3,693 research outputs found

    Photon momentum transfer plane for asteroid, meteoroid, and comet orbit shaping

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    A spacecraft docks with a spinning and/or rotating asteroid, meteoroid, comet, or other space object, utilizing a tether shaped in a loop and utilizing subvehicles appropriately to control loop instabilities. The loop is positioned about a portion of the asteroid and retracted thereby docking the spacecraft to the asteroid, meteoroid, comet, or other space object. A deployable rigidized, photon momentum transfer plane of sufficient thickness may then be inflated and filled with foam. This plane has a reflective surface that assists in generating a larger momentum from impinging photons. This plane may also be moved relative to the spacecraft to alter the forces acting on it, and thus on the asteroid, meteoroid, comet, or other space object to which it is attached. In general, these forces may be utilized, over time, to alter the orbits of asteroids, meteoroids, comets, or other space objects. Sensors and communication equipment may be utilized to allow remote operation of the rigidized, photon momentum transfer plane and tether

    Streaming, Distributed Variational Inference for Bayesian Nonparametrics

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    This paper presents a methodology for creating streaming, distributed inference algorithms for Bayesian nonparametric (BNP) models. In the proposed framework, processing nodes receive a sequence of data minibatches, compute a variational posterior for each, and make asynchronous streaming updates to a central model. In contrast to previous algorithms, the proposed framework is truly streaming, distributed, asynchronous, learning-rate-free, and truncation-free. The key challenge in developing the framework, arising from the fact that BNP models do not impose an inherent ordering on their components, is finding the correspondence between minibatch and central BNP posterior components before performing each update. To address this, the paper develops a combinatorial optimization problem over component correspondences, and provides an efficient solution technique. The paper concludes with an application of the methodology to the DP mixture model, with experimental results demonstrating its practical scalability and performance.Comment: This paper was presented at NIPS 2015. Please use the following BibTeX citation: @inproceedings{Campbell15_NIPS, Author = {Trevor Campbell and Julian Straub and John W. {Fisher III} and Jonathan P. How}, Title = {Streaming, Distributed Variational Inference for Bayesian Nonparametrics}, Booktitle = {Advances in Neural Information Processing Systems (NIPS)}, Year = {2015}

    Perspectives of healthcare providers on the nutritional management of patients on haemodialysis in Australia: An interview study

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    Objective To describe the perspectives of healthcare providers on the nutritional management of patients on haemodialysis, which may inform strategies for improving patient-centred nutritional care. Design Face-to-face semistructured interviews were conducted until data saturation, and thematic analysis based on principles of grounded theory. Setting 21 haemodialysis centres across Australia. Participants 42 haemodialysis clinicians (nephrologists and nephrology trainees (15), nurses (12) and dietitians (15)) were purposively sampled to obtain a range of demographic characteristics and clinical experiences. Results Six themes were identified: responding to changing clinical status (individualising strategies to patient needs, prioritising acute events, adapting guidelines), integrating patient circumstances (assimilating life priorities, access and affordability), delineating specialty roles in collaborative structures (shared and cohesive care, pivotal role of dietary expertise, facilitating access to nutritional care, perpetuating conflicting advice and patient confusion, devaluing nutritional specialty), empowerment for behaviour change (enabling comprehension of complexities, building autonomy and ownership, developing self-efficacy through engagement, tailoring self-management strategies), initiating and sustaining motivation (encountering motivational hurdles, empathy for confronting life changes, fostering non-judgemental relationships, emphasising symptomatic and tangible benefits, harnessing support networks), and organisational and staffing barriers (staffing shortfalls, readdressing system inefficiencies). Conclusions Organisational support with collaborative multidisciplinary teams and individualised patient care were seen as necessary for developing positive patient-clinician relationships, delivering consistent nutrition advice, and building and sustaining patient motivation to enable change in dietary behaviour. Improving service delivery and developing and delivering targeted, multifaceted self-management interventions may enhance current nutritional management of patients on haemodialysis

    Aerospace Laser Ignition/Ablation Variable High Precision Thruster

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    A laser ignition/ablation propulsion system that captures the advantages of both liquid and solid propulsion. A reel system is used to move a propellant tape containing a plurality of propellant material targets through an ignition chamber. When a propellant target is in the ignition chamber, a laser beam from a laser positioned above the ignition chamber strikes the propellant target, igniting the propellant material and resulting in a thrust impulse. The propellant tape is advanced, carrying another propellant target into the ignition chamber. The propellant tape and ignition chamber are designed to ensure that each ignition event is isolated from the remaining propellant targets. Thrust and specific impulse may by precisely controlled by varying the synchronized propellant tape/laser speed. The laser ignition/ablation propulsion system may be scaled for use in small and large applications

    Prolonged ventilation in thyroid storm

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    Thyroid storm (crisis) is uncommon but may be life threatening and is recognised by an exaggeration of the clinical features of thyrotoxicosis. Proximal myopathy is a well recognised presenting feature of Graves disease. Respiratory muscle weakness may also commonly occur in thyrotoxicosis but is often undiagnosed. We report a case of thyroid storm with rapid atrial fibrillation, severe agitation and extreme widespread muscle weakness. The respiratory muscles were so compromised that a respiratory arrest occurred. Ventilation was required for 7 weeks until full recovery occurred. </jats:p

