4,684 research outputs found

    Fundamental Limits of "Ankylography" due to Dimensional Deficiency

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    Single-shot diffractive imaging of truly 3D structures suffers from a dimensional deficiency and does not scale. The applicability of "ankylography" is limited to objects that are small-sized in at least one dimension or that are essentially 2D otherwise.Comment: 2 pages, no figur

    D-brane Construction of the 5D NHEK Dual

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    Extremal but non-supersymmetric charged black holes with SU(2)_L spin in IIB string theory compactified to five dimensions on K^3 x S^1 are considered. These have a near-horizon or NHEK region with an enhanced SL(2,R)_L conformal symmetry. It is shown that the NHEK geometry has a second, inequivalent, asymptotically flat extension in which the radius of the S^1 becomes infinite but the radius of the angular circles of SU(2)_L orbits approach a constant. The asymptotic charges associated to the second solution identify it as a 5D D1-D5-Taub-NUT black string with certain nonzero worldvolume charge densities, temperatures and chemical potentials. The dual of the NHEK geometry is then identified as an IR limit of this wrapped brane configuration.Comment: 11 page

    Semimetallic behavior in Heusler-type Ru2TaAl and thermoelectric performance improved by off-stoichiometry

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    We report a study of the temperature-dependent electrical resistivity, Seebeck coefficient, thermal conductivity, specific heat, and Al27 nuclear magnetic resonance (NMR) in Heusler-type Ru2TaAl, to shed light on its semimetallic behavior. While the temperature dependence of the electrical resistivity exhibits semiconductorlike behavior, the analysis of low-temperature specific heat reveals a residual Fermi-level density of states (DOS). Both observations can be realized by means of a semimetallic scenario with the Fermi energy located in the pseudogap of the electronic DOS. The NMR Knight shift and spin-lattice relaxation rate show activated behavior at higher temperatures, attributing to the thermally excited carriers across a pseudogap in Ru2TaAl. From the first-principles band structure calculations, we further provide a clear picture that an indirect overlap between electron and hole pockets is responsible for the formation of a pseudogap in the vicinity of the Fermi level of Ru2TaAl. In addition, an effort for improving the thermoelectric performance of Ru2TaAl has been made by investigating the thermoelectric properties of Ru1.95Ta1.05Al. We found significant enhancements in the electrical conductivity and Seebeck coefficient and marked reduction in the thermal conductivity via the off-stoichiomet ric approach. This leads to an increase in the figure-of-merit ZT value from 6.1×10-4 in Ru2TaAl to 3.4×10-3 in Ru1.95Ta1.05Al at room temperature. In this respect, a further improvement of thermoelectric performance based on Ru2TaAl through other off-stoichiometric attempts is highly probable

    On the effects of friction modelling on small punch creep test responses: a numerical investigation

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    This paper shows the results of finite element (FE) analyses of Small Punch Creep Testing (SPCT) of a P91 steel at 600°C using two different approaches to model the friction between the specimen and the punch. The numerical results obtained by using the “classical” Coulomb friction model (i.e. constant friction coefficient) have been compared with those obtained by a more modern formulation, which takes into account the effects of local loading conditions, i.e. the contact pressure, between the contacting bodies (the small disc specimen and the punch) on the coefficient of friction. The aim of the work is to investigate the effects of the friction formulation used for the calculations on the numerical results representing the output of the test, i.e. the variation of the punch displacement versus time and the time to rupture. The calculations, carried out for various load levels, showed that the friction coefficient is not constant at all positions on the contacting surface between the punch and the specimen during the deformation process. The maximum value for the coefficient of friction is reached at the contact edge, which is a very important region in the specimen, because this is the position at which most of the creep deformation occurs. As expected, the displacement versus time curve (that is usually the only output obtained from experimental SPCTs) is affected by friction formulation which is used, as this directly influences the stress and strain fields in the specimen

    Comparison of the effects of pulmonary and extra-pulmonary symptoms on health-related quality of life in patients with severe asthma

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    Objectives To survey the frequency of extra-pulmonary symptoms reported by a sample of patients with severe asthma, their contribution to quality of life and relationship to treatment pathways. Methods Consenting patients (N = 100) attending a severe asthma clinic completed questionnaire measures of extra-pulmonary symptoms (the General symptom Questionnaire, GSQ), pulmonary symptoms (Asthma Control Test, ACT), quality of life (the Severe Asthma Questionnaire, SAQ) and health status (EQ-5D-5L). Results A median of 21 extra-pulmonary symptoms were reported per week. GSQ correlated -0.65 with the ACT and 0.69 with the SAQ. Linear regression showed that both the ACT and GSQ were significant predictors of SAQ mean score, p < 0.001. In patients not receiving biologics, those with high cumulative OCS exposure (≥1120mg per year) had significantly worse scores (p < 0.05) on all questionnaires except the ACT and GSQ compared to those with low cumulative OCS exposure. Discussion Extra-pulmonary symptoms were common in this sample of people with severe asthma. Extra-pulmonary and pulmonary symptoms contribute equal variance to the score of HRQoL, showing that they are equally important contributors to patients’ experience of severe asthma. Extra-pulmonary symptoms are often overlooked in clinical medicine and in measures of quality of life. Participants receiving biologic treatments had lower extra-pulmonary symptoms possibly indicating that biologics reduce systemic symptoms more effectively than other treatments

