2,297 research outputs found

    TetraDENSITY. A database of population density estimates in terrestrial vertebrates

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    Motivation: Population density is a key demographic parameter influencing many ecological processes, and macroecology has described both intra- and interspecific patterns of variation. Population density data are expensive to collect and contain many forms of noise and potential bias; these factors have impeded investigation of macroecological patterns, and many hypotheses remain largely unexplored. Population density also represents fundamental information for conservation, because it underlies population dynamics and, ultimately, extinction risk. Here we present TetraDENSITY, an extensive dataset with > 18,000 records of density estimates for terrestrial vertebrates, in order to facilitate new research on this topic. Main types of variable contained: The dataset includes taxonomic information on species, population density estimate, year of data collection, season, coordinates of the locality, locality name, habitat, sampling method and sampling area. Spatial location and grain: Global. Spatial accuracy varies across studies; conservatively, it can be considered at 1°, but for many data it is much finer. Time period and grain: From 1926 to 2017. Temporal accuracy is yearly in most cases, but studies with higher temporal resolution (season, month) are also present. Major taxa and level of measurement: Amphibians in terrestrial phase, reptiles, birds and mammals. Estimates derive from multiple methods, reflecting the study taxon, location and techniques available at the time of density estimation

    Bright Source of Cold Ions for Surface-Electrode Traps

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    We produce large numbers of low-energy ions by photoionization of laser-cooled atoms inside a surface-electrode-based Paul trap. The isotope-selective trap loading rate of 4Ă—1054\times10^{5} Yb+^{+} ions/s exceeds that attained by photoionization (electron impact ionization) of an atomic beam by four (six) orders of magnitude. Traps as shallow as 0.13 eV are easily loaded with this technique. The ions are confined in the same spatial region as the laser-cooled atoms, which will allow the experimental investigation of interactions between cold ions and cold atoms or Bose-Einstein condensates.Comment: Paper submitted to PRL for review on 2/1/0

    Optimal static and dynamic recycling of defective binary devices

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    The binary Defect Combination Problem consists in finding a fully working subset from a given ensemble of imperfect binary components. We determine the typical properties of the model using methods of statistical mechanics, in particular, the region in the parameter space where there is almost surely at least one fully-working subset. Dynamic recycling of a flux of imperfect binary components leads to zero wastage.Comment: 14 pages, 15 figure

    Dynamics of Line-Driven Winds from Disks in Cataclysmic Variables. I. Solution Topology and Wind Geometry

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    We analyze the dynamics of 2-D stationary, line-driven winds from accretion disks in cataclysmic variable stars. The driving force is that of line radiation pressure, in the formalism developed by Castor, Abbott & Klein for O stars. Our main assumption is that wind helical streamlines lie on straight cones. We find that the Euler equation for the disk wind has two eigenvalues, the mass loss rate and the flow tilt angle with the disk. Both are calculated self-consistently. The wind is characterized by two distinct regions, an outer wind launched beyond four white dwarf radii from the rotation axis, and an inner wind launched within this radius. The inner wind is very steep, up to 80 degrees with the disk plane, while the outer wind has a typical tilt of 60 degrees. In both cases the ray dispersion is small. We, therefore, confirm the bi-conical geometry of disk winds as suggested by observations and kinematical modeling. The wind collimation angle appears to be robust and depends only on the disk temperature stratification. The flow critical points lie high above the disk for the inner wind, but close to the disk photosphere for the outer wind. Comparison with existing kinematical and dynamical models is provided. Mass loss rates from the disk as well as wind velocity laws are discussed in a subsequent paper.Comment: 21 pages, 10 Postscript figures; available also from http://www.pa.uky.edu/~shlosman/publ.html. Astrophysical Journal, submitte

    A variational approach for the Quantum Inverse Scattering Method

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    We introduce a variational approach for the Quantum Inverse Scattering Method to exactly solve a class of Hamiltonians via Bethe ansatz methods. We undertake this in a manner which does not rely on any prior knowledge of integrability through the existence of a set of conserved operators. The procedure is conducted in the framework of Hamiltonians describing the crossover between the low-temperature phenomena of superconductivity, in the Bardeen-Cooper-Schrieffer (BCS) theory, and Bose-Einstein condensation (BEC). The Hamiltonians considered describe systems with interacting Cooper pairs and a bosonic degree of freedom. We obtain general exact solvability requirements which include seven subcases which have previously appeared in the literature.Comment: 18 pages, no eps figure

    Local Rice Production Trend Analyses and Consumption in Benue State, Nigeria: 1980 – 2016

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    The research examined local rice production trends and factors inhibiting the consumption of local rice from 1980 to 2016 in Benue State. Primary data were collected with the aid of questionnaire in Benue State, while secondary data were obtained from Benue Agricultural and Rural Development Authority (BNARDA) in 2017. Multistage random sampling method was employed in selecting respondents. Primary data were collected from one hundred and fifty six (156) respondents. Descriptive statistics, Z – test, Growth model and Kendal’s coefficient of concordance were used for the analysis. The results revealed that from 1980 to 2016, a total of 9.5mt of local rice was produced in Benue State. The result also shows that the respondents were all married (99%), with household size of 1 - 10 persons (95%) and mean household size of about 8 persons. The result further indicated that majority of respondents’ attained tertiary school level. The result also shows that the respondents had low income (40.3%).  The mean quantity of local rice production was 257,333.06mt per year. The instantaneous growth trends of local rice production and price were 0.00122 and 0.01103, and compound growth rate as 3.72 and 3.76 respectively. The result also indicated that many of the respondents were above the age of 41 years (49%) with the mean age of 47 and all respondents male. The presence of stones, poor aroma, impure rice and broken grain were some of the factors inhibiting consumption of local rice in Benue State. The study recommended that the policies that focus on increasing growth rate of local rice in Benue State should be intensified. Breeders and Scientists should make effort in breeding rice with aroma. The processors of local rice should use modern processing mills like rice polisher and des-stoners to mill quality local rice that will be acceptable to consumers

