WorldWideScience

Sample records for density scale height

  1. Scaling the Salary Heights.

    Science.gov (United States)

    McNamee, Mike

    1986-01-01

    Federal cutbacks have created new demand for fund-raisers everywhere. Educational fund-raisers are thinking about "pay for performance"--incentive-based pay plans that can help them retain, reward, and motivate talented fund raisers within the tight pay scales common at colleges and universities. (MLW)

  2. Scale height determination of spiral galaxies

    Institute of Scientific and Technical Information of China (English)

    计朝晖; 商朝晖; 彭秋和

    1997-01-01

    The method adopted here is based on the rigorous solution of Poison’s equation for logarithmic disturbance density within finite thickness galaxies. After their spiral arms are fitted directly with logarithmic spirals, the morphological parameters, scale heights and their relative errors for 32 spiral galaxies, such as NGC4814, are ob-tained.

  3. Scale heights of 84 northern spiral galaxies

    Institute of Scientific and Technical Information of China (English)

    马骏; 彭秋和

    1997-01-01

    Using the method proposed by Peng (1988) on the basis of density waves theory and the solution of three-dimensional Poisson s equation for a logarithmic disturbance of density,and analyzing the spiral patterns,the scale heights of 84 northern spiral galaxies,whose images are taken from the Digitized Sky Survey at Xinglong Observational Station of Beijing Observatory,are measured.The spiral arms of all these galaxies have been fitted on their photographs with some logarithmic spiral curves for getting their correct inclinations.

  4. Scale Heights of Non-Edge-on Spiral Galaxies

    Institute of Scientific and Technical Information of China (English)

    Tao Hu; Qiu-He Peng; Ying-He Zhao

    2006-01-01

    We present a method of calculating the scale height of non-edge-on spiral galaxies, together with a formula for errors. The method is based on solving Poisson's equation for a logarithmic disturbance of matter density in spiral galaxies. We show that the spiral arms can not extend to inside the "forbidden radius" γ0, due to the effect of the finite thickness of the disk. The method is tested by re-calculating the scale heights of 71 northern spiral galaxies previously calculated by Ma, Peng & Gu.Our results differ from theirs by less than 9%. We also present the scale heights of a further 23 non-edge-on spiral galaxies.

  5. Properties of Star Clusters - II: Scale Height Evolution of Clusters

    CERN Document Server

    Buckner, Anne S M

    2014-01-01

    Until now it has been impossible to observationally measure how star cluster scale height evolves beyond 1Gyr as only small samples have been available. Here we establish a novel method to determine the scale height of a cluster sample using modelled distributions and Kolmogorov-Smirnov tests. This allows us to determine the scale height with a 25% accuracy for samples of 38 clusters or more. We apply our method to investigate the temporal evolution of cluster scale height, using homogeneously selected sub-samples of Kharchenko et al. (MWSC), Dias et al. (DAML02), WEBDA, and Froebrich et al. (FSR). We identify a linear relationship between scale height and log(age/yr) of clusters, considerably different from field stars. The scale height increases from about 40pc at 1Myr to 75pc at 1Gyr, most likely due to internal evolution and external scattering events. After 1Gyr, there is a marked change of the behaviour, with the scale height linearly increasing with log(age/yr) to about 550pc at 3.5Gyr. The most likely...

  6. European Space Science Scales New Heights

    Science.gov (United States)

    1995-06-01

    been approved by all ESA's Member States. Outside Europe, the stability and solidity of Horizon 2000 have made ESA an extremely credible and reliable partner, arousing ever greater interest in international - including transatlantic - co-operation. Given that the first results look positive, it makes sense to think about continuing the work done to date. Which is why this year, half-way through Horizon 2000, it is time to look ahead to the next twenty-year period and embark on the follow-up programme which will lead to further missions being carried out between 2006 and 2016. At ESA Council meeting to be held in October in Toulouse, European ministers responsible for space will therefore have to take a decision on a "Horizon 2000 PLUS " programme designed to ensure successful European space science over a further ten-year period. The proposal being put forward by ESA's directorate of scientific programmes involves setting up three large-scale missions: * a mission to explore Mercury, the least known of the inner solar planets, 60iln of whose surface has yet to be mapped * an interferometry observatory designed to map the sky a hundred times more accurately than the Hipparcos satellite * a gravitational observatory able to pick up the space time waves emitted by the universe at the precise moment of the Big Bang. In parallel four medium-size missions - their content still to be defined - would be carried out. As with its forerunner, Horizon 2000 PLUS has been defined on the basis of proposals submitted by the scientific community following open competition. In all, I10 mission concepts were proposed by a total of 2500 scientists. These were then examined by peer-review groups, involving 75 scientists in all who announced their final choice on I October 1994. The agency is proposing to start preparing for Horizon 2000 PLUS on the basis of level funding up to the year 2000. This means that ESA would undertake to conduct preliminary Horizon 2000 PLUS technological studies

  7. The Impact of Forest Density on Forest Height Inversion Modeling from Polarimetric InSAR Data

    Directory of Open Access Journals (Sweden)

    Changcheng Wang

    2016-03-01

    Full Text Available Forest height is of great significance in analyzing the carbon cycle on a global or a local scale and in reconstructing the accurate forest underlying terrain. Major algorithms for estimating forest height, such as the three-stage inversion process, are depending on the random-volume-over-ground (RVoG model. However, the RVoG model is characterized by a lot of parameters, which influence its applicability in forest height retrieval. Forest density, as an important biophysical parameter, is one of those main influencing factors. However, its influence to the RVoG model has been ignored in relating researches. For this paper, we study the applicability of the RVoG model in forest height retrieval with different forest densities, using the simulated and real Polarimetric Interferometric SAR data. P-band ESAR datasets of the European Space Agency (ESA BioSAR 2008 campaign were selected for experiments. The test site was located in Krycklan River catchment in Northern Sweden. The experimental results show that the forest density clearly affects the inversion accuracy of forest height and ground phase. For the four selected forest stands, with the density increasing from 633 to 1827 stems/Ha, the RMSEs of inversion decrease from 4.6 m to 3.1 m. The RVoG model is not quite applicable for forest height retrieval especially in sparsely vegetated areas. We conclude that the forest stand density is positively related to the estimation accuracy of the ground phase, but negatively correlates to the ground-to-volume scattering ratio.

  8. A linear scale height Chapman model supported by GNSS occultation measurements

    Science.gov (United States)

    Olivares-Pulido, G.; Hernández-Pajares, M.; Aragón-Àngel, A.; Garcia-Rigo, A.

    2016-08-01

    Global Navigation Satellite Systems (GNSS) radio occultations allow the vertical sounding of the Earth's atmosphere, in particular, the ionosphere. The physical observables estimated with this technique permit to test theoretical models of the electron density such as, for example, the Chapman and the Vary-Chap models. The former is characterized by a constant scale height, whereas the latter considers a more general function of the scale height with respect to height. We propose to investigate the feasibility of the Vary-Chap model where the scale height varies linearly with respect to height. In order to test this hypothesis, the scale height data provided by radio occultations from a receiver on board a low Earth orbit (LEO) satellite, obtained by iterating with a local Chapman model at every point of the topside F2 layer provided by the GNSS satellite occultation, are fitted to height data by means of a linear least squares fit (LLS). Results, based on FORMOSAT-3/COSMIC GPS occultation data inverted by means of the Improved Abel transform inversion technique (which takes into account the horizontal electron content gradients) show that the scale height presents a more clear linear trend above the F2 layer peak height, hm, which is in good agreement with the expected linear temperature dependence. Moreover, the parameters of the linear fit obtained during four representative days for all seasons, depend significantly on local time and latitude, strongly suggesting that this approach can significantly contribute to build realistic models of the electron density directly derived from GNSS occultation data.

  9. Topside correction of IRI by global modeling of ionospheric scale height using COSMIC radio occultation data

    Science.gov (United States)

    Wu, M. J.; Guo, P.; Fu, N. F.; Xu, T. L.; Xu, X. S.; Jin, H. L.; Hu, X. G.

    2016-06-01

    The ionosphere scale height is one of the most significant ionospheric parameters, which contains information about the ion and electron temperatures and dynamics in upper ionosphere. In this paper, an empirical orthogonal function (EOF) analysis method is applied to process all the ionospheric radio occultations of GPS/COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) from the year 2007 to 2011 to reconstruct a global ionospheric scale height model. This monthly medium model has spatial resolution of 5° in geomagnetic latitude (-87.5° ~ 87.5°) and temporal resolution of 2 h in local time. EOF analysis preserves the characteristics of scale height quite well in the geomagnetic latitudinal, anural, seasonal, and diurnal variations. In comparison with COSMIC measurements of the year of 2012, the reconstructed model indicates a reasonable accuracy. In order to improve the topside model of International Reference Ionosphere (IRI), we attempted to adopt the scale height model in the Bent topside model by applying a scale factor q as an additional constraint. With the factor q functioning in the exponent profile of topside ionosphere, the IRI scale height should be forced equal to the precise COSMIC measurements. In this way, the IRI topside profile can be improved to get closer to the realistic density profiles. Internal quality check of this approach is carried out by comparing COSMIC realistic measurements and IRI with or without correction, respectively. In general, the initial IRI model overestimates the topside electron density to some extent, and with the correction introduced by COSMIC scale height model, the deviation of vertical total electron content (VTEC) between them is reduced. Furthermore, independent validation with Global Ionospheric Maps VTEC implies a reasonable improvement in the IRI VTEC with the topside model correction.

  10. Impact of Building Heights on 3d Urban Density Estimation from Spaceborne Stereo Imagery

    Science.gov (United States)

    Peng, Feifei; Gong, Jianya; Wang, Le; Wu, Huayi; Yang, Jiansi

    2016-06-01

    In urban planning and design applications, visualization of built up areas in three dimensions (3D) is critical for understanding building density, but the accurate building heights required for 3D density calculation are not always available. To solve this problem, spaceborne stereo imagery is often used to estimate building heights; however estimated building heights might include errors. These errors vary between local areas within a study area and related to the heights of the building themselves, distorting 3D density estimation. The impact of building height accuracy on 3D density estimation must be determined across and within a study area. In our research, accurate planar information from city authorities is used during 3D density estimation as reference data, to avoid the errors inherent to planar information extracted from remotely sensed imagery. Our experimental results show that underestimation of building heights is correlated to underestimation of the Floor Area Ratio (FAR). In local areas, experimental results show that land use blocks with low FAR values often have small errors due to small building height errors for low buildings in the blocks; and blocks with high FAR values often have large errors due to large building height errors for high buildings in the blocks. Our study reveals that the accuracy of 3D density estimated from spaceborne stereo imagery is correlated to heights of buildings in a scene; therefore building heights must be considered when spaceborne stereo imagery is used to estimate 3D density to improve precision.

  11. Density Effects on Plant Height Growth and Inequality in Sunflower Populations

    Institute of Scientific and Technical Information of China (English)

    Sa Xiao; Shu-Yan Chen; Lu-Qiang Zhao; Gang Wang

    2006-01-01

    Comparisons between competing and non-competing sunflower (Helianthus annuus L.) populations demonstrate pronounced effects of density on plant height growth, height-to-crown width ratio, and a population's height inequality. In the present study, non-destructive measurements of height and the projected crown area of sunflower plants were taken at seven times from emergence to fruit maturation in even-aged monospecific stands with initial densities of 1, 4, 16, and 64 plants/m2. The mean height of populations increased and then decreased with increasing population density; the height inequalities of uncrowded populations decreased during stand growth, whereas the height inequalities of crowded populations decreased first and then increased during stand development. The interindividual relationships between the relative height growth rate and height within uncrowded populations became significantly negative during population growth, whereas these relationships were negative first and then became positive during the development of crowded populations. In the uncrowded populations, the static interindividual relationship between height-to-crown width ratio and volume was positive, whereas for the crowded population these relationships became negative with increasing competition for light. The data suggest that the plastic responses of plant height and height-to-crown width ratio to light competition will become more intense with increasing competition intensity. The results of the present study argue strongly for the importance of size-dependent individual-level plastic responses due to size-asymmetric light competition in generating the variations in population height inequality.

  12. Martian thermosphere scale height from SPICAM dayglow measurements

    Science.gov (United States)

    Stiepen, A.; Gérard, J.-C.; Bougher, S.; Montmessin, F.

    2014-04-01

    We analyze the ultraviolet dayglow in the atmosphere of Mars through CO2+ and CO Cameron emissions. These emissions are accumulated on a large dataset of dayside grazing limb performed by the Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM) instrument on board the Mars Express spacecraft. The temperature of the Martian upper atmosphere can be retrieved from these limb emission profiles. We present discussion on the validity domain for such retrieval. We also show evidence for local (spatial and temporal) variability in the scale height of the atmosphere at the altitude of these emissions.

  13. Control of Carbon Nanotube Density and Tower Height in an Array

    Science.gov (United States)

    Delzeit, Lance D. (Inventor); Schipper, John F. (Inventor)

    2010-01-01

    A method for controlling density or tower height of carbon nanotube (CNT) arrays grown in spaced apart first and second regions on a substrate. CNTs having a first density range (or first tower height range) are grown in the first region using a first source temperature range for growth. Subsequently or simultaneously, CNTs having a second density range (or second tower height range), having an average density (or average tower height) in the second region different from the average density (or average tower height) for the first region, are grown in the second region, using supplemental localized hearing for the second region. Application for thermal dissipation and/or dissipation of electrical charge or voltage in an electronic device are discussed.

  14. Model of topside ionosphere scale height based on topside sounder data

    Science.gov (United States)

    Kutiev, I.; Marinov, P.; Watanabe, S.

    A new model of topside ionosphere scale height (TISH) is developed, based on the vertical electron density (Ne) profiles obtained from topside ionosondes. The model provides the vertical scale height as a function of month of the year, local time, geomagnetic latitude, longitude and solar flux F107. To define TISH, the O+ scale height above the peak of the F2 layer is assumed to be represented by the lowest gradient in the measured profile. Then a regression line is calculated over those Ne values of the measured profile at which the gradient is within 39% from the lowest. This 30% tolerance accounts for the increase of plasma temperature with altitude. The model data base contains 170,033 TISH values, extracted from individual N(h) profiles gathered between 1962 and 1978 by Aluoette and ISIS satellites. The data sample sufficiently all parameter's ranges. The model describes the vertical plasma scale height by a multivariable polynomial consisted from Chebishev's and trigonometric base functions, which is fitted to the data in the 5-dimensional space. The model TISH variations along the different parameters are presented. The model results are compared with IRI and other available models.

  15. Estimation of the Vertical Disk Scale Height Using Young Galactic Objects

    CERN Document Server

    Bobylev, V V

    2016-01-01

    We have collected literature data on young Galactic objects such as masers with VLBI-measured trigonometric parallaxes, OB associations, HII regions and Cepheids. We have recently established that vertical disk scale height is strongly influenced by the objects of the Local arm. In the present work we used samples that do not contain objects in this arm. Based on the model of a self-gravitating isothermal disk for the density distribution, we have found the following vertical disk scale heights: h=46+/-5 pc from 69 masers with trigonometric parallaxes, h=36+/-3 pc from 59 OB associations, h=35.6+/-2.7 pc from 147 HII regions, h=52.1+/-1.9 pc from 195 young Cepheids, and h=72.0+/-2.3 pc from 192 old Cepheids.

  16. The Flattened Dark Matter Halo of M31 as Deduced from the Observed HI Scale Heights

    CERN Document Server

    Banerjee, Arunima

    2008-01-01

    In this paper, we use the outer-galactic HI scale height data as well as the observed rotation curve as constraints to determine the halo density distribution of the Andromeda galaxy (M31). We model the galaxy as a gravitationally-coupled system of stars and gas, responding to the external force-field of a known Hernquist bulge and the dark matter halo, the density profile of the latter being characterized by four free parameters. The parameter space of the halo is optimized so as to match the observed HI thickness distribution as well as the rotation curve on an equal footing, unlike the previous studies of M31 which were based on rotation curves alone. We show that an oblate halo, with an isothermal density profile, provides the best fit to the observed data. This gives a central density of 0.011 M_sun /pc^3, a core radius of 21 kpc, and an axis ratio of 0.4. The main result from this work is the flattened dark matter halo for M31, which is required to match the outer galactic HI scale height data. Interest...

  17. Using scale heights derived from bottomside ionograms for modelling the IRI topside profile

    Directory of Open Access Journals (Sweden)

    B. W. Reinisch

    2004-01-01

    Full Text Available Groundbased ionograms measure the Chapman scale height HT at the F2-layer peak that is used to construct the topside profile. After a brief review of the topside model extrapolation technique, comparisons are presented between the modeled profiles with incoherent scatter radar and satellite measurements for the mid latitude and equatorial ionosphere. The total electron content TEC, derived from measurements on satellite beacon signals, is compared with the height-integrated profiles ITEC from the ionograms. Good agreement is found with the ISR profiles and with results using the low altitude TOPEX satellite. The TEC values derived from GPS signal analysis are systematically larger than ITEC. It is suggested to use HT , routinely measured by a large number of Digisondes around the globe, for the construction of the IRI topside electron density profile.

  18. CORRECTION TO HELMERT'S ORTHOMETRIC HEIGHT DUE TO ACTUAL LATERAL VARIATION OF TOPOGRAPHICAL DENSITY

    Directory of Open Access Journals (Sweden)

    Petr Vanícek

    2003-12-01

    Full Text Available Helmert (1890 used Poincaré-Prey's gravity gradient for the definition of the orthometric height. According to this approach the gravity value needed for the evaluation of the height is obtained from the observed gravity at the earth surface reduced to the mid-point between the earth surface and the geoid, considering that the gravity gradient is constant along the plumbline. Moreover, the mean topographical density is assumed to approximate the actual distribution of topographical density. The correction to Helmert's orthometric height due to the lateral variation of topographical density has been introduced by Vanícek et al. (1995. In this paper, some numerical aspects of this correction are investigated.

  19. Variations of topside ionospheric scale heights over Millstone Hill during the 30-day incoherent scatter radar experiment

    Directory of Open Access Journals (Sweden)

    L. Liu

    2007-10-01

    Full Text Available A 30-day incoherent scatter radar (ISR experiment was conducted at Millstone Hill (288.5° E, 42.6° N from 4 October to 4 November 2002. The altitude profiles of electron density Ne, ion and electron temperature (Ti and Te, and line-of-sight velocity during this experiment were processed to deduce the topside plasma scale height Hp, vertical scale height VSH, Chapman scale height Hm, ion velocity, and the relative altitude gradient of plasma temperature (dTp/dh/Tp, as well as the F2 layer electron density (NmF2 and height (hmF2. These data are analyzed to explore the variations of the ionosphere over Millstone Hill under geomagnetically quiet and disturbed conditions. Results show that ionospheric parameters generally follow their median behavior under geomagnetically quiet conditions, while the main feature of the scale heights, as well as other parameters, deviated significantly from their median behaviors under disturbed conditions. The enhanced variability of ionospheric scale heights during the storm-times suggests that the geomagnetic activity has a major impact on the behavior of ionospheric scale heights, as well as the shape of the topside electron density profiles. Over Millstone Hill, the diurnal behaviors of the median VSH and Hm are very similar to each other and are not so tightly correlated with that of the plasma scale height Hp or the plasma temperature. The present study confirms the sensitivity of the ionospheric scale heights over Millstone Hill to thermal structure and dynamics. The values of VSH/Hp tend to decrease as (dTp/dh/Tp becomes larger or the dynamic processes become enhanced.

  20. The shape of galaxy disks : How the scale height increases with galactocentric distance

    NARCIS (Netherlands)

    Grijs, R. de; Peletier, R. F.

    1997-01-01

    We present the results of a detailed study of vertical surface brightness profiles of edge-on disk galaxies. Although the exponential disk scale height is constant to first order approximation, we show that for the large majority of galaxies in our sample, the scale height increases with distance al

  1. Effects of Percent Tree Canopy Density and DEM Misregistration on SRTM/NED Vegetation Height Estimates

    Directory of Open Access Journals (Sweden)

    George Miliaresis

    2009-04-01

    Full Text Available The U.S National Elevation Dataset and the NLCD 2001 landcover data were used to test the correlation between SRTM elevation values and the height of evergreen forest vegetation in the Klamath Mountains of California.Vegetation height estimates (SRTM-NED are valid only for the two out of eight (N, NE, E, SE, S, SW, W, NW geographic directions, due to NED and SRTM grid data misregistration. Penetration depths of SRTM radar were found to linearly correlate to tree percent canopy density.

  2. Body mass index and body composition scaling to height in children and adolescent

    OpenAIRE

    Chung, Sochung

    2015-01-01

    Childhood obesity prevalence has been increased and known to be related to various diseases and mortality in adult and body mass index (BMI) has been widely used as a screening tool in children with obesity. It is important to understand what BMI is and its limitations. BMI is a measure of weight adjusted for height. Weight scales to height with a power of about 2, is the basis of BMI (weight/height2) as the scaling of body weight to height across adults provides powers rounded to 2. BMI has ...

  3. Mars thermospheric scale height: CO Cameron and CO2+ dayglow observations from Mars Express

    Science.gov (United States)

    Stiepen, A.; Gérard, J.-C.; Bougher, S.; Montmessin, F.; Hubert, B.; Bertaux, J.-L.

    2015-01-01

    The CO Cameron (170-270 nm) and CO2+ ultraviolet doublet (298 and 299 nm) emissions have been observed on the Mars dayside with Mars Express Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars (SPICAM) instrument in the limb viewing mode. These ultraviolet emissions ultimately arise from the excitation of the neutral atmosphere by solar extreme ultraviolet radiation. We analyze a wide dataset covering the years 2003-2013 to determine the scale height of the thermosphere and its variability. We show under which conditions the neutral thermospheric temperature is derived from the CO Cameron and CO2+ emission topside scale height of the limb profiles. We show that emission scale heights are highly variable, ranging from 8.4 to 21.8 km and analyze possible differences between CO Cameron and CO2+-derived scale heights. These large variations appear to dominate over the long-term control exerted by the solar flux reaching the top of the atmosphere during the SPICAM observing period when solar minimum to moderate conditions prevailed. Solar heating impacting the topside thermosphere scale height is apparently overwhelmed by other forcing processes (e.g. waves and tides) during this observing period. It also appears that the crustal residual magnetic field does not significantly influence the scale height of the thermosphere. Furthermore, our analysis suggests that local variations in the thermospheric scale height and associated temperature are equal to or larger than seasonal-latitudinal variability.

  4. Does the stellar distribution flare? A comparison of stellar scale heights with LAB H I data

    Energy Technology Data Exchange (ETDEWEB)

    Kalberla, P. M. W.; Kerp, J.; Dedes, L. [Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn (Germany); Haud, U., E-mail: pkalberla@astro.uni-bonn.de [Tartu Observatory, 61602 Tõravere (Estonia)

    2014-10-10

    The question of whether the stellar populations in the Milky Way take part in the flaring of scale heights as observed for the H I gas is a matter of debate. Standard mass models for the Milky Way assume a constant scale height for each of the different stellar distributions. However, there is mounting evidence that at least some of the stellar distributions reach, at large galactocentric distances, high altitudes, which are incompatible with a constant scale height. We discuss recent observational evidence for stellar flaring and compare it with H I data from the Leiden/Argentine/Bonn survey. Within the systemic and statistical uncertainties we find a good agreement between both.

  5. Does the Stellar Distribution Flare? A Comparison of Stellar Scale Heights with LAB H I Data

    Science.gov (United States)

    Kalberla, P. M. W.; Kerp, J.; Dedes, L.; Haud, U.

    2014-10-01

    The question of whether the stellar populations in the Milky Way take part in the flaring of scale heights as observed for the H I gas is a matter of debate. Standard mass models for the Milky Way assume a constant scale height for each of the different stellar distributions. However, there is mounting evidence that at least some of the stellar distributions reach, at large galactocentric distances, high altitudes, which are incompatible with a constant scale height. We discuss recent observational evidence for stellar flaring and compare it with H I data from the Leiden/Argentine/Bonn survey. Within the systemic and statistical uncertainties we find a good agreement between both.

  6. Does the stellar distribution flare? A comparison of stellar scale heights with LAB HI data

    CERN Document Server

    Kalberla, P M W; Dedes, L; Haud, U

    2014-01-01

    The question, whether the stellar populations in the Milky Way take part in flaring of the scale heights as observed for the HI gas is a matter of debate. Standard mass models for the Milky Way assume a constant scale height for each of the different stellar distributions. However, there is mounting evidence that at least some of the stellar distributions reach at large galactocentric distances high altitudes that are incompatible with a constant scale height. We discuss recent observational evidence for stellar flaring and compare it with HI data from the Leiden/Argentine/Bonn (LAB) survey. Within the systemic and statistical uncertainties we find a good agreement between both.

  7. Scale invariant density perturbations from cyclic cosmology

    Science.gov (United States)

    Frampton, Paul Howard

    2016-04-01

    It is shown how quantum fluctuations of the radiation during the contraction era of a comes back empty (CBE) cyclic cosmology can provide density fluctuations which re-enter the horizon during the subsequent expansion era and at lowest order are scale invariant, in a Harrison-Zel’dovich-Peebles sense. It is necessary to be consistent with observations of large scale structure.

  8. [Multi-wavelength spectral aerosol scale height in inshore in contrast with that in inland].

    Science.gov (United States)

    Han, Yong; Rao, Rui-Zhong; Wang, Ying-Jian

    2009-01-01

    In the present paper, based on the exponential attenuation of atmospheric aerosol concentration with height, so using continuous spectrum sun-photometer, forward scatter visibility sensor and hygrothermograph, the authors measured the atmosphere column optical characteristic and plane spectral extinction coefficient on earth on the base of two experiments at some edge of ocean at the same time, respectively, set up the calculative method of multi-wavelength spectral aerosol scale height. Firstly, the authors obtained atmospheric horizontal extinction coefficient with forward scattering visibility sensor, which subtracted molecular extinction coefficient, and could get aerosol extinction coefficient near ground; Then, selecting sea salt model, using OPAC software, the authors also could calculate the aerosol extinction coefficient under different humidity (0%, 50%, 70%, 80%, 90%, 95%, 98% and 99%) and different wavelength (400, 450, 500, 550, 600, 650, 700 and 750 nm), the aerosol extinction coefficient was detected by visibility sensor, using interpolation method, respectively; Finally, using the data of atmospheric columniation optical thickness detected by continuous spectral sun-photometer and subtracted molecular optical thickness corresponding wavelengths were accounted out by Modtran 4. 0. The authors obtained the characteristic of spectral aerosol scale height of visible light (wavelength is 400, 440, 532, 550 and 690 nm): with wavelength increments, and spectral aerosol scale height was found to decline neither in inland nor in inshore in China; Spectral aerosol scale height in winter is higher than in summer in southeast inshore; but spectral aerosol scale height in winter is smaller in summer than in inland.

  9. Multiconfiguration pair-density functional theory: barrier heights and main group and transition metal energetics.

    Science.gov (United States)

    Carlson, Rebecca K; Li Manni, Giovanni; Sonnenberger, Andrew L; Truhlar, Donald G; Gagliardi, Laura

    2015-01-13

    Kohn-Sham density functional theory, resting on the representation of the electronic density and kinetic energy by a single Slater determinant, has revolutionized chemistry, but for open-shell systems, the Kohn-Sham Slater determinant has the wrong symmetry properties as compared to an accurate wave function. We have recently proposed a theory, called multiconfiguration pair-density functional theory (MC-PDFT), in which the electronic kinetic energy and classical Coulomb energy are calculated from a multiconfiguration wave function with the correct symmetry properties, and the rest of the energy is calculated from a density functional, called the on-top density functional, that depends on the density and the on-top pair density calculated from this wave function. We also proposed a simple way to approximate the on-top density functional by translation of Kohn-Sham exchange-correlation functionals. The method is much less expensive than other post-SCF methods for calculating the dynamical correlation energy starting with a multiconfiguration self-consistent-field wave function as the reference wave function, and initial tests of the theory were quite encouraging. Here, we provide a broader test of the theory by applying it to bond energies of main-group molecules and transition metal complexes, barrier heights and reaction energies for diverse chemical reactions, proton affinities, and the water dimerization energy. Averaged over 56 data points, the mean unsigned error is 3.2 kcal/mol for MC-PDFT, as compared to 6.9 kcal/mol for Kohn-Sham theory with a comparable density functional. MC-PDFT is more accurate on average than complete active space second-order perturbation theory (CASPT2) for main-group small-molecule bond energies, alkyl bond dissociation energies, transition-metal-ligand bond energies, proton affinities, and the water dimerization energy.

  10. Relating urban scaling, fundamental allometry, and density scaling

    CERN Document Server

    Rybski, Diego

    2016-01-01

    We study the connection between urban scaling, fundamental allometry (between city population and city area), and per capita vs.\\ population density scaling. From simple analytical derivations we obtain the relation between the 3 involved exponents. We discuss particular cases and ranges of the exponents which we illustrate in a "phase diagram". As we show, the results are consistent with previous work.

  11. Small-scale open ocean currents have large effects on wind wave heights

    Science.gov (United States)

    Ardhuin, Fabrice; Gille, Sarah T.; Menemenlis, Dimitris; Rocha, Cesar B.; Rascle, Nicolas; Chapron, Bertrand; Gula, Jonathan; Molemaker, Jeroen

    2017-06-01

    Tidal currents and large-scale oceanic currents are known to modify ocean wave properties, causing extreme sea states that are a hazard to navigation. Recent advances in the understanding and modeling capability of open ocean currents have revealed the ubiquitous presence of eddies, fronts, and filaments at scales 10-100 km. Based on realistic numerical models, we show that these structures can be the main source of variability in significant wave heights at scales less than 200 km, including important variations down to 10 km. Model results are consistent with wave height variations along satellite altimeter tracks, resolved at scales larger than 50 km. The spectrum of significant wave heights is found to be of the order of 70>>2/>(g2>>2>) times the current spectrum, where >> is the spatially averaged significant wave height, >> is the energy-averaged period, and g is the gravity acceleration. This variability induced by currents has been largely overlooked in spite of its relevance for extreme wave heights and remote sensing.Plain Language SummaryWe show that the variations in currents at scales 10 to 100 km are the main source of variations in wave heights at the same scales. Our work uses a combination of realistic numerical models for currents and waves and data from the Jason-3 and SARAL/AltiKa satellites. This finding will be of interest for the investigation of extreme wave heights, remote sensing, and air-sea interactions. As an immediate application, the present results will help constrain the error budget of the up-coming satellite missions, in particular the Surface Water and Ocean Topography (SWOT) mission, and decide how the data will have to be processed to arrive at accurate sea level and wave measurements. It will also help in the analysis of wave measurements by the CFOSAT satellite.

  12. Electron Density Profile Data Contains Virtual Height/Frequency Pairs from a Profile or Profiles (Composite Months) of Ionograms

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Electron Density Profile, N(h), data set contains both individual profiles and composite months. The data consist of virtual height/frequency pairs from a...

  13. A parameterization of momentum roughness length and displacement height for a wide range of canopy densities

    Directory of Open Access Journals (Sweden)

    A. Verhoef

    1997-01-01

    Full Text Available Values of the momentum roughness length, z0, and displacement height, d, derived from wind profiles and momentum flux measurements, are selected from the literature for a variety of sparse canopies. These include savannah, tiger-bush and several row crops. A quality assessment of these data, conducted using criteria such as available fetch, height of wind speed measurement and homogeneity of the experimental site, reduced the initial total of fourteen sites to eight. These datapoints, combined with values carried forward from earlier studies on the parameterization of z0 and d, led to a maximum number of 16 and 24 datapoints available for d and z0, respectively. The data are compared with estimates of roughness length and displacement height as predicted from a detailed drag partition model, R92 (Raupach, 1992, and a simplified version of this model, R94 (Raupach, 1994. A key parameter in these models is the roughness density or frontal area index, λ. Both the comprehensive and the simplified model give accurate predictions of measured z0 and d values, but the optimal model coefficients are significantly different from the ones originally proposed in R92 and R94. The original model coefficients are based predominantly on measured aerodynamic parameters of relatively closed canopies and they were fitted `by eye'. In this paper, best-fit coefficients are found from a least squares minimization using the z0 and d values of selected good-quality data for sparse canopies and for the added, mainly closed canopies. According to a statistical analysis, based on the coefficient of determination (r2, the number of observations and the number of fitted model coefficients, the simplified model, R94, is deemed to be the most appropriate for future z0 and d predictions. A CR value of 0.35 and a cd1 value of about 20 are found to be appropriate for a large range of canopies varying in density from closed to very sparse. In this case, 99% of the total variance

  14. Combined oral contraceptives' influence on weight, body composition, height, and bone mineral density in girls younger than 18 years

    DEFF Research Database (Denmark)

    Warholm, Lina; Petersen, Kresten R; Ravn, Pernille

    2012-01-01

    Combined oral contraceptives (COCs) are increasingly used by adolescents. The aim of this review is to investigate the evidence regarding COCs' influence on weight, height and bone mineral density (BMD) in girls younger than 18 years.......Combined oral contraceptives (COCs) are increasingly used by adolescents. The aim of this review is to investigate the evidence regarding COCs' influence on weight, height and bone mineral density (BMD) in girls younger than 18 years....

  15. Forest stand height determination from low point density airborne laser scanning data in Roznava Forest enterprise zone (Slovakia

    Directory of Open Access Journals (Sweden)

    Smreček R

    2013-01-01

    Full Text Available The presented paper discusses the potential of low point density airborne laser scanning (ALS data for use in forestry management. Scanning was carried out in the Rožnava Forest enterprise zone, Slovakia, with a mean laser point density of 1 point per 3 m2. Data were processed in SCOP++ using the hierarchic robust filtering technique. Two DTMs were created from airborne laser scanning (ALS and contour data and one DSM was created using ALS data. For forest stand height, two normalised DSMs (nDSMs were created by subtraction of the DSM and DTM. The forest stand heights derived from these nDSMs and the application of maximum and mean zonal functions were compared with those contained in the current Forest Management Plan (FMP. The forest stand heights derived from these data and the application of maxima and mean zonal functions were compared with those contained in the current Forest management plan. The use of the mean function and the contour-derived DTM resulted in forest stand height being underestimated by approximately 3% for stands of densities 0.9 and 1.0, and overestimated by 6% for a stand density of 0.8. Overestimation was significantly greater for lower forest stand densities: 81% for a stand density of 0.0 and 37% for a density of 0.4, with other discrepancies ranging between 15 and 30%. Although low point density ALS should be used carefully in the determination of other forest stand parameters, this low-cost method makes it useful as a control tool for felling, measurement of disaster areas and the detection of gross errors in the FMP data. Through determination of forest stand height, tree felling in three forest stands was identified. Because of big differences between the determined forest stand height and the heights obtained from the FMP, tree felling was verified on orthoimages.

  16. Large scale spatio-temporal behaviour in surface growth. Scaling and dynamics of slow height variations in generalized two-dimensional Kuramoto-Sivashinsky equations

    Science.gov (United States)

    Juknevičius, Vaidas; Ruseckas, Julius; Armaitis, Jogundas

    2017-09-01

    This paper presents new findings concerning the dynamics of the slow height variations in surfaces produced by the two-dimensional isotropic Kuramoto-Sivashinsky equation with an additional nonlinear term. In addition to the disordered cellular patterns of specific size evident at small scales, slow height variations of scale-free character become increasingly evident when the system size is increased. This paper focuses on the parameter range in which the kinetic roughening with eventual saturation in surface roughness and coarseness is obtained, and the statistical and dynamical properties of surfaces in the long-time stationary regime are investigated. The resulting long-range scaling properties of the saturated surface roughness consistent with the power-law shape of the surface spectrum at small wave numbers are obtained in a wider parameter range than previously reported. The temporal properties of these long-range height variations are investigated by analysing the time series of surface roughness fluctuations. The resulting power-spectral densities can be expressed as a generalized Lorentzian whose cut-off frequency varies with system size. The dependence of this lower cut-off frequency on the smallest wave number connects spatial and temporal properties and gives new insight into the surface evolution on large scales.

  17. Effects of LiDAR point density, sampling size and height threshold on estimation accuracy of crop biophysical parameters.

    Science.gov (United States)

    Luo, Shezhou; Chen, Jing M; Wang, Cheng; Xi, Xiaohuan; Zeng, Hongcheng; Peng, Dailiang; Li, Dong

    2016-05-30

    Vegetation leaf area index (LAI), height, and aboveground biomass are key biophysical parameters. Corn is an important and globally distributed crop, and reliable estimations of these parameters are essential for corn yield forecasting, health monitoring and ecosystem modeling. Light Detection and Ranging (LiDAR) is considered an effective technology for estimating vegetation biophysical parameters. However, the estimation accuracies of these parameters are affected by multiple factors. In this study, we first estimated corn LAI, height and biomass (R2 = 0.80, 0.874 and 0.838, respectively) using the original LiDAR data (7.32 points/m2), and the results showed that LiDAR data could accurately estimate these biophysical parameters. Second, comprehensive research was conducted on the effects of LiDAR point density, sampling size and height threshold on the estimation accuracy of LAI, height and biomass. Our findings indicated that LiDAR point density had an important effect on the estimation accuracy for vegetation biophysical parameters, however, high point density did not always produce highly accurate estimates, and reduced point density could deliver reasonable estimation results. Furthermore, the results showed that sampling size and height threshold were additional key factors that affect the estimation accuracy of biophysical parameters. Therefore, the optimal sampling size and the height threshold should be determined to improve the estimation accuracy of biophysical parameters. Our results also implied that a higher LiDAR point density, larger sampling size and height threshold were required to obtain accurate corn LAI estimation when compared with height and biomass estimations. In general, our results provide valuable guidance for LiDAR data acquisition and estimation of vegetation biophysical parameters using LiDAR data.

  18. Global characteristics of the upper transition height derived from the topside Alouette/ISIS topside sounder electron density profiles, the Formosat-3/COSMIC density profiles and the IRI ion composition model

    Science.gov (United States)

    Truhlik, Vladimir; Triskova, Ludmila; Benson, Robert; Bilitza, Dieter; Chu, Philip; Richards, Phil G.; Wang, Yongli

    The upper transition height (Ht) (the altitude of the transition from heavy atomic ions to light ions or in the simplest form the transition from O+ to H+) is an important parameter, representing the boundary between the ionosphere and the plasmasphere. Ht is very sensitive to various geophysical parameters, like solar and magnetic activity and strongly depends on latitude and local time. There were numerous studies of this parameter in past decades. In spite of these efforts, no model satisfactorily represents this parameter so far. Moreover, surprising evidence of very low transition heights during the last prolonged solar minimum, of a level never obtained before, have been reported. We investigate the upper transition height on the global scale. We made progress in processing large data sets of Ht deduced from the Alouette/ISIS topside sounder and from the Formosat-3/COSMIC vertical electron-density profiles Ne(h) using the theoretical Global Plasma Ionosphere Density (GPID) model (Webb and Essex, 2004) and a revised non-linear function describing the scale height vs. altitude (Titheridge, 1976) to fit the vertical density profiles to the observed profiles and to determine the upper transition height. Since both methods require the plasma temperatures and their gradients as input, these are calculated using the IRI2012 model. Both methods are verified using a large amount of electron and ion density profiles simulated by the FLIP theoretical model and their accuracy is discussed. We compare the results from Alouette/ISIS and Formosat-3/COSMIC and present a global distribution of the calculated Ht and its dependence on geophysical parameters. Finally we compare it with Ht calculated using the IRI ion composition model. Titheridge, J.E., 1976. Ion Transition Heights from Topside Electron-Density Profiles. Planetary and Space Science 24 (3), 229-245. Webb, P.A., Essex, E.A., 2004. A dynamic global model of the plasmasphere. Journal of Atmospheric and Solar

  19. Scaled density functional theory correlation functionals.

    Science.gov (United States)

    Ghouri, Mohammed M; Singh, Saurabh; Ramachandran, B

    2007-10-18

    We show that a simple one-parameter scaling of the dynamical correlation energy estimated by the density functional theory (DFT) correlation functionals helps increase the overall accuracy for several local and nonlocal functionals. The approach taken here has been described as the "scaled dynamical correlation" (SDC) method [Ramachandran, J. Phys. Chem. A 2006, 110, 396], and its justification is the same as that of the scaled external correlation (SEC) method of Brown and Truhlar. We examine five local and five nonlocal (hybrid) DFT functionals, the latter group including three functionals developed specifically for kinetics by the Truhlar group. The optimum scale factors are obtained by use of a set of 98 data values consisting of molecules, ions, and transition states. The optimum scale factors, found with a linear regression relationship, are found to differ from unity with a high degree of correlation in nearly every case, indicating that the deviation of calculated results from the experimental values are systematic and proportional to the dynamic correlation energy. As a consequence, the SDC scaling of dynamical correlation decreases the mean errors (signed and unsigned) by significant amounts in an overwhelming majority of cases. These results indicate that there are gains to be realized from further parametrization of several popular exchange-correlation functionals.

  20. Statistical characteristics of the polar ionospheric scale height around the peak height of F2 layer with observations of the ESR radar: Disturbed days

    Science.gov (United States)

    Qiao, Zheng; Yuan, Zhigang; Huang, Shiyong; Wang, Dedong

    2017-10-01

    In this paper, based on observations of the European Incoherent Scatter Svalbard Radar (ESR) between 1997 and 2008, we analyzed variations of HmF2, the ionospheric scale height around the peak height of F2 layer (hmF2) at high latitude with geomagnetic activities, as well as variations of the HmF2 with the local time (LT), season and solar activity under disturbed conditions (2 < Kp ≤ 5). We found that the HmF2 shows a significant increment with enhancements of geomagnetic activities. In addition, based on a linear regression, the correlation and fitting coefficients are shown, which quantitatively describe the correlations between polar HmF2 and geomagnetic activity index Kp. The HmF2 shows a diurnal variation with a maximum early in the morning and a minimum around noon in disturbed days (2 < Kp ≤ 5), which is more complex in comparison with that in quiet days. However, in summer and autumn, the HmF2 in disturbed days shows a bulge during 06:00-11:00 LT instead of the continuous decline under quiet condition. We consider that the ESR was under the cusp region during the period so that the bulge might be related to the high-energy particles precipitating into the ionosphere resulting in changes of the electron density profile. The HmF2 has the highest seasonal magnitude in summer and the lowest seasonal magnitude in winter generally. The seasonal magnitude of the HmF2 in autumn is lower than that in spring and larger than that in winter under low solar activity, while the HmF2 shows the same seasonal variations in spring and autumn under moderate and high solar activities.

  1. Controlling the ripple density and heights: a new way to improve the electrical performance of CVD-grown graphene

    Science.gov (United States)

    Park, Won-Hwa; Jo, Insu; Hong, Byung Hee; Cheong, Hyeonsik

    2016-05-01

    We report a new way to enhance the electrical performances of large area CVD-grown graphene through controlling the ripple density and heights after transfer onto SiO2/Si substrates by employing different cooling rates during fabrication. We find that graphene films prepared with a high cooling rate have reduced ripple density and heights and improved electrical characteristics such as higher electron/hole mobilities as well as reduced sheet resistance. The corresponding Raman analysis also shows a significant decrease of the defects when a higher cooling rate is employed. We suggest a model that explains the improved morphology of the graphene film obtained with higher cooling rates. From these points of view, we can suggest a new pathway toward a relatively lower density and heights of ripples in order to reduce the flexural phonon-electron scattering effect, leading to higher lateral carrier mobilities.We report a new way to enhance the electrical performances of large area CVD-grown graphene through controlling the ripple density and heights after transfer onto SiO2/Si substrates by employing different cooling rates during fabrication. We find that graphene films prepared with a high cooling rate have reduced ripple density and heights and improved electrical characteristics such as higher electron/hole mobilities as well as reduced sheet resistance. The corresponding Raman analysis also shows a significant decrease of the defects when a higher cooling rate is employed. We suggest a model that explains the improved morphology of the graphene film obtained with higher cooling rates. From these points of view, we can suggest a new pathway toward a relatively lower density and heights of ripples in order to reduce the flexural phonon-electron scattering effect, leading to higher lateral carrier mobilities. Electronic supplementary information (ESI) available: Reproducible data set. See DOI: 10.1039/c6nr00706f

  2. Scaling of human body mass with height: the Body Mass Index revisited

    CERN Document Server

    MacKay, N J

    2009-01-01

    We adapt a biomechanical argument of Rashevsky, which places limits on the stress experienced by a torso supported by the legs, to deduce that body mass $m$ of growing children should scale as the $p$th power of height $h$ with $7/3scale as $h^q$ with $q$ near the lower end of $2/3\\leq q \\leq 1$. Data from Hong Kong and British children are consistent with these hypotheses.

  3. GROUND FILTERING LiDAR DATA BASED ON MULTI-SCALE ANALYSIS OF HEIGHT DIFFERENCE THRESHOLD

    Directory of Open Access Journals (Sweden)

    P. Rashidi

    2017-09-01

    Full Text Available Separating point clouds into ground and non-ground points is a necessary step to generate digital terrain model (DTM from LiDAR dataset. In this research, a new method based on multi-scale analysis of height difference threshold is proposed for ground filtering of LiDAR data. The proposed method utilizes three windows with different sizes in small, average and large to cover the entire LiDAR point clouds, then with a height difference threshold, point clouds can be separated to ground and non-ground in each local window. Meanwhile, the best threshold values for size of windows are considered based on physical characteristics of the ground surface and size of objects. Also, the minimum of height of object in each window selected as height difference threshold. In order to evaluate the performance of the proposed algorithm, two datasets in rural and urban area were applied. The overall accuracy in rural and urban area was 96.06% and 94.88% respectively. These results of the filtering showed that the proposed method can successfully filters non-ground points from LiDAR point clouds despite of the data area.

  4. Wintertime connections between extreme wind patterns in Spain and large-scale geopotential height field

    Science.gov (United States)

    Pascual, A.; Martín, M. L.; Valero, F.; Luna, M. Y.; Morata, A.

    2013-03-01

    The present study is focused on the study of the variability and the most significant wind speed patterns in Spain during the winter season analyzing as well connections between the wind speed field and the geopotential height at 1000 hPa over an Atlantic area. The daily wind speed variability is investigated by means of principal components using wind speed observations. Five main modes of variation, accounting 66% of the variance of the original data, have been identified, highlighting their differences in the Spanish wind speed behavior. Connections between the wind speeds and the large-scale atmospheric field were underlined by means of composite maps. Composite maps were built up to give an averaged atmospheric circulation associated with extreme wind speed variability in Spain. Moreover, the principal component analysis was also applied to the geopotential heights, providing relationships between the large-scale atmospheric modes and the observational local wind speeds. Such relationships are shown in terms of the cumulated frequency values of wind speed associated with the extreme scores of the obtained large-scale atmospheric modes, showing those large-scale atmospheric patterns more dominant in the wind field in Spain.

  5. A predictive nondestructive model for the covariation of tree height, diameter, and stem volume scaling relationships

    Science.gov (United States)

    Zhang, Zhongrui; Zhong, Quanlin; Niklas, Karl J.; Cai, Liang; Yang, Yusheng; Cheng, Dongliang

    2016-08-01

    Metabolic scaling theory (MST) posits that the scaling exponents among plant height H, diameter D, and biomass M will covary across phyletically diverse species. However, the relationships between scaling exponents and normalization constants remain unclear. Therefore, we developed a predictive model for the covariation of H, D, and stem volume V scaling relationships and used data from Chinese fir (Cunninghamia lanceolata) in Jiangxi province, China to test it. As predicted by the model and supported by the data, normalization constants are positively correlated with their associated scaling exponents for D vs. V and H vs. V, whereas normalization constants are negatively correlated with the scaling exponents of H vs. D. The prediction model also yielded reliable estimations of V (mean absolute percentage error = 10.5 ± 0.32 SE across 12 model calibrated sites). These results (1) support a totally new covariation scaling model, (2) indicate that differences in stem volume scaling relationships at the intra-specific level are driven by anatomical or ecophysiological responses to site quality and/or management practices, and (3) provide an accurate non-destructive method for predicting Chinese fir stem volume.

  6. A predictive nondestructive model for the covariation of tree height, diameter, and stem volume scaling relationships.

    Science.gov (United States)

    Zhang, Zhongrui; Zhong, Quanlin; Niklas, Karl J; Cai, Liang; Yang, Yusheng; Cheng, Dongliang

    2016-08-24

    Metabolic scaling theory (MST) posits that the scaling exponents among plant height H, diameter D, and biomass M will covary across phyletically diverse species. However, the relationships between scaling exponents and normalization constants remain unclear. Therefore, we developed a predictive model for the covariation of H, D, and stem volume V scaling relationships and used data from Chinese fir (Cunninghamia lanceolata) in Jiangxi province, China to test it. As predicted by the model and supported by the data, normalization constants are positively correlated with their associated scaling exponents for D vs. V and H vs. V, whereas normalization constants are negatively correlated with the scaling exponents of H vs. D. The prediction model also yielded reliable estimations of V (mean absolute percentage error = 10.5 ± 0.32 SE across 12 model calibrated sites). These results (1) support a totally new covariation scaling model, (2) indicate that differences in stem volume scaling relationships at the intra-specific level are driven by anatomical or ecophysiological responses to site quality and/or management practices, and (3) provide an accurate non-destructive method for predicting Chinese fir stem volume.

  7. A RESEARCH ON THE EFFECTS OF TEA, SMOKING AND SODA ON WEIGHT HEIGHT AND BONE MINARAL DENSITY (BMD OF ATHLETS

    Directory of Open Access Journals (Sweden)

    H. Bayram TEMUR

    2011-12-01

    Full Text Available In this study, it was aimed to investigate whether incomes of the family, tea, smoke and soda have effect on the weight, height and bone mineral density of athletes. 80 athletes whose average age was 16.62- 0.92 were included. BMD of the lumbar spine (L1-L4 of the subjects was measured by Dual energy X-ray Absorbtiometry (DEXA (g/cm. Values of the family income and the daily consumption of tea, smoke and soda in the families of the athletes were researched. Values of weight and height of the athletes were also determined. In the analyses of the data obtained in the study, SPSS 15.0 package program was used. The results of this study demonstrated that there is no relation between the values of smoke, tea and soda with the values of weight, height and BMD. However, despite the lack of a relationship between the BMD values and the family income level, significant correlation was obtained between the BMD values with the height values (p≤0.01 and the weight values (p≤0.05. Consequently it was determined that tea, smoke and soda do not have effects on weight, height and BMD. Hence, it is thought that the lack of effect of smoking on weight, height and BMD could be due to the less daily smoking (1.67-0.79 and less smoking average in the subjects (26.3%.

  8. Height and bone mineral density are associated with naevus count supporting the importance of growth in melanoma susceptibility.

    Directory of Open Access Journals (Sweden)

    Simone Ribero

    Full Text Available Naevus count is the strongest risk factor for melanoma. Body Mass Index (BMI has been linked to melanoma risk. In this study, we investigate the link between naevus count and height, weight and bone mineral density (BMD in the TwinsUK cohort (N = 2119. In addition we adjusted for leucocyte telomere length (LTL as LTL is linked to both BMD and naevus count. Naevus count was positively associated with height (p = 0.001 but not with weight (p = 0.187 despite adjusting for age and twin relatedness. This suggests that the previously reported melanoma association with BMI may be explained by height alone. Further adjustment for LTL did not affect the significance of the association between height and naevus count so LTL does not fully explain these results. BMD was associated with naevus count at the spine (coeff 18.9, p = 0.01, hip (coeff = 18.9, p = 0.03 and forearm (coeff = 32.7, p = 0.06 despite adjusting for age, twin relatedness, weight, height and LTL. This large study in healthy individuals shows that growth via height, probably in early life, and bone mass are risk factors for melanoma via increased naevus count. The link between these two phenotypes may possibly be explained by telomere biology, differentiation genes from the neural crests but also other yet unknown factors which may influence both bones and melanocytes biology.

  9. Height bias and scale effect induced by antenna gravitational deformations in geodetic VLBI data analysis

    Science.gov (United States)

    Sarti, Pierguido; Abbondanza, Claudio; Petrov, Leonid; Negusini, Monia

    2011-01-01

    The impact of signal path variations (SPVs) caused by antenna gravitational deformations on geodetic very long baseline interferometry (VLBI) results is evaluated for the first time. Elevation-dependent models of SPV for Medicina and Noto (Italy) telescopes were derived from a combination of terrestrial surveying methods to account for gravitational deformations. After applying these models in geodetic VLBI data analysis, estimates of the antenna reference point positions are shifted upward by 8.9 and 6.7 mm, respectively. The impact on other parameters is negligible. To simulate the impact of antenna gravitational deformations on the entire VLBI network, lacking measurements for other telescopes, we rescaled the SPV models of Medicina and Noto for other antennas according to their size. The effects of the simulations are changes in VLBI heights in the range [-3, 73] mm and a net scale increase of 0.3-0.8 ppb. The height bias is larger than random errors of VLBI position estimates, implying the possibility of significant scale distortions related to antenna gravitational deformations. This demonstrates the need to precisely measure gravitational deformations of other VLBI telescopes, to derive their precise SPV models and to apply them in routine geodetic data analysis.

  10. Birth weight, childhood body mass index, and height in relation to mammographic density and breast cancer

    DEFF Research Database (Denmark)

    Andersen, Zorana Jovanovic; Baker, Jennifer Lyn; Bihrmann, Kristine

    2014-01-01

    High breast density, a strong predictor of breast cancer may be determined early in life. Childhood anthropometric factors have been related to breast cancer and breast density, but rarely simultaneously. We examined whether mammographic density (MD) mediates an association of birth weight...

  11. Long-term analysis between radio occultation and ionosonde peak electron density and height during geomagnetic storms

    Science.gov (United States)

    Habarulema, John Bosco; Carelse, Suné Arlene

    2016-05-01

    For the first time, a long-term comparative analysis of radio occultation (RO) maximum electron density and peak height of the F2 layer (NmF2 and hmF2) with ionosonde data is presented during geomagnetic storm periods. Using the optimum spatial resolution of 4.5° × 4.5° in both latitude and longitude space over Grahamstown, GR13L(33.3°S, 26.5°E), South Africa, RO NmF2 and hmF2 (from CHAMP and COSMIC/FORMOSAT-3) are directly compared to ionosonde values within 15 min of ionosonde observational data from 2003 to end of May 2015. This study provides for the first time the deviation of RO data from ionosonde data on a long-term scale during disturbed conditions in a midlatitude region. We have found that maximum deviations between RO and ionosonde hmF2/NmF2 occur during the high solar activity periods. For some storms, deviations between RO and ionosonde hmF2 can reach values just over 30 km and 85 km during 2005-2010 and 2011-2015, respectively. Overall, statistical results show that hmF2 and NmF2 from these independent data sets agree to within ˜9% and 21% (1 standard deviation, 1σ) from 2003 to 2015. While the deviation can be large during some storm events, statistically and based on ionosonde data, RO F2 peak parameters in midlatitudes are not degraded significantly during disturbed conditions and can therefore be reliably used to study ionospheric dynamics during extreme space weather events.

  12. Allometric Scaling and Resource Limitations Model of Tree Heights: Part 3. Model Optimization and Testing over Continental China

    Directory of Open Access Journals (Sweden)

    Xiliang Ni

    2014-04-01

    Full Text Available The ultimate goal of our multi-article series is to demonstrate the Allometric Scaling and Resource Limitation (ASRL approach for mapping tree heights and biomass. This third article tests the feasibility of the optimized ASRL model over China at both site (14 meteorological stations and continental scales. Tree heights from the Geoscience Laser Altimeter System (GLAS waveform data are used for the model optimizations. Three selected ASRL parameters (area of single leaf, α; exponent for canopy radius, η; and root absorption efficiency, γ are iteratively adjusted to minimize differences between the references and predicted tree heights. Key climatic variables (e.g., temperature, precipitation, and solar radiation are needed for the model simulations. We also exploit the independent GLAS and in situ tree heights to examine the model performance. The predicted tree heights at the site scale are evaluated against the GLAS tree heights using a two-fold cross validation (RMSE = 1.72 m; R2 = 0.97 and bootstrapping (RMSE = 4.39 m; R2 = 0.81. The modeled tree heights at the continental scale (1 km spatial resolution are compared to both GLAS (RMSE = 6.63 m; R2 = 0.63 and in situ (RMSE = 6.70 m; R2 = 0.52 measurements. Further, inter-comparisons against the existing satellite-based forest height maps have resulted in a moderate degree of agreements. Our results show that the optimized ASRL model is capable of satisfactorily retrieving tree heights over continental China at both scales. Subsequent studies will focus on the estimation of woody biomass after alleviating the discussed limitations.

  13. Height biases and scale variations in VLBI networks due to antenna gravitational deformations

    Science.gov (United States)

    Abbondanza, Claudio; Sarti, Pierguido; Petrov, Leonid; Negusini, Monia

    2010-05-01

    The impact of signal path variations (SPVs) caused by antenna gravity deformations on geodetic VLBI results is evaluated for the first time. Elevation-dependent models of SPV for Medicina and Noto (Italy) telescopes were derived from a combination of terrestrial surveying methods to account for gravitational deformations. After applying these models, estimates of the antenna reference point (ARP) positions are shifted upward by 8.9 mm and 6.7 mm, respectively. The impact on other parameters is negligible. To infer the impact of antenna gravity deformations on the entire VLBI network, lacking measurements for other telescopes, we rescaled the SPV models of Medicina and Noto for other antennas according to their size. The effects are changes in VLBI heights in the range [-3,73] mm and a significant net scale increase of 0.3 - 0.8 ppb. This demonstrates the need to include SPV models in routine VLBI data analysis.

  14. Wind-invariant saltation heights imply linear scaling of aeolian saltation flux with shear stress.

    Science.gov (United States)

    Martin, Raleigh L; Kok, Jasper F

    2017-06-01

    Wind-driven sand transport generates atmospheric dust, forms dunes, and sculpts landscapes. However, it remains unclear how the flux of particles in aeolian saltation-the wind-driven transport of sand in hopping trajectories-scales with wind speed, largely because models do not agree on how particle speeds and trajectories change with wind shear velocity. We present comprehensive measurements, from three new field sites and three published studies, showing that characteristic saltation layer heights remain approximately constant with shear velocity, in agreement with recent wind tunnel studies. These results support the assumption of constant particle speeds in recent models predicting linear scaling of saltation flux with shear stress. In contrast, our results refute widely used older models that assume that particle speed increases with shear velocity, thereby predicting nonlinear 3/2 stress-flux scaling. This conclusion is further supported by direct field measurements of saltation flux versus shear stress. Our results thus argue for adoption of linear saltation flux laws and constant saltation trajectories for modeling saltation-driven aeolian processes on Earth, Mars, and other planetary surfaces.

  15. Kinetic Scale Density Fluctuations in the Solar Wind

    CERN Document Server

    Chen, C H K; Bonnell, J W; Mozer, F S; Klein, K G; Bale, S D

    2013-01-01

    We motivate the importance of studying kinetic scale turbulence for understanding the macroscopic properties of the heliosphere, such as the heating of the solar wind. We then discuss the technique by which kinetic scale density fluctuations can be measured using the spacecraft potential, including a calculation of the timescale for the spacecraft potential to react to the density changes. Finally, we compare the shape of the density spectrum at ion scales to theoretical predictions based on a cascade model for kinetic turbulence. We conclude that the shape of the spectrum, including the ion scale flattening, can be captured by the sum of passive density fluctuations at large scales and kinetic Alfven wave turbulence at small scales.

  16. An Improved Model for Operational Specification of the Electron Density Structure up to Geosynchronous Heights

    Science.gov (United States)

    2010-07-01

    tracking of spacecraft as part of space surveillance programmes; the use of space-based synthetic aperture radars (SAR) to carry out remote sensing of...Profiler (TSMP) and the TSMP-assisted Digisonde (TaD) model b) To validate the results using ISR and topside electron density profiles, GNSS TEC and...derived from ground-based GNSS receivers ............................ 20  2.3 Comparison with data from Malvern ISR

  17. The formation heights of coronal shocks from 2D density and Alfv\\'en speed maps

    CERN Document Server

    Zucca, Pietro; Bloomfield, D Shaun; Gallagher, Peter T

    2014-01-01

    Super-Alfv\\'enic shock waves associated with coronal mass ejections (CMEs) can produce radio emission known as Type II bursts. In the absence of direct imaging, accurate estimates of coronal electron densities, magnetic field strengths and Alfv\\'en speeds are required in order to calculate the kinematics of shocks. To date, 1D radial models have been used, but these are not appropriate for shocks propagating in non-radial directions. Here, we study a coronal shock wave associated with a CME and Type II radio burst using 2D electron density and Alfv\\'en speed maps to determine the locations that shocks are excited as the CME expands through the corona. Coronal density maps were obtained from emission measures derived from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory ($SDO$) and polarized brightness measurements from the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory ($SOHO$). Alfv\\'en speed maps were calculated using these dens...

  18. Height and weight are correlated with lumbar spinal bone mineral contents and densities in Chinese adolescents with early ankylosing spondylitis

    Institute of Scientific and Technical Information of China (English)

    MA Xing; HU Yun-yu; MA Xiang-dong; WANG Quan-ping; LI Xiao-juan; LU Rong; WANG Jun; XU Xin-zhi

    2004-01-01

    Objective: To explore the possible factors influencing lumbar spinal bone mineral contents and bone mineral densities in Chinese adolescents with early ankylosing spondylitis(AS). Methods: Thirty-one male Chinese adolescent outpatients with early AS were included and compared with 31 age-matched male controls. Age (year), height (cm), total body weight (kg) together with body mass index (BMI, kg/m2 ) of all subjects and disease duration (month), BASMI,BASFI, BASDAI, SASSS as well as ESR (mm/h) of AS patients were obtained. Lumbar2-4 bone mineral content (L2-4BMC, g) and lumbar2-4 areal bone mineral density (L2-4 BMD, g/cm2 ) were evaluated using dual-energy X-ray absorptiometry (DEXA) with Lunar DPX-IQ device and lumbar2-4 volumetric bone mineral apparent density (L2-4 BMAD, g/cm3 )was subsequently calculated. Correlation and multiple regression analyses were performed. Results: Compared with 31 agematched male controls, AS patients had significantly lower L2-4 BMD [ (0. 984 ± 0.142) g/cm2 vs ( 1.055 ± 0. 137) g/cm2,P = 0.049 ] and L2- 4 BMAD [ (0. 1527 ± 0. 0173) g/cm3 vs (0. 1630 ± 0. 0195) g/cm3, P = 0. 032 ]. In AS patients,multiple regression analysis identified that only the factor of height was significantly correlated with L2- 4 BMC ( R = 0. 673,P = 0.000) and the factor of weight had predominant influences on L2-4 BMD ( R = 0. 620, P = 0. 000) as well as L2-4BMAD (R=0.510, P = 0.003). Conclusion: The young patients with early AS had marked reduction in lumbar spine bone mineral densities, which indicated an important primary event leading to osteoporosis. Positive effects of height and weight on lumbar spine bone mass and densities could expectantly make favorable contributions to early prevention of AS associated bone loss and subsequent osteoporosis.

  19. Determining the solar-flare photospheric scale height from SMM gamma-ray measurements

    Science.gov (United States)

    Lingenfelter, Richard E.

    1991-01-01

    A connected series of Monte Carlo programs was developed to make systematic calculations of the energy, temporal and angular dependences of the gamma-ray line and neutron emission resulting from such accelerated ion interactions. Comparing the results of these calculations with the Solar Maximum Mission/Gamma Ray Spectrometer (SMM/GRS) measurements of gamma-ray line and neutron fluxes, the total number and energy spectrum of the flare-accelerated ions trapped on magnetic loops at the Sun were determined and the angular distribution, pitch angle scattering, and mirroring of the ions on loop fields were constrained. Comparing the calculations with measurements of the time dependence of the neutron capture line emission, a determination of the He-3/H ratio in the photosphere was also made. The diagnostic capabilities of the SMM/GRS measurements were extended by developing a new technique to directly determine the effective photospheric scale height in solar flares from the neutron capture gamma-ray line measurements, and critically test current atmospheric models in the flare region.

  20. Modelling of the electron density height profiles in the mid-latitude ionospheric D-region

    Directory of Open Access Journals (Sweden)

    P. Y. Mukhtarov

    1996-06-01

    Full Text Available A new mid-latitude D-region (50-105 km model of the electron density is presented obtained on the basis of a full wave theory and by a trial-and-error inversion method. Daytime (at different solar zenith angles absorption measurements by A3-technique made in Bulgaria yielded data with the aid of which the seasonal and diurnal courses of the Ne(h-profiles were derived. Special attention is drawn to the event diurnal asymmetry, or uneven formation of the ionosphere as a function of insulation. The latter is probably connected with the influence of the diurnal fluctuations in the local temperature on the chemistry involved in the electron loss rate, as well as the diurnal variations of the main ionizing agent (NO in the D-region. That is why the Ne(h-profiles in the midlatitude D-region are modelled separately for morning and afternoon hours.

  1. Disturbed time variations in the scale height at the F2 layer peak over 3 European stations

    Science.gov (United States)

    Estela Mosert, Marta; Buresova, Dalia; Magdaleno, Sergio; Altadill, David; de La Morena, Benito; Gerardo Ezquer, Rodolfo; Cabrera, Miguel Angel

    This paper examines the variations of the scale height at the F2 layer (Hm) for disturbed conditions in the mid-latitude ionosphere. The data base includes Hm values derived from ionograms recorded by digisondes located at: Pruhonice (50.0N, 15.0E), Ebro (40.4N, 0.3E) and El Arenosillo (37.1N, 353.3E). The data covers disturbed periods during the years 2000 and 2001.The behavior of other parameters derived from the electron density profiles such as the thickness parameter B0,and the ionospheric slab thickness are also analyzed (EST). As a measure of the ionospheric disturbance during the storms the relative deviations of the param-eters from the corresponding monthly median values have been calculated. All the parameters present changes during the storms. In general, increases during the main phase and first stage of the recovery phase are observed. The relative deviations of Hm, EST and B0 present similar temporal behavior

  2. Allometric Scaling and Resource Limitations Model of Tree Heights: Part 1. Model Optimization and Testing over Continental USA

    Directory of Open Access Journals (Sweden)

    Ramakrishna R. Nemani

    2013-01-01

    Full Text Available A methodology to generate spatially continuous fields of tree heights with an optimized Allometric Scaling and Resource Limitations (ASRL model is reported in this first of a multi-part series of articles. Model optimization is performed with the Geoscience Laser Altimeter System (GLAS waveform data. This methodology is demonstrated by mapping tree heights over forested lands in the continental USA (CONUS at 1 km spatial resolution. The study area is divided into 841 eco-climatic zones based on three forest types, annual total precipitation classes (30 mm intervals and annual average temperature classes (2 °C intervals. Three model parameters (area of single leaf, α, exponent for canopy radius, η, and root absorption efficiency, γ were selected for optimization, that is, to minimize the difference between actual and potential tree heights in each of the eco-climatic zones over the CONUS. Tree heights predicted by the optimized model were evaluated against GLAS heights using a two-fold cross validation approach (R2 = 0.59; RMSE = 3.31 m. Comparison at the pixel level between GLAS heights (mean = 30.6 m; standard deviation = 10.7 and model predictions (mean = 30.8 m; std. = 8.4 were also performed. Further, the model predictions were compared to existing satellite-based forest height maps. The optimized ASRL model satisfactorily reproduced the pattern of tree heights over the CONUS. Subsequent articles in this series will document further improvements with the ultimate goal of mapping tree heights and forest biomass globally.

  3. Scaling Evolution of Universal Dark-Matter Halo Density Profiles

    CERN Document Server

    Raig, A; Salvador-Solé, E

    1998-01-01

    Dark-matter halos show a universal density profile with a scaling such that less massive systems are typically denser. This mass-density relation is well described by a proportionality between the characteristic density of halos and the mean cosmic density at halo formation time. It has recently been shown that this proportionality could be the result of the following simple evolutionary picture. Halos form in major mergers with essentially the same, cosmogony-dependent, dimensionless profile, and then grow inside-outside, as a consequence of accretion. Here we verify the consistency of this picture and show that it predicts the correct zero point of the mass-density relation.

  4. Large scale radial stability density of Hill's equation

    NARCIS (Netherlands)

    Broer, Henk; Levi, Mark; Simo, Carles

    2013-01-01

    This paper deals with large scale aspects of Hill's equation (sic) + (a + bp(t)) x = 0, where p is periodic with a fixed period. In particular, the interest is the asymptotic radial density of the stability domain in the (a, b)-plane. It turns out that this density changes discontinuously in a certa

  5. Matter composition at high density by effective scaled lagrangian

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, Chang Ho; Min, Dong Pil [Dept. of Physics, Seoul National Univ., Seoul (Korea, Republic of)

    1998-06-01

    We investigate the matter composition at around the neutron star densities with a model lagrangian satisfying Brown-Rho scaling law. We calculate the neutron star properties such as maximum mass, radius, hyperon compositions and central density. We compare our results with those of Walecka model. (orig.)

