544 research outputs found

    Aggregating available soil water holding capacity data for crop yield models

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    The total amount of water available to plants that is held against gravity in a soil is usually estimated as the amount present at -0.03 MPa average water potential minus the amount present at -1.5 MPa water potential. This value, designated available water-holding capacity (AWHC), is a very important soil characteristic that is strongly and positively correlated to the inherent productivity of soils. In various applications, including assessing soil moisture status over large areas, it is necessary to group soil types or series as to their productivity. Current methods to classify AWHC of soils consider only total capacity of soil profiles and thus may group together soils which differ greatly in AWHC as a function of depth in the profile. A general approach for evaluating quantitatively the multidimensional nature of AWHC in soils is described. Data for 902 soil profiles, representing 184 soil series, in Indiana were obtained from the Soil Characterization Laboratory at Purdue University. The AWHC for each of ten 150-mm layers in each soil was established, based on soil texture and parent material. A multivariate clustering procedure was used to classify each soil profile into one of 4, 8, or 12 classes based upon ten-dimensional AWHC values. The optimum number of classes depends on the range of AWHC in the population of oil profiles analyzed and on the sensitivity of a crop to differences in distribution of water within the soil profile

    Aerosol particles in the mexican east pacific part I: processing and vertical redistribution by clouds

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    International audienceAirborne measurements of aerosol particle size distributions were made in the Mexican Intertropical Convergence Zone. The shape of the spectra at cloud base was compared with those at higher altitudes and near cloud boundaries to identify signatures of cloud processed particles. Of 78 cases analyzed, 71% showed enhancement in volume of super-micron particles, 49% had enhanced volume of sub-micron particles, 28% were homogeneous mixtures with boundary layer air, and 24% had super-micron particles removed by precipitation. Almost 100% of the cases with enhanced volume in sub-micron particles also occurred with enhanced super-micron volume. The enhanced volume in super-micron particles is approximately 10 times larger than the sub-micron enhancement. Cloud processed particles in marine air masses had twice as much enhancement of super-micron mass than found in particles processed by clouds formed from continental sources, likely a result of a more efficient coalescence process in clean, maritime clouds. These results are in qualitative agreement with previous observational and theoretical studies that relate enhancements in particle mass to the uptake by cloud droplets of SO2 and subsequent growth by coalescence

    Use of high-dimensional spectral data to evaluate organic matter, reflectance relationships in soils

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    Recent breakthroughs in remote sensing technology have led to the development of a spaceborne high spectral resolution imaging sensor, HIRIS, to be launched in the mid-1990s for observation of earth surface features. The effects of organic carbon content on soil reflectance over the spectral range of HIRIS, and to examine the contributions of humic and fulvic acid fractions to soil reflectance was evaluated. Organic matter from four Indiana agricultural soils was extracted, fractionated, and purified, and six individual components of each soil were isolated and prepared for spectral analysis. The four soils, ranging in organic carbon content from 0.99 percent, represented various combinations of genetic parameters such as parent material, age, drainage, and native vegetation. An experimental procedure was developed to measure reflectance of very small soil and organic component samples in the laboratory, simulating the spectral coverage and resolution of the HIRIS sensor. Reflectance in 210 narrow (10 nm) bands was measured using the CARY 17D spectrophotometer over the 400 to 2500 nm wavelength range. Reflectance data were analyzed statistically to determine the regions of the reflective spectrum which provided useful information about soil organic matter content and composition. Wavebands providing significant information about soil organic carbon content were located in all three major regions of the reflective spectrum: visible, near infrared, and middle infrared. The purified humic acid fractions of the four soils were separable in six bands in the 1600 to 2400 nm range, suggesting that longwave middle infrared reflectance may be useful as a non-destructive laboratory technique for humic acid characterization

    Aerosol particles in the Mexican East Pacific <BR> Part I: processing and vertical redistribution by clouds

