isentropic layer from midlatitudes to subtropics via quasi-isentropic transport during spring, (3) significant photochemical ozone removal and the absence of an ozone-rich supply of air to the layer during summer, and (4) air mass exchange between the subtropics and the extratropics during the summer monsoon period. Thus the SAGE II observed ozone seasonal variations in the middleworld are consistent with the existing model calculated annual cycle of the diabatic circulation as well as the conceptual role of the eddy quasi-adiabatic transport in the stratosphere-troposphere exchange reported in the literature.

  14. An Optimal Sampling Design for Observing and Validating Long-Term Leaf Area Index with Temporal Variations in Spatial Heterogeneities

    Directory of Open Access Journals (Sweden)

    Yelu Zeng

    2015-01-01

    Full Text Available A sampling strategy to define elementary sampling units (ESUs for an entire site at the kilometer scale is an important step in the validation process for moderate-resolution leaf area index (LAI products. Current LAI-sampling strategies are unable to consider the vegetation seasonal changes and are better suited for single-day LAI product validation, whereas the increasingly used wireless sensor network for LAI measurement (LAINet requires an optimal sampling strategy across both spatial and temporal scales. In this study, we developed an efficient and robust LAI Sampling strategy based on Multi-temporal Prior knowledge (SMP for long-term, fixed-position LAI observations. The SMP approach employed multi-temporal vegetation index (VI maps and the vegetation classification map as a priori knowledge. The SMP approach minimized the multi-temporal bias of the VI frequency histogram between the ESUs and the entire site and maximized the nearest-neighbor index to ensure that ESUs were dispersed in the geographical space. The SMP approach was compared with four sampling strategies including random sampling, systematic sampling, sampling based on the land-cover map and a sampling strategy based on vegetation index prior knowledge using the PROSAIL model-based simulation analysis in the Heihe River basin. The results indicate that the ESUs selected using the SMP method spread more evenly in both the multi-temporal feature space and geographical space over the vegetation cycle. By considering the temporal changes in heterogeneity, the average root-mean-square error (RMSE of the LAI reference maps can be reduced from 0.12 to 0.05, and the relative error can be reduced from 6.1% to 2.2%. The SMP technique was applied to assign the LAINet ESU locations at the Huailai Remote Sensing Experimental Station in Beijing, China, from 4 July to 28 August 2013, to validate three MODIS C5 LAI products. The results suggest that the average R2, RMSE, bias and relative

  15. Slope topography-induced spatial variation correlation with observed building damages in Corso during the May 21, 2003, M w 6.8, Boumerdes earthquake (Algeria)

    Science.gov (United States)

    Messaoudi, Akila; Laouami, Nasser; Mezouar, Nourredine

    2017-01-01

    During the May 21, 2003 M w 6.8 Boumerdes earthquake, in the "Cité des 102 Logements" built on a hilltop, in Corso, heavy damages were observed: near the crest, a four-story RC building collapsed while others experienced severe structural damage and far from the crest, slight damage was observed. In the present paper, we perform a 2D slope topography seismic analysis and investigate its effects on the response at the plateau as well as the correlation with the observed damage distribution. A site-specific seismic scenario is used involving seismological, geological, and geotechnical data. 2D finite element numerical seismic study of the idealized Corso site subjected to vertical SV wave propagation is carried out by the universal code FLUSH. The results highlighted the main factors that explain the causes of block collapse, located 8-26 m far from the crest. These are as follows: (i) a significant spatial variation of ground response along the plateau due to the topographic effect, (ii) this spatial variation presents high loss of coherence, (iii) the seismic ground responses (PGA and response spectra) reach their maxima, and (iv) the fundamental frequency of the collapsed blocks coincides with the frequency content of the topographic component. For distances far from the crest where slight damages were observed, the topographic contribution is found negligible. On the basis of these results, it is important to take into account the topographic effect and the induced spatial variability in the seismic design of structures sited near the crest of slope.

  16. Routine hydrography and chemical observations in Lake Nitinat, British Columbia, from 1964 to 1975 (NCEI Accession 7800331)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This report contains all of the routine hydrographic and chemical measurements obtained from Lake Nitinat. British Columbia on cruises from 1964 to 1975. In...

  17. Chemical abundances in the protoplanetary disc LV 2 (Orion) - II. High-dispersion VLT observations and microjet properties

    Science.gov (United States)

    Tsamis, Y. G.; Walsh, J. R.

