4,473 research outputs found

    Anelastic dynamo models with variable conductivity - a model for Saturn?

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    Rotating magnetic shallow water waves in a sphere

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    Saturn’s axisymmetric field: A low Rm nonlinear analysis

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    Excitation mechanism of waves in the Earth's core

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    Thermoregulatory capabilities of the woodland dormouse, Graphiurus murinus

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    The woodland dormouse, Graphiurus murinus, in common with many other small rodents, enters torpor under conditions of food deprivation and low temperatures. Its thermoregulatory capabilities under more favourable conditions, however, have not been investigated. We measured metabolism and thermoregulation in woodland dormice acclimated to long-day length, moderate temperature and abundant food over a temperature range (Ta) of approximately 5–37°C. The thermal neutral zone for this species lay between 29 and 35°C. Estimated resting metabolic rate (RMR) within this range averaged 21.10 ± 3.28 J g-1 h-1. Below 29°C energy expenditure increased with a decrease in Ta, with a maximum value of 90.76 J g-1 h-1 measured at 6°C. Both evaporative water loss (EWL) and thermal conductance (C) were minimal and independent of Tsub>a between 5 and 32°C but increased above the thermal neutral zone, maximum EWL and C being 6.7 mg g-1 h-1 (79% of metabolic heat production) and 19.74 J g-1 h-1 °C-1 respectively, at 37.3°C. Thermal conductance and RMR of G. murinus were approximately 48% and 30% below predicted for rodents of equivalent mass, respectively. This pattern is consistent with that suggested for warm-temperate arboreal rodents. Although body temperature (Tb) was labile and was significantly related to Ta over the temperature range investigated, dormice maintained Tb s between 34 and 38°C using typical thermoregulatory responses that included increased activity at low Ta and postural adjustments and salivating at high Ta. While not as impressive as some rodent species, under favourable conditions G. murinus is a competent thermoregulator and torpor in the species is facultative

    Efficient measurements, purification, and bounds on the mutual information

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    When a measurement is made on a quantum system in which classical information is encoded, the measurement reduces the observers average Shannon entropy for the encoding ensemble. This reduction, being the {\em mutual information}, is always non-negative. For efficient measurements the state is also purified; that is, on average, the observers von Neumann entropy for the state of the system is also reduced by a non-negative amount. Here we point out that by re-writing a bound derived by Hall [Phys. Rev. A {\bf 55}, 100 (1997)], which is dual to the Holevo bound, one finds that for efficient measurements, the mutual information is bounded by the reduction in the von Neumann entropy. We also show that this result, which provides a physical interpretation for Hall's bound, may be derived directly from the Schumacher-Westmoreland-Wootters theorem [Phys. Rev. Lett. {\bf 76}, 3452 (1996)]. We discuss these bounds, and their relationship to another bound, valid for efficient measurements on pure state ensembles, which involves the subentropy.Comment: 4 pages, Revtex4. v3: rewritten and reinterpreted somewha

    Inductive queries for a drug designing robot scientist

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    It is increasingly clear that machine learning algorithms need to be integrated in an iterative scientific discovery loop, in which data is queried repeatedly by means of inductive queries and where the computer provides guidance to the experiments that are being performed. In this chapter, we summarise several key challenges in achieving this integration of machine learning and data mining algorithms in methods for the discovery of Quantitative Structure Activity Relationships (QSARs). We introduce the concept of a robot scientist, in which all steps of the discovery process are automated; we discuss the representation of molecular data such that knowledge discovery tools can analyse it, and we discuss the adaptation of machine learning and data mining algorithms to guide QSAR experiments