    Expression and function of ryanodine receptor related pathways in PCB tolerant Atlantic killifish (Fundulus heteroclitus) from New Bedford Harbor, MA, USA

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    Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Aquatic Toxicology 159 (2015): 156-166, doi:10.1016/j.aquatox.2014.12.017.Atlantic killifish (Fundulus heteroclitus) thrive in New Bedford Harbor (NBH), MA, highly contaminated with polychlorinated biphenyls (PCBs). Resident killifish have evolved tolerance to dioxin-like (DL) PCBs, whose toxic effects through the aryl hydrocarbon receptor (AhR) are well studied. In NBH, non-dioxin like PCBs (NDL PCBs), which lack activity toward the AhR, vastly exceed levels of DL congeners yet how killifish counter NDL toxic effects has not been explored. In mammals and fish, NDL PCBs are potent activators of ryanodine receptors (RyR), Ca2+ release channels necessary for a vast array of physiological processes. In the current study we compared the expression and function of RyR related pathways in NBH killifish with killifish from the reference site at Scorton Creek (SC, MA). Relative to the SC fish, adults from NBH displayed increased levels of skeletal muscle RyR1 protein, and increased levels of FK506-binding protein 12 kDa (FKBP12), an accessory protein essential for NDL PCB-triggered changes in RyR channel function. In accordance with increased RyR1 levels, NBH killifish displayed increased maximal ligand binding, increased maximal response to Ca2+ activation and increased maximal response to activation by the NDL PCB congener PCB 95. Compared to SC, NBH embryos and larvae had increased levels of mtor and ryr2 transcripts at multiple stages of development, and generations, while levels of serca2 were decreased at 9 days post-fertilization in the F1 and F2 generations. These findings suggest that there are compensatory and heritable changes in RyR mediated Ca2+ signaling proteins or potential signaling partners in NBH killifish.Funding was provided through the NIEHS Superfund Research Program UC Davis (INP and EBF; P42-ES004699) and Boston University (JJS and JVG; P42-ES007381). Support was supplied via the UC Davis NHLBI Training Grant (T32-HL086350, EBF). Additional support came from NIEHS 1R01-ES014901, 1R01-ES017425, the UC Davis Center for Children’s Environmental Health (1P01-ES011269, U.S. Environmental Protection Agency Grant 8354320), and an unrestricted JB Johnson Foundation gift grant.2015-12-1

    Cyclometalation of lanthanum(iii) based MOF for catalytic hydrogenation of carbon dioxide to formate

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    The hydrogenation of carbon dioxide (CO2) to formic acid is of great importance due to its useful properties in the chemical industry. In this work, we have prepared a novel metal-organic framework (MOF), JMS-1, using bipyridyl dicarboxylate linkers, with molecular formula [La2(bpdc)3(DMF)3]n. Network analysis of JMS-1 revealed a new 7-connected topology (zaz). The MOF backbone of the activated phase (JMS-1a) was functionalized by cyclometalation using [RuCl2(p-cymene)]2 to produce Ru(ii)@JMS-1a. Both JMS-1a and Ru(ii)@JMS-1a were able to convert CO2 in the presence of hydrogen to formate. Ru(ii)@JMS-1a displayed outstanding conversion evidenced by a yield of 98% of formate under optimized conditions of total pressure 50 bar (CO2/H2 = 1 : 4, temperature 110 \ub0C, time 24 h, 5 mmol KOH, 8 mL ethanol). This work is significant in providing new strategies of incorporating active catalytic centres in MOFs for efficient and selective conversion of CO2 to formate

    Development and evaluation of an emulsion containing lycopene for combating acceleration of skin aging

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    Licopeno é um carotenóide com potente atividade antioxidante encontrado em grande quantidade no tomate e usado no combate a diversas doenças como doenças cardiovasculares e diferentes tipos de cânceres, incluindo o câncer de próstata. O objetivo desse trabalho foi desenvolver uma emulsão contendo extrato de licopeno obtido do tomate salada e avaliar a citotoxicidade do extrato, a estabilidade, o comportamento reológico, atividade antioxidante e permeação do fitocosmético. O cosmético foi desenvolvido utilizando fase oleosa contendo derivados de Karité e submetido à avaliação da estabilidade físico-química, espalhabilidade, análise térmica, comportamento reológico, qualidade microbiológica, citotoxicidade, atividade antioxidante e testes de permeação e retenção cutânea. Os resultados demonstraram que o fitocosmético é estável, apresenta comportamento reológico desejável para uma formulação tópica e é um produto promissor para ser utilizado no combate à aceleração do envelhecimento cutâneo.Lycopene, a carotenoid and potent antioxidant is found in large quantities in tomatoes. Lycopene combats diseases, such as cardiovascular disease and different types of cancer, including prostate cancer. However, its topical use in emulsion form for the combat of skin aging is under-explored. The aim of the present study was to develop an emulsion containing lycopene extracted from salad tomatoes and evaluate its cytotoxicity, stability, rheological behavior, antioxidant activity and phytocosmetic permeation. The developed cosmetic comprised an oil phase made up of shea derivatives and was evaluated in terms of its physiochemical stability, spreadability, thermal analysis, rheological behavior, microbiological quality, cytotoxicity, antioxidant activity, cutaneous permeation and retention. The results demonstrate that this phytocosmetic is stable, exhibits satisfactory rheological behavior for a topical formula and is a promising product for combating skin aging
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