    2011-11-01

    Integral field spectroscopy of the LV 2 proplyd is presented taken with the Very Large Telescope (VLT)/FLAMES Argus array at an angular resolution of 0.31 × 0.31 arcsec2 and velocity resolutions down to 2 km s-1 pixel-1. Following subtraction of the local M42 emission, the spectrum of LV 2 is isolated from the surrounding nebula. We measured the heliocentric velocities and widths of a number of lines detected in the intrinsic spectrum of the proplyd, as well as in the adjacent Orion nebula falling within a 6.6 × 4.2 arcsec2 field of view. It is found that far-ultraviolet to optical collisional lines with critical densities, Ncr, ranging from 103 to 109 cm-3 suffer collisional de-excitation near the rest velocity of the proplyd correlating tightly with their critical densities. Lines of low Ncr are suppressed the most. The bipolar jet arising from LV 2 is spectrally and spatially well detected in several emission lines. We compute the [O III] electron temperature profile across LV 2 in velocity space and measure steep temperature variations associated with the red-shifted lobe of the jet, possibly being due to a shock discontinuity. From the velocity-resolved analysis the ionized gas near the rest frame of LV 2 has Te= 9200 ± 800 K and Ne˜ 106 cm-3, while the red-shifted jet lobe has Te≈ 9000-104 K and Ne˜ 106-107 cm-3. The jet flow is highly ionized but contains dense semineutral clumps emitting neutral oxygen lines. The abundances of N+, O2 +, Ne2 +, Fe2 +, S+and S2 +are measured for the strong red-shifted jet lobe. Iron in the core of LV 2 is depleted by 2.54 dex with respect to solar as a result of sedimentation on dust, whereas the efficient destruction of dust grains in the fast microjet raises its Fe abundance to at least 30 per cent solar. Sulphur does not show evidence of significant depletion on dust, but its abundance both in the core and the jet is only about half solar. Based on observations made with ESO telescopes at the Paranal Observatory

  18. Interrelated variations of O3, CO and deep convection in the tropical/subtropical upper troposphere observed by the Aura Microwave Limb Sounder (MLS during 2004–2011

    Directory of Open Access Journals (Sweden)

    L. Froidevaux

    2012-07-01

    Full Text Available The interrelated geographical and temporal variability seen in more than seven years of tropical and subtropical upper tropospheric (215 hPa ozone, carbon monoxide and cloud ice water content (IWC observations by the Aura Microwave Limb Sounder (MLS are presented. Observed ozone abundances and their variability (geographical and temporal agree to within 10–15 ppbv with records from sonde observations. MLS complements these (and other observations with global coverage and simultaneous measurements of related parameters. Previously-reported phenomena such as the ozone "wave one" feature are clearly seen in the MLS observations, as is a double peak in ozone abundance over tropical East Africa, with enhanced abundances in both May to June and September to November. While repeatable seasonal cycles are seen in many regions, they are often accompanied by significant interannual variability. Ozone seasonal cycles in the southern tropics and subtropics tend to be more distinct (i.e., annually repeatable than in the northern. By contrast, carbon monoxide shows distinct seasonal cycles in many northern subtropical regions, notably from India to the Eastern Pacific. Deep convection (as indicated by large values of IWC is typically associated with reductions in upper tropospheric ozone. Convection over polluted regions is seen to significantly enhance upper tropospheric carbon monoxide. While some regions show statistically significant correlations among ozone, carbon monoxide and IWC, simple correlations fall well short of accounting for the observed variability. The observed interrelated variations and metrics of annual and interannual variability described here represent a new resource for validation of atmospheric chemistry models.

