2,000 research outputs found

    A warped kernel improving robustness in Bayesian optimization via random embeddings

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    This works extends the Random Embedding Bayesian Optimization approach by integrating a warping of the high dimensional subspace within the covariance kernel. The proposed warping, that relies on elementary geometric considerations, allows mitigating the drawbacks of the high extrinsic dimensionality while avoiding the algorithm to evaluate points giving redundant information. It also alleviates constraints on bound selection for the embedded domain, thus improving the robustness, as illustrated with a test case with 25 variables and intrinsic dimension 6

    Adipokine Imbalance in the Pericardial Cavity of Cardiac and Vascular Disease Patients

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    Aim Obesity and especially hypertrophy of epicardial adipose tissue accelerate coronary atherogenesis. We aimed at comparing levels of inflammatory and atherogenic hormones from adipose tissue in the pericardial fluid and circulation of cardiovascular disease patients. Methods and Results Venous plasma (P) and pericardial fluid (PF) were obtained from elective cardiothoracic surgery patients (n = 37). Concentrations of leptin, adipocyte fatty acid-binding protein (AFABP) and adiponectin (APN) were determined by enzyme-linked immunosorbent assays (ELISA). The median concentration of leptin in PF (4.3 (interquartile range: 2.8-9.1) mu g/L) was comparable to that in P (5.9 (2.2-11) mu g/L) and these were significantly correlated to most of the same patient characteristics. The concentration of A-FABP was markedly higher (73 (28-124) versus 8.4 (5.2-14) mu g/L) and that of APN was markedly lower (2.8 (1.7-4.2) versus 13 (7.2-19) mg/L) in PF compared to P. APN in PF was unlike in P not significantly related to age, body mass index, plasma triglycerides or coronary artery disease. PF levels of APN, but not A-FABP, were related to the size of paracardial adipocytes. PF levels of APN and A-FABP were not related to the immunoreactivity of paracardial adipocytes for these proteins. Conclusion In cardiac and vascular disease patients, PF is enriched in A-FABP and poor in APN. This adipokine microenvironment is more likely determined by the heart than by the circulation or paracardial adipose tissue.published_or_final_versio

    Revealing the electronic structure of a carbon nanotube carrying a supercurrent

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    Carbon nanotubes (CNTs) are not intrinsically superconducting but they can carry a supercurrent when connected to superconducting electrodes. This supercurrent is mainly transmitted by discrete entangled electron-hole states confined to the nanotube, called Andreev Bound States (ABS). These states are a key concept in mesoscopic superconductivity as they provide a universal description of Josephson-like effects in quantum-coherent nanostructures (e.g. molecules, nanowires, magnetic or normal metallic layers) connected to superconducting leads. We report here the first tunneling spectroscopy of individually resolved ABS, in a nanotube-superconductor device. Analyzing the evolution of the ABS spectrum with a gate voltage, we show that the ABS arise from the discrete electronic levels of the molecule and that they reveal detailed information about the energies of these levels, their relative spin orientation and the coupling to the leads. Such measurements hence constitute a powerful new spectroscopic technique capable of elucidating the electronic structure of CNT-based devices, including those with well-coupled leads. This is relevant for conventional applications (e.g. superconducting or normal transistors, SQUIDs) and quantum information processing (e.g. entangled electron pairs generation, ABS-based qubits). Finally, our device is a new type of dc-measurable SQUID

    Energy cost and return for hunting in African wild dogs and Cheetahs

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    African wild dogs (Lycaon pictus) are reported to hunt with energetically costly long chase distances. We used high-resolution GPS and inertial technology to record 1,119 high-speed chases of all members of a pack of six adult African wild dogs in northern Botswana. Dogs performed multiple short, high-speed, mostly unsuccessful chases to capture prey, while cheetahs (Acinonyx jubatus) undertook even shorter, higher-speed hunts. We used an energy balance model to show that the energy return from group hunting and feeding substantially outweighs the cost of multiple short chases, which indicates that African wild dogs are more energetically robust than previously believed. Comparison with cheetah illustrates the trade-off between sheer athleticism and high individual kill rate characteristic of cheetahs, and the energetic robustness of frequent opportunistic group hunting and feeding by African wild dogs

    Psychosocial issues of women with type 1 diabetes transitioning to motherhood: a structured literature review