    On Charged Lifshitz Black Holes

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    We obtain exact solutions of charged asymptotically Lifshitz black holes in arbitrary (d+2) dimensions, generalizing the four dimensional solution investigated in 0908.2611[hep-th]. We find that both the conventional Hamiltonian approach and the recently proposed method for defining mass in non-relativistic backgrounds do not work for this specific example. Thus the mass of the black hole can only be determined by the first law of thermodynamics. We also obtain perturbative solutions in five-dimensional Gauss-Bonnet gravity. The ratio of shear viscosity over entropy density and the DC conductivity are calculated in the presence of Gauss-Bonnet corrections.Comment: 24 pages, no figures, to appear in JHE

    Quantitative model for inferring dynamic regulation of the tumour suppressor gene p53

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    Background: The availability of various "omics" datasets creates a prospect of performing the study of genome-wide genetic regulatory networks. However, one of the major challenges of using mathematical models to infer genetic regulation from microarray datasets is the lack of information for protein concentrations and activities. Most of the previous researches were based on an assumption that the mRNA levels of a gene are consistent with its protein activities, though it is not always the case. Therefore, a more sophisticated modelling framework together with the corresponding inference methods is needed to accurately estimate genetic regulation from "omics" datasets. Results: This work developed a novel approach, which is based on a nonlinear mathematical model, to infer genetic regulation from microarray gene expression data. By using the p53 network as a test system, we used the nonlinear model to estimate the activities of transcription factor (TF) p53 from the expression levels of its target genes, and to identify the activation/inhibition status of p53 to its target genes. The predicted top 317 putative p53 target genes were supported by DNA sequence analysis. A comparison between our prediction and the other published predictions of p53 targets suggests that most of putative p53 targets may share a common depleted or enriched sequence signal on their upstream non-coding region. Conclusions: The proposed quantitative model can not only be used to infer the regulatory relationship between TF and its down-stream genes, but also be applied to estimate the protein activities of TF from the expression levels of its target genes

    Fog paradigm for local energy management systems

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    Cloud Computing infrastructures have been extensively deployed to support energy computation within built environments. This has ranged from predicting potential energy demand for a building (or a group of buildings), undertaking heat profile/energy distribution simulations, to understanding the impact of climate and weather on building operation. Cloud computing usage in these scenarios have benefited from resource elasticity, where the number and types of resources can change based on the complexity of the simulation being considered. While there are numerous advantages of using a cloud based energy management system, there are also significant limitations. For instance, many such systems assume that the data has been pre-staged at a cloud platform prior to simulation, and do not take account of data transfer times from the building to the simulation platform. The need for supporting computation at edge resources, which can be hosted within the building itself or shared within a building complex, has become important over recent year. Additionally, network connectivity between the sensing infrastructure within a built environment and a data centre where analysis is to be carried out can be intermittent or may fail. There is therefore also a need to better understand how computation/analysis can be carried out closer to the data capture site to complement analysis that would be undertaken at the data centre. We describe how the Fog computing paradigm can be used to support some of these requirements, extending the capability of a data centre to support energy simulation within built environments

    Rapid EST isolation from chromosome 1R of rye

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    <p>Abstract</p> <p>Background</p> <p>To obtain important expressed sequence tags (ESTs) located on specific chromosomes is currently difficult. Construction of single-chromosome EST library could be an efficient strategy to isolate important ESTs located on specific chromosomes. In this research we developed a method to rapidly isolate ESTs from chromosome 1R of rye by combining the techniques of chromosome microdissection with hybrid specific amplification (HSA).</p> <p>Results</p> <p>Chromosome 1R was isolated by a glass needle and digested with proteinase K (PK). The DNA of chromosome 1R was amplified by two rounds of PCR using a degenerated oligonucleotide 6-MW sequence with a <it>Sau</it>3AI digestion site as the primer. The PCR product was digested with <it>Sau</it>3AI and linked with adaptor HSA1, then hybridized with the <it>Sau</it>3AI digested cDNA with adaptor HSA2 of rye leaves with and without salicylic acid (SA) treatment, respectively. The hybridized DNA fragments were recovered by the HSA method and cloned into pMD18-T vector. The cloned inserts were released by PCR using the partial sequences in HSA1 and HSA2 as the primers and then sequenced. Of the 94 ESTs obtained and analyzed, 6 were known sequences located on rye chromosome 1R or on homologous group 1 chromosomes of wheat; all of them were highly homologous with ESTs of wheat, barley and/or other plants in <it>Gramineae</it>, some of which were induced by abiotic or biotic stresses. Isolated in this research were 22 ESTs with unknown functions, probably representing some new genes on rye chromosome 1R.</p> <p>Conclusion</p> <p>We developed a new method to rapidly clone chromosome-specific ESTs from chromosome 1R of rye. The information reported here should be useful for cloning and investigating the new genes found on chromosome 1R.</p

    Partitioning of on-demand electron pairs

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    We demonstrate the high fidelity splitting of electron pairs emitted on demand from a dynamic quantum dot by an electronic beam splitter. The fidelity of pair splitting is inferred from the coincidence of arrival in two detector paths probed by a measurement of the partitioning noise. The emission characteristic of the on-demand electron source is tunable from electrons being partitioned equally and independently to electron pairs being split with a fidelity of 90%. For low beam splitter transmittance we further find evidence of pair bunching violating statistical expectations for independent fermions
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