  19. Interrelated variations of O3, CO and deep convection in the tropical/subtropical upper troposphere observed by the Aura Microwave Limb Sounder (MLS during 2004–2011

    Directory of Open Access Journals (Sweden)

    L. Froidevaux

    2013-01-01

    Full Text Available The interrelated geographic and temporal variability seen in more than seven years of tropical and subtropical upper tropospheric (215 hPa ozone, carbon monoxide and cloud ice water content (IWC observations by the Aura Microwave Limb Sounder (MLS are presented. Observed ozone abundances and their variability (geographic and temporal agree to within 10–15 ppbv with records from sonde observations. MLS complements these (and other observations with global coverage and simultaneous measurements of related parameters. Previously-reported phenomena such as the ozone "wave one" feature are clearly seen in the MLS observations, as is a double peak in ozone abundance over tropical East Africa, with enhanced abundances in both May to June and September to November. While repeatable seasonal cycles are seen in many regions, they are often accompanied by significant interannual variability. Ozone seasonal cycles in the southern tropics and subtropics tend to be more distinct (i.e., annually repeatable than in the northern. By contrast, carbon monoxide shows distinct seasonal cycles in many northern subtropical regions, notably from India to the Eastern Pacific. Deep convection (as indicated by large values of IWC is typically associated with reductions in upper tropospheric ozone. Convection over polluted regions is seen to significantly enhance upper tropospheric carbon monoxide. While some regions show statistically significant correlations among ozone, carbon monoxide and IWC, simple correlations fall well short of accounting for the observed variability. The observed interrelated variations and metrics of annual and interannual variability described here represent a new resource for validation of atmospheric chemistry models.

  20. Variational Assimilation of GPS Precipitable Water Vapor and Hourly Rainfall Observations for a Meso-β Scale Heavy Precipitation Event During the 2002 Mei-Yu Season

    Institute of Scientific and Technical Information of China (English)

    ZHANG Meng; NI Yunqi; ZHANG Fuqing

    2007-01-01

    Recent advances in Global Positioning System (GPS) remote sensing technology allow for a direct estimation of the precipitable water vapor (PWV) from delayed signals transmitted by GPS satellites, which can be assimilated into numerical models with four-dimensional variational (4DVAR) data assimilation. A mesoscale model and its 4DVAR system are used to access the impacts of assimilating GPS-PWV and hourly rainfall observations on the short-range prediction of a heavy rainfall event on 20 June 2002. The heavy precipitation was induced by a sequence of meso-β-scale convective systems (MCS) along the mei-yu front in China.The experiments with GPS-PWV assimilation successfully simulated the evolution of the observed MCS cluster and also eliminated the erroneous rainfall systems found in the experiment without 4DVAR assimilation. Experiments with hourly rainfall assimilation performed similarly both on the prediction of MCS initiation and the elimination of erroneous systems, however the MCS dissipated much sooner than it did in observations. It is found that the assimilation-induced moisture perturbation and mesoscale low-level jet are helpful for the MCS generation and development. It is also discovered that spurious gravity waves may post serious limitations for the current 4DVAR algorithm, which would degrade the assimilation efficiency, especially for rainfall data. Sensitivity experiments with different observations, assimilation windows and observation weightings suggest that assimilating GPS-PWV can be quite effective, even with the assimilation window as short as 1 h. On the other hand, assimilating rainfall observations requires extreme cautions on the selection of observation weightings and the control of spurious gravity waves.

  1. Inter-comparison of Seasonal Variation, Chemical Characteristics, and Source Identification of Atmospheric Fine Particles on Both Sides of the Taiwan Strait

    Science.gov (United States)

    Li, Tsung-Chang; Yuan, Chung-Shin; Huang, Hu-Ching; Lee, Chon-Lin; Wu, Shui-Ping; Tong, Chuan

    2016-01-01

    The spatiotemporal distribution and chemical composition of atmospheric fine particles in areas around the Taiwan Strait were firstly investigated. Fine particles (PM2.5) were simultaneously collected at two sites on the west-side, one site at an offshore island, and three sites on the east-side of the Taiwan Strait in 2013–2014. Field sampling results indicated that the average PM2.5 concentrations at the west-side sampling sites were generally higher than those at the east-side sampling sites. In terms of chemical composition, the most abundant water-soluble ionic species of PM2.5 were SO42−, NO3−, and NH4+, while natural crustal elements dominated the metallic content of PM2.5, and the most abundant anthropogenic metals of PM2.5 were Pb, Ni and Zn. Moreover, high OC/EC ratios of PM2.5 were commonly observed at the west-side sampling sites, which are located at the downwind of major stationary sources. Results from CMB receptor modeling showed that the major sources of PM2.5 were anthropogenic sources and secondary aerosols at the both sides, and natural sources dominated PM2.5 at the offshore site. A consistent decrease of secondary sulfate and nitrate contribution to PM2.5 suggested the transportation of aged particles from the west-side to the east-side of the Taiwan Strait. PMID:26973085

  2. Miocene to recent ice elevation variations from the interior of the West Antarctic ice sheet: Constraints from geologic observations, cosmogenic nuclides and ice sheet modeling

    Science.gov (United States)

    Mukhopadhyay, Sujoy; Ackert, Robert P.; Pope, Allen E.; Pollard, David; DeConto, Robert M.

