2,211 research outputs found

    Managing biomass feedstocks: selection of satellite storage locations for different harvesting systems

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    Biomass feedstocks including switchgrass and corn stover are currently being considered for use in direct combustion systems, and for value-added products such as ethanol. A major roadblock associated with utilization of biomass feedstocks is the high cost of handling and storage due to low bulk density of these feedstocks. A wide variety of existing harvest systems creates logistics difficulties for bioenergy industries. The utilization of herbaceous biomass materials requires low-cost handling systems to collect, store, and transport year round. This then requires selecting the most economical methods from various existing handling systems for loose and baled biomass materials. How these different harvesting systems can be integrated into a cost-effective supply system is a challenge. A method of selecting lowest cost harvest and handling machine system was proposed; the model developed could calculate costs of different systems so as to assist field managers to select the best handling method for every point in a given location of a biorefinery plant. The results of the model calculation can provide users a map which shows the lowest-cost handling scenario for all handling systems analyzed by this program. This result will enable biorefinary industries and landowners to determine the most cost-effective way to harvest, store, and transport biomass materials according to the size of the biorefinery plant

    Differential rates of perinatal maturation of human primary and nonprimary auditory cortex

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    Abstract Primary and nonprimary cerebral cortex mature along different timescales; however, the differences between the rates of maturation of primary and nonprimary cortex are unclear. Cortical maturation can be measured through changes in tissue microstructure detectable by diffusion magnetic resonance imaging (MRI). In this study, diffusion tensor imaging (DTI) was used to characterize the maturation of Heschl’s gyrus (HG), which contains both primary auditory cortex (pAC) and nonprimary auditory cortex (nAC), in 90 preterm infants between 26 and 42 weeks postmenstrual age (PMA). The preterm infants were in different acoustical environments during their hospitalization: 46 in open ward beds and 44 in single rooms. A control group consisted of 15 term-born infants. Diffusion parameters revealed that (1) changes in cortical microstructure that accompany cortical maturation had largely already occurred in pAC by 28 weeks PMA, and (2) rapid changes were taking place in nAC between 26 and 42 weeks PMA. At term equivalent PMA, diffusion parameters for auditory cortex were different between preterm infants and term control infants, reflecting either delayed maturation or injury. No effect of room type was observed. For the preterm group, disturbed maturation of nonprimary (but not primary) auditory cortex was associated with poorer language performance at age two years

    Universal behavior of quantum Green's functions

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    We consider a general one-particle Hamiltonian H = - \Delta_r + u(r) defined in a d-dimensional domain. The object of interest is the time-independent Green function G_z(r,r') = . Recently, in one dimension (1D), the Green's function problem was solved explicitly in inverse form, with diagonal elements of Green's function as prescribed variables. The first aim of this paper is to extract from the 1D inverse solution such information about Green's function which cannot be deduced directly from its definition. Among others, this information involves universal, i.e. u(r)-independent, behavior of Green's function close to the domain boundary. The second aim is to extend the inverse formalism to higher dimensions, especially to 3D, and to derive the universal form of Green's function for various shapes of the confining domain boundary.Comment: 46 pages, the shortened version submitted to J. Math. Phy

    Bose-Einstein condensation in arbitrarily shaped cavities

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    We discuss the phenomenon of Bose-Einstein condensation of an ideal non-relativistic Bose gas in an arbitrarily shaped cavity. The influence of the finite extension of the cavity on all thermodynamical quantities, especially on the critical temperature of the system, is considered. We use two main methods which are shown to be equivalent. The first deals with the partition function as a sum over energy levels and uses a Mellin-Barnes integral representation to extract an asymptotic formula. The second method converts the sum over the energy levels to an integral with a suitable density of states factor obtained from spectral analysis. The application to some simple cavities is discussed.Comment: 10 pages, LaTeX, to appear in Physical Review

    A zeta function approach to the relation between the numbers of symmetry planes and axes of a polytope

