1,964 research outputs found

    Determination of population structure and stock composition of chum salmon (Oncorhynchus keta) in Russia determined with microsatellites

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    Variation at 14 microsatellite loci was examined in 34 chum salmon (Oncorhynchus keta) populations from Russia and evaluated for its use in the determination of population structure and stock composition in simulated mixed-stock fishery samples. The genetic differentiation index (Fst) over all populations and loci was 0.017, and individual locus values ranged from 0.003 to 0.054. Regional population structure was observed, and populations from Primorye, Sakhalin Island, and northeast Russia were the most distinct. Microsatellite variation provided evidence of a more fine-scale population structure than those that had previously been demonstrated with other genetic-based markers. Analysis of simulated mixed-stock samples indicated that accurate and precise regional estimates of stock composition were produced when the microsatellites were used to estimate stock compositions. Microsatellites can be used to determine stock composition in geographically separate Russian coastal chum salmon fisheries and provide a greater resolution of stock composition and population structure than that previously provided with other techniques

    Are methodological quality and completeness of reporting associated with citation-based measures of publication impact? A secondary analysis of a systematic review of dementia biomarker studies

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    Objective: To determine whether methodological and reporting quality are associated with surrogate measures of publication impact in the field of dementia biomarker studies. Methods: We assessed dementia biomarker studies included in a previous systematic review in terms of methodological and reporting quality using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) and Standards for Reporting of Diagnostic Accuracy (STARD), respectively. We extracted additional study and journal-related data from each publication to account for factors shown to be associated with impact in previous research. We explored associations between potential determinants and measures of publication impact in univariable and stepwise multivariable linear regression analyses. Outcome measures: We aimed to collect data on four measures of publication impact: two traditional measures—average number of citations per year and 5-year impact factor of the publishing journal and two alternative measures—the Altmetric Attention Score and counts of electronic downloads. Results: The systematic review included 142 studies. Due to limited data, Altmetric Attention Scores and electronic downloads were excluded from the analysis, leaving traditional metrics as the only analysed outcome measures. We found no relationship between QUADAS and traditional metrics. Citation rates were independently associated with 5-year journal impact factor (β=0.42; p<0.001), journal subject area (β=0.39; p<0.001), number of years since publication (β=-0.29; p<0.001) and STARD (β=0.13; p<0.05). Independent determinants of 5-year journal impact factor were citation rates (β=0.45; p<0.001), statement on conflict of interest (β=0.22; p<0.01) and baseline sample size (β=0.15; p<0.05). Conclusions: Citation rates and 5-year journal impact factor appear to measure different dimensions of impact. Citation rates were weakly associated with completeness of reporting, while neither traditional metric was related to methodological rigour. Our results suggest that high publication usage and journal outlet is not a guarantee of quality and readers should critically appraise all papers regardless of presumed impact

    Cavity optoelectromechanical regenerative amplification

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    Cavity optoelectromechanical regenerative amplification is demonstrated. An optical cavity enhances mechanical transduction, allowing sensitive measurement even for heavy oscillators. A 27.3 MHz mechanical mode of a microtoroid was linewidth narrowed to 6.6\pm1.4 mHz, 30 times smaller than previously achieved with radiation pressure driving in such a system. These results may have applications in areas such as ultrasensitive optomechanical mass spectroscopy

    Annual Survey of Virginia Law: Property Law

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    The Supreme Court of Virginia, the United States Court of Appeals for the Fourth Circuit, and the Circuit Court of Fairfax County have decided a number of important property law cases over the past year. Part I of this article discusses the most significant of those cases. Legislation passed by the Virginia General Assembly with respect to property is discussed in Part II of this article

    In situ testing of a satellite or other object prior to development

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    A method and system for testing a test object, such as a satellite, is disclosed. High energy acoustic testing is performed on the object by assembling an acoustical system about the test object rather than transporting the test object to a specially configured acoustic chamber. The acoustic system of the present invention preferably provides and directs acoustic energy directly to the surfaces of the test object rather than providing the test object in a high energy acoustic environment where a substantial amount of the acoustic energy is randomly directed within a chamber having the test object. Additionally, the present invention further provides for mechanical vibration tests concurrently or serially with acoustic testing, wherein the object is not required to be transported