    2012-07-01

    Observations of long-term West Antarctic Ice Sheet (WAIS) behavior can be used to test and constrain dynamic ice sheet models. Long-term observational constraints are however, rare. Here we present the first constraints on long-term (Miocene-Holocene) WAIS elevation from the interior of the ice sheet near the WAIS divide. We use geologic observations and measurements of cosmogenic 21Ne and 10Be in bedrock surfaces to constrain WAIS elevation variations to WAIS elevations to have been similar to, or lower than present, since the beginning of the Pliocene warm period. We use a continental ice sheet model to simulate the history of ice cover at our sampling sites and thereby compute the expected concentration of the cosmogenic nuclides. The ice sheet model indicates that during the past 5 Ma interior WAIS elevations of >65 m above present-day ice levels at the Ohio Range occur only rarely during brief ice sheet highstands, consistent with the observed cosmogenic nuclide data. Furthermore, the model's prediction that highstand elevations have increased on average since the Pliocene is in good agreement with the cosmogenic nuclide data that indicate the highest ice elevation over the past 5 Ma was reached during the highstand at 11 ka. Since the simulated cosmogenic nuclide concentrations derived from the model's ice elevation history are in good agreement with our measurements, we suggest that the model's prediction of more frequent collapsed-WAIS states and smaller WAIS volumes during the Pliocene are also correct.

  3. Inter-annual variation of chlorophyll in the northern South China Sea observed at the SEATS Station and its asymmetric responses to climate oscillation

    Directory of Open Access Journals (Sweden)

    K.-K. Liu

    2013-04-01

    Full Text Available It is widely recognized that the variation of average surface chlorophyll a concentration (Chl in the South China Sea (SCS is closely related to wind forcing, especially during the intense winter monsoon. In this study we demonstrate that, after removal of the seasonal cycles, the variation of Chl showed strong asymmetric responses to wind speed under El Niño or La Niña conditions. The analysis was based on a time-series of Chl in the study area (115–117° E, 17–19° N around the SEATS (South-East Asian Time-series Study station located in the central northern SCS from September 1997 to the end of 2011, which was constructed by merging the SeaWiFS data (1997–2006 and MODIS data (2003–2011. The merged daily data were validated by shipboard observations at the SEATS station. The non-seasonal variations of monthly mean Chl, wind speed, sea surface height (SSH and sea surface temperature (SST were examined against the multivariate ENSO index (MEI. The analysis reveals strongly asymmetric correlations of Chl and SST with positive MEI (El Niño or negative MEI (La Niña. Under El Niño conditions, both showed significant correlations with MEI or wind speed; under La Niña conditions, both showed weak or insignificant correlations. The contrast was more pronounced for Chl than for SST. The subdued responses of Chl to wind forcing under La Niña conditions were probably attributed to a deepened thermocline, for which wind driven nutrient pumping is less efficient. A deeper thermocline, which was observed during the 1999–2000 La Niña event and inferred by positive SSH anomalies during other La Niña events, was probably caused by reduced SCS throughflow under La Niña conditions. Intrusion of the nutrient-depleted Kuroshio water in the surface layer as observed during the 1999–2000 La Niña could be partially responsible for the suppressed Chl response.

  4. DETERMINING THE ROLE OF INDIVIDUAL FLY ASH PARTICLES IN INFLUENCING THE VARIATION IN THE OVERALL PHYSICAL, MORPHOLOGICAL, AND CHEMICAL PROPERTIES OF FLY ASH

    Directory of Open Access Journals (Sweden)

