9,588 research outputs found

    The Blood Ontology: An ontology in the domain of hematology

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    Despite the importance of human blood to clinical practice and research, hematology and blood transfusion data remain scattered throughout a range of disparate sources. This lack of systematization concerning the use and definition of terms poses problems for physicians and biomedical professionals. We are introducing here the Blood Ontology, an ongoing initiative designed to serve as a controlled vocabulary for use in organizing information about blood. The paper describes the scope of the Blood Ontology, its stage of development and some of its anticipated uses

    Nanograin VO<inf>2</inf> in the metal phase: A plasmonic system with falling dc resistivity as temperature rises

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    Thin films of vanadium dioxide with grain sizes smaller than 60nm have a metallic phase with excellent plasmonic response, but their dc resistivity falls as temperature rises to values well above the metal-insulator transition. At the transition optical switching is complete, but the switch in dc resistance is incomplete. In the metallic phase, nanograin and large grain samples have similar values of both plasma frequency and relaxation rate. However, plasmonic response in nanograins is stronger due to the absence of a low energy interband transition found in large grain films. Conductivity rises with thermal activation energy of 108meV, which is well below that in the semiconductor phase. Possible mechanisms for 'non-metal-like' dc behaviour in this plasmonic system are briefly discussed. They include fluctuations, which are coherent in nanograins but incoherent for larger grains. Nanoscale systems seem preferable for optical switching applications and large grain structures for dc switching work. © IOP Publishing Ltd

    The apparent optical indices of spongy nanoporous gold

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    Very thin spongy nanoporous gold films have a unique nanostructure and hence unusual properties. Our interest in these materials is also due to their wide range of potential application (1,2). An optical study for such nanostructured films is of fundamental interest for understanding how light interacts with such a spongy nanoporous structure. In general the gold either percolates or is very closely packed. This surface plasmons, and surface plasmon resonant effects, are expected to play a key role given the large surface area of metal and the metal backbone of the nanostructure. The ropological complexity of the nano-void network is also expected to be a major influence. The optical response has, for a metal system, quite unusual dispersion relations for the effective complex refractive index components n*, k*. Once these are better understood new optical engineering possibilities arise. We are not aware of any optical studies for spongy metal film nanostructures apart from a brief preliminary report of our own on one such film 93) whose nanstructure was different to the spongy nanoporous films presented here. We check the internal consistency and physical accpetability of the results with a Kramers-Kronig analysis of the spectrumn of n*, k* values, because of their unusual spectral character

    Bioinformatics advances in saliva diagnostics

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    There is a need recognized by the National Institute of Dental & Craniofacial Research and the National Cancer Institute to advance basic, translational and clinical saliva research. The goal of the Salivaomics Knowledge Base (SKB) is to create a data management system and web resource constructed to support human salivaomics research. To maximize the utility of the SKB for retrieval, integration and analysis of data, we have developed the Saliva Ontology and SDxMart. This article reviews the informatics advances in saliva diagnostics made possible by the Saliva Ontology and SDxMart

    Saliva Ontology: An ontology-based framework for a Salivaomics Knowledge Base

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    <p>Abstract</p> <p>Background</p> <p>The Salivaomics Knowledge Base (SKB) is designed to serve as a computational infrastructure that can permit global exploration and utilization of data and information relevant to salivaomics. SKB is created by aligning (1) the saliva biomarker discovery and validation resources at UCLA with (2) the ontology resources developed by the OBO (Open Biomedical Ontologies) Foundry, including a new Saliva Ontology (SALO).</p> <p>Results</p> <p>We define the Saliva Ontology (SALO; <url>http://www.skb.ucla.edu/SALO/</url>) as a consensus-based controlled vocabulary of terms and relations dedicated to the salivaomics domain and to saliva-related diagnostics following the principles of the OBO (Open Biomedical Ontologies) Foundry.</p> <p>Conclusions</p> <p>The Saliva Ontology is an ongoing exploratory initiative. The ontology will be used to facilitate salivaomics data retrieval and integration across multiple fields of research together with data analysis and data mining. The ontology will be tested through its ability to serve the annotation ('tagging') of a representative corpus of salivaomics research literature that is to be incorporated into the SKB.</p

    Bulk and surface plasmons in highly nanoporous gold films

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    The far field plasmonic behaviour of nanoporous gold films with void densities ranging from 60% to 90% has been investigated and modelled. These layers have good dc conductivity and quite different nanostructure to traditional porous layers in which the metal percolates. Our gold films with void density f above 70% have high thermal emittance for a conductor at their thicknesses and their flat spectral response at visible and near infrared wavelengths is not metal like. We derive effective optical constants which become plasmonic at wavelengths between 1.8 and 4 νm for f from 72 to 87%. This onset is much longer than that in bulk gold. For void densities below 70% the onset of plasmonic behaviour is much closer to the dense material. A simple test is implemented to test for surface plasmon polaritons (SPPs) under illumination. The more porous films show no evidence of SPP, while the less porous films display weak evidence. Thus by tailoring void content in these nanostructures we can tailor the onset of effective plasmonic response across a wide range from 0.8 to 4 νm and emittance from around 0.9 down to low values. An effective uniform metal response is thus found in the presence of surface nanostructure without the interface absorption found in dense gold layers with structured surfaces. © 2007 IOP Publishing Ltd

    Ribosomal S6K1 in POMC and AgRP Neurons Regulates Glucose Homeostasis but Not Feeding Behavior in Mice.

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    SummaryHypothalamic ribosomal S6K1 has been suggested as a point of convergence for hormonal and nutrient signals in the regulation of feeding behavior, bodyweight, and glucose metabolism. However, the long-term effects of manipulating hypothalamic S6K1 signaling on energy homeostasis and the cellular mechanisms underlying these roles are unclear. We therefore inactivated S6K1 in pro-opiomelanocortin (POMC) and agouti-related protein (AgRP) neurons, key regulators of energy homeostasis, but in contrast to the current view, we found no evidence that S6K1 regulates food intake and bodyweight. In contrast, S6K1 signaling in POMC neurons regulated hepatic glucose production and peripheral lipid metabolism and modulated neuronal excitability. S6K1 signaling in AgRP neurons regulated skeletal muscle insulin sensitivity and was required for glucose sensing by these neurons. Our findings suggest that S6K1 signaling is not a general integrator of energy homeostasis in the mediobasal hypothalamus but has distinct roles in the regulation of glucose homeostasis by POMC and AgRP neurons

    Penguin decays of B mesons

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    Penguin, or loop, decays of B mesons induce effective flavor-changing neutral currents, which are forbidden at tree level in the Standard Model. These decays give special insight into the CKM matrix and are sensitive to non-standard model effects. In this review, we give a historical and theoretical introduction to penguins and a description of the various types of penguin processes: electromagnetic, electroweak, and gluonic. We review the experimental searches for penguin decays, including the measurements of the electromagnetic penguins b -> s gamma and B -> K* gamma and gluonic penguins B -> K pi, B+ -> omega K+ and B -> eta' K, and their implications for the Standard Model and New Physics. We conclude by exploring the future prospects for penguin physics.Comment: 49 pages, LATEX, 30 embedded figures, submitted to Annual Reviews of Nuclear and Particle Scienc
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