  6. Large Scale Density Estimation of Blue and Fin Whales (LSD)

    Science.gov (United States)

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Large Scale Density Estimation of Blue and Fin Whales ...sensors, or both. The goal of this research is to develop and implement a new method for estimating blue and fin whale density that is effective over...develop and implement a density estimation methodology for quantifying blue and fin whale abundance from passive acoustic data recorded on sparse

  7. Evaluation of mammographic density patterns: reproducibility and concordance among scales

    Directory of Open Access Journals (Sweden)

    Garrido-Estepa Macarena

    2010-09-01

    Full Text Available Abstract Background Increased mammographic breast density is a moderate risk factor for breast cancer. Different scales have been proposed for classifying mammographic density. This study sought to assess intra-rater agreement for the most widely used scales (Wolfe, Tabár, BI-RADS and Boyd and compare them in terms of classifying mammograms as high- or low-density. Methods The study covered 3572 mammograms drawn from women included in the DDM-Spain study, carried-out in seven Spanish Autonomous Regions. Each mammogram was read by an expert radiologist and classified using the Wolfe, Tabár, BI-RADS and Boyd scales. In addition, 375 mammograms randomly selected were read a second time to estimate intra-rater agreement for each scale using the kappa statistic. Owing to the ordinal nature of the scales, weighted kappa was computed. The entire set of mammograms (3572 was used to calculate agreement among the different scales in classifying high/low-density patterns, with the kappa statistic being computed on a pair-wise basis. High density was defined as follows: percentage of dense tissue greater than 50% for the Boyd, "heterogeneously dense and extremely dense" categories for the BI-RADS, categories P2 and DY for the Wolfe, and categories IV and V for the Tabár scales. Results There was good agreement between the first and second reading, with weighted kappa values of 0.84 for Wolfe, 0.71 for Tabár, 0.90 for BI-RADS, and 0.92 for Boyd scale. Furthermore, there was substantial agreement among the different scales in classifying high- versus low-density patterns. Agreement was almost perfect between the quantitative scales, Boyd and BI-RADS, and good for those based on the observed pattern, i.e., Tabár and Wolfe (kappa 0.81. Agreement was lower when comparing a pattern-based (Wolfe or Tabár versus a quantitative-based (BI-RADS or Boyd scale. Moreover, the Wolfe and Tabár scales classified more mammograms in the high-risk group, 46.61 and 37

  8. A Monte Carlo Study of the Evolution of the Scale Height of Normal Pulsars in the Galaxy

    Institute of Scientific and Technical Information of China (English)

    Ying-Chun Wei; Xin-Ji Wu; Qiu-He Peng; Na Wang; Jin Zhang

    2005-01-01

    Based on the undisturbed, finite thickness disk gravitational potential,we carried out 3-D Monte Carlo simulations of normal pulsars. We find that their scale height evolves in a similar way for different velocity dispersions (σv): it first increases linearly with time, reaches a peak, then gradually decreases, and finally approaches a stable asymptotic value. The initial velocity dispersion has a very large influence on the scale height. The time evolution of the scale height is studied.When the magnetic decay age is used as the time variable, the observed scale height has a similar trend as the simulated results in the linear stage, from which we derive velocity dispersions in the range 70 ~ 178 km s-1, which are near the statistical result of 90 ~ 270km s-1 for 92 pulsars with known transverse velocities. If the characteristic age is used as the time variable, then the observed and theoretical curves roughly agree for t > 10s yr only if σv < 25km s-1.

  9. Arrays of quasi-hexagonally ordered silica nanopillars with independently controlled areal density, diameter and height gradients

    Science.gov (United States)

    Özdemir, Burcin; Huang, Wenting; Plettl, Alfred; Ziemann, Paul

    2015-03-01

    A consecutive fabrication approach of independently tailored gradients of the topographical parameters distance, diameter and height in arrays of well-ordered nanopillars on smooth SiO2-Si-wafers is presented. For this purpose, previously reported preparation techniques are further developed and combined. First, self-assembly of Au-salt loaded micelles by dip-coating with computer-controlled pulling-out velocities and subsequent hydrogen plasma treatment produce quasi-hexagonally ordered, 2-dimensional arrays of Au nanoparticles (NPs) with unidirectional variations of the interparticle distances along the pulling direction between 50-120 nm. Second, the distance (or areal density) gradient profile received in this way is superimposed with a diameter-controlled gradient profile of the NPs applying a selective photochemical growth technique. For demonstration, a 1D shutter is used for locally defined UV exposure times to prepare Au NP size gradients varying between 12 and 30 nm. Third, these double-gradient NP arrangements serve as etching masks in a following reactive ion etching step delivering arrays of nanopillars. For height gradient generation, the etching time is locally controlled by applying a shutter made from Si wafer piece. Due to the high flexibility of the etching process, the preparation route works on various materials such as cover slips, silicon, silicon oxide, silicon nitride and silicon carbide.

  10. Density scaling relation in Orion A: effects of region selection

    CERN Document Server

    Stanchev, O I; Donkov, S

    2016-01-01

    Recently Stanchev et al. (2015) proposed a technique to derive density scaling relations in a star-forming region from analysis of the probability distribution function of column density. We address the possible dependence of the outcome on the selection of probe zones, applying the method to Planck dust-opacity data on Orion A. The derived steep scaling relation of mean density with index -1.6 in the molecular cloud (so called `Central filament') points to its self-gravitating nature. The result is reproduced also for large parts of the clouds' vicinity which indicates major role of gravity in the energy balance of the entire star-forming region.

  11. Evaluation of mammographic density patterns: reproducibility and concordance among scales

    OpenAIRE

    2010-01-01

    Abstract Background Increased mammographic breast density is a moderate risk factor for breast cancer. Different scales have been proposed for classifying mammographic density. This study sought to assess intra-rater agreement for the most widely used scales (Wolfe, Tabár, BI-RADS and Boyd) and compare them in terms of classifying mammograms as high- or low-density. Methods The study covered 3572 mammograms drawn from women included in the DDM-Spain study, carried-out in seven Spanish Autonom...

  12. Scaling of weight for height in relation to risk of cancer at different sites in a cohort of Canadian women.

    Science.gov (United States)

    Kabat, Geoffrey C; Heo, Moonseong; Miller, Anthony B; Rohan, Thomas E

    2013-01-01

    Many studies have examined the associations of body mass index (weight (kg)/height (m)(2)) with risk of various cancers. However, optimal scaling of weight for height may depend on the population studied. The authors used data from a large cohort study of women (Canadian National Breast Cancer Screening Study, 1980-2000; n = 89,835) to examine how the scaling of weight for height (W/H(x)) influenced the association with risk of 19 different cancers. Cox proportional hazards models were used to estimate the hazard ratio for each cancer site with W/H(x), with x increasing from 0 to 3.0 by increments of 0.1. The correlation between weight and W/H(x) decreased monotonically with increasing x, whereas W/H(x) was minimally correlated with height when x = 1.4. W/H(x) showed significant positive associations with postmenopausal breast cancer, endometrial cancer, kidney cancer, and lung cancer in never smokers. W/H(x) was inversely associated with lung cancer in ever smokers. The value of x for which W/H(x) produced the largest statistically significant hazard ratio ranged from 0.8 (endometrial cancer) to 1.7 (postmenopausal breast cancer). For lung cancer in ever smokers, the inverse association was statistically significant for all values of x. These findings suggest that the scaling of weight for height may vary depending on the cancer site and that optimal scaling may be considerably different from W/H(2) or, alternatively, that a range of scaling should be considered when examining the association of body weight with risk of disease.

  13. Modeling vegetation heights from high resolution stereo aerial photography: an application for broad-scale rangeland monitoring.

    Science.gov (United States)

    Gillan, Jeffrey K; Karl, Jason W; Duniway, Michael; Elaksher, Ahmed

    2014-11-01

    Vertical vegetation structure in rangeland ecosystems can be a valuable indicator for assessing rangeland health and monitoring riparian areas, post-fire recovery, available forage for livestock, and wildlife habitat. Federal land management agencies are directed to monitor and manage rangelands at landscapes scales, but traditional field methods for measuring vegetation heights are often too costly and time consuming to apply at these broad scales. Most emerging remote sensing techniques capable of measuring surface and vegetation height (e.g., LiDAR or synthetic aperture radar) are often too expensive, and require specialized sensors. An alternative remote sensing approach that is potentially more practical for managers is to measure vegetation heights from digital stereo aerial photographs. As aerial photography is already commonly used for rangeland monitoring, acquiring it in stereo enables three-dimensional modeling and estimation of vegetation height. The purpose of this study was to test the feasibility and accuracy of estimating shrub heights from high-resolution (HR, 3-cm ground sampling distance) digital stereo-pair aerial images. Overlapping HR imagery was taken in March 2009 near Lake Mead, Nevada and 5-cm resolution digital surface models (DSMs) were created by photogrammetric methods (aerial triangulation, digital image matching) for twenty-six test plots. We compared the heights of individual shrubs and plot averages derived from the DSMs to field measurements. We found strong positive correlations between field and image measurements for several metrics. Individual shrub heights tended to be underestimated in the imagery, however, accuracy was higher for dense, compact shrubs compared with shrubs with thin branches. Plot averages of shrub height from DSMs were also strongly correlated to field measurements but consistently underestimated. Grasses and forbs were generally too small to be detected with the resolution of the DSMs. Estimates of

  14. Modeling vegetation heights from high resolution stereo aerial photography: an application for broad-scale rangeland monitoring

    Science.gov (United States)

    Gillan, Jeffrey K.; Karl, Jason W.; Duniway, Michael; Elaksher, Ahmed

    2014-01-01

    Vertical vegetation structure in rangeland ecosystems can be a valuable indicator for assessing rangeland health and monitoring riparian areas, post-fire recovery, available forage for livestock, and wildlife habitat. Federal land management agencies are directed to monitor and manage rangelands at landscapes scales, but traditional field methods for measuring vegetation heights are often too costly and time consuming to apply at these broad scales. Most emerging remote sensing techniques capable of measuring surface and vegetation height (e.g., LiDAR or synthetic aperture radar) are often too expensive, and require specialized sensors. An alternative remote sensing approach that is potentially more practical for managers is to measure vegetation heights from digital stereo aerial photographs. As aerial photography is already commonly used for rangeland monitoring, acquiring it in stereo enables three-dimensional modeling and estimation of vegetation height. The purpose of this study was to test the feasibility and accuracy of estimating shrub heights from high-resolution (HR, 3-cm ground sampling distance) digital stereo-pair aerial images. Overlapping HR imagery was taken in March 2009 near Lake Mead, Nevada and 5-cm resolution digital surface models (DSMs) were created by photogrammetric methods (aerial triangulation, digital image matching) for twenty-six test plots. We compared the heights of individual shrubs and plot averages derived from the DSMs to field measurements. We found strong positive correlations between field and image measurements for several metrics. Individual shrub heights tended to be underestimated in the imagery, however, accuracy was higher for dense, compact shrubs compared with shrubs with thin branches. Plot averages of shrub height from DSMs were also strongly correlated to field measurements but consistently underestimated. Grasses and forbs were generally too small to be detected with the resolution of the DSMs. Estimates of

  15. The cosmic web for density perturbations of various scales

    CERN Document Server

    Suhhonenko, I; Liivamägi, L J; Saar, E; Einasto, M; Hütsi, G; Müller, V; Starobinsky, A A; Tago, E; Tempel, E

    2011-01-01

    We follow the evolution of galaxy systems in numerical simulation. Our goal is to understand the role of density perturbations of various scales in the formation and evolution of the cosmic web. We perform numerical simulations with the full power spectrum of perturbations, and with spectrum cut at long wavelengths. Additionally, we have one model, where we cut the intermediate waves. We analyze the density field and study the void sizes and density field clusters in different models. Our analysis shows that the fine structure (groups and clusters of galaxies) is created by small-scale density perturbations of scale $\\leq 8$ \\Mpc. Filaments of galaxies and clusters are created by perturbations of intermediate scale from $\\sim 8$ to $\\sim 32$ \\Mpc, superclusters of galaxies by larger perturbations. We conclude that the scale of the pattern of the cosmic web is determined by density perturbations of scale up to $\\sim 100$ \\Mpc. Larger perturbations do not change the pattern of the web, but modulate the richness...

  16. High-density genetic map construction and QTLs identification for plant height in white jute (Corchorus capsularis L.) using specific locus amplified fragment (SLAF) sequencing.

    Science.gov (United States)

    Tao, Aifen; Huang, Long; Wu, Guifen; Afshar, Reza Keshavarz; Qi, Jianmin; Xu, Jiantang; Fang, Pingping; Lin, Lihui; Zhang, Liwu; Lin, Peiqing

    2017-05-08

    Genetic mapping and quantitative trait locus (QTL) detection are powerful methodologies in plant improvement and breeding. White jute (Corchorus capsularis L.) is an important industrial raw material fiber crop because of its elite characteristics. However, construction of a high-density genetic map and identification of QTLs has been limited in white jute due to a lack of sufficient molecular markers. The specific locus amplified fragment sequencing (SLAF-seq) strategy combines locus-specific amplification and high-throughput sequencing to carry out de novo single nuclear polymorphism (SNP) discovery and large-scale genotyping. In this study, SLAF-seq was employed to obtain sufficient markers to construct a high-density genetic map for white jute. Moreover, with the development of abundant markers, genetic dissection of fiber yield traits such as plant height was also possible. Here, we present QTLs associated with plant height that were identified using our newly constructed genetic linkage groups. An F8 population consisting of 100 lines was developed. In total, 69,446 high-quality SLAFs were detected of which 5,074 SLAFs were polymorphic; 913 polymorphic markers were used for the construction of a genetic map. The average coverage for each SLAF marker was 43-fold in the parents, and 9.8-fold in each F8 individual. A linkage map was constructed that contained 913 SLAFs on 11 linkage groups (LGs) covering 1621.4 cM with an average density of 1.61 cM per locus. Among the 11 LGs, LG1 was the largest with 210 markers, a length of 406.34 cM, and an average distance of 1.93 cM between adjacent markers. LG11 was the smallest with only 25 markers, a length of 29.66 cM, and an average distance of 1.19 cM between adjacent markers. 'SNP_only' markers accounted for 85.54% and were the predominant markers on the map. QTL mapping based on the F8 phenotypes detected 11 plant height QTLs including one major effect QTL across two cultivation locations, with each QTL

  17. Scaling rules for critical current density in anisotropic biaxial superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yingxu, E-mail: yingxuli@swjtu.edu.cn [Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province, School of Mechanics and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Kang, Guozheng [Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province, School of Mechanics and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Gao, Yuanwen, E-mail: ywgao@lzu.edu.cn [Key Laboratory of Mechanics on Environment and Disaster in Western China, The Ministry of Education of China, Lanzhou, Gansu 730000 (China); Department of Mechanics and Engineering Science, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000 (China)

    2016-06-15

    Recent researches highlight the additional anisotropic crystallographic axis within the superconducting plane of high temperature superconductors (HTS), demonstrating the superconducting anisotropy of HTS is better understood in the biaxial frame than the previous uniaxial coordinates within the superconducting layer. To quantitatively evaluate the anisotropy of flux pinning and critical current density in HTS, we extend the scaling rule for single-vortex collective pinning in uniaxial superconductors to account for flux-bundle collective pinning in biaxial superconductors. The scaling results show that in a system of random uncorrected point defects, the field dependence of the critical current density is described by a unified function with the scaled magnetic field of the isotropic superconductor. The obtained angular dependence of the critical current density depicts the main features of experimental observations, considering possible corrections due to the strong-pinning interaction.

  18. Theoretical determination of HI vertical scale heights in the dwarf galaxies: DDO 154, HoII, IC2574 & NGC2366

    CERN Document Server

    Banerjee, Arunima; Brinks, Elias; Bagetakos, Ioannis

    2011-01-01

    In this paper, we model dwarf galaxies as a two-component system of gravitationally coupled stars and atomic hydrogen gas in the external force field of a pseudo-isothermal dark matter halo, and numerically obtain the radial distribution of {H\\,{\\sc i}} vertical scale heights. This is done for a group of four dwarf galaxies (DDO\\,154, Ho\\,II, IC\\,2574 and NGC\\,2366) for which most necessary input parameters are available from observations. The formulation of the equations takes into account the rising rotation curves generally observed in dwarf galaxies. The inclusion of self-gravity of the gas into the model at par with that of the stars results in scale heights that are smaller than what was obtained by previous authors. This is important as the gas scale height is often used for deriving other physical quantities. The inclusion of gas self-gravity is particularly relevant in the case of dwarf galaxies where the gas cannot be considered a minor perturbation to the mass distribution of the stars. We find tha...

  19. Chamberlain Heights Redevelopment: A Large Scale, Cold Climate Study of Affordable Housing Retrofits

    Energy Technology Data Exchange (ETDEWEB)

    Donnelly, K. [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States); Mahle, M. [Consortium for Advanced Residential Buildings (CARB), Norwalk, CT (United States)

    2012-03-01

    The City of Meriden Housing Authority (MHA) collaborated with affordable housing developer Jonathon Rose Companies (JRC) to complete a gut renovation of 124 residential units in the Chamberlain Heights retrofit project. The affordable housing community is made up of 36 buildings in duplex and quad configurations located on 22 acres within two miles of downtown Meriden, CT. The final post-retrofit analysis showed 40-45% source energy savings over the existing pre-retrofit conditions.

  20. Multi-scale wavelet analysis of TOPEX/Poseidon altimeter significant wave height in eastern China seas

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The multi-scale characteristics of wave significant height (Hs) in eastern China seas were revealed by multi-scale wavelet analysis. In order to understand the relation between wave and wind, the TOPEX/Poseidon measurements of Hs and wind speed were analyzed. The result showed that Hs and wind speed change in multi-scale at one-, two-month, half-, one- and two-year cycles. But in a larger time scale, the variations in Hs and wind speed are different. Hs has a five-year cycle similar to the cycle of ENSO variation, while the wind speed has no such cycle. In the time domain, the correlation between Hs and ENSO is unclear.

  1. Large Scale Magnetic Fields: Density Power Spectrum in Redshift Space

    Indian Academy of Sciences (India)

    Rajesh Gopal; Shiv K. Sethi

    2003-09-01

    We compute the density redshift-space power spectrum in the presence of tangled magnetic fields and compare it with existing observations. Our analysis shows that if these magnetic fields originated in the early universe then it is possible to construct models for which the shape of the power spectrum agrees with the large scale slope of the observed power spectrum. However requiring compatibility with observed CMBR anisotropies, the normalization of the power spectrum is too low for magnetic fields to have significant impact on the large scale structure at present. Magnetic fields of a more recent origin generically give density power spectrum ∝ 4 which doesn’t agree with the shape of the observed power spectrum at any scale. Magnetic fields generate curl modes of the velocity field which increase both the quadrupole and hexadecapole of the redshift space power spectrum. For curl modes, the hexadecapole dominates over quadrupole. So the presence of curl modes could be indicated by an anomalously large hexadecapole, which has not yet been computed from observation. It appears difficult to construct models in which tangled magnetic fields could have played a major role in shaping the large scale structure in the present epoch. However if they did, one of the best ways to infer their presence would be from the redshift space effects in the density power spectrum.

  2. Approximation of the breast height diameter distribution of two-cohort stands by mixture models III Kernel density estimators vs mixture models

    Science.gov (United States)

    Rafal Podlaski; Francis A. Roesch

    2014-01-01

    Two-component mixtures of either the Weibull distribution or the gamma distribution and the kernel density estimator were used for describing the diameter at breast height (dbh) empirical distributions of two-cohort stands. The data consisted of study plots from the Å wietokrzyski National Park (central Poland) and areas close to and including the North Carolina section...

  3. Linear Scaling Density Functional Calculations with Gaussian Orbitals

    Science.gov (United States)

    Scuseria, Gustavo E.

    1999-01-01

    Recent advances in linear scaling algorithms that circumvent the computational bottlenecks of large-scale electronic structure simulations make it possible to carry out density functional calculations with Gaussian orbitals on molecules containing more than 1000 atoms and 15000 basis functions using current workstations and personal computers. This paper discusses the recent theoretical developments that have led to these advances and demonstrates in a series of benchmark calculations the present capabilities of state-of-the-art computational quantum chemistry programs for the prediction of molecular structure and properties.

  4. Maximum length scale in density based topology optimization

    DEFF Research Database (Denmark)

    Lazarov, Boyan Stefanov; Wang, Fengwen

    2017-01-01

    The focus of this work is on two new techniques for imposing maximum length scale in topology optimization. Restrictions on the maximum length scale provide designers with full control over the optimized structure and open possibilities to tailor the optimized design for broader range...... of manufacturing processes by fulfilling the associated technological constraints. One of the proposed methods is based on combination of several filters and builds on top of the classical density filtering which can be viewed as a low pass filter applied to the design parametrization. The main idea...

  5. Estimation of probability densities using scale-free field theories.

    Science.gov (United States)

    Kinney, Justin B

    2014-07-01

    The question of how best to estimate a continuous probability density from finite data is an intriguing open problem at the interface of statistics and physics. Previous work has argued that this problem can be addressed in a natural way using methods from statistical field theory. Here I describe results that allow this field-theoretic approach to be rapidly and deterministically computed in low dimensions, making it practical for use in day-to-day data analysis. Importantly, this approach does not impose a privileged length scale for smoothness of the inferred probability density, but rather learns a natural length scale from the data due to the tradeoff between goodness of fit and an Occam factor. Open source software implementing this method in one and two dimensions is provided.

  6. Density Functional Theory and Materials Modeling at Atomistic Length Scales

    Directory of Open Access Journals (Sweden)

    Swapan K. Ghosh

    2002-04-01

    Full Text Available Abstract: We discuss the basic concepts of density functional theory (DFT as applied to materials modeling in the microscopic, mesoscopic and macroscopic length scales. The picture that emerges is that of a single unified framework for the study of both quantum and classical systems. While for quantum DFT, the central equation is a one-particle Schrodinger-like Kohn-Sham equation, the classical DFT consists of Boltzmann type distributions, both corresponding to a system of noninteracting particles in the field of a density-dependent effective potential, the exact functional form of which is unknown. One therefore approximates the exchange-correlation potential for quantum systems and the excess free energy density functional or the direct correlation functions for classical systems. Illustrative applications of quantum DFT to microscopic modeling of molecular interaction and that of classical DFT to a mesoscopic modeling of soft condensed matter systems are highlighted.

  7. The Relationship Between Flying Height Variation of the Flying Optical Head and Statistical Recording Density in Near—field Optical Recording

    Institute of Scientific and Technical Information of China (English)

    PEIXiandeng,; ZHANGXiaoga; HUANGHao

    2003-01-01

    This paper models the head-disk cou-pling in waveguide probe near-field recording, and derives the relationship curve between full width at half maxi-mum (FWHM) of static light distribution as well as static recording density and near-field coupling distance by com-puter simulation. Then after defining the FWHM of sta-tistical light distribution and statistical recording density,we discuss the relationship between flying height variation of the flying optical head and statistical recording density in near-field optical recording.

  8. Effects of thermal inflation on small scale density perturbations

    CERN Document Server

    Hong, Sungwook E; Lee, Young Jae; Stewart, Ewan D; Zoe, Heeseung

    2015-01-01

    In cosmological scenarios with thermal inflation, extra eras of moduli matter domination, thermal inflation and flaton matter domination exist between primordial inflation and the radiation domination of Big Bang nucleosynthesis. During these eras, cosmological perturbations on small scales can enter and re-exit the horizon, modifying the power spectrum on those scales. The largest modified scale, $k_\\mathrm{b}$, touches the horizon size when the expansion changes from deflation to inflation at the transition from moduli domination to thermal inflation. We analytically calculate the evolution of perturbations from moduli domination through thermal inflation and evaluate the curvature perturbation on the constant radiation density hypersurface at the end of thermal inflation to determine the late time curvature perturbation. Our resulting transfer function suppresses the power spectrum by a factor $\\sim 50$ at $k \\gg k_\\mathrm{b}$, with $k_\\mathrm{b}$ corresponding to anywhere from megaparsec to subparsec scal...

  9. Quantitative, nondestructive assessment of beech scale (Hemiptera: Cryptococcidae) density using digital image analysis of wax masses.

    Science.gov (United States)

    Teale, Stephen A; Letkowski, Steven; Matusick, George; Stehman, Stephen V; Castello, John D

    2009-08-01

    Beech scale, Cryptococcus fagisuga Lindinger, is a non-native invasive insect associated with beech bark disease. A quantitative method of measuring viable scale density at the levels of the individual tree and localized bark patches was developed. Bark patches (10 cm(2)) were removed at 0, 1, and 2 m above the ground and at the four cardinal directions from 13 trees in northern New York and 12 trees in northern Michigan. Digital photographs of each patch were made, and the wax mass area was measured from two random 1-cm(2) subsamples on each bark patch using image analysis software. Viable scale insects were counted after removing the wax under a dissecting microscope. Separate regression analyses at the whole tree level for the New York and Michigan sites each showed a strong positive relationship of wax mass area with the number of underlying viable scale insects. The relationships for the New York and Michigan data were not significantly different from each other, and when pooling data from the two sites, there was still a significant positive relationship between wax mass area and the number of scale insects. The relationships between viable scale insects and wax mass area were different at the 0-, 1-, and 2-m sampling heights but do not seem to affect the relationship. This method does not disrupt the insect or its interactions with the host tree.

  10. Scaling from individual plants to the globe in an Earth System Model: height structured competition and carbon cycling

    Science.gov (United States)

    Weng, E.; Malyshev, S.; Lichstein, J. W.; Farrior, C. E.; Dybzinski, R.; Zhang, T.; Shevliakova, E.; Pacala, S. W.

    2014-12-01

    The long-term and large scale dynamics of ecosystems are in large part determined by the performances of individual plants in competition with one another for light, water and nutrients. Woody biomass, a pool of carbon (C) larger than that in the atmosphere, exists because of height-structured competition for light. However, none of the current Earth System Models that predict climate change and C cycle feedbacks includes a mechanistic formulation for height-structured competition for light, or an explicit scaling from individual plants to the globe. In this study, we incorporate height-structured competition and explicit scaling from individuals to ecosystems into the land model (LM3) currently used in the Earth System Models developed by the Geophysical Fluid Dynamics Laboratory based on the Perfect Plasticity Approximation model (PPA), which has been shown to scale accurately from individual plants to stands in individual-based simulation models of plant competition for light, water and nutrients. Because of the tractability of the PPA, the coupled LM3-PPA model is able to include a large number of phenomena across a range of spatial and temporal scales, and still retain computational and mathematical tractability. We test a range of predictions against data from the temperate forests in northern USA. The results show the model predictions agree with diurnal and annual C fluxes, growth rates of individual trees in the canopy and understory, tree size distributions, and species-level population dynamics during succession. We also show how the competitively optimal allocation strategy shifts at different atmospheric CO2 concentrations due to competition with alternative strategies in the model. The results show that the competitively optimal allocation of carbon to leaves, wood, and fine roots depends on the atmospheric CO2 concentration, and that C sinks caused by CO2 fertilization in forests limited by light and water are down-regulated if allocation tracks

  11. Invistigation on Canopy Height and Density Differentiations in the Managed and Unmanaged Forest Stands Using LIDAR Data (case Study: Shastkalateh Forest, Gorgan)

    Science.gov (United States)

    Shataee, Sh.; Mohammadi, J.

    2015-12-01

    Forest management plans are interesting to keep the forest stand natural composite and structure after silvicultural and management treatments. In order to investigate on stand differences made by management treatments, comparing of these stands with unmanaged stands as natural forests is necessary. Aerial laser scanners are providing suitable 3D information to map the horizontal and vertical characteristics of forest structures. In this study, different of canopy height and canopy cover variances between managed and unmanaged forest stands as well as in two dominant forest types were investigated using Lidar data in Dr. Bahramnia forest, Northern Iran. The in-situ information was gathered from 308 circular plots by a random systematic sampling designs. The low lidar cloud point data were used to generate accurate DEM and DSM models and plot-based height statistics metrics and canopy cover characteristics. The significant analyses were done by independent T-test between two stands in same dominant forest types. Results showed that there are no significant differences between canopy cover mean in two stands as well as forest types. Result of statistically analysis on height characteristics showed that there are a decreasing the forest height and its variance in the managed forest compared to unmanaged stands. In addition, there is a significant difference between maximum, range, and mean heights of two stands in 99 percent confidence level. However, there is no significant difference between standard deviation and canopy height variance of managed and unmanged stands. These results showd that accomplished management treatments and cuttings could lead to reducing of height variances and converting multi-layers stands to two or single layers. Results are also showed that the canopy cover densities in the managed forest stands are changing from high dense cover to dense cover.

  12. Applications of large-scale density functional theory in biology

    Science.gov (United States)

    Cole, Daniel J.; Hine, Nicholas D. M.

    2016-10-01

    Density functional theory (DFT) has become a routine tool for the computation of electronic structure in the physics, materials and chemistry fields. Yet the application of traditional DFT to problems in the biological sciences is hindered, to a large extent, by the unfavourable scaling of the computational effort with system size. Here, we review some of the major software and functionality advances that enable insightful electronic structure calculations to be performed on systems comprising many thousands of atoms. We describe some of the early applications of large-scale DFT to the computation of the electronic properties and structure of biomolecules, as well as to paradigmatic problems in enzymology, metalloproteins, photosynthesis and computer-aided drug design. With this review, we hope to demonstrate that first principles modelling of biological structure-function relationships are approaching a reality.

  13. A New Questionnaire for Estimating the Severity of Visual Height Intolerance and Acrophobia by a Metric Interval Scale.

    Science.gov (United States)

    Huppert, Doreen; Grill, Eva; Brandt, Thomas

    2017-01-01

    To construct and validate a short scale for the assessment of the severity of visual height intolerance (vHI) and acrophobia. The questionnaire was developed from two earlier representative epidemiological studies (n = 5,529). Items were applied in a telephone survey of a representative population-based sample. A total of 1,960 persons were included. The life-time prevalence of vHI was 32.7% (f: 36.1%; m: 28.4%); 12% of these persons fulfilled the psychiatric criteria of acrophobia. Rasch analysis of 11 items on severity, symptoms, and triggers resulted in an 8-item scale with good fit to the model. The score differentiated well between persons with and without acrophobia. The distribution of the scores on the metric scale of the questionnaires of those individuals with acrophobia is separate and distinct from that of susceptibles without acrophobia, although there is some overlap. Our proposed short questionnaire (vHISS, see Table 1 and Supplementary Material) allows a continuous quantification of the severity of vHI within a metric interval scale from 0 to 13. The diagnosis of acrophobia can be established by including two additional questions.

  14. Nonlinear density fluctuation field theory for large scale structure

    Institute of Scientific and Technical Information of China (English)

    Yang Zhang; Hai-Xing Miao

    2009-01-01

    We develop an effective field theory of density fluctuations for a Newtonian self-gravitating N-body system in quasi-equilibrium and apply it to a homogeneous uni-verse with small density fluctuations. Keeping the density fluctuations up to second or-der, we obtain the nonlinear field equation of 2-pt correlation ξ(r), which contains 3-pt correlation and formal ultra-violet divergences. By the Groth-Peebles hierarchical ansatz and mass renormalization, the equation becomes closed with two new terms beyond the Gaussian approximation, and their coefficients are taken as parameters. The analytic solu-tion is obtained in terms of the hypergeometric functions, which is checked numerically.With one single set of two fixed parameters, the correlation ξ(r) and the corresponding power spectrum P(k) simultaneously match the results from all the major surveys, such as APM, SDSS, 2dfGRS, and REFLEX. The model gives a unifying understanding of several seemingly unrelated features of large scale structure from a field-theoretical per-spective. The theory is worth extending to study the evolution effects in an expanding universe.

  15. Using Newton's law and geophysical bounds on mass density contrast to ensure consistency between gravity and height data

    DEFF Research Database (Denmark)

    Strykowski, Gabriel; Larsen, Jacob Norby

    2000-01-01

    In this paper we advocate the use of Newton's law of gravitational attraction to ensure perfect consistency between gravity and height data. Starting with the absolute gravity on the topography we decompose this signal into a number of quantities associated with physics of the system. To model...... gravitational attraction from topography we use DTM and Newton's law of gravitational attraction. A residual part of the gravity signal is interpreted as inconsistency between gravity and heights. In the paper we discuss a method by which such inconsistency (at least in principle) can be decomposed...... into a "gravity error" and a "terrain error". In practice such separation is not possible because the two types of error are nearly 100% correlated. The inconsistency can be interpreted as a measure of ambiguity of the gravity-terrain models which are consistent with a set of measured/interpolated data. We...

  16. Utilization of O4 Slant Column Density to Derive Aerosol Layer Height from a Spaceborne UV-Visible Hyperspectral Sensor: Sensitivity and Case Study

    Science.gov (United States)

    Park, Sang Seo; Kim, Jhoon; Lee, Hanlim; Torres, Omar; Lee, Kwang-Mog; Lee, Sang Deok

    2016-01-01

    The sensitivities of oxygen-dimer (O4) slant column densities (SCDs) to changes in aerosol layer height are investigated using the simulated radiances by a radiative transfer model, the linearized pseudo-spherical vector discrete ordinate radiative transfer (VLIDORT), and the Differential Optical Absorption Spectroscopy (DOAS) technique. The sensitivities of the O4 index (O4I), which is defined as dividing O4 SCD by 10(exp 40) sq molecules cm(exp -5), to aerosol types and optical properties are also evaluated and compared. Among the O4 absorption bands at 340, 360, 380, and 477 nm, the O4 absorption band at 477 nm is found to be the most suitable to retrieve the aerosol effective height. However, the O4I at 477 nm is significantly influenced not only by the aerosol layer effective height but also by aerosol vertical profiles, optical properties including single scattering albedo (SSA), aerosol optical depth (AOD), particle size, and surface albedo. Overall, the error of the retrieved aerosol effective height is estimated to be 1276, 846, and 739 m for dust, non-absorbing, and absorbing aerosol, respectively, assuming knowledge on the aerosol vertical distribution shape. Using radiance data from the Ozone Monitoring Instrument (OMI), a new algorithm is developed to derive the aerosol effective height over East Asia after the determination of the aerosol type and AOD from the MODerate resolution Imaging Spectroradiometer (MODIS). About 80% of retrieved aerosol effective heights are within the error range of 1 km compared to those obtained from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) measurements on thick aerosol layer cases.

  17. Utilization of O4 Slant Column Density to Derive Aerosol Layer Height from a Space-Borne UV-Visible Hyperspectral Sensor: Sensitivity and Case Study

    Science.gov (United States)

    Park, Sang Seo; Kim, Jhoon; Lee, Hanlim; Torres, Omar; Lee, Kwang-Mog; Lee, Sang Deok

    2016-01-01

    The sensitivities of oxygen-dimer (O4) slant column densities (SCDs) to changes in aerosol layer height are investigated using the simulated radiances by a radiative transfer model, the linearized pseudo-spherical vector discrete ordinate radiative transfer (VLIDORT), and the differential optical absorption spectroscopy (DOAS) technique. The sensitivities of the O4 index (O4I), which is defined as dividing O4 SCD by 10(sup 40) molecules (sup 2) per centimeters(sup -5), to aerosol types and optical properties are also evaluated and compared. Among the O4 absorption bands at 340, 360, 380, and 477 nanometers, the O4 absorption band at 477 nanometers is found to be the most suitable to retrieve the aerosol effective height. However, the O4I at 477 nanometers is significantly influenced not only by the aerosol layer effective height but also by aerosol vertical profiles, optical properties including single scattering albedo (SSA), aerosol optical depth (AOD), particle size, and surface albedo. Overall, the error of the retrieved aerosol effective height is estimated to be 1276, 846, and 739 meters for dust, non-absorbing, and absorbing aerosol, respectively, assuming knowledge on the aerosol vertical distribution shape. Using radiance data from the Ozone Monitoring Instrument (OMI), a new algorithm is developed to derive the aerosol effective height over East Asia after the determination of the aerosol type and AOD from the MODerate resolution Imaging Spectroradiometer (MODIS). About 80 percent of retrieved aerosol effective heights are within the error range of 1 kilometer compared to those obtained from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) measurements on thick aerosol layer cases.

  18. Utilization of O4 Slant Column Density to Derive Aerosol Layer Height from a Space-Borne UV-Visible Hyperspectral Sensor: Sensitivity and Case Study

    Science.gov (United States)

    Park, Sang Seo; Kim, Jhoon; Lee, Hanlim; Torres, Omar; Lee, Kwang-Mog; Lee, Sang Deok

    2016-01-01

    The sensitivities of oxygen-dimer (O4) slant column densities (SCDs) to changes in aerosol layer height are investigated using the simulated radiances by a radiative transfer model, the linearized pseudo-spherical vector discrete ordinate radiative transfer (VLIDORT), and the differential optical absorption spectroscopy (DOAS) technique. The sensitivities of the O4 index (O4I), which is defined as dividing O4 SCD by 10(sup 40) molecules (sup 2) per centimeters(sup -5), to aerosol types and optical properties are also evaluated and compared. Among the O4 absorption bands at 340, 360, 380, and 477 nanometers, the O4 absorption band at 477 nanometers is found to be the most suitable to retrieve the aerosol effective height. However, the O4I at 477 nanometers is significantly influenced not only by the aerosol layer effective height but also by aerosol vertical profiles, optical properties including single scattering albedo (SSA), aerosol optical depth (AOD), particle size, and surface albedo. Overall, the error of the retrieved aerosol effective height is estimated to be 1276, 846, and 739 meters for dust, non-absorbing, and absorbing aerosol, respectively, assuming knowledge on the aerosol vertical distribution shape. Using radiance data from the Ozone Monitoring Instrument (OMI), a new algorithm is developed to derive the aerosol effective height over East Asia after the determination of the aerosol type and AOD from the MODerate resolution Imaging Spectroradiometer (MODIS). About 80 percent of retrieved aerosol effective heights are within the error range of 1 kilometer compared to those obtained from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) measurements on thick aerosol layer cases.

  19. Surface-Height Determination of Crevassed Glaciers-Mathematical Principles of an Autoadaptive Density-Dimension Algorithm and Validation Using ICESat-2 Simulator (SIMPL) Data

    Science.gov (United States)

    Herzfeld, Ute C.; Trantow, Thomas M.; Harding, David; Dabney, Philip W.

    2017-01-01

    Glacial acceleration is a main source of uncertainty in sea-level-change assessment. Measurement of ice-surface heights with a spatial and temporal resolution that not only allows elevation-change calculation, but also captures ice-surface morphology and its changes is required to aid in investigations of the geophysical processes associated with glacial acceleration.The Advanced Topographic Laser Altimeter System aboard NASAs future ICESat-2 Mission (launch 2017) will implement multibeam micropulse photon-counting lidar altimetry aimed at measuring ice-surface heights at 0.7-m along-track spacing. The instrument is designed to resolve spatial and temporal variability of rapidly changing glaciers and ice sheets and the Arctic sea ice. The new technology requires the development of a new mathematical algorithm for the retrieval of height information.We introduce the density-dimension algorithm (DDA) that utilizes the radial basis function to calculate a weighted density as a form of data aggregation in the photon cloud and considers density an additional dimension as an aid in auto-adaptive threshold determination. The auto-adaptive capability of the algorithm is necessary to separate returns from noise and signal photons under changing environmental conditions. The algorithm is evaluated using data collected with an ICESat-2 simulator instrument, the Slope Imaging Multi-polarization Photon-counting Lidar, over the heavily crevassed Giesecke Braer in Northwestern Greenland in summer 2015. Results demonstrate that ICESat-2 may be expected to provide ice-surface height measurements over crevassed glaciers and other complex ice surfaces. The DDA is generally applicable for the analysis of airborne and spaceborne micropulse photon-counting lidar data over complex and simple surfaces.

  20. Monitoring and Modeling of Large-Scale Pattern of Forest Height and Biomass based on the Metabolic Scaling Theory and Water-Energy Balance Equation

    Science.gov (United States)

    CHOI, S.; Myneni, R. B.; Knyazikhin, Y.; Park, T.

    2015-12-01

    This study applies the metabolic scaling theory (MST) and water-energy balance equation (PM: Penman-Monteith) to monitor and model the large-scale pattern of forest height and biomass. The WBE and PM theories grant a generalized mechanistic understanding of relationships between the forest structure and multiple geospatial predictors including topography and climatic variables. We successfully expanded the average trend and predictions of the MST and PM by including eco-regional and plant functional type variations. Our model now accounts for plant interaction, self-competition and disturbance effects to alleviate known limitations of the MST. The topographic heterogeneity and climate seasonality are additionally incorporated in the model predictions. A simple and clear mechanistic understanding in the model is promising for prognostic applications in contrast to conventional black-box approaches. This study provides baseline maps (circa 2005; 1-km2 grids) of the maximum forest canopy heights and aboveground biomass over the continental USA. Their future projections are also delivered using various climate scenarios. The NASA Earth Exchange (NEX) Downscaled Climate Projections (NEX-DCP30) dataset is used in this task.

  1. Landscape Soil Respiration Fluxes are Related to Leaf Area Index, Stand Height and Density, and Soil Nitrogen in Rocky Mountain Subalpine Forests

    Science.gov (United States)

    Berryman, E.; Bradford, J. B.; Hawbaker, T. J.; Birdsey, R.; Ryan, M. G.

    2015-12-01

    There is a recent multi-agency push for accurate assessments of terrestrial carbon stocks and fluxes in the United States. Assessing the state of the carbon cycle in the US requires estimates of stocks and fluxes at large spatial scales. Such assessments are difficult, especially for soil respiration, which dominates ecosystem respiration and is notoriously highly variable over space and time. Here, we report three consecutive years of measurement of soil respiration fluxes in three 1 km2 subalpine forest landscapes: Fraser Experimental Forest (Colorado), Glacier Lakes Ecosystems Experimental Site ("GLEES", Wyoming), and Niwot Ridge (Colorado). Plots were established following the protocol of the US Forest Service's Forest Inventory and Analysis (FIA) Program. Clusters of plots were distributed across the landscape in a 0.25 km grid pattern. From 2004 through 2006, measurements of soil respiration were made once monthly during the growing season and twice during snowpack coverage for each year. Annual cumulative soil respiration was 6.10 (+/- 0.21) Mg ha-1y-1 for Fraser, 6.55 (+/- 0.27) Mg ha-1y-1 for GLEES, and 6.97 (+/- 0.20) Mg ha-1y-1 for Niwot. Variability in annual cumulative soil respiration varied by less than 20% among the three subalpine forests, despite differences in terrain, climate, disturbance history and anthropogenic nitrogen deposition. We quantified the relationship between respiration fluxes and commonly-measured forest properties and found that soil respiration was nonlinearly related to leaf area index, peaking around 2.5 m2m-2 then slowly declining. Annual litterfall (FA) was subtracted from soil respiration (FR) to calculate total belowground carbon flux (TBCF), which declined with increasing tree height, density and soil nitrogen. This landscape analysis of soil respiration confirmed experimentally-derived principles governing carbon fluxes in forests: as trees age and get taller, and in high-fertility areas, carbon flux to roots declines

  2. EXAMINATION OF THE SURFACE FREE ENERGY AND ACID-BASE PROPERTIES OF CELLULOSE BY THE COLUMN WICKING TECHNIQUE AND THE CRITICAL PACKING HEIGHT/DENSITY

    Institute of Scientific and Technical Information of China (English)

    Qing Shen; Jian-feng Hu; Qing-feng Gu

    2004-01-01

    The column wicking technique was applied to estimate the surface free energy of cellulose, the importance of which is to obtain a real effective capillary radius, Reff, initially from the plot of Washburn penetration distance versus time.Since the cellulose sample could not be packed with good reproducibility, therefore, Reff can not be obtained readily from the slope of the plot. A method was developed in this paper by uniting all apparent packing heights with a unique value to deduce a real effective capillary radius. Based on the defined critical packing height related to the critical packing density, the surface free energy and acid-base properties of cellulose Sigma C8002 were estimated.

  3. Basic wood density of Acacia melanoxylon R.Br related to sample tree height, tree and site; Densidad basica de la madera de Acacia melanoxylon R. Br en relacion con la altura de muestreo, el arbol y el sitio

    Energy Technology Data Exchange (ETDEWEB)

    Igartua Dora, D. V.; Monteoliva, S.

    2009-07-01

    The aim of the work was to assess basic wood density variations of Acacia melanoxylon R.Br according to sample tree height, tree, and site. Twenty trees were selected from four sites in Buenos Aires Province, Argentine. Wood density was determined over two disc samples at four tree height (base, breast height, 30% and 50% of total tree height). According to determined ages, some trees were divided into two groups according to age (26-32 years and 9-12 years) and data were analyzed with an analysis of variance according to mixed model where tree was the random effect. Trees represent 74 % of total random variance. Within tree, axial tendency of wood density was to decrease from the base toward breast height and then its value was stable to the top. This was consistent across all sites and age groups. Forest resource growing at Los Tuelches site presented the highest basic wood density. (Author) 40 refs.

  4. Gram-scale fractionation of nanodiamonds by density gradient ultracentrifugation

    KAUST Repository

    Peng, Wei

    2013-01-01

    Size is a defining characteristic of nanoparticles; it influences their optical and electronic properties as well as their interactions with molecules and macromolecules. Producing nanoparticles with narrow size distributions remains one of the main challenges to their utilization. At this time, the number of practical approaches to optimize the size distribution of nanoparticles in many interesting materials systems, including diamond nanocrystals, remains limited. Diamond nanocrystals synthesized by detonation protocols-so-called detonation nanodiamonds (DNDs)-are promising systems for drug delivery, photonics, and composites. DNDs are composed of primary particles with diameters mainly <10 nm and their aggregates (ca. 10-500 nm). Here, we introduce a large-scale approach to rate-zonal density gradient ultracentrifugation to obtain monodispersed fractions of nanoparticles in high yields. We use this method to fractionate a highly concentrated and stable aqueous solution of DNDs and to investigate the size distribution of various fractions by dynamic light scattering, analytical ultracentrifugation, transmission electron microscopy and powder X-ray diffraction. This fractionation method enabled us to separate gram-scale amounts of DNDs into several size ranges within a relatively short period of time. In addition, the high product yields obtained for each fraction allowed us to apply the fractionation method iteratively to a particular size range of particles and to collect various fractions of highly monodispersed primary particles. Our method paves the way for in-depth studies of the physical and optical properties, growth, and aggregation mechanism of DNDs. Applications requiring DNDs with specific particle or aggregate sizes are now within reach. © 2013 The Royal Society of Chemistry.

  5. Scale heights and equivalent widths of the iron K-shell lines in the Galactic diffuse X-ray emission

    CERN Document Server

    Yamauchi, Shigeo; Nobukawa, Masayoshi; Uchiyama, Hideki; Koyama, Katsuji

    2016-01-01

    This paper reports the analysis of the X-ray spectra of the Galactic diffuse X-ray emission (GDXE) in the Suzaku archive. The fluxes of the Fe I K alpha (6.4 keV), Fe XXV,He alpha (6.7 keV) and Fe XXVI Ly alpha (6.97 keV) lines are separately determined. From the latitude distributions, we confirm that the GDXE is decomposed into the Galactic center (GCXE), the Galactic bulge (GBXE) and the Galactic ridge (GRXE) X-ray emissions. The scale heights (SHs) of the Fe XXV He alpha line of the GCXE, GBXE and GRXE are determined to be ~40, ~310 and ~140 pc, while those of the Fe I K alpha line are ~30, ~160 and ~70 pc, respectively. The mean equivalent widths (EWs) of the sum of the Fe XXV He alpha and Fe XXVI Ly alpha lines are ~750 eV, ~600 eV and ~550 eV, while those of the Fe I K alpha line are ~150~eV, ~60~eV and ~100~eV for the GCXE, GBXE and GRXE, respectively. The origin of the GBXE, GRXE and GCXE is separately discussed based on the new results of the SHs and EWs, in comparison with those of the Cataclysmic ...

  6. Daubechies wavelets for linear scaling density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Mohr, Stephan [Institut für Physik, Universität Basel, Klingelbergstr. 82, 4056 Basel (Switzerland); Univ. Grenoble Alpes, INAC-SP2M, F-38000 Grenoble, France and CEA, INAC-SP2M, F-38000 Grenoble (France); Ratcliff, Laura E.; Genovese, Luigi; Caliste, Damien; Deutsch, Thierry [Univ. Grenoble Alpes, INAC-SP2M, F-38000 Grenoble, France and CEA, INAC-SP2M, F-38000 Grenoble (France); Boulanger, Paul [Univ. Grenoble Alpes, INAC-SP2M, F-38000 Grenoble, France and CEA, INAC-SP2M, F-38000 Grenoble (France); Institut Néel, CNRS and Université Joseph Fourier, B.P. 166, 38042 Grenoble Cedex 09 (France); Goedecker, Stefan [Institut für Physik, Universität Basel, Klingelbergstr. 82, 4056 Basel (Switzerland)

    2014-05-28

    We demonstrate that Daubechies wavelets can be used to construct a minimal set of optimized localized adaptively contracted basis functions in which the Kohn-Sham orbitals can be represented with an arbitrarily high, controllable precision. Ground state energies and the forces acting on the ions can be calculated in this basis with the same accuracy as if they were calculated directly in a Daubechies wavelets basis, provided that the amplitude of these adaptively contracted basis functions is sufficiently small on the surface of the localization region, which is guaranteed by the optimization procedure described in this work. This approach reduces the computational costs of density functional theory calculations, and can be combined with sparse matrix algebra to obtain linear scaling with respect to the number of electrons in the system. Calculations on systems of 10 000 atoms or more thus become feasible in a systematic basis set with moderate computational resources. Further computational savings can be achieved by exploiting the similarity of the adaptively contracted basis functions for closely related environments, e.g., in geometry optimizations or combined calculations of neutral and charged systems.

  7. Can shoulder muscle coordination during the support scale at ring height be replicated during training exercises in gymnastics?

    Science.gov (United States)

    Bernasconi, Sylvain M; Tordi, Nicolas R; Parratte, Bernard M; Rouillon, Jean-Denis R

    2009-11-01

    The support scale at ring height, the swallow, is a difficult strength element, usually performed in gymnastics. Coaches try to simulate the swallow position during training to strengthen muscles, specifically in the position used for competition. However, the real effect of this position's simulation on muscle force and coordination and consequently on the muscle activity has not been determined. The purpose of the study was to compare muscle activity and coordination during a swallow performed on the rings, using a counterweight and during 2 training exercises using dumbbells or barbells, respectively. Six top-level gymnasts participated in the study. Electromyograms from the biceps brachii, triceps brachii, deltoideus (clavicular part), pectoralis major, serratus anterior, infraspinatus, trapezius (middle part), and latissimus dorsi in the right shoulder were collected during the 4 exercises and analyzed using root mean square (RMS) and mean power frequency (MPF). The RMS were normalized to the maximal voluntary contraction, and a co-activation index was also determined between biceps and triceps brachii. Our results show specific shoulder muscle coordination for each exercise. As compared with the swallow on the rings, the pectoralis major participates less in shoulder flexion during the counterweight exercise, whereas the deltoideus is more activated during the dumbbells exercise (p < 0.05). The barbell exercise reduces the participation of the serratus anterior in stabilizing the scapula (p < 0.05). Training exercises must therefore be chosen with knowledge of the specific muscle coordination induced by each. The counterweight exercise preserves the pectoralis major. The barbell exercise reduces participation of the serratus anterior. The dumbbells exercise may be useful to prepare the rotator cuff muscles carefully for use.

  8. Local average height distribution of fluctuating interfaces

    Science.gov (United States)

    Smith, Naftali R.; Meerson, Baruch; Sasorov, Pavel V.

    2017-01-01

    Height fluctuations of growing surfaces can be characterized by the probability distribution of height in a spatial point at a finite time. Recently there has been spectacular progress in the studies of this quantity for the Kardar-Parisi-Zhang (KPZ) equation in 1 +1 dimensions. Here we notice that, at or above a critical dimension, the finite-time one-point height distribution is ill defined in a broad class of linear surface growth models unless the model is regularized at small scales. The regularization via a system-dependent small-scale cutoff leads to a partial loss of universality. As a possible alternative, we introduce a local average height. For the linear models, the probability density of this quantity is well defined in any dimension. The weak-noise theory for these models yields the "optimal path" of the interface conditioned on a nonequilibrium fluctuation of the local average height. As an illustration, we consider the conserved Edwards-Wilkinson (EW) equation, where, without regularization, the finite-time one-point height distribution is ill defined in all physical dimensions. We also determine the optimal path of the interface in a closely related problem of the finite-time height-difference distribution for the nonconserved EW equation in 1 +1 dimension. Finally, we discuss a UV catastrophe in the finite-time one-point distribution of height in the (nonregularized) KPZ equation in 2 +1 dimensions.

  9. A relationship between the weighted density approximation and the local-scaling transformation version of density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Diez, Reinaldo Pis [CEQUINOR, Centro de Quimica Inorganica (CONICET, UNLP), Departamento de Quimica, Facultad de Ciencias Exactas, UNLP CC 962, B1900AVV La Plata (Argentina); Karasiev, Valentin V [Centro de Qimica, Instituto Venezolano de Investigaciones Cientificas, IVIC, Apartado 21827, Caracas 1020-A (Venezuela)

    2003-07-14

    A relationship between the auxiliary density, {rho}(r), defined within the framework of the weighted density approximation and the kinetic energy modulating factor, A{sub N}([{rho}(r)]; r), which appears in the local-scaling transformation version of density functional theory is presented. This relationship imposes the condition of positiveness on the kinetic energy modulating factor and this, in turn, leads to an important mathematical condition on any approximate kinetic energy density functional. It is shown that two well-known approximate kinetic energy density functionals do not satisfy the above relationship at distances very close to the nucleus. By forcing a given approximate kinetic energy density functional to obey the above condition, both the kinetic and exchange energies can be obtained within a framework similar to that of the weighted density approximation. Results on some closed-shell atomic systems provide support for those ideas.

  10. Localized density matrix minimization and linear scaling algorithms

    CERN Document Server

    Lai, Rongjie

    2015-01-01

    We propose a convex variational approach to compute localized density matrices for both zero temperature and finite temperature cases, by adding an entry-wise $\\ell_1$ regularization to the free energy of the quantum system. Based on the fact that the density matrix decays exponential away from the diagonal for insulating system or system at finite temperature, the proposed $\\ell_1$ regularized variational method provides a nice way to approximate the original quantum system. We provide theoretical analysis of the approximation behavior and also design convergence guaranteed numerical algorithms based on Bregman iteration. More importantly, the $\\ell_1$ regularized system naturally leads to localized density matrices with banded structure, which enables us to develop approximating algorithms to find the localized density matrices with computation cost linearly dependent on the problem size.

  11. An Automatic Mosaicking Algorithm for the Generation of a Large-Scale Forest Height Map Using Spaceborne Repeat-Pass InSAR Correlation Magnitude

    Directory of Open Access Journals (Sweden)

    Yang Lei

    2015-05-01

    Full Text Available This paper describes an automatic mosaicking algorithm for creating large-scale mosaic maps of forest height. In contrast to existing mosaicking approaches through using SAR backscatter power and/or InSAR phase, this paper utilizes the forest height estimates that are inverted from spaceborne repeat-pass cross-pol InSAR correlation magnitude. By using repeat-pass InSAR correlation measurements that are dominated by temporal decorrelation, it has been shown that a simplified inversion approach can be utilized to create a height-sensitive measure over the whole interferometric scene, where two scene-wide fitting parameters are able to characterize the mean behavior of the random motion and dielectric changes of the volume scatterers within the scene. In order to combine these single-scene results into a mosaic, a matrix formulation is used with nonlinear least squares and observations in adjacent-scene overlap areas to create a self-consistent estimate of forest height over the larger region. This automated mosaicking method has the benefit of suppressing the global fitting error and, thus, mitigating the “wallpapering” problem in the manual mosaicking process. The algorithm is validated over the U.S. state of Maine by using InSAR correlation magnitude data from ALOS/PALSAR and comparing the inverted forest height with Laser Vegetation Imaging Sensor (LVIS height and National Biomass and Carbon Dataset (NBCD basal area weighted (BAW height. This paper serves as a companion work to previously demonstrated results, the combination of which is meant to be an observational prototype for NASA’s DESDynI-R (now called NISAR and JAXA’s ALOS-2 satellite missions.

  12. The origin of linear scaling Fock matrix calculation with density prescreening

    Energy Technology Data Exchange (ETDEWEB)

    Mitin, Alexander V., E-mail: mitin@phys.chem.msu.ru [Chemistry Department, Moscow State University, Moscow, 119991 (Russian Federation)

    2015-12-31

    A theorem was proven, which reads that the number of nonzero two-electron integrals scales linearly with respect to the number of basis functions for large molecular systems. This permits to show that linear scaling property of the Fock matrix calculation with using density prescreening arises due to linear scaling properties of the number of nonzero two-electron integrals and the number of leading matrix elements of density matrix. This property is reinforced by employing the density prescreening technique. The use of the density difference prescreening further improves the linear scaling property of the Fock matrix calculation method. As a result, the linear scaling regime of the Fock matrix calculation can begin from the number of basis functions of 2000–3000 in dependence on the basis function type in molecular calculations. It was also shown that the conventional algorithm of Fock matrix calculation from stored nonzero two-electron integrals with density prescreening possesses linear scaling property.

  13. Scaling of the Density Peak with Pellet Injection in ITER*%Scaling of the Density Peak with Pellet Injection in ITER*

    Institute of Scientific and Technical Information of China (English)

    P. KLAYWITTAPHAT; T. ONJUN

    2012-01-01

    Scalings of the density peak and pellet penetration length in ITER are developed based on simulations using 1.5D BALDUR integrated predictive modeling code. In these simulations , the pellet ablation is described by the Neutral Gas Shielding (NGS) model with grad-B drift effect taken into account. The NGS pellet model is coupled with a plasma core transport model, which is a combination of an MMM95 anomalous transport model and an NCLASS neoclassical transport model. The BALDUR code with a combination of MMM95 and NCLASS models, together with the NGS model, is used to simulate the time evolution of plasma current, ion and electron temperatures, and density profiles for ITER standard type I ELMy H-mode discharges during the pellet injection. As a result, the scaling of the density peak and pellet penetration length at peak density can be established using this set of predictive simulations that covers a wide range of ITER plasma conditions and pellet parameters. The multiple regression technique is utilized in the development of the scalings. It is found that the scaling for density at center is sensitive to both the plasma and pellet parameters; whereas the scalings for density and location of the additional peak are sensitive to the pellet parameters only.

  14. Density scaling and quasiuniversality of flow-event statistics for athermal plastic flows

    DEFF Research Database (Denmark)

    Lerner, Edan; Bailey, Nicholas; Dyre, J. C.

    2014-01-01

    the flow events. We show that simulations at a single density in conjunction with an equilibrium-liquid simulation at the same density allow one to predict the plastic flow-event statistics at other densities. This is done by applying the recently established “hidden scale invariance” of simple liquids...

  15. Density-dependent prey mortality is determined by the spatial scale of predator foraging.

    Science.gov (United States)

    McCarthy, Erin K; White, J Wilson

    2016-02-01

    Foraging theory predicts which prey patches predators should target. However, in most habitats, what constitutes a 'patch' and how prey density is calculated are subjective concepts and depend on the spatial scale at which the predator (or scientist) is observing. Moreover, the predator's 'foraging scale' affects prey population dynamics: predators should produce directly density-dependent (DDD) prey mortality at the foraging scale, but inversely density-dependent (IDD) mortality (safety-in-numbers) at smaller scales. We performed the first experimental test of these predictions using behavioral assays with guppies (Poecilia reticulata) feeding on bloodworm 'prey' patches. The guppy's foraging scale had already been estimated in a prior study. Our experimental results confirmed theoretical predictions: predation was IDD when prey were aggregated at a scale smaller than the foraging scale, but not when prey were aggregated at larger scales. These results could be used to predict outcomes of predator-prey interactions in continuous, non-discrete habitats in the field.

  16. Length scale and manufacturability in density-based topology optimization

    DEFF Research Database (Denmark)

    Lazarov, Boyan Stefanov; Wang, Fengwen; Sigmund, Ole

    2016-01-01

    Since its original introduction in structural design, density-based topology optimization has been applied to a number of other fields such as microelectromechanical systems, photonics, acoustics and fluid mechanics. The methodology has been well accepted in industrial design processes where it c......, well-defined designs with robust performances. The overview discusses the limitations, the advantages and the associated computational costs. The review is completed with optimized designs for minimum compliance, mechanism design and heat transfer.......Since its original introduction in structural design, density-based topology optimization has been applied to a number of other fields such as microelectromechanical systems, photonics, acoustics and fluid mechanics. The methodology has been well accepted in industrial design processes where it can...

  17. Large Scale Density Estimation of Blue and Fin Whales (LSD)

    Science.gov (United States)

    2014-09-30

    interactions with human activity requires knowledge of how many animals are present in an area during a specific time period. Many marine mammal species ...Ocean at Wake Island will then be applied to the same species in the Indian Ocean at the CTBTO location at Diego Garcia. 1. Develop and implement...proposed density estimation method is also highly dependent on call rate inputs, which are used in the development of species specific multipliers for

  18. Effect of recombinant human growth hormone on changes in height, bone mineral density, and body composition over 1-2 years in children with Hurler or Hunter syndrome.

    Science.gov (United States)

    Polgreen, Lynda E; Thomas, William; Orchard, Paul J; Whitley, Chester B; Miller, Bradley S

    2014-02-01

    Patients with Hurler or Hunter syndrome typically have moderate to severe growth deficiencies despite therapy with allogeneic hematopoietic stem cell transplantation and/or enzyme replacement therapy. It is unknown whether treatment with recombinant human growth hormone (hGH) can improve growth in these children. The objectives of this study were to determine the effects of hGH on growth, bone mineral density (BMD), and body composition in children with Hurler or Hunter syndrome enrolled in a longitudinal observational study. The difference in annual change in outcomes between hGH treated and untreated subjects was estimated by longitudinal regression models that adjusted for age, Tanner stage, and sex where appropriate. We report on 23 participants who completed at least 2 annual study visits (10 [43%] treated with hGH): Hurler syndrome (n=13) average age of 9.8 ± 3.1 years (range 5.3-13.6 years; 54% female) and Hunter syndrome (n=10) average age of 12.0 ± 2.7 years (range 7.0-17.0 years; 0% female). As a group, children with Hurler or Hunter syndrome treated with hGH had no difference in annual change in height (growth velocity) compared to those untreated with hGH. Growth velocity in hGH treated individuals ranged from -0.4 to 8.1cm/year and from 0.3 to 6.6 cm/year in the untreated individuals. Among children with Hunter syndrome, 100% (N=4) of those treated but only 50% of those untreated with hGH had an annual increase in height standard deviation score (SDS). Of the individuals treated with hGH, those with GHD had a trend towards higher annualized growth velocity compared to those without GHD (6.5 ± 1.9 cm/year vs. 3.5 ± 2.1cm/year; p=.050). Children treated with hGH had greater annual gains in BMD and lean body mass. In conclusion, although as a group we found no significant difference in growth between individuals treated versus not treated with hGH, individual response was highly variable and we are unable to predict who will respond to treatment. Thus

  19. Scaling laws for density correlations and fluctuations in multiparticle dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, E.A. de [Universitaire Instelling Antwerpen, Wilrijk (Belgium). Dept. of Physics]|[Interuniversity Inst. for High Energies, Brussels (Belgium); Dremin, I.M. [Rossijskaya Akademiya Nauk, Moscow (Russian Federation). Fizicheskij Inst.; Kittel, W. [Nationaal Inst. voor Kernfysica en Hoge-Energiefysica (NIKHEF), Nijmegen (Netherlands)

    1996-05-01

    Experimental data on particle correlations and fluctuations in various high-energy multiparticle collisions are presented, with special emphasis on evidence for scaling-law evolution in small phase-space domains. The notions of intermittency and fractality as related to the above findings are described. Phenomenological and theoretical work on the subject is reviewed. (orig.).

  20. Milky Way red dwarfs in the BoRG survey; galactic scale-height and the distribution of dwarf stars in WFC3 imaging

    Energy Technology Data Exchange (ETDEWEB)

    Holwerda, B. W.; Bouwens, R. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Trenti, M. [Kavli Institute for Cosmology and Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom); Clarkson, W. [Department of Natural Sciences College of Arts, Sciences and Letters, University of Michigan-Dearborn 4901 Evergreen Road, Dearborn, MI 48128 (United States); Sahu, K.; Bradley, L.; Stiavelli, M.; Pirzkal, N.; Ryan, R. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); De Marchi, G. [European Space Agency, ESA-ESTEC, Keplerlaan 1, 2200 AG Noordwijk (Netherlands); Andersen, M., E-mail: holwerda@strw.leidenuniv.nl [UJF-Grenoble 1/CNRS-INSU, Institut de Planétologie et d' Astrophysique de Grenoble (IPAG) UMR 5274, F-38041 Grenoble (France)

    2014-06-10

    We present a tally of Milky Way late-type dwarf stars in 68 Wide Field Camera 3 (WFC3) pure-parallel fields (227 arcmin{sup 2}) from the Brightest of Reionizing Galaxies survey for high-redshift galaxies. Using spectroscopically identified M-dwarfs in two public surveys, the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey and the Early Release Science mosaics, we identify a morphological selection criterion using the half-light radius (r {sub 50}), a near-infrared J – H, G – J color region where M-dwarfs are found, and a V – J relation with M-dwarf subtype. We apply this morphological selection of stellar objects, color-color selection of M-dwarfs, and optical-near-infrared color subtyping to compile a catalog of 274 M-dwarfs belonging to the disk of the Milky Way with a limiting magnitude of m {sub F125W} < 24(AB). Based on the M-dwarf statistics, we conclude that (1) the previously identified north-south discrepancy in M-dwarf numbers persists in our sample; there are more M-dwarfs in the northern fields on average than in southern ones, (2) the Milky Way's single disk scale-height for M-dwarfs is 0.3-4 kpc, depending on subtype, (3) the scale-height depends on M-dwarf subtype with early types (M0-4) high scale-height (z {sub 0} = 3-4 kpc) and later types M5 and above in the thin disk (z {sub 0} = 0.3-0.5 kpc), (4) a second component is visible in the vertical distribution, with a different, much higher scale-height in the southern fields compared to the northern ones. We report the M-dwarf component of the Sagittarius stream in one of our fields with 11 confirmed M-dwarfs, seven of which are at the stream's distance. In addition to the M-dwarf catalog, we report the discovery of 1 T-dwarfs and 30 L-dwarfs from their near-infrared colors. The dwarf scale-height and the relative low incidence in our fields of L- and T-dwarfs in these fields makes it unlikely that these stars will be interlopers in great numbers in color-selected samples of

  1. Holography and the scale-invariance of density fluctuations

    CERN Document Server

    Magueijo, J; Contaldi, C R; Magueijo, Joao; Smolin, Lee; Contaldi, Carlo R.

    2006-01-01

    We study a scenario for the very early universe in which there is a fast phase transition from a non-geometric, high temperature phase to a low temperature, geometric phase described by a classical solution to the Einstein equations. In spite of the absence of a classical metric, the thermodynamics of the high temperature phase may be described by making use of the holographic principle. The thermal spectrum of fluctuations in the high temperature phase manifest themselves after the phase transition as a scale invariant spectrum of fluctuations. A simple model of the phase transition confirms that the near scale invariance of the fluctuations is natural; but the model also withstands detailed comparison with the data.

  2. Holography and the scale invariance of density fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Magueijo, Joao [Perimeter Institute for Theoretical Physics, 31 Caroline St N, Waterloo N2 L 2Y5 (Canada); Smolin, Lee [Perimeter Institute for Theoretical Physics, 31 Caroline St N, Waterloo N2 L 2Y5 (Canada); Contaldi, Carlo R [Theoretical Physics Group, Imperial College, Prince Consort Road, London SW7 2BZ (United Kingdom)

    2007-07-21

    We study a scenario for the very early universe in which there is a fast phase transition from a non-geometric, high temperature phase to a low temperature, geometric phase described by a classical solution to the Einstein equations. In spite of the absence of a classical metric, the thermodynamics of the high temperature phase may be described by making use of the holographic principle. The thermal spectrum of fluctuations in the high temperature phase manifests itself after the phase transition as a scale-invariant spectrum of fluctuations. A simple model of the phase transition confirms that the near scale invariance of the fluctuations is natural, but the model also withstands a detailed comparison with the data.

  3. Density scaling as a property of strongly correlating viscous liquids

    OpenAIRE

    Schrøder, Thomas; Pedersen, Ulf Rørbæk; Bailey, Nicholas; Toxværd, Søren; Dyre, J.C.

    2008-01-01

    Results from molecular dynamics simulations of two viscous molecular model liquids -- the Lewis-Wahnstrom model of ortho-terphenyl and an asymmetric dumbbell model -- are reported. We demonstrate that the liquids have a ``hidden'' approximate scale invariance: Equilibrium potential energy fluctuations are accurately described by inverse power law (IPL) potentials, the radial distribution functions are accurately reproduced by the IPL's, and the radial distribution functions obey the IPL predi...

  4. Theta height and Faltings height

    CERN Document Server

    Pazuki, F

    2009-01-01

    Using original ideas from J.-B. Bost and S. David, we provide an explicit comparison between the Theta height and the stable Faltings height of a principally polarized abelian variety. We also give as an application an explicit upper bound on the number of K-rational points of a curve of genus g>1 over a number filed K under a conjecture of S. Lang and J. Silverman. We complete the study with a comparison between differential lattice structures.

  5. Revisiting the density scaling of the non-interacting kinetic energy.

    Science.gov (United States)

    Borgoo, Alex; Teale, Andrew M; Tozer, David J

    2014-07-28

    Scaling relations play an important role in the understanding and development of approximate functionals in density functional theory. Recently, a number of these relationships have been redefined in terms of the Kohn-Sham orbitals [Calderín, Phys. Rev. A: At., Mol., Opt. Phys., 2013, 86, 032510]. For density scaling the author proposed a procedure involving a multiplicative scaling of the Kohn-Sham orbitals whilst keeping their occupation numbers fixed. In the present work, the differences between this scaling with fixed occupation numbers and that of previous studies, where the particle number change implied by the scaling was accommodated through the use of the grand canonical ensemble, are examined. We introduce the terms orbital and ensemble density scaling for these approaches, respectively. The natural ambiguity of the density scaling of the non-interacting kinetic energy functional is examined and the ancillary definitions implicit in each approach are highlighted and compared. As a consequence of these differences, Calderín recovered a homogeneity of degree 1 for the non-interacting kinetic energy functional under orbital scaling, contrasting recent work by the present authors [J. Chem. Phys., 2012, 136, 034101] where the functional was found to be inhomogeneous under ensemble density scaling. Furthermore, we show that the orbital scaling result follows directly from the linearity and the single-particle nature of the kinetic energy operator. The inhomogeneity of the non-interacting kinetic energy functional under ensemble density scaling can be quantified by defining an effective homogeneity. This quantity is shown to recover the homogeneity values for important approximate forms that are exact for limiting cases such as the uniform electron gas and one-electron systems. We argue that the ensemble density scaling provides more insight into the development of new functional forms.