    Usman Haider

    2016-08-01

    Full Text Available The properties of fly ashes vary because of the differences in the properties of their individual particles, and the determination of variation in these properties is of interest to the industries which use pulverized raw fly ash in applications, such as in cementitious materials and in the recovery of certain rare elements from raw fly ash. To investigate the differences in individual particles, four pulverized raw fly ashes from thermal power plants of the Czech Republic were used in this research. It was observed from FE-SEM that all four fly ashes consist of glassy hollow spherical, solid spherical, porous spherical, bright spherical, porous slaggy and compact slaggy particles. Box and whisker diagrams were plotted from the data of EDX individual particle analyses, which showed that the data of percentages for the Si, Al, and Fe elements is more scattered as compared to other elements. It was further observed from ternary phase diagrams and pseudo coloured images, that nature of fly ash particles changes from alumino silicate glassy to alumino silicate calcite metallic to pure ferro-metallic,where glassy particles showed high percentages and pure calcite particles were absent in fly ashes. Furthermore, a comparison between the XRF, the EDX total area analyses, showed that the EDX individual particle analysis gives more realistic and reliable data with median, mean, and the standard deviation for percentages of each element present in the fly ashes.

  5. Seasonal and spatial variation of trace elements in multi-size airborne particulate matters of Beijing, China: Mass concentration, enrichment characteristics, source apportionment, chemical speciation and bioavailability

    Science.gov (United States)

    Gao, Jiajia; Tian, Hezhong; Cheng, Ke; Lu, Long; Wang, Yuxuan; Wu, Ye; Zhu, Chuanyong; Liu, Kaiyun; Zhou, Junrui; Liu, Xingang; Chen, Jing; Hao, Jiming

    2014-12-01

    The seasonal and spatial variation characteristics of 19 elements (Al, As, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, S, Sb, Se, Zn) in TSP/PM10/PM2.5 samples were investigated, which were collected from April 2011 to January 2012 simultaneously at an urban downtown site, a traffic roadside site, a suburban site, and a rural site in Beijing. The elevated concentrations of several toxic trace elements (As, Cd, Mn, Ni, Pb, etc.) in particles revealed that the contamination of toxic elements in Beijing could not be neglected. Positive matrix factorization method (PMF) was applied for source apportionment of trace elements in PM, and three factors (crust related sources, combustion sources, and traffic and steel industrial related sources) were identified. Furthermore, the chemical speciation and bioavailability of various elements were identified by applying European Community Bureau of Reference (BCR) procedure. Our results showed that eight toxic elements (As, Cd, Cr, Cu, Ni, Pb, Sb and Zn) exhibited higher mobility in PM2.5 than in PM10. Notably, elements of As, Cd, Pb and Zn were presented with higher mobility than the other elements, and these elements were lightly to release into the environment and easily available to human body. Additionally, As, Cd, Pb and Zn also accounted for higher percentages in the bound to mobile fractions at the central urban areas of Beijing. Therefore, special concerns should be paid to these toxic trace elements which had relatively high mobility in fine particles, when planning and implementing the comprehensive air pollution mitigation policies in Beijing.

  6. Three-dimensional analytical model for the spatial variation of the foreshock electron distribution function - Systematics and comparisons with ISEE observations

    Science.gov (United States)

    Fitzenreiter, R. J.; Scudder, J. D.; Klimas, A. J.

    1990-01-01

    A model which is consistent with the solar wind and shock surface boundary conditions for the foreshock electron distribution in the absence of wave-particle effects is formulated for an arbitrary location behind the magnetic tangent to the earth's bow shock. Variations of the gyrophase-averaged velocity distribution are compared and contrasted with in situ ISEE observations. It is found that magnetic mirroring of solar wind electrons is the most important process by which nonmonotonic reduced electron distributions in the foreshock are produced. Leakage of particles from the magnetosheath is shown to be relatively unimportant in determining reduced distributions that are nonmonotonic. The two-dimensional distribution function off the magnetic field direction is the crucial contribution in producing reduced distributions which have beams. The time scale for modification of the electron velocity distribution in velocity space can be significantly influenced by steady state spatial gradients in the background imposed by the curved shock geometry.

