3,237 research outputs found

    Determining the effects of cattle grazing treatments on Yosemite toads (Anaxyrus [=Bufo] canorus) in montane meadows.

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    Amphibians are experiencing a precipitous global decline, and population stability on public lands with multiple uses is a key concern for managers. In the Sierra Nevada Mountains (California, USA), managers have specifically identified livestock grazing as an activity that may negatively affect Yosemite toads due to the potential overlap of grazing with toad habitat. Grazing exclusion from Yosemite toad breeding and rearing areas and/or entire meadows have been proposed as possible management actions to alleviate the possible impact of cattle on this species. The primary objective of this study was to determine if different fencing treatments affect Yosemite toad populations. We specifically examined the effect of three fencing treatments on Yosemite toad breeding pool occupancy, tadpoles, and young of the year (YOY). Our hypothesis was that over the course of treatment implementation (2006 through 2010), Yosemite toad breeding pool occupancy and early life stage densities would increase within two fencing treatments relative to actively grazed meadows due to beneficial changes to habitat quality in the absence of grazing. Our results did not support our hypothesis, and showed no benefit to Yosemite toad presence or early life stages in fenced or partially fenced meadows compared to standard USDA Forest Service grazing levels. We found substantial Yosemite toad variation by both meadow and year. This variation was influenced by meadow wetness, with water table depth significant in both the tadpole and YOY models

    Composites Materials and Manufacturing Technologies for Space Applications

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    Composite materials offer significant advantages in space applications. Weight reduction is imperative for deep space systems. However, the pathway to deployment of composites alternatives is problematic. Improvements in the materials and processes are needed, and extensive testing is required to validate the performance, qualify the materials and processes, and certify components. Addressing these challenges could lead to the confident adoption of composites in space applications and provide spin-off technical capabilities for the aerospace and other industries. To address the issues associated with composites applications in space systems, NASA sponsored a Technical Interchange Meeting (TIM) entitled, "Composites Materials and Manufacturing Technologies for Space Applications," the proceedings of which are summarized in this Conference Publication. The NASA Space Technology Mission Directorate and the Game Changing Program chartered the meeting. The meeting was hosted by the National Center for Advanced Manufacturing (NCAM)-a public/private partnership between NASA, the State of Louisiana, Louisiana State University, industry, and academia, in association with the American Composites Manufacturers Association. The Louisiana Center for Manufacturing Sciences served as the coordinator for the TIM

    Heating mechanisms in radio frequency driven ultracold plasmas

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    Several mechanisms by which an external electromagnetic field influences the temperature of a plasma are studied analytically and specialized to the system of an ultracold plasma (UCP) driven by a uniform radio frequency (RF) field. Heating through collisional absorption is reviewed and applied to UCPs. Furthermore, it is shown that the RF field modifies the three body recombination process by ionizing electrons from intermediate high-lying Rydberg states and upshifting the continuum threshold, resulting in a suppression of three body recombination. Heating through collisionless absorption associated with the finite plasma size is calculated in detail, revealing a temperature threshold below which collisionless absorption is ineffective.Comment: 14 pages, 7 figure

    Pressure Induced Hydration Dynamics of Membranes

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    Pressure-jump initiated time-resolved x-ray diffraction studies of dynamics of the hydration of the hexagonal phase in biological membranes show that (i) the relaxation of the unit cell spacing is non-exponential in time; (ii) the Bragg peaks shift smoothly to their final positions without significant broadening or loss in crystalline order. This suggests that the hydration is not diffusion limited but occurs via a rather homogeneous swelling of the whole lattice, described by power law kinetics with an exponent β=1.3±0.2 \beta = 1.3 \pm 0.2.Comment: REVTEX 3, 10 pages,3 figures(available on request),#