    Impact of Ground Water Depletion on the Mesquite Community at Edwards Air Force Base, Western Mojave Desert, California

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    Edwards Air Force Base (EAFB) provides a habitat refugium for mesquite woodlands in the western Mojave Desert of the Antelope Valley. Although many mesquite communities in the arid southwest are considered invasive as they reduce the extent of grazing lands, the community at EAFB is composed primarily of large, widely spaced trees that provide food and shelter for local wildlife species and recreational opportunities for base personnel. Unfortunately, the range of these mesquite trees appears to be contracting as mature and old individuals dominate the community. Although anecdotal evidence suggests that the fall in the local groundwater table is responsible for the decline of the mesquite community at EAFB, no research has been carried out to confirm this. Our results corroborate the hypothesis that the groundwater table at EAFB has declined in the second half of the 20th century and that the area of the mesquite community is diminishing. Although the mesquite community expanded vigorously from 1956 to 1968, it contracted considerably from 1984 to 2000. The evidence for this observed decline is reinforced by the results of the age-class analysis as the community in 2003 is made up largely of mature, old, dying and dead trees. Few saplings (older than 2 years) and no new seedlings (1–2 years) are present in the study sites, suggesting that the mesquite community may not be able to replenish itself

    Dystroglycan Overexpression in Vivo Alters Acetylcholine Receptor Aggregation at the Neuromuscular Junction

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    AbstractDystroglycan is a member of the transmembrane dystrophin glycoprotein complex in muscle that binds to the synapse-organizing molecule agrin. Dystroglycan binding and AChR aggregation are mediated by two separate domains of agrin. To test whether dystroglycan plays a role in receptor aggregation at the neuromuscular junction, we overexpressed it by injecting rabbit dystroglycan RNA into one- or two-celled Xenopus embryos. We measured AChR aggregation in myotomes by labeling them with rhodamine–α-bungarotoxin followed by confocal microscopy and image analysis. Dystroglycan overexpression decreased AChR aggregation at the neuromuscular junction. This result is consistent with dystroglycan competition for agrin without signaling AChR aggregation. It also supports the hypothesis that dystroglycan is not the myotube-associated specificity component, (MASC) a putative coreceptor needed for agrin to activate muscle-specific kinase (MuSK) and signal AChR aggregation. Dystroglycan was distributed along the surface of muscle membranes, but was concentrated at the ends of myotomes, where AChRs normally aggregate at synapses. Overexpressed dystroglycan altered AChR aggregation in a rostral–caudal gradient, consistent with the sequential development of neuromuscular synapses along the embryo. Increasing concentrations of dystroglycan RNA did not further decrease AChR aggregation, but decreased embryo survival. Development often stopped during gastrulation, suggesting an essential, nonsynaptic role of dystroglycan during this early period of development

    Dietary patterns for adults with chronic kidney disease

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    This is the protocol for a review and there is no abstract. The objectives are as follows: This review will evaluate the benefits and harms of dietary patterns among adults with CKD (any stage including people with end-stage kidney disease (ESKD) treated with dialysis, transplantation or supportive care)

    Colubrid snake

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    20 p. : ill., map ; 26 cm.Includes bibliographical references (p. 19-20)."Rhadinophanes, new genus, is erected for a small colubrid snake from high montane forest (~2750 m.) on Cerro Teótepec, in the Sierra Madre del Sur of central Guerrero, Mexico. The characteristics of Rhadinophanes monticola, new species, include a mottled linear pattern, enlarged, ungrooved rear maxillary teeth, and smooth dorsal scales with paired apical pits, in 19-19-17 rows. The hemipenis has a centripetal sulcus spermaticus and is distinctly bilobed, with each lobe being spinose basally and individually calyculate and capitate distally. Rhadinophanes monticola resembles snakes of the genera Rhadinaea and Coniophanes, but it is comparatively primitive in hemipenial structure and in several other relevant characters. Although Rhadinophanes might represent the plesiomorphic sister group of Rhadinaea and Coniophanes, the monophyly of these phenotypically similar snakes could not be demonstrated. In contrast, a sister-group relationship is corroborated for Rhadinophanes and the very dissimilar Tantalophis, on the basis of unusual hemipenial features judged to be synapomorphies. The phyletic position of Rhadinophanes and Tantalophis to other genera is uncertain, although similarity can be found to such diverse groups as Rhadinaea-Coniophanes and Leptodeira-Cryophis of Middle America, and with various alsophiine colubrids, which occur widely in the American mainland, West Indies, and Galapagos. The hemipenes of Rhadinophanes and Tantalophis are reminiscent of the alsophiine type, although there seems to be fundamental disparity in several characters, including the synapomorphic features that affirm the monophyly of these two otherwise divergent genera"--P. [1]
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