  7. Variations in the dip properties of the low-mass X-ray binary XB 1254-69 observed with XMM-Newton and INTEGRAL

    CERN Document Server

    Trigo, M Diaz; Boirin, L; Motch, C; Talavera, A; Balman, S

    2008-01-01

    We have analysed data from five XMM-Newton observations of XB 1254-69, one of them simultaneous with INTEGRAL, to investigate the mechanism responsible for the highly variable dips durations and depths seen from this low-mass X-ray binary. Deep dips were present during two observations, shallow dips during one and no dips were detected during the remaining two observations. At high (1-4 s) time resolution ``shallow dips'' are seen to include a few, very rapid, deep dips whilst the ``deep'' dips consist of many similar very rapid, deep, fluctuations. The folded V-band Optical Monitor light curves obtained when the source was undergoing deep, shallow and no detectable dipping exhibit sinusoid-like variations with different amplitudes and phases. We fit EPIC spectra obtained from "persistent" or dip-free intervals with a model consisting of disc-blackbody and thermal comptonisation components together with Gaussian emission features at 1 and 6.6 keV modified by absorption due to cold and photo-ionised material. ...

  8. Geomagnetic Secular Variation in Texas over the Last 17,000 Years: High-Intensity Geomagnetic Field 'Spike' Observed at ca. 3000 cal BP

    Science.gov (United States)

    Bourne, M. D.; Feinberg, J. M.; Waters, M. R.; Stafford, T. W., Jr.; Forman, S. L.; Lundelius, E. L.

    2015-12-01

    By observing the fluctuations in direction and intensity of the Earth's magnetic field through time, we increase our understanding of the fluid motions in the Earth's outer core that sustain the geomagnetic field, the geodynamo. Recent archaeomagnetic studies in the Near East have proposed extremely rapid increases - 'spikes' - in geomagnetic field intensity ca. 3000 years ago that have proved problematic for our current understanding of core-flow. However, until now, these geomagnetic spikes had not been observed outside of the Near East, where they have been found in metallurgical slag and mud brick walls. We present a new fully-oriented, geomagnetic secular variation and relative palaeointensity (RPI) record for the last 17,000 years from Hall's Cave, Texas. Sediment washed into the cave has formed a continuous stratigraphic sequence that is at least 3.5 m thick. Within the stable, cool climate of the cave, pedogenic and bioturbation processes are almost non-existent, thereby limiting post-depositional physical and geochemical alteration of the magnetic record. The sub-aerial and subterranean setting of the sedimentary sequence in Hall's Cave enabled us to collect oriented palaeomagnetic cubes from an excavated section through the sequence. The palaeomagnetic samples yielded high-quality vectors. An age model for the sequence, determined using 57 AMS 14C-dates on individual bones from microvertebrate, was combined with the palaeomagnetic data to construct a secular variation record. The record is in broad agreement with predictions by Holocene field models for the site's location. However, at ca. 3000 years ago, the RPI data indicate an almost four-fold increase in geomagnetic field intensity lasting several hundred years and contemporaneous with the more short-lived, decadal-scale spikes reported from the Near East. Evidence for this extreme intensity event outside of the Near East has major implications for our current understanding of core-dynamics.

  9. Temporal variations of the segmentation of slow to intermediate spreading mid-ocean ridges 1. Synoptic observations based on satellite altimetry data

    Science.gov (United States)

    Briais, Anne; Rabinowicz, Michel

    2002-05-01

    The high-resolution geoid and gravity maps derived from ERS-1 and Geosat satellite geodetic missions reveal a set of small-scale lineations on the flanks of slow to intermediate spreading mid-ocean ridges. Assuming that these lineations reflect the variations in crustal structure induced by mid-ocean ridge axial discontinuities, we use them to investigate how the discontinuities, and the segments they bound, appear, migrate, and disappear. We provide a synoptic description of the main characteristics of the crustal structure variations, as well as their evolution in time, over the flanks of the Mid-Atlantic, Indian, and Pacific-Antarctic Ridges. The second-order segment length does not appear to vary with the spreading rate for the slow to intermediate spreading ridges investigated here. The amplitude of the gravity signal associated with off-axis discontinuity traces increases with the obliquity of the ridge to spreading and decreases with spreading rate and with the proximity of a ridge section to a hot spot. The patterns of the gravity lineations appear to be very homogeneous over 500- to 1000-km-large corridors bounded by large fracture zones. Far from hot spots, corridors are characterized either by segments bounded by discontinuities migrating back and forth along the axis, implying a lifetime of 10-30 Myr for the segments, or by segments and discontinuities very stable in space and time, surviving for 40-50 Myr. Closer to hot spots, the segmentation is affected in two ways. First, segments tend to migrate along axis away from hot spots, or toward cold spots. Second, asymmetric spreading tends to keep sections of ridges closer to hot spots than normal spreading would. These observations support the hypothesis that ridge segmentation and its evolution are controlled by mantle dynamics. Our analysis provides observational constraints for further models of crustal production along ridges, which are presented in the companion paper by Rabinowicz and Briais [2002].