  6. Updated sesame genome assembly and fine mapping of plant height and seed coat color QTLs using a new high-density genetic map.

    Science.gov (United States)

    Wang, Linhai; Xia, Qiuju; Zhang, Yanxin; Zhu, Xiaodong; Zhu, Xiaofeng; Li, Donghua; Ni, Xuemei; Gao, Yuan; Xiang, Haitao; Wei, Xin; Yu, Jingyin; Quan, Zhiwu; Zhang, Xiurong

    2016-01-05

    Sesame is an important high-quality oil seed crop. The sesame genome was de novo sequenced and assembled in 2014 (version 1.0); however, the number of anchored pseudomolecules was higher than the chromosome number (2n = 2x = 26) due to the lack of a high-density genetic map with 13 linkage groups. We resequenced a permanent population consisting of 430 recombinant inbred lines and constructed a genetic map to improve the sesame genome assembly. We successfully anchored 327 scaffolds onto 13 pseudomolecules. The new genome assembly (version 2.0) included 97.5 % of the scaffolds greater than 150 kb in size present in assembly version 1.0 and increased the total pseudomolecule length from 233.7 to 258.4 Mb with 94.3 % of the genome assembled and 97.2 % of the predicted gene models anchored. Based on the new genome assembly, a bin map including 1,522 bins spanning 1090.99 cM was generated and used to identified 41 quantitative trait loci (QTLs) for sesame plant height and 9 for seed coat color. The plant height-related QTLs explained 3-24 % the phenotypic variation (mean value, 8 %), and 29 of them were detected in at least two field trials. Two major loci (qPH-8.2 and qPH-3.3) that contributed 23 and 18 % of the plant height were located in 350 and 928-kb spaces on Chr8 and Chr3, respectively. qPH-3.3, is predicted to be responsible for the semi-dwarf sesame plant phenotype and contains 102 candidate genes. This is the first report of a sesame semi-dwarf locus and provides an interesting opportunity for a plant architecture study of the sesame. For the sesame seed coat color, the QTLs of the color spaces L*, a*, and b* were detected with contribution rates of 3-46 %. qSCb-4.1 contributed approximately 39 % of the b* value and was located on Chr4 in a 199.9-kb space. A list of 32 candidate genes for the locus, including a predicted black seed coat-related gene, was determined by screening the newly anchored genome. This study offers a high-density

  7. Experimental Investigation on Effect of Fin Height on Microscale Heat Transfer and Fluid Flow for Macro Scale Industrial Applications

    Science.gov (United States)

    Cheng, K. X.; Goh, A. L.; Hadi, M.; Ooi, K. T.

    2017-03-01

    Microchannel for macro geometry application is gaining popularity particularly in aerospace, biomedical and photovoltaic. A novel method of employing microchannel in macro geometry at lower cost using conventional machining methods has been developed. A solid cylinder on outer diameter 19.4 mm is placed concentrically into a copper pipe of inner diameter 20 mm, forming an annular microchannel with 300 μm gap. This study takes a step further by introducing surface profile of different heights on the surface of solid cylinder and investigating the effect on two main design objectives- increasing heat removal capability at same pumping power and reducing pumping power for the same heat removal duty. Four surface profiles -parallel fins as well as fins with height of 0.1, 0.2 and 0.3 mm, were investigated experimentally at constant heat flux at Reynolds number from 690 to 4600. The amount of fluid in the microchannel, channel length of 30 mm, bifurcating angle of 75 degrees and mean hydraulic diameter of 600 μm are kept as constant parameters. A plain insert is used as benchmark for comparison of enhancement. In this study, insert with fins of 0.3 mm attains the highest enhancement of 43 percent increment in heat transfer as compared to plain insert using the same pumping power. While keeping the heat removal duty constant, the same insert is able to perform the duty using less than 50 percent the pumping power required by the plain insert at low Reynolds numbers.

  8. Effective spatial scales for evaluating environmental determinants of population density in Yakushima macaques.

    Science.gov (United States)

    Agetsuma, Naoki; Koda, Ryosuke; Tsujino, Riyou; Agetsuma-Yanagihara, Yoshimi

    2015-02-01

    Population densities of wildlife species tend to be correlated with resource productivity of habitats. However, wildlife density has been greatly modified by increasing human influences. For effective conservation, we must first identify the significant factors that affect wildlife density, and then determine the extent of the areas in which the factors should be managed. Here, we propose a protocol that accomplishes these two tasks. The main threats to wildlife are thought to be habitat alteration and hunting, with increases in alien carnivores being a concern that has arisen recently. Here, we examined the effect of these anthropogenic disturbances, as well as natural factors, on the local density of Yakushima macaques (Macaca fuscata yakui). We surveyed macaque densities at 30 sites across their habitat using data from 403 automatic cameras. We quantified the effect of natural vegetation (broad-leaved forest, mixed coniferous/broad-leaved forest, etc.), altered vegetation (forestry area and agricultural land), hunting pressure, and density of feral domestic dogs (Canis familiaris). The effect of each vegetation type was analyzed at numerous spatial scales (between 150 and 3,600-m radii from the camera locations) to determine the best scale for explaining macaque density (effective spatial scale). A model-selection procedure (generalized linear mixed model) was used to detect significant factors affecting macaque density. We detected that the most effective spatial scale was 400 m in radius, a scale that corresponded to group range size of the macaques. At this scale, the amount of broad-leaved forest was selected as a positive factor, whereas mixed forest and forestry area were selected as negative factors for macaque density. This study demonstrated the importance of the simultaneous evaluation of all possible factors of wildlife population density at the appropriate spatial scale.

  9. Gram-scale fractionation of nanodiamonds by density gradient ultracentrifugation

    Science.gov (United States)

    Peng, Wei; Mahfouz, Remi; Pan, Jun; Hou, Yuanfang; Beaujuge, Pierre M.; Bakr, Osman M.

    2013-05-01

    determination of mpDND density. See DOI: 10.1039/c3nr00990d

  10. Navicula height

    DEFF Research Database (Denmark)

    Rathleff, M; Nielsen, RG; Olesen, Christian Gammelgaard;

    2008-01-01

    position and relaxed standing posture. Excessive movement of the navicula is considered a predisposing factor in the development of shin splits. No single direct static measurement of navicula height has yet shown to predict a high degree of mid foot movement. The purpose of this study was to investigate...

  11. Wuthering Heights

    NARCIS (Netherlands)

    Bronte, Emily

    2005-01-01

    Wuthering Heights tells the story of a romance between two youngsters: Catherine Earnshaw and an orphan boy, Heathcliff. After she rejects him for a boy from a better background he develops a lust for revenge that takes over his life. In attempting to win her back and destroy those he blames for his

  12. Scaling from individuals to ecosystems in an Earth System Model using a mathematically tractable model of height-structured competition for light

    Directory of Open Access Journals (Sweden)

    E. S. Weng

    2014-12-01

    Full Text Available The long-term and large scale dynamics of ecosystems are in large part determined by the performances of individual plants in competition with one another for light, water and nutrients. Woody biomass, a pool of carbon (C larger than 50% of atmospheric CO2, exists because of height-structured competition for light. However, most of the current Earth System Models that predict climate change and C cycle feedbacks lack both a mechanistic formulation for height-structured competition for light and an explicit scaling from individual plants to the globe. In this study, we incorporate height-structured competition and explicit scaling from individuals to ecosystems into the land model (LM3 currently used in the Earth System Models developed by the Geophysical Fluid Dynamics Laboratory (GFDL. The height-structured formulation is based on the Perfect Plasticity Approximation (PPA, which has been shown to accurately scale from individual-level plant competition for light, water and nutrients to the dynamics of whole communities. Because of the tractability of the PPA, the coupled LM3–PPA model is able to include a large number of phenomena across a range of spatial and temporal scales, and still retain computational tractability, as well as close linkages to mathematically tractable forms of the model. We test a range of predictions against data from temperate broadleaved forests in the northern USA. The results show the model predictions agree with diurnal and annual C fluxes, growth rates of individual trees in the canopy and understory, tree size distributions, and species-level population dynamics during succession. We also show how the competitively optimal allocation strategy – the strategy that can competitively exclude all others – shifts as a function of the atmospheric CO2 concentration. This strategy is referred as an evolutionary stable strategy (ESS in the ecological literature and is typically not the same as a productivity- or

  13. Scaling from individuals to ecosystems in an Earth System Model using a mathematically tractable model of height-structured competition for light

    Science.gov (United States)

    Weng, E. S.; Malyshev, S.; Lichstein, J. W.; Farrior, C. E.; Dybzinski, R.; Zhang, T.; Shevliakova, E.; Pacala, S. W.

    2014-12-01

    The long-term and large scale dynamics of ecosystems are in large part determined by the performances of individual plants in competition with one another for light, water and nutrients. Woody biomass, a pool of carbon (C) larger than 50% of atmospheric CO2, exists because of height-structured competition for light. However, most of the current Earth System Models that predict climate change and C cycle feedbacks lack both a mechanistic formulation for height-structured competition for light and an explicit scaling from individual plants to the globe. In this study, we incorporate height-structured competition and explicit scaling from individuals to ecosystems into the land model (LM3) currently used in the Earth System Models developed by the Geophysical Fluid Dynamics Laboratory (GFDL). The height-structured formulation is based on the Perfect Plasticity Approximation (PPA), which has been shown to accurately scale from individual-level plant competition for light, water and nutrients to the dynamics of whole communities. Because of the tractability of the PPA, the coupled LM3-PPA model is able to include a large number of phenomena across a range of spatial and temporal scales, and still retain computational tractability, as well as close linkages to mathematically tractable forms of the model. We test a range of predictions against data from temperate broadleaved forests in the northern USA. The results show the model predictions agree with diurnal and annual C fluxes, growth rates of individual trees in the canopy and understory, tree size distributions, and species-level population dynamics during succession. We also show how the competitively optimal allocation strategy - the strategy that can competitively exclude all others - shifts as a function of the atmospheric CO2 concentration. This strategy is referred as an evolutionary stable strategy (ESS) in the ecological literature and is typically not the same as a productivity- or growth-maximizing strategy

  14. Multiscale spatial density smoothing: an application to large-scale radiological survey and anomaly detection

    CERN Document Server

    Tansey, Wesley; Reinhart, Alex; Scott, James G

    2015-01-01

    We consider the problem of estimating a spatially varying density function, motivated by problems that arise in large-scale radiological survey and anomaly detection. In this context, the density functions to be estimated are the background gamma-ray energy spectra at sites spread across a large geographical area, such as nuclear production and waste-storage sites, military bases, medical facilities, university campuses, or the downtown of a city. Several challenges combine to make this a difficult problem. First, the spectral density at any given spatial location may have both smooth and non-smooth features. Second, the spatial correlation in these density functions is neither stationary nor locally isotropic. Third, the spatial correlation decays at different length scales at different locations in the support of the underlying density. Finally, at some spatial locations, there is very little data. We present a method called multiscale spatial density smoothing that successfully addresses these challenges. ...

  15. Stabilization of electron-scale turbulence by electron density gradient in national spherical torus experiment

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz Ruiz, J.; White, A. E. [MIT-Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Ren, Y.; Guttenfelder, W.; Kaye, S. M.; Leblanc, B. P.; Mazzucato, E. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Lee, K. C. [National Fusion Research Institute, Daejeon (Korea, Republic of); Domier, C. W. [University of California at Davis, Davis, California 95616 (United States); Smith, D. R. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Yuh, H. [Nova Photonics, Inc., Princeton, New Jersey 08540 (United States)

    2015-12-15

    Theory and experiments have shown that electron temperature gradient (ETG) turbulence on the electron gyro-scale, k{sub ⊥}ρ{sub e} ≲ 1, can be responsible for anomalous electron thermal transport in NSTX. Electron scale (high-k) turbulence is diagnosed in NSTX with a high-k microwave scattering system [D. R. Smith et al., Rev. Sci. Instrum. 79, 123501 (2008)]. Here we report on stabilization effects of the electron density gradient on electron-scale density fluctuations in a set of neutral beam injection heated H-mode plasmas. We found that the absence of high-k density fluctuations from measurements is correlated with large equilibrium density gradient, which is shown to be consistent with linear stabilization of ETG modes due to the density gradient using the analytical ETG linear threshold in F. Jenko et al. [Phys. Plasmas 8, 4096 (2001)] and linear gyrokinetic simulations with GS2 [M. Kotschenreuther et al., Comput. Phys. Commun. 88, 128 (1995)]. We also found that the observed power of electron-scale turbulence (when it exists) is anti-correlated with the equilibrium density gradient, suggesting density gradient as a nonlinear stabilizing mechanism. Higher density gradients give rise to lower values of the plasma frame frequency, calculated based on the Doppler shift of the measured density fluctuations. Linear gyrokinetic simulations show that higher values of the electron density gradient reduce the value of the real frequency, in agreement with experimental observation. Nonlinear electron-scale gyrokinetic simulations show that high electron density gradient reduces electron heat flux and stiffness, and increases the ETG nonlinear threshold, consistent with experimental observations.

  16. L-Band SAR Backscatter Related to Forest Cover, Height and Aboveground Biomass at Multiple Spatial Scales across Denmark

    DEFF Research Database (Denmark)

    Joshi, Neha P.; Mitchard, Edward T A; Schumacher, Johannes;

    2015-01-01

    a strong linear relation (R2 = 0.79 at 250-m scale). In areas of high fractional forest cover, there is a slight decline in backscatter as AGB increases, indicating signal attenuation. The two results demonstrate that accounting for spatial scale and variations in forest structure, such as cover...... fraction, will greatly benefit establishing adequate plot-sizes for SAR calibration and the accuracy of derived AGB maps....

  17. Navicula height

    DEFF Research Database (Denmark)

    Mølgaard, Carsten Møller; Olesen Gammelgaard, Christian; Nielsen, R. G.;

    2008-01-01

    In 1996 Cornwall and McPoil discovered that the static measurement of the rearfoot angle while standing on one leg in a relaxed position, could serve as a clinical indicator of the maximum amount of rearfoot eversion during walking. Due to the close relationship between midfoot and rearfoot motio...... the relationship between static measurements, using Navicual Drop Test and One Leg Standing (OLS) and the dynamic measurements of minimal navicula height loaded (NHL) and navicula drop (ΔNH)...

  18. Waist-to-Height Ratio and Triglycerides/High-Density Lipoprotein Cholesterol Were the Optimal Predictors of Metabolic Syndrome in Uighur Men and Women in Xinjiang, China.

    Science.gov (United States)

    Chen, Bang-Dang; Yang, Yi-Ning; Ma, Yi-Tong; Pan, Shuo; He, Chun-Hui; Liu, Fen; Ma, Xiang; Fu, Zhen-Yan; Li, Xiao-Mei; Xie, Xiang; Zheng, Ying-Ying

    2015-06-01

    This study aimed to identify the best single predictor of metabolic syndrome by comparing the predictive ability of various anthropometric and atherogenic parameters among a Uighur population in Xinjiang, northwest China. A total of 4767 Uighur participants were selected from the Cardiovascular Risk Survey (CRS), which was carried out from October, 2007, to March, 2010. Anthropometric data, blood pressure, serum concentration of serum total cholesterol (TC), triglycerides (TGs), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and fasting glucose were documented. Prevalence of metabolic syndrome and its individual components were confirmed according to International Diabetes Federation (IDF) criteria. Area under the receiver operating characteristic curve (AUC) of each variable for the presence of metabolic syndrome was compared. The sensitivity (Sen), specificity (Spe), distance in the receiver operating characteristic (ROC) curve, and cutoffs of each variable for the presence of metabolic syndrome were calculated. In all, 23.7% of men had the metabolic syndrome, whereas 40.1% of women had the metabolic syndrome in a Uighur population in Xinjiang; the prevalence of metabolic syndrome in women was significantly higher than that in men (P<0.001). In men, the waist-to-height ratio (WHtR) had the highest AUC value (AUC=0.838); it was followed by TGs/HDL-C (AUC=0.826), body mass index (BMI) (AUC=0.812), waist-to-hip ratio (WHR) (AUC=0.781), and body adiposity index (BAI) (AUC=0.709). In women, the TGs/HDL-C had the highest AUC value (AUC=0.815); it was followed by WHtR (AUC=0.780), WHR (AUC=0.730), BMI (AUC=0.719), and BAI (AUC=0.699). Similarly, among all five anthropometric and atherogenic parameters, the WHtR had the shortest ROC distance of 0.32 (Sen=85.40%, Spe=71.6%), and the optimal cutoff for WHtR was 0.55 in men. In women, TGs/HDL-C had the shortest ROC distance of 0.35 (Sen=75.29%, Spe=75.18%), and the optimal cutoff

  19. How many predictors in species distribution models at the landscape scale? Land use versus LiDAR-derived canopy height

    NARCIS (Netherlands)

    Ficetola, G.F.; Bonardi, A.; Mücher, C.A.; Gilissen, N.L.M.; Padoa-Schioppa, E.

    2014-01-01

    At the local spatial scale, land-use variables are often employed as predictors for ecological niche models (ENMs). Remote sensing can provide additional synoptic information describing vegetation structure in detail. However, there is limited knowledge on which environmental variables and how many

  20. Relationships between human population density and burned area at continental and global scales.

    Science.gov (United States)

    Bistinas, Ioannis; Oom, Duarte; Sá, Ana C L; Harrison, Sandy P; Prentice, I Colin; Pereira, José M C

    2013-01-01

    We explore the large spatial variation in the relationship between population density and burned area, using continental-scale Geographically Weighted Regression (GWR) based on 13 years of satellite-derived burned area maps from the global fire emissions database (GFED) and the human population density from the gridded population of the world (GPW 2005). Significant relationships are observed over 51.5% of the global land area, and the area affected varies from continent to continent: population density has a significant impact on fire over most of Asia and Africa but is important in explaining fire over area in croplands. Overall, the relationship between population density and burned area is non-monotonic: burned area initially increases with population density and then decreases when population density exceeds a threshold. These thresholds vary regionally. Our study contributes to improved understanding of how human activities relate to burned area, and should contribute to a better estimate of atmospheric emissions from biomass burning.

  1. The scaling of contact rates with population density for the infectious disease models.

    Science.gov (United States)

    Hu, Hao; Nigmatulina, Karima; Eckhoff, Philip

    2013-08-01

    Contact rates and patterns among individuals in a geographic area drive transmission of directly-transmitted pathogens, making it essential to understand and estimate contacts for simulation of disease dynamics. Under the uniform mixing assumption, one of two mechanisms is typically used to describe the relation between contact rate and population density: density-dependent or frequency-dependent. Based on existing evidence of population threshold and human mobility patterns, we formulated a spatial contact model to describe the appropriate form of transmission with initial growth at low density and saturation at higher density. We show that the two mechanisms are extreme cases that do not capture real population movement across all scales. Empirical data of human and wildlife diseases indicate that a nonlinear function may work better when looking at the full spectrum of densities. This estimation can be applied to large areas with population mixing in general activities. For crowds with unusually large densities (e.g., transportation terminals, stadiums, or mass gatherings), the lack of organized social contact structure deviates the physical contacts towards a special case of the spatial contact model - the dynamics of kinetic gas molecule collision. In this case, an ideal gas model with van der Waals correction fits well; existing movement observation data and the contact rate between individuals is estimated using kinetic theory. A complete picture of contact rate scaling with population density may help clarify the definition of transmission rates in heterogeneous, large-scale spatial systems.

  2. Attempt to determine the largest scale of primordial density perturbations in the universe

    Science.gov (United States)

    Berera, Arjun; Fang, Li-Zhi; Hinshaw, Gary

    1998-02-01

    The principle of causality requires that a pure power-law spectrum of cosmological density perturbations possess a super-Hubble suppression scale. We search for evidence of such suppression by performing a three parameter likelihood analysis of the COBE-DMR 4-year sky maps with respect to the amplitude, the spectral index, and the suppression scale. It is found that all suppression scales larger than c/H0 are consistent with the data, but that scales of order c/H0 are slightly preferred, at roughly the one-sigma level. Super-Hubble density fluctuations on very large scales (>>c/H0) can only be explained in the context of present theory by a de Sitter expansion phase, whereas those that are ``small'' (~c/H0) can also be explained within the standard hot big-bang model. Density perturbations originating after any conceivable de Sitter expansion phase or during non-isentropic de Sitter expansion have natural kinematic constraints which could explain a small super-Hubble suppression scale. Standard inflationary cosmology, which is characterized by isentropic de Sitter expansion, generically predicts that the particle horizon should be much larger than the present-day Hubble radius, c/H0. For such scenarios, a small super-Hubble suppression scale would require the duration of the inflation epoch to be fairly short. Suppression scales smaller than c/H0 are strongly excluded by the COBE data.

  3. Large-Scale Forest Modeling: Deducing Stand Density from Inventory Data

    Directory of Open Access Journals (Sweden)

    Oskar Franklin

    2012-01-01

    Full Text Available While effects of thinning and natural disturbances on stand density play a central role for forest growth, their representation in large-scale studies is restricted by both model and data availability. Here a forest growth model was combined with a newly developed generic thinning model to estimate stand density and site productivity based on widely available inventory data (tree species, age class, volume, and increment. The combined model successfully coupled biomass, increment, and stand closure (=stand density/self-thinning limited stand density, as indicated by cross-validation against European-wide inventory data. The improvement in model performance attained by including variable stand closure among age cohorts compared to a fixed closure suggests that stand closure is an important parameter for accurate forest growth modeling also at large scales.

  4. Predicting gully densities at sub-continental scales: a case study for the Horn of Africa

    Science.gov (United States)

    Vanmaercke, Matthias; Pelckmans, Ignace; Poesen, Jean

    2017-04-01

    Gully erosion is a major cause of land degradation in many regions, due to its negative impacts on catchment hydrology, its associated losses of land and damage to infrastructure, as well as its often major contributions to catchment sediment yields. Mitigation and prevention of gully erosion requires a good knowledge of its spatial patterns and controlling factors. However, our ability to simulate or predict this process remains currently very limited. This is especially the case for the regional scale. Whereas detailed case studies have provided important insights into the drivers of gully erosion at local scales, these findings are often difficult to upscale to larger regions. Here we utilized a simple and cheap method to predict patterns of gully density at the sub-continental scale. By means of a random sampling procedure, we mapped gully densities for over sixty study sites across the Horn of Africa, using freely available Google Earth imagery. Next, we statistically analyzed which factors best explained the observed variation in mapped gully density. Based on these findings, we constructed a multiple regression model that simulates gully density, based on topography (average slope), soil characteristics (percentage silt) and land use (NDVI-value). Although our model could benefit from further refinement, it succeeds already fairly well in simulating the patterns of gully density at sub-continental scales. Over 75% of the predicted gully densities differ less than 5% from the observed gully density, while over 90% of the predictions deviate less than 10%. Exploration of our results further showed that this methodology may be highly useful to quantify total gully erosion rates at regional and continental scales as well as the contribution of gully erosion to catchment sediment yields.

  5. Density-temperature scaling of the fragility in a model glass-former

    DEFF Research Database (Denmark)

    Schrøder, Thomas; Sengupta, Shiladitya; Sastry, Srikanth

    2013-01-01

    Dynamical quantities e.g. diffusivity and relaxation time for some glass-formers may depend on density and temperature through a specific combination, rather than independently, allowing the representation of data over ranges of density and temperature as a function of a single scaling variable...... of the activation free energy in the Adam-Gibbs relation, is consistent with the exponent values obtained by other means....

  6. Predicting above-ground density and distribution of small mammal prey species at large spatial scales.

    Science.gov (United States)

    Olson, Lucretia E; Squires, John R; Oakleaf, Robert J; Wallace, Zachary P; Kennedy, Patricia L

    2017-01-01

    Grassland and shrub-steppe ecosystems are increasingly threatened by anthropogenic activities. Loss of native habitats may negatively impact important small mammal prey species. Little information, however, is available on the impact of habitat variability on density of small mammal prey species at broad spatial scales. We examined the relationship between small mammal density and remotely-sensed environmental covariates in shrub-steppe and grassland ecosystems in Wyoming, USA. We sampled four sciurid and leporid species groups using line transect methods, and used hierarchical distance-sampling to model density in response to variation in vegetation, climate, topographic, and anthropogenic variables, while accounting for variation in detection probability. We created spatial predictions of each species' density and distribution. Sciurid and leporid species exhibited mixed responses to vegetation, such that changes to native habitat will likely affect prey species differently. Density of white-tailed prairie dogs (Cynomys leucurus), Wyoming ground squirrels (Urocitellus elegans), and leporids correlated negatively with proportion of shrub or sagebrush cover and positively with herbaceous cover or bare ground, whereas least chipmunks showed a positive correlation with shrub cover and a negative correlation with herbaceous cover. Spatial predictions from our models provide a landscape-scale metric of above-ground prey density, which will facilitate the development of conservation plans for these taxa and their predators at spatial scales relevant to management.

  7. A plausible interpretation of the density scaling of the diffusivity in viscous liquids

    OpenAIRE

    Papathanassiou, Anthony N.

    2010-01-01

    Fundamental thermodynamic concepts and an earlier elastic solid-state point defect model are employed to formulate an analytical second-order olynomial function describing the density scaling of the diffusion coefficient in viscous liquids. The scaling exponent is correlated, within the approximations made in the present approach, with the pressure derivative of the isothermal bulk modulus. Our findings are compared with computer simulation results.

  8. Large Scale Density Estimation of Blue and Fin Whales: Utilizing Sparse Array Data to Develop and Implement a New Method for Estimating Blue and Fin Whale Density

    Science.gov (United States)

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Large Scale Density Estimation of Blue and Fin Whales ...Utilizing Sparse Array Data to Develop and Implement a New Method for Estimating Blue and Fin Whale Density Len Thomas & Danielle Harris Centre...to develop and implement a new method for estimating blue and fin whale density that is effective over large spatial scales and is designed to cope

  9. Scaling of adult regional body mass and body composition as a whole to height: Relevance to body shape and body mass index.

    Science.gov (United States)

    Schuna, John M; Peterson, Courtney M; Thomas, Diana M; Heo, Moonseong; Hong, Sangmo; Choi, Woong; Heymsfield, Steven B

    2015-01-01

    Adult body mass (MB) empirically scales as height (Ht) squared (MB ∝ Ht(2) ), but does regional body mass and body composition as a whole also scale as Ht(2) ? This question is relevant to a wide range of biological topics, including interpretation of body mass index (BMI). Dual-energy X-ray absorptiometry (DXA) was used to quantify regional body mass [head (MH), trunk, arms, and legs] and whole-body composition [fat, lean soft tissue (LST), and bone mineral content (BMC)] in non-Hispanic (NH) white, NH black, Mexican American, and Korean adults participating in the National Health and Nutrition Examination Survey (NHANES; n = 17,126) and Korean NHANES (n = 8,942). Regression models were developed to establish Ht scaling powers for each measured component with adjustments for age and adiposity. Exploratory analyses revealed a consistent scaling pattern across men and women of the four population groups: regional mass powers, head (∼0.8-1) body composition, LST (∼2.0-2.3) body mass scaled uniformly across the eight sex and population groups as Ht(∼2) , tall and short subjects differed in body shape (e.g., MH/MB ∝ Ht(-∼1) ) and composition. Adult human body shape and relative composition are a function of body size as represented by stature, a finding that reveals a previously unrecognized phenotypic heterogeneity as defined by BMI. These observations provide new pathways for exploring mechanisms governing the interrelations between adult stature, body morphology, biomechanics, and metabolism. © 2014 Wiley Periodicals, Inc.

  10. Predicting above-ground density and distribution of small mammal prey species at large spatial scales

    Science.gov (United States)

    Lucretia E. Olson; John R. Squires; Robert J. Oakleaf; Zachary P. Wallace; Patricia L. Kennedy

    2017-01-01

    Grassland and shrub-steppe ecosystems are increasingly threatened by anthropogenic activities. Loss of native habitats may negatively impact important small mammal prey species. Little information, however, is available on the impact of habitat variability on density of small mammal prey species at broad spatial scales. We examined the relationship between small mammal...

  11. Vibrational frequency scale factors for density functional theory and the polarization consistent basis sets.

    Science.gov (United States)

    Laury, Marie L; Carlson, Matthew J; Wilson, Angela K

    2012-11-15

    Calculated harmonic vibrational frequencies systematically deviate from experimental vibrational frequencies. The observed deviation can be corrected by applying a scale factor. Scale factors for: (i) harmonic vibrational frequencies [categorized into low (1000 cm(-1))], (ii) vibrational contributions to enthalpy and entropy, and (iii) zero-point vibrational energies (ZPVEs) have been determined for widely used density functionals in combination with polarization consistent basis sets (pc-n, n = 0,1,2,3,4). The density functionals include pure functionals (BP86, BPW91, BLYP, HCTH93, PBEPBE), hybrid functionals with Hartree-Fock exchange (B3LYP, B3P86, B3PW91, PBE1PBE, mPW1K, BH&HLYP), hybrid meta functionals with the kinetic energy density gradient (M05, M06, M05-2X, M06-2X), a double hybrid functional with Møller-Plesset correlation (B2GP-PLYP), and a dispersion corrected functional (B97-D). The experimental frequencies for calibration were from 41 organic molecules and the ZPVEs for comparison were from 24 small molecules (diatomics, triatomics). For this family of basis sets, the scale factors for each property are more dependent on the functional selection than on basis set level, and thus allow for a suggested scale factor for each density functional when employing polarization consistent basis sets (pc-n, n = 1,2,3,4). A separate scale factor is recommended when the un-polarized basis set, pc-0, is used in combination with the density functionals.

  12. Variant Scaling Relationship for Mass-Density Across Tree-Dominated Communities

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The past few decades have seen a resurgence of interest in biological allometry. Specifically, a number of recent studies has suggested a -4/3 invariant scaling relationship between mass and density that is universally valid for tree-dominated communities, regardless of their phyletic affiliation or habitat. In the present study, we test this scaling relationship using a comprehensive forest biomass database, including 1 266 plots of six biomes and 17 forest types across China. The present study shows that the scaling exponent of the massdensity relationship varies across different tree-dominated communities and habitats. This great variability in the scaling exponent makes any generalization unwarranted. Although inappropriate regression methods can lead to flawed estimation of the scaling exponent, inconsistency of theoretical framework and empirical patterns may have undermined the validity of previous work.

  13. Theoretical uncertainty of the supersymmetric dark matter relic density from scheme and scale variations

    CERN Document Server

    Harz, J; Klasen, M; Kovarik, K; Steppeler, P

    2016-01-01

    For particle physics observables at colliders such as the LHC at CERN, it has been common practice for many decades to estimate the theoretical uncertainty by studying the variations of the predicted cross sections with a priori unpredictable scales. In astroparticle physics, this has so far not been possible, since most of the observables were calculated at Born level only, so that the renormalization scheme and scale dependence could not be studied in a meaningful way. In this paper, we present the first quantitative study of the theoretical uncertainty of the neutralino dark matter relic density from scheme and scale variations. We first explain in detail how the renormalization scale enters the tree-level calculations through coupling constants, masses and mixing angles. We then demonstrate a reduction of the renormalization scale dependence through one-loop SUSY-QCD corrections in many different dark matter annihilation channels and enhanced perturbative stability of a mixed on-shell/$\\bar{\\rm DR}$ renor...

  14. Large-Scale Density Functional Theory Transition State Searching in Enzymes.

    Science.gov (United States)

    Lever, Greg; Cole, Daniel J; Lonsdale, Richard; Ranaghan, Kara E; Wales, David J; Mulholland, Adrian J; Skylaris, Chris-Kriton; Payne, Mike C

    2014-11-06

    Linear-scaling quantum mechanical density functional theory calculations have been applied to study the rearrangement of chorismate to prephenate in large-scale models of the Bacillus subtilis chorismate mutase enzyme. By treating up to 2000 atoms at a consistent quantum mechanical level of theory, we obtain an unbiased, almost parameter-free description of the transition state geometry and energetics. The activation energy barrier is calculated to be lowered by 10.5 kcal mol(-1) in the enzyme, compared with the equivalent reaction in water, which is in good agreement with experiment. Natural bond orbital analysis identifies a number of active site residues that are important for transition state stabilization in chorismate mutase. This benchmark study demonstrates that linear-scaling density functional theory techniques are capable of simulating entire enzymes at the ab initio quantum mechanical level of accuracy.

  15. Density Fluctuation Spectrum of Solar Wind Turbulence between Ion and Electron Scales

    CERN Document Server

    Chen, C H K; Bonnell, J W; Mozer, F S; Bale, S D

    2012-01-01

    We present a measurement of the spectral index of density fluctuations between ion and electron scales in solar wind turbulence using the EFI instrument on the ARTEMIS spacecraft. The mean spectral index at 1 AU was found to be -2.75 +/- 0.06, steeper than predictions for pure whistler or kinetic Alfven wave turbulence, but consistent with previous magnetic field measurements. The steep spectra are also consistent with expectations of increased intermittency or damping of some of the turbulent energy over this range of scales. Neither the spectral index nor the flattening of the density spectra before ion scales were found to depend on the proximity to the pressure anisotropy instability thresholds, suggesting that they are features inherent to the turbulent cascade.

  16. An Accurate Flux Density Scale from 50 MHz to 50 GHz

    CERN Document Server

    Perley, R A

    2016-01-01

    The flux density scale of Perley and Butler (2013) is extended downwards to ~50 MHz by utilizing recent observations with the Karl G. Jansky Very Large Array (VLA) of 20 sources between 220 MHz and 48.1 GHz, and legacy VLA observations at 73.8 MHz. The derived spectral flux densities are placed on an absolute scale by utilizing the Baars et al. (1977) values of Cygnus A (3C405) for frequencies below 2 GHz, and the Mars-based polynomials for 3C286, 3C295, and 3C196 from Perley and Butler (2013) above 2 GHz. Polynomial expressions are presented for all 20 sources, with accuracy limited by the primary standards to 3 -- 5% over the entire frequency range. Corrections to the scales proposed by Perley and Butler (2013) and by Scaife and Heald (2012) are given.

  17. A sublinear-scaling approach to density-functional-theory analysis of crystal defects

    Science.gov (United States)

    Ponga, M.; Bhattacharya, K.; Ortiz, M.

    2016-10-01

    We develop a sublinear-scaling method, referred to as MacroDFT, for the study of crystal defects using ab-initio Density Functional Theory (DFT). The sublinear scaling is achieved using a combination of the Linear Scaling Spectral Gauss Quadrature method (LSSGQ) and a Coarse-Graining approach (CG) based on the quasi-continuum method. LSSGQ reformulates DFT and evaluates the electron density without computing individual orbitals. This direct evaluation is possible by recourse to Gaussian quadrature over the spectrum of the linearized Hamiltonian operator. Furthermore, the nodes and weights of the quadrature can be computed independently for each point in the domain. This property is exploited in CG, where fields of interest are computed at selected nodes and interpolated elsewhere. In this paper, we present the MacroDFT method, its parallel implementation and an assessment of convergence and performance by means of test cases concerned with point defects in magnesium.

  18. Density and Cavitating Flow Results from a Full-Scale Optical Multiphase Cryogenic Flowmeter

    Science.gov (United States)

    Korman, Valentin

    2007-01-01

    Liquid propulsion systems are hampered by poor flow measurements. The measurement of flow directly impacts safe motor operations, performance parameters as well as providing feedback from ground testing and developmental work. NASA Marshall Space Flight Center, in an effort to improve propulsion sensor technology, has developed an all optical flow meter that directly measures the density of the fluid. The full-scale sensor was tested in a transient, multiphase liquid nitrogen fluid environment. Comparison with traditional density models shows excellent agreement with fluid density with an error of approximately 0.8%. Further evaluation shows the sensor is able to detect cavitation or bubbles in the flow stream and separate out their resulting effects in fluid density.

  19. Enhanced current and power density of micro-scale microbial fuel cells with ultramicroelectrode anodes

    Science.gov (United States)

    Ren, Hao; Rangaswami, Sriram; Lee, Hyung-Sool; Chae, Junseok

    2016-09-01

    We present a micro-scale microbial fuel cell (MFC) with an ultramicroelectrode (UME) anode, with the aim of creating a miniaturized high-current/power-density converter using carbon-neutral and renewable energy sources. Micro-scale MFCs have been studied for more than a decade, yet their current and power densities are still an order of magnitude lower than those of their macro-scale counterparts. In order to enhance the current/power densities, we engineer a concentric ring-shaped UME, with a width of 20 μm, to facilitate the diffusion of ions in the vicinity of the micro-organisms that form biofilm on the UME. The biofilm extends approximately 15 μm from the edge of the UME, suggesting the effective biofilm area increases. Measured current/power densities per the effective area and the original anode area are 7.08  ±  0.01 A m-2 & 3.09  ±  0.04 W m-2 and 17.7  ±  0.03 A m-2 & 7.72  ±  0.09 W m-2, respectively. This is substantially higher than any prior work in micro-scale MFCs, and very close, or even higher, to that of macro-scale MFCs. A Coulombic efficiency, a measure of how efficiently an MFC harvests electrons from donor substrate, of 70%, and an energy conversion efficiency of 17% are marked, highlighting the micro-scale MFC as an attractive alternative within the existing energy conversion portfolio.

  20. Scale-wise evolution of rainfall probability density functions fingerprints the rainfall generation mechanism

    Science.gov (United States)

    Molini, Annalisa; Katul, Gabriel; Porporato, Amilcare

    2010-05-01

    Possible linkages between climatic fluctuations in rainfall at low frequencies and local intensity fluctuations within single storms is now receiving significant attention in climate change research. To progress on a narrower scope of this problem, the cross-scale probabilistic structure of rainfall intensity records collected over time scales ranging from hours to decades at sites dominated by either convective or frontal systems is investigated. Across these sites, intermittency buildup from slow to fast time-scales is analyzed in terms of its heavy tailed and asymmetric signatures in the scale-wise evolution of rainfall probability density functions (pdfs). The analysis demonstrates that rainfall records dominated by convective storms develop heavier-tailed power law pdfs across finer scales when compared with their frontal systems counterpart. A concomitant marked asymmetry buildup also emerges across finer time scales necessitating skewed probability laws for quantifying the scale-wise evolution of rainfall pdfs. A scale-dependent probabilistic description of such fat tails, peakedness and asymmetry appearance is proposed and tested by using a modified q-Gaussian model, able to describe the scale wise evolution of rainfall pdfs in terms of the nonextensivity parameter q, a lacunarity (intermittency) correction γ and a tail asymmetry coefficient c, also functions of q.

  1. CERN runners scale new heights

    CERN Multimedia

    2001-01-01

    On a bright and sunny 1 December last, a team from CERN lifted the honours for the company team event of Switzerland's most popular running race. The occasion was the 24th 'Course de l'Escalade'. Photo : Part of the field in the men's over-50 categories. Gordon Lee (IT) is in the white top, just behind the runner in yellow in the centre of the photo.

  2. Chinese Gymnasts Scale New Heights

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    ChineseGymnastsScaleNewHeightsDeligencehasitsrewards,theChineseteamdiscovers.THECHENESENationalGymnasticsTeamhaditsbestperfor...

  3. CERN runners scale new heights

    CERN Document Server

    2002-01-01

    Part of the field in the men's over-50 categories. Gordon Lee (IT) is in the white top, just behind the runner in yellow in the centre of the photo. On a bright and sunny 1 December last, a team from CERN lifted the honours for the company team event of Switzerland's most popular running race. The occasion was the 24th 'Course de l'Escalade'. The Escalade races wind through the narrow streets of Geneva's Old Town, lined with friends and well-wishers for the event. Since they began in 1978, they have become so popular that the Escalade now ranks among the largest popular running events in Europe. Some 19000 people aged from 5 to 85 donned running shoes to brave the crowds last December. Clearly, not all could run at once, so races by category started at 11am and continued until after 7pm. Distances ranged from about 2 km for the youngest children to 7.5 km for the men's categories. 100 or so runners, men and women, from the top international elite were invited for the race. CERN runners had a double reason t...

  4. Visualizing the large-$Z$ scaling of the kinetic energy density of atoms

    CERN Document Server

    Cancio, Antonio C

    2016-01-01

    The scaling of neutral atoms to large $Z$, combining periodicity with a gradual trend to homogeneity, is a fundamental probe of density functional theory, one that has driven recent advances in understanding both the kinetic and exchange-correlation energies. Although research focus is normally upon the scaling of energies, insights can also be gained from energy densities. We visualize the scaling of the positive-definite kinetic energy density (KED) in closed-shell atoms, in comparison to invariant quantities based upon the gradient and Laplacian of the density. We notice a striking fit of the KED within the core of any atom to a gradient expansion using both the gradient and the Laplacian, appearing as an asymptotic limit around which the KED oscillates. The gradient expansion is qualitatively different from that derived from first principles for a slowly-varying electron gas and is correlated with a nonzero Pauli contribution to the KED near the nucleus. We propose and explore orbital-free meta-GGA models...

  5. Large-scale simulations of spin-density-wave order in frustrated lattices

    Science.gov (United States)

    Barros, Kipton; Batista, Cristian; Chern, Gia-Wei

    We investigate spin-density-wave (SDW) phases within a generalized mean-field approximation. This approach incorporates the thermal fluctuations of SDW order and the development of short-range order above magnetic ordering temperatures Tc. Using a new Langevin dynamics method, we study mesoscale structures associated with triple- Q SDW states that are induced by Fermi surface nesting in triangular and kagome lattice Hubbard models. The core of our linear-scaling Langevin dynamics simulations is an efficient stochastic kernel polynomial method for computing the electron density matrix. We also investigate exotic phases above Tc arising from preformed magnetic moments.

  6. Hard scale dependent gluon density, saturation and forward-forward dijet production at the LHC

    CERN Document Server

    Kutak, Krzysztof

    2014-01-01

    We propose a method to introduce Sudakov effects to unintegrated gluon density promoting it to be hard scale dependent. The advantage of proposed approach is that it guarantees that the gluon density is positive definite and that on integrated level the Sudakov effects cancel. Besides that the method to introduce the Sudakov effects is convenient since it does not need evaluation of cross section in the process of imposing the effects. As a case study we apply the method to calculate angular correlations in production of forward-forward dijet and $R_{pA}$ ratio for p+p vs. p+Pb collision.

  7. Rural to urban population density scaling of crime and property transactions in English and Welsh Parliamentary Constituencies

    CERN Document Server

    Hanley, Quentin S; Ribeiro, Haroldo V

    2016-01-01

    Urban population scaling of resource use, creativity metrics, and human behaviors has been widely studied. These studies have not looked in detail at the full range of human environments which represent a continuum from the most rural to heavily urban. We examined monthly police crime reports and property transaction values across all 573 Parliamentary Constituencies in England and Wales, finding that scaling models based on population density provided a far superior framework to traditional population scaling. We found four types of scaling: i) non-urban scaling in which a single power law explained the relationship between the metrics and population density from the most rural to heavily urban environments, ii) accelerated scaling in which high population density was associated with an increase in the power-law exponent, iii) inhibited scaling where the urban environment resulted in a reduction in the power-law exponent but remained positive, and iv) collapsed scaling where transition to the high density en...

  8. Planar gradient coil design by scaling the spatial frequencies of minimum-inductance current density.

    Science.gov (United States)

    Lee, S Y; Park, B S; Yi, J H; Yi, W

    1997-11-01

    Gradient coil inductance has been remarkably reduced by the minimum-inductance design technique, which minimizes the magnetic energy stored by the gradient coil. The planar gradient coil designed by this technique, however, often has poor magnetic field linearity. Scaling the spatial frequencies of the current density function derived by this method, the magnetic field linearity of the planar gradient coil can be greatly improved with a small sacrifice of gradient coil inductance. A figure of merit of the planar gradient coil has been found to be improved by scaling the spatial frequencies.

  9. Effect of small scale density perturbations on the formation of dark matter halo profiles

    CERN Document Server

    Pilipenko, S V; Lukash, V N; Mikheeva, E V

    2012-01-01

    With help of a set of toy N-body models of dark halo formation we study the impact of small scale initial perturbations on the inner density profiles of haloes. We find a significant flattening of the inner slope $\\alpha={d \\log \\rho \\over d \\log r}$ to $\\alpha=-0.5$ in some range of scales and amplitudes of the perturbations (while in the case of absence of these perturbations the NFW profile with $\\alpha=-1$ is reproduced). This effect may be responsible for the formation of cuspless galactic haloes.

  10. Effect of small-scale density perturbations on the formation of dark matter halo profiles

    Science.gov (United States)

    Pilipenko, S. V.; Doroshkevich, A. G.; Lukash, V. N.; Mikheeva, E. V.

    2012-11-01

    With the help of a set of toy N-body models of dark halo formation, we study the impact of small-scale initial perturbations on the inner density profiles of haloes. We find a significant flattening of the inner slope ? to α=-0.5 in some range of scales and amplitudes of the perturbations (while in the case of absence of these perturbations, the Navarro-Frenk-White profile with α=-1 is reproduced). This effect may be responsible for the formation of cuspless galactic haloes.

  11. Effect of small scale density perturbations on the formation of dark matter halo profiles

    OpenAIRE

    Pilipenko, S. V.; Doroshkevich, A. G.; Lukash, V. N.; Mikheeva, E. V.

    2012-01-01

    With help of a set of toy N-body models of dark halo formation we study the impact of small scale initial perturbations on the inner density profiles of haloes. We find a significant flattening of the inner slope $\\alpha={d \\log \\rho \\over d \\log r}$ to $\\alpha=-0.5$ in some range of scales and amplitudes of the perturbations (while in the case of absence of these perturbations the NFW profile with $\\alpha=-1$ is reproduced). This effect may be responsible for the formation of cuspless galact...

  12. QTL Analysis of Spike Morphological Traits and Plant Height in Winter Wheat (Triticum aestivum L. Using a High-Density SNP and SSR-Based Linkage Map

    Directory of Open Access Journals (Sweden)

    Huijie Zhai

    2016-11-01

    Full Text Available Wheat yield can be enhanced by modifying the spike morphology and the plant height. In this study, a population of 191 F9 recombinant inbred lines (RILs was developed from a cross between two winter cultivars Yumai 8679 and Jing 411. A dense genetic linkage map with 10,816 markers was constructed by incorporating single nucleotide polymorphism (SNP and simple sequence repeat (SSR marker information. Five spike morphological traits and plant height were evaluated under nine environments for the RILs and parental lines, and the number of detected environmentally stable QTLs were 18 and 3, respectively. The 1RS/1BL (rye translocation increased both spike length and spikelet number with constant spikelet compactness. The QPht.cau-2D.1 was identical to gene Rht8, which decreased spike length without modifying spikelet number. Notably, four novel QTLs locating on chromosomes 1AS (QSc.cau-1A.1, 2DS (QSc.cau-2D.1 and 7BS (QSl.cau-7B.1 and QSl.cau-7B.2 were firstly identified in this study, which provide further insights into the genetic factors that shaped the spike morphology in wheat. Moreover, SNP markers tightly linked to previously reported QTLs will eventually facilitate future studies including their positional cloning or marker-assisted selection.

  13. Linear-scaling density functional theory using the projector augmented wave method

    Science.gov (United States)

    Hine, Nicholas D. M.

    2017-01-01

    Quantum mechanical simulation of realistic models of nanostructured systems, such as nanocrystals and crystalline interfaces, demands computational methods combining high-accuracy with low-order scaling with system size. Blöchl’s projector augmented wave (PAW) approach enables all-electron (AE) calculations with the efficiency and systematic accuracy of plane-wave pseudopotential calculations. Meanwhile, linear-scaling (LS) approaches to density functional theory (DFT) allow for simulation of thousands of atoms in feasible computational effort. This article describes an adaptation of PAW for use in the LS-DFT framework provided by the ONETEP LS-DFT package. ONETEP uses optimisation of the density matrix through in situ-optimised local orbitals rather than the direct calculation of eigenstates as in traditional PAW approaches. The method is shown to be comparably accurate to both PAW and AE approaches and to exhibit improved convergence properties compared to norm-conserving pseudopotential methods.

  14. Non-zero density-velocity consistency relations for large scale structures

    CERN Document Server

    Rizzo, Luca Alberto; Valageas, Patrick

    2016-01-01

    We present exact kinematic consistency relations for cosmological structures that do not vanish at equal times and can thus be measured in surveys. These rely on cross-correlations between the density and velocity, or momentum, fields. Indeed, the uniform transport of small-scale structures by long wavelength modes, which cannot be detected at equal times by looking at density correlations only, gives rise to a shift in the amplitude of the velocity field that could be measured. These consistency relations only rely on the weak equivalence principle and Gaussian initial conditions. They remain valid in the non-linear regime and for biased galaxy fields. They can be used to constrain non-standard cosmological scenarios or the large-scale galaxy bias.

  15. The scaling dimension of low lying Dirac eigenmodes and of the topological charge density

    Energy Technology Data Exchange (ETDEWEB)

    Aubin, C. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Bernard, C. [Department of Physics, Washington University, St. Louis, MO 63130 (United States); Gottlieb, Steven [Department of Physics, Indiana Univerity, Bloomington, IN 47405 (United States); Gregory, E.B. [Department of Physics, University of Arizona, Tucson, AZ 85721 (United States); Heller, Urs M. [American Physical Society, One Research Road, Box 9000, Ridge, NY 11961 (United States); Hetrick, J.E. [Physics Department, University of the Pacific, Stockton, CA 95211 (United States); Osborn, J.; Sugar, R. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Forcrand, Ph. de [Institute for Theoretical Physics, ETH Zuerich, CH-8093 Zurich (Switzerland); CERN, Theory Division, CH-1211 Geneva 23 (Switzerland); Jahn, O. [Center for Theoretical Physics, MIT, Cambridge, MA 02139 (United States)

    2005-03-15

    As a quantitative measure of localization, the inverse participation ratio of low lying Dirac eigenmodes and topological charge density is calculated on quenched lattices over a wide range of lattice spacings and volumes. Since different topological objects (instantons, vortices, monopoles, and artifacts) have different co-dimension, scaling analysis provides information on the amount of each present and their correlation with the localization of low lying eigenmodes.

  16. Theoretical uncertainty of the supersymmetric dark matter relic density from scheme and scale variations

    Science.gov (United States)

    Harz, J.; Herrmann, B.; Klasen, M.; Kovařík, K.; Steppeler, P.

    2016-06-01

    For particle physics observables at colliders such as the LHC at CERN, it has been common practice for many decades to estimate the theoretical uncertainty by studying the variations of the predicted cross sections with a priori unpredictable scales. In astroparticle physics, this has so far not been possible, since most of the observables were calculated at Born level only, so that the renormalization scheme and scale dependence could not be studied in a meaningful way. In this paper, we present the first quantitative study of the theoretical uncertainty of the neutralino dark matter relic density from scheme and scale variations. We first explain in detail how the renormalization scale enters the tree-level calculations through coupling constants, masses and mixing angles. We then demonstrate a reduction of the renormalization scale dependence through one-loop SUSY-QCD corrections in many different dark matter annihilation channels and enhanced perturbative stability of a mixed on-shell /DR ¯ renormalization scheme over a pure DR ¯ scheme in the top-quark sector. In the stop-stop annihilation channel, the Sommerfeld enhancement and its scale dependence are shown to be of particular importance. Finally, the impact of our higher-order SUSY-QCD corrections and their scale uncertainties are studied in three typical scenarios of the phenomenological minimal supersymmetric standard model with eleven parameters (pMSSM-11). We find that the theoretical uncertainty is reduced in many cases and can become comparable to the size of the experimental one in some scenarios.

  17. Milky Way Red Dwarfs in the BoRG Survey; Galactic scale-height and the distribution of dwarfs stars in WFC3 imaging

    CERN Document Server

    Holwerda, B W; Clarkson, W; Sahu, K; Bradley, L; Stiavelli, M; Pirzkal, N; De Marchi, G; Andersen, M; Bouwens, R; Ryan, R

    2014-01-01

    We present a tally of Milky Way late-type dwarf stars in 68 WFC3 pure-parallel fields (227 arcmin^2) from the Brightest of Reionizing Galaxies (BoRG) survey for high-redshift galaxies. Using spectroscopically identified M-dwarfs in two public surveys, the CANDELS and the ERS mosaics, we identify a morphological selection criterion using the half-light radius (r50), a near-infrared J-H, G-J color region where M-dwarfs are found, and a V-J relation with M-dwarf subtype. We apply this morphological selection of stellar objects, color-color selection of M-dwarfs and optical-near-infrared color subtyping to compile a catalog of 274 M-dwarfs belonging to the disk of the Milky Way with a limiting magnitude of m_F125W < 24. Based on the M-dwarfs statistics, we conclude that (a) the previously identified North/South discrepancy in M-dwarf numbers persists in our sample; there are more M-dwarfs in the Northern fields on average than in Southern ones, (b) the Milky Way's single disk scale-height for M-dwarfs is 0.3-4...

  18. A density spike on astrophysical scales from an N-field waterfall transition

    Directory of Open Access Journals (Sweden)

    Illan F. Halpern

    2015-09-01

    Full Text Available Hybrid inflation models are especially interesting as they lead to a spike in the density power spectrum on small scales, compared to the CMB, while also satisfying current bounds on tensor modes. Here we study hybrid inflation with N waterfall fields sharing a global SO(N symmetry. The inclusion of many waterfall fields has the obvious advantage of avoiding topologically stable defects for N>3. We find that it also has another advantage: it is easier to engineer models that can simultaneously (i be compatible with constraints on the primordial spectral index, which tends to otherwise disfavor hybrid models, and (ii produce a spike on astrophysically large length scales. The latter may have significant consequences, possibly seeding the formation of astrophysically large black holes. We calculate correlation functions of the time-delay, a measure of density perturbations, produced by the waterfall fields, as a convergent power series in both 1/N and the field's correlation function Δ(x. We show that for large N, the two-point function is 〈δt(xδt(0〉∝Δ2(|x|/N and the three-point function is 〈δt(xδt(yδt(0〉∝Δ(|x−y|Δ(|x|Δ(|y|/N2. In accordance with the central limit theorem, the density perturbations on the scale of the spike are Gaussian for large N and non-Gaussian for small N.

  19. Land-Use Scenarios: National-Scale Housing-Density Scenarios Consistent with Climate Change Storylines (Final Report)

    Science.gov (United States)

    EPA announced the availability of the final report, Land-Use Scenarios: National-Scale Housing-Density Scenarios Consistent with Climate Change Storylines. This report describes the scenarios and models used to generate national-scale housing density scenarios for the con...

  20. Parallel and Low-Order Scaling Implementation of Hartree-Fock Exchange Using Local Density Fitting.

    Science.gov (United States)

    Köppl, Christoph; Werner, Hans-Joachim

    2016-07-12

    Calculations using modern linear-scaling electron-correlation methods are often much faster than the necessary reference Hartree-Fock (HF) calculations. We report a newly implemented HF program that speeds up the most time-consuming step, namely, the evaluation of the exchange contributions to the Fock matrix. Using localized orbitals and their sparsity, local density fitting (LDF), and atomic orbital domains, we demonstrate that the calculation of the exchange matrix scales asymptotically linearly with molecular size. The remaining parts of the HF calculation scale cubically but become dominant only for very large molecular sizes or with many processing cores. The method is well parallelized, and the speedup scales well with up to about 100 CPU cores on multiple compute nodes. The effect of the local approximations on the accuracy of computed HF and local second-order Møller-Plesset perturbation theory energies is systematically investigated, and default values are established for the parameters that determine the domain sizes. Using these values, calculations for molecules with hundreds of atoms in combination with triple-ζ basis sets can be carried out in less than 1 h, with just a few compute nodes. The method can also be used to speed up density functional theory calculations with hybrid functionals that contain HF exchange.

  1. Molecular density functional theory of water describing hydrophobicity at short and long length scales.

    Science.gov (United States)

    Jeanmairet, Guillaume; Levesque, Maximilien; Borgis, Daniel

    2013-10-21

    We present an extension of our recently introduced molecular density functional theory of water [G. Jeanmairet et al., J. Phys. Chem. Lett. 4, 619 (2013)] to the solvation of hydrophobic solutes of various sizes, going from angstroms to nanometers. The theory is based on the quadratic expansion of the excess free energy in terms of two classical density fields: the particle density and the multipolar polarization density. Its implementation requires as input a molecular model of water and three measurable bulk properties, namely, the structure factor and the k-dependent longitudinal and transverse dielectric susceptibilities. The fine three-dimensional water structure around small hydrophobic molecules is found to be well reproduced. In contrast, the computed solvation free-energies appear overestimated and do not exhibit the correct qualitative behavior when the hydrophobic solute is grown in size. These shortcomings are corrected, in the spirit of the Lum-Chandler-Weeks theory, by complementing the functional with a truncated hard-sphere functional acting beyond quadratic order in density, and making the resulting functional compatible with the Van-der-Waals theory of liquid-vapor coexistence at long range. Compared to available molecular simulations, the approach yields reasonable solvation structure and free energy of hard or soft spheres of increasing size, with a correct qualitative transition from a volume-driven to a surface-driven regime at the nanometer scale.

  2. LARGE-SCALE VORTICAL STRUCTURES PRODUCED BY AN IMPINGING DENSITY JET IN SHALLOW CROSSFLOW

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The large-scale vortical structures produced by an impinging density jet in shallow crossflow were numerically investigated in detail using RNG turbulence model.The scales, formation mechanism and evolution feature of the upstream wall vortex in relation to stagnation point and the Scarf vortex in near field were analyzed. The computed characteristic scales of the upstream vortex show distinguished three-dimensionality and vary with the velocity ratio and the water depth. The Scarf vortex in the near field plays an important role in the lateral concentration distributions of the impinging jet in crossflow. When the velocity ratio is relatively small, there exists a distinct lateral high concentration aggregation zone at the lateral edge between the bottom layer wall jet and the ambient crossflow, which is dominated by the Scarf vortex in the near field.

  3. Simulations of Baryon Acoustic Oscillations I: Growth of Large-Scale Density Fluctuations

    CERN Document Server

    Takahashi, Ryuichi; Matsubara, Takahiko; Sugiyama, Naoshi; Kayo, Issha; Nishimichi, Takahiro; Shirata, Akihito; Taruya, Atsushi; Saito, Shun; Yahata, Kazuhiro; Suto, Yasushi

    2008-01-01

    We critically examine how well the evolution of large-scale density perturbations is followed in cosmological $N$-body simulations. We first run a large volume simulation and perform a mode-by-mode analysis in three-dimensional Fourier space. We show that the growth of large-scale fluctuations significantly deviates from linear theory predictions. The deviations are caused by {\\it nonlinear} coupling with a small number of modes at largest scales owing to finiteness of the simulation volume. We then develop an analytic model based on second-order perturbation theory to quantify the effect. Our model accurately reproduces the simulation results. For a single realization, the second-order effect appears typically as ``zig-zag'' patterns around the linear-theory prediction, which imprints artificial ``oscillations'' that lie on the real baryon-acoustic oscillations. Although an ensemble average of a number of realizations approaches the linear theory prediction, the dispersions of the realizations remain large e...

  4. Multi-scaling mix and non-universality between population and facility density

    Science.gov (United States)

    Qian, Jiang-Hai; Yang, Cheng-Hao; Han, Ding-Ding; Ma, Yu-Gang

    2012-11-01

    The distribution of facilities is closely related to our social economic activities. Recent studies have reported a scaling relation between population and facility density, with the exponent depending on the type of facility. In this paper, we show that generally this exponent is not universal for a specific type of facility. Instead, by using Chinese data, we find that it increases with per capita gross domestic product (GDP). Thus our observed scaling law is actually a mixture of several multi-scaling relations. This result indicates that facilities may change their public or commercial attributes according to the outside environment. We argue that this phenomenon results from an unbalanced regional economic level, and suggest a modification of a previous model by introducing the consuming capacity. The modified model reproduces most of our observed properties.

  5. Multi-scaling mix and non-universality between population and facility density

    CERN Document Server

    Qian, J H; Han, D D; Ma, Y G; 10.1016/j.physa.2012.05.038

    2012-01-01

    The distribution of facilities is closely related to our social economic activities. Recent studies have reported a scaling relation between population and facility density with the exponent depending on the type of facility. In this paper, we show that generally this exponent is not universal for a specific type of facility. Instead by using Chinese data we find that it increases with Per Capital GDP. Thus our observed scaling law is actually a mixture of some multi-scaling relations. This result indicates that facilities may change their public or commercial attributes according to the outside environment. We argue that this phenomenon results from the unbalanced regional economic level and suggest a modification for previous model by introducing consuming capacity. The modified model reproduces most of our observed properties.

  6. Modeling fence location and density at a regional scale for use in wildlife management.

    Directory of Open Access Journals (Sweden)

    Erin E Poor

    Full Text Available Barbed and woven wire fences, common structures across western North America, act as impediments to wildlife movements. In particular, fencing influences pronghorn (Antilocapra americana daily and seasonal movements, as well as modifying habitat selection. Because of fencing's impacts to pronghorn and other wildlife, it is a potentially important factor in both wildlife movement and habitat selection models. At this time, no geospatial fencing data is available at regional scales. Consequently, we constructed a regional fence model using a series of land tenure assumptions for the Hi-Line region of northern Montana--an area consisting of 13 counties over 103,400 km(2. Randomized 3.2 km long transects (n = 738 on both paved and unpaved roads were driven to collect information on habitat, fence densities and fence type. Using GIS, we constructed a fence location and a density model incorporating ownership, size, neighboring parcels, township boundaries and roads. Local knowledge of land ownership and land use assisted in improving the final models. We predict there is greater than 263,300 km of fencing in the Hi-Line region, with a maximum density of 6.8 km of fencing per km(2 and mean density of 2.4 km of fencing per km(2. Using field data to assess model accuracy, Cohen's Kappa was measured at 0.40. On-the-ground fence modification or removal could be prioritized by identifying high fence densities in critical wildlife areas such as pronghorn migratory pathways or sage grouse lekking habitat. Such novel fence data can assist wildlife and land managers to assess effects of anthropogenic features to wildlife at various scales; which in turn may help conserve declining grassland species and overall ecological functionality.

  7. Modeling fence location and density at a regional scale for use in wildlife management.

    Science.gov (United States)

    Poor, Erin E; Jakes, Andrew; Loucks, Colby; Suitor, Mike

    2014-01-01

    Barbed and woven wire fences, common structures across western North America, act as impediments to wildlife movements. In particular, fencing influences pronghorn (Antilocapra americana) daily and seasonal movements, as well as modifying habitat selection. Because of fencing's impacts to pronghorn and other wildlife, it is a potentially important factor in both wildlife movement and habitat selection models. At this time, no geospatial fencing data is available at regional scales. Consequently, we constructed a regional fence model using a series of land tenure assumptions for the Hi-Line region of northern Montana--an area consisting of 13 counties over 103,400 km(2). Randomized 3.2 km long transects (n = 738) on both paved and unpaved roads were driven to collect information on habitat, fence densities and fence type. Using GIS, we constructed a fence location and a density model incorporating ownership, size, neighboring parcels, township boundaries and roads. Local knowledge of land ownership and land use assisted in improving the final models. We predict there is greater than 263,300 km of fencing in the Hi-Line region, with a maximum density of 6.8 km of fencing per km(2) and mean density of 2.4 km of fencing per km(2). Using field data to assess model accuracy, Cohen's Kappa was measured at 0.40. On-the-ground fence modification or removal could be prioritized by identifying high fence densities in critical wildlife areas such as pronghorn migratory pathways or sage grouse lekking habitat. Such novel fence data can assist wildlife and land managers to assess effects of anthropogenic features to wildlife at various scales; which in turn may help conserve declining grassland species and overall ecological functionality.

  8. A community integration strategy based on an improved modularity density increment for large-scale networks

    Science.gov (United States)

    Shang, Ronghua; Zhang, Weitong; Jiao, Licheng; Stolkin, Rustam; Xue, Yu

    2017-03-01

    This paper presents a community integration strategy for large-scale networks, based on pre-partitioning, followed by optimization of an improved modularity density increment Δ D. Our proposed method initially searches for local core nodes in the network, i.e. potential community centers, and expands these communities to include neighbor nodes which have sufficiently high similarity with the core node. In this way, we can effectively exploit the information of the node and structure of the network, to accurately pre-partition the network into communities. Next, we arrange these pre-partitioned communities according to their external connections in descending order. In this way, we can ensure that communities with greater influence are prioritized during the process of community integration. At the same time, this paper proposes an improved modularity density increment Δ D, and shows how to use this as an objective function during the community integration optimization process. During the process of community consolidation, those neighbor communities with few external connections are prioritized for merging, thereby avoiding the fusion errors. Finally, we incorporate global reasoning into the process of local integration. We calculate and compare the improved modularity density increment of each pair of communities, to determine whether or not they should be integrated, effectively improve the accuracy of community integration. Experimental results show that our proposed algorithm can obtain superior community classification results on 5 large-scale networks, as compared with 8 other well known algorithms from the literature.

  9. A global scale picture of ionospheric peak electron density changes during geomagnetic storms

    Science.gov (United States)

    Kumar, Vickal V.; Parkinson, Murray L.

    2017-04-01

    Changes in ionospheric plasma densities can affect society more than ever because of our increasing reliance on communication, surveillance, navigation, and timing technology. Models struggle to predict changes in ionospheric densities at nearly all temporal and spatial scales, especially during geomagnetic storms. Here we combine a 50 year (1965-2015) geomagnetic disturbance storm time (Dst) index with plasma density measurements from a worldwide network of 132 vertical incidence ionosondes to develop a picture of global scale changes in peak plasma density due to geomagnetic storms. Vertical incidence ionosondes provide measurements of the critical frequency of the ionospheric F2 layer (foF2), a direct measure of the peak electron density (NmF2) of the ionosphere. By dissecting the NmF2 perturbations with respect to the local time at storm onset, season, and storm intensity, it is found that (i) the storm-associated depletions (negative storm effects) and enhancements (positive storm effects) are driven by different but related physical mechanisms, and (ii) the depletion mechanism tends to dominate over the enhancement mechanism. The negative storm effects, which are detrimental to HF radio links, are found to start immediately after geomagnetic storm onset in the nightside high-latitude ionosphere. The depletions in the dayside high-latitude ionosphere are delayed by a few hours. The equatorward expansion of negative storm effects is found to be regulated by storm intensity (farthest equatorward and deepest during intense storms), season (largest in summer), and time of day (generally deeper on the nightside). In contrast, positive storm effects typically occur on the dayside midlatitude and low-latitude ionospheric regions when the storms are in the main phase, regardless of the season. Closer to the magnetic equator, moderate density enhancements last up to 40 h during the recovery phase of equinox storms, regardless of the local time. Strikingly, high

  10. Experimental studies and computational benchmark on heavy liquid metal natural circulation in a full height-scale test loop for small modular reactors

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Yong-Hoon, E-mail: chaotics@snu.ac.kr [Department of Energy Systems Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of); Cho, Jaehyun [Korea Atomic Energy Research Institute, 111 Daedeok-daero, 989 Beon-gil, Yuseong-gu, Daejeon 34057 (Korea, Republic of); Lee, Jueun; Ju, Heejae; Sohn, Sungjune; Kim, Yeji; Noh, Hyunyub; Hwang, Il Soon [Department of Energy Systems Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of)

    2017-05-15

    Highlights: • Experimental studies on natural circulation for lead-bismuth eutectic were conducted. • Adiabatic wall boundaries conditions were established by compensating heat loss. • Computational benchmark with a system thermal-hydraulics code was performed. • Numerical simulation and experiment showed good agreement in mass flow rate. • An empirical relation was formulated for mass flow rate with experimental data. - Abstract: In order to test the enhanced safety of small lead-cooled fast reactors, lead-bismuth eutectic (LBE) natural circulation characteristics have been studied. We present results of experiments with LBE non-isothermal natural circulation in a full-height scale test loop, HELIOS (heavy eutectic liquid metal loop for integral test of operability and safety of PEACER), and the validation of a system thermal-hydraulics code. The experimental studies on LBE were conducted under steady state as a function of core power conditions from 9.8 kW to 33.6 kW. Local surface heaters on the main loop were activated and finely tuned by trial-and-error approach to make adiabatic wall boundary conditions. A thermal-hydraulic system code MARS-LBE was validated by using the well-defined benchmark data. It was found that the predictions were mostly in good agreement with the experimental data in terms of mass flow rate and temperature difference that were both within 7%, respectively. With experiment results, an empirical relation predicting mass flow rate at a non-isothermal, adiabatic condition in HELIOS was derived.

  11. Surface Density of dark matter haloes on galactic and cluster scales

    CERN Document Server

    Del Popolo, A; Belvedere, G

    2013-01-01

    In this paper, in the framework of the secondary infall model, the correlation between the central surface density and the halo core radius of galaxy, and cluster of galaxies, dark matter haloes was analyzed, this having recently been studied on a wide range of scales. We used Del Popolo (2009) secondary infall model taking into account ordered and random angular momentum, dynamical friction, and dark matter (DM) adiabatic contraction to calculate the density profile of haloes, and then these profiles are used to determine the surface density of DM haloes. The main result is that $r_\\ast$ (the halo characteristic radius) is not an universal quantity as claimed by Donato et al. (2009) and Gentile et al. (2009). On the contrary, we find a correlation with the halo mass $M_{200}$ in agreement with Cardone & Tortora (2010), Boyarsky at al. (2009) and Napolitano et al. (2010), but with a significantly smaller scatter, namely $0.16 \\pm 0.05$. We also consider the baryon column density finding this latter being ...

