342 research outputs found

    Relationship Between Soil Moisture and Soil Surface Temperature

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    Thermal-infrared imagery (thermography) obtained from satellite altitudes has been shown to be a promising new tool for resource management and development. Satellite-borne thermal-infrared sensors allow the collection of time-sequential thermal-infrared radiation (thermal emittance) data over large land surface areas of the earth at relatively low cost. Thus, any resource which can be related to thermal emittance can be readily monitored. Thermal emittance from a surface is proportional to the fourth power of the surface temperature. Thus any factor which affects the surface temperature greatly affects the surface thermal emittance. · Moisture is such a factor when the land surface is considered. Near surface soil moisture changes the heat capacity and thermal conductivity of the soil and thus greatly alters the temperature of the land surface. Thermography is very sensitive to such changes in surface temperature making it a potentially useful tool for monitoring near surface soil moisture. Factors other than soil moisture also affect soil surface temperature and thus thermal emittance. These factors such as near surface ground water, wind velocity, topography of the land, plant canopy, soil type, and other variables serve to complicate the method. Thus, the isolation of one factor such as soil moisture and its effect on thermal emittance is difficult. Therefore, the interrelationship between these factors must be understood before a model that describes variations in thermal emittance can be constructed. The resource scientist may then be able either to compensate for the effect of these factors during data analysis or collect data when these factors have a minimal effect on the thermal emittance of the land-surface. The specific objectives of this research concerning the .testing and modification of the model for monitoring soil moisture were: 1. To investigate the relationship between soil surface temperature differences and soil moisture differences as predicted by the existing heat flow model. 2. To investigate the relationship between surface soil heat flux and calculated surface temperature differences predicted by the same existing theoretical model. 3. To modify the existing heat flow model to accept plant parameters as inputs. 4. To test the modified theoretical model by comparing predicted surface temperature differences with apparent temperature difference acquired experimentally over two plots with an oats crop canopy

    Bridging the Gap: International Organizations as Organizations

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    http://deepblue.lib.umich.edu/bitstream/2027.42/51108/1/340.pd

    Guest Editorial: Nonlinear Optimization of Communication Systems

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    Linear programming and other classical optimization techniques have found important applications in communication systems for many decades. Recently, there has been a surge in research activities that utilize the latest developments in nonlinear optimization to tackle a much wider scope of work in the analysis and design of communication systems. These activities involve every “layer” of the protocol stack and the principles of layered network architecture itself, and have made intellectual and practical impacts significantly beyond the established frameworks of optimization of communication systems in the early 1990s. These recent results are driven by new demands in the areas of communications and networking, as well as new tools emerging from optimization theory. Such tools include the powerful theories and highly efficient computational algorithms for nonlinear convex optimization, together with global solution methods and relaxation techniques for nonconvex optimization

    Performative, Informative and Emotive Systems The First Piece of the PIE

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    This paper distinguishes computer and communications systems that\u27perform\u27 fr om those that\u27inform\u27 and those that deal with emotive aspects of problems. It indicates some of the ways that peformative systems seem to differ from the other kinds, why this distinction is important to both users and designers, and suggests research-some of it currently underway-to investigate this area. Results from this research will allow us to improve existing performative systems and to expand the domain of their application

    Sonophenology: A Tangible Interface for Sonification of Geo-Spatial Phenological Data at Multiple Time-scales

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    Presented at the 16th International Conference on Auditory Display (ICAD2010) on June 9-15, 2010 in Washington, DC.Phenology is the study of periodic biological processes, such as when plants flower and birds arrive in the spring. In this paper we sonify phenology data and control the sonification process through a tangible interface consisting of a physical paper map and tracking of fiducial markers. The designed interface enables one or more users to concurrently specify point and range queries in both time and space and receive immediate sonic feedback. This system can be used to study and explore the effects of climate change, both as tool to be used by scientists, and as a way to educate members of the general public

    Current-Voltage Curves for Molecular Junctions Computed Using All-Electron Basis Sets

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    We present current-voltage (I-V) curves computed using all-electron basis sets on the conducting molecule. The all-electron results are very similar to previous results obtained using effective core potentials (ECP). A hybrid integration scheme is used that keeps the all-electron calculations cost competitive with respect to the ECP calculations. By neglecting the coupling of states to the contacts below a fixed energy cutoff, the density matrix for the core electrons can be evaluated analytically. The full density matrix is formed by adding this core contribution to the valence part that is evaluated numerically. Expanding the definition of the core in the all-electron calculations significantly reduces the computational effort and, up to biases of about 2 V, the results are very similar to those obtained using more rigorous approaches. The convergence of the I-V curves and transmission coefficients with respect to basis set is discussed. The addition of diffuse functions is critical in approaching basis set completeness