  10. Reconstruction of past variations of {delta}{sup 13}C in atmospheric CO{sub 2} from i vertical distribution observed in the firn at Dome Fuji, Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Sugawara, S. [Miyagi Univ. of Education, Sendai (Japan). Inst. of Earth Science; Kawamura, K.; Aoki, S.; Nakazawa, T. [Tohoku Univ., Sendai (Japan). Center for Atmospheric and Oceanic Studies; Hashida, G. [National Inst. of Polar Research (Japan)

    2003-04-01

    Temporal variations of {delta}{sup 13}C of atmospheric CO{sub 2} in the past have been reconstructed from the {delta}{sup 13}C values of CO{sub 2} observed in firn at Dome Fuji, Antarctica. The effective diffusivities of CO{sub 2} in firn were estimated for Dome Fuji and another Antarctic site, H72. The age distributions of {sup 13}CO{sub 2} in firn were first calculated by using a one-dimensional diffusion model, and then the past values of the atmospheric {delta}{sup 13}C were derived by using an iterative procedure so that the calculated and observed vertical profiles of {delta}{sup 13}C of CO{sub 2} in firn agreed with each other. This reconstruction method was also applied to the CH{sub 4} concentration to confirm its validity. The values of the atmospheric {delta}{sup 13}C thus estimated were in good agreement with those from direct atmospheric measurements at Syowa Station, Antarctica, even for the levelling off of the secular decrease observed in the first half of the 1990s. The statistical uncertainty of the iterative procedure was examined by adding normal pseudo-random numbers to the observed {delta}{sup 13}C values in firn. We also calculated the {delta}{sup 13}C values for firn at H72 using the reconstructed history of the atmospheric {delta}{sup 13}C, and its vertical profile was found to be in close agreement with the observational result.

  11. Reconstruction of past variations of (delta){sup 13}C in atmospheric CO{sub 2} from i vertical distribution observed in the firn at Dome Fuji, Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Sugawara, S. [Miyagi Univ. of Education, Sendai (Japan). Inst. of Earth Science; Kawamura, K.; Aoki, S.; Nakazawa, T. [Tohoku Univ., Sendai (Japan). Center for Atmospheric and Oceanic Studies; Hashida, G. [National Inst. of Polar Research (Japan)

    2003-04-01

    Temporal variations of (delta){sup 13}C of atmospheric CO{sub 2} in the past have been reconstructed from the (delta){sup 13}C values of CO{sub 2} observed in firn at Dome Fuji, Antarctica. The effective diffusivities of CO{sub 2} in firn were estimated for Dome Fuji and another Antarctic site, H72. The age distributions of {sup 13}CO{sub 2} in firn were first calculated by using a one-dimensional diffusion model, and then the past values of the atmospheric (delta){sup 13}C were derived by using an iterative procedure so that the calculated and observed vertical profiles of (delta){sup 13}C of CO{sub 2} in firn agreed with each other. This reconstruction method was also applied to the CH{sub 4} concentration to confirm its validity. The values of the atmospheric (delta){sup 13}C thus estimated were in good agreement with those from direct atmospheric measurements at Syowa Station, Antarctica, even for the levelling off of the secular decrease observed in the first half of the 1990s. The statistical uncertainty of the iterative procedure was examined by adding normal pseudo-random numbers to the observed (delta){sup 13}C values in firn. We also calculated the (delta){sup 13}C values for firn at H72 using the reconstructed history of the atmospheric (delta){sup 13}C, and its vertical profile was found to be in close agreement with the observational result.