    ISPIDER Central: an integrated database web-server for proteomics

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    Despite the growing volumes of proteomic data, integration of the underlying results remains problematic owing to differences in formats, data captured, protein accessions and services available from the individual repositories. To address this, we present the ISPIDER Central Proteomic Database search (http://www.ispider.manchester.ac.uk/cgi-bin/ProteomicSearch.pl), an integration service offering novel search capabilities over leading, mature, proteomic repositories including PRoteomics IDEntifications database (PRIDE), PepSeeker, PeptideAtlas and the Global Proteome Machine. It enables users to search for proteins and peptides that have been characterised in mass spectrometry-based proteomics experiments from different groups, stored in different databases, and view the collated results with specialist viewers/clients. In order to overcome limitations imposed by the great variability in protein accessions used by individual laboratories, the European Bioinformatics Institute's Protein Identifier Cross-Reference (PICR) service is used to resolve accessions from different sequence repositories. Custom-built clients allow users to view peptide/protein identifications in different contexts from multiple experiments and repositories, as well as integration with the Dasty2 client supporting any annotations available from Distributed Annotation System servers. Further information on the protein hits may also be added via external web services able to take a protein as input. This web server offers the first truly integrated access to proteomics repositories and provides a unique service to biologists interested in mass spectrometry-based proteomics

    Follow-up analysis of federal process of care data reported from three acute care hospitals in rural Appalachia

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    BACKGROUND: This investigation evaluated standardized process of care data collected on selected hospitals serving a remote rural section of westernmost North Carolina. METHODS: Centers for Medicare and Medicaid Services data were analyzed retrospectively for multiple clinical parameters at Fannin Regional Hospital, Murphy Medical Center, and Union General Hospital. Data were analyzed by paired t-test for individual comparisons among the three study hospitals to compare the three facilities with each other, as well as with state and national average for each parameter. RESULTS: Centers for Medicare and Medicaid Services "Hospital Compare" data from 2011 showed Fannin Regional Hospital to have significantly higher composite scores on standardized clinical process of care measures relative to the national average, compared with Murphy Medical Center (P = 0.01) and Union General Hospital (P = 0.01). This difference was noted to persist when Fannin Regional Hospital was compared with Union General Hospital using common state reference data (P = 0.02). When compared with national averages, mean process of care scores reported from Murphy Medical Center and Union General Hospital were both lower but not significantly different (-3.44 versus -6.07, respectively, P = 0.54). CONCLUSION: The range of process of care scores submitted by acute care hospitals in western North Carolina is considerable. Centers for Medicare and Medicaid Services "Hospital Compare" information suggests that process of care measurements at Fannin Regional Hospital are significantly higher than at either Murphy Medical Center or Union General Hospital, relative to state and national benchmarks. Further investigation is needed to determine what impact these differences in process of care may have on hospital volume and/or market share in this region. Additional research is planned to identify process of care trends in this demographic and geographically rural area

    Antarctic Station Based Seasonal Pressure Reconstructions Since 1905, Part 1: Reconstruction Evaluation

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    Seasonal mean Antarctic pressures at 17 stations are reconstructed based on the method of principal component regression, employing midlatitude pressure data as predictors. Several reconstruction methods were performed in order to assess the stability and reliability of the reconstructions obtained, including performing the reconstructions over a shorter 30 year window and withholding the remaining data for an independent validation. Generally, there were small differences between the various approaches, but typically reconstructions conducted on data with the trends still present and over the full period of observations achieved the highest skill. Seasonally, reconstruction skill was high in austral summer across the entire Antarctic continent. Reconstructions that employed gridded pressure data over oceans as well as the observations (here termed “pseudoreconstructions”) also performed remarkably well in austral winter. Spatially, the reconstruction skill was highest near the Antarctic Peninsula in all seasons, and weakest in coastal East Antarctica and the Antarctic Interior during austral spring and autumn; the spatial variability of the skill in part reflects the distance to the nearest midlatitude predictor. Nonetheless, for nearly all seasons and locations the observed trends since 1957 were well captured by the reconstructions, as was the low-frequency decadal-scale variability. These results suggest Antarctic pressure observations can be extended throughout the twentieth century with high confidence, especially in summer, allowing for a more precise understanding of the role and magnitude of natural atmospheric circulation variability across Antarctica
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