  12. Feeding strategies enhance high cell density cultivation and protein expression in milliliter scale bioreactors.

    Science.gov (United States)

    Faust, Georg; Janzen, Nils H; Bendig, Christoph; Römer, Lin; Kaufmann, Klaus; Weuster-Botz, Dirk

    2014-10-01

    Miniature bioreactors under parallel fed-batch operations are not only useful screening tools for bioprocess development but also provide a suitable basis for eventual scale-up. In this study, three feeding strategies were investigated: besides the established intermittent feeding by a liquid handler, an optimized microfluidic device and a new enzymatic release system were applied for parallel fed-batch cultivation of Escherichia coli HMS174(DE3) and BL21(DE3) strains in stirred-tank bioreactors on a 10 mL scale. Lower fluctuation in dissolved oxygen (DO) and higher optical densities were measured in fed-batch processes applying the microfluidic device or the enzymatic glucose/fructose release system (conversion of intermittently added sucrose by an invertase), but no difference in dry cell weights (DCW) were observed. With all three feeding strategies high cell densities were realized on a milliliter scale with final optical density measured at 600 nm (OD600 ) of 114-133 and final DCW concentrations of 69-70 g L(-1) . The effect of feeding strategies on the expression of two heterologous proteins was investigated. Whereas no impact was observed on the expression of the spider silk protein eADF4(C16), the fluorescence of enhanced green fluorescence protein (eGFP) was reproducibly lower, if an intermittent glucose feed was applied. Thus, the impact of feeding strategy on expression is strongly dependent on the E. coli strain and/or expressed protein. As a completely continuous feed supply is difficult to realize in miniature bioreactors, the enzymatic release approach from this study can be easily applied in all microfluidic system to reduce fluctuations of glucose supply and DO concentrations.

  13. Compatibility of separatrix density scaling for divertor detachment with H-mode pedestal operation in DIII-D

    Science.gov (United States)

    Leonard, A. W.; McLean, A. G.; Makowski, M. A.; Stangeby, P. C.

    2017-08-01

    The midplane separatrix density is characterized in response to variations in upstream parallel heat flux density and central density through deuterium gas injection. The midplane density is determined from a high spatial resolution Thomson scattering diagnostic at the midplane with power balance analysis to determine the separatrix location. The heat flux density is varied by scans of three parameters, auxiliary heating, toroidal field with fixed plasma current, and plasma current with fixed safety factor, q 95. The separatrix density just before divertor detachment onset is found to scale consistent with the two-point model when radiative dissipation is taken into account. The ratio of separatrix to pedestal density, n e,sep/n e,ped varies from  ⩽30% to  ⩾60% over the dataset, helping to resolve the conflicting scaling of core plasma density limit and divertor detachment onset. The scaling of the separatrix density at detachment onset is combined with H-mode power threshold scaling to obtain a scaling ratio of minimum n e,sep/n e,ped expected in future devices.

  14. Nonmonotonic Recursive Polynomial Expansions for Linear Scaling Calculation of the Density Matrix.

    Science.gov (United States)

    Rubensson, Emanuel H

    2011-05-10

    As it stands, density matrix purification is a powerful tool for linear scaling electronic structure calculations. The convergence is rapid and depends only weakly on the band gap. However, as will be shown in this letter, there is room for improvements. The key is to allow for nonmonotonicity in the recursive polynomial expansion. On the basis of this idea, new purification schemes are proposed that require only half the number of matrix-matrix multiplications compared to previous schemes. The speedup is essentially independent of the location of the chemical potential and increases with decreasing band gap.

  15. Scaling of maximum probability density functions of velocity and temperature increments in turbulent systems

    CERN Document Server

    Huang, Y X; Zhou, Q; Qiu, X; Shang, X D; Lu, Z M; Liu, and Y L

    2014-01-01

    In this paper, we introduce a new way to estimate the scaling parameter of a self-similar process by considering the maximum probability density function (pdf) of tis increments. We prove this for $H$-self-similar processes in general and experimentally investigate it for turbulent velocity and temperature increments. We consider turbulent velocity database from an experimental homogeneous and nearly isotropic turbulent channel flow, and temperature data set obtained near the sidewall of a Rayleigh-B\\'{e}nard convection cell, where the turbulent flow is driven by buoyancy. For the former database, it is found that the maximum value of increment pdf $p_{\\max}(\\tau)$ is in a good agreement with lognormal distribution. We also obtain a scaling exponent $\\alpha\\simeq 0.37$, which is consistent with the scaling exponent for the first-order structure function reported in other studies. For the latter one, we obtain a scaling exponent $\\alpha_{\\theta}\\simeq0.33$. This index value is consistent with the Kolmogorov-Ob...

  16. DGDFT: A Massively Parallel Method for Large Scale Density Functional Theory Calculations

    CERN Document Server

    Hu, Wei; Yang, Chao

    2015-01-01

    We describe a massively parallel implementation of the recently developed discontinuous Galerkin density functional theory (DGDFT) [J. Comput. Phys. 2012, 231, 2140] method, for efficient large-scale Kohn-Sham DFT based electronic structure calculations. The DGDFT method uses adaptive local basis (ALB) functions generated on-the-fly during the self-consistent field (SCF) iteration to represent the solution to the Kohn-Sham equations. The use of the ALB set provides a systematic way to improve the accuracy of the approximation. It minimizes the number of degrees of freedom required to represent the solution to the Kohn-Sham problem for a desired level of accuracy. In particular, DGDFT can reach the planewave accuracy with far fewer numbers of degrees of freedom. By using the pole expansion and selected inversion (PEXSI) technique to compute electron density, energy and atomic forces, we can make the computational complexity of DGDFT scale at most quadratically with respect to the number of electrons for both i...

  17. DGDFT: A massively parallel method for large scale density functional theory calculations

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Wei, E-mail: whu@lbl.gov; Yang, Chao, E-mail: cyang@lbl.gov [Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Lin, Lin, E-mail: linlin@math.berkeley.edu [Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Mathematics, University of California, Berkeley, California 94720 (United States)

    2015-09-28

    We describe a massively parallel implementation of the recently developed discontinuous Galerkin density functional theory (DGDFT) method, for efficient large-scale Kohn-Sham DFT based electronic structure calculations. The DGDFT method uses adaptive local basis (ALB) functions generated on-the-fly during the self-consistent field iteration to represent the solution to the Kohn-Sham equations. The use of the ALB set provides a systematic way to improve the accuracy of the approximation. By using the pole expansion and selected inversion technique to compute electron density, energy, and atomic forces, we can make the computational complexity of DGDFT scale at most quadratically with respect to the number of electrons for both insulating and metallic systems. We show that for the two-dimensional (2D) phosphorene systems studied here, using 37 basis functions per atom allows us to reach an accuracy level of 1.3 × 10{sup −4} Hartree/atom in terms of the error of energy and 6.2 × 10{sup −4} Hartree/bohr in terms of the error of atomic force, respectively. DGDFT can achieve 80% parallel efficiency on 128,000 high performance computing cores when it is used to study the electronic structure of 2D phosphorene systems with 3500-14 000 atoms. This high parallel efficiency results from a two-level parallelization scheme that we will describe in detail.

  18. The dynamical masses, densities, and star formation scaling relations of Lyα galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Rhoads, James E.; Malhotra, Sangeeta; Richardson, Mark L. A.; McLinden, Emily M. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Finkelstein, Steven L. [Department of Astronomy, University of Texas at Austin, 1 University Station C1400, Austin, TX 78712 (United States); Fynbo, Johan P. U. [DARK Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen Ø (Denmark); Tilvi, Vithal S., E-mail: James.Rhoads@asu.edu [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics, Texas A and M University, College Station, TX 77843 (United States)

    2014-01-01

    We present the first dynamical mass measurements for Lyα galaxies at high redshift, based on velocity dispersion measurements from rest-frame optical emission lines and size measurements from Hubble Space Telescope imaging, for nine galaxies drawn from four surveys. We use these measurements to study Lyα galaxies in the context of galaxy scaling relations. The resulting dynamical masses range from 10{sup 9} to 10{sup 10} M {sub ☉}. We also fit stellar population models to our sample and use them to place the Lyα sample on a stellar mass versus line width relation. The Lyα galaxies generally follow the same scaling relation as star-forming galaxies at lower redshift, although, lower stellar mass fits are also acceptable in ∼1/3 of the Lyα galaxies. Using the dynamical masses as an upper limit on gas mass, we show that Lyα galaxies have unusually active star formation for their gas mass surface density. This behavior is consistent with what is observed in starburst galaxies, despite the typically smaller masses and sizes of the Lyα galaxy population. Finally, we examine the mass densities of these galaxies and show that their future evolution likely requires dissipational ('wet') merging. In short, we find that Lyα galaxies are low-mass cousins of larger starbursts.

  19. Simulation of electron energy loss spectra of nanomaterials with linear-scaling density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Tait, E. W.; Ratcliff, L. E.; Payne, M. C.; Haynes, P. D.; Hine, N. D. M.

    2016-04-20

    Experimental techniques for electron energy loss spectroscopy (EELS) combine high energy resolution with high spatial resolution. They are therefore powerful tools for investigating the local electronic structure of complex systems such as nanostructures, interfaces and even individual defects. Interpretation of experimental electron energy loss spectra is often challenging and can require theoretical modelling of candidate structures, which themselves may be large and complex, beyond the capabilities of traditional cubic-scaling density functional theory. In this work, we present functionality to compute electron energy loss spectra within the onetep linear-scaling density functional theory code. We first demonstrate that simulated spectra agree with those computed using conventional plane wave pseudopotential methods to a high degree of precision. The ability of onetep to tackle large problems is then exploited to investigate convergence of spectra with respect to supercell size. Finally, we apply the novel functionality to a study of the electron energy loss spectra of defects on the (1 0 1) surface of an anatase slab and determine concentrations of defects which might be experimentally detectable.

  20. Scaling properties of information-theoretic quantities in density functional reactivity theory.

    Science.gov (United States)

    Rong, Chunying; Lu, Tian; Ayers, Paul W; Chattaraj, Pratim K; Liu, Shubin

    2015-02-21

    Density functional reactivity theory (DFRT) employs the electron density and its related quantities to describe reactivity properties of a molecular system. Quantities from information theory such as Shannon entropy, Fisher information, and Ghosh-Berkowitz-Parr entropy are natural descriptors within the DFRT framework. They have been previously employed to quantify electrophilicity, nucleophilicity and the steric effect. In this work, we examine their scaling properties with respect to the total number of electrons. To that end, we considered their representations in terms of both the electron density and the shape function for isolated atoms and neutral molecules. We also investigated their atomic behaviors in different molecules with three distinct partitioning schemes: Bader's zero-flux, Becke's fuzzy atom, and Hirshfeld's stockholder partitioning. Strong linear relationships of these quantities as a function of the total electron population are reported for atoms, molecules, and atoms in molecules. These relationships reveal how these information-theoretic quantities depend on the molecular environment and the electron population. These trends also indicate how these quantities can be used to explore chemical reactivity for real chemical processes.

  1. Missing baryons traced by the galaxy luminosity density in the large-scale WHIM filaments

    CERN Document Server

    Nevalainen, J; Liivamägi, L J; Branchini, E; Roncarelli, M; Giocoli, C; Heinämäki, P; Saar, E; Tamm, A; Finoguenov, A; Nurmi, P; Bonamente, M

    2015-01-01

    We propose a new approach to the missing baryons problem. Building on the common assumption that the missing baryons are in the form of the Warm Hot Intergalactic Medium (WHIM), we further assumed here that the galaxy luminosity density can be used as a tracer of the WHIM. The latter assumption is supported by our finding of a significant correlation between the WHIM density and the galaxy luminosity density in the hydrodynamical simulations of Cui et al. (2012). We further found that the fraction of the gas mass in the WHIM phase is substantially (by a factor of $\\sim$1.6) higher within the large scale galactic filaments, i.e. $\\sim$70\\%, compared to the average in the full simulation volume of $\\sim$0.1\\,Gpc$^3$. The relation between the WHIM overdensity and the galaxy luminosity overdensity within the galactic filaments is consistent with linear: $\\delta_{\\rm whim}\\,=\\,0.7\\,\\pm\\,0.1\\,\\times\\,\\delta_\\mathrm{LD}^{0.9 \\pm 0.2}$. We applied our procedure to the line of sight to the blazar H2356-309 and found e...

  2. A turnkey data logger program for field-scale energy flux density measurements using eddy covariance and surface renewal

    Science.gov (United States)

    Micrometeorological methods and ecosystem-scale energy and mass flux density measurements have become increasingly important in soil, agricultural, and environmental sciences. For many scientists without formal training in atmospheric science, these techniques are relatively inaccessible. Eddy cov...

  3. Roles of Spatial Scale and Rarity on the Relationship between Butterfly Species Richness and Human Density in South Africa

    National Research Council Canada - National Science Library

    Mecenero, Silvia; Altwegg, Res; Colville, Jonathan F; Beale, Colin M

    2015-01-01

    .... Species richness is often positively correlated with human population density at broad scales, but this correlation could also be caused by unequal sampling effort leading to higher species tallies...

  4. Fear of heights and visual height intolerance.

    Science.gov (United States)

    Brandt, Thomas; Huppert, Doreen

    2014-02-01

    The aim of this review is, first, to cover the different aspects of visual height intolerance such as historical descriptions, definition of terms, phenomenology of the condition, neurophysiological control of gaze, stance and locomotion, and therapy, and, second, to identify warranted epidemiological and experimental studies. Vivid descriptions of fear of heights can be found in ancient texts from the Greek, Roman, and Chinese classics. The life-time prevalence of visual height intolerance is as high as 28% in the general population, and about 50% of those who are susceptible report an impact on quality of life. When exposed to heights, visual exploration by eye and head movements is restricted, and the velocity of locomotion is reduced. Therapy for fear of heights is dominated by the behavioral techniques applied during real or virtual reality exposure. Their efficacy might be facilitated by the administration of D-cycloserine or glucocorticoids. Visual height intolerance has a considerable impact on daily life and interpersonal interactions. It is much more frequent than fear of heights, which is defined as an environmental subtype of a specific phobia. There is certainly a continuum stretching from acrophobia to a less-pronounced visual height intolerance, to which the categorical distinction of a specific phobia does not apply.

  5. Large-scale all-electron density functional theory calculations using an enriched finite element basis

    CERN Document Server

    Kanungo, Bikash

    2016-01-01

    We present a computationally efficient approach to perform large-scale all-electron density functional theory calculations by enriching the classical finite element basis with compactly supported atom-centered numerical basis functions that are constructed from the solution of the Kohn-Sham (KS) problem for single atoms. We term these numerical basis functions as enrichment functions, and the resultant basis as the enriched finite element basis. The enrichment functions are compactly supported through the use of smooth cutoff functions, which enhances the conditioning and maintains the locality of the basis. The integrals involved in the evaluation of the discrete KS Hamiltonian and overlap matrix in the enriched finite element basis are computed using an adaptive quadrature grid based on the characteristics of enrichment functions. Further, we propose an efficient scheme to invert the overlap matrix by using a block-wise matrix inversion in conjunction with special reduced-order quadrature rules to transform...

  6. Nearest neighbor density ratio estimation for large-scale applications in astronomy

    Science.gov (United States)

    Kremer, J.; Gieseke, F.; Steenstrup Pedersen, K.; Igel, C.

    2015-09-01

    In astronomical applications of machine learning, the distribution of objects used for building a model is often different from the distribution of the objects the model is later applied to. This is known as sample selection bias, which is a major challenge for statistical inference as one can no longer assume that the labeled training data are representative. To address this issue, one can re-weight the labeled training patterns to match the distribution of unlabeled data that are available already in the training phase. There are many examples in practice where this strategy yielded good results, but estimating the weights reliably from a finite sample is challenging. We consider an efficient nearest neighbor density ratio estimator that can exploit large samples to increase the accuracy of the weight estimates. To solve the problem of choosing the right neighborhood size, we propose to use cross-validation on a model selection criterion that is unbiased under covariate shift. The resulting algorithm is our method of choice for density ratio estimation when the feature space dimensionality is small and sample sizes are large. The approach is simple and, because of the model selection, robust. We empirically find that it is on a par with established kernel-based methods on relatively small regression benchmark datasets. However, when applied to large-scale photometric redshift estimation, our approach outperforms the state-of-the-art.

  7. Risk of large-scale evacuation based on the effectiveness of rescue strategies under different crowd densities.

    Science.gov (United States)

    Wang, Jinghong; Lo, Siuming; Wang, Qingsong; Sun, Jinhua; Mu, Honglin

    2013-08-01

    Crowd density is a key factor that influences the moving characteristics of a large group of people during a large-scale evacuation. In this article, the macro features of crowd flow and subsequent rescue strategies were considered, and a series of characteristic crowd densities that affect large-scale people movement, as well as the maximum bearing density when the crowd is extremely congested, were analyzed. On the basis of characteristic crowd densities, the queuing theory was applied to simulate crowd movement. Accordingly, the moving characteristics of the crowd and the effects of typical crowd density-which is viewed as the representation of the crowd's arrival intensity in front of the evacuation passageways-on rescue strategies was studied. Furthermore, a "risk axle of crowd density" is proposed to determine the efficiency of rescue strategies in a large-scale evacuation, i.e., whether the rescue strategies are able to effectively maintain or improve evacuation efficiency. Finally, through some rational hypotheses for the value of evacuation risk, a three-dimensional distribution of the evacuation risk is established to illustrate the risk axle of crowd density. This work aims to make some macro, but original, analysis on the risk of large-scale crowd evacuation from the perspective of the efficiency of rescue strategies. © 2012 Society for Risk Analysis.

  8. Scaling behavior of chiral phase transition in two-flavor QCD with improved Wilson quarks at finite density

    CERN Document Server

    Ejiri, S; Aoki, S; Kanaya, K; Ohno, H; Saito, H; Hatsuda, T; Maezawa, Y; Umeda, T

    2010-01-01

    We study scaling behavior of a chiral order parameter performing a simulation of two-flavor QCD with improved Wilson quarks. It has been shown that the scaling behavior of the chiral order parameter defined by a Ward-Takahashi identity agrees with the scaling function of the three-dimensional O(4) spin model at zero chemical potential. We extend the scaling study to finite density QCD. Calculating derivatives of the chiral order parameter with respect to the chemical potential in two-flavor QCD, the scaling property of chiral phase transition is discussed in the low density region. We moreover calculate the curvature of the phase boundary of the chirl phase transition in the temperature and chemical potential plane assuming the O(4) scaling relation.

  9. Nanometer scale mapping of the density of states in an inhomogeneous superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Cren, T.; Roditchev, D.; Sacks, W.; Klein, J. [Univ. Paris 7 et Paris 6 (France). Groupe de Physique des Solides

    2001-04-01

    Using high-speed scanning tunneling spectroscopy (STS), we perform a full mapping of the quasiparticle density of states (DOS) in single crystals of Bi{sub 2-x}Pb{sub x}Sr{sub 2}CaCu{sub 2}0{sub 8+{delta}}. The measurements carried out at 5 K showed a complex spatial pattern of important variations of the local DOS on the nanometer scale. Superconducting areas, characterized by a well-pronounced superconducting gap, are coexisting with regions of a peakless gap structure which we attribute to the pseudogap. Within the large superconducting regions, the spectra reveal strong peak/dip/hump signatures, identical to the pristine Bi{sub 2}Sr{sub 2}CaCu{sub 2}0{sub 8+{delta}} case. On the contrary, in very small superconducting regions this fine structure is attenuated. Such a behavior of the local DOS suggests that the peak/dip/hump fine structure is not only a consequence of the superconducting state, but is also directly related to the scale of the phase coherence. The role of Bi-Pb substitutional disorder is discussed. (orig.)

  10. [Height vertigo, fear of heights, acrophobia].

    Science.gov (United States)

    Rennert, H

    1990-06-01

    Height vertigo (acrophobia) is a very frequent phenomenon being of interest for its physiological and psychological background, though usually only of limited significance in neuropsychiatry and otology. The different aspects as to its nature and origin are discussed. If acrophobia has developed into a conditioned reaction of avoidance with pressure of suffering, or acrophobia in persons, who have to work at heights, behavior therapeutic measures with systematic desensibilisation, starting from an imaginative training, are indicated.

  11. Power spectral density and scaling exponent of high frequency global solar radiation sequences

    Science.gov (United States)

    Calif, Rudy; Schmitt, François G.; Huang, Yongxiang

    2013-04-01

    invariance: Iq(f) ~ f-?(q) , ?(q) is the scaling exponent. This allows to characterize the scaling behavior of a process: fractal or multifractal with intermittent properties. For q = 2, the Hilbert spectrum is defined. In this work, The data are collected at the University site of Guadeloupe, an island in the West Indies, located at 16°15 N latitude 60°30 W longitude. Our measurements sampled at 1 Hz were performed during one year period. The analyzed data present a power spectral density E(f) displaying a power law of the form E(f) ~ f-β with 1.6 ˜ β ˜ 2.2 for frequencies f ˜ 0.1 Hz, corresponding to time scales T × 10 s. Furthermore, global solar radiation data possesses multifractal properties. For comparison, other multifractal analysis techniques such as structure functions, MDFA, wavelet leaders are also used. This preliminary work set the basis for further investigation dedicated to simulate and forecast a sequence of solar energy fluctuation under different meteorological conditions, in the multifractal framework.

  12. CLIMATIC SIGNALS FROM INTRA-ANNUAL DENSITY FLUCTUATION FREQUENCY IN MEDITERRANEAN PINES AT A REGIONAL SCALE

    Directory of Open Access Journals (Sweden)

    Enrica eZalloni

    2016-05-01

    Full Text Available Tree rings provide information about the climatic conditions during the growing season by recording them in different anatomical features, such as Intra-Annual Density Fluctuations (IADFs. IADFs are intra-annual changes of wood density appearing as latewood-like cells within earlywood, or earlywood-like cells within latewood. The occurrence of IADFs is dependent on the age and size of the tree, and it is triggered by climatic drivers. The variations of IADF frequency of different species and their dependence on climate across a wide geographical range have still to be explored. The objective of this study is to investigate the effect of age, tree-ring width and climate on IADF formation and frequency at a regional scale across the Mediterranean Basin in Pinus halepensis Mill., Pinus pinaster Ait. and Pinus pinea L. The analyzed tree-ring network was composed of P. pinea trees growing at 11 sites (2 in Italy, 4 in Spain and 4 in Portugal, P. pinaster from 19 sites (2 in Italy, 13 in Spain and 4 in Portugal, and P. halepensis from 38 sites in Spain. The correlations between IADF frequency and monthly minimum, mean and maximum temperatures, as well as between IADF frequency and total precipitation, were analyzed. A significant negative relationship between IADF frequency and tree-ring age was found for the three Mediterranean pines. Moreover, IADFs were more frequent in wider rings than in narrower ones, although the widest rings showed a reduced IADF frequency. Wet conditions during late summer/early autumn triggered the formation of IADFs in the three species. Our results suggest the existence of a common climatic driver for the formation of IADFs in Mediterranean pines, highlighting the potential use of IADF frequency as a proxy for climate reconstructions with geographical resolution.

  13. Small scale density variations of electrons and charged particles in the vicinity of polar mesosphere summer echoes

    Directory of Open Access Journals (Sweden)

    M. Rapp

    2003-01-01

    Full Text Available We present small scale variations of electron number densities and particle charge number densities measured in situ in the presence of polar mesosphere summer echoes. It turns out that the small scale fluctuations of electrons and negatively charged particles show a strong anticorrelation down to the smallest scales observed. Comparing these small scale structures with the simultaneously measured radar signal to noise profile, we find that the radar profile is well described by the power spectral density of both electrons and charged particles at the radar half wavelength (=the Bragg scale. Finally, we consider the shape of the power spectra of the observed plasma fluctuations and find that both charged particles and electrons show spectra that can be explained in terms of either neutral air turbulence acting on the distribution of a low diffusivity tracer or the fossil remnants of a formerly active turbulent region. All these results are consistent with the theoretical ideas by Rapp and Lübken (2003 suggesting that PMSE can be explained by a combination of active and fossil neutral air turbulence acting on the large and heavy charged aerosol particles which are subsequently mirrored in the electron number density distribution that becomes visible to a VHF radar when small scale fluctuations are present.

  14. 防治松褐天牛诱木设置密度及胸径大小试验%Monochamus alternatus Prevention Induced Diameter at Breast Height Wood Density and Size Settings Test

    Institute of Scientific and Technical Information of China (English)

    付甫永; 王健; 司徒春南

    2009-01-01

    研究了3种不同规格胸径的诱木在每公顷设置1、3、5和10株诱木的林分内诱集松褐天牛的效果.采用在林内均匀挂设诱捕器作对照,同一面积内设置不同密度和不同胸径的诱木作对比试验,观察记录诱捕器诱捕成虫和诱木诱集幼虫的情况,分析总结了不同密度下的3种胸径诱木的诱集幼虫效果,提出了按胸径5~15 cm和每公顷3株的密度设置诱木防治松材线虫病的传媒昆虫松褐天牛效果最佳.%Studied three different specifications of the induced tree diameter at breast height per hectare set in 1,3,5 and 10 induced wood stands Monochamus alternatus trapping effect, the use of uniform hanging in the forest set traps for the control, the same area of different density and different diameter of the wood induced contrast tests, observation of adult traps and trap trees induced trapping of the larvae, the analysis summed up in three different densities of wood diameter induced larvae trapping effect, put forward a by 5-15 cm diameter and 3 per hectare, the density of wood set induced pine wilt disease prevention and control of the media of insect Monochamus alternatus best.

  15. Transect-scale imaging of root zone electrical conductivity by inversion of multiple-height EMI measurements under different salinity conditions

    Science.gov (United States)

    Piero Deidda, Gian; Coppola, Antonio; Dragonetti, Giovanna; Comegna, Alessandro; Rodriguez, Giuseppe; Vignoli, Giulio

    2017-04-01

    The ability to determine the effects of salts on soils and plants, are of great importance to agriculture. To control its harmful effects, soil salinity needs to be monitored in space and time. This requires knowledge of its magnitude, temporal dynamics, and spatial variability. Soil salinity can be evaluated by measuring the bulk electrical conductivity (σb) in the field. Measurements of σb can be made with either in situ or remote devices (Rhoades and Oster, 1986; Rhoades and Corwin, 1990; Rhoades and Miyamoto, 1990). Time Domain Reflectometry (TDR) sensors allow simultaneous measurements of water content, θ, and σb. They may be calibrated in the laboratory for estimating the electrical conductivity of the soil solution (σw). However, they have a relatively small observation volume and thus they only provide local-scale measurements. The spatial range of the sensors is limited to tens of centimeters and extension of the information to a large area can be problematic. Also, information on the vertical distribution of the σb soil profile may only be obtained by installing sensors at different depths. In this sense, the TDR may be considered as an invasive technique. Compared to the TDR, non-invasive electromagnetic induction (EMI) techniques can be used for extensively mapping the bulk electrical conductivity in the field. The problem is that all these techniques give depth-weighted apparent electrical conductivity (ECa) measurements, depending on the specific depth distribution of the σb, as well as on the depth response function of the sensor used. In order to deduce the actual distribution of local σb in the soil profile, one may invert the signal coming from EMI sensors. Most studies use the linear model proposed by McNeill (1980), describing the relative depth-response of the ground conductivity meter. By using the forward linear model of McNeill, Borchers et al. (1997) implemented a Least Squares inverse procedure with second order Tikhonov

  16. Emergent Lifshitz scaling from N=4 SYM with supersymmetric heavy-quark density

    CERN Document Server

    Faedo, Anton F; Kumar, S Prem

    2014-01-01

    We consider supersymmetric configurations in Type IIB supergravity obtained by the beackreaction of fundamental strings ending on a stack of D3-branes and smeared uniformly in the three spatial directions along the D3-branes. These automatically include a distribution of D5-brane baryon vertices necessary to soak up string charge. The backgrounds are static, preserving eight supersymmetries, an SO(5) global symmetry and symmetry under spatial translations and rotations. We obtain the most general BPS configurations consistent with the symmetries. We show that the solutions to the Type IIB field equations are completely specified by a single function (the dilaton) satisfying a Poisson-like equation in two dimensions. We further find that the equation admits a class of solutions displaying Lifshitz-like scaling with dynamical critical exponent z=7. The equations also admit an asymptotically AdS_5 x S^5 solution deformed by the presence of backreacted string sources that yield a uniform density of heavy quarks i...

  17. Large-Scale Fluctuations in the Number Density of Galaxies in Independent Surveys of Deep Fields

    CERN Document Server

    Shirokov, S I; Baryshev, Yu V; Gorokhov, V L

    2016-01-01

    New arguments supporting the reality of large-scale fluctuations in the density of the visible matter in deep galaxy surveys are presented. A statistical analysis of the radial distributions of galaxies in the COSMOS and HDF-N deep fields is presented. Independent spectral and photometric surveys exist for each field, carried out in different wavelength ranges and using different observing methods. Catalogs of photometric redshifts in the optical (COSMOS-Zphot) and infrared (UltraVISTA) were used for the COSMOS field in the redshift interval $0.1 < z < 3.5$, as well as the zCOSMOS (10kZ) spectroscopic survey and the XMM-COSMOS and ALHAMBRA-F4 photometric redshift surveys. The HDFN-Zphot and ALHAMBRA-F5 catalogs of photometric redshifts were used for the HDF-N field. The Pearson correlation coefficient for the fluctuations in the numbers of galaxies obtained for independent surveys of the same deep field reaches $R = 0.70 \\pm 0.16$. The presence of this positive correlation supports the reality of fluctu...

  18. Parameter scaling toward high-energy density in a quasi-steady flow Z-pinch

    Science.gov (United States)

    Hughes, M. C.; Shumlak, U.; Nelson, B. A.; Golingo, R. P.; Claveau, E. L.; Doty, S. A.; Forbes, E. G.; Kim, B.; Ross, M. P.

    2016-10-01

    Sheared axial flows are utilized by the ZaP Flow Z-Pinch Experiment to stabilize MHD instabilities. The pinches formed are 50 cm long with radii ranging from 0.3 to 1.0 cm. The plasma is generated in a coaxial acceleration region, similar to a Marshall gun, which provides a steady supply of plasma for approximately 100 us. The power to the plasma is partially decoupled between the acceleration and pinch assembly regions through the use of separate power supplies. Adiabatic scaling of the Bennett relation gives targets for future devices to reach high-energy density conditions or fusion reactors. The applicability of an adiabatic assumption is explored and work is done experimentally to clarify the plasma compression process, which may be more generally polytropic. The device is capable of a much larger parameter space than previous machine iterations, allowing flexibility in the initial conditions of the compression process to preserve stability. This work is supported by DoE FES and NNSA.

  19. Ultra-High Density Single Nanometer-Scale Anodic Alumina Nanofibers Fabricated by Pyrophosphoric Acid Anodizing

    Science.gov (United States)

    Kikuchi, Tatsuya; Nishinaga, Osamu; Nakajima, Daiki; Kawashima, Jun; Natsui, Shungo; Sakaguchi, Norihito; Suzuki, Ryosuke O.

    2014-12-01

    Anodic oxide fabricated by anodizing has been widely used for nanostructural engineering, but the nanomorphology is limited to only two oxides: anodic barrier and porous oxides. Therefore, the discovery of an additional anodic oxide with a unique nanofeature would expand the applicability of anodizing. Here we demonstrate the fabrication of a third-generation anodic oxide, specifically, anodic alumina nanofibers, by anodizing in a new electrolyte, pyrophosphoric acid. Ultra-high density single nanometer-scale anodic alumina nanofibers (1010 nanofibers/cm2) consisting of an amorphous, pure aluminum oxide were successfully fabricated via pyrophosphoric acid anodizing. The nanomorphologies of the anodic nanofibers can be controlled by the electrochemical conditions. Anodic tungsten oxide nanofibers can also be fabricated by pyrophosphoric acid anodizing. The aluminum surface covered by the anodic alumina nanofibers exhibited ultra-fast superhydrophilic behavior, with a contact angle of less than 1°, within 1 second. Such ultra-narrow nanofibers can be used for various nanoapplications including catalysts, wettability control, and electronic devices.

  20. Nonlinear conductive properties and scaling behavior of conductive particle filled high-density polyethylene composites

    Institute of Scientific and Technical Information of China (English)

    ZHENG Qiang; SHEN Lie; LI Wenchun; SONG Yihu; YI Xiaosu

    2005-01-01

    The blends prepared by incorporation of carbon black (CB) or graphite powder (GP) inHto high-density polyethylene (HDPE) matrix have been novel and extensively applied polymeric positive temperature coefficient (PTC) composites. A phenomenological model was proposed on the basis of the GEM equation and the dilution effect of filler volume fraction due to the thermal volume expansion of the polymer matrix. Accordingly, the contribution of the thermal expansion of the matrix to the jump-like PTC transition of the composites was quantitatively estimated and a mechanical explanation was given. It was proved that the contribution of the volume expansion to PTC effect decreased for HDPE/CB composites crosslinked through electron-beam irradiation. Furthermore, the influences of the filler content, temperature and crosslinking on the self-heating behavior as well as the nonlinear conduction characteristics at electrical-thermal equilibrium state were examined. Based on the electric-field and initial resistivity dependence of the self-heating temperature and resistance dependence of the critical field, the mechanisms of the self-heating of the polymeric PTC materials were evaluated. The intrinsic relations between macroscopic electrical properties and microscopic percolation network at electrical-thermal equilibrium state were discussed according to the scaling relationship between the self-heating critical parameter and the conductivity of materials.

  1. The Density Matrix Renormalization Group Method and Large-Scale Nuclear Shell-Model Calculations

    CERN Document Server

    Dimitrova, S S; Pittel, S; Stoitsov, M V

    2002-01-01

    The particle-hole Density Matrix Renormalization Group (p-h DMRG) method is discussed as a possible new approach to large-scale nuclear shell-model calculations. Following a general description of the method, we apply it to a class of problems involving many identical nucleons constrained to move in a single large j-shell and to interact via a pairing plus quadrupole interaction. A single-particle term that splits the shell into degenerate doublets is included so as to accommodate the physics of a Fermi surface in the problem. We apply the p-h DMRG method to this test problem for two $j$ values, one for which the shell model can be solved exactly and one for which the size of the hamiltonian is much too large for exact treatment. In the former case, the method is able to reproduce the exact results for the ground state energy, the energies of low-lying excited states, and other observables with extreme precision. In the latter case, the results exhibit rapid exponential convergence, suggesting the great promi...

  2. Probability Density Function Characterization for Aggregated Large-Scale Wind Power Based on Weibull Mixtures

    Directory of Open Access Journals (Sweden)

    Emilio Gómez-Lázaro

    2016-02-01

    Full Text Available The Weibull probability distribution has been widely applied to characterize wind speeds for wind energy resources. Wind power generation modeling is different, however, due in particular to power curve limitations, wind turbine control methods, and transmission system operation requirements. These differences are even greater for aggregated wind power generation in power systems with high wind penetration. Consequently, models based on one-Weibull component can provide poor characterizations for aggregated wind power generation. With this aim, the present paper focuses on discussing Weibull mixtures to characterize the probability density function (PDF for aggregated wind power generation. PDFs of wind power data are firstly classified attending to hourly and seasonal patterns. The selection of the number of components in the mixture is analyzed through two well-known different criteria: the Akaike information criterion (AIC and the Bayesian information criterion (BIC. Finally, the optimal number of Weibull components for maximum likelihood is explored for the defined patterns, including the estimated weight, scale, and shape parameters. Results show that multi-Weibull models are more suitable to characterize aggregated wind power data due to the impact of distributed generation, variety of wind speed values and wind power curtailment.

  3. Activation volume of selected liquid crystals in the density scaling regime

    Science.gov (United States)

    Grzybowski, A.; Urban, S.; Mroz, S.; Paluch, M.

    2017-01-01

    In this paper, we demonstrate and thoroughly analyze the activation volumetric properties of selected liquid crystals in the nematic and crystalline E phases in comparison with those reported for glass-forming liquids. In the analysis, we have employed and evaluated two entropic models (based on either total or configurational entropies) to describe the longitudinal relaxation times of the liquid crystals in the density scaling regime. In this study, we have also exploited two equations of state: volumetric and activation volumetric ones. As a result, we have established that the activation volumetric properties of the selected liquid crystals are quite opposite to such typical properties of glass-forming materials, i.e., the activation volume decreases and the isothermal bulk modulus increases when a liquid crystal is isothermally compressed. Using the model based on the configurational entropy, we suggest that the increasing pressure dependences of the activation volume in isothermal conditions and the negative curvature of the pressure dependences of isothermal longitudinal relaxation times can be related to the formation of antiparallel doublets in the examined liquid crystals. A similar pressure effect on relaxation dynamics may be also observed for other material groups in case of systems, the molecules of which form some supramolecular structures. PMID:28181530

  4. Field and temperature scaling of the critical current density in commercial REBCO coated conductors

    CERN Document Server

    Senatore, Carmine; Bonura, Marco; Kulich, Miloslav; Mondonico, Giorgio

    2016-01-01

    Scaling relations describing the electromagnetic behaviour of coated conductors (CCs) greatly simplify the design of REBCO-based devices. The performance of REBCO CCs is strongly influenced by fabrication route, conductor architecture and materials, and these parameters vary from one manufacturer to the others. In the present work we have examined the critical surface for the current density, Jc(T,B,θ ), of coated conductors from six different manufacturers: American Superconductor Co. (US), Bruker HTS GmbH (Germany), Fujikura Ltd. (Japan), SuNAM Co. Ltd. (Korea), SuperOx ZAO (Russia) and SuperPower Inc. (US). Electrical transport and magnetic measurements were performed at temperatures between 4.2 K and 77 K and in magnetic field up to 19 T. Experiments were conducted at three different orientations of the field with respect to the crystallographic c-axis of the REBCO layer, θ = 0deg , 45deg and 90deg , in order to probe the angular anisotropy of Jc. In spite of the large variability of CCs performance, ...

  5. Control of high velocity lithosphere roots on crustal scale density variations seen in Gondwana reconstructions

    Science.gov (United States)

    Braitenberg, C. F.; Mariani, P.

    2015-12-01

    The GOCE gravity field is globally homogeneous at the resolution of about 80km or better allowing for the first time to identify tectonic structures at continental scale. The large scale structures are presumably controlled by the rheology of the underlying crust down to the base of the lithosphere. Seismic tomography identifies the presence of the deep lithosphere roots by increased velocity. The joint analysis of the tomography results and the GOCE gravity reveals that at global scale the two data have some common patterns. The correlations are enhanced by applying geodynamic plate reconstructions to the GOCE gravity field and to the tomography models which places today's observed fields at the Gondwana pre-breakup position. There are several examples for which it is found that the deep lithospheric roots, as those found below cratons, control the position of the positive gravity values outboard of the deep roots. This could be explained by the deep lithospheric roots focusing asthenospheric upwelling outboard of the root protecting the overlying craton from magmatic intrusions. Over several of the deep roots the gravity is systematically negative, which could be due to a compositional effect, with deep roots of increased velocity having reduced density. The study is carried out globally, with focus on the African and South American continents. The background for the study can be found in the following publications where the techniques which have been used are described: Braitenberg, C., Mariani, P. and De Min, A. (2013). The European Alps and nearby orogenic belts sensed by GOCE, Boll. Bollettino di Geofisica Teorica ed Applicata, 54(4), 321-334. doi:10.4430/bgta0105 Braitenberg, C. and Mariani, P. (2015). Geological implications from complete Gondwana GOCE-products reconstructions and link to lithospheric roots. Proceedings of 5th International GOCE User Workshop, 25 - 28 November 2014. Braitenberg, C. (2015). Exploration of tectonic structures with GOCE in

  6. Constructing multi-scale gravitational energy spectra from molecular cloud surface density PDF -- Interplay between turbulence and gravity

    CERN Document Server

    Li, Guang-Xing

    2016-01-01

    Gravity is believed to be important on multiple physical scales in molecular clouds. However, quantitative constraints on gravity are still lacking. We derive an analytical formula which provides estimates on multi-scale gravitational energy distribution using the observed surface density PDF. Our analytical formalism also enables one to convert the observed column density PDF into an estimated volume density PDF, and to obtain average radial profile $\\rho(r)$. For a region with $N_{\\rm col} \\sim N^{-\\gamma_{\\rm N}}$, the gravitational energy spectra is $E_{\\rm p}(k)\\sim k^{-4(1 - 1/\\gamma_{\\rm N})}$. We apply the formula to observations of molecular clouds, and find that a scaling index of $-2$ of the surface density PDF implies that $\\rho \\sim r^{-2}$ and $E_{\\rm p}(k) \\sim k^{-2}$. This indicates that gravity can act effectively against turbulence over a multitude of physical scales. This is the critical scaling index which divides molecular clouds into two categories: clouds like Orion and Ophiuchus have ...

  7. Scaling of stomatal size and density optimizes allocation of leaf epidermal space for gas exchange in angiosperms

    Science.gov (United States)

    de Boer, Hugo Jan; Price, Charles A.; Wagner-Cremer, Friederike; Dekker, Stefan C.; Franks, Peter J.; Veneklaas, Erik J.

    2015-04-01

    Stomata on plant leaves are key traits in the regulation of terrestrial fluxes of water and carbon. The basic morphology of stomata consists of a diffusion pore and two guard cells that regulate the exchange of CO2 and water vapour between the leaf interior and the atmosphere. This morphology is common to nearly all land plants, yet stomatal size (defined as the area of the guard cell pair) and stomatal density (the number of stomata per unit area) range over three orders of magnitude across species. Evolution of stomatal sizes and densities is driven by selection pressure on the anatomical maximum stomatal conductance (gsmax), which determines the operational range of leaf gas exchange. Despite the importance of stomata traits for regulating leaf gas exchange, a quantitative understanding of the relation between adaptation of gsmax and the underlying co-evolution of stomatal sizes and densities is still lacking. Here we develop a theoretical framework for a scaling relationship between stomatal sizes and densities within the constraints set by the allocation of epidermal space and stomatal gas exchange. Our theory predicts an optimal scaling relationship that maximizes gsmax and minimizes epidermal space allocation to stomata. We test whether stomatal sizes and densities reflect this optimal scaling with a global compilation of stomatal trait data on 923 species reflecting most major clades. Our results show optimal scaling between stomatal sizes and densities across all species in the compiled data set. Our results also show optimal stomatal scaling across angiosperm species, but not across gymnosperm and fern species. We propose that the evolutionary flexibility of angiosperms to adjust stomatal sizes underlies their optimal allocation of leaf epidermal space to gas exchange.

  8. The scaling functions of the free energy density and its derivatives for the 3d O(4) model

    CERN Document Server

    Engels, Juergen

    2011-01-01

    We derive direct representations of the scaling functions of the 3d O(4) model which are relevant for comparisons to other models, in particular QCD. This is done in terms of expansions in the scaling variable z= t/h^{1/Delta}. The expansions around z=0 and the corresponding asymptotic ones for z --> +- infinity overlap such that no interpolation is needed. The expansion coefficients are determined numerically from the data of a previous high statistics simulation of the O(4) model on a three-dimensional lattice of linear extension L=120. From the scaling function of the magnetization we calculate the leading asymptotic coefficients of the scaling function of the free energy density. As a result we obtain the universal amplitude ratio A^+/A^-=1.84(4) for the specific heat. Comparing the scaling function of the energy density to the data we find the non-singular part of the energy density epsilon_{ns}(T) with high precision and at the same time excellent scaling properties.

  9. Equation of state in the generalized density scaling regime studied from ambient to ultra-high pressure conditions

    Science.gov (United States)

    Grzybowski, A.; Koperwas, K.; Paluch, M.

    2014-01-01

    In this paper, based on the effective intermolecular potential with well separated density and configuration contributions and the definition of the isothermal bulk modulus, we derive two similar equations of state dedicated to describe volumetric data of supercooled liquids studied in the extremely wide pressure range related to the density range, which is extremely wide in comparison with the experimental range reached so far in pressure-volume-temperature measurements of glass-forming liquids. Both the equations comply with the generalized density scaling law of molecular dynamics versus h(ρ)/T at different densities ρ and temperatures T, where the scaling exponent can be in general only a density function γ(ρ) = d ln h/d ln ρ as recently argued by the theory of isomorphs. We successfully verify these equations of state by using data obtained from molecular dynamics simulations of the Kob-Andersen binary Lennard-Jones liquid. As a very important result, we find that the one-parameter density function h(ρ) analytically formulated in the case of this prototypical model of supercooled liquid, which implies the one-parameter density function γ(ρ), is able to scale the structural relaxation times with the value of this function parameter determined by fitting the volumetric simulation data to the equations of state. We also show that these equations of state properly describe the pressure dependences of the isothermal bulk modulus and the configurational isothermal bulk modulus in the extremely wide pressure range investigated by the computer simulations. Moreover, we discuss the possible forms of the density functions h(ρ) and γ(ρ) for real glass formers, which are suggested to be different from those valid for the model of supercooled liquid based on the Lennard-Jones intermolecular potential.

  10. Climate and Edaphic Controls on Humid Tropical Forest Tree Height

    Science.gov (United States)

    Yang, Y.; Saatchi, S. S.; Xu, L.

    2014-12-01

    Uncertainty in the magnitude and spatial variations of forest carbon density in tropical regions is due to under sampling of forest structure from inventory plots and the lack of regional allometry to estimate the carbon density from structure. Here we quantify the variation of tropical forest structure by using more than 2.5 million measurements of canopy height from systematic sampling of Geoscience Laser Altimeter System (GLAS) satellite observations between 2004 to 2008 and examine the climate and edaphic variables influencing the variations. We used top canopy height of GLAS footprints (~ 0.25 ha) to grid the statistical mean and 90 percentile of samples at 0.5 degrees to capture the regional variability of large trees in tropics. GLAS heights were also aggregated based on a stratification of tropical regions using soil, elevation, and forest types. Both approaches provided consistent patterns of statistically dominant large trees and the least heterogeneity, both as strong drivers of distribution of high biomass forests. Statistical models accounting for spatial autocorrelation suggest that climate, soil and spatial features together can explain more than 60% of the variations in observed tree height information, while climate-only variables explains about one third of the first-order changes in tree height. Soil basics, including physical compositions such as clay and sand contents, chemical properties such as PH values and cation-exchange capacity, as well as biological variables such as organic matters, all present independent but statistically significant relationships to tree height variations. The results confirm other landscape and regional studies that soil fertility, geology and climate may jointly control a majority of the regional variations of forest structure in pan-tropics and influencing both biomass stocks and dynamics. Consequently, other factors such as biotic and disturbance regimes, not included in this study, may have less influence on

  11. Landscape-scale distribution and density of raptor populations wintering in anthropogenic-dominated desert landscapes

    Science.gov (United States)

    Duerr, Adam E.; Miller, Tricia A.; Cornell Duerr, Kerri L; Lanzone, Michael J; Fesnock, Amy; Katzner, Todd Eli

    2015-01-01

    Anthropogenic development has great potential to affect fragile desert environments. Large-scale development of renewable energy infrastructure is planned for many desert ecosystems. Development plans should account for anthropogenic effects to distributions and abundance of rare or sensitive wildlife; however, baseline data on abundance and distribution of such wildlife are often lacking. We surveyed for predatory birds in the Sonoran and Mojave Deserts of southern California, USA, in an area designated for protection under the “Desert Renewable Energy Conservation Plan”, to determine how these birds are distributed across the landscape and how this distribution is affected by existing development. We developed species-specific models of resight probability to adjust estimates of abundance and density of each individual common species. Second, we developed combined-species models of resight probability for common and rare species so that we could make use of sparse data on the latter. We determined that many common species, such as red-tailed hawks, loggerhead shrikes, and especially common ravens, are associated with human development and likely subsidized by human activity. Species-specific and combined-species models of resight probability performed similarly, although the former model type provided higher quality information. Comparing abundance estimates with past surveys in the Mojave Desert suggests numbers of predatory birds associated with human development have increased while other sensitive species not associated with development have decreased. This approach gave us information beyond what we would have collected by focusing either on common or rare species, thus it provides a low-cost framework for others conducting surveys in similar desert environments outside of California.

  12. Reactor-scale cultivation of the hyperthermophilic methanarchaeon Methanococcus jannaschii to high cell densities.

    Science.gov (United States)

    Mukhopadhyay, B; Johnson, E F; Wolfe, R S

    1999-11-01

    For the hyperthermophilic and barophilic methanarchaeon Methanococcus jannaschii, we have developed a medium and protocols for reactor-scale cultivation that improved the final cell yield per liter from approximately 0.5 to approximately 7.5 g of packed wet cells ( approximately 1.8 g dry cell mass) under autotrophic growth conditions and to approximately 8.5 g of packed wet cells ( approximately 2 g dry cell mass) with yeast extract (2 g liter(-1)) and tryptone (2 g liter(-1)) as medium supplements. For growth in a sealed bottle it was necessary to add Se to the medium, and a level of 2 microM for added Se gave the highest final cell yield. In a reactor M. jannaschii grew without added Se in the medium; it is plausible that the cells received Se as a contaminant from the reactor vessel and the H(2)S supply. But, for the optimal performance of a reactor culture, an addition of Se to a final concentration of 50 to 100 microM was needed. Also, cell growth in a reactor culture was inhibited at much higher Se concentrations. These observations and the data from previous work with methanogen cell extracts (B. C. McBride and R. S. Wolfe, Biochemistry 10:4312-4317, 1971) suggested that from a continuously sparged reactor culture Se was lost in the exhaust gas as volatile selenides, and this loss raised the apparent required level of and tolerance for Se. In spite of having a proteinaceous cell wall, M. jannaschii withstood an impeller tip speed of 235.5 cms(-1), which was optimal for achieving high cell density and also was the higher limit for the tolerated shear rate. The organism secreted one or more acidic compounds, which lowered pH in cultures without pH control; this secretion continued even after cessation of growth.

  13. Effective spatial scales for evaluating environmental determinants of population density in Yakushima macaques

    OpenAIRE

    Agetsuma, Naoki; Koda, Ryosuke; Tsujino, Riyou; Agetsuma-Yanagihara, Yoshimi

    2015-01-01

    Population densities of wildlife species tend to be correlated with resource productivity of habitats. However, wildlife density has been greatly modified by increasing human influences. For effective conservation, we must first identify the significant factors that affect wildlife density, and then determine the extent of the areas in which the factors should be managed. Here, we propose a protocol that accomplishes these two tasks. The main threats to wildlife are thought to be habitat alte...

  14. Preliminary scaling laws for plasma current, ion kinetic temperature, and plasma number density in the NASA Lewis bumpy torus plasma

    Science.gov (United States)

    Roth, J. R.

    1976-01-01

    Parametric variation of independent variables which may affect the characteristics of bumpy torus plasma have identified those which have a significant effect on the plasma current, ion kinetic temperature, and plasma number density, and those which do not. Empirical power law correlations of the plasma current, and the ion kinetic temperature and number density were obtained as functions of potential applied to the midplane electrode rings, the background neutral gas pressure, and the magnetic field strength. Additional parameters studied included the type of gas, the polarity of the midplane electrode rings, the mode of plasma operation, and the method of measuring the plasma number density. No significant departures from the scaling laws appear to occur at the highest ion kinetic temperatures or number densities obtained to date.

  15. Effects of water salinity on the correlation scale of Root density and Evapotranspiration fluxes

    Science.gov (United States)

    Ajeel, Ali; Saeed, Ali; Dragonetti, Giovanna; Comegna, Alessandro; Lamaddalena, Nicola; Coppola, Antonio

    2015-04-01

    Spatial pattern and the correlation of different soil and plant parameters were examined in a green bean field experiment carried out at the Mediterranean Agronomic Institute of Bari, Italy. The experiment aimed to evaluate the role of local processes of salt accumulation and transport which mainly influences the evapotranspiration (and thus the root uptake) processes under different water salinity levels. The experiment consisted of three transects of 30m length and 4.2 m width, irrigated with three different salinity levels (1dSm-1, 3dSm-1, 6dSm-1). Soil measurements (electrical conductivity and soil water content) were monitored along transects in 24 sites, 1 m apart by using TDR probes and Diviner 2000. Water storage measured by TDR and Diviner sensor were coupled for calculating directly the evapotranspiration fluxes along the whole soil profile under the different salinity levels imposed during the experiment. In the same sites, crop monitoring involved measurements of Leaf Area Index (LAI), Osmotic Potential (OP), Leaf Water Potential (LWP), and Root length Density (RlD). Soil and plant properties were analyzed by classical statistics, geostatistics methods and spectral analysis. Results indicated moderate to large spatial variability across the field for soil and plant parameters under all salinity treatments. Furthermore, cross-semivariograms exhibited a strong positive spatial interdependence between electrical conductivity of soil solution ECw with ET and RlD in transect treated with 3dSm-1 as well as with LAI in transect treated with 6dSm-1 at all 24 monitoring sites. Spectral analysis enabled to identify the observation window to sample the soil salinity information responsible for a given plant response (ET, OP, RlD). It is also allowed a clear identification of the spatial scale at which the soil water salinity level and distribution and the crop response in terms of actual evapotranspiration ET, RlD and OP, are actually correlated. Additionally

  16. Molecular Density Functional Theory of Water describing Hydrophobicity at Short and Long Length Scales

    CERN Document Server

    Jeanmairet, Guillaume; Borgis, Daniel

    2013-01-01

    We present an extension of our recently introduced molecular density functional theory of water [G. Jeanmairet et al., J. Phys. Chem. Lett. 4, 619, 2013] to the solvation of hydrophobic solutes of various sizes, going from angstroms to nanometers. The theory is based on the quadratic expansion of the excess free energy in terms of two classical density fields, the particle density and the multipolar polarization density. Its implementation requires as input a molecular model of water and three measurable bulk properties, namely the structure factor and the k-dependent longitudinal and transverse dielectric susceptibilities. The fine three-dimensional water structure around small hydrophobic molecules is found to be well reproduced. In contrast the computed solvation free-energies appear overestimated and do not exhibit the correct qualitative behavior when the hydrophobic solute is grown in size. These shortcomings are corrected, in the spirit of the Lum-Chandler-Weeks theory, by complementing the functional ...

  17. Statistical Analysis of the Spectral Density Estimate Obtained via Coifman Scaling Function

    OpenAIRE

    2007-01-01

    Spectral density built as Fourier transform of covariance sequence of stationary random process is determining the process characteristics and makes for analysis of it’s structure. Thus, one of the main problems in time series analysis is constructing consistent estimates of spectral density via successive, taken after equal periods of time observations of stationary random process. This article is devoted to investigation of problems dealing with application of wavelet anal...

  18. Surface density of dark matter haloes on galactic and cluster scales

    Science.gov (United States)

    Del Popolo, A.; Cardone, V. F.; Belvedere, G.

    2013-02-01

    In this paper, we analysed the correlation between the central surface density and the halo core radius of galaxies, and cluster of galaxies dark matter (DM) haloes, in the framework of the secondary infall model. We used Del Popolo secondary infall model taking into account ordered and random angular momentum, dynamical friction and DM adiabatic contraction to calculate the density profile of haloes, and then these profiles are used to determine the surface density of DM haloes. The main result is that r* (the halo characteristic radius) is not a universal quantity as claimed by Donato et al. and Gentile et al. On the contrary, we find a correlation with the halo mass M200 in agreement with Cardone & Tortora, Boyarsky et al. and Napolitano, Romanowsky & Tortora, but with a significantly smaller scatter, namely 0.16 ± 0.05. We also consider the baryon column density finding this latter being indeed a constant for low-mass systems, such as dwarfs, but correlating with mass with a slope of α = 0.18 ± 0.05. In the case of the surface density of DM for a system composed only of DM, as in dissipationless simulations, we get α = 0.20 ± 0.05. These results leave little room for the recently claimed universality of (dark and stellar) column density.

  19. Finite-size scaling of the magnetization probability density for the critical Ising model in slab geometry

    Science.gov (United States)

    Lopes Cardozo, David; Holdsworth, Peter C. W.

    2016-04-01

    The magnetization probability density in d  =  2 and 3 dimensional Ising models in slab geometry of volume L\\paralleld-1× {{L}\\bot} is computed through Monte-Carlo simulation at the critical temperature and zero magnetic field. The finite-size scaling of this distribution and its dependence on the system aspect-ratio ρ =\\frac{{{L}\\bot}}{{{L}\\parallel}} and boundary conditions are discussed. In the limiting case ρ \\to 0 of a macroscopically large slab ({{L}\\parallel}\\gg {{L}\\bot} ) the distribution is found to scale as a Gaussian function for all tested system sizes and boundary conditions.

  20. Analysis of Self Similar Scaling in Kinetic and Magnetic Energy Density as a Function of Distance From Sun

    Science.gov (United States)

    Banerjee, A.; Coplan, M. A.

    2009-12-01

    We analyze solar wind and interplanetary magnetic field data to study scaling properties of kinetic and magnetic energy density as a function of solar cycle and distance from the sun. In his original theory on turbulence, Kolmogorov predicted that in the inertial range the fluctuations in velocity differences should be self-similar. Analysis of solar wind data showed this not to be the case. On the other hand B. Hnat et.al.(Geophys. Res. Lett., 29 (10), 1446, 2002) and J.J Podesta (J. Geophys. Res., 111, A09105, 2006) showed that fluctuations in kinetic and magnetic energy density are approximately self-similar. We extend this analysis using data from the SWE and MFI experiments on the WIND spacecraft (at 1AU) during solar minimum (2006) and solar maximum (2001) and VHM/FGM experiment on the Ulysses spacecraft (1AU to 5AU). We calculate the cumulative distribution function (CDF) of the time delayed differences in kinetic and magnetic energy density and present a method through which the scaling exponent can be reliably calculated from the CDFs, instead of using structure functions which are very sensitive to large fluctuations. We compare the scaling exponents derived from the CDFs to the ones calculated from structure functions and study the rescaling properties of CDFs.

  1. Development of large Area Covering Height Model

    Science.gov (United States)

    Jacobsen, K.

    2014-04-01

    Height information is a basic part of topographic mapping. Only in special areas frequent update of height models is required, usually the update cycle is quite lower as for horizontal map information. Some height models are available free of charge in the internet; for commercial height models a fee has to be paid. Mostly digital surface models (DSM) with the height of the visible surface are given and not the bare ground height, as required for standard mapping. Nevertheless by filtering of DSM, digital terrain models (DTM) with the height of the bare ground can be generated with the exception of dense forest areas where no height of the bare ground is available. These height models may be better as the DTM of some survey administrations. In addition several DTM from national survey administrations are classified, so as alternative the commercial or free of charge available information from internet can be used. The widely used SRTM DSM is available also as ACE-2 GDEM corrected by altimeter data for systematic height errors caused by vegetation and orientation errors. But the ACE-2 GDEM did not respect neighbourhood information. With the worldwide covering TanDEM-X height model, distributed starting 2014 by Airbus Defence and Space (former ASTRIUM) as WorldDEM, higher level of details and accuracy is reached as with other large area covering height models. At first the raw-version of WorldDEM will be available, followed by an edited version and finally as WorldDEM-DTM a height model of the bare ground. With 12 m spacing and a relative standard deviation of 1.2 m within an area of 1° x 1° an accuracy and resolution level is reached, satisfying also for larger map scales. For limited areas with the HDEM also a height model with 6 m spacing and a relative vertical accuracy of 0.5 m can be generated on demand. By bathymetric LiDAR and stereo images also the height of the sea floor can be determined if the water has satisfying transparency. Another method of getting

  2. Plant diversity increases with the strength of negative density dependence at the global scale

    Science.gov (United States)

    Joseph A. LaManna; Scott A. Mangan; Alfonso Alonso; Norman A. Bourg; Warren Y. Brockelman; Sarayudh Bunyavejchewin; Li-Wan Chang; Jyh-Min Chiang; George B. Chuyong; Keith Clay; Richard Condit; Susan Cordell; Stuart J. Davies; Tucker J. Furniss; Christian P. Giardina; I. A. U. Nimal Gunatilleke; C. V. Savitri Gunatilleke; Fangliang He; Robert W. Howe; Stephen P. Hubbell; Chang-Fu Hsieh; Faith M. Inman-Narahari; David Janík; Daniel J. Johnson; David Kenfack; Lisa Korte; Kamil Král; Andrew J. Larson; James A. Lutz; Sean M. McMahon; William J. McShea; Hervé R. Memiaghe; Anuttara Nathalang; Vojtech Novotny; Perry S. Ong; David A. Orwig; Rebecca Ostertag; Geoffrey G. Parker; Richard P. Phillips; Lawren Sack; I-Fang Sun; J. Sebastián Tello; Duncan W. Thomas; Benjamin L. Turner; Dilys M. Vela Díaz; Tomáš Vrška; George D. Weiblen; Amy Wolf; Sandra Yap; Jonathan A. Myers

    2017-01-01

    Theory predicts that higher biodiversity in the tropics is maintained by specialized interactions among plants and their natural enemies that result in conspecific negative density dependence (CNDD). By using more than 3000 species and nearly 2.4 million trees across 24 forest plots worldwide, we show that global patterns in tree species diversity reflect not only...

  3. Efficient synthesis of large-scale thinned arrays using a density-taper initialised genetic algorithm

    CSIR Research Space (South Africa)

    Du Plessis, WP

    2011-09-01

    Full Text Available The use of the density-taper approach to initialise a genetic algorithm is shown to give excellent results in the synthesis of thinned arrays. This approach is shown to give better SLL values more consistently than using random values and difference...

  4. Scaled Quantum Mechanical scale factors for vibrational calculations using alternate polarized and augmented basis sets with the B3LYP density functional calculation model.

    Science.gov (United States)

    Legler, C R; Brown, N R; Dunbar, R A; Harness, M D; Nguyen, K; Oyewole, O; Collier, W B

    2015-06-15

    The Scaled Quantum Mechanical (SQM) method of scaling calculated force constants to predict theoretically calculated vibrational frequencies is expanded to include a broad array of polarized and augmented basis sets based on the split valence 6-31G and 6-311G basis sets with the B3LYP density functional. Pulay's original choice of a single polarized 6-31G(d) basis coupled with a B3LYP functional remains the most computationally economical choice for scaled frequency calculations. But it can be improved upon with additional polarization functions and added diffuse functions for complex molecular systems. The new scale factors for the B3LYP density functional and the 6-31G, 6-31G(d), 6-31G(d,p), 6-31G+(d,p), 6-31G++(d,p), 6-311G, 6-311G(d), 6-311G(d,p), 6-311G+(d,p), 6-311G++(d,p), 6-311G(2d,p), 6-311G++(2d,p), 6-311G++(df,p) basis sets are shown. The double d polarized models did not perform as well and the source of the decreased accuracy was investigated. An alternate system of generating internal coordinates that uses the out-of plane wagging coordinate whenever it is possible; makes vibrational assignments via potential energy distributions more meaningful. Automated software to produce SQM scaled vibrational calculations from different molecular orbital packages is presented.

  5. Universal properties of 3d O(4) symmetric models: The scaling function of the free energy density and its derivatives

    CERN Document Server

    Karsch, Frithjof

    2011-01-01

    We present direct representations of the scaling functions of the 3d O(4) model which are relevant for comparisons to other models, in particular QCD. This is done in terms of expansions in the scaling variable z=t/h^{1/\\beta\\delta}. The expansions around z=0 and the corresponding asymptotic ones for z --> +/- infty, overlap such that no interpolation is needed. We explicitly present the expansion coefficients which have been determined numerically from data of a previous high statistics simulation of the O(4) model on a three-dimensional lattice of linear extension L=120. This allows to derive smooth representations of the first three derivatives of the scaling function of the free energy density, which determine universal properties of up to sixth order cumulants of net charge fluctuations in QCD.

  6. Large-scale atomistic simulations of nanostructured materials based on divide-and-conquer density functional theory

    Directory of Open Access Journals (Sweden)

    Vashishta P.

    2011-05-01

    Full Text Available A linear-scaling algorithm based on a divide-and-conquer (DC scheme is designed to perform large-scale molecular-dynamics simulations, in which interatomic forces are computed quantum mechanically in the framework of the density functional theory (DFT. This scheme is applied to the thermite reaction at an Al/Fe2O3 interface. It is found that mass diffusion and reaction rate at the interface are enhanced by a concerted metal-oxygen flip mechanism. Preliminary simulations are carried out for an aluminum particle in water based on the conventional DFT, as a target system for large-scale DC-DFT simulations. A pair of Lewis acid and base sites on the aluminum surface preferentially catalyzes hydrogen production in a low activation-barrier mechanism found in the simulations

  7. Radiation from particles moving in small-scale magnetic fields created in solid-density laser-plasma laboratory experiments

    Energy Technology Data Exchange (ETDEWEB)

    Keenan, Brett D., E-mail: bdkeenan@ku.edu; Medvedev, Mikhail V. [Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045 (United States)

    2015-11-15

    Plasmas created by high-intensity lasers are often subject to the formation of kinetic-streaming instabilities, such as the Weibel instability, which lead to the spontaneous generation of high-amplitude, tangled magnetic fields. These fields typically exist on small spatial scales, i.e., “sub-Larmor scales.” Radiation from charged particles moving through small-scale electromagnetic (EM) turbulence has spectral characteristics distinct from both synchrotron and cyclotron radiation, and it carries valuable information on the statistical properties of the EM field structure and evolution. Consequently, this radiation from laser-produced plasmas may offer insight into the underlying electromagnetic turbulence. Here, we investigate the prospects for, and demonstrate the feasibility of, such direct radiative diagnostics for mildly relativistic, solid-density laser plasmas produced in lab experiments.

  8. Experimental study of cake formation on heat treated and membrane coated needle felts in a pilot scale pulse jet bag filter using optical in-situ cake height measurement.

    Science.gov (United States)

    Saleem, Mahmood; Khan, Rafi Ullah; Tahir, M Suleman; Krammer, Gernot

    2011-12-25

    Pulse-jet bag filters are frequently employed for particle removal from off gases. Separated solids form a layer on the permeable filter media called filter cake. The cake is responsible for increasing pressure drop. Therefore, the cake has to be detached at a predefined upper pressure drop limit or at predefined time intervals. Thus the process is intrinsically semi-continuous. The cake formation and cake detachment are interdependent and may influence the performance of the filter. Therefore, understanding formation and detachment of filter cake is important. In this regard, the filter media is the key component in the system. Needle felts are the most commonly used media in bag filters. Cake formation studies with heat treated and membrane coated needle felts in pilot scale pulse jet bag filter were carried out. The data is processed according to the procedures that were published already [Powder Technology, Volume 173, Issue 2, 19 April 2007, Pages 93-106]. Pressure drop evolution, cake height distribution evolution, cake patches area distribution and their characterization using fractal analysis on different needle felts are presented here. It is observed that concavity of pressure drop curve for membrane coated needle felt is principally caused by presence of inhomogeneous cake area load whereas it is inherent for heat treated media. Presence of residual cake enhances the concavity of pressure drop at the start of filtration cycle. Patchy cleaning is observed only when jet pulse pressure is too low and unable to provide the necessary force to detach the cake. The border line is very sharp. Based on experiments with limestone dust and three types of needle felts, for the jet pulse pressure above 4 bar and filtration velocity below 50 mm/s, cake is detached completely except a thin residual layer (100-200 μm). Uniformity and smoothness of residual cake depends on the surface characteristics of the filter media. Cake height distribution of residual cake and

  9. Subspace accelerated inexact Newton method for large scale wave functions calculations in Density Functional Theory

    Energy Technology Data Exchange (ETDEWEB)

    Fattebert, J

    2008-07-29

    We describe an iterative algorithm to solve electronic structure problems in Density Functional Theory. The approach is presented as a Subspace Accelerated Inexact Newton (SAIN) solver for the non-linear Kohn-Sham equations. It is related to a class of iterative algorithms known as RMM-DIIS in the electronic structure community. The method is illustrated with examples of real applications using a finite difference discretization and multigrid preconditioning.

  10. Impact of the pedestal plasma density on dynamics of edge localized mode crashes and energy loss scaling

    Energy Technology Data Exchange (ETDEWEB)

    Xu, X. Q., E-mail: xxu@llnl.gov [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Ma, J. F. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Institute for Fusion Studies, University of Texas, Austin, Texas 78712 (United States); Li, G. Q. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China)

    2014-12-15

    The latest BOUT++ studies show an emerging understanding of dynamics of edge localized mode (ELM) crashes and the consistent collisionality scaling of ELM energy losses with the world multi-tokamak database. A series of BOUT++ simulations are conducted to investigate the scaling characteristics of the ELM energy losses vs collisionality via a density scan. Linear results demonstrate that as the pedestal collisionality decreases, the growth rate of the peeling-ballooning modes decreases for high n but increases for low n (1 < n < 5), therefore the width of the growth rate spectrum γ(n) becomes narrower and the peak growth shifts to lower n. Nonlinear BOUT++ simulations show a two-stage process of ELM crash evolution of (i) initial bursts of pressure blob and void creation and (ii) inward void propagation. The inward void propagation stirs the top of pedestal plasma and yields an increasing ELM size with decreasing collisionality after a series of micro-bursts. The pedestal plasma density plays a major role in determining the ELM energy loss through its effect on the edge bootstrap current and ion diamagnetic stabilization. The critical trend emerges as a transition (1) linearly from ballooning-dominated states at high collisionality to peeling-dominated states at low collisionality with decreasing density and (2) nonlinearly from turbulence spreading dynamics at high collisionality into avalanche-like dynamics at low collisionality.

  11. High critical current densities in industrial scale composites made from high homogeneity NB 46. 5 TI

    Energy Technology Data Exchange (ETDEWEB)

    Larbalestier, D.C.; Hemachalam, K.; Lee, P.; McDonald, W.K.; O' Larey, P.; Scanlan, R.; Starch, W.; Taylor, C.; Warnes, W.; West, A.W.; Zeitlin, B.