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    A derivation of the Ces\`aro-Fedorov relation from the Selberg trace formula on an orbifolded 2-sphere is elaborated and extended to higher dimensions using the known heat-kernel coefficients for manifolds with piecewise-linear boundaries. Several results are obtained that relate the coefficients, bib_i, in the Shephard-Todd polynomial to the geometry of the fundamental domain. For the 3-sphere we show that b4b_4 is given by the ratio of the volume of the fundamental tetrahedron to its Schl\"afli reciprocal.Comment: Plain TeX, 26 pages (eqn. (86) corrected

    The Gap to Fill: Rationale for Rapid Initiation and Optimal Titration of Comprehensive Disease-modifying Medical Therapy for Heart Failure with Reduced Ejection Fraction

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    There are gaps in the use of therapies that save lives and improve quality of life for patients with heart failure with reduced ejection fraction, both in the US and abroad. The evidence is clear that initiation and titration of guideline-directed medical therapy (GDMT) and comprehensive disease-modifying medical therapy (CDMMT) to maximally tolerated doses improves patient-focused outcomes, yet observational data suggest this does not happen. The purpose of this review is to describe the gap in the use of optimal treatment worldwide and discuss the benefits of newer heart failure therapies including angiotensin receptor-neprilysin inhibitors and sodium-glucose cotransporter 2 inhibitors. It will also cover the efficacy and safety of such treatments and provide potential pathways for the initiation and rapid titration of GDMT/CDMMT

    Global Distribution of Omura’s Whales (Balaenoptera omurai) and Assessment of Range-Wide Threats

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    When the Omura’s whale (Balaenoptera omurai) was first described in 2003, it was known from only three locations: the southern Sea of Japan, and the vicinities of the Cocos (Keeling) Islands and Solomon Islands. Work over the following decade suggested a range limited to the eastern Indo-Pacific, but more recent discoveries in the western Indian Ocean and Atlantic Ocean suggested a more widespread range than previously thought. Here we use all available sources of information, including published papers, unpublished reports, and internet-based accounts, substantiated through genetic, morphological, photographic and acoustic documentation, to compile accounts of Omura’s whales globally. Reports increased precipitously since 2015 after publication of the first detailed external description of the species, reflecting the impact of the recently elevated awareness of the species. We report 161 accounts from 95 locales in the waters of 21 range states, and found that the species is widely distributed in primarily tropical and warm-temperate locations. Currently it is known from all ocean basins with the exception of the central and eastern Pacific. The majority of accounts remain in the eastern Indo-Pacific suggesting a potentially recent range expansion from this region. There is a strong tendency toward a coastal and neritic distribution, although there are also several pelagic records. A predominantly near-coastal distribution places Omura’s whale at risk from anthropogenic activities throughout its range, and its tropical distribution in often remote and poorly monitored areas makes adequately documenting and assessing threats challenging. We assess documented threats in light of the reported species’ range, and found threats from, at minimum, ship strikes, fisheries bycatch and entanglement, local directed hunting, petroleum exploration (seismic surveys), and coastal industrial development. Current evidence indicates that at least some populations are non-migratory with local, potentially restricted ranges. Furthermore, there is low genetic diversity documented throughout its global distribution. Given the species may be characterized by small local populations, it may be particularly vulnerable to impacts from existing regional anthropogenic threats. We recommend that focused work be conducted to locate and study local populations, assess potential population isolation, and determine conservation status and specific anthropogenic threats across the species’ range

    EcoEvo-MAPS: An Ecology and Evolution Assessment for Introductory through Advanced Undergraduates

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    A new assessment tool, Ecology and Evolution–Measuring Achievement and Progression in Science or EcoEvo-MAPS, measures student thinking in ecology and evolution during an undergraduate course of study. EcoEvo-MAPS targets foundational concepts in ecology and evolution and uses a novel approach that asks students to evaluate a series of predictions, conclusions, or interpretations as likely or unlikely to be true given a specific scenario. We collected evidence of validity and reliability for EcoEvo-MAPS through an iterative process of faculty review, student interviews, and analyses of assessment data from more than 3000 students at 34 associate’s-, bachelor’s-, master’s-, and doctoral-granting institutions. The 63 likely/unlikely statements range in difficulty and target student understanding of key concepts aligned with the Vision and Change report. This assessment provides departments with a tool to measure student thinking at different time points in the curriculum and provides data that can be used to inform curricular and instructional modifications
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