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    International audienceAirborne measurements of aerosol particle size distributions were made in the Mexican Intertropical Convergence Zone. The volume concentrations of submicron and super micron particles at cloud base were compared with those in near-cloud regions over a range of altitudes. Of 78 near-cloud regions analyzed, 68% and 45% had enhanced volumes of submicron particles and supermicron particles, respectively. In addition, 35% of these regions had supermicron particles removed, presumably by precipitation. In 61% of the cases the enhancement in volume occurred over the size range from 0.1 to 50 ?m whereas only submicron volumes were enhanced in 35% of the cases. In regions near clouds that were formed in air of maritime origin the frequency of volume enhancement decreased with increasing altitude and was twice as frequent on the dissipating side of clouds compared to the growing side. No such differences were found in the regions near clouds formed in air originating from the land. The frequency and average magnitude of volume enhancement are in qualitative and quantitative agreement with previous observational and theoretical studies that relate enhancements in particle mass to the uptake by cloud droplets of SO2 accompanied by additional growth by droplet coalescence

    Stable Mode Sorting by Two-Dimensional Parity of Photonic Transverse Spatial States

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    We describe a mode sorter for two-dimensional parity of transverse spatial states of light based on an out-of-plane Sagnac interferometer. Both Hermite-Gauss (HG) and Laguerre-Gauss (LG) modes can be guided into one of two output ports according to the two-dimensional parity of the mode in question. Our interferometer sorts HG_nm input modes depending upon whether they have even or odd order n+m; it equivalently sorts LG modes depending upon whether they have an even or odd value of their orbital angular momentum. It functions efficiently at the single-photon level, and therefore can be used to sort single-photon states. Due to the inherent phase stability of this type of interferometer as compared to those of the Mach-Zehnder type, it provides a promising tool for the manipulation and filtering of higher order transverse spatial modes for the purposes of quantum information processing. For example, several similar Sagnacs cascaded together may allow, for the first time, a stable measurement of the orbital angular momentum of a true single-photon state. Furthermore, as an alternative to well-known holographic techniques, one can use the Sagnac in conjunction with a multi-mode fiber as a spatial mode filter, which can be used to produce spatial-mode entangled Bell states and heralded single photons in arbitrary first-order (n+m=1) spatial states, covering the entire Poincare sphere of first-order transverse modes.Comment: 11 pages, 12 figures, 2 appendice

    Adam and Eve, Designed Diversity, and Allele Frequencies

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    Theistic evolutionists present multiple genetic arguments against a literal Adam and Eve. One key argument asserts it would be impossible for a single human couple to give rise to the genetic diversity seen in the modern human population. This implicitly assumes Adam and Eve would have been created without internal genetic diversity. If this were true, all observed variations would have to arise recently via random mutations. This would require incredibly high mutation rates, logically leading to rapid extinction. Yet, Adam and Eve could have been created massively heterozygous. We have argued for over a decade that they could have been created with “designed diversity”. We have previously shown that a vast amount of genetic variation could have been pre-programmed into their genomes. This could logically provide the genetic basis for: 1) our human gifts and talents; 2) the many forms of human beauty; and 3) the various ways people have rapidly adapted to new habitats. It is also claimed that the currently observed human allele frequency patterns could not arise from a single couple. The logic here is that, since there were only four sets of chromosomes in Eden, all variants would have had an initial frequency of either 25%, 50%, or 75%. Today, most allelic variants have frequencies in the range of 0–10%. Therefore, it is claimed that observed human diversity disproves a literal Adam and Eve. In this paper we have critically examined these arguments. Our analyses highlight several genetic mechanisms that can help reconcile a literal Adam and Eve with the human allele frequency distributions seen today. We use numerical simulation to show that two people, if they contain designed alleles, can in fact give rise to allele frequency distributions of the very same type as are now seen in modern man. We cannot know how God created Adam and Eve, nor exactly how Adam and Eve gave rise to the current human population. However, the genetic argument that there is no way that a literal Adam and Eve could have given rise to the observed human allele frequencies is clearly over-reaching and appears to be theologically reckless. There is no compelling reason to reject Adam and Eve based on modern allele frequencies

    Physical and chemical properties of non-exhaust particles generated from wear between pavements and tyres