    1985-03-01

    Recent work in our group on the fabricationmicrostructure-superconducting properties of composites of Nb-Ti has produced much new information about the precipitate morphology and origins of high critical current density (J /SUB c/ ) in these materials./sup 1 -4/ Precipitation of Ti-rich phase is seen to commence as a grain boundary film 2 - 4 nm thick, the film then developing into approximately equiaxed particles of ..cap alpha..-Ti at the boundary triple points. The typical size of such precipitates is 50 - 100 nm. Controlled drawing of such a structure produces an array of locally ordered ribbon precipitates. These precipitates are typically 3 - 5 nm thick by 100 - 300 nm long (when observed in transverse section). Their length in longitudinal section appears to be several hundred nm, indicating great ductility in these small ..cap alpha..-Ti precipitates. The typical separation of the precipitates is 20 - 30 nm. Thus the dimensions of the precipitate array are quite comparable to that of the flux lattice since the fluxoid separation is 22 nm at 5 T and the fluxoid diameter of Nb 46.5 wt% Ti is approximately 10 nm. The flux pinning behavior of these precipitate structures is expected to be complex: /SUP 2.4/ the defect density is very high, the precipitate morphology has a very high aspect ratio and the extreme thinness of the precipitates must permit some superconductivity to be induced in them by the proximity effect./sup 5/

  12. On Wuthering Heights

    Institute of Scientific and Technical Information of China (English)

    马春玲

    2001-01-01

    本文剖析了小说主人公的悲惨命运及时代特征%Through the story of Wuthering Heights,the article analyzes the tragic fate of Heathcliff and the characteristic of the 19th century England.

  13. Narrators in Wuthering Heights

    Institute of Scientific and Technical Information of China (English)

    刘俊红

    2009-01-01

    Wuthering Heights is Emily Bront e's only novel. The narrative is non-linear, involving several flashbacks an dtwo primary narrators. Emily Bronte has adopted the device of introducing two narrators--Mr. Lockwood and Ellen "Nel-ly" Dean so as to achieve certain purpose.

  14. A regional-scale, high resolution dynamical malaria model that accounts for population density, climate and surface hydrology.

    Science.gov (United States)

    Tompkins, Adrian M; Ermert, Volker

    2013-02-18

    The relative roles of climate variability and population related effects in malaria transmission could be better understood if regional-scale dynamical malaria models could account for these factors. A new dynamical community malaria model is introduced that accounts for the temperature and rainfall influences on the parasite and vector life cycles which are finely resolved in order to correctly represent the delay between the rains and the malaria season. The rainfall drives a simple but physically based representation of the surface hydrology. The model accounts for the population density in the calculation of daily biting rates. Model simulations of entomological inoculation rate and circumsporozoite protein rate compare well to data from field studies from a wide range of locations in West Africa that encompass both seasonal endemic and epidemic fringe areas. A focus on Bobo-Dioulasso shows the ability of the model to represent the differences in transmission rates between rural and peri-urban areas in addition to the seasonality of malaria. Fine spatial resolution regional integrations for Eastern Africa reproduce the malaria atlas project (MAP) spatial distribution of the parasite ratio, and integrations for West and Eastern Africa show that the model grossly reproduces the reduction in parasite ratio as a function of population density observed in a large number of field surveys, although it underestimates malaria prevalence at high densities probably due to the neglect of population migration. A new dynamical community malaria model is publicly available that accounts for climate and population density to simulate malaria transmission on a regional scale. The model structure facilitates future development to incorporate migration, immunity and interventions.

  15. Quantitative calcaneal ultrasound parameters and bone mineral density at final height in girls treated with depot gonadotrophin-releasing hormone agonist for central precocious puberty or idiopathic short stature.

    NARCIS (Netherlands)

    Kordelaar, S. van; Noordam, C.; Otten, B.J.; Bergh, J.P.W. van den

    2003-01-01

    To evaluate the effect of gonadotrophin-releasing hormone (GnRH) agonist treatment on bone quality at final height, we studied girls with central precocious puberty (CPP) and with idiopathic short stature (ISS). A total of 25 Caucasian girls were included: group A (n=14) with idiopathic CPP (mean ag

  16. Hydration of Clays at the Molecular Scale: The Promising Perspective of Classical Density Functional Theory

    CERN Document Server

    Jeanmairet, Guillaume; Levesque, Maximilien; Rotenberg, Benjamin; Borgis, Daniel

    2014-01-01

    We report here how the hydration of complex surfaces can be efficiently studied thanks to recent advances in classical molecular density functional theory. This is illustrated on the example of the pyrophylite clay. After presenting the most recent advances, we show that the strength of this implicit method is that (i) it is in quantitative or semi-quantitative agreement with reference all-atoms simulations (molecular dynamics here) for both the solvation structure and energetics, and that (ii) the computational cost is two to three orders of magnitude less than in explicit methods. The method remains imperfect, in that it locally overestimates the polarization of water close to hydrophylic sites of the clay. The high numerical efficiency of the method is illustrated and exploited to carry a systematic study of the electrostatic and van der Waals components of the surface-solvant interactions within the most popular force field for clays, CLAYFF. Hydration structure and energetics are found to weakly depend u...

  17. The tensor hypercontracted parametric reduced density matrix algorithm: coupled-cluster accuracy with O(r^4) scaling

    CERN Document Server

    Shenvi, Neil; Yang, Yang; Yang, Weitao; Schwerdtfeger, Christine; Mazziotti, David

    2013-01-01

    Tensor hypercontraction is a method that allows the representation of a high-rank tensor as a product of lower-rank tensors. In this paper, we show how tensor hypercontraction can be applied to both the electron repulsion integral (ERI) tensor and the two-particle excitation amplitudes used in the parametric reduced density matrix (pRDM) algorithm. Because only O(r) auxiliary functions are needed in both of these approximations, our overall algorithm can be shown to scale as O(r4), where r is the number of single-particle basis functions. We apply our algorithm to several small molecules, hydrogen chains, and alkanes to demonstrate its low formal scaling and practical utility. Provided we use enough auxiliary functions, we obtain accuracy similar to that of the traditional pRDM algorithm, somewhere between that of CCSD and CCSD(T).

  18. The tensor hypercontracted parametric reduced density matrix algorithm: coupled-cluster accuracy with O(r(4)) scaling.

    Science.gov (United States)

    Shenvi, Neil; van Aggelen, Helen; Yang, Yang; Yang, Weitao; Schwerdtfeger, Christine; Mazziotti, David

    2013-08-07

    Tensor hypercontraction is a method that allows the representation of a high-rank tensor as a product of lower-rank tensors. In this paper, we show how tensor hypercontraction can be applied to both the electron repulsion integral tensor and the two-particle excitation amplitudes used in the parametric 2-electron reduced density matrix (p2RDM) algorithm. Because only O(r) auxiliary functions are needed in both of these approximations, our overall algorithm can be shown to scale as O(r(4)), where r is the number of single-particle basis functions. We apply our algorithm to several small molecules, hydrogen chains, and alkanes to demonstrate its low formal scaling and practical utility. Provided we use enough auxiliary functions, we obtain accuracy similar to that of the standard p2RDM algorithm, somewhere between that of CCSD and CCSD(T).

  19. Reactor-Scale Cultivation of the Hyperthermophilic Methanarchaeon Methanococcus jannaschii to High Cell Densities

    OpenAIRE

    Mukhopadhyay, Biswarup; Johnson, Eric F.; Wolfe, Ralph S.

    1999-01-01

    For the hyperthermophilic and barophilic methanarchaeon Methanococcus jannaschii, we have developed a medium and protocols for reactor-scale cultivation that improved the final cell yield per liter from ∼0.5 to ∼7.5 g of packed wet cells (∼1.8 g dry cell mass) under autotrophic growth conditions and to ∼8.5 g of packed wet cells (∼2 g dry cell mass) with yeast extract (2 g liter−1) and tryptone (2 g liter−1) as medium supplements. For growth in a sealed bottle it was necessary to add Se to th...

  20. Scaling features of the tribology of polymer brushes of increasing grafting density around the mushroom-to-brush transition

    Science.gov (United States)

    Mayoral, E.; Klapp, J.; Gama Goicochea, A.

    2017-01-01

    Nonequilibrium coarse-grained, dissipative particle dynamics simulations of complex fluids, made up of polymer brushes tethered to planar surfaces immersed in a solvent yield nonmonotonic behavior of the friction coefficient as a function of the polymer grating density on the substrates, Γ , while the viscosity shows a monotonically increasing dependence on Γ . This effect is shown to be independent of the degree of polymerization, N , and the size of the system. It arises from the composition and the structure of the first particle layer adjacent to each surface that results from the confinement of the fluid. Whenever such layers are made up of as close a proportion of polymer beads to solvent particles as there are in the fluid, the friction coefficient shows a minimum, while for disparate proportions the friction coefficient grows. At the mushroom-to-brush transition (MBT) the viscosity scales with an exponent that depends on the characteristic exponent of the MBT (6/5) and the solvent quality exponent (ν =0.5 , for θsolvent), but it is independent of the polymerization degree (N ). On the other hand, the friction coefficient at the MBT scales as μ ˜N6 /5 , while the grafting density at the MBT scales as Γ ˜N-6 /5 when friction is minimal, in agreement with previous scaling theories. We argue these aspects are the result of cooperative phenomena that have important implications for the understanding of biological brushes and the design of microfluidics devices, among other applications of current academic and industrial interest.

  1. The Dynamical Masses, Densities, and Star Formation Scaling Relations of Lyman Alpha Galaxies

    CERN Document Server

    Rhoads, James E; Finkelstein, Steven L; Fynbo, Johan P U; McLinden, Emily M; Richardson, Mark L A; Tilvi, Vithal S

    2013-01-01

    We present the first dynamical mass measurements for Lyman alpha galaxies at high redshift, based on velocity dispersion measurements from rest-frame optical emission lines and size measurements from HST imaging, for a sample of nine galaxies drawn from four surveys. These measurements enable us to study the nature of Lyman alpha galaxies in the context of galaxy scaling relations. The resulting dynamical masses range from 1e9 to 1e10 solar masses. We also fit stellar population models to our sample, and use them to plot the Lyman alpha sample on a stellar mass vs. line width relation. Overall, the Lyman alpha galaxies follow well the scaling relation established by observing star forming galaxies at lower redshift (and without regard for Lyman alpha emission), though in 1/3 of the Lyman alpha galaxies, lower-mass fits are also acceptable. In all cases, the dynamical masses agree with established stellarmass-linewidth relation. Using the dynamical masses as an upper limit on gas mass, we show that Lyman alpha...

  2. Scaling properties of the chiral phase transition in the low density region of two-flavor QCD with improved Wilson fermions

    CERN Document Server

    Umeda, T; Kanaya, K; Maezawa, Y; Nakagawa, Y; Ohno, H; Saito, H; Yoshida, S

    2013-01-01

    We study scaling behavior of a chiral order parameter in the low density region, performing a simulation of two-flavor QCD with improved Wilson quarks. The scaling behavior of the chiral order parameter defined by a Ward-Takahashi identity agrees with the scaling function of the three-dimensional O(4) spin model at zero chemical potential. We extend the scaling study to finite density QCD. Applying the reweighting method and calculating derivatives of the chiral order parameter with respect to the chemical potential, the scaling properties of the chiral phase transition are discussed in the low density region. We moreover calculate the curvature of the phase boundary of the chiral phase transition in the temperature and chemical potential plane assuming the O(4) scaling relation.

  3. The HI Content of Galaxies as a Function of Local Density and Large-Scale Environment

    Science.gov (United States)

    Thoreen, Henry; Cantwell, Kelly; Maloney, Erin; Cane, Thomas; Brough Morris, Theodore; Flory, Oscar; Raskin, Mark; Crone-Odekon, Mary; ALFALFA Team

    2017-01-01

    We examine the HI content of galaxies as a function of environment, based on a catalogue of 41527 galaxies that are part of the 70% complete Arecibo Legacy Fast-ALFA (ALFALFA) survey. We use nearest-neighbor methods to characterize local environment, and a modified version of the algorithm developed for the Galaxy and Mass Assembly (GAMA) survey to classify large-scale environment as group, filament, tendril, or void. We compare the HI content in these environments using statistics that include both HI detections and the upper limits on detections from ALFALFA. The large size of the sample allows to statistically compare the HI content in different environments for early-type galaxies as well as late-type galaxies. This work is supported by NSF grants AST-1211005 and AST-1637339, the Skidmore Faculty-Student Summer Research program, and the Schupf Scholars program.

  4. Bayesian inference of cosmic density fields from non-linear, scale-dependent, and stochastic biased tracers

    CERN Document Server

    Ata, Metin; Müller, Volker

    2014-01-01

    We present a Bayesian reconstruction algorithm to generate unbiased samples of the underlying dark matter field from galaxy redshift data. Our new contribution consists of implementing a non-Poisson likelihood including a deterministic non-linear and scale-dependent bias. In particular we present the Hamiltonian equations of motions for the negative binomial (NB) probability distribution function. This permits us to efficiently sample the posterior distribution function of density fields given a sample of galaxies using the Hamiltonian Monte Carlo technique implemented in the Argo code. We have tested our algorithm with the Bolshoi N-body simulation, inferring the underlying dark matter density field from a subsample of the halo catalogue. Our method shows that we can draw closely unbiased samples (compatible within 1-$\\sigma$) from the posterior distribution up to scales of about k~1 h/Mpc in terms of power-spectra and cell-to-cell correlations. We find that a Poisson likelihood yields reconstructions with p...

  5. Multi-scale Planck corrections to Herschel dust continuum emission maps: Implications for column density and temperature maps

    CERN Document Server

    Abreu-Vicente, J; Robitaille, T; Henning, Th; Keto, E

    2016-01-01

    We present a Fourier space method to combine the publicly available Herschel PACS and SPIRE data with the Planck thermal dust emission model. The method effectively combines the Planck large angular scale emission with the small scale \\herschel emission, similar to the feathering method used in interferometry and recently implemented by Csengeri et al. to correct the ground-based ATLASGAL data. This method eliminates the pervasive negative fluxes present in the PACS 160 micron archive data while preserving the structure in the background of both the PACS and SPIRE data. We generate column density and temperature maps from data calibrated with this method. We analyze the validity of our new method using star-forming regions in a range of environments: low-mass Bok Globules (B68), nearby star-forming regions (Perseus), and high-mass star forming regions in the Galactic plane (including IRDC G11 and W31). We accurately recover low column density material, comparing well to previous near-infrared extinction metho...

  6. High oxygen consumption rates and scale loss indicate elevated aggressive behaviour at low rearing density, while elevated brain serotonergic activity suggest chronic stress at high rearing densities in farmed rainbow trout Oncorhynchus mykiss

    DEFF Research Database (Denmark)

    Laursen, Danielle Caroline; Silva, P.I.M.; Larsen, Bodil Katrine;

    2013-01-01

    of a previous study,where levels of crowding where determined using the spatial distribution of fish in two-tank systems. An un-crowded low density of 25 kg m−3, the highest density accepted by the fish without showing indications of crowding stress of 80 kg m−3 as the intermediate density, and the highest...... density accepted by the fish showing indications of crowding stress of 140 kg m−3 as the high density were investigated. The aimof the present study was to examine the effect of being held at these densities on indicators of welfare. This was achieved through oxygen consumption measurements using...... automated respirometry, recording fin erosion, determining scale loss and analysing plasma cortisol and brain serotonergic activity levels. The results obtained in the present study indicated that at the lowest density the fish had the space and opportunity to display their natural aggressive behaviour...

  7. Density-scaling exponents and virial potential-energy correlation coefficients for the (2n, n) Lennard-Jones system

    Indian Academy of Sciences (India)

    IDA M FRIISBERG; LORENZO COSTIGLIOLA; JEPPE C DYRE

    2017-07-01

    This paper investigates the relation between the density-scaling exponent γ and the virial potential energy correlation coefficient R at several thermodynamic state points in three dimensions for the generalized (2n, n) Lennard-Jones (LJ) system for n = 4, 9, 12, 18, as well as for the standard n = 6 LJ system in two,three, and four dimensions. The state points studied include many low-density states at which the virial potential energy correlations are not strong. For these state points we find the roughly linear relation γ∼=3n R/d in d dimensions. This result is discussed in light of the approximate “extended inverse power law” description of generalized LJ potentials (Bailey N P et al. 2008 J. Chem. Phys. 129 184508). In the plot of γ versus R there is in all cases a transition around R ≈ 0.9, above which γ starts to decrease as R approaches unity. This is consistent with the fact that γ → 2n/d for R → 1, a limit that is approached at high densities and/or high temperatures at which the repulsive r−2n term dominates the physics.

  8. Effective homogeneity of the exchange-correlation and non-interacting kinetic energy functionals under density scaling.

    Science.gov (United States)

    Borgoo, Alex; Teale, Andrew M; Tozer, David J

    2012-01-21

    Correlated electron densities, experimental ionisation potentials, and experimental electron affinities are used to investigate the homogeneity of the exchange-correlation and non-interacting kinetic energy functionals of Kohn-Sham density functional theory under density scaling. Results are presented for atoms and small molecules, paying attention to the influence of the integer discontinuity and the choice of the electron affinity. For the exchange-correlation functional, effective homogeneities are highly system-dependent on either side of the integer discontinuity. By contrast, the average homogeneity-associated with the potential that averages over the discontinuity-is generally close to 4/3 when the discontinuity is computed using positive affinities for systems that do bind an excess electron and negative affinities for those that do not. The proximity to 4/3 becomes increasingly pronounced with increasing atomic number. Evaluating the discontinuity using a zero affinity in systems that do not bind an excess electron instead leads to effective homogeneities on the electron abundant side that are close to 4/3. For the non-interacting kinetic energy functional, the effective homogeneities are less system-dependent and the effect of the integer discontinuity is less pronounced. Average values are uniformly below 5/3. The study provides information that may aid the development of improved exchange-correlation and non-interacting kinetic energy functionals. © 2012 American Institute of Physics

  9. Simulating x-ray Thomson scattering signals from high-density, millimetre-scale plasmas at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, D. A., E-mail: david.chapman@awe.co.uk [Plasma Physics Group, Radiation Physics Department, AWE plc, Reading RG7 4PR (United Kingdom); Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry CV4 7AL (United Kingdom); Kraus, D.; Falcone, R. W. [Department of Physics, University of California, Berkeley, California 94720 (United States); Kritcher, A. L.; Bachmann, B.; Collins, G. W.; Gaffney, J. A.; Hawreliak, J. A.; Landen, O. L.; Le Pape, S.; Ma, T.; Nilsen, J.; Pak, A.; Swift, D. C.; Döppner, T. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Gericke, D. O. [Centre for Fusion, Space and Astrophysics, University of Warwick, Coventry CV4 7AL (United Kingdom); Glenzer, S. H. [SLAC National Accelerator Laboratory, Menlo Park, California 94309 (United States); Guymer, T. M. [Plasma Physics Group, Radiation Physics Department, AWE plc, Reading RG7 4PR (United Kingdom); Neumayer, P. [Gesellschaft für Schwerionenforschung, 64291 Darmstadt (Germany); Redmer, R. [Institut für Physik, Universität Rostock, 18051 Rostock (Germany); and others

    2014-08-15

    We have developed a model for analysing x-ray Thomson scattering data from high-density, millimetre-scale inhomogeneous plasmas created during ultra-high pressure implosions at the National Ignition Facility in a spherically convergent geometry. The density weighting of the scattered signal and attenuation of the incident and scattered x-rays throughout the target are included using radial profiles of the density, opacity, ionization state, and temperature provided by radiation-hydrodynamics simulations. These simulations show that the scattered signal is strongly weighted toward the bulk of the shocked plasma and the Fermi degenerate material near the ablation front. We show that the scattered signal provides a good representation of the temperature of this highly nonuniform bulk plasma and can be determined to an accuracy of ca. 15% using typical data analysis techniques with simple 0D calculations. On the other hand, the mean ionization of the carbon in the bulk is underestimated. We suggest that this discrepancy is due to the convolution of scattering profiles from different regions of the target. Subsequently, we discuss modifications to the current platform to minimise the impact of inhomogeneities, as well as opacity, and also to enable probing of conditions more strongly weighted toward the compressed core.

  10. Scaling of surface-plasma reactors with a significantly increased energy density for NO conversion.

    Science.gov (United States)

    Malik, Muhammad Arif; Xiao, Shu; Schoenbach, Karl H

    2012-03-30

    Comparative studies revealed that surface plasmas developing along a solid-gas interface are significantly more effective and energy efficient for remediation of toxic pollutants in air than conventional plasmas propagating in air. Scaling of the surface plasma reactors to large volumes by operating them in parallel suffers from a serious problem of adverse effects of the space charges generated at the dielectric surfaces of the neighboring discharge chambers. This study revealed that a conductive foil on the cathode potential placed between the dielectric plates as a shield not only decoupled the discharges, but also increased the electrical power deposited in the reactor by a factor of about forty over the electrical power level obtained without shielding and without loss of efficiency for NO removal. The shield had no negative effect on efficiency, which is verified by the fact that the energy costs for 50% NO removal were about 60 eV/molecule and the energy constant, k(E), was about 0.02 L/J in both the shielded and unshielded cases.

  11. Childhood height, adult height, and the risk of prostate cancer

    DEFF Research Database (Denmark)

    Bjerregaard, Lise Geisler; Aarestrup, Julie; Gamborg, Michael;

    2016-01-01

    PURPOSE: We previously showed that childhood height is positively associated with prostate cancer risk. It is, however, unknown whether childhood height exerts its effects independently of or through adult height. We investigated whether and to what extent childhood height has a direct effect...... on the risk of prostate cancer apart from adult height. METHODS: We included 5,871 men with height measured at ages 7 and 13 years in the Copenhagen School Health Records Register who also had adult (50-65 years) height measured in the Danish Diet, Cancer and Health study. Prostate cancer status was obtained...... through linkage to the Danish Cancer Registry. Direct and total effects of childhood height on prostate cancer risk were estimated from Cox regressions. RESULTS: From 1996 to 2012, 429 prostate cancers occurred. Child and adult heights were positively and significantly associated with prostate cancer risk...

  12. Analysis of Tubespins as a suitable scale-down model of bioreactors for high cell density CHO cell culture.

    Science.gov (United States)

    Gomez, Natalia; Ambhaikar, Malhar; Zhang, Li; Huang, Chung-Jr; Barkhordarian, Hedieh; Lull, Jonathan; Gutierrez, Chris

    2017-03-01

    High cell density (HCD) culture increases recombinant protein productivity via higher biomass. Compared to traditional fed-batch cultures, HCD is achieved by increased nutrient availability and removal of undesired metabolic components via regular medium replenishment. HCD process development is usually performed in instrumented lab-scale bioreactors (BR) that require time and labor for setup and operation. To potentially minimize resources and cost during HCD experiments, we evaluated a 2-week 50-mL Tubespin (TS) simulated HCD process where daily medium exchanges mimic the medium replacement rate in BR. To best assess performance differences, we cultured 13 different CHO cell lines in simulated HCD as satellites from simultaneous BR, and compared growth, metabolism, productivity and product quality. Overall, viability, cell-specific productivity and metabolism in TS were comparable to BR, but TS cell growth and final titer were lower by 25 and 15% in average, respectively. Peak viable cell densities were lower in TS than BR as a potential consequence of lower pH, different medium exchange strategy and dissolved oxygen limitations. Product quality attributes highly dependent on intrinsic molecule or cell line characteristics (e.g., galactosylation, afucosylation, aggregation) were comparable in both scales. However, product quality attributes that can change extracellularly as a function of incubation time (e.g., deamidation, C-terminal lysine, fragmentation) were in general lower in TS because of shorter residence time than HCD BR. Our characterization results and two case studies show that TS-simulated HCD cultures can be effectively used as a simple scale-down model for relative comparisons among cell lines for growth or productivity (e.g., clone screening), and for investigating effects on protein galactosylation. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:490-499, 2017. © 2017 American Institute of Chemical Engineers.

  13. Roles of Spatial Scale and Rarity on the Relationship between Butterfly Species Richness and Human Density in South Africa: e0124327

    National Research Council Canada - National Science Library

    Silvia Mecenero; Res Altwegg; Jonathan F Colville; Colin M Beale

    2015-01-01

    .... Species richness is often positively correlated with human population density at broad scales, but this correlation could also be caused by unequal sampling effort leading to higher species tallies...

  14. Density functional theory studies on the nano-scaled composites consisted of graphene and acyl hydrazone molecules

    Science.gov (United States)

    Ren, J. L.; Zhou, L.; Lv, Z. C.; Ding, C. H.; Wu, Y. H.; Bai, H. C.

    2016-07-01

    Graphene, which is the first obtained single atomic layer 2D materials, has drawn a great of concern in nano biotechnology due to the unique property. On one hand, acyl hydrazone compounds belonging to the Schif bases have aroused considerable attention in medicine, pharmacy, and analytical reagent. However, few understanding about the interaction between graphene and acyl hydrazone molecules is now available. And such investigations are much crucial for the applications of these new nano-scaled composites. The current work revealed theoretical investigations on the nano-scaled composites built by acyl hydrazone molecules loaded on the surface of graphene. The relative energy, electronic property and the interaction between the counterparts of graphene/acyl hydrazone composites are investigated based on the density functional theory calculations. According to the obtained adsorption energy, the formation of the nano-scaled composite from the isolated graphene and acyl hydrazone molecule is exothermic, and thus it is energetically favorable to form these nano composites in viewpoint of total energy change. The frontier molecular orbital for the nano composite is mainly distributed at the graphene part, leading to that the energy levels of the frontier molecular orbital of the nano composites are very close to that of isolated graphene. Moreover, the counterpart interaction for the graphene/acyl hydrazone composites is also explored based on the discussions of orbital hybridization, charge redistribution and Van der Waals interaction.

  15. Ejecta velocity distribution of impact craters formed on quartz sand: Effect of projectile density on crater scaling law

    Science.gov (United States)

    Tsujido, Sayaka; Arakawa, Masahiko; Suzuki, Ayako I.; Yasui, Minami

    2015-12-01

    In order to clarify the effects of projectile density on ejecta velocity distributions for a granular target, impact cratering experiments on a quartz sand target were conducted by using eight types of projectiles with different densities ranging from 11 g cm-3 to 1.1 g cm-3, which were launched at about 200 m s-1 from a vertical gas gun at Kobe University. The scaling law of crater size, the ejection angle of ejecta grains, and the angle of the ejecta curtain were also investigated. The ejecta velocity distribution obtained from each projectile was well described by the π-scaling theory of v0/√{gR} =k2(x0/R)-1/μ, where v0, g, R and x0 are the ejection velocity, gravitational acceleration, crater radius and ejection position, respectively, and k2 and μ are constants mostly depending on target material properties (Housen, K.R., Holsapple, K.A. [2011]. Icarus 211, 856-875). The value of k2 was found to be almost constant at 0.7 for all projectiles except for the nylon projectile, while μ increased with the projectile density, from 0.43 for the low-density projectile to 0.6-0.7 for the high-density projectile. On the other hand, the π-scaling theory for crater size gave a μ value of 0.57, which was close to the average of the μ values obtained from ejecta velocity distributions. The ejection angle, θ, of each grain decreased slightly with distance, from higher than 45° near the impact point to 30-40° at 0.6 R. The ejecta curtain angle is controlled by the two elementary processes of ejecta velocity distribution and ejection angle; it gradually increased from 52° to 63° with the increase of the projectile density. The comparison of our experimental results with the theoretical model of the crater excavation flow known as the Z-model revealed that the relationship between μ and θ obtained by our experiments could not be described by the Z-model (Maxwell, D.E. [1977]. In: Roddy, D.J., Pepin, R.O., Merrill, R.B. (Eds.), Impact and Explosion Cratering

  16. Optimization of Truss Height

    Directory of Open Access Journals (Sweden)

    Tomas Ulitinas

    2011-04-01

    Full Text Available The article analyzes the task in truss height and in the optimization of the cross-sections of their elements. Element cross-sections are designed of steel profiles considering requirements for strength, stability and rigidity. A mathematical model is formulated as a nonlinear mathematical programming problem. It is solved as an iterative process, using mathematical software package “MATLAB” routine “fmincon”. The ratio of buckling is corrected in the each iteration. Optimization results are compared with those obtained applying software package “Robot Millennium”.Article in Lithuanian

  17. Introducing PROFESS 2.0: A parallelized, fully linear scaling program for orbital-free density functional theory calculations

    Science.gov (United States)

    Hung, Linda; Huang, Chen; Shin, Ilgyou; Ho, Gregory S.; Lignères, Vincent L.; Carter, Emily A.

    2010-12-01

    Orbital-free density functional theory (OFDFT) is a first principles quantum mechanics method to find the ground-state energy of a system by variationally minimizing with respect to the electron density. No orbitals are used in the evaluation of the kinetic energy (unlike Kohn-Sham DFT), and the method scales nearly linearly with the size of the system. The PRinceton Orbital-Free Electronic Structure Software (PROFESS) uses OFDFT to model materials from the atomic scale to the mesoscale. This new version of PROFESS allows the study of larger systems with two significant changes: PROFESS is now parallelized, and the ion-electron and ion-ion terms scale quasilinearly, instead of quadratically as in PROFESS v1 (L. Hung and E.A. Carter, Chem. Phys. Lett. 475 (2009) 163). At the start of a run, PROFESS reads the various input files that describe the geometry of the system (ion positions and cell dimensions), the type of elements (defined by electron-ion pseudopotentials), the actions you want it to perform (minimize with respect to electron density and/or ion positions and/or cell lattice vectors), and the various options for the computation (such as which functionals you want it to use). Based on these inputs, PROFESS sets up a computation and performs the appropriate optimizations. Energies, forces, stresses, material geometries, and electron density configurations are some of the values that can be output throughout the optimization. New version program summaryProgram Title: PROFESS Catalogue identifier: AEBN_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEBN_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 68 721 No. of bytes in distributed program, including test data, etc.: 1 708 547 Distribution format: tar.gz Programming language: Fortran 90 Computer

  18. Electrostatic Interactions in Finite Systems treated with Periodic Boundary Conditions: Application to Linear-Scaling Density Functional Theory

    CERN Document Server

    Hine, N D M; Haynes, P D; Skylaris, C K

    2011-01-01

    We present a comparison of methods for treating the electrostatic interactions of finite, isolated systems within periodic boundary conditions (PBCs), within Density Functional Theory (DFT), with particular emphasis on linear-scaling (LS) DFT. Often, PBCs are not physically realistic but are an unavoidable consequence of the choice of basis set and the efficacy of using Fourier transforms to compute the Hartree potential. In such cases the effects of PBCs on the calculations need to be avoided, so that the results obtained represent the open rather than the periodic boundary. The very large systems encountered in LS-DFT make the demands of the supercell approximation for isolated systems more difficult to manage, and we show cases where the open boundary (infinite cell) result cannot be obtained from extrapolation of calculations from periodic cells of increasing size. We discuss, implement and test three very different approaches for overcoming or circumventing the effects of PBCs: truncation of the Coulomb ...

  19. Negative electron affinities from DFT: influence of asymptotic exchange-correlation potential and effective homogeneity under density scaling.

    Science.gov (United States)

    Borgoo, Alex; Tozer, David J

    2012-06-07

    The influence of the asymptotic exchange-correlation potential and density-scaling homogeneity on negative electron affinities determined using the approach of Tozer and De Proft [J. Phys. Chem. A2005, 109, 8923] is investigated. Application of an asymptotic correction to the potential improves the accuracy for several of the systems with the most negative affinities, reflecting their diffuse lowest unoccupied orbitals. For systems with modest affinities, it reduces the accuracy marginally. Enforcing a near-exact effective homogeneity through a simple shift in the potential leads to improved correlation with experimental values but significantly overestimated affinities. Optimal effective homogeneities are therefore determined, and a simple scheme is proposed for enforcing an average optimal value. Application of the scheme to a series of organic molecules maintains the excellent correlation with the experimental values while significantly reducing the absolute errors.

  20. A low cost, high energy density and long cycle life potassium-sulfur battery for grid-scale energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Xiaochuan; Bowden, Mark E.; Sprenkle, Vincent L.; Liu, Jun

    2015-08-15

    Alkali metal-sulfur batteries are attractive for energy storage applications because of their high energy density. Among the batteries, lithium-sulfur batteries typically use liquid in the battery electrolyte, which causes problems in both performance and safety. Sodium-sulfur batteries can use a solid electrolyte such as beta alumina but this requires a high operating temperature. Here we report a novel potassium-sulfur battery with K+-conducting beta-alumina as the electrolyte. Our studies indicate that liquid potassium exhibits much better wettability on the surface of beta-alumina compared to liquid sodium at lower temperatures. Based on this observation, we develop a potassium-sulfur battery that can operate at as low as 150°C with excellent performance. In particular, the battery shows excellent cycle life with negligible capacity fade in 1000 cycles because of the dense ceramic membrane. This study demonstrates a new battery with a high energy density, long cycle life, low cost and high safety, which is ideal for grid-scale energy storage.

  1. Evaluation of defect density by top-view large scale AFM on metamorphic structures grown by MOVPE

    Energy Technology Data Exchange (ETDEWEB)

    Gocalinska, Agnieszka, E-mail: agnieszka.gocalinska@tyndall.ie; Manganaro, Marina; Dimastrodonato, Valeria; Pelucchi, Emanuele

    2015-09-15

    Highlights: • Metamorphic buffer layers of In{sub x}Ga{sub 1−x}As were grown by MOVPE and characterised by AFM and TEM. • It was found that AFM provides sufficient information to estimate threading defect density in metamorphic structures, even when significant roughness is present. • When planar-view TEM is lacking, a combination of cross-sectional TEM and large scale AFM can provide good evaluation of the material quality. • It is fast, cheap and non-destructive – can be very useful in development process of complicated structures, requiring multiple test growths and characterisation. - Abstract: We demonstrate an atomic force microscopy based method for estimation of defect density by identification of threading dislocations on a non-flat surface resulting from metamorphic growth. The discussed technique can be applied as an everyday evaluation tool for the quality of epitaxial structures and allow for cost reduction, as it lessens the amount of the transmission electron microscopy analysis required at the early stages of projects. Metamorphic structures with low surface defectivities (below 10{sup 6}) were developed successfully with the application of the technique, proving its usefulness in process optimisation.

  2. The limiting distribution of the maximal height of the outermost path of nonintersecting Brownian excursions and discrete Gaussian orthogonal polynomials

    CERN Document Server

    Liechty, Karl

    2011-01-01

    We study the distribution of the maximal height of the outermost path in the model of $N$ nonintersecting Brownian excursions as $N\\to \\infty$, showing that it converges in the proper scaling to the Tracy-Widom distribution for the largest eigenvalue of the Gaussian orthogonal ensemble. This is as expected from the viewpoint that the maximal height of the outermost path converges to the maximum of the Airy process. Our proof is based on Riemann-Hilbert analyis of a system of discrete orthogonal polynomials with a Gaussian weight in the double scaling limit as this system approaches saturation. We consequently compute the asymptotics of the free energy and the reproducing kernel of the corresponding discrete orthogonal polynomial ensemble in the critical scaling in which the density of particles approaches saturation. Both of these results can be viewed as dual to the case in which the mean density of eigenvalues in a random matrix model is vanishing at one point.

  3. Astrophysical implications of the neutrino rest mass. II. The density-perturbation spectrum and small-scale fluctuations in the microwave background

    Energy Technology Data Exchange (ETDEWEB)

    Doroshkevich, A.G.; Zel' dovich, Y.B.; Syunyaev, R.A.; Khlopov, M.Y.

    1980-07-01

    If the neutrino has a rest mass, a scale comparable with the distance between clusters of galaxies would have been singled out in the universe. The amplitude of neutrino density perturbations on smaller scales should diminish in proportion to a high power of the perturbation wavelength. The evolution of adiabatic and entropic (isothermal) density perturbations is considered, and it is shown that the existence of a neutrino rest mass would imply smaller fine-scale fluctuations in the microwave background radiation than models in which m/sub ..nu../=0.

  4. Pyroclastic density current hazard maps at Campi Flegrei caldera (Italy): the effects of event scale, vent location and time forecasts.

    Science.gov (United States)

    Bevilacqua, Andrea; Neri, Augusto; Esposti Ongaro, Tomaso; Isaia, Roberto; Flandoli, Franco; Bisson, Marina

    2016-04-01

    Today hundreds of thousands people live inside the Campi Flegrei caldera (Italy) and in the adjacent part of the city of Naples making a future eruption of such volcano an event with huge consequences. Very high risks are associated with the occurrence of pyroclastic density currents (PDCs). Mapping of background or long-term PDC hazard in the area is a great challenge due to the unknown eruption time, scale and vent location of the next event as well as the complex dynamics of the flow over the caldera topography. This is additionally complicated by the remarkable epistemic uncertainty on the eruptive record, affecting the time of past events, the location of vents as well as the PDCs areal extent estimates. First probability maps of PDC invasion were produced combining a vent-opening probability map, statistical estimates concerning the eruptive scales and a Cox-type temporal model including self-excitement effects, based on the eruptive record of the last 15 kyr. Maps were produced by using a Monte Carlo approach and adopting a simplified inundation model based on the "box model" integral approximation tested with 2D transient numerical simulations of flow dynamics. In this presentation we illustrate the independent effects of eruption scale, vent location and time of forecast of the next event. Specific focus was given to the remarkable differences between the eastern and western sectors of the caldera and their effects on the hazard maps. The analysis allowed to identify areas with elevated probabilities of flow invasion as a function of the diverse assumptions made. With the quantification of some sources of uncertainty in relation to the system, we were also able to provide mean and percentile maps of PDC hazard levels.

  5. Landscape-scale GPP and carbon density inform patterns and impacts of an invasive tree across wet forests of Hawaii.

    Science.gov (United States)

    Barbosa, Jomar M; Asner, Gregory P; Hughes, R Flint; Johnson, M Tracy

    2017-03-01

    Plant invasion typically occurs within a landscape-scale framework of abiotic and biotic conditions, often resulting in emergent feedbacks among environment, ecosystem functions, and the dominance of invasive species. Understanding the mechanisms underlying successful invasions is an important component of conservation and management efforts, but this has been poorly investigated in a spatially explicit manner. Knowing where and why invasion patterns change throughout the landscape enables managers to use context-specific controls on the spread of invasive species. Using high-resolution airborne imaging spectroscopy, we studied plant performance in growth within and across landscapes to examine the dominance and spatial distribution of an invasive tree, Psidium cattleianum (strawberry guava), in heterogeneous environmental conditions of a submontane Hawaiian tropical forest. We assessed invader performance using the GPP ratio index, which is the relative difference in remotely sensed estimates of gross primary productivity between canopies of guava and canopies of the invaded plant community. In addition, we used airborne LiDAR data to evaluate the impacts of guava invasion on the forest aboveground carbon density in different environments. Structural equation modeling revealed that substrate type and elevation above sea level interact and amplify landscape-scale differences in productivity between the invasive species and the host plant community (GPP ratio); differences that ultimately control levels of dominance of guava. We found shifts in patterns of forest carbon storage based on both gradual increase of invader dominance and changes in environmental conditions. Overall, our results demonstrate that the remotely sensed index defined as the GPP ratio provided an innovative spatially explicit approach to track and predict the success of invasive plants based in their canopy productivity, particularly within a landscape-scale framework of varying environmental

  6. A density matrix-based method for the linear-scaling calculation of dynamic second- and third-order properties at the Hartree-Fock and Kohn-Sham density functional theory levels.

    Science.gov (United States)

    Kussmann, Jörg; Ochsenfeld, Christian

    2007-11-28

    A density matrix-based time-dependent self-consistent field (D-TDSCF) method for the calculation of dynamic polarizabilities and first hyperpolarizabilities using the Hartree-Fock and Kohn-Sham density functional theory approaches is presented. The D-TDSCF method allows us to reduce the asymptotic scaling behavior of the computational effort from cubic to linear for systems with a nonvanishing band gap. The linear scaling is achieved by combining a density matrix-based reformulation of the TDSCF equations with linear-scaling schemes for the formation of Fock- or Kohn-Sham-type matrices. In our reformulation only potentially linear-scaling matrices enter the formulation and efficient sparse algebra routines can be employed. Furthermore, the corresponding formulas for the first hyperpolarizabilities are given in terms of zeroth- and first-order one-particle reduced density matrices according to Wigner's (2n+1) rule. The scaling behavior of our method is illustrated for first exemplary calculations with systems of up to 1011 atoms and 8899 basis functions.

  7. On the observability of bottom topography from measurements of tidal sea surface height

    Science.gov (United States)

    Zaron, Edward D.

    2016-06-01

    The question of whether features of the ocean bottom topography can be identified from measurements of water level is investigated using a simplified one-dimensional barotropic model. Because of the nonlinear dependence of the sea surface height on the water depth, a linearized analysis is performed concerning the identification of a Gaussian bump within two specific depth profiles, (1) a constant depth domain, and, (2) a constant depth domain adjoining a near-resonant continental shelf. Observability is quantified by examining the estimation error in a series of identical-twin experiments varying data density, tide wavelength, assumed (versus actual) topographic correlation scale, and friction. For measurements of sea surface height that resolve the scale of the topographic perturbation, the fractional error in the bottom topography is approximately a factor of 10 larger than the fractional error of the sea surface height. Domain-scale and shelf-scale resonances may lead to inaccurate topography estimates due to a reduction in the effective number of degrees of freedom in the dynamics, and the amplification of nonlinearity. A realizability condition for the variance of the topography error in the limit of zero bottom depth is proposed which is interpreted as a bound on the fractional error of the topography. Appropriately designed spatial covariance models partly ameliorate the negative impact of shelf-scale near-resonance, and highlight the importance of spatial covariance modeling for bottom topography estimation.

  8. An investigation of ionospheric upper transition height variations at low and equatorial latitudes deduced from combined COSMIC and C/NOFS measurements

    Science.gov (United States)

    Yang, Changjun; Zhao, Biqiang; Zhu, Jie; Yue, Xinan; Wan, Weixing

    2017-10-01

    In this study we propose the combination of topside in-situ ion density data from the Communication/Navigation Outage Forecast System (C/NOFS) along with the electron density profile measurement from Constellation Observing System for Meteorology, Ionosphere & Climate (COSMIC) satellites Radio Occultation (RO) for studying the spatial and temporal variations of the ionospheric upper transition height (hT) and the oxygen ion (O+) density scale height. The latitudinal, local time and seasonal distributions of upper transition height show more consistency between hT re-calculated by the profile of the O+ using an α-Chapman function with linearly variable scale height and that determined from direct in-situ ion composition measurements, than with constant scale height and only the COSMIC data. The discrepancy in the values of hT between the C/NOFS measurement and that derived by the combination of COSMIC and C/NOFS satellites observations with variable scale height turns larger as the solar activity decreases, which suggests that the photochemistry and the electrodynamics of the equatorial ionosphere during the extreme solar minimum period produce abnormal structures in the vertical plasma distribution. The diurnal variation of scale heights (Hm) exhibits a minimum after sunrise and a maximum around noon near the geomagnetic equator. Further, the values of Hm exhibit a maximum in the summer hemisphere during daytime, whereas in the winter hemisphere the maximum is during night. Those features of Hm consistently indicate the prominent role of the vertical electromagnetic (E × B) drift in the equatorial ionosphere.

  9. Combinação da altura de desponte e do espaçamento entre plantas de tomate Combination of planting densities with top lopping heights of tomato plants

    Directory of Open Access Journals (Sweden)

    Siegfried Mueller

    2009-03-01

    Full Text Available Em trabalhos a campo realizados na Epagri, Estação Experimental de Caçador (SC, durante as safras de 1998/1999, 1999/2000 e 2000/2001, estudou-se a interação entre quatro alturas de desponta (acima do 5º, 7º, 9º e 11º cachos e quatro espaçamentos entre plantas (0,30; 0,45; 0,60 e 0,75 m, de plantas de tomate cv. Diva. O espaçamento entre fileiras foi de 1,0 m para todos os tratamentos e anos estudados. O delineamento experimental foi de blocos completos ao acaso, em um fatorial 4 x 4, com três repetições. As plantas foram tutoradas em 'V' invertido empregando-se varas de bambu (taquaruçú como tutores. Foram avaliados a produtividade e o número de frutos total e comercial, a percentagem e a massa média de frutos comercial, a altura de plantas e o diâmetro da base do caule. O aumento do espaçamento de plantas reduziu a altura das plantas, o número e a produtividade de frutos comercial e total, porém proporcionou aumento do diâmetro do caule e da massa média dos frutos comerciais. Por sua vez, o aumento do número de cachos por planta aumentou a altura das plantas, o número e a produtividade de frutos comercial e total. Entretanto, o diâmetro do caule e a massa média dos frutos comerciais diminuíram com o aumento do número de cachos por planta.Three field experiments were carried out in Caçador, Santa Catarina State, Brazil, during 1998/1999, 1999/2000 and 2000/2001 seasons to study four lopping heights of the tops (above the 5th, 7th, 9th, and 11th clusters and four-plant spacings between plants (0.30; 0.45; 0.60, and 0.75 m. Plant spacing between rows of tomato cv. Diva was of 1.0 m, in all studied treatments and years of the research. Experiments were designed in randomized blocks, with three replicates in a factorial scheme (4 x 4. Plants were staked as crossed fence, using bamboo sticks as tutors. The yield, number of fruits, percentage and average weight of marketable fruits, plant height and stem base diameter

  10. High-performance ab initio density matrix renormalization group method: Applicability to large-scale multireference problems for metal compounds

    Science.gov (United States)

    Kurashige, Yuki; Yanai, Takeshi

    2009-06-01

    This article presents an efficient and parallelized implementation of the density matrix renormalization group (DMRG) algorithm for quantum chemistry calculations. The DMRG method as a large-scale multireference electronic structure model is by nature particularly efficient for one-dimensionally correlated systems, while the present development is oriented toward applications for polynuclear transition metal compounds, in which the macroscopic one-dimensional structure of electron correlation is absent. A straightforward extension of the DMRG algorithm is proposed with further improvements and aggressive optimizations to allow its application with large multireference active space, which is often demanded for metal compound calculations. Special efficiency is achieved by making better use of sparsity and symmetry in the operator and wave function representations. By accomplishing computationally intensive DMRG calculations, the authors have found that a large number of renormalized basis states are required to represent high entanglement of the electron correlation for metal compound applications, and it is crucial to adopt auxiliary perturbative correction to the projected density matrix during the DMRG sweep optimization in order to attain proper convergence to the solution. Potential energy curve calculations for the Cr2 molecule near the known equilibrium precisely predicted the full configuration interaction energies with a correlation space of 24 electrons in 30 orbitals [denoted by (24e,30o)]. The energies are demonstrated to be accurate to 0.6mEh (the error from the extrapolated best value) when as many as 10 000 renormalized basis states are employed for the left and right DMRG block representations. The relative energy curves for [Cu2O2]2+ along the isomerization coordinate were obtained from DMRG and other correlated calculations, for which a fairly large orbital space (32e,62o) is modeled as a full correlation space. The DMRG prediction nearly overlaps

  11. Quantum information density scaling and qubit operation time constraints of CMOS silicon-based quantum computer architectures

    Science.gov (United States)

    Rotta, Davide; Sebastiano, Fabio; Charbon, Edoardo; Prati, Enrico

    2017-06-01

    range of a silicon complementary metal-oxide-semiconductor quantum processor to be within 1 and 100 GHz. Such constraint limits the feasibility of fault-tolerant quantum information processing with complementary metal-oxide-semiconductor technology only to the most advanced nodes. The compatibility with classical complementary metal-oxide-semiconductor control circuitry is discussed, focusing on the cryogenic complementary metal-oxide-semiconductor operation required to bring the classical controller as close as possible to the quantum processor and to enable interfacing thousands of qubits on the same chip via time-division, frequency-division, and space-division multiplexing. The operation time range prospected for cryogenic control electronics is found to be compatible with the operation time expected for qubits. By combining the forecast of the development of scaled technology nodes with operation time and classical circuitry constraints, we derive a maximum quantum information density for logical qubits of 2.8 and 4 Mqb/cm2 for the 10 and 7-nm technology nodes, respectively, for the Steane code. The density is one and two orders of magnitude less for surface codes and for concatenated codes, respectively. Such values provide a benchmark for the development of fault-tolerant quantum algorithms by circuital quantum information based on silicon platforms and a guideline for other technologies in general.

  12. Linear-Scaling Time-Dependent Density Functional Theory Based on the Idea of "From Fragments to Molecule".

    Science.gov (United States)

    Wu, Fangqin; Liu, Wenjian; Zhang, Yong; Li, Zhendong

    2011-11-08

    To circumvent the cubic scaling and convergence difficulties encountered in the standard top-down localization of the global canonical molecular orbitals (CMOs), a bottom-up localization scheme is proposed based on the idea of "from fragments to molecule". That is, the global localized MOs (LMOs), both occupied and unoccupied, are to be synthesized from the primitive fragment LMOs (pFLMOs) obtained from subsystem calculations. They are orthonormal but are still well localized on the parent fragments of the pFLMOs and can hence be termed as "fragment LMOs" (FLMOs). This has been achieved by making use of two important factors. Physically, it is the transferability of the locality of the fragments that serves as the basis. Mathematically, it is the special block-diagonalization of the Kohn-Sham matrix that allows retention of the locality: The occupied-occupied and virtual-virtual diagonal blocks are only minimally modified when the occupied-virtual off-diagonal blocks are annihilated. Such a bottom-up localization scheme is applicable to systems composed of all kinds of chemical bonds. It is then shown that, by a simple prescreening of the particle-hole pairs, the FLMO-based time-dependent density functional theory (TDDFT) can achieve linear scaling with respect to the system size, with a very small prefactor. As a proof of principle, representative model systems are taken as examples to demonstrate the accuracy and efficiency of the algorithms. As both the orbital picture and integral number of electrons are retained, the FLMO-TDDFT offers a clear characterization of the nature of the excited states in line with chemical/physical intuition.

  13. Cognitive processing and acrophobia: validating the Heights Interpretation Questionnaire.

    Science.gov (United States)

    Steinman, Shari A; Teachman, Bethany A

    2011-10-01

    Three studies were conducted to examine the psychometric properties of a new scale: the Heights Interpretation Questionnaire (HIQ). This scale was designed to measure height fear-relevant interpretation bias to help assess the relationship between biased interpretations and acrophobia symptoms. Studies 1 (N=553) and 2 (N=308) established the scale's factor structure and convergent and discriminant validity among two large undergraduate samples. Study 3 (N=48) evaluated the predictive validity of the HIQ by examining how well the scale predicted subjective distress and avoidance on actual heights. Factor analysis resulted in four distinct factors, and results suggest that each of the factors, along with the full HIQ, have good reliability and validity. Additionally, the scale predicts subjective distress and avoidance on heights beyond self-reported acrophobia symptoms. Overall, the HIQ shows promise as a new tool to investigate cognitive processing biases in acrophobia. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. CLUMPING AND THE INTERPRETATION OF kpc-SCALE MAPS OF THE INTERSTELLAR MEDIUM: SMOOTH H I AND CLUMPY, VARIABLE H{sub 2} SURFACE DENSITY

    Energy Technology Data Exchange (ETDEWEB)

    Leroy, Adam K. [National Radio Astronomy Observtory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Lee, Cheoljong [Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22904 (United States); Schruba, Andreas [California Institute for Technology, 1200 E California Blvd, Pasadena, CA 91125 (United States); Bolatto, Alberto [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Hughes, Annie; Sandstrom, Karin; Schinnerer, Eva; Walter, Fabian [Max Planck Institute fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Pety, Jerome [Institut de Radioastronomie Millimetrique, 300 Rue de la Piscine, F-38406 Saint Martin d' Heres (France)

    2013-05-20

    Many recent models consider the structure of individual interstellar medium (ISM) clouds as a way to explain observations of large parts of galaxies. To compare such models to observations, one must understand how to translate between surface densities observed averaging over large ({approx}kpc) scales and surface densities on the scale of individual clouds ({approx}pc scale), which are treated by models. We define a ''clumping factor'' that captures this translation as the ratio of the mass-weighted surface density, which is often the quantity of physical interest, to the area-weighted surface density, which is observed. We use high spatial resolution (sub-kpc) maps of CO and H I emission from nearby galaxies to measure the clumping factor of both atomic and molecular gas. The molecular and atomic ISM exhibit dramatically different degrees of clumping. As a result, the ratio H{sub 2}/H I measured at {approx}kpc resolution cannot be trivially interpreted as a cloud-scale ratio of surface densities. H I emission appears very smooth, with a clumping factor of only {approx}1.3. Based on the scarce and heterogeneous high-resolution data available, CO emission is far more clumped with a widely variable clumping factor, median {approx}7 for our heterogeneous data. Our measurements do not provide evidence for a universal mass-weighted surface density of molecular gas, but also cannot conclusively rule out such a scenario. We suggest that a more sophisticated treatment of molecular ISM structure, one informed by high spatial resolution CO maps, is needed to link cloud-scale models to kpc-scale observations of galaxies.

  15. The application of APTEA experiment design to the experiment for determining information density of large scale display panel

    Energy Technology Data Exchange (ETDEWEB)

    Sim, Bong Sik; Oh, In Suk; Cha, Kyung Ho; Lee, Hyun Cheol [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1995-06-01

    APTEA experiment design was developed for the purpose of enhancing the availability of integrated test facility in 1994, and is composed of 5 phases including 28 contents. We applied APTEA experiment design to a preliminary human factors experiment for the determination of information density on a large scale display panel in order to confirm the usability of APTEA before utilizing it with integrated test facility. As results, we verified the easiness on the use of APTEA experiment design and identified points to be considered as follows. - Each phase and content doesn`t demand the same duration and level of work. Therefore it is unnecessary for experimenter to give same weight to all the phases and contents. - Filling up the phases and contents of ATPEA require various knowledge such as programming, human factors principles, experiment design. So a multidisciplinary team is desired in using APTEA experiment design. - It will be difficult to clearly discern the differences among contents in some experiments. In this case, the integration of several contents is desirable. 5 tabs., 2 figs., 5 refs. (Author) .new.

  16. Accurate localized resolution of identity approach for linear-scaling hybrid density functionals and for many-body perturbation theory

    Science.gov (United States)

    Ihrig, Arvid Conrad; Wieferink, Jürgen; Zhang, Igor Ying; Ropo, Matti; Ren, Xinguo; Rinke, Patrick; Scheffler, Matthias; Blum, Volker

    2015-09-01

    A key component in calculations of exchange and correlation energies is the Coulomb operator, which requires the evaluation of two-electron integrals. For localized basis sets, these four-center integrals are most efficiently evaluated with the resolution of identity (RI) technique, which expands basis-function products in an auxiliary basis. In this work we show the practical applicability of a localized RI-variant (‘RI-LVL’), which expands products of basis functions only in the subset of those auxiliary basis functions which are located at the same atoms as the basis functions. We demonstrate the accuracy of RI-LVL for Hartree-Fock calculations, for the PBE0 hybrid density functional, as well as for RPA and MP2 perturbation theory. Molecular test sets used include the S22 set of weakly interacting molecules, the G3 test set, as well as the G2-1 and BH76 test sets, and heavy elements including titanium dioxide, copper and gold clusters. Our RI-LVL implementation paves the way for linear-scaling RI-based hybrid functional calculations for large systems and for all-electron many-body perturbation theory with significantly reduced computational and memory cost.

  17. The potential of imogolite nanotubes as (co-)photocatalysts: a linear-scaling density functional theory study

    Science.gov (United States)

    Poli, E.; Elliott, J. D.; Ratcliff, L. E.; Andrinopoulos, L.; Dziedzic, J.; Hine, N. D. M.; Mostofi, A. A.; Skylaris, C.-K.; Haynes, P. D.; Teobaldi, G.

    2016-02-01

    We report a linear-scaling density functional theory (DFT) study of the structure, wall-polarization absolute band-alignment and optical absorption of several, recently synthesized, open-ended imogolite (Imo) nanotubes (NTs), namely single-walled (SW) aluminosilicate (AlSi), SW aluminogermanate (AlGe), SW methylated aluminosilicate (AlSi-Me), and double-walled (DW) AlGe NTs. Simulations with three different semi-local and dispersion-corrected DFT-functionals reveal that the NT wall-polarization can be increased by nearly a factor of four going from SW-AlSi-Me to DW-AlGe. Absolute vacuum alignment of the NT electronic bands and comparison with those of rutile and anatase TiO2 suggest that the NTs may exhibit marked propensity to both photo-reduction and hole-scavenging. Characterization of the NTs’ band-separation and optical properties reveal the occurrence of (near-)UV inside-outside charge-transfer excitations, which may be effective for electron-hole separation and enhanced photocatalytic activity. Finally, the effects of the NTs’ wall-polarization on the absolute alignment of electron and hole acceptor states of interacting water (H2O) molecules are quantified and discussed.

  18. Electrostatic interactions in finite systems treated with periodic boundary conditions: application to linear-scaling density functional theory.

    Science.gov (United States)

    Hine, Nicholas D M; Dziedzic, Jacek; Haynes, Peter D; Skylaris, Chris-Kriton

    2011-11-28

    We present a comparison of methods for treating the electrostatic interactions of finite, isolated systems within periodic boundary conditions (PBCs), within density functional theory (DFT), with particular emphasis on linear-scaling (LS) DFT. Often, PBCs are not physically realistic but are an unavoidable consequence of the choice of basis set and the efficacy of using Fourier transforms to compute the Hartree potential. In such cases the effects of PBCs on the calculations need to be avoided, so that the results obtained represent the open rather than the periodic boundary. The very large systems encountered in LS-DFT make the demands of the supercell approximation for isolated systems more difficult to manage, and we show cases where the open boundary (infinite cell) result cannot be obtained from extrapolation of calculations from periodic cells of increasing size. We discuss, implement, and test three very different approaches for overcoming or circumventing the effects of PBCs: truncation of the Coulomb interaction combined with padding of the simulation cell, approaches based on the minimum image convention, and the explicit use of open boundary conditions (OBCs). We have implemented these approaches in the ONETEP LS-DFT program and applied them to a range of systems, including a polar nanorod and a protein. We compare their accuracy, complexity, and rate of convergence with simulation cell size. We demonstrate that corrective approaches within PBCs can achieve the OBC result more efficiently and accurately than pure OBC approaches.

  19. Research on ionospheric tomography based on variable pixel height

    Science.gov (United States)

    Zheng, Dunyong; Li, Peiqing; He, Jie; Hu, Wusheng; Li, Chaokui

    2016-05-01

    A novel ionospheric tomography technique based on variable pixel height was developed for the tomographic reconstruction of the ionospheric electron density distribution. The method considers the height of each pixel as an unknown variable, which is retrieved during the inversion process together with the electron density values. In contrast to conventional computerized ionospheric tomography (CIT), which parameterizes the model with a fixed pixel height, the variable-pixel-height computerized ionospheric tomography (VHCIT) model applies a disturbance to the height of each pixel. In comparison with conventional CIT models, the VHCIT technique achieved superior results in a numerical simulation. A careful validation of the reliability and superiority of VHCIT was performed. According to the results of the statistical analysis of the average root mean square errors, the proposed model offers an improvement by 15% compared with conventional CIT models.

  20. Physiological and morphological acclimation to height in cupressoid leaves of 100-year-old Chamaecyparis obtusa.

    Science.gov (United States)

    Shiraki, Ayumi; Azuma, Wakana; Kuroda, Keiko; Ishii, H Roaki

    2016-10-15

    Cupressoid (scale-like) leaves are morphologically and functionally intermediate between stems and leaves. While past studies on height acclimation of cupressoid leaves have focused on acclimation to the vertical light gradient, the relationship between morphology and hydraulic function remains unexplored. Here, we compared physiological and morphological characteristics between treetop and lower-crown leaves of 100-year-old Chamaecyparis obtusa Endl. trees (~27 m tall) to investigate whether height-acclimation compensates for hydraulic constraints. We found that physiological acclimation of leaves was determined by light, which drove the vertical gradient of evaporative demand, while leaf morphology and anatomy were determined by height. Compared with lower-crown leaves, treetop leaves were physiologically acclimated to water stress. Leaf hydraulic conductance was not affected by height, and this contributed to higher photosynthetic rates of treetop leaves. Treetop leaves had higher leaf area density and greater leaf mass per area, which increase light interception but could also decrease hydraulic efficiency. We inferred that transfusion tissue flanking the leaf vein, which was more developed in the treetop leaves, contributes to water-stress acclimation and maintenance of leaf hydraulic conductance by facilitating osmotic adjustment of leaf water potential and efficient water transport from xylem to mesophyll. Our findings may represent anatomical adaptation that compensates for hydraulic constraints on physiological function with increasing height.

  1. Clumping and the Interpretation of kpc-Scale Maps of the Interstellar Medium: Smooth HI and Clumpy, Variable H2 Surface Density

    CERN Document Server

    Leroy, Adam K; Schruba, Andreas; Bolatto, Alberto; Hughes, Annie; Pety, Jerome; Sandstrom, Karin; Schinnerer, Eva; Walter, Fabian

    2013-01-01

    Many recent models consider the structure of individual interstellar medium (ISM) clouds as a way to explain observations of large parts of galaxies. To compare such models to observations, one must understand how to translate between surface densities observed averaging over large (~kpc) scales and surface densities on the scale of individual clouds (~pc scale), which are treated by models. We define a "clumping factor" that captures this translation as the ratio of the mass-weighted surface density, which is often the quantity of physical interest, to the area-weighted surface density, which is observed. We use high spatial resolution (sub-kpc) maps of CO and HI emission from nearby galaxies to measure the clumping factor of both atomic and molecular gas. The molecular and atomic ISM exhibit dramatically different degrees of clumping. As a result, the ratio H2/HI measured at ~kpc resolution cannot be trivially interpreted as a cloud-scale ratio of surface densities. HI emission appears very smooth, with a c...

  2. Spatiotemporal patterns of duck nest density and predation risk: a multi-scale analysis of 18 years and more than 10,000 nests

    Science.gov (United States)

    Ringelman, Kevin M.; Eadie, John M.; Ackerman, Joshua T.; Sih, Andrew; Loughman, Daniel L.; Yarris, Gregory S.; Oldenburger, Shaun L.; McLandress, M. Robert

    2017-01-01

    Many avian species are behaviorally-plastic in selecting nest sites, and may shift to new locations or habitats following an unsuccessful breeding attempt. If there is predictable spatial variation in predation risk, the process of many individuals using prior experience to adaptively change nest sites may scale up to create shifting patterns of nest density at a population level. We used 18 years of waterfowl nesting data to assess whether there were areas of consistently high or low predation risk, and whether low-risk areas increased, and high-risk areas decreased in nest density the following year. We created kernel density maps of successful and unsuccessful nests in consecutive years and found no correlation in predation risk and no evidence for adaptive shifts, although nest density was correlated between years. We also examined between-year correlations in nest density and nest success at three smaller spatial scales: individual nesting fields (10–28 ha), 16-ha grid cells and 4-ha grid cells. Here, results were similar across all scales: we found no evidence for year-to-year correlation in nest success but found strong evidence that nest density was correlated between years, and areas of high nest success increased in nest density the following year. Prior research in this system has demonstrated that areas of high nest density have higher nest success, and taken together, our results suggest that ducks may adaptively select nest sites based on the local density of conspecifics, rather than the physical location of last year's nest. In unpredictable environments, current cues, such as the presence of active conspecific nests, may be especially useful in selecting nest sites. The cues birds use to select breeding locations and successfully avoid predators deserve continued attention, especially in systems of conservation concern.

  3. Inside pyroclastic density currents - uncovering the enigmatic flow structure and transport behaviour in large-scale experiments

    Science.gov (United States)

    Breard, Eric C. P.; Lube, Gert

    2017-01-01

    Pyroclastic density currents (PDCs) are the most lethal threat from volcanoes. While there are two main types of PDCs (fully turbulent, fully dilute pyroclastic surges and more concentrated pyroclastic flows encompassing non-turbulent to turbulent transport) pyroclastic flows, which are the subject of the present study, are far more complex than dilute pyroclastic surges and remain the least understood type despite their far greater hazard, greater runout length and ability to transport vast quantities of material across the Earth's surface. Here we present large-scale experiments of natural volcanic material and gas in order to provide the missing quantitative view of the internal structure and gas-particle transport mechanisms in pyroclastic flows. We show that the outer flow structure with head, body and wake regions broadly resembles current PDC analogues of dilute gravity currents. However, the internal structure, in which lower levels consist of a concentrated granular fluid and upper levels are more dilute, contrasts significantly with the internal structure of fully dilute gravity currents. This bipartite vertical structure shows strong analogy to current conceptual models of high-density turbidity currents, which are responsible for the distribution of coarse sediment in marine basins and of great interest to the hydrocarbon industry. The lower concentrated and non-turbulent levels of the PDC (granular-fluid basal flow) act as a fast-flowing carrier for the more dilute and turbulent upper levels of the current (ash-cloud surge). Strong kinematic coupling between these flow parts reduces viscous dissipation and entrainment of ambient air into the lower part of the ash-cloud surge. This leads to a state of forced super-criticality whereby fast and destructive PDCs can endure even at large distances from volcanoes. Importantly, the basal flow/ash-cloud surge coupling yields a characteristically smooth rheological boundary across the non

  4. Turbulent viscosity and scale laws in turbulent jets with variable density; Viscosite turbulente et lois d`echelles dans les jets turbulents a masse volumique variable

    Energy Technology Data Exchange (ETDEWEB)

    Pietri, L.; Amielh, M.; Anselmet, F.; Fulachier, L. [Institut de Recherche sur les Phinomenes Hors Equilibre Equipe Turbulence, 13 - Marseille (France)

    1997-12-31

    Turbulent flows with strong density variations, like helium jets in the ambient air, have specific properties linked with the difference of gas densities. This paper presents some experimental results of turbulence properties inside such flows: the Reynolds tensions and the associated turbulent viscosity, and some characteristics linked with the statistical properties of the different turbulence scales. These last results allows to show the complexity of such flows characterized by the influence of external parameters (Reynolds number, initial density ratio, initial momentum flux) that govern the evolution of these parameters inside the jet from the nozzle up to regions where similarity properties are reached. (J.S.) 12 refs.

  5. Velocity and density scaling at the outlet of a silo and its role in the expression of the mass flow rate

    Science.gov (United States)

    Maza, D.; Janda, A.; Rubio-Largo, S. M.; Zuriguel, I.; Hidalgo, R. C.

    2013-06-01

    The role of density and velocity profiles in the flow of particles through apertures has been recently put on evidence in a two-dimensional experiment (Phys. Rev. Lett. 108, 248001). For the whole range of apertures studied, both velocity and density profiles are selfsimilar and the obtained scaling functions allow to derive the relevant scales of the problem. Indeed, by means of the functionality obtained for these profiles, an exact expression for the mass flow rate was proposed. Such expression showed a perfect agreement with the experiential data. In this work, we generalize this study to the three dimensional case. We perform numerical simulations of a 3D silo in which the velocity and volume fraction profiles are determined. Both profiles shows that the scaling obtained for 2D can be generalized to the 3D case. Finally, the scaling of the mass flow rate with the outlet radius is discussed.

  6. Assessing biomass based on canopy height profiles using airborne laser scanning data in eucalypt plantations

    Directory of Open Access Journals (Sweden)

    André Gracioso Peres Silva

    2015-12-01

    Full Text Available This study aimed to map the stem biomass of an even-aged eucalyptus plantation in southeastern Brazil based on canopy height profile (CHPs statistics using wall-to-wall discrete return airborne laser scanning (ALS, and compare the results with alternative maps generated by ordinary kriging interpolation from field-derived measurements. The assessment of stem biomass with ALS data was carried out using regression analysis methods. Initially, CHPs were determined to express the distribution of laser point heights in the ALS cloud for each sample plot. The probability density function (pdf used was the Weibull distribution, with two parameters that in a secondary task, were used as explanatory variables to model stem biomass. ALS metrics such as height percentiles, dispersion of heights, and proportion of points were also investigated. A simple linear regression model of stem biomass as a function of the Weibull scale parameter showed high correlation (adj.R2 = 0.89. The alternative model considering the 30th percentile and the Weibull shape parameter slightly improved the quality of the estimation (adj.R2 = 0.93. Stem biomass maps based on the Weibull scale parameter doubled the accuracy of the ordinary kriging approach (relative root mean square error = 6 % and 13 %, respectively.

  7. An analysis of the errors associated with the determination of atmospheric temperature from atmospheric pressure and density data

    Science.gov (United States)

    Minzner, R. A.

    1976-01-01

    A graph was developed for relating delta T/T, the relative uncertainty in atmospheric temperature T, to delta p/p, the relative uncertainty in the atmospheric pressure p, for situations, when T is derived from the slope of the pressure-height profile. A similar graph relates delta T/T to delta roh/rho, the relative uncertainty in the atmospheric density rho, for those cases when T is derived from the downward integration of the density-height profile. A comparison of these two graphs shows that for equal uncertainties in the respective basic parameters, p or rho, smaller uncertainties in the derived temperatures are associated with density-height rather than with pressure-height data. The value of delta T/T is seen to depend not only upon delta p or delta rho, and to a small extent upon the value of T or the related scale height H, but also upon the inverse of delta h, the height increment between successive observations of p or rho. In the case of pressure-height data, delta T/T is dominated by 1/delta h for all values of delta h; for density-height data, delta T/T is dominated by delta rho/rho for delta h smaller than about 5 km. In the case of T derived from density-height data, this inverse relationship between delta T/T and delta h applies only for large values of delta h, that is, for delta h 35 km. No limit exists in the fineness of usable height resolution of T which may be derived from densities, while a fine height resolution in pressure-height data leads to temperature with unacceptably large uncertainties.