    Pervasive Phylogenomic Incongruence Underlies Evolutionary Relationships in Eyebrights (Euphrasia, Orobanchaceae)

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    Disentangling the phylogenetic relationships of taxonomically complex plant groups is often mired by challenges associated with recent speciation, hybridization, complex mating systems, and polyploidy. Here, we perform a phylogenomic analysis of eyebrights (Euphrasia), a group renowned for taxonomic complexity, with the aim of documenting the extent of phylogenetic discordance at both deep and at shallow phylogenetic scales. We generate whole-genome sequencing data and integrate this with prior genomic data to perform a comprehensive analysis of nuclear genomic, nuclear ribosomal (nrDNA), and complete plastid genomes from 57 individuals representing 36 Euphrasia species. The species tree analysis of 3,454 conserved nuclear scaffolds (46 Mb) reveals that at shallow phylogenetic scales postglacial colonization of North Western Europe occurred in multiple waves from discrete source populations, with most species not being monophyletic, and instead combining genomic variants from across clades. At a deeper phylogenetic scale, the Euphrasia phylogeny is structured by geography and ploidy, and partially by taxonomy. Comparative analyses show Southern Hemisphere tetraploids include a distinct subgenome indicative of independent polyploidy events from Northern Hemisphere taxa. In contrast to the nuclear genome analyses, the plastid genome phylogeny reveals limited geographic structure, while the nrDNA phylogeny is informative of some geographic and taxonomic affinities but more thorough phylogenetic inference is impeded by the retention of ancestral polymorphisms in the polyploids. Overall our results reveal extensive phylogenetic discordance at both deeper and shallower nodes, with broad-scale geographic structure of genomic variation but a lack of definitive taxonomic signal. This suggests that Euphrasia species either have polytopic origins or are maintained by narrow genomic regions in the face of extensive homogenizing gene flow. Moreover, these results suggest genome skimming will not be an effective extended barcode to identify species in groups such as Euphrasia, or many other postglacial species groups

    Pan-chromatic observations of the remarkable nova LMC 2012

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    We present the results of an intensive multiwavelength campaign on nova LMC 2012. This nova evolved very rapidly in all observed wavelengths. The time to fall two magnitudes in the V band was only 2 days. In X-rays the super soft phase began 13±\pm5 days after discovery and ended around day 50 after discovery. During the super soft phase, the \Swift/XRT and \Chandra\ spectra were consistent with the underlying white dwarf being very hot, \sim 1 MK, and luminous, \sim 1038^{38} erg s1^{-1}. The UV, optical, and near-IR photometry showed a periodic variation after the initial and rapid fading had ended. Timing analysis revealed a consistent 19.24±\pm0.03 hr period in all UV, optical, and near-IR bands with amplitudes of \sim 0.3 magnitudes which we associate with the orbital period of the central binary. No periods were detected in the corresponding X-ray data sets. A moderately high inclination system, ii = 60±\pm10^{\arcdeg}, was inferred from the early optical emission lines. The {\it HST}/STIS UV spectra were highly unusual with only the \ion{N}{5} (1240\AA) line present and superposed on a blue continuum. The lack of emission lines and the observed UV and optical continua from four epochs can be fit with a low mass ejection event, \sim 106^{-6} M_{\odot}, from a hot and massive white dwarf near the Chandrasekhar limit. The white dwarf, in turn, significantly illuminated its subgiant companion which provided the bulk of the observed UV/optical continuum emission at the later dates. The inferred extreme white dwarf characteristics and low mass ejection event favor nova LMC 2012 being a recurrent nova of the U Sco subclass.Comment: 18 figures, 6 tables (one online only containing all the photometry

    Objectively measured physical activity and fat mass in a large cohort of children

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    Background Previous studies have been unable to characterise the association between physical activity and obesity, possibly because most relied on inaccurate measures of physical activity and obesity. Methods and Findings We carried out a cross sectional analysis on 5,500 12-year-old children enrolled in the Avon Longitudinal Study of Parents and Children. Total physical activity and minutes of moderate and vigorous physical activity (MVPA) were measured using the Actigraph accelerometer. Fat mass and obesity (defined as the top decile of fat mass) were measured using the Lunar Prodigy dual x-ray emission absorptiometry scanner. We found strong negative associations between MVPA and fat mass that were unaltered after adjustment for total physical activity. We found a strong negative dose-response association between MVPA and obesity. The odds ratio for obesity in adjusted models between top and the bottom quintiles of minutes of MVPA was 0.03 (95% confidence interval [CI] 0.01-0.13, p-value for trend < 0.0001) in boys and 0.36 (95% CI 0.17-0.74, p-value for trend = 0.006) in girls. Conclusions We demonstrated a strong graded inverse association between physical activity and obesity that was stronger in boys. Our data suggest that higher intensity physical activity may be more important than total activity
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