    K-Rational D-Brane Crystals

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    In this paper the problem of constructing spacetime from string theory is addressed in the context of D-brane physics. It is suggested that the knowledge of discrete configurations of D-branes is sufficient to reconstruct the motivic building blocks of certain Calabi-Yau varieties. The collections of D-branes involved have algebraic base points, leading to the notion of K-arithmetic D-crystals for algebraic number fields K. This idea can be tested for D0-branes in the framework of toroidal compactifications via the conjectures of Birch and Swinnerton-Dyer. For the special class of D0-crystals of Heegner type these conjectures can be interpreted as formulae that relate the canonical Neron-Tate height of the base points of the D-crystals to special values of the motivic L-function at the central point. In simple cases the knowledge of the D-crystals of Heegner type suffices to uniquely determine the geometry.Comment: 36 page

    The Choice Should Be Yours: Diabetes-Related Distress by Insulin Delivery Method for People with Type 1 Diabetes

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    Background: American Diabetes Association (ADA) recommends psychosocial assessment for people with diabetes, including diabetes-related distress. Elevated diabetes-related distress is associated with poor self-management, lower medication adherence, and poorer quality of life. Insulin delivery methods are multiple daily injections (MDI) or continuous subcutaneous insulin infusion (CSII). Because people with type 1 diabetes mellitus (T1DM) require comprehensive insulin therapy to manage blood glucose, we explored the association of insulin delivery methods and diabetes distress in this group. Methods: The U.S. Air Force Diabetes Center of Excellence (DCOE), a specialty clinic for adults who are Military Health System beneficiaries, administers the validated 17-item Diabetes-related Distress Scale (DDS-17) as part of standard care. Patient data were analyzed from June 2015 to August 2016 using SPSS version 22. Patients were free to choose the method of insulin delivery with minimal or no additional cost. Results: There were 203 patients with T1DM who completed the DDS-17 as part of standard care during the time period. Patients were categorized as CSII (57.6%) or MDI (42.4%). Women were significantly more likely to choose MDI over CSII than men (P = 0.003). DDS-17 scores were low in both groups, and there were no significant differences in DDS-17 by insulin delivery method. Furthermore, no significant differences were found in hemoglobin A1c (HbA1c) between CSII (7.9% or 63 mmol/mol) and MDI (8.1% or 65 mmol/mol) users (P = 0.22) and no significant differences in body mass index (BMI) between patients using CSII (M = 28.33 kg/m2) and MDI (28.49 kg/m2) users (P = 0.15). Conclusions: Our study demonstrated that if patients are relatively free to choose the insulin delivery method (minimal or no financial constraints), there were no differences in diabetes distress scores, HbA1c, or BMI between CSII and MDI. Therefore, people with T1DM may benefit from choosing the method of insulin delivery that will enable them to achieve individual goals and manage diabetes-related distress

    Protein multi-scale organization through graph partitioning and robustness analysis: Application to the myosin-myosin light chain interaction

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    Despite the recognized importance of the multi-scale spatio-temporal organization of proteins, most computational tools can only access a limited spectrum of time and spatial scales, thereby ignoring the effects on protein behavior of the intricate coupling between the different scales. Starting from a physico-chemical atomistic network of interactions that encodes the structure of the protein, we introduce a methodology based on multi-scale graph partitioning that can uncover partitions and levels of organization of proteins that span the whole range of scales, revealing biological features occurring at different levels of organization and tracking their effect across scales. Additionally, we introduce a measure of robustness to quantify the relevance of the partitions through the generation of biochemically-motivated surrogate random graph models. We apply the method to four distinct conformations of myosin tail interacting protein, a protein from the molecular motor of the malaria parasite, and study properties that have been experimentally addressed such as the closing mechanism, the presence of conserved clusters, and the identification through computational mutational analysis of key residues for binding.Comment: 13 pages, 7 Postscript figure

    Rotating Superconductors and the London Moment: Thermodynamics versus Microscopics

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    Comparing various microscopic theories of rotating superconductors to the conclusions of thermodynamic considerations, we traced their marked difference to the question of how some thermodynamic quantities (the electrostatic and chemical potentials) are related to more microscopic ones: The electron's the work function, mean-field potential and Fermi energy -- certainly a question of general import. After the correct identification is established, the relativistic correction for the London Moment is shown to vanish, with the obvious contribution from the Fermi velocity being compensated by other contributions such as electrostatics and interactions.Comment: 23 pages 4 fi
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