  8. The influence of the height of tree,DBH and species diversity of Larix principis-rupprechtii about density%密度对华北落叶松人工林树高、胸径和物种多样性的影响

    Institute of Scientific and Technical Information of China (English)

    张立民; 刘彩虹; 王立辉; 罗晨

    2015-01-01

    以河北省木兰围场国有林场管理局克勒沟林场华北落叶松人工林为研究对象,对标准地内保留密度为400株/hm2、600株/hm2、900株/hm2、1100株/hm2的华北落叶松在上坡位、中坡位、下坡位的树高和胸径以及物种多样性进行了调查分析,结果表明:在保留密度为600株/hm2时,林木生长最好,树高最大;保留密度小于600株/hm2时,树高随着密度的增大而增大,但大于600株/hm2时,树高会随着密度的增大而呈现降低的趋势;胸径会随着保留密度的增大而减小;对不同密度样地中的植物重要值及物种多样性指数进行了计算,林下草本层植物的数量、多样性指数在保留密度为600株/hm2时达到最大值,之后随着密度的增加均呈递减的趋势。%In this paper ,based on the research of L arix p rincipis‐rup p rechtii of Kelegou Forestry Farm of Mulanweichang Forestry Administration ,the tree height and DBH of L ar‐ix p rincipis‐rup p rechtii on uphill ,middlehill ,downhill slope positions ,chosen from suit‐able sample plots in the density of 400 ,600 ,900 ,and 1100 plants/hm 2 were investigated and analyzed .The result showed that in the density of 600 plants/hm 2 ,trees grew the best , with the highest tree height .When in less than 600 plants /hm 2 density ,the tree height in‐creased with the density increasing ,but decreased with the density increasing at more than 600 plants /hm 2 ,with more and more smaller DBH as the density increased .The important value and diversity index of the plants in the sample area under different density was calculat‐ed ,indicating the understory plant herb layer number and diversity index showed a trend of reduceing with the increase of density ,and reached the maximum in the density of 600 plants/hm 2 .

  9. Assessment of hybrid, meta-hybrid-GGA, and long-range corrected density functionals for the estimation of enthalpies of formation, barrier heights, and ionisation potentials of selected C1-C5 oxygenates

    Science.gov (United States)

    El-Nahas, Ahmed M.; Simmie, John M.; Mangood, Ahmed H.; Hirao, Kimihiko; Song, Jong-Won; Watson, Mark A.; Taketsugu, Tetsuya; Koga, Nobuaki

    2015-07-01

    The enthalpies of formation for some selected oxygenates have been calculated by the atomisation energy approach using B3LYP, BHandHLYP, MPW3LYP, MPW1K, MPWB1K, BB1K, MPW1B95, BMK, and long-range corrected (LC-ωPBE, LC-BOP, LCgau-BOP, LC-BOP12, LCgau-B97) density functionals, as well as the composite CBS-QB3 method. Compared with experiment, BMK, LC-ωPBE, LCgau-BOP, LC-BOP12, LCgau-B97, MPW195, MPW3LYP functionals and CBS-QB3 give root mean square errors (RMSE) in enthalpies of formation no greater than 4 kcal/mol, whilst MPW1K and BHandHLYP show much worse performance (RMSE of 20-40 kcal/mol). The B3LYP, MPWB1K, and BB1K results fall between the two extremes. Energy barriers for the dominant paths in the unimolecular decomposition of simple esters (HCO2CH3, C2H5CO2C2H5), C1-C3 acids, and 1-butanol are reproduced well by CBS-QB3, BMK, BB1K, LCgau-B97, and PW1B95 (RMSE = 1-2 kcal/mol), while other LC methods (LC-ωPBE, LC-BOP, LCgau-BOP, and LC-BOP12) show a deviation of up to 4 kcal/mol. For the ionisation potentials, calculated from Koopman's theorem, all of the investigated LC-methods give good results compared with other density functional theory functionals with a maximum deviation of 0.4 eV, except for LCgau-B97, which has an RMSE of 0.7 eV.

  10. A new global model for the ionospheric F2 peak height for radio wave propagation

    Directory of Open Access Journals (Sweden)

    M. M. Hoque

    2012-05-01

    Full Text Available The F2-layer peak density height hmF2 is one of the most important ionospheric parameters characterizing HF propagation conditions. Therefore, the ability to model and predict the spatial and temporal variations of the peak electron density height is of great use for both ionospheric research and radio frequency planning and operation. For global hmF2 modelling we present a nonlinear model approach with 13 model coefficients and a few empirically fixed parameters. The model approach describes the temporal and spatial dependencies of hmF2 on global scale. For determining the 13 model coefficients, we apply this model approach to a large quantity of global hmF2 observational data obtained from GNSS radio occultation measurements onboard CHAMP, GRACE and COSMIC satellites and data from 69 worldwide ionosonde stations. We have found that the model fits to these input data with the same root mean squared (RMS and standard deviations of 10%. In comparison with the electron density NeQuick model, the proposed Neustrelitz global hmF2 model (Neustrelitz Peak Height Model – NPHM shows percentage RMS deviations of about 13% and 12% from the observational data during high and low solar activity conditions, respectively, whereas the corresponding deviations for the NeQuick model are found 18% and 16%, respectively.

  11. The response of short-scale density fluctuations to the activity of beta-induced Alfvén eigenmodes during strong tearing modes on EAST tokamak

    Science.gov (United States)

    Cao, G. M.; Li, Y. D.; Li, Q.; Sun, P. J.; Wu, G. J.; Hu, L. Q.; the EAST Team

    2015-08-01

    Beta-induced Alfvén eigenmodes (BAEs) during strong tearing modes (TMs) have been frequently observed in fast-electron plasmas of EAST tokamak. The dynamics of the short-scale ({k}\\perp {ρ }s~{1.5-4.3}) density fluctuations during the activity of BAEs with strong TMs has been preliminarily investigated by a tangential CO2 laser collective scattering system. The results suggest the active, but different, response of short-scale density fluctuations to the TMs and BAEs. In the low-frequency (0-10 kHz) part of density fluctuations, there are harmonic oscillations totally corresponding to those of TMs. In the medium-high frequency (10-250 kHz) part of density fluctuations, with the appearance of the BAEs, the medium-high frequency density fluctuations begin to be dominated by several quasi-coherent (QC) modes, and the frequencies of the QC modes seem to be related to the changes of both TMs and BAEs. These results would shed some light on the understanding of the multi-scale interaction physics.

  12. Influence of geographical scale on the detection of density dependence in the host-parasite system, Arvicola terrestris and Taenia taeniaeformis.

    Science.gov (United States)

    Deter, J; Berthier, K; Chaval, Y; Cosson, J F; Morand, S; Charbonnel, N

    2006-04-01

    Infection by the cestode Taenia taeniaeformis was investigated within numerous cyclic populations of the fossorial water vole Arvicola terrestris sampled during 4 years in Franche-Comté (France). The relative influence of different rodent demographic parameters on the presence of this cestode was assessed by considering (1) the demographic phase of the cycle; (2) density at the local geographical scale (10 km2). The local scale corresponded to the rodent population (intermediate host), while the large scale corresponded to the definitive host population (wild and feral cats). General linear models based on analyses of 1804 voles revealed the importance of local density but also of year, rodent age, season and interactions between year and season and between age and season. Prevalence was significantly higher in low vole densities than during local outbreaks. By contrast, the large geographical scale density and the demographic phase had less influence on infection by the cestode. The potential impacts of the cestode on the fitness of the host were assessed and infection had no effect on the host body mass, litter size or sexual activity of voles.

  13. Ice-shelf height variability in Amundsen Sea linked to ENSO

    Science.gov (United States)

    Paolo, Fernando; Fricker, Helen; Padman, Laurie

    2016-04-01

    Atmospheric and sea-ice conditions around Antarctica, particularly in the Amundsen and Bellingshausen seas, respond to climate dynamics in the tropical Pacific Ocean on interannual time scales including the El Nino-Southern Oscillation (ENSO). It has been hypothesized that the mass balance of the Antarctic Ice Sheet, including its floating ice shelves, also responds to this climate signal; however, this has not yet been unambiguously demonstrated. We apply multivariate singular spectrum analysis (MSSA) to 18-year (1994-2012) time series of ice-shelf height derived from satellite radar altimetry in the Amundsen Sea (AS) region. This advanced spectral method distinguishes between regular deterministic behavior ("cycles") at sub-decadal time scale and irregular behavior ("noise") at shorter time scales. Although the long-term trends in ice-shelf height change are much larger than the range of interannual variability in the AS region, the short-term rate of change dh/dt can vary about the trend by more than 50%. We extract the principal modes of variability (EOFs) based on common spectral properties from a set of 140 height time series. The mode of interannual variability in the AS ice-shelf height is strongly correlated with the low-frequency mode of ENSO (periodicity of ~4.5 years) as represented by the Southern Oscillation Index. This interannual mode in ice-shelf height, represented by the two leading EOFs, is responsible for about 25% of the variance in the de-trended data set. The ice-shelf height in the AS is expected to respond to changes in precipitation and inflows of warm subsurface Circumpolar Deep Water (CDW) into the ocean cavities under the ice shelves, altering basal melt rates. While we find a correlation between modeled precipitation anomalies and ice-shelf height, we are investigating (a) errors in model precipitation, (b) radar backscatter and firn-density issues, and (c) ocean contribution correlated with atmosphere through wind-stress forcing. We

  14. Electric Field and Plasma Density Observations of Large Scale (100's of km) Waves Below the Equatorial F-peak as Seeds of Spread-F

    Science.gov (United States)

    Pfaff, R. F.; Freudenreich, H.; Klenzing, J.; Liebrecht, C.

    2012-12-01

    Electric field and plasma density observations gathered on the C/NOFS satellite are presented in cases where the ionosphere F-peak has been elevated above the satellite perigee of 400 km in the evening. During these passes, data from the electric field and plasma density probes on the satellite frequently show evidence for 400-500km-scale bottomside "undulations" that appear in the density and electric field data. In one case, these large scale waves are associated with a strong shear in the zonal E x B flow, as evidenced by variations in the meridional (outward) electric fields observed above and below the F-peak. These undulations are devoid of smaller scale structures in the early evening, yet appear at later local times along the same orbit associated with fully-developed spread-F with smaller scale structures. This suggests that they may be precursor waves for spread-F, driven by a collisional shear instability, following ideas advanced previously by researchers using data from the Jicamarca radar. We present statistics of numerous examples of these large scale waves detected by instruments on the C/NOFS satellite.

  15. Accurate barrier heights using diffusion Monte Carlo

    CERN Document Server

    Krongchon, Kittithat; Wagner, Lucas K

    2016-01-01

    Fixed node diffusion Monte Carlo (DMC) has been performed on a test set of forward and reverse barrier heights for 19 non-hydrogen-transfer reactions, and the nodal error has been assessed. The DMC results are robust to changes in the nodal surface, as assessed by using different mean-field techniques to generate single determinant wave functions. Using these single determinant nodal surfaces, DMC results in errors of 1.5(5) kcal/mol on barrier heights. Using the large data set of DMC energies, we attempted to find good descriptors of the fixed node error. It does not correlate with a number of descriptors including change in density, but does correlate with the gap between the highest occupied and lowest unoccupied orbital energies in the mean-field calculation.

  16. The large-scale structure of the halo of the Andromeda galaxy. I. Global stellar density, morphology and metallicity properties

    Energy Technology Data Exchange (ETDEWEB)

    Ibata, Rodrigo A.; Martin, Nicolas F. [Observatoire astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de lUniversité, F-67000 Strasbourg (France); Lewis, Geraint F. [Institute of Astronomy, School of Physics A28, University of Sydney, NSW 2006 (Australia); McConnachie, Alan W. [NRC Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC, V9E 2E7 (Canada); Irwin, Michael J. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Ferguson, Annette M. N.; Bernard, Edouard J.; Peñarrubia, Jorge [Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Babul, Arif; Navarro, Julio [Department of Physics and Astronomy, University of Victoria, 3800 Finnerty Road, Victoria, British Columbia V8P 5C2 (Canada); Chapman, Scott C. [Department of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Road, Halifax NS B3H 4R2 (Canada); Collins, Michelle [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Fardal, Mark [University of Massachusetts, Department of Astronomy, LGRT 619-E, 710 North Pleasant Street, Amherst, MA 01003-9305 (United States); Mackey, A. D. [RSAA, The Australian National University, Mount Stromlo Observatory, Cotter Road, Weston Creek ACT 2611 (Australia); Rich, R. Michael [Department of Physics and Astronomy, University of California, Los Angeles, PAB, 430 Portola Plaza, Los Angeles, CA 90095-1547 (United States); Tanvir, Nial [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Widrow, Lawrence, E-mail: rodrigo.ibata@astro.unistra.fr [Department of Physics, Engineering Physics, and Astronomy Queen' s University, Kingston, Ontario K7L 3N6 (Canada)

    2014-01-10

    We present an analysis of the large-scale structure of the halo of the Andromeda galaxy, based on the Pan-Andromeda Archeological Survey (PAndAS), currently the most complete map of resolved stellar populations in any galactic halo. Despite the presence of copious substructures, the global halo populations follow closely power-law profiles that become steeper with increasing metallicity. We divide the sample into stream-like populations and a smooth halo component (defined as the population that cannot be resolved into spatially distinct substructures with PAndAS). Fitting a three-dimensional halo model reveals that the most metal-poor populations ([Fe/H]<−1.7) are distributed approximately spherically (slightly prolate with ellipticity c/a = 1.09 ± 0.03), with only a relatively small fraction residing in discernible stream-like structures (f {sub stream} = 42%). The sphericity of the ancient smooth component strongly hints that the dark matter halo is also approximately spherical. More metal-rich populations contain higher fractions of stars in streams, with f {sub stream} becoming as high as 86% for [Fe/H]>−0.6. The space density of the smooth metal-poor component has a global power-law slope of γ = –3.08 ± 0.07, and a non-parametric fit shows that the slope remains nearly constant from 30 kpc to ∼300 kpc. The total stellar mass in the halo at distances beyond 2° is ∼1.1 × 10{sup 10} M {sub ☉}, while that of the smooth component is ∼3 × 10{sup 9} M {sub ☉}. Extrapolating into the inner galaxy, the total stellar mass of the smooth halo is plausibly ∼8 × 10{sup 9} M {sub ☉}. We detect a substantial metallicity gradient, which declines from ([Fe/H]) = –0.7 at R = 30 kpc to ([Fe/H]) = –1.5 at R = 150 kpc for the full sample, with the smooth halo being ∼0.2 dex more metal poor than the full sample at each radius. While qualitatively in line with expectations from cosmological simulations, these observations are of great importance as

  17. Large-scale all-electron density functional theory calculations using an enriched finite-element basis

    Science.gov (United States)

    Kanungo, Bikash; Gavini, Vikram

    2017-01-01

    We present a computationally efficient approach to perform large-scale all-electron density functional theory calculations by enriching the classical finite element basis with compactly supported atom-centered numerical basis functions that are constructed from the solution of the Kohn-Sham (KS) problem for single atoms. We term these numerical basis functions as enrichment functions, and the resultant basis as the enriched finite element basis. The compact support for the enrichment functions is obtained by using smooth cutoff functions, which enhances the conditioning and maintains the locality of the enriched finite element basis. The integrals involved in the evaluation of the discrete KS Hamiltonian and overlap matrix in the enriched finite element basis are computed using an adaptive quadrature grid that is constructed based on the characteristics of enrichment functions. Further, we propose an efficient scheme to invert the overlap matrix by using a blockwise matrix inversion in conjunction with special reduced-order quadrature rules, which is required to transform the discrete Kohn-Sham problem to a standard eigenvalue problem. Finally, we solve the resulting standard eigenvalue problem, in each self-consistent field iteration, by using a Chebyshev polynomial based filtering technique to compute the relevant eigenspectrum. We demonstrate the accuracy, efficiency, and parallel scalability of the proposed method on semiconducting and heavy-metallic systems of various sizes, with the largest system containing 8694 electrons. We obtain accuracies in the ground-state energies that are ˜1 mHa with reference ground-state energies employing classical finite element as well as Gaussian basis sets. Using the proposed formulation based on enriched finite element basis, for accuracies commensurate with chemical accuracy, we observe a staggering 50 -300 -fold reduction in the overall computational time when compared to classical finite element basis. Further, we find a

  18. Height and Tilt Geometric Texture

    DEFF Research Database (Denmark)

    Andersen, Vedrana; Desbrun, Mathieu; Bærentzen, Jakob Andreas

    2009-01-01

    We propose a new intrinsic representation of geometric texture over triangle meshes. Our approach extends the conventional height field texture representation by incorporating displacements in the tangential plane in the form of a normal tilt. This texture representation offers a good practical...... compromise between functionality and simplicity: it can efficiently handle and process geometric texture too complex to be represented as a height field, without having recourse to full blown mesh editing algorithms. The height-and-tilt representation proposed here is fully intrinsic to the mesh, making...

  19. Efficient linear-scaling calculation of response properties: density matrix-based Laplace-transformed coupled-perturbed self-consistent field theory.

    Science.gov (United States)

    Beer, Matthias; Ochsenfeld, Christian

    2008-06-14

    A density matrix-based Laplace reformulation of coupled-perturbed self-consistent field (CPSCF) theory is presented. It allows a direct, instead of iterative, solution for the integral-independent part of the density matrix-based CPSCF (D-CPSCF) equations [J. Kussmann and C. Ochsenfeld, J. Chem. Phys. 127, 054103 (2007)]. In this way, the matrix-multiplication overhead compared to molecular orbital-based solutions is reduced to a minimum, while at the same time, the linear-scaling behavior of D-CPSCF theory is preserved. The present Laplace-based equation solver is expected to be of general applicability.

  20. Alaska Geoid Heights (GEOID96)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This 2' x 4' geoid height grid for Alaska is distributed as a GEOID96 model. The computation used 1.1 million terrestrial and marine gravity data held in the...

  1. Mexico Geoid Heights (MEXICO97)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This 2' geoid height grid for Mexico, and North-Central America, is the MEXICO97 geoid model. The computation used about one million terrestrial and marine gravity...

  2. The large-scale correlations of multi-cell densities and profiles, implications for cosmic variance estimates

    CERN Document Server

    Codis, Sandrine; Pichon, Christophe

    2016-01-01

    In order to quantify the error budget in the measured probability distribution functions of cell densities, the two-point statistics of cosmic densities in concentric spheres is investigated. Bias functions are introduced as the ratio of their two-point correlation function to the two-point correlation of the underlying dark matter distribution. They describe how cell densities are spatially correlated. They are computed here via the so-called large deviation principle in the quasi-linear regime. Their large-separation limit is presented and successfully compared to simulations for density and density slopes: this regime is shown to be rapidly reached allowing to get sub-percent precision for a wide range of densities and variances. The corresponding asymptotic limit provides an estimate of the cosmic variance of standard concentric cell statistics applied to finite surveys. More generally, no assumption on the separation is required for some specific moments of the two-point statistics, for instance when pre...

  3. Height Determination Techniques for the Next National Height System of Finland- A Case Study

    Science.gov (United States)

    Saari, T.; Saaranen, V.; Kaartinen, H.; Poutanen, M.; Kukko, A.; Nyberg, S.

    2014-11-01

    Precise levelling is known for its accuracy and reliability in height determination, but the process itself is slow, laborious and expensive. FGI has started a project to develop methods for height determination that could decrease the creation time of national height systems without losing the required accuracy. In this pilot project, we studied precise levelling and alternative techniques: MLS (Mobile Laser Scanning) and GNSS (Global Navigation Satellite System) levelling, which included static GPS (Global Positioning System) and VRS (Virtual Reference Station) measurements.We compared the techniques in a field test, where the height difference of two known benchmarks were measured. All of the height differences were within 16 mm from each other, where the results from the precise levelling and the GPS levelling differed from 0.5-1.0 mm. Results from the MLS measurements were more than 5.0 mm off from the others and the average of the VRS measurements was 10.0 mm off. The uncertainties are compatible with the results, since the largest RMS values were calculated from the MLS and the VRS measurements.This research highlighted the differences of the techniques, but none of them is yet to be abandoned. The study should be expanded into a larger scale to better evaluate strengths and weaknesses of the techniques.

  4. Comparison of Conjugate Gradient Density Matrix Search and Chebyshev Expansion Methods for Avoiding Diagonalization in Large-Scale Electronic Structure Calculations

    Science.gov (United States)

    Bates, Kevin R.; Daniels, Andrew D.; Scuseria, Gustavo E.

    1998-01-01

    We report a comparison of two linear-scaling methods which avoid the diagonalization bottleneck of traditional electronic structure algorithms. The Chebyshev expansion method (CEM) is implemented for carbon tight-binding calculations of large systems and its memory and timing requirements compared to those of our previously implemented conjugate gradient density matrix search (CG-DMS). Benchmark calculations are carried out on icosahedral fullerenes from C60 to C8640 and the linear scaling memory and CPU requirements of the CEM demonstrated. We show that the CPU requisites of the CEM and CG-DMS are similar for calculations with comparable accuracy.

  5. Simulation of sludge blanket height in clarifiers

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhen; WU Zhi-chao; WANG Zhi-wei; GU Guo-wei

    2009-01-01

    Sludge blanket height (SBH) is an important parameter in the clarifier design,operation and control.Based on an overview and classification of SBH algorithms,a modifed SBH algorithm is proposed by incorporating a threshold concentration limit into a relative concentration sharp change algorithm to eliminate the disturbance of compression interfaces on the correct simulation of SBH.Pilot-scale test data are adopted to compare reliability of three SBH algorithms reported in literature and the modified SBH algorithm developed in this paper.Calculated results demonstrate that the three SBH algorithms give results with large deviation (>50%) from measured SBH,especially under low solid flux conditions.The modified algorithm is computationally efficient and reliable in matching the measured data.It is incorporated into a onedimensional clarifier model for stable simulation of pilot-scale experimental clarifier data and into dynamic simulation of a full-scale wastewater treatment plant (WWTP) clarifier data.

  6. Perching behaviour and perch height preference of laying hens in furnished cages varying in height.

    Science.gov (United States)

    Struelens, E; Tuyttens, F A M; Duchateau, L; Leroy, T; Cox, M; Vranken, E; Buyse, J; Zoons, J; Berckmans, D; Odberg, F; Sonck, B

    2008-07-01

    1. The objective was to investigate the effect of cage height on perch height preference and perching behaviour in laying hens. Twelve groups of two hens and 12 groups of 14 hens were tested in furnished cages equipped with two wooden perches. These stepwise perches were designed such that hens could choose between 7 different heights (6, 11, 16, 21, 26, 31 and 36 cm). Day- and night-time perching behaviour was observed on 4 consecutive days with a different cage height each day: 150, 55, 50 and 45 cm. 2. Given that a minimum perch-roof distance of 19 to 24 cm was available, hens preferred to roost on the highest perches at night. 3. Lowering cage height not only forced hens to use lower perches, but also reduced time spent on the perches during the day (two-hen and 14-hen test) and night (14-hen test). Moreover, it affected daytime behavioural activities (more standing and less preening) on the perches in the two-hen tests (but not in the 14-hen tests). 4. During the day lower perches were used more for standing and walking, higher perches more for sitting and sleeping. This behavioural differentiation was most pronounced in the highest cages. 5. Perch preference and perching behaviour depend on both the floor-perch distance and the perch-roof distance. Higher cages provide more opportunity for higher perches (which hens prefer), for better three-dimensional spacing (and consequently reduced density at floor level) and for behavioural differentiation according to perch height.

  7. Glacial effects limiting mountain height.

    Science.gov (United States)

    Egholm, D L; Nielsen, S B; Pedersen, V K; Lesemann, J-E

    2009-08-13

    The height of mountain ranges reflects the balance between tectonic rock uplift, crustal strength and surface denudation. Tectonic deformation and surface denudation are interdependent, however, and feedback mechanisms-in particular, the potential link to climate-are subjects of intense debate. Spatial variations in fluvial denudation rate caused by precipitation gradients are known to provide first-order controls on mountain range width, crustal deformation rates and rock uplift. Moreover, limits to crustal strength are thought to constrain the maximum elevation of large continental plateaus, such as those in Tibet and the central Andes. There are indications that the general height of mountain ranges is also directly influenced by the extent of glaciation through an efficient denudation mechanism known as the glacial buzzsaw. Here we use a global analysis of topography and show that variations in maximum mountain height correlate closely with climate-controlled gradients in snowline altitude for many high mountain ranges across orogenic ages and tectonic styles. With the aid of a numerical model, we further demonstrate how a combination of erosional destruction of topography above the snowline by glacier-sliding and commensurate isostatic landscape uplift caused by erosional unloading can explain observations of maximum mountain height by driving elevations towards an altitude window just below the snowline. The model thereby self-consistently produces the hypsometric signature of the glacial buzzsaw, and suggests that differences in the height of mountain ranges mainly reflect variations in local climate rather than tectonic forces.

  8. Encounter Probability of Significant Wave Height

    DEFF Research Database (Denmark)

    Liu, Z.; Burcharth, H. F.

    The determination of the design wave height (often given as the significant wave height) is usually based on statistical analysis of long-term extreme wave height measurement or hindcast. The result of such extreme wave height analysis is often given as the design wave height corresponding to a c...

  9. Correlation techniques and measurements of wave-height statistics

    Science.gov (United States)

    Guthart, H.; Taylor, W. C.; Graf, K. A.; Douglas, D. G.

    1972-01-01

    Statistical measurements of wave height fluctuations have been made in a wind wave tank. The power spectral density function of temporal wave height fluctuations evidenced second-harmonic components and an f to the minus 5th power law decay beyond the second harmonic. The observations of second harmonic effects agreed very well with a theoretical prediction. From the wave statistics, surface drift currents were inferred and compared to experimental measurements with satisfactory agreement. Measurements were made of the two dimensional correlation coefficient at 15 deg increments in angle with respect to the wind vector. An estimate of the two-dimensional spatial power spectral density function was also made.

  10. Boundary layer heights derived from velocity spectra

    Energy Technology Data Exchange (ETDEWEB)

    Hoejstrup, J.; Barthelmie, R.J. [Risoe National Lab., Roskilde (Denmark); Kaellstrand, B. [Univ. of Uppsala, Uppsala (Sweden)

    1997-10-01

    It is a well-known fact that the height of the mixed layer determines the size of the largest and most energetic eddies that can be observed in the unstable boundary layer, and consequently a peak can be observed in the power spectra of the along-wind velocity component at scales comparable to the mixed layer depth. We will now show how the mixed layer depth can be derived from the u-specta and the results will be compared with direct measurements using pibal and tethersonde measurements. (au)

  11. An analysis of the relationship between bodily injury severity and fall height in victims of fatal falls from height

    Directory of Open Access Journals (Sweden)

    Grzegorz Teresiński

    2017-03-01

    Full Text Available Aim of the study : One of the basic issues discussed in forensic literature regarding falls from a height is determination of fall heights and differentiation between suicidal and accidental falls. The aim of the study was to verify the usefulness of the available methods for the purposes of forensic expertises. Material and methods : The study encompassed fatalities of falls from a height whose autopsies were performed in the Department of Forensic Medicine in Lublin. Results : Similarly to other authors, the severity of injuries was assessed using the Abbreviated Injury Scale (AIS and injury severity score (ISS. The study findings demonstrated a statistically significant correlation between the fall height and the severity of injuries according to ISS and a statistically significant difference in fall heights between the groups of accidents and suicides.

  12. Gravity and Height Variations at Medicina, Italy

    Science.gov (United States)

    Bruni, Sara; Zerbini, Susanna; Errico, Maddalena; Santi, Efisio; Wziontek, Hartmut

    2017-04-01

    Since 1996, at the Medicina station, height and gravity variations are monitored continuously by means of GPS, VLBI and superconducting gravimeter (SG) data. Additionally, absolute gravity observations are performed twice a year and environmental parameters, among others water table levels, are regularly acquired. Levelling between the different monuments at the site area is also carried out repeatedly to constrain local ties in the vertical position. Two GPS systems are located very close to each other, and both are in close proximity to the VLBI antenna. Twenty years of data are now available, which allow investigating both long- and short-period height and gravity signals together with their relevant correlations. Natural land subsidence, which is well known to occur in the area, is a major component of the observed long-term behavior; however, non-linear long-period signatures are also present in the time series. On a shorter time scale, fingerprints of the water table seasonal oscillations can be recognized in the data. The Medicina site is characterized by clayey soil subjected to consolidation effects when the water table lowers during summer periods. The pillar on which the SG is installed is especially affected because of its shallow foundation, causing height decreases in the order of 2.5-3 cm for water table lowering of 2 m. This study presents a comparative analysis of the different data sets with the aim of separating mass and deformation contributions in the SG gravity record.

  13. Height and Breast Cancer Risk

    DEFF Research Database (Denmark)

    Zhang, Ben; Shu, Xiao-Ou; Delahanty, Ryan J

    2015-01-01

    BACKGROUND: Epidemiological studies have linked adult height with breast cancer risk in women. However, the magnitude of the association, particularly by subtypes of breast cancer, has not been established. Furthermore, the mechanisms of the association remain unclear. METHODS: We performed a meta......-analysis to investigate associations between height and breast cancer risk using data from 159 prospective cohorts totaling 5216302 women, including 113178 events. In a consortium with individual-level data from 46325 case patients and 42482 control patients, we conducted a Mendelian randomization analysis using...... a genetic score that comprised 168 height-associated variants as an instrument. This association was further evaluated in a second consortium using summary statistics data from 16003 case patients and 41335 control patients. RESULTS: The pooled relative risk of breast cancer was 1.17 (95% confidence...

  14. replacing orthometric heights with ellipsoidal heights in engineering ...

    African Journals Online (AJOL)

    user

    This work investigates the use of ellipsoidal heights in place of orthometric ... be represented mathematically, and therefore enables computation to be .... suitable locations along the levelling routes. The ..... 5.3 Assumptions and theoretical approximations made ... tectonics movement, deformation and land subsidence.

  15. Tree Height Calculator: An Android App for Estimating Tree Height

    Science.gov (United States)

    Burca, V. S.; Htet, N. M.; Huang, X.; de Lanerolle, T. R.; Morelli, R.; Gourley, J. R.

    2011-12-01

    Conventionally, measuring tree height requires a collection of different tools - clinometer, transit, pencil, paper, laptop computer. Results are recorded manually and entered into a spreadsheet or database for future calculation and analysis. Tree Height Calculator is a mobile Android app the integrates the various steps in this process thereby improving the accuracy and dramatically reducing the time required to go from taking measurements to analyzing data. Given the user's height and the distance from the base of the tree (which can be downloaded into the app from a server), the app uses the phone's orientation sensor to calculate the angle of elevation. A simple trigonometric formula is then used to calculate and record the tree's height in the phone's database. When the phone has a WiFi connection, the data are transmitted to a server, from where they can be downloaded directly into a spreadsheet. The application was first tested in an Environmental Science laboratory at Trinity College. On the first trial, 103 data samples were collected, stored, and uploaded to the online database with only couple of dropped data points. On the second trial, 98 data samples were gathered with no loss of data. The app combined the individual measurements taken by the students in the lab, reducing the time required to produce a graph of the class's results from days to hours.

  16. A reduced-scaling density matrix-based method for the computation of the vibrational Hessian matrix at the self-consistent field level

    Energy Technology Data Exchange (ETDEWEB)

    Kussmann, Jörg; Luenser, Arne; Beer, Matthias; Ochsenfeld, Christian, E-mail: christian.ochsenfeld@uni-muenchen.de [Chair of Theoretical Chemistry, Department of Chemistry, University of Munich (LMU), Butenandtstr. 7, D-81377 München (Germany)

    2015-03-07

    An analytical method to calculate the molecular vibrational Hessian matrix at the self-consistent field level is presented. By analysis of the multipole expansions of the relevant derivatives of Coulomb-type two-electron integral contractions, we show that the effect of the perturbation on the electronic structure due to the displacement of nuclei decays at least as r{sup −2} instead of r{sup −1}. The perturbation is asymptotically local, and the computation of the Hessian matrix can, in principle, be performed with O(N) complexity. Our implementation exhibits linear scaling in all time-determining steps, with some rapid but quadratic-complexity steps remaining. Sample calculations illustrate linear or near-linear scaling in the construction of the complete nuclear Hessian matrix for sparse systems. For more demanding systems, scaling is still considerably sub-quadratic to quadratic, depending on the density of the underlying electronic structure.

  17. Absolute OH and O radical densities in effluent of a He/H2O micro-scaled atmospheric pressure plasma jet

    Science.gov (United States)

    Benedikt, J.; Schröder, D.; Schneider, S.; Willems, G.; Pajdarová, A.; Vlček, J.; Schulz-von der Gathen, V.

    2016-08-01

    The effluent of a micro-scaled atmospheric pressure plasma jet (μ-APPJ) operated in helium with admixtures of water vapor (≲ {{10}4} ppm) has been analyzed by means of cavity ring-down laser absorption spectroscopy and molecular beam mass spectrometry to measure hydroxyl (OH) radical densities, and by two-photon absorption laser-induced fluorescence spectroscopy to measure atomic oxygen (O) densities. Additionally, the performance of the bubbler as a source of water vapor in the helium feed gas has been carefully characterized and calibrated. The largest OH and O densities in the effluent of 2× {{10}14}~\\text{c}{{\\text{m}}-3} and 3.2× {{10}13}~\\text{c}{{\\text{m}}-3} , respectively, have been measured at around 6000 ppm. The highest selectivity is reached around 1500 ppm, where the OH density is at  ∼63% of its maximum value and is 14 times larger than the O density. The measured density profiles and distance variations are compared to the results of a 2D axially symmetric fluid model of species transport and reaction kinetics in the plasma effluent. It is shown that the main loss of OH radicals in the effluent is their mutual reaction. In the case of O, reactions with other species than OH also have to be considered to explain the density decay in the effluent. The results presented here provide additional information for understanding the plasma-chemical processes in non-equilibrium atmospheric pressure plasmas. They also open the way to applying μ-APPJ with He/H2O as a selective source of OH radicals.

  18. Determination of plant height for weed detection in stereoscopic images

    OpenAIRE

    Piron, Alexis; Leemans, Vincent; Kleynen, Olivier; Destain, Marie-France

    2008-01-01

    The aim of this study was twofold. The first goal was to acquire high accuracy stereoscopic images of small-scale field scenes, the second to examine the potential of plant height as a discriminant factor between crop and weed, within carrot rows. Emphasis was put on how to determine actual plant height taking into account the variable distance from camera to ground and ground irregularities for in-field measurements. Multispectral stereoscopic images were taken over a period o...

  19. Fear of heights in infants?

    Science.gov (United States)

    Adolph, Karen E; Kretch, Kari S; LoBue, Vanessa

    2014-02-01

    Based largely on the famous "visual cliff" paradigm, conventional wisdom is that crawling infants avoid crossing the brink of a dangerous drop-off because they are afraid of heights. However, recent research suggests that the conventional wisdom is wrong. Avoidance and fear are conflated, and there is no compelling evidence to support fear of heights in human infants. Infants avoid crawling or walking over an impossibly high drop-off because they perceive affordances for locomotion-the relations between their own bodies and skills and the relevant properties of the environment that make an action such as descent possible or impossible.

  20. Socioeconomic development and secular trend in height in China.

    Science.gov (United States)

    Zong, Xin-Nan; Li, Hui; Wu, Hua-Hong; Zhang, Ya-Qin

    2015-12-01

    The objective of this study was to examine the effect of socioeconomic development on secular trend in height among children and adolescents in China. Body height and spermarcheal/menarcheal ages were obtained from two periodic large-scale national representative surveys in China between 1975 and 2010. Chinese socioeconomic development indicators were obtained from the United Nations world population prospects. The effects of plausible determinants were assessed by partial least-squares regression. The average height of children and adolescents improved in tandem with socioeconomic development, without any tendency to plateau. The increment of height trend presented larger around puberty than earlier or later ages. The partial least-squares regressions with gross national income, life expectancy and spermarcheal/menarcheal age accounted for increment of height trend from 88.3% to 98.3% for males and from 82.9% to 97.3% for females in adolescence. Further, through the analysis of the variable importance for projection, the contributions of gross national income and life expectancy on height increment were confirmed to be significant in childhood and adolescence, and the contribution of spermarcheal/menarcheal age was superior to both of them in adolescence. We concluded that positive secular trend in height in China was significantly associated with socioeconomic status (GNI as indicator) and medical and health conditions (life expectancy as indicator). Earlier onset of spermarche and menarche proved to be an important role in larger increment of the trend over time of height at puberty for a population.

  1. Measuring perceived ceiling height in a visual comparison task.

    Science.gov (United States)

    von Castell, Christoph; Hecht, Heiko; Oberfeld, Daniel

    2017-03-01

    When judging interior space, a dark ceiling is judged to be lower than a light ceiling. The method of metric judgments (e.g., on a centimetre scale) that has typically been used in such tasks may reflect a genuine perceptual effect or it may reflect a cognitively mediated impression. We employed a height-matching method in which perceived ceiling height had to be matched with an adjustable pillar, thus obtaining psychometric functions that allowed for an estimation of the point of subjective equality (PSE) and the difference limen (DL). The height-matching method developed in this paper allows for a direct visual match and does not require metric judgment. It has the added advantage of providing superior precision. Experiment 1 used ceiling heights between 2.90 m and 3.00 m. The PSE proved sensitive to slight changes in perceived ceiling height. The DL was about 3% of the physical ceiling height. Experiment 2 found similar results for lower (2.30 m to 2.50 m) and higher (3.30 m to 3.50 m) ceilings. In Experiment 3, we additionally varied ceiling lightness (light grey vs. dark grey). The height matches showed that the light ceiling appeared significantly higher than the darker ceiling. We therefore attribute the influence of ceiling lightness on perceived ceiling height to a direct perceptual rather than a cognitive effect.

  2. Down on heights? One in three has visual height intolerance.

    Science.gov (United States)

    Huppert, Doreen; Grill, Eva; Brandt, Thomas

    2013-02-01

    The distressing phenomenon of visual height intolerance (vHI) occurs when a visual stimulus causes apprehension of losing control of balance and falling from some height. Epidemiological data of this condition in the general population are lacking. Assignment of prevalence, determinants, and compensation of vHI was performed in a cross-sectional epidemiological study of 3,517 individuals representing the German population. Life-time prevalence of vHI is 28 % (females 32 %). A higher prevalence is associated independently with a family history of vHI, anxiety disorders, migraine, or motion sickness susceptibility. Women aged 50-59 have a higher prevalence than younger women or men of all ages. Initial attacks occur most often (30 %) in the second decade; however, attacks can manifest throughout life. The main symptoms are fearfulness, inner agitation, a queasy-stomach feeling, subjective postural instability with to-and-fro vertigo, and weakness in the knees. Climbing a tower is the first most common precipitating stimulus; the spectrum of such stimuli widens with time in more than 50 % of afflicted individuals. The most frequent reaction to vHI is to avoid the triggering stimuli (>50 %); 11 % of susceptible individuals consult a doctor, most often a general practitioner, neurologist, ENT doctor, or psychiatrist. In brief, visual height intolerance affects one-third of the general population, considerably restricting the majority of these individuals in their daily activities. The data show that the two terms do not indicate a categorical distinction but rather a continuum from slight forms of visual height intolerance to the specific phobia of fear of heights.

  3. Dynamic modelling of high biomass density cultivation and biohydrogen production in different scales of flat plate photobioreactors.

    Science.gov (United States)

    Zhang, Dongda; Dechatiwongse, Pongsathorn; Del Rio-Chanona, Ehecatl Antonio; Maitland, Geoffrey C; Hellgardt, Klaus; Vassiliadis, Vassilios S

    2015-12-01

    This paper investigates the scaling-up of cyanobacterial biomass cultivation and biohydrogen production from laboratory to industrial scale. Two main aspects are investigated and presented, which to the best of our knowledge have never been addressed, namely the construction of an accurate dynamic model to simulate cyanobacterial photo-heterotrophic growth and biohydrogen production and the prediction of the maximum biomass and hydrogen production in different scales of photobioreactors. To achieve the current goals, experimental data obtained from a laboratory experimental setup are fitted by a dynamic model. Based on the current model, two key original findings are made in this work. First, it is found that selecting low-chlorophyll mutants is an efficient way to increase both biomass concentration and hydrogen production particularly in a large scale photobioreactor. Second, the current work proposes that the width of industrial scale photobioreactors should not exceed 0.20 m for biomass cultivation and 0.05 m for biohydrogen production, as severe light attenuation can be induced in the reactor beyond this threshold.

  4. Canonical Height Functions For Monomial Maps

    CERN Document Server

    Lin, Jan-Li

    2012-01-01

    We show that the canonical height function defined by Silverman does not have the Northcott finiteness property in general. We develop a new canonical height function for monomial maps. In certain cases, this new canonical height function has nice properties.

  5. Measuring Ice Sheet Height with ICESat-2

    Science.gov (United States)

    Walsh, K.; Smith, B.; Neumann, T.; Hancock, D.

    2015-12-01

    ICESat-2 is NASA's next-generation laser altimeter, designed to measure changes in ice sheet height and sea ice freeboard. Over the ice sheets, it will use a continuous repeat-track pointing strategy to ensure that it accurately measures elevation changes along a set of reference tracks. Over most of the area of Earth's ice sheets, ICESat-2 will provide coverage with a track-to-track spacing better than ~3 km. The onboard ATLAS instrument will use a photon-counting approach to provide a global geolocated photon point cloud, which is then converted into surface-specific elevation data sets. In this presentation, we will outline our strategy for taking the low-level photon point cloud and turning it into measurements posted at 20 m along-track for a set of pre-defined reference points by (1) selecting groups of photon events (PEs) around each along-track point, (2) refining the initial PE selection by fitting selected PEs with an along-track segment model and eliminating outliers to the model, (3) applying histogram-based corrections to the surface height based on the residuals to the along-track segment model, (4) calculate error estimates based on estimates of relative contributions of signal and noise PEs to the observed PE count, and (5) determining the final location and surface height of the along-track segment. These measurements are then corrected for short-scale (100-200 m) across-track surface topography around the reference points to develop a time series of land ice heights. The resulting data products will allow us to measure ice sheet elevation change with a point-for-point accuracy of a few centimeters over Earth's ice sheets.

  6. Correlation of fluid properties and geochemical parameters with heavy oil viscosity and density on trans-regional scale

    Energy Technology Data Exchange (ETDEWEB)

    Lehne, E.; Rojas, K.; McCarthy, K.; Taylor, S.D. [Schlumberger (Canada)

    2011-07-01

    Heavy oils around the world are characterized by high specific gravity and high contents of heavy components but their viscosity differs from one reservoir to another. This research aimed at finding correlations of geochemical characteristics with oil viscosity for heavy oil from different basins. This study was conducted on 15 heavy oil samples from northern and southern America and from Asia; the samples were characterized using gas chromatography, capillarity viscometer, data from stable carbon isotopes, SARA analysis, GC-FID and freezing point depression. Results showed that the degradation-viscosity correlation observed on a regional scale cannot be applied to the worldwide scale, and determined that, at that scale, oil viscosity depends on the original oil maturity and organofacies characteristics. In addition, biomarkers were found to help limit potential oil viscosity although they did not show a direct correlation. This study showed that original oil maturity and organofacies characteristics have to be taken into account in predictive models of oil viscosity.

  7. Height-Deterministic Pushdown Automata

    DEFF Research Database (Denmark)

    Nowotka, Dirk; Srba, Jiri

    2007-01-01

    of regular languages and still closed under boolean language operations, are considered. Several of such language classes have been described in the literature. Here, we suggest a natural and intuitive model that subsumes all the formalisms proposed so far by employing height-deterministic pushdown automata...

  8. Local-scale modelling of density-driven flow for the phases of repository operation and post-closure at Beberg

    Energy Technology Data Exchange (ETDEWEB)

    Jaquet, O.; Siegel, P. [Colenco Power Engineering Ltd, Baden-Daettwil (Switzerland)

    2004-09-01

    A hydrogeological model was developed for Beberg with the aim of evaluating the impact of a repository (for the operational and post-closure phases) while accounting for the effects of density-driven flow. Two embedded scales were taken into account for this modelling study: a local scale at which the granitic medium was considered as a continuum and a repository scale, where the medium is fractured and therefore was regarded to be discrete. The following step-wise approach was established to model density-driven flow at both repository and local scale: (a) modelling fracture networks at the repository scale, (b) upscaling the hydraulic properties to a continuum at local scale and (c) modelling density-driven flow to evaluate repository impact at local scale. The results demonstrate the strong impact of the repository on the flow field during the phase of operation. The distribution of the salt concentration is affected by a large upcoming effect with increased relative concentration and by the presence of fracture zones carrying freshwater from the surface. The concentrations obtained for the reference case, expressed in terms of percentage with respect to the maximum (prescribed) value in the model, are as follows: ca 30% for the phase of desaturation, and ca 20% for the resaturation phase. For the reference case, the impact of repository operations appears no longer visible after a resaturation period of about 20 years after repository closure; under resaturation conditions, evidence of the operational phase has already disappeared in terms of the observed hydraulic and concentration fields. Sensitivity calculations have proven the importance of explicitly discretising repository tunnels when assessing resaturation time and maximum concentration values. Furthermore, the definition of a fixed potential as boundary condition along the model's top surface is likely to provide underestimated values for the maximum concentration and overestimated flow rates in

  9. Density/area power-law models for separating multi-scale anomalies of ore and toxic elements in stream sediments in Gejiu mineral district, Yunnan Province, China

    Directory of Open Access Journals (Sweden)

    Q. Cheng

    2010-10-01

    Full Text Available This contribution introduces a fractal filtering technique newly developed on the basis of a spectral energy density vs. area power-law model in the context of multifractal theory. It can be used to map anisotropic singularities of geochemical landscapes created from geochemical concentration values in various surface media such as soils, stream sediments, tills and water. A geochemical landscape can be converted into a Fourier domain in which the spectral energy density is plotted against the area (in wave number units, and the relationship between the spectrum energy density (S and the area (A enclosed by the above-threshold spectrum energy density can be fitted by power-law models. Mixed geochemical landscape patterns can be fitted with different S-A power-law models in the frequency domain. Fractal filters can be defined according to these different S-A models and used to decompose the geochemical patterns into components with different self-similarities. The fractal filtering method was applied to a geochemical dataset from 7,349 stream sediment samples collected from Gejiu mineral district, which is famous for its word-class tin and copper production. Anomalies in three different scales were decomposed from total values of the trace elements As, Sn, Cu, Zn, Pb, and Cd. These anomalies generally correspond to various geological features and geological processes such as sedimentary rocks, intrusions, fault intersections and mineralization.

  10. A low cost, high energy density, and long cycle life potassium-sulfur battery for grid-scale energy storage.

    Science.gov (United States)

    Lu, Xiaochuan; Bowden, Mark E; Sprenkle, Vincent L; Liu, Jun

    2015-10-21

    A potassium-sulfur battery using K(+) -conducting beta-alumina as the electrolyte to separate a molten potassium metal anode and a sulfur cathode is presented. The results indicate that the battery can operate at as low as 150 °C with excellent performance. This study demonstrates a new type of high-performance metal-sulfur battery that is ideal for grid-scale energy-storage applications.

  11. STUDY OF NON-BOUSSINESQ EFFCET ON SEA SURFACE HEIGHT

    Institute of Scientific and Technical Information of China (English)

    CHEN Xian-yao; WANG Xuan; WANG Xiu-hong; QIAO Fang-li

    2004-01-01

    A set of equations was derived for a non-Boussinesq ocean model in this paper.A new time-splitting scheme was introduced which incorporates the 4th-order Runge-Kutta explicit scheme of low-frequency mode and an implicit scheme of high-frequency mode.With this model,potential temperature,salinity fields and sea surface height were calculated simultaneously such that the numerical error of extrapolation of density field from the current time level to the next one could be reduced while using the equation of mass conservation to determine sea surface height.The non-Boussinesq effect on the density field and sea surface height was estimated by numerical experiments in the final part of this paper.

  12. Energy Decomposition Analysis Based on Absolutely Localized Molecular Orbitals for Large-Scale Density Functional Theory Calculations in Drug Design.

    Science.gov (United States)

    Phipps, M J S; Fox, T; Tautermann, C S; Skylaris, C-K

    2016-07-12

    We report the development and implementation of an energy decomposition analysis (EDA) scheme in the ONETEP linear-scaling electronic structure package. Our approach is hybrid as it combines the localized molecular orbital EDA (Su, P.; Li, H. J. Chem. Phys., 2009, 131, 014102) and the absolutely localized molecular orbital EDA (Khaliullin, R. Z.; et al. J. Phys. Chem. A, 2007, 111, 8753-8765) to partition the intermolecular interaction energy into chemically distinct components (electrostatic, exchange, correlation, Pauli repulsion, polarization, and charge transfer). Limitations shared in EDA approaches such as the issue of basis set dependence in polarization and charge transfer are discussed, and a remedy to this problem is proposed that exploits the strictly localized property of the ONETEP orbitals. Our method is validated on a range of complexes with interactions relevant to drug design. We demonstrate the capabilities for large-scale calculations with our approach on complexes of thrombin with an inhibitor comprised of up to 4975 atoms. Given the capability of ONETEP for large-scale calculations, such as on entire proteins, we expect that our EDA scheme can be applied in a large range of biomolecular problems, especially in the context of drug design.

  13. Predicting tree heights for biomass estimates in tropical forests

    Directory of Open Access Journals (Sweden)

    Q. Molto

    2013-05-01

    Full Text Available The recent development of REDD+ mechanisms require reliable estimation of carbon stocks, especially in tropical forests that are particularly threatened by global changes. Even if tree height is a crucial variable to compute the above-ground forest biomass, tree heights are rarely measured in large-scale forest census because it requires consequent extra-effort. Tree height have thus to be predicted thanks to height models. Height and diameter of all trees above 10 cm of diameter were measured in thirty-three half-ha plots and nine one-ha plots throughout the northern French Guiana, an area with substantial climate and environmental gradients. We compared four different model shapes and found that the Michaelis–Menten shape was the most appropriate for the tree biomass prediction. Model parameters values were significantly different from one forest plot to another and neglecting these differences would lead to large errors in biomass estimates. Variables from the forest stand structure explained a sufficient part of the plot-to-plot variations of the height model parameters to affect the AGB predictions. In the forest stands dominated by small trees, the trees were found to have rapid height growth for small diameters. In forest stands dominated by larger trees, the trees were found to have the greatest heights for large diameters. The above-ground biomass estimation uncertainty of the forest plots was reduced by the use of the forest structure-based height model. It demonstrates the feasibility and the importance of height modeling in tropical forest for carbon mapping. Tree height is definitely an important variable for AGB estimations. When the tree heights are not measured in an inventory, they can be predicted with a height-diameter model. This model can account for plot-to plot variations in height-diameter relationship thank to variables describing the plots. The variables describing the stand structure of the plots are efficient for

  14. Airborne Crowd Density Estimation

    Science.gov (United States)

    Meynberg, O.; Kuschk, G.

    2013-10-01

    This paper proposes a new method for estimating human crowd densities from aerial imagery. Applications benefiting from an accurate crowd monitoring system are mainly found in the security sector. Normally crowd density estimation is done through in-situ camera systems mounted on high locations although this is not appropriate in case of very large crowds with thousands of people. Using airborne camera systems in these scenarios is a new research topic. Our method uses a preliminary filtering of the whole image space by suitable and fast interest point detection resulting in a number of image regions, possibly containing human crowds. Validation of these candidates is done by transforming the corresponding image patches into a low-dimensional and discriminative feature space and classifying the results using a support vector machine (SVM). The feature space is spanned by texture features computed by applying a Gabor filter bank with varying scale and orientation to the image patches. For evaluation, we use 5 different image datasets acquired by the 3K+ aerial camera system of the German Aerospace Center during real mass events like concerts or football games. To evaluate the robustness and generality of our method, these datasets are taken from different flight heights between 800 m and 1500 m above ground (keeping a fixed focal length) and varying daylight and shadow conditions. The results of our crowd density estimation are evaluated against a reference data set obtained by manually labeling tens of thousands individual persons in the corresponding datasets and show that our method is able to estimate human crowd densities in challenging realistic scenarios.

  15. All of the Sky: HEALPix Density Maps of Gaia-scale Datasets from the Database to the Desktop

    CERN Document Server

    Taylor, M B; Demleitner, M

    2016-01-01

    The Gaia Archive provides access to observations of around a billion sky sources. The primary access to this archive is via TAP services such as GACS and ARI-Gaia, which allow execution of SQL-like queries against a large remote database returning a result set of manageable size for client-side use. Such services are generally used for extracting relatively small source lists according to potentially complex selection criteria. But they can also be used to obtain statistical information about all, or a large fraction of, the observed sources by building histogram-like results. We examine here the practicalities of producing and consuming all-sky HEALPix weighted density maps in this way for Gaia and other large datasets. We present some modest requirements on TAP/RDBMS services to enable such queries, and discuss visualisation and serialization options for the results including some new capabilities in recent versions of TOPCAT.

  16. Linear-scaling density-functional simulations of charged point defects in Al2O3 using hierarchical sparse matrix algebra.

    Science.gov (United States)

    Hine, N D M; Haynes, P D; Mostofi, A A; Payne, M C

    2010-09-21

    We present calculations of formation energies of defects in an ionic solid (Al(2)O(3)) extrapolated to the dilute limit, corresponding to a simulation cell of infinite size. The large-scale calculations required for this extrapolation are enabled by developments in the approach to parallel sparse matrix algebra operations, which are central to linear-scaling density-functional theory calculations. The computational cost of manipulating sparse matrices, whose sizes are determined by the large number of basis functions present, is greatly improved with this new approach. We present details of the sparse algebra scheme implemented in the ONETEP code using hierarchical sparsity patterns, and demonstrate its use in calculations on a wide range of systems, involving thousands of atoms on hundreds to thousands of parallel processes.

  17. and the CMJ jump height

    Directory of Open Access Journals (Sweden)

    Struzik Artur

    2016-04-01

    Full Text Available Study aim: The elastic potential energy accumulated in the musculotendinous units during the countermovement phase of a jump adds up to the energy supplied by the contracting muscles used in the take-off phase. Consequently, the total mechanical energy used during the jump may reach higher values. Stiffness represents a quantitative measure of a body’s elastic properties. Therefore, the aim of this study was to establish the relationship between leg stiffness and the countermovement jump height.

  18. Effective Height Upper Bounds on Algebraic Tori

    CERN Document Server

    Habegger, Philipp

    2012-01-01

    The main emphasis will be on height upper bounds in the algebraic torus G^{n}_{m}. By height we will mean the absolute logarithmic Weil height. Section 3.2 contains a precise definition of this and other more general height functions. The first appendix gives a short overview of known results in the abelian case. The second appendix contains a few height bounds in Shimura varieties.

  19. Comment on "Scaling properties of information-theoretic quantities in density functional reactivity theory" by C. Rong, T. Lu, P. W. Ayers, P. K. Chattaraj and S. Liu, Phys. Chem. Chem. Phys., 2015, 17, 4977-4988.

    Science.gov (United States)

    Bohórquez, Hugo J

    2015-12-21

    The scaling properties of density functionals are key for fundamentally understanding density functional theory. Accordingly, the dependence of density functionals on the number of particles is of paramount relevance. The numerical exploration by Rong et al. addressed N-scaling for a set of quantum information quantities; they found linear relationships between each one of them and the electronic population for atoms, molecules, and atoms in molecules. The main motivation for their computational work was that the theoretical scaling of these quantities is unknown; however, these scaling properties can be analytically determined. Here I reveal the derivation of the N-scaling rules for the quantities studied by Rong et al. by following the procedure introduced in Comput. Theor. Chem., 2015, 1053, 38. In addition, a new atomic scaling rule explains the linear relationship between atomic populations and atomic values of the same quantum information quantities.

  20. An improved empirical formulation of an ionosphere bottomside electron density profile thickness parameter

    Science.gov (United States)

    Alazo-Cuartas, K.; Radicella, S. M.

    2017-10-01

    An improved empirical formulation for the characterization of the ;base point; of the bottomside ionospheric electron density profile is proposed. The ;base point; in an ionospheric layer is defined by the electron density profile height where the gradient dN/dh reaches a maximum. The difference between the height of the maximum electron density and the height of the ;base point; is proportional to the ionospheric F2 layer thickness parameter B2. The previous empirical formula links the maximum value of dN/dh to foF2 and M(3000)F2 scaled from the ionograms. The new formulation adds a dependence on the solar zenith angle. The use of the new equation improves substantially the calculation of the B2 thickness parameter used in the NeQuick model.

  1. Extended clustering analyses to constrain the deflection angular scale and source density of the ultra-high-energy cosmic rays

    CERN Document Server

    Decerprit, Guillaume; Parizot, Etienne

    2011-01-01

    The search of a clustering signal in the arrival directions of ultra-high-energy cosmic rays (UHECRs) is a standard method to assess the level of anisotropy of the data sets under investigation. Here, we first show how to quantify the sensitivity of a UHECR detector to the detection of anisotropy, and then propose a new method that pushes forward the study of the two-point auto-correlation function, enabling one to put astrophysically meaningful constraints on both the effective UHECR source density and the angular deflections that these charged particles suffer while they propagate through the galactic and intergalactic magnetic fields. We apply the method to simulated data sets obtained under various astrophysical conditions, and show how the input model parameters can be estimated through our analysis, introducing the notion of "clustering similarity" (between data sets), to which we give a precise statistical meaning. We also study how the constraining power of the method is influenced by the size of the ...

  2. Twenty bone-mineral-density loci identified by large-scale meta-analysis of genome-wide association studies.

    Science.gov (United States)

    Rivadeneira, Fernando; Styrkársdottir, Unnur; Estrada, Karol; Halldórsson, Bjarni V; Hsu, Yi-Hsiang; Richards, J Brent; Zillikens, M Carola; Kavvoura, Fotini K; Amin, Najaf; Aulchenko, Yurii S; Cupples, L Adrienne; Deloukas, Panagiotis; Demissie, Serkalem; Grundberg, Elin; Hofman, Albert; Kong, Augustine; Karasik, David; van Meurs, Joyce B; Oostra, Ben; Pastinen, Tomi; Pols, Huibert A P; Sigurdsson, Gunnar; Soranzo, Nicole; Thorleifsson, Gudmar; Thorsteinsdottir, Unnur; Williams, Frances M K; Wilson, Scott G; Zhou, Yanhua; Ralston, Stuart H; van Duijn, Cornelia M; Spector, Timothy; Kiel, Douglas P; Stefansson, Kari; Ioannidis, John P A; Uitterlinden, André G

    2009-11-01

    Bone mineral density (BMD) is a heritable complex trait used in the clinical diagnosis of osteoporosis and the assessment of fracture risk. We performed meta-analysis of five genome-wide association studies of femoral neck and lumbar spine BMD in 19,195 subjects of Northern European descent. We identified 20 BMD loci that reached genome-wide significance (GWS; P GPR177), 2p21 (SPTBN1), 3p22 (CTNNB1), 4q21.1 (MEPE), 5q14 (MEF2C), 7p14 (STARD3NL), 7q21.3 (FLJ42280), 11p11.2 (LRP4, ARHGAP1, F2), 11p14.1 (DCDC5), 11p15 (SOX6), 16q24 (FOXL1), 17q21 (HDAC5) and 17q12 (CRHR1). The meta-analysis also confirmed at GWS level seven known BMD loci on 1p36 (ZBTB40), 6q25 (ESR1), 8q24 (TNFRSF11B), 11q13.4 (LRP5), 12q13 (SP7), 13q14 (TNFSF11) and 18q21 (TNFRSF11A). The many SNPs associated with BMD map to genes in signaling pathways with relevance to bone metabolism and highlight the complex genetic architecture that underlies osteoporosis and variation in BMD.

  3. Large-Scale Hybrid Density Functional Theory Calculations in the Condensed-Phase: Ab Initio Molecular Dynamics in the Isobaric-Isothermal Ensemble

    Science.gov (United States)

    Ko, Hsin-Yu; Santra, Biswajit; Distasio, Robert A., Jr.; Wu, Xifan; Car, Roberto

    Hybrid functionals are known to alleviate the self-interaction error in density functional theory (DFT) and provide a more accurate description of the electronic structure of molecules and materials. However, hybrid DFT in the condensed-phase has a prohibitively high associated computational cost which limits their applicability to large systems of interest. In this work, we present a general-purpose order(N) implementation of hybrid DFT in the condensed-phase using Maximally localized Wannier function; this implementation is optimized for massively parallel computing architectures. This algorithm is used to perform large-scale ab initio molecular dynamics simulations of liquid water, ice, and aqueous ionic solutions. We have performed simulations in the isothermal-isobaric ensemble to quantify the effects of exact exchange on the equilibrium density properties of water at different thermodynamic conditions. We find that the anomalous density difference between ice I h and liquid water at ambient conditions as well as the enthalpy differences between ice I h, II, and III phases at the experimental triple point (238 K and 20 Kbar) are significantly improved using hybrid DFT over previous estimates using the lower rungs of DFT This work has been supported by the Department of Energy under Grants No. DE-FG02-05ER46201 and DE-SC0008626.

  4. Densidade e qualidade dos estratos de forragem do capim Tanzânia (Panicum maximum Jacq. Cv. Tanzânia-1 manejado em diferentes alturas, sob pastejo Density bulk and quality of Tanzania grass layers (Panicum maximum Jacq.cv. Tanzania-1, at different heights in grazing

    Directory of Open Access Journals (Sweden)

    Geraldo Tadeu dos Santos

    2001-05-01

    Full Text Available O objetivo do trabalho foi avaliar o efeito de diferentes alturas (24; 26; 43; 45; 52; 62; 73 e 78 cm do pasto sobre a qualidade de forragem e estrutura do perfil do capim-Tanzânia, (Panicum maximum Jacq. cv. Tanzânia – 1 (Poaceae. Foram utilizados novilhos da raça Nelore sob pastejo com carga animal variável, por meio da técnica put and take. O delineamento experimental utilizado foi inteiramente casualizado, com duas repetições. A densidade de matéria seca total (DMT aumentou com o avanço no período experimental, enquanto a densidade de matéria seca de lâminas (DML não foi influenciada pelo período e pela altura do pasto. O estrato superior da pastagem foi a porção de maior qualidade, apresentando maior DML e maior teor de PB. Os estratos inferiores apresentaram menor qualidade, devido à maior DMT e menor DML, acarretando em maiores valores de FDA e FDN e menores teores de PB. O conteúdo de minerais das lâminas foi superior aos colmos, mantendo-se inalterado com relação aos estratos da pastagem.The effect of different sward heights (24; 26; 43; 45; 52; 62; 73 and 78 cm on forage quality and profile structure Tanzania grass, Panicum maximum Jacq. cv. Tanzania – 1 (Poaceae is provided. Nelore steers were used in grazing at variable stocking rates with put and take technique. The experimental design was completely randomized, with two replications. Total dry matter bulk densitity (TDMD increased during experimental period, while the leaf blade dry matter bulk density (LDMD was not influenced by period on by sward height. The upper layers had the best quality with higher LDMD and CP levels. Lower layers had the worst quality, due the higher TDMD and lower LDMD. This fact caused higher ADF and NDF levels and lower CP levels. Leaf blade mineral content was higher than that of stem, and remained unaltered in relation to the different layers.

  5. Encounter Probability of Individual Wave Height

    DEFF Research Database (Denmark)

    Liu, Z.; Burcharth, H. F.

    1998-01-01

    wave height corresponding to a certain exceedence probability within a structure lifetime (encounter probability), based on the statistical analysis of long-term extreme significant wave height. Then the design individual wave height is calculated as the expected maximum individual wave height...... associated with the design significant wave height, with the assumption that the individual wave heights follow the Rayleigh distribution. However, the exceedence probability of such a design individual wave height within the structure lifetime is unknown. The paper presents a method for the determination...... of the design individual wave height corresponding to an exceedence probability within the structure lifetime, given the long-term extreme significant wave height. The method can also be applied for estimation of the number of relatively large waves for fatigue analysis of constructions....

  6. Evolution of Small Scale Density Perturbations of Plasma and Charged Aerosol Particles in Polar Mesospheric Summer Echoes (PMSE) Layers%Evolution of Small Scale Density Perturbations of Plasma and Charged Aerosol Particles in Polar Mesospheric Summer Echoes (PMSE) Layers

    Institute of Scientific and Technical Information of China (English)

    胡祖权; 陈银华; 郑聚高; 刘昊; 郁明阳; 吴剑

    2011-01-01

    Time evolution of ionospheric D-region plasmas including the perturbations of electrons and charged aerosol particles is investigated under the conditions of polar mesosphere summer echoes (PMSE). It is shown that the time scale of decay of the electron density is in the order of an hour under typical PMSE conditions, in the majority of cases, the electron density is anticorrelated to the ion density, except that the radius of aerosol particles is greater than 50 nm. Also, the evolutions under varied parameters, such as the amplitude and width of perturbation, the aerosol particle radius, and the altitude of the PMSE occurrence are investigated. The obtained results are useful for interpreting the experimental observations.

  7. Etymological study of Wuthering Heights

    Institute of Scientific and Technical Information of China (English)

    张倩; 张露

    2013-01-01

    In Wuthering Heights, the main characters and places have been delicately designed and cautiously named, which have their special implications based on the characters’identity, status and personalities or the features of the places. Therefore, through analyzing the implied meanings of the characters and place names in this novel, this essay illustrates that the author pur-posefully failed Heathcliff’s revenge. Meanwhile, the theme of this novel-Emily’s ultimate concern for the social inequality-is naturally exposed to the reader.

  8. A macroecological analysis of SERA derived forest heights and implications for forest volume remote sensing.

    Directory of Open Access Journals (Sweden)

    Matthew Brolly

    Full Text Available Individual trees have been shown to exhibit strong relationships between DBH, height and volume. Often such studies are cited as justification for forest volume or standing biomass estimation through remote sensing. With resolution of common satellite remote sensing systems generally too low to resolve individuals, and a need for larger coverage, these systems rely on descriptive heights, which account for tree collections in forests. For remote sensing and allometric applications, this height is not entirely understood in terms of its location. Here, a forest growth model (SERA analyzes forest canopy height relationships with forest wood volume. Maximum height, mean, H₁₀₀, and Lorey's height are examined for variability under plant number density, resource and species. Our findings, shown to be allometrically consistent with empirical measurements for forested communities world-wide, are analyzed for implications to forest remote sensing techniques such as LiDAR and RADAR. Traditional forestry measures of maximum height, and to a lesser extent H₁₀₀ and Lorey's, exhibit little consistent correlation with forest volume across modeled conditions. The implication is that using forest height to infer volume or biomass from remote sensing requires species and community behavioral information to infer accurate estimates using height alone. SERA predicts mean height to provide the most consistent relationship with volume of the height classifications studied and overall across forest variations. This prediction agrees with empirical data collected from conifer and angiosperm forests with plant densities ranging between 10²-10⁶ plants/hectare and heights 6-49 m. Height classifications investigated are potentially linked to radar scattering centers with implications for allometry. These findings may be used to advance forest biomass estimation accuracy through remote sensing. Furthermore, Lorey's height with its specific relationship to

  9. A macroecological analysis of SERA derived forest heights and implications for forest volume remote sensing.

    Science.gov (United States)

    Brolly, Matthew; Woodhouse, Iain H; Niklas, Karl J; Hammond, Sean T

    2012-01-01

    Individual trees have been shown to exhibit strong relationships between DBH, height and volume. Often such studies are cited as justification for forest volume or standing biomass estimation through remote sensing. With resolution of common satellite remote sensing systems generally too low to resolve individuals, and a need for larger coverage, these systems rely on descriptive heights, which account for tree collections in forests. For remote sensing and allometric applications, this height is not entirely understood in terms of its location. Here, a forest growth model (SERA) analyzes forest canopy height relationships with forest wood volume. Maximum height, mean, H₁₀₀, and Lorey's height are examined for variability under plant number density, resource and species. Our findings, shown to be allometrically consistent with empirical measurements for forested communities world-wide, are analyzed for implications to forest remote sensing techniques such as LiDAR and RADAR. Traditional forestry measures of maximum height, and to a lesser extent H₁₀₀ and Lorey's, exhibit little consistent correlation with forest volume across modeled conditions. The implication is that using forest height to infer volume or biomass from remote sensing requires species and community behavioral information to infer accurate estimates using height alone. SERA predicts mean height to provide the most consistent relationship with volume of the height classifications studied and overall across forest variations. This prediction agrees with empirical data collected from conifer and angiosperm forests with plant densities ranging between 10²-10⁶ plants/hectare and heights 6-49 m. Height classifications investigated are potentially linked to radar scattering centers with implications for allometry. These findings may be used to advance forest biomass estimation accuracy through remote sensing. Furthermore, Lorey's height with its specific relationship to remote sensing

  10. A direct dynamical measurement of the Milky Way's disk surface density profile, disk scale length, and dark matter profile at 4 kpc < R < 9 kpc

    CERN Document Server

    Bovy, Jo

    2013-01-01

    We present and apply rigorous dynamical modeling with which we infer unprecedented constraints on the stellar and dark matter mass distribution within our Milky Way (MW), based on large sets of phase-space data on individual stars. Specifically, we model the dynamics of 16,269 G-type dwarfs from SEGUE, which sample 5 < R/kpc < 12 and 0.3 < |Z|/kpc < 3. We independently fit a parameterized MW potential and a three-integral, action-based distribution function (DF) to the phase-space data of 43 separate abundance-selected sub-populations (MAPs), accounting for the complex selection effects affecting the data. We robustly measure the total surface density within 1.1 kpc of the mid-plane to about 5% over the range 4.5< R/kpc < 9. Using metal-poor MAPs with small radial scale lengths as dynamical tracers probes 4.5 < R/kpc < 7, while MAPs with longer radial scale lengths sample 7 < R/kpc < 9. We measure the mass-weighted Galactic disk scale length to be R_d = 2.15+/-0.14 kpc, in agreem...