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    A road simulator was used to generate wear particles from the interaction between two tyre brands and a composite pavement. Particle size distributions were monitored using a scanning mobility particle sizer and an aerosol particle sizer. Continuous measurements of particle mass concentrations were also made. Collection of inhalable particles (PM10) was conducted using a high-volume sampler equipped with quartz filters, which were then analysed for organic and elemental carbon, organic constituents and elemental composition. Tyre fragments chopped into tiny chips were also subjected to detailed organic and elemental speciation. The number concentration was dominated by particles 0.5 μm. The emission factor from wear between pavements and tyres was of the order of 2 mg km−1 veh−1. Organic carbon represented about 10% of the PM10 mass, encompassing multiple aliphatic compounds (n-alkanes, alkenes, hopanes, and steranes), PAHs, thiazols, n-alkanols, polyols, some fragrant compounds, sugars, triterpenoids, sterols, phenolic constituents, phthalate plasticisers and several types of acids, among others. The relationship between airborne particulate organic constituents and organic matter in tyre debris is discussed. The detection of compounds that have been extensively used as biomass burning tracers (e.g. retene, dehydroabietic acid and levoglucosan) in both the shredded tiny tyre chips and the wear particles from the interaction between tyres and pavement puts into question their uniqueness as markers of wood combustion. Trace and major elements accounted for about 5% of the mass of the tyre fragments but represented 15–18% of the PM10 from wear, denoting the contribution of mineral elements from the pavement. Sulphur and zinc were abundant constituents in all samples.publishe

    Cloud Ice Properties: In Situ Measurement Challenges

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    Baumgardner D., S.J. Abel, D. Axisa, R. Cotton, J. Crosier, P. Field, C. Gurganus, A. Heymsfield, A. Korolev, M. Krämer, P. Lawson, G. McFarquhar, Z. Ulanowski, and J. Um, 'Cloud ice properties: in situ measurement challenges', Meteorological Monographs, Vol. 58, pp. 9.1–9.23, April 2017. The version of record is available online at doi: 10.1175/AMSMONOGRAPHS-D-16-0011.1.1 © 2017 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).Understanding the formation and evolution of ice in clouds requires detailed information on the size, shape, mass and optical properties of individual cloud hydrometeors and their bulk properties over a broad range of atmospheric conditions. Since the 1960s, instrumentation and research aircraft have evolved providing increasingly more accurate and larger quantities of data about cloud particle properties. In this chapter we review the current status of electrical powered, in situ measurement systems with respect to their strengths and weaknesses and document their limitations and uncertainties. There remain many outstanding challenges. These are summarized and accompanied by recommendations for moving forward. through new developments that fill the remaining information gaps. Closing these gaps will remove the obstacles that continue to hinder our understanding of cloud processes in general and the evolution of ice in particular.Peer reviewe

    A new method to estimate cloud cover fraction over El Leoncito Observatory from an all-sky imager designed for upper atmosphere studies

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    A method for determining cloud cover fraction over El Leoncito Observatory (31.8°S, 69.3°W) is presented. Data from an all-sky imaging system, designed to measure nightglow originating from the mesosphere and thermosphere, is used to determine the fraction of the sky covered by clouds. More than 9,000 hr of observations from May 2006 to December 2010 are used to show that El Leoncito is clear approximately 75-80% of the time. No significant seasonal variations are observed. The optical ground-based data are compared with data from the Moderate Resolution Imaging Spectro-radiometer (MODIS) instrument on board the TERRA and AQUA satellites.Fil: Martinis, C.. University Of Boston; Estados Unidos de América;Fil: Wilson, J.. University of New Hampshire; Estados UnidosFil: Zablowski, P.. University Of Boston; Estados Unidos de América;Fil: Baumgardner, J.. University Of Boston; Estados Unidos de América;Fil: Aballay, Jose Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Complejo Astronómico "El Leoncito". Universidad Nacional de Córdoba. Complejo Astronómico "El Leoncito". Universidad Nacional de la Plata. Complejo Astronómico "El Leoncito". Universidad Nacional de San Juan. Complejo Astronómico "El Leoncito"; ArgentinaFil: Garcia, Beatriz Elena. Universidad Tecnologica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Pque. Centenario. Instituto de Tecnología En Detección y Astropartículas. Itedam - Subsede del Instituto de Tec. En Detección y Astropartículas Mendoza | Comisión Nacional de Energía Atómica. Instituto de Tecnología En Detección y Astropartículas. Itedam - Subsede del Instituto de Tec. En Detección y Astropartículas Mendoza | Universidad Nacional de San Martin. Instituto de Tecnología En Detección y Astropartículas. Itedam - Subsede del Instituto de Tec. En Detección y Astropartículas Mendoza. ; Argentina; ArgentinaFil: Ristori, Pablo Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; ArgentinaFil: Otero, Lidia Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo Estratégico para la Defensa. Ministerio de Defensa. Unidad de Investigación y Desarrollo Estratégico para la Defensa; Argentin
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