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    BACKGROUND: Life transitions often involve complex decisions, challenges and changes that affect diabetes management. Transition to motherhood is a major life event accompanied by increased risk that the pregnancy will lead to or accelerate existing diabetes-related complications, as well as risk of adverse pregnancy outcomes, all of which inevitably increase anxiety. The frequency of hyperglycaemia and hypoglycaemia often increases during pregnancy, which causes concern for the health and physical well-being of the mother and unborn child. This review aimed to examine the experiences of women with T1DM focusing on the pregnancy and postnatal phases of their transition to motherhood. METHODS: The structured literature review comprised a comprehensive search strategy identifying primary studies published in English between 1990-2012. Standard literature databases were searched along with the contents of diabetes-specific journals. Reference lists of included studies were checked. Search terms included: 'diabetes', 'type 1', 'pregnancy', 'motherhood', 'transition', 'social support', 'quality of life' and 'psychological well-being'. RESULT: Of 112 abstracts returned, 62 articles were reviewed in full-text, and 16 met the inclusion criteria. There was a high level of diversity among these studies but three common key themes were identified. They related to physical (maternal and fetal) well-being, psychological well-being and social environment. The results were synthesized narratively. CONCLUSION: Women with type 1 diabetes experience a variety of psychosocial issues in their transition to motherhood: increased levels of anxiety, diabetes-related distress, guilt, a sense of disconnectedness from health professionals, and a focus on medicalisation of pregnancy rather than the positive transition to motherhood. A trusting relationship with health professionals, sharing experiences with other women with diabetes, active social support, shared decision and responsibilities for diabetes management assisted the women to make a positive transition. Health professionals can promote a positive transition to motherhood by proactively supporting women with T1DM in informed decision-making, by facilitating communication within the healthcare team and co-ordinating care for women with type 1 diabetes transitioning to motherhood

    Search For Heavy Pointlike Dirac Monopoles

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    We have searched for central production of a pair of photons with high transverse energies in ppˉp\bar p collisions at s=1.8\sqrt{s} = 1.8 TeV using 70pb170 pb^{-1} of data collected with the D\O detector at the Fermilab Tevatron in 1994--1996. If they exist, virtual heavy pointlike Dirac monopoles could rescatter pairs of nearly real photons into this final state via a box diagram. We observe no excess of events above background, and set lower 95% C.L. limits of 610,870,or1580GeV/c2610, 870, or 1580 GeV/c^2 on the mass of a spin 0, 1/2, or 1 Dirac monopole.Comment: 12 pages, 4 figure

    Assessing the impact of a health intervention via user-generated Internet content

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    Assessing the effect of a health-oriented intervention by traditional epidemiological methods is commonly based only on population segments that use healthcare services. Here we introduce a complementary framework for evaluating the impact of a targeted intervention, such as a vaccination campaign against an infectious disease, through a statistical analysis of user-generated content submitted on web platforms. Using supervised learning, we derive a nonlinear regression model for estimating the prevalence of a health event in a population from Internet data. This model is applied to identify control location groups that correlate historically with the areas, where a specific intervention campaign has taken place. We then determine the impact of the intervention by inferring a projection of the disease rates that could have emerged in the absence of a campaign. Our case study focuses on the influenza vaccination program that was launched in England during the 2013/14 season, and our observations consist of millions of geo-located search queries to the Bing search engine and posts on Twitter. The impact estimates derived from the application of the proposed statistical framework support conventional assessments of the campaign

    Imaging Oxygen Distribution in Marine Sediments. The Importance of Bioturbation and Sediment Heterogeneity

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    The influence of sediment oxygen heterogeneity, due to bioturbation, on diffusive oxygen flux was investigated. Laboratory experiments were carried out with 3 macrobenthic species presenting different bioturbation behaviour patterns:the polychaetes Nereis diversicolor and Nereis virens, both constructing ventilated galleries in the sediment column, and the gastropod Cyclope neritea, a burrowing species which does not build any structure. Oxygen two-dimensional distribution in sediments was quantified by means of the optical planar optode technique. Diffusive oxygen fluxes (mean and integrated) and a variability index were calculated on the captured oxygen images. All species increased sediment oxygen heterogeneity compared to the controls without animals. This was particularly noticeable with the polychaetes because of the construction of more or less complex burrows. Integrated diffusive oxygen flux increased with oxygen heterogeneity due to the production of interface available for solute exchanges between overlying water and sediments. This work shows that sediment heterogeneity is an important feature of the control of oxygen exchanges at the sediment–water interface
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