  11. On the Predictability of Hub Height Winds

    DEFF Research Database (Denmark)

    Draxl, Caroline

    Wind energy is a major source of power in over 70 countries across the world, and the worldwide share of wind energy in electricity consumption is growing. The introduction of signicant amounts of wind energy into power systems makes accurate wind forecasting a crucial element of modern electrical...... grids. These systems require forecasts with temporal scales of tens of minutes to a few days in advance at wind farm locations. Traditionally these forecasts predict the wind at turbine hub heights; this information is then converted by transmission system operators and energy companies into predictions...... of power output at wind farms. Since the power available in the wind is proportional to the wind speed cubed, even small wind forecast errors result in large power prediction errors. Accurate wind forecasts are worth billions of dollars annually; forecast improvements will result in reduced costs...

  12. An Examination of FORMOSAT-3/COSMIC Ionospheric Electron Density Profile: Data Quality Criteria and Comparisons with the IRI Model

    Directory of Open Access Journals (Sweden)

    Kuo-Feng Yang

    2009-01-01

    Full Text Available In this article, we analyze the properties of ionospheric electron density profiling retrieved from FORMOSAT-3/COSMIC radio occultation measurements. Two parameters, namely, the gradient and fluctuation of the topside electron density profile, serve as indicators to quantitatively describe the data quality of the retrieved electron density profile. On the basis of 8 month data (June 2006 - January 2007, we find that on average 93% of the electron density profiles have upper electron density gradients and electron density fluctuations smaller than -0.02 #/m3/m and 0.2, respectively, which can be treated as good data for further analysis. The same results are also achieved for the peak height of the electron density. After removing the questionable data, we compare the general behaviors of the electron density between FORMOSAT-3 and the IRI model. It is found that the global distributions of the peak height and the peak electron density for the FORMOSAT-3/COSMIC data are generally consistent with those for the IRI model. However, a significant difference between their scale heights of the topside electron density profiles is found. It suggests that the shape of the topside electron density profile in the IRI model should be revised accordingly such that it more closely resembles the real situation.

  13. Linear-scaling time-dependent density-functional theory (TDDFT) beyond the Tamm-Dancoff approximation: obtaining efficiency and accuracy with in situ optimised local orbitals

    CERN Document Server

    Zuehlsdorff, Tim J; Payne, Mike C; Haynes, Peter D

    2015-01-01

    We present a solution of the full TDDFT eigenvalue equation in the linear response formalism exhibiting a linear-scaling computational complexity with system size, without relying on the simplifying Tamm-Dancoff approximation (TDA). The implementation relies on representing the occupied and unoccupied subspace with two different sets of in situ optimised localised functions, yielding a very compact and efficient representation of the transition density matrix of the excitation with the accuracy associated with a systematic basis set. The TDDFT eigenvalue equation is solved using a preconditioned conjugate-gradients algorithm that is very memory-efficient. The algorithm is validated on a test molecule and a good agreement with results obtained from standard quantum chemistry packages is found, with the preconditioner yielding a significant improvement in convergence rates. The method developed in this work is then used to reproduce experimental results of the absorption spectrum of bacteriochlorophyll (BChl) i...

  14. Detection of large scale intrinsic ellipticity-density correlation from the Sloan Digital Sky Survey and implications for weak lensing surveys

    CERN Document Server

    Mandelbaum, R; Ishak, M; Seljak, U; Brinkmann, J; Mandelbaum, Rachel; Hirata, Christopher M.; Ishak, Mustapha; Seljak, Uros; Brinkmann, Jonathan

    2006-01-01

    The power spectrum of weak lensing shear caused by large-scale structure is an emerging tool for precision cosmology, in particular for measuring the effects of dark energy on the growth of structure at low redshift. One potential source of systematic error is intrinsic alignments of ellipticities of neighbouring galaxies (II correlation) that could mimic the correlations due to lensing. A related possibility pointed out by Hirata and Seljak (2004) is correlation between the intrinsic ellipticities of galaxies and the density field responsible for gravitational lensing shear (GI correlation). We present constraints on both the II and GI correlations using 265 908 spectroscopic galaxies from the SDSS, and using galaxies as tracers of the mass in the case of the GI analysis. The availability of redshifts in the SDSS allows us to select galaxies at small radial separations, which both reduces noise in the intrinsic alignment measurement and suppresses galaxy- galaxy lensing (which otherwise swamps the GI correla...

  15. Linear-scaling time-dependent density-functional theory beyond the Tamm-Dancoff approximation: Obtaining efficiency and accuracy with in situ optimised local orbitals

    Energy Technology Data Exchange (ETDEWEB)

    Zuehlsdorff, T. J., E-mail: tjz21@cam.ac.uk; Payne, M. C. [Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Hine, N. D. M. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Haynes, P. D. [Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Department of Physics, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Thomas Young Centre for Theory and Simulation of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom)

    2015-11-28

    We present a solution of the full time-dependent density-functional theory (TDDFT) eigenvalue equation in the linear response formalism exhibiting a linear-scaling computational complexity with system size, without relying on the simplifying Tamm-Dancoff approximation (TDA). The implementation relies on representing the occupied and unoccupied subspaces with two different sets of in situ optimised localised functions, yielding a very compact and efficient representation of the transition density matrix of the excitation with the accuracy associated with a systematic basis set. The TDDFT eigenvalue equation is solved using a preconditioned conjugate gradient algorithm that is very memory-efficient. The algorithm is validated on a small test molecule and a good agreement with results obtained from standard quantum chemistry packages is found, with the preconditioner yielding a significant improvement in convergence rates. The method developed in this work is then used to reproduce experimental results of the absorption spectrum of bacteriochlorophyll in an organic solvent, where it is demonstrated that the TDA fails to reproduce the main features of the low energy spectrum, while the full TDDFT equation yields results in good qualitative agreement with experimental data. Furthermore, the need for explicitly including parts of the solvent into the TDDFT calculations is highlighted, making the treatment of large system sizes necessary that are well within reach of the capabilities of the algorithm introduced here. Finally, the linear-scaling properties of the algorithm are demonstrated by computing the lowest excitation energy of bacteriochlorophyll in solution. The largest systems considered in this work are of the same order of magnitude as a variety of widely studied pigment-protein complexes, opening up the possibility of studying their properties without having to resort to any semiclassical approximations to parts of the protein environment.

  16. Linear-scaling time-dependent density-functional theory beyond the Tamm-Dancoff approximation: Obtaining efficiency and accuracy with in situ optimised local orbitals

    Science.gov (United States)

    Zuehlsdorff, T. J.; Hine, N. D. M.; Payne, M. C.; Haynes, P. D.

    2015-11-01

    We present a solution of the full time-dependent density-functional theory (TDDFT) eigenvalue equation in the linear response formalism exhibiting a linear-scaling computational complexity with system size, without relying on the simplifying Tamm-Dancoff approximation (TDA). The implementation relies on representing the occupied and unoccupied subspaces with two different sets of in situ optimised localised functions, yielding a very compact and efficient representation of the transition density matrix of the excitation with the accuracy associated with a systematic basis set. The TDDFT eigenvalue equation is solved using a preconditioned conjugate gradient algorithm that is very memory-efficient. The algorithm is validated on a small test molecule and a good agreement with results obtained from standard quantum chemistry packages is found, with the preconditioner yielding a significant improvement in convergence rates. The method developed in this work is then used to reproduce experimental results of the absorption spectrum of bacteriochlorophyll in an organic solvent, where it is demonstrated that the TDA fails to reproduce the main features of the low energy spectrum, while the full TDDFT equation yields results in good qualitative agreement with experimental data. Furthermore, the need for explicitly including parts of the solvent into the TDDFT calculations is highlighted, making the treatment of large system sizes necessary that are well within reach of the capabilities of the algorithm introduced here. Finally, the linear-scaling properties of the algorithm are demonstrated by computing the lowest excitation energy of bacteriochlorophyll in solution. The largest systems considered in this work are of the same order of magnitude as a variety of widely studied pigment-protein complexes, opening up the possibility of studying their properties without having to resort to any semiclassical approximations to parts of the protein environment.

  17. Excess seawater nutrients, enlarged algal symbiont densities and bleaching sensitive reef locations: 2. A regional-scale predictive model for the Great Barrier Reef, Australia.

    Science.gov (United States)

    Wooldridge, Scott A; Heron, Scott F; Brodie, Jon E; Done, Terence J; Masiri, Itsara; Hinrichs, Saskia

    2017-01-15

    A spatial risk assessment model is developed for the Great Barrier Reef (GBR, Australia) that helps identify reef locations at higher or lower risk of coral bleaching in summer heat-wave conditions. The model confirms the considerable benefit of discriminating nutrient-enriched areas that contain corals with enlarged (suboptimal) symbiont densities for the purpose of identifying bleaching-sensitive reef locations. The benefit of the new system-level understanding is showcased in terms of: (i) improving early-warning forecasts of summer bleaching risk, (ii) explaining historical bleaching patterns, (iii) testing the bleaching-resistant quality of the current marine protected area (MPA) network (iv) identifying routinely monitored coral health attributes, such as the tissue energy reserves and skeletal growth characteristics (viz. density and extension rates) that correlate with bleaching resistant reef locations, and (v) targeting region-specific water quality improvement strategies that may increase reef-scale coral health and bleaching resistance. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

  18. Counting Young Tableaux of Bounded Height

    Science.gov (United States)

    Bergeron, Francois; Gascon, Francis

    2000-03-01

    We show that formulas of Gessel, for the generating functions for Young standard tableaux of height bounded by k (see [2]), satisfy linear differential equations, with polynomial coefficients, equivalent to P-recurrences conjectured by Favreau, Krob and the first author (see [1]) for the number of bounded height tableaux and pairs of bounded height tableaux.

  19. Abiotic Controls on Macroscale Variations of Humid Tropical Forest Height

    Directory of Open Access Journals (Sweden)

    Yan Yang

    2016-06-01

    Full Text Available Spatial variation of tropical forest tree height is a key indicator of ecological processes associated with forest growth and carbon dynamics. Here we examine the macroscale variations of tree height of humid tropical forests across three continents and quantify the climate and edaphic controls on these variations. Forest tree heights are systematically sampled across global humid tropical forests with more than 2.5 million measurements from Geoscience Laser Altimeter System (GLAS satellite observations (2004–2008. We used top canopy height (TCH of GLAS footprints to grid the statistical mean and variance and the 90 percentile height of samples at 0.5 degrees to capture the regional variability of average and large trees globally. We used the spatial regression method (spatial eigenvector mapping-SEVM to evaluate the contributions of climate, soil and topography in explaining and predicting the regional variations of forest height. Statistical models suggest that climate, soil, topography, and spatial contextual information together can explain more than 60% of the observed forest height variation, while climate and soil jointly explain 30% of the height variations. Soil basics, including physical compositions such as clay and sand contents, chemical properties such as PH values and cation-exchange capacity, as well as biological variables such as the depth of organic matter, all present independent but statistically significant relationships to forest height across three continents. We found significant relations between the precipitation and tree height with shorter trees on the average in areas of higher annual water stress, and large trees occurring in areas with low stress and higher annual precipitation but with significant differences across the continents. Our results confirm other landscape and regional studies by showing that soil fertility, topography and climate may jointly control a significant variation of forest height and

  20. Notes on an Internal Boundary-Layer Height Formula

    Science.gov (United States)

    Savelyev, Sergiya.; Taylor, Petera.

    The derivation of the Panofsky-Dutton internal boundary-layer(IBL) height formula has been revisited. We propose that the upwindroughness length (rather than downwind) should be used in theformula and that a turbulent vertical velocity (w) ratherthan the surface friction velocity (u*) should be considered asthe appropriate scaling for the rate of propagation ofdisturbances into the turbulent flow. A published set ofwind-tunnel and atmospheric data for neutral stratification hasbeen used to investigate the influence of the magnitude ofroughness change on the IBL height.

  1. Validation of Ionosonde Electron Density Reconstruction Algorithms with IONOLAB-RAY in Central Europe

    Science.gov (United States)

    Gok, Gokhan; Mosna, Zbysek; Arikan, Feza; Arikan, Orhan; Erdem, Esra

    2016-07-01

    Ionospheric observation is essentially accomplished by specialized radar systems called ionosondes. The time delay between the transmitted and received signals versus frequency is measured by the ionosondes and the received signals are processed to generate ionogram plots, which show the time delay or reflection height of signals with respect to transmitted frequency. The critical frequencies of ionospheric layers and virtual heights, that provide useful information about ionospheric structurecan be extracted from ionograms . Ionograms also indicate the amount of variability or disturbances in the ionosphere. With special inversion algorithms and tomographical methods, electron density profiles can also be estimated from the ionograms. Although structural pictures of ionosphere in the vertical direction can be observed from ionosonde measurements, some errors may arise due to inaccuracies that arise from signal propagation, modeling, data processing and tomographic reconstruction algorithms. Recently IONOLAB group (www.ionolab.org) developed a new algorithm for effective and accurate extraction of ionospheric parameters and reconstruction of electron density profile from ionograms. The electron density reconstruction algorithm applies advanced optimization techniques to calculate parameters of any existing analytical function which defines electron density with respect to height using ionogram measurement data. The process of reconstructing electron density with respect to height is known as the ionogram scaling or true height analysis. IONOLAB-RAY algorithm is a tool to investigate the propagation path and parameters of HF wave in the ionosphere. The algorithm models the wave propagation using ray representation under geometrical optics approximation. In the algorithm , the structural ionospheric characteristics arerepresented as realistically as possible including anisotropicity, inhomogenity and time dependence in 3-D voxel structure. The algorithm is also used

  2. Estimating vehicle height using homographic projections

    Science.gov (United States)

    Cunningham, Mark F; Fabris, Lorenzo; Gee, Timothy F; Ghebretati, Jr., Frezghi H; Goddard, James S; Karnowski, Thomas P; Ziock, Klaus-peter

    2013-07-16

    Multiple homography transformations corresponding to different heights are generated in the field of view. A group of salient points within a common estimated height range is identified in a time series of video images of a moving object. Inter-salient point distances are measured for the group of salient points under the multiple homography transformations corresponding to the different heights. Variations in the inter-salient point distances under the multiple homography transformations are compared. The height of the group of salient points is estimated to be the height corresponding to the homography transformation that minimizes the variations.

  3. Global Unification Problem of the Height System

    Directory of Open Access Journals (Sweden)

    XU Houze

    2017-08-01

    Full Text Available Some fundamental problems on the establishment of the global unified height system, including the geometry and gravity definition of the normal height, the global unification of the regional height systems obtained from leveling measurements, and the determination of geoid potential W0 are discussed. The main conclusions are summarized:①The definition of normal height in the sense of geometry leveling and gravity theory is different, so that h-ζ≠HL, here h, ζ and HL are geodetic height, height anomaly and levelling height respectively. Instead of it, we found HL=h-ζ+∂γ/∂hζH, in the mountain area, the last correction term have to be added. ②Based on the merging of GNSS/gravity/regional leveling, the regional leveling height can be transformed into a global relative unified height system, however the value of geoid potential W0 is still needed in order to establish an absolute height system. ③W0 can be determinated from the modern geodetic techniques with a certain accuracy, but it is time variable, so that people may only define a global absolute unified height system in a fixed epoch.

  4. Surface height map estimation from a single image using convolutional neural networks

    Science.gov (United States)

    Zhou, Xiaowei; Zhong, Guoqiang; Qi, Lin; Dong, Junyu; Pham, Tuan D.; Mao, Jianzhou

    2017-02-01

    Surface height map estimation is an important task in high-resolution 3D reconstruction. This task differs from general scene depth estimation in the fact that surface height maps contain more high frequency information or fine details. Existing methods based on radar or other equipments can be used for large-scale scene depth recovery, but might fail in small-scale surface height map estimation. Although some methods are available for surface height reconstruction based on multiple images, e.g. photometric stereo, height map estimation directly from a single image is still a challenging issue. In this paper, we present a novel method based on convolutional neural networks (CNNs) for estimating the height map from a single image, without any equipments or extra prior knowledge of the image contents. Experimental results based on procedural and real texture datasets show the proposed algorithm is effective and reliable.

  5. Novel approach of high cell density recombinant bioprocess development: Optimisation and scale-up from microlitre to pilot scales while maintaining the fed-batch cultivation mode of E. coli cultures

    Directory of Open Access Journals (Sweden)

    Rimšeliene Renata

    2010-05-01

    Full Text Available Abstract Background Bioprocess development of recombinant proteins is time consuming and laborious as many factors influence the accumulation of the product in the soluble and active form. Currently, in most cases the developmental line is characterised by a screening stage which is performed under batch conditions followed by the development of the fed-batch process. Performing the screening already under fed-batch conditions would limit the amount of work and guarantee that the selected favoured conditions also work in the production scale. Results Here, for the first time, high throughput multifactorial screening of a cloning library is combined with the fed-batch technique in 96-well plates, and a strategy is directly derived for scaling to bioreactor scale. At the example of a difficult to express protein, an RNase inhibitor, it is demonstrated that screening of various vector constructs and growth conditions can be performed in a coherent line by (i applying a vector library with promoters and ribosome binding sites of different strength and various fusion partners together with (ii an early stage use of the fed-batch technology. It is shown that the EnBase® technology provides an easy solution for controlled cultivation conditions in the microwell scale. Additionally the high cell densities obtained provide material for various analyses from the small culture volumes. Crucial factors for a high yield of the target protein in the actual case were (i the fusion partner, (ii the use of of a mineral salt medium together with the fed-batch technique, and (iii the preinduction growth rate. Finally, it is shown that the favorable conditions selected in the microwell plate and shake flask scales also work in the bioreactor. Conclusions Cultivation media and culture conditions have a major impact on the success of a screening procedure. Therefore the application of controlled cultivation conditions is pivotal. The consequent use of fed

  6. Starcounts Redivivus. IV. Density Laws Through Photometric Parallaxes

    CERN Document Server

    Siegel, M H; Reid, I N; Thompson, I B

    2002-01-01

    In an effort to more precisely define the spatial distribution of Galactic field stars, we present an analysis of the photometric parallaxes of 70,000 stars covering nearly 15 square degrees in seven Kapteyn Selected Areas. We address the affects of Malmquist Bias, subgiant/giant contamination, metallicity and binary stars upon the derived density laws. The affect of binary stars is the most significant. We find that while the disk-like populations of the Milky Way are easily constrained in a simultaneous analysis of all seven fields, no good simultaneous solution for the halo is found. We have applied halo density laws taken from other studies and find that the Besancon flattened power law halo model (c/a=0.6, r^-2.75) produces the best fit to our data. With this halo, the thick disk has a scale height of 750 pc with an 8.5% normalization to the old disk. The old disk scale height is 280-300 pc. Corrected for a binary fraction of 50%, these scale heights are 940 pc and 350-375 pc, respectively. Even with thi...

  7. Influence of real and virtual heights on standing balance.

    Science.gov (United States)

    Cleworth, Taylor W; Horslen, Brian C; Carpenter, Mark G

    2012-06-01

    Fear and anxiety induced by threatening scenarios, such as standing on elevated surfaces, have been shown to influence postural control in young adults. There is also a need to understand how postural threat influences postural control in populations with balance deficits and risk of falls. However, safety and feasibility issues limit opportunities to place such populations in physically threatening scenarios. Virtual reality (VR) has successfully been used to simulate threatening environments, although it is unclear whether the same postural changes can be elicited by changes in virtual and real threat conditions. Therefore, the purpose of this study was to compare the effects of real and virtual heights on changes to standing postural control, electrodermal activity (EDA) and psycho-social state. Seventeen subjects stood at low and high heights in both real and virtual environments matched in scale and visual detail. A repeated measures ANOVA revealed increases with height, independent of visual environment, in EDA, anxiety, fear, and center of pressure (COP) frequency, and decreases with height in perceived stability, balance confidence and COP amplitude. Interaction effects were seen for fear and COP mean position; where real elicited larger changes with height than VR. This study demonstrates the utility of VR, as simulated heights resulted in changes to postural, autonomic and psycho-social measures similar to those seen at real heights. As a result, VR may be a useful tool for studying threat related changes in postural control in populations at risk of falls, and to screen and rehabilitate balance deficits associated with fear and anxiety. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Double-hybrid density-functional theory made rigorous

    CERN Document Server

    Sharkas, Kamal; Savin, Andreas

    2010-01-01

    We provide a rigorous derivation of a class of double-hybrid approximations, combining Hartree-Fock exchange and second-order Moller-Plesset correlation with a semilocal exchange-correlation density functional. These double-hybrid approximations contain only one empirical parameter and use a density-scaled correlation energy functional. Neglecting density scaling leads to an one-parameter version of the standard double-hybrid approximations. We assess the performance of these double-hybrid schemes on representative test sets of atomization energies and reaction barrier heights, and we compare to other hybrid approximations, including range-separated hybrids. Our best one-parameter double-hybrid approximation, called 1DH-BLYP, roughly reproduces the two parameters of the standard B2-PLYP or B2GP-PLYP double-hybrid approximations, which shows that these methods are not only empirically close to an optimum for general chemical applications but are also theoretically supported.

  9. Linear-scaling density functional simulations of the effect of crystallographic structure on the electronic and optical properties of fullerene solvates.

    Science.gov (United States)

    Xue, Hong-Tao; Boschetto, Gabriele; Krompiec, Michal; Morse, Graham E; Tang, Fu-Ling; Skylaris, Chris-Kriton

    2017-02-15

    In this work, the crystal properties, HOMO and LUMO energies, band gaps, density of states, as well as the optical absorption spectra of fullerene C60 and its derivative phenyl-C61-butyric-acid-methyl-ester (PCBM) co-crystallised with various solvents such as benzene, biphenyl, cyclohexane, and chlorobenzene were investigated computationally using linear-scaling density functional theory with plane waves as implemented in the ONETEP program. Such solvates are useful materials as electron acceptors for organic photovoltaic (OPV) devices. We found that the fullerene parts contained in the solvates are unstable without solvents, and the interactions between fullerene and solvent molecules in C60 and PCBM solvates make a significant contribution to the cohesive energies of solvates, indicating that solvent molecules are essential to keep C60 and PCBM solvates stable. Both the band gap (Eg) and the HOMO and LUMO states of C60 and PCBM solvates are mainly determined by the fullerene parts contained in solvates. Chlorobenzene- and ortho-dichlorobenzene-solvated PCBM are the most promising electron-accepting materials among these solvates for increasing the driving force for charge separation in OPVs due to their relatively high LUMO energies. The UV-Vis absorption spectra of solvent-free C60 and PCBM crystals in the present work are similar to those of C60 and PCBM thin films shown in the literature. Changes in the absorption spectra of C60 solvates relative to the solvent-free C60 crystal are more significant than those of PCBM solvates due to the weaker effect of solvents on the π-stacking interactions between fullerene molecules in the latter solvates. The main absorptions for all C60 and PCBM crystals are located in the ultraviolet (UV) region.

  10. The importance of postural cues for determining eye height in immersive virtual reality.

    Science.gov (United States)

    Leyrer, Markus; Linkenauger, Sally A; Bülthoff, Heinrich H; Mohler, Betty J

    2015-01-01

    In human perception, the ability to determine eye height is essential, because eye height is used to scale heights of objects, velocities, affordances and distances, all of which allow for successful environmental interaction. It is well understood that eye height is fundamental to determine many of these percepts. Yet, how eye height itself is provided is still largely unknown. While the information potentially specifying eye height in the real world is naturally coincident in an environment with a regular ground surface, these sources of information can be easily divergent in similar and common virtual reality scenarios. Thus, we conducted virtual reality experiments where we manipulated the virtual eye height in a distance perception task to investigate how eye height might be determined in such a scenario. We found that humans rely more on their postural cues for determining their eye height if there is a conflict between visual and postural information and little opportunity for perceptual-motor calibration is provided. This is demonstrated by the predictable variations in their distance estimates. Our results suggest that the eye height in such circumstances is informed by postural cues when estimating egocentric distances in virtual reality and consequently, does not depend on an internalized value for eye height.

  11. The Effects of Vent Location, Event Scale, and Time Forecasts on Pyroclastic Density Current Hazard Maps at Campi Flegrei Caldera (Italy

    Directory of Open Access Journals (Sweden)

    Andrea Bevilacqua

    2017-09-01

    Full Text Available This study presents a new method for producing long-term hazard maps for pyroclastic density currents (PDC originating at Campi Flegrei caldera. Such method is based on a doubly stochastic approach and is able to combine the uncertainty assessments on the spatial location of the volcanic vent, the size of the flow and the expected time of such an event. The results are obtained by using a Monte Carlo approach and adopting a simplified invasion model based on the box model integral approximation. Temporal assessments are modeled through a Cox-type process including self-excitement effects, based on the eruptive record of the last 15 kyr. Mean and percentile maps of PDC invasion probability are produced, exploring their sensitivity to some sources of uncertainty and to the effects of the dependence between PDC scales and the caldera sector where they originated. Conditional maps representative of PDC originating inside limited zones of the caldera, or of PDC with a limited range of scales are also produced. Finally, the effect of assuming different time windows for the hazard estimates is explored, also including the potential occurrence of a sequence of multiple events. Assuming that the last eruption of Monte Nuovo (A.D. 1538 marked the beginning of a new epoch of activity similar to the previous ones, results of the statistical analysis indicate a mean probability of PDC invasion above 5% in the next 50 years on almost the entire caldera (with a probability peak of ~25% in the central part of the caldera. In contrast, probability values reduce by a factor of about 3 if the entire eruptive record is considered over the last 15 kyr, i.e., including both eruptive epochs and quiescent periods.

  12. Frequency Scale Factors for Some Double-Hybrid Density Functional Theory Procedures: Accurate Thermochemical Components for High-Level Composite Protocols.

    Science.gov (United States)

    Chan, Bun; Radom, Leo

    2016-08-09

    In the present study, we have obtained geometries and frequency scale factors for a number of double-hybrid density functional theory (DH-DFT) procedures. We have evaluated their performance for obtaining thermochemical quantities [zero-point vibrational energies (ZPVE) and thermal corrections for 298 K enthalpies (ΔH298) and 298 K entropies (S298)] to be used within high-level composite protocols (using the W2X procedure as a probe). We find that, in comparison with the previously prescribed protocol for optimization and frequency calculations (B3-LYP/cc-pVTZ+d), the use of contemporary DH-DFT methods such as DuT-D3 and DSD-type procedures leads to a slight overall improved performance compared with B3-LYP. A major strength of this approach, however, lies in the better robustness of the DH-DFT methods in that the largest deviations are notably smaller than those for B3-LYP. In general, the specific choices of the DH-DFT procedure and the associated basis set do not drastically change the performance. Nonetheless, we find that the DSD-PBE-P86/aug'-cc-pVTZ+d combination has a very slight edge over the others that we have examined, and we recommend its general use for geometry optimization and vibrational frequency calculations, in particular within high-level composite methods such as the higher-level members of the WnX series of protocols. The scale factors determined for DSD-PBE-P86/aug'-cc-pVTZ+d are 0.9830 (ZPVE), 0.9876 (ΔH298), and 0.9923 (S298).

  13. Imagery and fear influence height perception.

    Science.gov (United States)

    Clerkin, Elise M; Cody, Meghan W; Stefanucci, Jeanine K; Proffitt, Dennis R; Teachman, Bethany A

    2009-04-01

    The current study tested whether height overestimation is related to height fear and influenced by images of falling. To assess perceptual biases, participants high (n=65) versus low (n=64) in height fear estimated the vertical extents of two balconies using a visual matching task. On one of the balconies, participants engaged in an imagery exercise designed to enhance the subjective sense that they were acting in a dangerous environment by picturing themselves falling. As expected, we found that individuals overestimated the balcony's height more after they imagined themselves falling, particularly if they were already afraid of heights. These findings suggest that height fear may serve as a vulnerability factor that leads to perceptual biases when triggered by a stressor (in this case, images of falling).

  14. Statistical distribution of nonlinear random wave height

    Institute of Scientific and Technical Information of China (English)

    HOU; Yijun; GUO; Peifang; SONG; Guiting; SONG; Jinbao; YIN; Baoshu; ZHAO; Xixi

    2006-01-01

    A statistical model of random wave is developed using Stokes wave theory of water wave dynamics. A new nonlinear probability distribution function of wave height is presented. The results indicate that wave steepness not only could be a parameter of the distribution function of wave height but also could reflect the degree of wave height distribution deviation from the Rayleigh distribution. The new wave height distribution overcomes the problem of Rayleigh distribution that the prediction of big wave is overestimated and the general wave is underestimated. The prediction of small probability wave height value of new distribution is also smaller than that of Rayleigh distribution. Wave height data taken from East China Normal University are used to verify the new distribution. The results indicate that the new distribution fits the measurements much better than the Rayleigh distribution.

  15. Electon density profiles of the topside ionosphere

    Directory of Open Access Journals (Sweden)

    D. Bilitza

    2002-06-01

    Full Text Available The existing uncertainties about the electron density profiles in the topside ionosphere, i.e., in the height region from h m F 2 to ~ 2000 km, require the search for new data sources. The ISIS and Alouette topside sounder satellites from the sixties to the eighties recorded millions of ionograms but most were not analyzed in terms of electron density profiles. In recent years an effort started to digitize the analog recordings to prepare the ionograms for computerized analysis. As of November 2001 about 350 000 ionograms have been digitized from the original 7-track analog tapes. These data are available in binary and CDF format from the anonymous ftp site of the National Space Science Data Center. A search site and browse capabilities on CDAWeb assist the scientific usage of these data. All information and access links can be found at http://nssdc.gsfc.nasa.gov/space/isis/isis-status. html. This paper describes the ISIS data restoration effort and shows how the digital ionograms are automatically processed into electron density profiles from satellite orbit altitude (1400 km for ISIS-2 down to the F peak. Because of the large volume of data an automated processing algorithm is imperative. The TOPside Ionogram Scaler with True height algorithm TOPIST software developed for this task is successfully scaling ~ 70% of the ionograms. An «editing process» is available to manually scale the more difficult ionograms. The automated processing of the digitized ISIS ionograms is now underway, producing a much-needed database of topside electron density profiles for ionospheric modeling covering more than one solar cycle.

  16. Adult height, nutrition, and population health.

    Science.gov (United States)

    Perkins, Jessica M; Subramanian, S V; Davey Smith, George; Özaltin, Emre

    2016-03-01

    In this review, the potential causes and consequences of adult height, a measure of cumulative net nutrition, in modern populations are summarized. The mechanisms linking adult height and health are examined, with a focus on the role of potential confounders. Evidence across studies indicates that short adult height (reflecting growth retardation) in low- and middle-income countries is driven by environmental conditions, especially net nutrition during early years. Some of the associations of height with health and social outcomes potentially reflect the association between these environmental factors and such outcomes. These conditions are manifested in the substantial differences in adult height that exist between and within countries and over time. This review suggests that adult height is a useful marker of variation in cumulative net nutrition, biological deprivation, and standard of living between and within populations and should be routinely measured. Linkages between adult height and health, within and across generations, suggest that adult height may be a potential tool for monitoring health conditions and that programs focused on offspring outcomes may consider maternal height as a potentially important influence.

  17. Laccase mediator systems for eco-friendly production of medium-density fiberboard (MDF) on a pilot scale: physicochemical analysis of the reaction mechanism.

    Science.gov (United States)

    Euring, Markus; Rühl, Martin; Ritter, Nina; Kües, Ursula; Kharazipour, Alireza

    2011-10-01

    Increasing prices of petrochemical resins and possible harmful formaldehyde emissions from conventionally produced wood composites have resulted in increased interest in enzymatic binder systems as environmentally friendly alternatives for gluing lignocellulosic products. In this study, laccase mediator systems (LMSs) were used to activate lignin on wood fiber surfaces in the pilot-scale production of medium-density fiberboard (MDF) using a dry process. Three different mediators were applied: 4-hydroxybenzoic acid (HBA), 1-hydroxybenzotriazole (HBT), and acetosyringone (AS) of which HBA performed best. The mechanical properties of the manufactured boards produced with thermomechanical pulp (TMP) fibers, laccase, and HBA fulfilled all required European standards for wood-based panels. Oxygen consumption rates of the different LMSs and (13)C NMR spectroscopy results for treated TMP fibers were obtained for qualitative and quantitative analysis of lignin activation. The results show that reactions were most effective within the first 30 min of incubation. Oxygen consumption was fastest and highest for the LMS using HBA. (13)C NMR spectroscopy indicated the highest decrease of aromatic groups in the wood fiber lignin with this LMS. The data correlated well with the quality of the MDF. The required enzymatic reaction times allowed direct integration of the LMS into standard MDF production techniques. The results indicate that application of LMSs has a high potential for environmentally friendly MDF production. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Compensating effect of sap velocity for stand density leads to uniform hillslope-scale forest transpiration across a steep valley cross-section

    Science.gov (United States)

    Renner, Maik; Hassler, Sibylle; Blume, Theresa; Weiler, Markus; Hildebrandt, Anke; Guderle, Marcus; Schymanski, Stan; Kleidon, Axel

    2016-04-01

    Roberts (1983) found that forest transpiration is relatively uniform across different climatic conditions and suggested that forest transpiration is a conservative process compensating for environmental heterogeneity. Here we test this hypothesis at a steep valley cross-section composed of European Beech in the Attert basin in Luxemburg. We use sapflow, soil moisture, biometric and meteorological data from 6 sites along a transect to estimate site scale transpiration rates. Despite opposing hillslope orientation, different slope angles and forest stand structures, we estimated relatively similar transpiration responses to atmospheric demand and seasonal transpiration totals. This similarity is related to a negative correlation between sap velocity and site-average sapwood area. At the south facing sites with an old, even-aged stand structure and closed canopy layer, we observe significantly lower sap velocities but similar stand-average transpiration rates compared to the north-facing sites with open canopy structure, tall dominant trees and dense understorey. This suggests that plant hydraulic co-ordination allows for flexible responses to environmental conditions leading to similar transpiration rates close to the water and energy limits despite the apparent heterogeneity in exposition, stand density and soil moisture. References Roberts, J. (1983). Forest transpiration: A conservative hydrological process? Journal of Hydrology 66, 133-141.

  19. Scale Alpha and Beta of Quantitative Convergence and Chemical Reactivity Analysis in Dual Cholinesterase/Monoamine Oxidase Inhibitors for the Alzheimer Disease Treatment Using Density Functional Theory (DFT

    Directory of Open Access Journals (Sweden)

    Alejandro Morales-Bayuelo

    2013-01-01

    Full Text Available Molecular quantum similarity descriptors and Density Functional Theory (DFT based reactivity descriptors were studied for a series of cholinesterase/monoamine oxidase inhibitors used for the Alzheimer's disease treatment (AD. This theoretical study is expected to shed some light onto some molecular aspects that could contribute to the knowledge of the molecular mechanics behind interactions of these molecules with acetylcholinesterase (AChE and butyrylcholinesterase (BuChE, as well as with monoamine oxidase (MAO A and B. The Topogeometrical Superposition Algorithm to handle flexible molecules (TGSA-Flex alignment method was used to solve the problem of the relative orientation in the quantum similarity (QS field. Using the molecular quantum similarity (MQS field and reactivity descriptors supported in the DFT was possible the quantification of the steric and electrostatic effects through of the Coulomb and Overlap quantitative convergence scales (alpha and beta. In addition, an analysis of reactivity indexes is development, using global and local descriptors, identifying the binding sites and selectivity in the (cholinesterase/monoamine oxidase inhibitors, understanding the retrodonor process, and showing new insight for drugs design in a disease of difficult control as Alzheimer.

  20. Large-scale fabrication of linear low density polyethylene/layered double hydroxides composite films with enhanced heat retention, thermal, mechanical, optical and water vapor barrier properties

    Science.gov (United States)

    Xie, Jiazhuo; Zhang, Kun; Zhao, Qinghua; Wang, Qingguo; Xu, Jing

    2016-11-01

    Novel LDH intercalated with organic aliphatic long-chain anion was large-scale synthesized innovatively by high-energy ball milling in one pot. The linear low density polyethylene (LLDPE)/layered double hydroxides (LDH) composite films with enhanced heat retention, thermal, mechanical, optical and water vapor barrier properties were fabricated by melt blending and blowing process. FT IR, XRD, SEM results show that LDH particles were dispersed uniformly in the LLDPE composite films. Particularly, LLDPE composite film with 1% LDH exhibited the optimal performance among all the composite films with a 60.36% enhancement in the water vapor barrier property and a 45.73 °C increase in the temperature of maximum mass loss rate compared with pure LLDPE film. Furthermore, the improved infrared absorbance (1180-914 cm-1) of LLDPE/LDH films revealed the significant enhancement of heat retention. Therefore, this study prompts the application of LLDPE/LDH films as agricultural films with superior heat retention.

  1. Urban-scale mapping of PM2.5 distribution via data fusion between high-density sensor network and MODIS Aerosol Optical Depth

    Science.gov (United States)

    Ba, Yu Tao; xian Liu, Bao; Sun, Feng; Wang, Li hua; Tang, Yu jia; Zhang, Da wei

    2017-04-01

    High-resolution mapping of PM2.5 is the prerequisite for precise analytics and subsequent anti-pollution interventions. Considering the large variances of particulate distribution, urban-scale mapping is challenging either with ground-based fixed stations, with satellites or via models. In this study, a dynamic fusion method between high-density sensor network and MODIS Aerosol Optical Depth (AOD) was introduced. The sensor network was deployed in Beijing ( > 1000 fixed monitors across 16000 km2 area) to provide raw observations with high temporal resolution (sampling interval 5 km). The MODIS AOD was calibrated to provide distribution map with low temporal resolution (daily) and moderate spatial resolution ( = 3 km). By encoding the data quality and defects (e.g. could, reflectance, abnormal), a hybrid interpolation procedure with cross-validation generated PM2.5 distribution with both high temporal and spatial resolution. Several no-pollutant and high-pollution periods were tested to validate the proposed fusion method for capturing the instantaneous patterns of PM2.5 emission.

  2. Detailed deposition density maps constructed by large-scale soil sampling for gamma-ray emitting radioactive nuclides from the Fukushima Dai-ichi Nuclear Power Plant accident.

    Science.gov (United States)

    Saito, Kimiaki; Tanihata, Isao; Fujiwara, Mamoru; Saito, Takashi; Shimoura, Susumu; Otsuka, Takaharu; Onda, Yuichi; Hoshi, Masaharu; Ikeuchi, Yoshihiro; Takahashi, Fumiaki; Kinouchi, Nobuyuki; Saegusa, Jun; Seki, Akiyuki; Takemiya, Hiroshi; Shibata, Tokushi

    2015-01-01

    Soil deposition density maps of gamma-ray emitting radioactive nuclides from the Fukushima Dai-ichi Nuclear Power Plant (NPP) accident were constructed on the basis of results from large-scale soil sampling. In total 10,915 soil samples were collected at 2168 locations. Gamma rays emitted from the samples were measured by Ge detectors and analyzed using a reliable unified method. The determined radioactivity was corrected to that of June 14, 2011 by considering the intrinsic decay constant of each nuclide. Finally the deposition maps were created for (134)Cs, (137)Cs, (131)I, (129m)Te and (110m)Ag. The radioactivity ratio of (134)Cs-(137)Cs was almost constant at 0.91 regardless of the locations of soil sampling. The radioactivity ratios of (131)I and (129m)Te-(137)Cs were relatively high in the regions south of the Fukushima NPP site. Effective doses for 50 y after the accident were evaluated for external and inhalation exposures due to the observed radioactive nuclides. The radiation doses from radioactive cesium were found to be much higher than those from the other radioactive nuclides.

  3. Decreasing seagrass density negatively influences associated fauna.

    Science.gov (United States)

    McCloskey, Rosemary M; Unsworth, Richard K F

    2015-01-01

    Seagrass meadows globally are disappearing at a rapid rate with physical disturbances being one of the major drivers of this habitat loss. Disturbance of seagrass can lead to fragmentation, a reduction in shoot density, canopy height and coverage, and potentially permanent loss of habitat. Despite being such a widespread issue, knowledge of how such small scale change affects the spatial distribution and abundances of motile fauna remains limited. The present study investigated fish and macro faunal community response patterns to a range of habitat variables (shoot length, cover and density), including individual species habitat preferences within a disturbed and patchy intertidal seagrass meadow. Multivariate analysis showed a measurable effect of variable seagrass cover on the abundance and distribution of the fauna, with species specific preferences to both high and low seagrass cover seagrass. The faunal community composition varied significantly with increasing/decreasing cover. The faunal species composition of low cover seagrass was more similar to sandy control plots than to higher cover seagrass. Shannon Wiener Diversity (H') and species richness was significantly higher in high cover seagrass than in low cover seagrass, indicating increasing habitat value as density increases. The results of this study underline how the impacts of small scale disturbances from factors such as anchor damage, boat moorings and intertidal vehicle use on seagrass meadows that reduce shoot density and cover can impact upon associated fauna. These impacts have negative consequences for the delivery of ecosystem services such as the provision of nursery habitat.

  4. THE USE OF MATHEMATICAL MODELS FOR ESTIMATING WOOD BASIC DENSITY OF Eucalyptus sp CLONES

    Directory of Open Access Journals (Sweden)

    Cláudio Roberto Thiersch

    2006-09-01

    Full Text Available This study aimed at identifying at what point in the stem, in the longitudinal and cardinal direction, the pylodin penetration depth should be measured, for determining wood basic density, envisaging forestry inventory Data base used in compassed 36 parcels of 400 m2. Around the parcels 216 trees were sealed. Two clones (hybrid of E. grandis and E. urophylla, at the ages of 3; 4, 5 and 6 years, belonging to three different sites in East Brazil, encompassing East and Northeast of Espirito Santo state and south of Bahia state. In each measuring height of diameters it was also measured the penetration depth of the pylodin (in mm. The average basic density of scaled trees, was determined, departing from the cheaps, using the immersion method. The main conclusions were: The density equation, as function of the pylodin measures, age, site, diameters at 1.3m of ground and total height, was more precise, exact and stable than the density equation as function of pylodin, age, site and diameter, which in turn was more exact and stable than the density equation, as function of pylodin measures, age, site, diameter at a 1.3m of the ground and of total height, was precise and exact for all ages and sites, in dependent on if the pylodin measurements were taken in the South or in North fares, or in the average position between them. The height for measurement with pylodin can also be taken in the more ergonomic position of 1.3m. The density estimation, as a function of the measures with the pylodin, or as a function of the use of the pylodin, age, average dominant tree height an diameter at 1.3m of the ground, for both clones, was more precise when the measure with the pylodin was taken at the North face. The average tree basic density must always be taken by a specific equation for each clone, given that these equations differ statistically.

  5. Temperature and Density Measurements in a Quiet Coronal Streamer

    Science.gov (United States)

    Warren, Harry P.; Warshall, Andrew D.

    2002-06-01

    Many previous studies have used emission line or broadband filter ratios to infer the presence of temperature gradients in the quiet solar corona. Recently it has been suggested that these temperature gradients are not real, but result from the superposition of isothermal loops with different temperatures and density scale heights along the line of sight. A model describing this hydrostatic weighting bias has been developed by Aschwanden & Acton. In this paper we present the application of the Aschwanden & Acton differential emission measure model to Solar and Heliospheric Observatory Solar Ultraviolet Measurement of Emitted Radiation (SUMER) observations of a quiet coronal streamer. Simultaneous Yohkoh soft X-ray telescope (SXT) observations show increases in the filter ratios with height above the limb, indicating an increase in temperature. The application of the Aschwanden & Acton model to these SUMER data, however, show that the temperature is constant with height and that the distribution of temperatures in the corona is much too narrow for the hydrostatic weighting bias to have any effect on the SXT filter ratios. We consider the possibility that there is a tenuous hot component (~3 MK) that accounts for the SXT observations. We find that a hot plasma with an emission measure sufficient to reproduce the observed SXT fluxes would also produce significant count rates in the high-temperature emission lines in the SUMER wavelength range. These lines are not observed, and we conclude that the SUMER spectra are not consistent with the SXT filter ratio temperatures. Calculations from a hydrodynamic loop model suggest that nonuniform footpoint heating may be consistent with the temperatures and densities observed at most heights, consistent with the recent analysis of relatively cool (~1 MK) active region loops. We also find, however, that at the lowest heights the observed densities are smaller than those predicted by uniform or footpoint heating.

  6. A site dependent top height growth model for hybrid aspen

    Institute of Scientific and Technical Information of China (English)

    Tord Johansson

    2013-01-01

    In this study height growth models for hybrid aspen were developed using three growth equations. The mean age of the hybrid aspen was 21 years (range 15−51 years) with a mean stand density of 946 stems ha-1 (87−2374) and a mean diameter at breast height (over bark) of 19.6 cm (8.5−40.8 cm). Site index was also examined in relation to soil type. Multiple samples were collected for three types of soil: light clay, medium clay and till. Site index curves were constructed using the col-lected data and compared with published reports. A number of dynamic equations were assessed for modeling top-height growth from total age. A Generalized Algebraic Difference Approach model derived by Cieszewski (2001) performed the best. This model explained 99% of the observed variation in tree height growth and exhibited no apparent bias across the range of predicted site indices. There were no significant differences between the soil types and site indices.

  7. Evolutionary perspectives on human height variation

    NARCIS (Netherlands)

    Stulp, Gert; Barrett, Louise

    2016-01-01

    Human height is a highly variable trait, both within and between populations, has a high heritability, and influences the manner in which people behave and are treated in society. Although we know much about human height, this information has rarely been brought together in a comprehensive, systemat

  8. 47 CFR 95.51 - Antenna height.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Antenna height. 95.51 Section 95.51... SERVICES General Mobile Radio Service (GMRS) § 95.51 Antenna height. (a) Certain antenna structures used in... this chapter. (b) The antenna for a small base station or for a small control station must not be...

  9. Construction of a high-density genetic map for sesame based on large scale marker development by specific length amplified fragment (SLAF) sequencing

    Science.gov (United States)

    2013-01-01

    Background The genetics and molecular biology of sesame has only recently begun to be studied even though sesame is an important oil seed crop. A high-density genetic map for sesame has not been published yet due to a lack of sufficient molecular markers. Specific length amplified fragment sequencing (SLAF-seq) is a recently developed high-resolution strategy for large-scale de novo SNP discovery and genotyping. SLAF-seq was employed in this study to obtain sufficient markers to construct a high-density genetic map for sesame. Results In total, 28.21 Gb of data containing 201,488,285 pair-end reads was obtained after sequencing. The average coverage for each SLAF marker was 23.48-fold in the male parent, 23.38-fold in the female parent, and 14.46-fold average in each F2 individual. In total, 71,793 high-quality SLAFs were detected of which 3,673 SLAFs were polymorphic and 1,272 of the polymorphic markers met the requirements for use in the construction of a genetic map. The final map included 1,233 markers on the 15 linkage groups (LGs) and was 1,474.87 cM in length with an average distance of 1.20 cM between adjacent markers. To our knowledge, this map is the densest genetic linkage map to date for sesame. 'SNP_only’ markers accounted for 87.51% of the markers on the map. A total of 205 markers on the map showed significant (P sesame. The map was constructed using an F2 population and the SLAF-seq approach, which allowed the efficient development of a large number of polymorphic markers in a short time. Results of this study will not only provide a platform for gene/QTL fine mapping, map-based gene isolation, and molecular breeding for sesame, but will also serve as a reference for positioning sequence scaffolds on a physical map, to assist in the process of assembling the sesame genome sequence. PMID:24060091

  10. Construction of a high-density genetic map for sesame based on large scale marker development by specific length amplified fragment (SLAF) sequencing.

    Science.gov (United States)

    Zhang, Yanxin; Wang, Linhai; Xin, Huaigen; Li, Donghua; Ma, Chouxian; Ding, Xia; Hong, Weiguo; Zhang, Xiurong

    2013-09-24

    The genetics and molecular biology of sesame has only recently begun to be studied even though sesame is an important oil seed crop. A high-density genetic map for sesame has not been published yet due to a lack of sufficient molecular markers. Specific length amplified fragment sequencing (SLAF-seq) is a recently developed high-resolution strategy for large-scale de novo SNP discovery and genotyping. SLAF-seq was employed in this study to obtain sufficient markers to construct a high-density genetic map for sesame. In total, 28.21 Gb of data containing 201,488,285 pair-end reads was obtained after sequencing. The average coverage for each SLAF marker was 23.48-fold in the male parent, 23.38-fold in the female parent, and 14.46-fold average in each F2 individual. In total, 71,793 high-quality SLAFs were detected of which 3,673 SLAFs were polymorphic and 1,272 of the polymorphic markers met the requirements for use in the construction of a genetic map. The final map included 1,233 markers on the 15 linkage groups (LGs) and was 1,474.87 cM in length with an average distance of 1.20 cM between adjacent markers. To our knowledge, this map is the densest genetic linkage map to date for sesame. 'SNP_only' markers accounted for 87.51% of the markers on the map. A total of 205 markers on the map showed significant (P sesame. The map was constructed using an F2 population and the SLAF-seq approach, which allowed the efficient development of a large number of polymorphic markers in a short time. Results of this study will not only provide a platform for gene/QTL fine mapping, map-based gene isolation, and molecular breeding for sesame, but will also serve as a reference for positioning sequence scaffolds on a physical map, to assist in the process of assembling the sesame genome sequence.

  11. Adjustments of the TaD electron density reconstruction model with GNSS-TEC parameters for operational application purposes

    Directory of Open Access Journals (Sweden)

    Belehaki Anna

    2012-12-01

    Full Text Available Validation results on the latest version of TaD model (TaDv2 show realistic reconstruction of the electron density profiles (EDPs with an average error of 3 TECU, similar to the error obtained from GNSS-TEC calculated paremeters. The work presented here has the aim to further improve the accuracy of the TaD topside reconstruction, adjusting the TEC parameter calculated from TaD model with the TEC parameter calculated by GNSS transmitting RINEX files provided by receivers co-located with the Digisondes. The performance of the new version is tested during a storm period demonstrating further improvements in respect to the previous version. Statistical comparison of modeled and observed TEC confirms the validity of the proposed adjustment. A significant benefit of the proposed upgrade is that it facilitates the real-time implementation of TaD. The model needs a reliable measure of the scale height at the peak height, which is supposed to be provided by Digisondes. Oftenly, the automatic scaling software fails to correctly calculate the scale height at the peak, Hm, due to interferences in the receiving signal. Consequently the model estimated topside scale height is wrongly calculated leading to unrealistic results for the modeled EDP. The proposed TEC adjustment forces the model to correctly reproduce the topside scale height, despite the inaccurate values of Hm. This adjustment is very important for the application of TaD in an operational environment.

  12. An efficient positive potential-density pair expansion for modelling galaxies

    CERN Document Server

    Rojas-Niño, Armando; Aguilar, Luis; Delorme, Maxime

    2016-01-01

    We present a novel positive potential-density pair expansion for modelling galaxies, based on the Miyamoto-Nagai (MN) disc. By using three sets of such discs, each one of them aligned along each symmetry axis, we are able to reconstruct a broad range of potentials that correspond to density profiles from exponential discs to 3D power law models with varying triaxiality (henceforth simply "twisted" models). We increase the efficiency of our expansion by allowing the scale length parameter of each disc to be negative. We show that, for suitable priors on the scale length and height parameters, these "MNn discs" have just one negative density minimum. This allows us to ensure global positivity by demanding that the total density at the global minimum is positive. We find that at better than 10\\% accuracy in our density reconstruction, we can represent a radial and vertical exponential disc over $0.1-10$ scale lengths/heights with 4 MNn discs, an NFW profile over $0.1-10$ scale lengths with 4 MNn discs, and a twi...

  13. Variations of the meteor echo heights at Beijing and Mohe, China

    Science.gov (United States)

    Liu, Libo; Liu, Huixin; Chen, Yiding; Le, Huijun; Sun, Yang-Yi; Ning, Baiqi; Hu, Lianhuan; Wan, Weixing

    2017-01-01

    Detecting the changing of the upper atmosphere is an important and challenging issue. The change in the meteor peak heights observed by a meteor radar should contain information of the neutral density in the meteoroid ablation region. In this work, observations from the VHF all-sky meteor radars operated at Beijing (40.3°N, 116.2°E) and Mohe (53.5°N, 122.3°E), China, are collected to explore the temporal patterns of the meteor peak heights. The daily meteor peak height is determined through a least squares fitting of the height profile of meteor radar echoes under a normal distribution assumption. There are considerable seasonal variations in the meteor peak heights, being dominated by an annual component at Beijing and a semiannual one at Mohe. Moreover, the Ensemble Empirical Mode Decomposition (EEMD) is employed to determine the overall trends in the series of the meteor peak heights. The EEMD analysis reveals an overall decrease in the meteor peak heights at both stations, indicating the descending trend in neutral density near 90 km altitude at middle latitudes. The meteor peak heights show a rather weak solar activity effect at Beijing, which is different from the positive effects reported at some other sites.

  14. The perfect ash-storm: large-scale Pyroclastic Density Current experiments reveal highly mobile, self-fluidising and air-cushioned flow transport regime

    Science.gov (United States)

    Lube, G.; Cronin, S. J.; Breard, E.; Valentine, G.; Bursik, M. I.; Hort, M. K.; Freundt, A.

    2013-12-01

    We report on the first systematic series of large-scale Pyroclastic Density Current (PDC) experiments using the New Zealand PDC Generator, a novel international research facility in Physical Volcanology recently commissioned at Massey University. Repeatable highly energetic and hot PDCs are synthesized by the controlled ';eruption column-collapse' of up to 3500 kg of homogenously aerated Taupo ignimbrite material from a 15 m-elevated hopper onto an instrumented inclined flume. At discharge rates between 250-1300 kg/s and low- to moderate gas injection rates (yielding initial solids concentration of 15-70 vol%) channelized gas-particle mixture flows life-scaled to dense PDCs can be generated. The flow fronts of the currents reach velocities of up to 9.5 m/s over their first 12 m of travel and rapidly develop strong vertical density stratification. The PDCs typically form a highly mobile, surge that also laterally escapes the flume boundaries. Depending on the PDC starting conditions underflows with 1-45 vol% solids concentration are formed, while the upper surge contains <<1 vol.% solids. A characteristic feature of the underflow is the occurrence of 'ignitive' front breakouts, producing jetted lobes that accelerate outward from the flow front, initially forming a lobe-cleft structure, followed by segregation downslope into multiple flow pulses. Depending on initial solids concentration and discharge rate, stratified, dune-bedded and inversely graded bedforms are created whose thicknesses are remarkably uniform along the medial to distal runout path characterising highly mobile flow runout. Along with high-speed video footage we present time-series data of basal arrays of load- and gas-pore pressure transducers to characterise the mobile dense underflows. Data shows that the PDCs are comprised of a turbulent coarse-grained and air-ingesting front with particle-solids concentrations of 1-5 vol%. The front shows a brief phase of negative pore pressure due to the

  15. The height of the atmospheric boundary layer during unstable conditions

    Energy Technology Data Exchange (ETDEWEB)

    Gryning, S.E.

    2005-11-01

    The height of the convective atmospheric boundary layer, also called the mixed-layer, is one of the fundamental parameters that characterise the structure of the atmosphere near the ground. It has many theoretical and practical applications such as the prediction of air pollution concentrations, surface temperature and the scaling of turbulence. However, as pointed out by Builtjes (2001) in a review paper on Major Twentieth Century Milestones in Air Pollution Modelling and Its Application, the weakest point in meteorology data is still the determination of the height of the mixed-layer, the so-called mixing height. A simple applied model for the height of the mixed-layer over homogeneous terrain is suggested in chapter 2. It is based on a parameterised budget for the turbulent kinetic energy. In the model basically three terms - the spin-up term and the production of mechanical and convective turbulent kinetic energy - control the growth of the mixed layer. The interplay between the three terms is related to the meteorological conditions and the height of the mixed layer. A stable layer, the so-called entrainment zone, which is confined between the mixed layer and the free air above, caps the mixed layer. A parameterisation of the depth of the entrainment zone is also suggested, and used to devise a combined model for the height of the mixed layer and the entrainment zone. Another important aspect of the mixed layer development exists in coastal areas where an internal boundary layer forms downwind from the coastline. A model for the growth of the internal boundary layer is developed in analogy with the model for mixed layer development over homogeneous terrain. The strength of this model is that it can operate on a very fine spatial resolution with minor computer resources. Chapter 3 deals with the validation of the models. It is based in parts on data from the literature, and on own measurements. For the validation of the formation of the internal boundary layer

  16. Azimuthal and radial variations in sap flux density and effects on stand-scale transpiration estimates in a Japanese cedar forest.

    Science.gov (United States)

    Shinohara, Yoshinori; Tsuruta, Kenji; Ogura, Akira; Noto, Fumikazu; Komatsu, Hikaru; Otsuki, Kyoichi; Maruyama, Toshisuke

    2013-05-01

    Understanding radial and azimuthal variation, and tree-to-tree variation, in sap flux density (Fd) as sources of uncertainty is important for estimating transpiration using sap flow techniques. In a Japanese cedar (Cryptomeria japonica D. Don.) forest, Fd was measured at several depths and aspects for 18 trees, using heat dissipation (Granier-type) sensors. We observed considerable azimuthal variation in Fd. The coefficient of variation (CV) calculated from Fd at a depth of 0-20 mm (Fd1) and Fd at a depth of 20-40 mm (Fd2) ranged from 6.7 to 37.6% (mean = 28.3%) and from 19.6 to 62.5% (mean = 34.6%) for the -azimuthal directions. Fd at the north aspect averaged for nine trees, for which azimuthal measurements were made, was -obviously smaller than Fd at the other three aspects (i.e., west, south and east) averaged for the nine trees. Fd1 averaged for the nine trees was significantly larger than Fd2 averaged for the nine trees. The error for stand-scale transpiration (E) estimates caused by ignoring the azimuthal variation was larger than that caused by ignoring the radial variation. The error caused by ignoring tree-to-tree variation was larger than that caused by ignoring both radial and azimuthal variations. Thus, tree-to-tree variation in Fd would be more important than both radial and azimuthal variations in Fd for E estimation. However, Fd for each tree should not be measured at a consistent aspect but should be measured at various aspects to make accurate E estimates and to avoid a risk of error caused by the relationship of Fd to aspect.

  17. Mapping ionospheric backscatter measured by the SuperDARN HF radars – Part 1: A new empirical virtual height model

    Directory of Open Access Journals (Sweden)

    T. K. Yeoman

    2008-05-01

    Full Text Available Accurately mapping the location of ionospheric backscatter targets (density irregularities identified by the Super Dual Auroral Radar Network (SuperDARN HF radars can be a major problem, particularly at far ranges for which the radio propagation paths are longer and more uncertain. Assessing and increasing the accuracy of the mapping of scattering locations is crucial for the measurement of two-dimensional velocity structures on the small and meso-scale, for which overlapping velocity measurements from two radars need to be combined, and for studies in which SuperDARN data are used in conjunction with measurements from other instruments. The co-ordinates of scattering locations are presently estimated using a combination of the measured range and a model virtual height, assuming a straight line virtual propagation path. By studying elevation angle of arrival information of backscatterred signals from 5 years of data (1997–2001 from the Saskatoon SuperDARN radar we have determined the actual distribution of the backscatter target locations in range-virtual height space. This has allowed the derivation of a new empirical virtual height model that allows for a more accurate mapping of the locations of backscatter targets.

  18. Increased height in diabetes mellitus corresponds to the predicted and the adult height

    NARCIS (Netherlands)

    Scheffer-Marinus, PD; Links, TP; Drayer, NM

    1999-01-01

    This study was conducted to analyse the effect of childhood-onset diabetes mellitus on adult height. The height at time of diagnosis of 35 children with insulin-dependent diabetes mellitus (IDDM) was compared with growth reference data. Predictions of the adult height were made at the time of diagno

  19. Low Melt Height Solidification of Superalloys

    Science.gov (United States)

    Montakhab, Mehdi; Bacak, Mert; Balikci, Ercan

    2016-06-01

    Effect of a reduced melt height in the directional solidification of a superalloy has been investigated by two methods: vertical Bridgman (VB) and vertical Bridgman with a submerged baffle (VBSB). The latter is a relatively new technique and provides a reduced melt height ahead of the solidifying interface. A low melt height leads to a larger primary dendrite arm spacing but a lower mushy length, melt-back transition length, and porosity. The VBSB technique yields up to 38 pct reduction in the porosity. This may improve a component's mechanical strength especially in a creep-fatigue type dynamic loading.

  20. Carbon nanotube growth density control

    Science.gov (United States)

    Delzeit, Lance D. (Inventor); Schipper, John F. (Inventor)

    2010-01-01

    Method and system for combined coarse scale control and fine scale control of growth density of a carbon nanotube (CNT) array on a substrate, using a selected electrical field adjacent to a substrate surface for coarse scale density control (by one or more orders of magnitude) and a selected CNT growth temperature range for fine scale density control (by multiplicative factors of less than an order of magnitude) of CNT growth density. Two spaced apart regions on a substrate may have different CNT growth densities and/or may use different feed gases for CNT growth.

  1. Mixing-Height Time Series from Operational Ceilometer Aerosol-Layer Heights

    Science.gov (United States)

    Lotteraner, Christoph; Piringer, Martin

    2016-07-01

    A new method is described to derive mixing-height time series directly from aerosol-layer height data available from a Vaisala CL51 ceilometer. As complete as possible mixing-height time series are calculated by avoiding outliers, filling data gaps by linear interpolation, and smoothing. In addition, large aerosol-layer heights at night that can be interpreted as residual layers are not assigned as mixing heights. The resulting mixing-height time series, converted to an appropriate data format, can be used as input for dispersion calculations. Two case examples demonstrate in detail how the method works. The mixing heights calculated using ceilometer data are compared with values determined from radiosounding data at Vienna by applying the parcel, Heffter, and Richardson methods. The results of the parcel method, obtained from radiosonde profiles at noon, show the best fit to the ceilometer-derived mixing heights. For midnight radiosoundings, larger deviations between mixing heights from the ceilometer and those deduced from the potential temperature profiles of the soundings are found. We use data from two Vaisala CL51 ceilometers, operating in the Vienna area at an urban and rural site, respectively, during an overlapping period of about 1 year. In addition to the case studies, the calculated mixing-height time series are also statistically evaluated and compared, demonstrating that the ceilometer-based mixing height follows an expected daily and seasonal course.

  2. Mixing-Height Time Series from Operational Ceilometer Aerosol-Layer Heights

    Science.gov (United States)

    Lotteraner, Christoph; Piringer, Martin

    2016-11-01

    A new method is described to derive mixing-height time series directly from aerosol-layer height data available from a Vaisala CL51 ceilometer. As complete as possible mixing-height time series are calculated by avoiding outliers, filling data gaps by linear interpolation, and smoothing. In addition, large aerosol-layer heights at night that can be interpreted as residual layers are not assigned as mixing heights. The resulting mixing-height time series, converted to an appropriate data format, can be used as input for dispersion calculations. Two case examples demonstrate in detail how the method works. The mixing heights calculated using ceilometer data are compared with values determined from radiosounding data at Vienna by applying the parcel, Heffter, and Richardson methods. The results of the parcel method, obtained from radiosonde profiles at noon, show the best fit to the ceilometer-derived mixing heights. For midnight radiosoundings, larger deviations between mixing heights from the ceilometer and those deduced from the potential temperature profiles of the soundings are found. We use data from two Vaisala CL51 ceilometers, operating in the Vienna area at an urban and rural site, respectively, during an overlapping period of about 1 year. In addition to the case studies, the calculated mixing-height time series are also statistically evaluated and compared, demonstrating that the ceilometer-based mixing height follows an expected daily and seasonal course.

  3. Heating of the solar middle chromosphere by large-scale electric currents

    Science.gov (United States)

    Goodman, M. L.

    1995-01-01

    A global resistive, two-dimensional, time-dependent magnetohydrodynamic (MHD) model is used to introduce and support the hypothesis that the quiet solar middle chromosphere is heated by resistive dissipation of large-scale electric currents which fill most of its volume. The scale height and maximum magnitude of the current density are 400 km and 31.3 m/sq m, respectively. The associated magnetic field is almost horizontal, has the same scale height as the current density, and has a maximum magnitude of 153 G. The current is carried by electrons flowing across magnetic field lines at 1 m/s. The resistivity is the electron contribution to the Pedersen resitivity for a weakly ionized, strongly magnetized, hydrogen gas. The model does not include a driving mechanism. Most of the physical quantities in the model decrease exponentially with time on a resistive timescale of 41.3 minutes. However, the initial values and spatial; dependence of these quantities are expected to be essentially the same as they would be if the correct driving mechanism were included in a more general model. The heating rate per unit mass is found to be 4.5 x 10(exp 9) ergs/g/s, independent of height and latitude. The electron density scale height is found to be 800 km. The model predicts that 90% of the thermal energy required to heat the middle chromosphere is deposited in the height range 300-760 km above the temperature minimum. It is shown to be consistent to assume that the radiation rate per unit volume is proportional to the magnetic energy density, and then it follows that the heating rate per unit volume is also proportional to the energy from the photosphere into the overlying chromosphere are briefly discussed as possible driving mechanisms for establishing and maintaining the current system. The case in which part of or all of the current is carried by protons and metal ions, and the contribution of electron-proton scattering to the current are also considered, with the conclusion

  4. Heating of the solar middle chromosphere by large-scale electric currents

    Science.gov (United States)

    Goodman, M. L.

    1995-01-01

    A global resistive, two-dimensional, time-dependent magnetohydrodynamic (MHD) model is used to introduce and support the hypothesis that the quiet solar middle chromosphere is heated by resistive dissipation of large-scale electric currents which fill most of its volume. The scale height and maximum magnitude of the current density are 400 km and 31.3 m/sq m, respectively. The associated magnetic field is almost horizontal, has the same scale height as the current density, and has a maximum magnitude of 153 G. The current is carried by electrons flowing across magnetic field lines at 1 m/s. The resistivity is the electron contribution to the Pedersen resitivity for a weakly ionized, strongly magnetized, hydrogen gas. The model does not include a driving mechanism. Most of the physical quantities in the model decrease exponentially with time on a resistive timescale of 41.3 minutes. However, the initial values and spatial; dependence of these quantities are expected to be essentially the same as they would be if the correct driving mechanism were included in a more general model. The heating rate per unit mass is found to be 4.5 x 10(exp 9) ergs/g/s, independent of height and latitude. The electron density scale height is found to be 800 km. The model predicts that 90% of the thermal energy required to heat the middle chromosphere is deposited in the height range 300-760 km above the temperature minimum. It is shown to be consistent to assume that the radiation rate per unit volume is proportional to the magnetic energy density, and then it follows that the heating rate per unit volume is also proportional to the energy from the photosphere into the overlying chromosphere are briefly discussed as possible driving mechanisms for establishing and maintaining the current system. The case in which part of or all of the current is carried by protons and metal ions, and the contribution of electron-proton scattering to the current are also considered, with the conclusion

  5. Accuracy of LiDAR-based tree height estimation and crown recognition in a subtropical evergreen broad-leaved forest in Okinawa, Japan

    Directory of Open Access Journals (Sweden)

    Azita Ahmad Zawawi

    2015-04-01

    Full Text Available Aim of study: To present an approach for estimating tree heights, stand density and crown patches using LiDAR data in a subtropical broad-leaved forest. Area of study: The study was conducted within the Yambaru subtropical evergreen broad-leaved forest, Okinawa main island, Japan. Materials and methods: A digital canopy height model (CHM was extracted from the LiDAR data for tree height estimation and a watershed segmentation method was applied for the individual crown delineation. Dominant tree canopy layers were estimated using multi-scale filtering and local maxima detection. The LiDAR estimation results were then compared to the ground inventory data and a high resolution orthophoto image for accuracy assessment. Main results: A Wilcoxon matched pair test suggests that LiDAR data is highly capable of estimating tree height in a subtropical forest (z = 4.0, p = 0.345, but has limitation to detect small understory trees and a single tree delineation. The results show that there is a statistically significant different type of crown detection from LiDAR data over forest inventory (z = 0, p = 0.043. We also found that LiDAR computation results underestimated the stand density and overestimated the crown size. Research highlights: Most studies involving crown detection and tree height estimation have focused on the analysis of plantations, boreal forests and temperate forests, and less was conducted on tropical and/or subtropical forests. Our study tested the capability of LiDAR as an effective application for analyzing a highly dense forest

  6. 36 CFR 910.12 - Development density.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Development density. 910.12... DEVELOPMENT AREA Urban Planning and Design Concerns § 910.12 Development density. (a) Land would be developed... density within the building envelope delineated by specific height restrictions, but shall also establish...

  7. Height of lumbar discs measured from radiographs compared with degeneration and height classified from MR images

    Energy Technology Data Exchange (ETDEWEB)

    Frobin, W.; Brinckmann, P. [Muenster Univ. (Germany). Inst. fuer Experimentelle Biomechanik; Kramer, M.; Hartwig, E. [Ulm Univ. (Germany). Sektion fuer Unfallchirurgische Forschung und Biomechanik

    2001-02-01

    The relation between height of lumbar discs (measured from lateral radiographic views) and disc degeneration (classified from MR images) deserves attention in view of the wide, often parallel or interchanged use of both methods. The time sequence of degenerative signs and decrease of disc height is controversial. To clarify the issue, this cross-sectional study documents the relation between disc degeneration and disc height in a selected cohort. Forty-three subjects were selected at random from a cohort examined for potential disc-related disease caused by long-term lifting and carrying. From each subject a lateral radiographic view of the lumbar spine as well as findings from an MR investigation of (in most cases) levels T12/L1 to L5/S1 were available; thus, n = 237 lumbar discs were available for measurement and classification. Disc height was measured from the radiographic views with a new protocol compensating for image distortion and permitting comparison with normal, age- and gender-appropriate disc height. Degeneration as well as disc height were classified twice from MR images by independent observers in a blinded fashion. Disc degeneration classified from MR images is not related to a measurable disc height loss in the first stage of degeneration, whereas progressive degeneration goes along with progressive loss of disc height, though with considerable interindividual variation. Loss of disc height classified from MR images is on average compatible with loss of disc height measured from radiographs. In individual discs, however, classification of height loss from MR images is imprecise. The first sign of disc degeneration (a moderate loss of nucleus signal) precedes disc height decrease. As degeneration progresses, disc height decreases. Disc height decrease and progress of degeneration, however, appear to be only loosely correlated. (orig.)