  12. 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)

    C. Shu

    2009-07-01

    Full Text Available The change pattern and trend of soil moisture (SM in the Wuding River basin, Loess Plateau, China is explored based on the simulated long-term SM data from 1956 to 2004 using an eco-hydrological process-based model, Vegetation Interface Processes model, VIP. In-situ SM observations together with a remotely sensed SM dataset retrieved by the Vienna University of Technology are used to validate the model. In the VIP model, climate-eco-hydrological (CEH variables such as precipitation, air temperature and runoff observations and also simulated evapotranspiration (ET, leaf area index (LAI, and vegetation production are used to analyze the soil moisture evolution mechanism. The results show that the model is able to capture seasonal SM variations. The seasonal pattern, multi-year variation, standard deviation and coefficient of variation (CV of SM at the daily, monthly and annual scale are well explained by CEH variables. The annual and inter-annual variability of SM is the lowest compared with that of other CEH variables. The trend analysis shows that SM is in decreasing tendency at α=0.01 level of significance, confirming the Northern Drying phenomenon. This trend can be well explained by the decreasing tendency of precipitation (α=0.1 and increasing tendency of temperature (α=0.01. The decreasing tendency of runoff has higher significance level (α=0.001. Because of SM's decreasing tendency, soil evaporation (ES is also decreasing (α=0.05. The tendency of net radiation (Rn, evapotranspiration (ET, transpiration (EC, canopy intercept (EI is not obvious. Net primary productivity (NPP, of which the significance level is lower than α=0.1, and gross primary productivity (GPP at α=0.01 are in increasing tendency.

  13. Observations about chemical composition of aerosols in the Brazilian Amazon region - Case study: Biomass burning in the subequatorial Amazon region

    Science.gov (United States)

    Gioda, A.; Monteiro, I. L.; Almeida, A. C.; Hacon, S. S.; Dallacort, R.; Ignotti, E.; Godoy, J. M.; Loureiro, A. L.; Morais, F.; Artaxo, P.

    2012-04-01

    The study was carried out in two cities in the Brazilian Amazon region, Tangará da Serra (14 ° 37'10 "S, 57 ° 29'09" W, 427 m asl), located in a transition area between the Amazon biome and the Cerrado and has the characteristics of urban area in Amazon region; and Alta Floresta (9 ° 52 '32 "S, 56 ° 5' 10" W, 283 m asl) situated in the extreme north of the state of Mato Grosso (MT), both in the subequatorial Amazon region. Tangara da Serra has the largest production of sugar cane in the subequatorial Amazon region. They are located 800 km from each other. These two regions are inserted in a region with typical cycles of drought and rain that alter air pollution levels, and lies in the dispersion path of the pollution plume resulting from burnings in the Brazilian Amazon and pollution emanating from neighboring countries. Both cities have wet tropical climate with two well defined seasons: rainy summer (November to May) and dry winter (June to October). During the dry winter, biomass burnings are frequent in these regions. In 2008, the Department of the Environment has banned fires in the period from July 15 to September 15 throughout the State. In this study chemical characterization was performed for approximately 100 aerosol samples collected in each site during 2008. Fine and coarse aerosol samples collected in SFUs were analyzed by ion chromatography for determination of cations (Na+, K+, NH3+, Ca2+ and Mg2+), anions (SO42-, Cl- and NO3-) and organic acids (acetate and formiate) and also measures of black carbon (BC) (Aethalometer). The results showed that for both sites the average concentrations were quite similar for PM2.5 (16 µg/m3), PM10 (11 and 13 µg/m3) and black carbon (1.4 µg/m3 for PM2.5 and 1.6 µg/m3 for PM10). Sulfate was the predominant species in fine (45%) and coarse (26%) particles in both sites. The sulfate concentrations ranged from 0.01-1.92 µg/m3 in PM2.5 and 0.01-1.66 µg/m3 in PM10 in Tangará da Serra and 0.01-2.93 µg/m3 in PM2

  14. Global chemical weather forecasts for field campaign planning: predictions and observations of large-scale features during MINOS, CONTRACE, and INDOEX

    Directory of Open Access Journals (Sweden)

    M. G. Lawrence

    2002-10-01

    Full Text Available The first global tropospheric forecasts of O3 and its precursors have been used in the daily flight planning of field measurement campaigns. The 3-D chemistry-transport model MATCH-MPIC is driven by meteorological data from a weather center (NCEP to produce daily 3-day forecasts of the global distributions of O3 and related gases, as well as regional CO tracers. This paper describes the forecast system and its use in three field campaigns, MINOS, CONTRACE and INDOEX. An overview is given of the forecasts by MATCH-MPIC and by three other chemical weather forecast models (EURAD, ECHAM, and FLEXPART, focusing on O3 and CO. Total CO and regional CO tracers were found to be the most valuable gases for flight plan