    Rebuilding Afghanistan’s Higher Educational System: Observations from Kabul

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    This paper describes the crucial issues and challenges facing Afghanistan’s universities as they begin the demanding task of rebuilding and restructuring their university system after two decades of war and civil unrest. The setting for this qualitative study is a four-day professional development conference for Afghan university presidents and academic deans sponsored and funded by the United Nations Educational, Scientific and Cultural Organization and the Afghanistan Ministry of Higher Education. Cooperative Studies (an NGO, not-for-profit educational organization located in Kansas City) provided a team of academics to Kabul, Afghanistan, to offer professional development workshops. Using the Grounded Theory Methodology as a theoretical framework for this research, data was derived from interactive sessions, questionnaires, informal dialogue, small group sessions and question and answer sessions; the perspectives of the 39 Afghan academic leaders are presented as they describe the problems facing university administrators in their country today. Findings identify these challenges and center on 1) the lack of autonomy; 2) the need for qualified faculty; 3) concerns regarding students’ access and preparation; and 4) concerns about funding and budget issues. Based on these findings, policy suggestions and recommendations are provided

    Modified Shepard interpolation of gas-surface potential energy surfaces with strict plane group symmetry and translational periodicity

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    A new formulation of modified Shepard interpolation of potential energy surface data for gas-surface reactions has been developed. The approach has been formulated for monoatomic or polyatomic adsorbates interacting with crystalline solid surfaces of any plane group symmetry. The interpolation obeys the two dimensional translational periodicity and plane group symmetry of the solid surface by construction. The interpolation remains continuous and smooth everywhere. The interpolation developed here is suitable for constructing potential energy surfaces by sampling classical trajectories using the Grow procedure. A model function has been used to demonstrate the method, showing the convergence of the classical gas-surface reaction probability

    The lithurgine bees of Australia (Hymenoptera: Megachilidae), with a note on Megachile rotundipennis

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    Austrothurgus Gonzalez & Engel, new genus, is described and figured for three species of lithurgine bees (Megachilidae: Lithurginae: Lithurgini) from Australia. Austrothurgus is distinguished from other Lithurginae by the presence of arolia in males (absent in females), first flagellomere long in both sexes, female facial prominence mostly involving the base of clypeus, and male metabasitarsus with distinct, elevated carina on its inner surface. Austrothurgus malgaru Gonzalez, Engel, & Griswold, new species, from Western Australia is also described and figured. A neotype is designated for Lithurgus dentipes Smith and lectotypes for L. atratus Smith, L. cognatus Smith, and L. rubricatus Smith. The following two new combinations are established: A. cognatus (Smith) and A. rubricatus (Smith). An updated key to the genera of Lithurgini as well as diagnoses, illustrations, and a key to the species occurring in Australia are provided. Taxonomic notes and a new lectotype designation for the Indo-Pacific species Megachile (Eutricharaea) rotundipennis Kirby are also appended

    Profitability of Variable Rate Phosphorus in a Two Crop Rotation

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    The purpose of this study is to examine the profitability of variable rate phosphorus application on a rotation of rice (Oryza sativa) and soybeans (Glycine max) on fields comprised of clay and silt loam soils. Phosphorus was chosen because 1) farmers have recently been advised of the benefit of phosphorus applications on rice as well as soybeans, 2)recommended phosphorus application rates vary greatly between clay and silt loam soils and across rice and soybeans, and 3) the residual effects of phosphorus applications in a crop rotation affect the appropriateness of variable rate technology (VRT). A three phase simulation, regression and mathematical optimization analysis was conducted to determine within a ten year planning horizon the conditions under which the profitability of variable rate phosphorus applications exceeded the profitability of uniform rate technology. Results showed that in general, VRT is not profitable when fields are comprised of only the three studied silt loam soils. However, VRT was found to be profitable in most cases when even small percentages of clay were added to the soil mixin the field. Adoption will likely also be a function off arm size. Farmers earning relatively small returns to VRT on a small area are not as likely to adopt the technology as larger operations with similar per hectare returns
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