  8. PR/VI Geoid Heights (GEOID96)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This 2' geoid height grid for Puerto Rico and the Virgin Islands is distributed as a GEOID96 model. The computation used 26,000 terrestrial and marine gravity data...

  9. Principal Hawaiian Islands Geoid Heights (GEOID96)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This 2' geoid height grid for the Principal Hawaiian Islands is distributed as a GEOID96 model. The computation used 61,000 terrestrial and marine gravity data held...

  10. Height as a basis for interpersonal attraction.

    Science.gov (United States)

    Hensley, W E

    1994-01-01

    Beginning with the observation of a male-taller basis in date/mate selection, this study investigated a complementary vs. a step function in choosing a dating partner. In addition, the relative advantages or disadvantages of height were examined for both genders in the dating marketplace. Our sample of college students (N = 594) indicated that while we may use a complementary standard in hypothetical date selection, the actual height of a chosen person is more likely to be made on a step function. Second, there appears to be no dating consequences for a female in a height-related sense, but taller males do enjoy a noticeable dating advantage. Finally, there appears to be a "ceiling effect" demonstrated here for the first time; the height advantage for a male seems to diminish when he is taller than six feet. Suggestions are offered which integrate the present findings into past research.

  11. U.S. Geoid Heights (GEOID96)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This 2' geoid height grid for the conterminous United States is the GEOID96 model. The computation used about 1.8 million terrestrial and marine gravity data held in...

  12. Negation of the Self in Wuthering Heights

    Institute of Scientific and Technical Information of China (English)

    李敏

    2015-01-01

    Emily Bronte created one of the greatest novels in19th British literary history---Wuthering Heights.Through this works,the writers tries to severely criticize the feature in western civilization:negation of the self.

  13. Negation of the Self in Wuthering Heights

    Institute of Scientific and Technical Information of China (English)

    李敏

    2015-01-01

    Emily Bronte created one of the greatest novels in 19th British literary history---Wuthering Heights.Through this works,the writers tries to severely criticize the feature in western civilization: negation of the self.

  14. Challenges in Defining Tsunami Wave Heights

    Science.gov (United States)

    Dunbar, Paula; Mungov, George; Sweeney, Aaron; Stroker, Kelly; Arcos, Nicolas

    2017-08-01

    The National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI) and co-located World Data Service for Geophysics maintain the global tsunami archive consisting of the historical tsunami database, imagery, and raw and processed water level data. The historical tsunami database incorporates, where available, maximum wave heights for each coastal tide gauge and deep-ocean buoy that recorded a tsunami signal. These data are important because they are used for tsunami hazard assessment, model calibration, validation, and forecast and warning. There have been ongoing discussions in the tsunami community about the correct way to measure and report these wave heights. It is important to understand how these measurements might vary depending on how the data were processed and the definition of maximum wave height. On September 16, 2015, an 8.3 M w earthquake located 48 km west of Illapel, Chile generated a tsunami that was observed all over the Pacific region. We processed the time-series water level data for 57 coastal tide gauges that recorded this tsunami and compared the maximum wave heights determined from different definitions. We also compared the maximum wave heights from the NCEI-processed data with the heights reported by the NOAA Tsunami Warning Centers. We found that in the near field different methods of determining the maximum tsunami wave heights could result in large differences due to possible instrumental clipping. We also found that the maximum peak is usually larger than the maximum amplitude (½ peak-to-trough), but the differences for the majority of the stations were definition (maximum peak or amplitude) would have validated the forecasts issued by the NOAA Tsunami Warning Centers. Since there is currently only one field in the NCEI historical tsunami database to store the maximum tsunami wave height for each tide gauge and deep-ocean buoy, NCEI will consider adding an additional field for the maximum

  15. [Fear of Heights in Primary School Children].

    Science.gov (United States)

    Huppert, D

    2016-03-01

    The life-time prevalence of visual height intolerance in adults is 28 percent, whereas in primary school children, as recently shown, it develops in 34 percent. Triggers and symptoms are similar in children and adults. A significant difference in visual height intolerance of prepubertal children compared to adults is the good prognosis with mostly spontaneous remission within a few years, possibly facilitated by repeated exposure to the triggering situations. © Georg Thieme Verlag KG Stuttgart · New York.

  16. Estimation of Stand Height and Forest Volume Using High Resolution Stereo Photography and Forest Type Map

    Science.gov (United States)

    Kim, K. M.

    2016-06-01

    Traditional field methods for measuring tree heights are often too costly and time consuming. An alternative remote sensing approach is to measure tree heights from digital stereo photographs which is more practical for forest managers and less expensive than LiDAR or synthetic aperture radar. This work proposes an estimation of stand height and forest volume(m3/ha) using normalized digital surface model (nDSM) from high resolution stereo photography (25cm resolution) and forest type map. The study area was located in Mt. Maehwa model forest in Hong Chun-Gun, South Korea. The forest type map has four attributes such as major species, age class, DBH class and crown density class by stand. Overlapping aerial photos were taken in September 2013 and digital surface model (DSM) was created by photogrammetric methods(aerial triangulation, digital image matching). Then, digital terrain model (DTM) was created by filtering DSM and subtracted DTM from DSM pixel by pixel, resulting in nDSM which represents object heights (buildings, trees, etc.). Two independent variables from nDSM were used to estimate forest stand volume: crown density (%) and stand height (m). First, crown density was calculated using canopy segmentation method considering live crown ratio. Next, stand height was produced by averaging individual tree heights in a stand using Esri's ArcGIS and the USDA Forest Service's FUSION software. Finally, stand volume was estimated and mapped using aerial photo stand volume equations by species which have two independent variables, crown density and stand height. South Korea has a historical imagery archive which can show forest change in 40 years of successful forest rehabilitation. For a future study, forest volume change map (1970s-present) will be produced using this stand volume estimation method and a historical imagery archive.

  17. Determination of coronal temperatures from electron density profiles

    CERN Document Server

    Lemaire, J F

    2011-01-01

    The most popular method for determining coronal temperatures is the scale-height-method (shm). It is based on electron density profiles inferred from White Light (WL) brightness measurements of the corona during solar eclipses. This method has been applied to several published coronal electron density models. The calculated temperature distributions reach a maximum at r > 1.3 RS, and therefore do not satisfy one of the conditions for applying the shm method. Another method is the hydrostatic equilibrium method (hst), which enables coronal temperature distributions to be determined, providing solutions to the hydrostatic equilibrium equation. The temperature maximas using the hst method are almost equal to those obtained using the shm method, but the temperature peak is always at significantly lower altitude when the hst-method is used than when the shm-method is used. A third and more recently developed method, dyn, can be used for the same published electron density profiles. The temperature distributions ob...

  18. Development and Evaluation of Models for the Relationship between Tree Height and Diameter at Breast Height for Chinese-Fir Plantations in Subtropical China.

    Science.gov (United States)

    Li, Yan-qiong; Deng, Xiang-wen; Huang, Zhi-hong; Xiang, Wen-hua; Yan, Wen-de; Lei, Pi-feng; Zhou, Xiao-lu; Peng, Chang-hui

    2015-01-01

    Tree diameter at breast height (dbh) and height are the most important variables used in forest inventory and management as well as forest carbon-stock estimation. In order to identify the key stand variables that influence the tree height-dbh relationship and to develop and validate a suit of models for predicting tree height, data from 5961 tree samples aged from 6 years to 53 years and collected from 80 Chinese-fir plantation plots were used to fit 39 models, including 33 nonlinear models and 6 linear models, were developed and evaluated into two groups. The results showed that composite models performed better in height estimate than one-independent-variable models. Nonlinear composite Model 34 and linear composite Model 6 were recommended for predicting tree height in Chinese fir plantations with a dbh range between 4 cm and 40 cm when the dbh data for each tree and the quadratic mean dbh of the stand (Dq) and mean height of the stand (Hm) were available. Moreover, Hm could be estimated by using the formula Hm = 11.707 × l n(Dq)-18.032. Clearly, Dq was the primary stand variable that influenced the height-dbh relationship. The parameters of the models varied according to stand age and site. The inappropriate application of provincial or regional height-dbh models for predicting small tree height at local scale may result in larger uncertainties. The method and the recommended models developed in this study were statistically reliable for applications in growth and yield estimation for even-aged Chinese-fir plantation in Huitong and Changsha. The models could be extended to other regions and to other tree species only after verification in subtropical China.

  19. Love and fear of heights: the pathophysiology and psychology of height imbalance.

    Science.gov (United States)

    Salassa, John R; Zapala, David A

    2009-01-01

    Individual psychological responses to heights vary on a continuum from acrophobia to height intolerance, height tolerance, and height enjoyment. This paper reviews the English literature and summarizes the physiologic and psychological factors that generate different responses to heights while standing still in a static or motionless environment. Perceptual cues to height arise from vision. Normal postural sway of 2 cm for peripheral objects within 3 m increases as eye-object distance increases. Postural sway >10 cm can result in a fall. A minimum of 20 minutes of peripheral retinal arc is required to detect motion. Trigonometry dictates that a 20-minute peripheral retinal arch can no longer be achieved in a standing position at an eye-object distance of >20 m. At this distance, visual cues conflict with somatosensory and vestibular inputs, resulting in variable degrees of imbalance. Co-occurring deficits in the visual, vestibular, and somatosensory systems can significantly increase height imbalance. An individual's psychological makeup, influenced by learned and genetic factors, can influence reactions to height imbalance. Enhancing peripheral vision and vestibular, proprioceptive, and haptic functions may improve height imbalance. Psychotherapy may improve the troubling subjective sensations to heights.

  20. Social inequalities in height: persisting differences today depend upon height of the parents.

    Directory of Open Access Journals (Sweden)

    Bruna Galobardes

    Full Text Available Substantial increases in height have occurred concurrently with economic development in most populations during the last century. In high-income countries, environmental exposures that can limit genetic growth potential appear to have lessened, and variation in height by socioeconomic position may have diminished. The objective of this study is to investigate inequalities in height in a cohort of children born in the early 1990s in England, and to evaluate which factors might explain any identified inequalities.12,830 children from The Avon Longitudinal Study of Parents and Children (ALSPAC, a population based cohort from birth to about 11.5 years of age, were used in this analysis. Gender- and age-specific z-scores of height at different ages were used as outcome variables. Multilevel models were used to take into account the repeated measures of height and to analyze gender- and age-specific relative changes in height from birth to 11.5 years. Maternal education was the main exposure variable used to examine socioeconomic inequalities. The roles of parental and family characteristics in explaining any observed differences between maternal education and child height were investigated. Children whose mothers had the highest education compared to those with none or a basic level of education, were 0.39 cm longer at birth (95% CI: 0.30 to 0.48. These differences persisted and at 11.5 years the height difference was 1.4 cm (95% CI: 1.07 to 1.74. Several other factors were related to offspring height, but few changed the relationship with maternal education. The one exception was mid-parental height, which fully accounted for the maternal educational differences in offspring height.In a cohort of children born in the 1990s, mothers with higher education gave birth to taller boys and girls. Although height differences were small they persisted throughout childhood. Maternal and paternal height fully explained these differences.

  1. Evaluation of proper height for squatting stool.

    Science.gov (United States)

    Jung, Hwa S; Jung, Hyung-Shik

    2008-05-01

    Many jobs and activities in people's daily lives have them in squatting postures. Jobs such as housekeeping, farming and welding require various squatting activities. It is speculated that prolonged squatting without any type of supporting stool would gradually and eventually impose musculoskeletal injuries on workers. This study aims to examine the proper height of the stool according to the position of working materials for the squatting worker. A total of 40 male and female college students and 10 female farmers participated in the experiment to find the proper stool height. Student participants were asked to sit and work in three different positions: floor level of 50 mm; ankle level of 200 mm; and knee level of 400 mm. They were then provided with stools of various heights and asked to maintain a squatting work posture. For each working position, they were asked to write down their thoughts on a preferred stool height. A Likert summated rating method as well as pairwise ranking test was applied to evaluate user preference for provided stools under conditions of different working positions. Under a similar experimental procedure, female farmers were asked to indicate their body part discomfort (BPD) on a body chart before and after performing the work. Statistical analysis showed that comparable results were found from both evaluation measures. When working position is below 50 mm, the proper stool height is 100 or should not be higher than 150 mm. When working position is 200 mm, the proper stool height is 150 mm. When working position is 400 mm, the proper stool height is 200 mm. Thus, it is strongly recommended to use proper height of stools with corresponding working position. Moreover, a wearable chair prototype was designed so that workers in a squatting posture do not have to carry and move the stool from one place to another. This stool should ultimately help to relieve physical stress and hence promote the health of squatting workers. This study sought

  2. Prediction of height from knee height in children with cerebral palsy and non-disabled children.

    Science.gov (United States)

    Bell, Kristie L; Davies, Peter S W

    2006-01-01

    Measurement of height or length is essential in the assessment of nutritional status. In some conditions, for example cerebral palsy (CP), such measurements may be difficult or impossible. Proxy measurements such as knee height have been used to predict height in such cases. We have evaluated two equations in the literature that predict stature from knee height in a group of 17 children with CP and 20 non-disabled children. The two equations performed well on average in the non-disabled children, with the mean predicted height being within 1% of the mean measured height. Nevertheless, the limits of agreement were relatively large. This was also the case for the children with CP. Thus the equations may be accurate at the group level; however they may lead to unacceptable error at the individual level..

  3. Rational cutting height for large cutting height fully mechanized top-coal caving

    Institute of Scientific and Technical Information of China (English)

    Huang Bingxiang; Li Hongtao; Liu Changyou; Xing Shijun; Xue Weichao

    2011-01-01

    Large cutting height fully mechanized top-coal caving is a new mining method that improves recovery ratio and single-pass production.It also allows safe and efficient mining.A rational cutting height is one key parameter of this technique.Numerical simulation and a granular-media model experiment were used to analyze the effect of cutting height on the rock pressure of a fully mechanized top-coal caving work face.The recovery ratio was also studied.As the cutting height increases the top-coal thickness is reduced.Changing the ratio of cutting to drawing height intensifies the face pressure and the top-coal shattering.A maximum cutting height exists under a given set of conditions due to issues with surrounding rock-mass control.An increase in cutting height makes the top-coal cave better and the recovery ratio when drawing top-coal is then improved.A method of adjusting the face rock pressure is presented.Changing the cutting to drawing height ratio is the technique used to control face rock pressure.The recovery ratio when cutting coal exceeds that when caving top-coal so the face recovery ratio may be improved by over sizing the cutting height and increasing the top-coal drawing ratio.An optimum ratio of cutting to drawing height exists that maximizes the face recovery ratio.A rational cutting height is determined by comprehensively considering the surrounding rock-mass control and the recovery ratio.At the same time increasing the cutting height can improve single pass mining during fully mechanized top-coal caving.

  4. The difference between the Weil height and the canonical height on elliptic curves

    Science.gov (United States)

    Silverman, Joseph H.

    1990-10-01

    Estimates for the difference of the Weil height and the canonical height of points on elliptic curves are used for many purposes, both theoretical and computational. In this note we give an explicit estimate for this difference in terms of the j-invariant and discriminant of the elliptic curve. The method of proof, suggested by Serge Lang, is to use the decomposition of the canonical height into a sum of local heights. We illustrate one use for our estimate by computing generators for the Mordell-Weil group in three examples.

  5. Longitudinal Relationship between Axial Length and Height in Chinese Children:Guangzhou Twin Eye Study

    Institute of Scientific and Technical Information of China (English)

    Decai Wang; Chen Zhao; Shengsong Huang; Wenyong Huang; Mingguang He

    2015-01-01

    Purpose:.To understand the growth model of axial length (AL) and height, and to explore the relationship between the two with the passage of time. Methods:.We followed twins in the Guangzhou Twin Eye Study for five years..The AL of both eyes was measured by partial coherence interferometry, and height was measured by a standard scale during each visit..A multivariate multilevel mixed model was adopted for data analysis. Results:.A total of 1217 children were included in the study. Both AL and height increased, but the rate of growth slowed down with age..The mitigation rate of height growth was -0.34 cm/year;.while that of AL growth was -0.01 mm/year. AL was positively related to height,.with a relevant coefficient of R=0.22 (Cov [height intercept, AL intercept] =1.56, 95%CI=1.14 to 1.99). The growth rates of AL and height were al-so positively related, with a relevant coefficient of R=0.18 (Cov [height slope, AL slope] =0.03, 95%CI=0.01 to 0.05). However, taller children had slower rates of height increases, with a relevant coefficient of R=-0.12 (Cov[height intercept, height slope]=-1.33,95%CI=-2.25 to-0.42); but had faster AL growth,.with a relevant coefficient of R=(Cov [height intercept, AL slope] =0.02, 95%CI=-0.05 to 0.08, R=0.02). AL and its growth rate were positively related to each other, with a relevant coefficient of R=(Cov [AL intercept,.AL slope]=0.04, 95%CI=0.03 to 0.05, R=0.3); while the growth rates of AL and height were negatively related to each other, with a relevant coefficient of R=(Cov[AL intercept, height slope]=--0.03 95%CI=-0.16 to 0.1, R=-0.02). Conclusion:.The increase in children's AL is relevant to their height increases..The faster their height increases,.the faster their AL increases.

  6. The influence of recent climate change on tree height growth differs with species and spatial environment.

    Science.gov (United States)

    Messaoud, Yassine; Chen, Han Y H

    2011-02-16

    Tree growth has been reported to increase in response to recent global climate change in controlled and semi-controlled experiments, but few studies have reported response of tree growth to increased temperature and atmospheric carbon dioxide (CO₂) concentration in natural environments. This study addresses how recent global climate change has affected height growth of trembling aspen (Populus tremuloides Michx) and black spruce (Picea mariana Mill B.S.) in their natural environments. We sampled 145 stands dominated by aspen and 82 dominated by spruce over the entire range of their distributions in British Columbia, Canada. These stands were established naturally after fire between the 19th and 20th centuries. Height growth was quantified as total heights of sampled dominant and co-dominant trees at breast-height age of 50 years. We assessed the relationships between 50-year height growth and environmental factors at both spatial and temporal scales. We also tested whether the tree growth associated with global climate change differed with spatial environment (latitude, longitude and elevation). As expected, height growth of both species was positively related to temperature variables at the regional scale and with soil moisture and nutrient availability at the local scale. While height growth of trembling aspen was not significantly related to any of the temporal variables we examined, that of black spruce increased significantly with stand establishment date, the anomaly of the average maximum summer temperature between May-August, and atmospheric CO₂ concentration, but not with the Palmer Drought Severity Index. Furthermore, the increase of spruce height growth associated with recent climate change was higher in the western than in eastern part of British Columbia. This study demonstrates that the response of height growth to recent climate change, i.e., increasing temperature and atmospheric CO₂ concentration, did not only differ with tree species, but

  7. The influence of recent climate change on tree height growth differs with species and spatial environment.

    Directory of Open Access Journals (Sweden)

    Yassine Messaoud

    Full Text Available Tree growth has been reported to increase in response to recent global climate change in controlled and semi-controlled experiments, but few studies have reported response of tree growth to increased temperature and atmospheric carbon dioxide (CO₂ concentration in natural environments. This study addresses how recent global climate change has affected height growth of trembling aspen (Populus tremuloides Michx and black spruce (Picea mariana Mill B.S. in their natural environments. We sampled 145 stands dominated by aspen and 82 dominated by spruce over the entire range of their distributions in British Columbia, Canada. These stands were established naturally after fire between the 19th and 20th centuries. Height growth was quantified as total heights of sampled dominant and co-dominant trees at breast-height age of 50 years. We assessed the relationships between 50-year height growth and environmental factors at both spatial and temporal scales. We also tested whether the tree growth associated with global climate change differed with spatial environment (latitude, longitude and elevation. As expected, height growth of both species was positively related to temperature variables at the regional scale and with soil moisture and nutrient availability at the local scale. While height growth of trembling aspen was not significantly related to any of the temporal variables we examined, that of black spruce increased significantly with stand establishment date, the anomaly of the average maximum summer temperature between May-August, and atmospheric CO₂ concentration, but not with the Palmer Drought Severity Index. Furthermore, the increase of spruce height growth associated with recent climate change was higher in the western than in eastern part of British Columbia. This study demonstrates that the response of height growth to recent climate change, i.e., increasing temperature and atmospheric CO₂ concentration, did not only differ with tree

  8. Experiences of ZAMG on mixing height determination

    Energy Technology Data Exchange (ETDEWEB)

    Piringer, M. [Zentralanstalt fuer Meteorologie und Geodynamik, ZAMG, Vienna (Austria)

    1997-10-01

    Temperature inversions in the boundary layer occur quite often, esp. in mountainous terrain by which Austria is covered to a large extent, and can lead to enhanced pollution at the surface because the air volume available for dilution is then vertically limited. The Department of Environmental Meteorology of ZAMG therefore set up several field programs in the past to study such conditions at a variety of sites in Austria, using tethersondes and Sodars. Early investigations aimed at comparing Sodar echo profiles to the tethersonde temperature profiles to derive mixing heights from the Sodar echo structure. More recently, evolving from KONGEX, the `convective boundary layer experiment`, mixing heights calculated for Vienna by the OML model were compared to those derived from radiosonde and tethersonde potential temperature profiles. Results of these investigations will be presented, focussing on the problems when using the different methods. New efforts to derive mixing heights from data were also undertaken and are discussed separately. (au)

  9. Height, Relationship Satisfaction, Jealousy, and Mate Retention

    Directory of Open Access Journals (Sweden)

    Gayle Brewer

    2009-07-01

    Full Text Available Male height is associated with high mate value. In particular, tall men are perceived as more attractive, dominant and of a higher status than shorter rivals, resulting in a greater lifetime reproductive success. Female infidelity and relationship dissolution may therefore present a greater risk to short men. It was predicted that tall men would report greater relationship satisfaction and lower jealousy and mate retention behavior than short men. Ninety eight heterosexual men in a current romantic relationship completed a questionnaire. Both linear and quadratic relationships were found between male height and relationship satisfaction, cognitive and behavioral jealousy. Tall men reported greater relationship satisfaction and lower levels of cognitive or behavioral jealousy than short men. In addition, linear and quadratic relationships were found between male height and a number of mate retention behaviors. Tall and short men engaged in different mate retention behaviors. These findings are consistent with previous research conducted in this area detailing the greater attractiveness of tall men.

  10. Weak Environmental Controls of Tropical Forest Canopy Height in the Guiana Shield

    Directory of Open Access Journals (Sweden)

    Youven Goulamoussène

    2016-09-01

    Full Text Available Canopy height is a key variable in tropical forest functioning and for regional carbon inventories. We investigate the spatial structure of the canopy height of a tropical forest, its relationship with environmental physical covariates, and the implication for tropical forest height variation mapping. Making use of high-resolution maps of LiDAR-derived Digital Canopy Model (DCM and environmental covariates from a Digital Elevation Model (DEM acquired over 30,000 ha of tropical forest in French Guiana, we first show that forest canopy height is spatially correlated up to 2500 m. Forest canopy height is significantly associated with environmental variables, but the degree of correlation varies strongly with pixel resolution. On the whole, bottomland forests generally have lower canopy heights than hillslope or hilltop forests. However, this global picture is very noisy at local scale likely because of the endogenous gap-phase forest dynamic processes. Forest canopy height has been predictively mapped across a pixel resolution going from 6 m to 384 m mimicking a low resolution case of 3 points·km − 2 . Results of canopy height mapping indicated that the error for spatial model with environment effects decrease from 8.7 m to 0.91 m, depending of the pixel resolution. Results suggest that, outside the calibration plots, the contribution of environment in shaping the global canopy height distribution is quite limited. This prevents accurate canopy height mapping based only on environmental information, and suggests that precise canopy height maps, for local management purposes, can only be obtained with direct LiDAR monitoring.

  11. Correlation among body height, intelligence, and brain gray matter volume in healthy children.

    Science.gov (United States)

    Taki, Yasuyuki; Hashizume, Hiroshi; Sassa, Yuko; Takeuchi, Hikaru; Asano, Michiko; Asano, Kohei; Kotozaki, Yuka; Nouchi, Rui; Wu, Kai; Fukuda, Hiroshi; Kawashima, Ryuta

    2012-01-16

    A significant positive correlation between height and intelligence has been demonstrated in children. Additionally, intelligence has been associated with the volume of gray matter in the brains of children. Based on these correlations, we analyzed the correlation among height, full-scale intelligence quotient (IQ) and gray matter volume applying voxel-based morphometry using data from the brain magnetic resonance images of 160 healthy children aged 5-18 years of age. As a result, body height was significantly positively correlated with brain gray matter volume. Additionally, the regional gray matter volume of several regions such as the bilateral prefrontal cortices, temporoparietal region, and cerebellum was significantly positively correlated with body height and that the gray matter volume of several of these regions was also significantly positively correlated with full-scale intelligence quotient (IQ) scores after adjusting for age, sex, and socioeconomic status. Our results demonstrate that gray and white matter volume may mediate the correlation between body height and intelligence in healthy children. Additionally, the correlations among gray and white matter volume, height, and intelligence may be at least partially explained by the effect of insulin-like growth factor-1 and growth hormones. Given the importance of the effect of environmental factors, especially nutrition, on height, IQ, and gray matter volume, the present results stress the importance of nutrition during childhood for the healthy maturation of body and brain. Copyright © 2011 Elsevier Inc. All rights reserved.

  12. Evidence of inbreeding depression on human height.

    Directory of Open Access Journals (Sweden)

    Ruth McQuillan

    Full Text Available Stature is a classical and highly heritable complex trait, with 80%-90% of variation explained by genetic factors. In recent years, genome-wide association studies (GWAS have successfully identified many common additive variants influencing human height; however, little attention has been given to the potential role of recessive genetic effects. Here, we investigated genome-wide recessive effects by an analysis of inbreeding depression on adult height in over 35,000 people from 21 different population samples. We found a highly significant inverse association between height and genome-wide homozygosity, equivalent to a height reduction of up to 3 cm in the offspring of first cousins compared with the offspring of unrelated individuals, an effect which remained after controlling for the effects of socio-economic status, an important confounder (χ(2 = 83.89, df = 1; p = 5.2 × 10(-20. There was, however, a high degree of heterogeneity among populations: whereas the direction of the effect was consistent across most population samples, the effect size differed significantly among populations. It is likely that this reflects true biological heterogeneity: whether or not an effect can be observed will depend on both the variance in homozygosity in the population and the chance inheritance of individual recessive genotypes. These results predict that multiple, rare, recessive variants influence human height. Although this exploratory work focuses on height alone, the methodology developed is generally applicable to heritable quantitative traits (QT, paving the way for an investigation into inbreeding effects, and therefore genetic architecture, on a range of QT of biomedical importance.

  13. Adult height, dietary patterns, and healthy aging.

    Science.gov (United States)

    Ma, Wenjie; Hagan, Kaitlin A; Heianza, Yoriko; Sun, Qi; Rimm, Eric B; Qi, Lu

    2017-08-01

    Background: Adult height has shown directionally diverse associations with several age-related disorders, including cardiovascular disease, cancer, decline in cognitive function, and mortality.Objective: We investigated the associations of adult height with healthy aging measured by a full spectrum of health outcomes, including incidence of chronic diseases, memory, physical functioning, and mental health, among populations who have survived to older age, and whether lifestyle factors modified such relations.Design: We included 52,135 women (mean age: 44.2 y) from the Nurses' Health Study without chronic diseases in 1980 and whose health status was available in 2012. Healthy aging was defined as being free of 11 major chronic diseases and having no reported impairment of subjective memory, physical impairment, or mental health limitations.Results: Of all eligible study participants, 6877 (13.2%) were classified as healthy agers. After adjustment for demographic and lifestyle factors, we observed an 8% (95% CI: 6%, 11%) decrease in the odds of healthy aging per SD (0.062 m) increase in height. Compared with the lowest category of height (≤1.57 m), the OR of achieving healthy aging in the highest category (≥1.70 m) was 0.80 (95% CI: 0.73, 0.87; P-trend aging (P-interaction = 0.005), and among the individual dietary factors characterizing the prudent dietary pattern, fruit and vegetable intake showed the strongest effect modification (P-interaction = 0.01). The association of greater height with reduced odds of healthy aging appeared to be more evident among women with higher adherence to the prudent dietary pattern rich in vegetable and fruit intake.Conclusions: Greater height was associated with a modest decrease in the likelihood of healthy aging. A prudent diet rich in fruit and vegetables might modify the relation. © 2017 American Society for Nutrition.

  14. An applied model for the height of the daytime mixed layer and the entrainment zone

    DEFF Research Database (Denmark)

    Batchvarova, E.; Gryning, Sven-Erik

    1994-01-01

    -layer height: friction velocity, kinematic heat flux near the ground and potential temperature gradient in the free atmosphere above the entrainment zone. When information is available on the horizontal divergence of the large-scale flow field, the model also takes into account the effect of subsidence......A model is presented for the height of the mixed layer and the depth of the entrainment zone under near-neutral and unstable atmospheric conditions. It is based on the zero-order mixed layer height model of Batchvarova and Gryning (1991) and the parameterization of the entrainment zone depth...

  15. The mental space of pitch height.

    Science.gov (United States)

    Rusconi, Elena; Kwan, Bonnie; Giordano, Bruno; Umiltà, Carlo; Butterworth, Brian

    2005-12-01

    Through stimulus-response compatibility we tested whether sound frequency (pitch height) elicits a mental spatial representation. Musically untrained and, mostly, trained participants were shown a stimulus-response compatibility effect (Spatial-Musical Association of Response Codes or SMARC effect). When response alternatives were either vertically or horizontally aligned, performance was better when the lower (or leftward) button had to be pressed in response to a low sound and the upper (or rightward) button had to be pressed in response to a high sound, even when pitch height was irrelevant to the task.

  16. Height Matters: Citizen Science with the ICESat-2 Satellite

    Science.gov (United States)

    Casasanto, V.; Campbell, B.; Neumann, T.; Brunt, K. M.

    2016-12-01

    The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) to be launched in late 2017, will measure the height of Earth from space using lasers, collecting the most precise and detailed account yet of our planet's elevation. The mission will allow scientists to investigate how global warming is changing the planet's icy polar regions and to take stock of Earth's vegetation. ICESat-2's emphasis on polar ice, as well as its unique measurement approach, will provide an intriguing and accessible focus for the mission's education and outreach programs. Sea ice and land ice are areas that have experienced significant change in recent years. It is key to communicate why we are measuring these areas and their importance. ICESat-2 science data will provide much-needed answers to climate change questions such as, "Is the ice really melting in the polar regions?" and "What does studying Earth's frozen regions tell us about our changing climate?" Since the ICESat-2 satellite will be measuring the height of our planet, vegetation and tree height are also of vital interest. With this data, we can see small to large scale changes in Earth's environment. The ICESat-2 Mission is partnering with The GLOBE Program to emphasize these measurements in a hands-on way. Through modified protocols utilizing a hand-held clinometer and GPS, students and citizen scientists in both urban and non-urban areas will be able to measure the heights of trees and buildings to assist NASA in validating the ICESat-2 satellite data.

  17. Collision geometry scaling of Au+Au pseudorapidity density from sqrt(s_NN) = 19.6 to 200 GeV

    CERN Document Server

    Back, B B; Ballintijn, M; Barton, D S; Betts, R R; Bickley, A A; Bindel, R; Budzanowski, A; Busza, W; Carroll, A; Decowski, M P; García, E; George, N; Gulbrandsen, K H; Gushue, S; Halliwell, C; Hamblen, J; Heintzelman, G A; Henderson, C; Hofman, D J; Hollis, R S; Holynski, R; Holzman, B; Iordanova, A; Johnson, E; Kane, J L; Katzy, J; Khan, N; Kucewicz, W; Kulinich, P; Kuo, C M; Lin, W T; Manly, S; McLeod, D; Mignerey, A C; Nouicer, R; Olszewski, A; Pak, R; Park, I C; Pernegger, H; Reed, C; Remsberg, L P; Reuter, M; Roland, C; Roland, G; Rosenberg, L J; Sagerer, J; Sarin, P; Sawicki, P; Skulski, W; Steinberg, P; Stephans, G S F; Sukhanov, A; Tonjes, M B; Tang, J L; Trzupek, A; Vale, C; van Nieuwenhuizen, G J; Verdier, R; Wolfs, F L H; Wosiek, B; Wozniak, K; Wuosmaa, A H; Wyslouch, B

    2004-01-01

    The centrality dependence of the midrapidity charged particle multiplicity in Au+Au collisions at sqrt(s_NN) = 19.6 and 200 GeV is presented. Within a simple model, the fraction of hard (scaling with number of binary collisions) to soft (scaling with number of participant pairs) interactions is consistent with a value of x = 0.13 +/- 0.01(stat) +/- 0.05(syst) at both energies. The experimental results at both energies, scaled by inelastic p(pbar)+p collision data, agree within systematic errors. The ratio of the data was found not to depend on centrality over the studied range and yields a simple linear scale factor of R_(200/19.6) = 2.03 +/- 0.02(stat) +/- 0.05(syst).

  18. Fear of heights and mild visual height intolerance independent of alcohol consumption.

    Science.gov (United States)

    Huppert, Doreen; Grill, Eva; Kapfhammer, Hans-Peter; Brandt, Thomas

    2013-09-01

    Background Visual height intolerance occurs when a visual stimulus causes apprehension of losing balance and falling from some height. Affecting one-third of the population, it has a broad spectrum of symptoms, ranging from minor distress to fear of heights, which is defined as a specific phobia. Specific phobias are associated with higher alcohol consumption. This has not been specifically shown for susceptibility to the more general visual height intolerance. Methods Representative case-control study nested within a population-based cross-sectional telephone survey to assess epidemiologically 1253 individuals ≥14 years, using a questionnaire on sociodemographic data, typical symptoms, precipitating visual stimuli, and alcohol drinking patterns (overall frequency of alcohol consumption, the daily quantities, and the motives). Results Individuals susceptible or nonsusceptible to visual height intolerance showed no significant differences in drinking patterns. The daily average alcohol consumption was slightly higher in persons susceptible to visual height intolerance (4.1 g/day vs. 3.7 g/day). Of those consuming alcohol, cases and controls reported on average consuming 2.3 glasses per day. The prevalence of visual height intolerance was insignificantly higher in the small minority of those drinking 2-3 times per week versus teetotalers. Conclusions Our study does not provide evidence that visual height intolerance - contrary to various specific phobias - is significantly associated with individual alcohol consumption patterns.

  19. A large-scale population-based study of the association of vitamin D receptor gene polymorphisms with bone mineral density.

    NARCIS (Netherlands)

    P.L.A. van Dalen; C.M. van Duijn (Cock); J.C. Birkenhäger (Jan); J.P.T.M. van Leeuwen (Hans); H.A.P. Pols (Huib); A.G. Uitterlinden (André); A. Hofman (Albert)

    1996-01-01

    textabstractConflicting results have been reported on the association between restriction fragment length polymorphisms (RFLPs) at the vitamin D receptor (VDR) gene locus (i.e., for BsmI, ApaI, and TaqI) and bone mineral density (BMD). We analyzed this association in a large population-based sample

  20. Factors influencing the local scale colonisation and change in density of a widespread invasive plant species, Lantana camara, in South India

    Directory of Open Access Journals (Sweden)

    Bharath Sundaram

    2015-04-01

    Full Text Available Identifying factors that underlie invasive species colonisation and change in density could provide valuable insights into the mechanisms of biological invasions and for invasive species management. We examined a suite of factors potentially influencing the landscape-level invasion of Lantana camara L., one of the most ubiquitous invasive species in South Asia. These factors included disturbance factors like forest fires, historical habitat modification, and edge effects, in addition to factors like propagule pressure and habitat suitability. We examined the relative importance of these factors on the colonisation and change in density of L. camara in the Biligiri Rangaswamy Temple Tiger Reserve, Western Ghats, India. We used extensive (1997–2008 datasets tracking the presence and abundance of L. camara and combined these with corresponding data on disturbances, propagule pressure, and habitat suitability. We used an information-theoretic model selection approach to determine the relative importance of each factor on the colonisation and change in density of L. camara. Colonisation was mainly a function of proximity to already established populations (i.e. propagule pressure, whereas increase in L. camara density appeared to be constrained by high fire frequency. Research and management efforts need to recognize the multi-dimensional nature of mechanisms underlying L. camara’s success during different invasion phases when strategizing interventions to mitigate its effects.

  1. Estimating Aerodynamic Parameters of Urban-Like Surfaces with Heterogeneous Building Heights

    Science.gov (United States)

    Millward-Hopkins, J. T.; Tomlin, A. S.; Ma, L.; Ingham, D.; Pourkashanian, M.

    2011-12-01

    There are many geometrical factors than can influence the aerodynamic parameters of urban surfaces and hence the vertical wind profiles found above. The knowledge of these parameters has applications in numerous fields, such as dispersion modelling, wind loading calculations, and estimating the wind energy resource at urban locations. Using quasi-empirical modelling, we estimate the dependence of the aerodynamic roughness length and zero-plane displacement for idealized urban surfaces, on the two most significant geometrical characteristics; surface area density and building height variability. A validation of the spatially-averaged, logarithmic wind profiles predicted by the model is carried out, via comparisons with available wind-tunnel and numerical data for arrays of square based blocks of uniform and heterogeneous heights. The model predicts two important properties of the aerodynamic parameters of surfaces of heterogeneous heights that have been suggested by experiments. Firstly, the zero-plane displacement of a heterogeneous array can exceed the surface mean building height significantly. Secondly, the characteristic peak in roughness length with respect to surface area density becomes much softer for heterogeneous arrays compared to uniform arrays, since a variation in building height can prevent a skimming flow regime from occurring. Overall the simple model performs well against available experimental data and may offer more accurate estimates of surface aerodynamic parameters for complex urban surfaces compared to models that do not include height variability.

  2. Aircraft height estimation using 2-D radar

    CSIR Research Space (South Africa)

    Hakl, H

    2010-01-01

    Full Text Available A method to infer height information from an aircraft tracked with a single 2-D search radar is presented. The method assumes level flight in the target aircraft and a good estimate of the speed of the aircraft. The method yields good results...

  3. Height as a Basis for Interpersonal Attraction.

    Science.gov (United States)

    Hensley, Wayne E.

    Based on the observation that taller males seem to have an advantage in date/mate selection, a study investigated the role that height plays in the choice of a partner. Subjects, 594 student volunteers from communication classes at a large Mid-Atlantic university, completed a questionnaire designed to assess such factors as respondent sex, present…

  4. Intralocus sexual conflict over human height

    NARCIS (Netherlands)

    Stulp, Gert; Kuijper, Bram; Buunk, Abraham P.; Pollet, Thomas V.; Verhulst, Simon

    2012-01-01

    Intralocus sexual conflict (IASC) occurs when a trait under selection in one sex constrains the other sex from achieving its sex-specific fitness optimum. Selection pressures on body size often differ between the sexes across many species, including humans: among men individuals of average height en

  5. Statistical analysis on extreme wave height

    Digital Repository Service at National Institute of Oceanography (India)

    Teena, N.V.; SanilKumar, V.; Sudheesh, K.; Sajeev, R.

    the distributions fitted to the GEV with annual maximum approach and GPD with peaks over threshold approach have indicated that both GEV and GPD models gave similar or comparable wave height for the study area since there is no multiple storm event in a year...

  6. Lang's Height Conjecture and Szpiro's Conjecture

    CERN Document Server

    Silverman, Joseph H

    2009-01-01

    It is known that Szpiro's conjecture, or equivalently the ABC-conjecture, implies Lang's conjecture giving a uniform lower bound for the canonical height of nontorsion points on elliptic curves. In this note we show that a significantly weaker version of Szpiro's conjecture, which we call "prime-depleted," suffices to prove Lang's conjecture.

  7. An Analysis of Personality in Wuthering Heights

    Institute of Scientific and Technical Information of China (English)

    Liu Feng

    2011-01-01

    Compared to other two sisters,Emily Bronte has a few of works,just only one novel and some poets.However,it is the novel Wuthering Heights arousing more and more critics' attention after more than 100 years since it was born.The reason that a great works

  8. The Artistic Glamour of Wuthering Heights

    Institute of Scientific and Technical Information of China (English)

    Li Wenyan

    2012-01-01

    Emily Bronte's Wuthering Heights is a classical masterpiece,known as"the most peculiar novel"in the English literature.The paper focuses on its structure and main idea,so as to reveal its thrilling artistic glamour and its artistic style.

  9. Growth hormone: health considerations beyond height gain

    Science.gov (United States)

    The therapeutic benefit of growth hormone (GH) therapy in improving height in short children is widely recognized; however, GH therapy is associated with other metabolic actions that may be of benefit in these children. Beneficial effects of GH on body composition have been documented in several dif...

  10. The Roles of Symbols in Wuthering Heights

    Institute of Scientific and Technical Information of China (English)

    孙贻红

    2015-01-01

    In Wuthering Heights, Emily Bronte portrays the love story between Catherine and Heathcliff whose sincere love is killed for their different social status and only prevails beyond the real world. The roles of symbols in revealing this theme will be traced in this article.

  11. Environmental Assessment: Disposition of Maxwell Heights Annex

    Science.gov (United States)

    2005-07-01

    Maxwell Support Division May 4, 2005 Mr. David Rabon Tribal Historic Preservation Officer Cherokee Nation of Oklahoma P.O. Box 948 Tahlequah...Oklahoma 74465 RE: Disposal of the Existing Property and Facilities of the Maxwell Heights Annex Maxwell Air Force Base, Alabama Dear Mr. Rabon , The

  12. Height, sitting height, and leg length in relation with breast cancer risk in the E3N cohort

    National Research Council Canada - National Science Library

    Fagherazzi, Guy; Vilier, Alice; Boutron-Ruault, Marie-Christine; Clavel-Chapelon, Françoise; Mesrine, Sylvie

    2012-01-01

    If height is a well-established risk factor for breast cancer, leg length and sitting height are usually considered as better candidate biomarkers of growth hormone exposure than height, respectively...

  13. Gradient-Based Optimization of Wind Farms with Different Turbine Heights: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Stanley, Andrew P. J.; Thomas, Jared; Ning, Andrew; Annoni, Jennifer; Dykes, Katherine; Fleming, Paul

    2017-05-08

    Turbine wakes reduce power production in a wind farm. Current wind farms are generally built with turbines that are all the same height, but if wind farms included turbines with different tower heights, the cost of energy (COE) may be reduced. We used gradient-based optimization to demonstrate a method to optimize wind farms with varied hub heights. Our study includes a modified version of the FLORIS wake model that accommodates three-dimensional wakes integrated with a tower structural model. Our purpose was to design a process to minimize the COE of a wind farm through layout optimization and varying turbine hub heights. Results indicate that when a farm is optimized for layout and height with two separate height groups, COE can be lowered by as much as 5%-9%, compared to a similar layout and height optimization where all the towers are the same. The COE has the best improvement in farms with high turbine density and a low wind shear exponent.

  14. Partial-reflection studies of D-region winter variability. [electron density measurements

    Science.gov (United States)

    Denny, B. W.; Bowhill, S. A.

    1973-01-01

    D-region electron densities were measured from December, 1972, to July, 1973, at Urbana, Illinois (latitude 40.2N) using the partial-reflection technique. During the winter, electron densities at altitudes of 72, 76.5, and 81 km show cyclical changes with a period of about 5 days that are highly correlated between these altitudes, suggesting that the mechanism responsible for the winter anomaly in D-region ionization applies throughout this height region. From January 13 to February 3, a pronounced wave-like variation occurred in the partial-reflection measurements, apparently associated with a major stratospheric warming that developed in that period. During the same time period, a traveling periodic variation is observed in the 10-mb height; it is highly correlated with the partial-reflection measurements. Electron density enhancements occur approximately at the same time as increases in the 10-mb height. Comparison of AL and A3 absorption measurements with electron density measurements below 82 km indicates that the winter anomaly in D-region ionization is divided into two types. Type 1, above about 82 km, extends horizontally for about 200 km while type 2, below about 82 km, extends for a horizontal scale of at least 1000 km.

  15. High cell density media for Escherichia coli are generally designed for aerobic cultivations – consequences for large-scale bioprocesses and shake flask cultures

    Directory of Open Access Journals (Sweden)

    Neubauer Peter

    2008-08-01

    Full Text Available Abstract Background For the cultivation of Escherichia coli in bioreactors trace element solutions are generally designed for optimal growth under aerobic conditions. They do normally not contain selenium and nickel. Molybdenum is only contained in few of them. These elements are part of the formate hydrogen lyase (FHL complex which is induced under anaerobic conditions. As it is generally known that oxygen limitation appears in shake flask cultures and locally in large-scale bioreactors, function of the FHL complex may influence the process behaviour. Formate has been described to accumulate in large-scale cultures and may have toxic effects on E. coli. Although the anaerobic metabolism of E. coli is well studied, reference data which estimate the impact of the FHL complex on bioprocesses of E. coli with oxygen limitation have so far not been published, but are important for a better process understanding. Results Two sets of fed-batch cultures with conditions triggering oxygen limitation and formate accumulation were performed. Permanent oxygen limitation which is typical for shake flask cultures was caused in a bioreactor by reduction of the agitation rate. Transient oxygen limitation, which has been described to eventually occur in the feed-zone of large-scale bioreactors, was mimicked in a two-compartment scale-down bioreactor consisting of a stirred tank reactor and a plug flow reactor (PFR with continuous glucose feeding into the PFR. In both models formate accumulated up to about 20 mM in the culture medium without addition of selenium, molybdenum and nickel. By addition of these trace elements the formate accumulation decreased below the level observed in well-mixed laboratory-scale cultures. Interestingly, addition of the extra trace elements caused accumulation of large amounts of lactate and reduced biomass yield in the simulator with permanent oxygen limitation, but not in the scale-down two-compartment bioreactor. Conclusion The

  16. Dispersal behavior of Tetranychus evansi and T. urticae on tomato at several spatial scales and densities: implications for integrated pest management.

    Science.gov (United States)

    Azandémè-Hounmalon, Ginette Y; Fellous, Simon; Kreiter, Serge; Fiaboe, Komi K M; Subramanian, Sevgan; Kungu, Miriam; Martin, Thibaud

    2014-01-01

    Studying distribution is necessary to understand and manage the dynamics of species with spatially structured populations. Here we studied the distribution in Tetranychus evansi and T. urticae, two mite pests of tomato, in the scope of evaluating factors that can influence the effectiveness of Integrated Pest Management strategies. We found greater positive density-dependent distribution with T. evansi than T. urticae when assayed on single, detached tomato leaves. Indeed, T. evansi distribution among leaflets increased with initial population density while it was high even at low T. urticae densities. Intensity and rate of damage to whole plants was higher with T. evansi than T. urticae. We further studied the circadian migration of T. evansi within plant. When T. evansi density was high the distribution behavior peaked between 8 am and 3 pm and between 8 pm and 3 am local time of Kenya. Over 24 h the total number of mites ascending and descending was always similar and close to the total population size. The gregarious behavior of T. evansi combined with its rapid population growth rate, may explain why few tomato plants can be severely damaged by T. evansi and how suddenly all the crop can be highly infested. However the localisation and elimination of the first infested plants damaged by T. evansi could reduce the risk of outbreaks in the entire crop. These findings suggest also that an acaricide treated net placed on the first infested plants could be very effective to control T. evansi. Moreover circadian migration would therefore accentuate the efficiency of an acaricide treated net covering the infested plants.

  17. Road density

    Data.gov (United States)

    U.S. Environmental Protection Agency — Road density is generally highly correlated with amount of developed land cover. High road densities usually indicate high levels of ecological disturbance. More...

  18. Comparison of measured and modelled mixing heights during the Borex`95 experiment

    Energy Technology Data Exchange (ETDEWEB)

    Mikkelsen, T.; Astrup, P.; Joergensen, H.E.; Ott, S. [Risoe National Lab., Roskilde (Denmark); Soerensen, J.H. [Danish Meteorological Inst., Copenhagen (Denmark); Loefstroem, P. [National Environmental Research Inst., Roskilde (Denmark)

    1997-10-01

    A real-time modelling system designed for `on-the-fly` assessment of atmospheric dispersion during accidental releases is under establishment within the framework of the European Union. It integrates real-time dispersion models for both local scale and long range transport with wind, turbulence and deposition models. As meteorological input, the system uses both on-situ measured and on-line available meteorology. The resulting real-time dispersion system is called MET-RODOS. This paper focuses on evaluation of the MET-RODOS systems build-in local scale pre-processing software for real-time determination of mixing height, - an important parameter for the local scale dispersion assessments. The paper discusses the systems local scale mixing height algorithms as well as its in-line mixing height acquisition from the DMI-HIRLAM model. Comparisons of the diurnal mixing height evolution is made with measured mixing heights from in-situ radio-sonde data during the Borex`95 field trials, and recently also with remote sensed (LIDAR) aerosol profiles measured at Risoe. (LN)

  19. Light-exposed shoots of seven coexisting deciduous species show common photosynthetic responses to tree height.

    Science.gov (United States)

    Miyata, Rie; Kohyama, Takashi S

    2016-10-01

    Functional traits of light-exposed leaves have been reported to show tree height-dependent change. However, it remains unknown how plastic response of leaf traits to tree height is linked with shoot-level carbon gain. To answer this question, we examined the photosynthetic properties of fully lit current-year shoots in crown tops with various heights for seven deciduous broad-leaved species dominated in a cool-temperate forest in northern Japan. We measured leaf mass, stomatal conductance, nitrogen content, light-saturated net photosynthetic rate (all per leaf lamina area), foliar stable carbon isotope ratio, and shoot mass allocation to leaf laminae. We employed hierarchical Bayesian models to simultaneously quantify inter-trait relationships for all species. We found that leaf and shoot traits were co-varied in association with height, and that there was no quantitative inter-specific difference in leaf- and shoot-level plastic responses to height. Nitrogen content increased and stomatal conductance decreased with height. Reflecting these antagonistic responses to height, photosynthetic rate was almost unchanged with height. Photosynthetic rate divided by stomatal conductance as a proxy of photosynthetic water use efficiency sufficiently explained the variation of foliar carbon isotope ratio. The increase in mass allocation to leaves in a shoot compensated for the height-dependent decline in photosynthetic rate per leaf lamina mass. Consequently, photosynthetic gain at the scale of current-year shoot mass was kept unchanged with tree height. We suggest that the convergent responses of shoot functional traits across species reflect common requirements for trees coexisting in a forest.

  20. Route Height Connection Across the Sea by Using the Vertical Deflections and Ellipsoidal Height Data

    Institute of Scientific and Technical Information of China (English)

    GUO Jin-yun; CHEN Yong-ning; LIU Xin; ZHONG Shi-xia; MAI Zhao-qiu

    2013-01-01

    Distance between the main land and island is so long that it is very difficult to precisely connect the height datum across the sea with the traditional method like the trigonometric leveling,or it is very expensive and takes long time to implement the height transfer with the geopotential technique.We combine the data of GPS surveying,astro-geodesy and EGM2008 to precisely connect the orthometric height across the sea with the improved astronomical leveling method in the paper.The Qiongzhou Strait is selected as the test area for the height connection over the sea.We precisely determine the geodetic latitudes,longitudes,heights and deflections of the vertical for four points on both sides across the strait.Modeled deflections of the vertical along the height connecting routes over the sea are determined with EGM2008 model based on the geodetic positions and heights of the sea segmentation points from DNSC08MSS model.Differences of the measured and modeled deflections of the vertical are calculated at four points on both sides and linearly change along the route.So the deflections of the vertical along the route over the sea can be improved by the linear interpolation model.The results are also in accord with those of trigonometirc levelings.The practical case shows that we can precisely connect the orthometric height across the Qiongzhou Strait to satisfy the requirement of order 3 leveling network of China.The method is very efficient to precisely connect the height datum across the sea along the route up to 80 km.

  1. What is the Planetary Boundary Layer Height in a Global Perspective?

    Science.gov (United States)

    Xie, F.; Syndergaard, S.; von Engeln, A.

    2014-12-01

    The planetary boundary layer (PBL) height is a fundamental parameter characterizing the vertical extent of atmospheric mixing near the surface. It is critical for understanding the PBL process and low cloud evolution and its feedback on the climate system, which remains a key uncertainty in climate modeling. The PBL height is generally defined as the altitude of a transition layer where air temperature or humidity gradient are significant within the lowest 1-5 kilometers above the surface. Numerous thermodynamic parameters, including temperature, humidity (specific/relative humidity) and their derivatives (e.g., potential/virtual potential temperature etc.) have been widely used to define the PBL height. Advances in satellite remote sensing technique allow novel ways to detect the PBL heights from space. Many new parameters are proposed for PBL height detection including GPS radio occultation (RO) measurements (e.g., refractivity, bending angle and dry-temperature) and CALIPSO lidar backscattering measurements (e.g., cloud-top-height). Large discrepancy among various PBL height definitions was revealed from radiosonde analyses, which however are restricted over lands and represent limited horizontal scales of atmospheric conditions. In this talk, we investigate the definition difference in a global perspective by using multi-year high-resolution ERA-interim (1 degree grid with 60 vertical layers) global analysis. Automatic algorithms are applied to compute the PBL heights with various physical parameters (both conventional and GPS RO) at each model grid. The global PBL height seasonal climatology and the difference among the climatologies are derived. Large discrepancy between the thermal-based and humidity-based PBL height definitions is most prominent over tropical and polar regions. Humidity-based PBL heights become problematic over dry regions, especially over high-latitude in winter season. The cloud-top height from CALIPSO is consistent with most physical

  2. Growth in Total Height and Its Components and Cardiometabolic Health in Childhood

    DEFF Research Database (Denmark)

    Haugaard, Line Klingen; Baker, Jennifer Lyn; Perng, Wei;

    2016-01-01

    was a cardiometabolic risk score based on sex-specific internal z-scores for systolic blood pressure, waist circumference, homeostatic model assessment of insulin resistance, triglycerides and high-density lipoprotein-cholesterol. RESULTS: Mean (SD) total height was 97.9 (4.5) cm in boys and 97.1 (4.7) cm in girls...

  3. Optimization of thermal fly-height control slider geometry for Tbit/in^2 recording

    NARCIS (Netherlands)

    Vakis, Antonis I.; Polycarpou, Andreas A.

    2010-01-01

    Magnetic storage advances including thermal fly-height control (TFC) technology were able to reduce the clearance between the read/write elements of the slider and the disk surface to increase the recording density of hard disk drives without compromising the stability of the head–disk interface (HD

  4. Prediction of Canopy Heights over a Large Region Using Heterogeneous Lidar Datasets: Efficacy and Challenges

    Directory of Open Access Journals (Sweden)

    Ranjith Gopalakrishnan

    2015-08-01

    Full Text Available Generating accurate and unbiased wall-to-wall canopy height maps from airborne lidar data for large regions is useful to forest scientists and natural resource managers. However, mapping large areas often involves using lidar data from different projects, with varying acquisition parameters. In this work, we address the important question of whether one can accurately model canopy heights over large areas of the Southeastern US using a very heterogeneous dataset of small-footprint, discrete-return airborne lidar data (with 76 separate lidar projects. A unique aspect of this effort is the use of nationally uniform and extensive field data (~1800 forested plots from the Forest Inventory and Analysis (FIA program of the US Forest Service. Preliminary results are quite promising: Over all lidar projects, we observe a good correlation between the 85th percentile of lidar heights and field-measured height (r = 0.85. We construct a linear regression model to predict subplot-level dominant tree heights from distributional lidar metrics (R2 = 0.74, RMSE = 3.0 m, n = 1755. We also identify and quantify the importance of several factors (like heterogeneity of vegetation, point density, the predominance of hardwoods or softwoods, the average height of the forest stand, slope of the plot, and average scan angle of lidar acquisition that influence the efficacy of predicting canopy heights from lidar data. For example, a subset of plots (coefficient of variation of vegetation heights <0.2 significantly reduces the RMSE of our model from 3.0–2.4 m (~20% reduction. We conclude that when all these elements are factored into consideration, combining data from disparate lidar projects does not preclude robust estimation of canopy heights.

  5. Auto-correlation analysis of wave heights in the Bay of Bengal

    Indian Academy of Sciences (India)

    Abhijit Sarkar; Jignesh Kshatriya; K Satheesan

    2006-04-01

    Time series observations of significant wave heights in the Bay of Bengal were subjected to auto-correlation analysis to determine temporal variability scale.The analysis indicates an exponential fall of auto-correlation in the first few hours with a decorrelation time scale of about six hours.A similar figure was found earlier for ocean surface winds.The nature of variation of auto-correlation with time lags was also found to be similar for winds and wave heights.

  6. Helicity at Photospheric and Chromospheric Heights

    CERN Document Server

    Tiwari, S K; Sankarasubramanian, K

    2009-01-01

    In the solar atmosphere the twist parameter $\\alpha$ has the same sign as magnetic helicity. It has been observed using photospheric vector magnetograms that negative/positive helicity is dominant in the northern/southern hemisphere of the Sun. Chromospheric features show dextral/sinistral dominance in the northern/southern hemisphere and sigmoids observed in X-rays also have a dominant sense of reverse-S/forward-S in the northern/southern hemisphere. It is of interest whether individual features have one-to-one correspondence in terms of helicity at different atmospheric heights. We use UBF \\Halpha images from the Dunn Solar Telescope (DST) and other \\Halpha data from Udaipur Solar Observatory and Big Bear Solar Observatory. Near-simultaneous vector magnetograms from the DST are used to establish one-to-one correspondence of helicity at photospheric and chromospheric heights. We plan to extend this investigation with more data including coronal intensities.

  7. BOREAS AFM-6 Boundary Layer Height Data

    Science.gov (United States)

    Wilczak, James; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-6 team from National Oceanic and Atmospheric Adminsitration/Environment Technology Laboratory (NOAA/ETL) operated a 915-MHz wind/Radio Acoustic Sounding System (RASS) profiler system in the Southern Study Area (SSA) near the Old Jack Pine (OJP) site. This data set provides boundary layer height information over the site. The data were collected from 21 May 1994 to 20 Sep 1994 and are stored in tabular ASCII files. The boundary layer height data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  8. Adaptive Layer Height During DLP Materials Processing

    DEFF Research Database (Denmark)

    Pedersen, David Bue; Zhang, Yang; Nielsen, Jakob Skov

    2016-01-01

    for considerable process speedup during the Additive Manufacture of components that contain areas of low cross-section variability, at no loss of surface quality. The adaptive slicing strategy was tested with a purpose built vat polymerisation system and numerical engine designed and constructed to serve as a Next......This research aim to show how manufacturing speeds during vat polymerisation can be vastly increased through an adaptive layer height strategy that takes the geometry into account through analysis of the relationship between layer height, cross-section variability and surface structure. This allows......-Gen technology platform. By means of assessing hemispherical manufactured test specimen and through 3D surface mapping with variable-focus microscopy and confocal microscopy, a balance between minimal loss of surface quality with a maximal increase of manufacturing rate has been identified as a simple angle...

  9. Height predicts jealousy differently for men and women

    NARCIS (Netherlands)

    Buunk, Abraham P.; Park, Justin H.; Zurriaga, Rosario; Klavina, Liga; Massar, Karlijn

    Because male height is associated with attractiveness, dominance, and reproductive success, taller men may be less jealous. And because female height has a curvilinear relationship with health and reproductive success (with average-height females having the advantages), female height may have a

  10. Leg length, sitting height and postmenopausal breast cancer risk

    DEFF Research Database (Denmark)

    Mellemkjær, L; Christensen, J; Frederiksen, K

    2012-01-01

    Tallness has consistently been associated with an increased risk of breast cancer. We investigated the association further by decomposing height into leg length and sitting height.......Tallness has consistently been associated with an increased risk of breast cancer. We investigated the association further by decomposing height into leg length and sitting height....

  11. Height predicts jealousy differently for men and women

    NARCIS (Netherlands)

    Buunk, Abraham P.; Park, Justin H.; Zurriaga, Rosario; Klavina, Liga; Massar, Karlijn

    2008-01-01

    Because male height is associated with attractiveness, dominance, and reproductive success, taller men may be less jealous. And because female height has a curvilinear relationship with health and reproductive success (with average-height females having the advantages), female height may have a curv

  12. EMPLOYING TOPOGRAPHICAL HEIGHT MAP IN COLONIC POLYP MEASUREMENT AND FALSE POSITIVE REDUCTION.

    Science.gov (United States)

    Yao, Jianhua; Li, Jiang; Summers, Ronald M

    2009-01-01

    CT Colonography (CTC) is an emerging minimally invasive technique for screening and diagnosing colon cancers. Computer Aided Detection (CAD) techniques can increase sensitivity and reduce false positives. Inspired by the way radiologists detect polyps via 3D virtual fly-through in CTC, we borrowed the idea from geographic information systems to employ topographical height map in colonic polyp measurement and false positive reduction. After a curvature based filtering and a 3D CT feature classifier, a height map is computed for each detection using a ray-casting algorithm. We design a concentric index to characterize the concentric pattern in polyp height map based on the fact that polyps are protrusions from the colon wall and round in shape. The height map is optimized through a multi-scale spiral spherical search to maximize the concentric index. We derive several topographic features from the map and compute texture features based on wavelet decomposition. We then send the features to a committee of support vector machines for classification. We have trained our method on 394 patients (71 polyps) and tested it on 792 patients (226 polyps). Results showed that we can achieve 95% sensitivity at 2.4 false positives per patient and the height map features can reduce false positives by more than 50%. We compute the polyp height and width measurements and correlate them with manual measurements. The Pearson correlations are 0.74 (p=0.11) and 0.75 (p=0.17) for height and width, respectively.

  13. Feynman amplitudes and limits of heights

    Science.gov (United States)

    Amini, O.; Bloch, S. J.; Burgos Gil, J. I.; Fresán, J.

    2016-10-01

    We investigate from a mathematical perspective how Feynman amplitudes appear in the low-energy limit of string amplitudes. In this paper, we prove the convergence of the integrands. We derive this from results describing the asymptotic behaviour of the height pairing between degree-zero divisors, as a family of curves degenerates. These are obtained by means of the nilpotent orbit theorem in Hodge theory.

  14. Algorithmic height compression of unordered trees.

    Science.gov (United States)

    Ben-Naoum, Farah; Godin, Christophe

    2016-01-21

    By nature, tree structures frequently present similarities between their sub-parts. Making use of this redundancy, different types of tree compression techniques have been designed in the literature to reduce the complexity of tree structures. A popular and efficient way to compress a tree consists of merging its isomorphic subtrees, which produces a directed acyclic graph (DAG) equivalent to the original tree. An important property of this method is that the compressed structure (i.e. the DAG) has the same height as the original tree, thus limiting partially the possibility of compression. In this paper we address the problem of further compressing this DAG in height. The difficulty is that compression must be carried out on substructures that are not exactly isomorphic as they are strictly nested within each-other. We thus introduced a notion of quasi-isomorphism between subtrees that makes it possible to define similar patterns along any given path in a tree. We then proposed an algorithm to detect these patterns and to merge them, thus leading to compressed structures corresponding to DAGs augmented with return edges. In this way, redundant information is removed from the original tree in both width and height, thus achieving minimal structural compression. The complete compression algorithm is then illustrated on the compression of various plant-like structures.

  15. A global boundary-layer height climatology

    Energy Technology Data Exchange (ETDEWEB)

    Dop, H. van; Krol, M.; Holtslag, B. [Inst. for Marine and Atmospheric Research Utrecht, IMAU, Utrecht (Netherlands)

    1997-10-01

    In principle the ABL (atmospheric boundary layer) height can be retrieved from atmospheric global circulation models since they contain algorithms which determine the intensity of the turbulence as a function of height. However, these data are not routinely available, or on a (vertical) resolution which is too crude in view of the application. This justifies the development of a separate algorithm in order to define the ABL. The algorithm should include the generation of turbulence by both shear and buoyancy and should be based on readily available atmospheric parameters. There is obviously a wide application for boundary heights in off-line global and regional chemistry and transport modelling. It is also a much used parameter in air pollution meteorology. In this article we shall present a theory which is based on current insights in ABL dynamics. The theory is applicable over land and sea surfaces in all seasons. The theory is (for various reasons) not valid in mountainous areas. In areas where boundary-layer clouds or deep cumulus convection are present the theory does not apply. However, the same global atmospheric circulation models contain parameterizations for shallow and deep convection from which separate estimates can be obtained for the extent of vertical mixing. (au)

  16. A brief treatment for fear of heights.

    Science.gov (United States)

    Arroll, Bruce; Henwood, Suzanne M; Sundram, Fred I; Kingsford, Douglas W; Mount, Vicki; Humm, Steve P; Wallace, Henry B; Pillai, Avinesh

    2017-01-01

    Objective To assess the effectiveness of a novel imaginal intervention for people with acrophobia. Methods The design was a randomized controlled trial with concealed randomization and blinded to other participants' intervention. The intervention was a single novel imaginal intervention session or a 15-min meditation. The setting was in Auckland, New Zealand. The participants were a convenience sample of the public with a score >29 on the Heights Interpretation Questionnaire (HIQ), a questionnaire validated against actual height exposure. The primary outcomes were the proportion of participants with a score fear of heights is very much improved. There was a 4.5-point difference in the HIQ score at eight weeks (p = 0.055) on the multiple regression analysis. Conclusions This is the first randomized trial of this novel imaginal intervention which is probably effective, brief, easily learnt, and safe. It may be worth considering doing this prior to some of the longer or more expensive exposure therapies. This study will be of interest to family doctors, psychiatrists, and psychologists.

  17. Frequency and zero-point vibrational energy scale factors for double-hybrid density functionals (and other selected methods): can anharmonic force fields be avoided?

    Science.gov (United States)

    Kesharwani, Manoj K; Brauer, Brina; Martin, Jan M L

    2015-03-05

    We have obtained uniform frequency scaling factors λ(harm) (for harmonic frequencies), λ(fund) (for fundamentals), and λ(ZPVE) (for zero-point vibrational energies (ZPVEs)) for the Weigend-Ahlrichs and other selected basis sets for MP2, SCS-MP2, and a variety of DFT functionals including double hybrids. For selected levels of theory, we have also obtained scaling factors for true anharmonic fundamentals and ZPVEs obtained from quartic force fields. For harmonic frequencies, the double hybrids B2PLYP, B2GP-PLYP, and DSD-PBEP86 clearly yield the best performance at RMSD = 10-12 cm(-1) for def2-TZVP and larger basis sets, compared to 5 cm(-1) at the CCSD(T) basis set limit. For ZPVEs, again, the double hybrids are the best performers, reaching root-mean-square deviations (RMSDs) as low as 0.05 kcal/mol, but even mainstream functionals like B3LYP can get down to 0.10 kcal/mol. Explicitly anharmonic ZPVEs only are marginally more accurate. For fundamentals, however, simple uniform scaling is clearly inadequate.

  18. A constant limiting mass scale for flat early-type galaxies from z=1 to z=0: density evolves but shapes do not

    CERN Document Server

    Holden, Bradford; Rix, Hans-Walter; Franx, Marijn

    2011-01-01

    We measure the evolution in the intrinsic shape distribution of early-type galaxies from z~1 to z~0 by analyzing their projected axis-ratio distributions. We extract a low-redshift sample (0.04 1e11 M_sun) is 2:3, where as at masses below 1e11 M_sun this ratio narrows to 1:3, or more flattened galaxies. In an entirely analogous manner we select a high-redshift sample (0.6 3e10 M_sun with redshift. At the same time, our samples imply an increase of 2-3x in co-moving number density for early-type galaxies at masses >3e10 M_sun, in agreement with previous studies. Given the direct connection between the axis-ratio distribution and the underlying bulge-to-disk ratio distribution, our findings imply that the number density evolution of early-type galaxies is not exclusively driven by the emergence of either bulge- or disk-dominated galaxies, but rather by a balanced mix that depends only on the stellar mass of the galaxy. The challenge for galaxy formation models is to reproduce this overall non-evolving ratio of ...

  19. Tree diversity, tree height and environmental harshness in eastern and western North America.

    Science.gov (United States)

    Marks, Christian O; Muller-Landau, Helene C; Tilman, David

    2016-07-01

    Does variation in environmental harshness explain local and regional species diversity gradients? We hypothesise that for a given life form like trees, greater harshness leads to a smaller range of traits that are viable and thereby also to lower species diversity. On the basis of a strong dependence of maximum tree height on site productivity and other measures of site quality, we propose maximum tree height as an inverse measure of environmental harshness for trees. Our results show that tree species richness is strongly positively correlated with maximum tree height across multiple spatial scales in forests of both eastern and western North America. Maximum tree height co-varied with species richness along gradients from benign to harsh environmental conditions, which supports the hypothesis that harshness may be a general mechanism limiting local diversity and explaining diversity gradients within a biogeographic region.

  20. Assessing a Template Matching Approach for Tree Height and Position Extraction from Lidar-Derived Canopy Height Models of Pinus Pinaster Stands

    Directory of Open Access Journals (Sweden)

    Francesco Pirotti

    2010-10-01

    Full Text Available In this paper, an assessment of a method using a correlation filter over a lidar-derived digital canopy height model (CHM is presented. The objective of the procedure is to obtain stem density, position, and height values, on a stand with the following characteristics: ellipsoidal canopy shape (Pinus pinaster, even-aged and single-layer structure. The process consists of three steps: extracting a correlation map from CHM by applying a template whose size and shape resembles the canopy to be detected, applying a threshold mask to the correlation map to keep a subset of candidate-pixels, and then applying a local maximum filter to the remaining pixel groups. The method performs satisfactorily considering the experimental conditions. The mean tree extraction percentage is 65% with a coefficient of agreement of 0.4. The mean absolute error of height is ~0.5 m for all plots except one. It can be considered a valid approach for extracting tree density and height in regularly spaced stands (i.e., poplar plantations which are fundamental for extracting related forest parameters such as volume and biomass.