5,199 research outputs found

    Gas Turbines - Some Metallurgical Considerations Involved in Their Manufacture

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    A machine learning approach to the Berezinskii-Kosterlitz-Thouless transition in classical and quantum models

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    The Berezinskii-Kosterlitz-Thouless transition is a very specific phase transition where all thermodynamic quantities are smooth. Therefore, it is difficult to determine the critical temperature in a precise way. In this paper we demonstrate how neural networks can be used to perform this task. In particular, we study how the accuracy of the transition identification depends on the way the neural networks are trained. We apply our approach to three different systems: (i) the classical XY model, (ii) the phase-fermion model, where classical and quantum degrees of freedom are coupled and (iii) the quantum XY model.Comment: 11 pages, 7 figure

    The impact of nighttime intensivists on medical intensive care unit infection-related indicators

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    In 2013, a before-and-after intervention study was conducted to evaluate the effect 24-hour intensivist coverage on length of stay and rates of catheter-associated urinary tract infection, central-line associated blood stream infection, and ventilator-associated events. Intensivist coverage for 24 hours did not decrease length of stay or result in a decrease in any specific infection rate.Infect. Control Hosp. Epidemiol. 2016;37(3):352–354</jats:p

    Strong-coupling expansion for the momentum distribution of the Bose Hubbard model with benchmarking against exact numerical results

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    A strong-coupling expansion for the Green's functions, self-energies and correlation functions of the Bose Hubbard model is developed. We illustrate the general formalism, which includes all possible inhomogeneous effects in the formalism, such as disorder, or a trap potential, as well as effects of thermal excitations. The expansion is then employed to calculate the momentum distribution of the bosons in the Mott phase for an infinite homogeneous periodic system at zero temperature through third-order in the hopping. By using scaling theory for the critical behavior at zero momentum and at the critical value of the hopping for the Mott insulator to superfluid transition along with a generalization of the RPA-like form for the momentum distribution, we are able to extrapolate the series to infinite order and produce very accurate quantitative results for the momentum distribution in a simple functional form for one, two, and three dimensions; the accuracy is better in higher dimensions and is on the order of a few percent relative error everywhere except close to the critical value of the hopping divided by the on-site repulsion. In addition, we find simple phenomenological expressions for the Mott phase lobes in two and three dimensions which are much more accurate than the truncated strong-coupling expansions and any other analytic approximation we are aware of. The strong-coupling expansions and scaling theory results are benchmarked against numerically exact QMC simulations in two and three dimensions and against DMRG calculations in one dimension. These analytic expressions will be useful for quick comparison of experimental results to theory and in many cases can bypass the need for expensive numerical simulations.Comment: 48 pages 14 figures RevTe

    Use of Facebook by Local Health Departments: Activity and Focus Areas

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    This presentation was given at the Keeneland Conference for Public Health Systems and Services Research

    Repulsive Fermions in Optical Lattices: Phase separation versus Coexistence of Antiferromagnetism and d-Superfluidity

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    We investigate a system of fermions on a two-dimensional optical square lattice in the strongly repulsive coupling regime. In this case, the interactions can be controlled by laser intensity as well as by Feshbach resonance. We compare the energetics of states with resonating valence bond d-wave superfluidity, antiferromagnetic long range order and a homogeneous state with coexistence of superfluidity and antiferromagnetism. We show that the energy density of a hole ehole(x)e_{hole}(x) has a minimum at doping x=xcx=x_c that signals phase separation between the antiferromagnetic and d-wave paired superfluid phases. The energy of the phase-separated ground state is however found to be very close to that of a homogeneous state with coexisting antiferromagnetic and superfluid orders. We explore the dependence of the energy on the interaction strength and on the three-site hopping terms and compare with the nearest neighbor hopping {\it t-J} model

    Are we committed to teach entrepreneurship in business school?: An empirical analysis of lecturers in India, Singapore and Malaysia

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    YesDespite large number of universities and institutions offering management degrees and interest in the field of entrepreneurship, very less is known about the perception of business lecturers regarding the subject of entrepreneurship, dominant pedagogy, their commitment to teaching and institutional support. The paper aims to discuss these issues. Considering this, the study was carried out with structured questionnaire among 232 lecturers of business management from selected management schools of these three South Asian countries, India, Singapore and Malaysia. In response to chief objective of the study, i.e. commitment of lecturers to teach entrepreneurship, it was found that almost 85 per cent of the respondents have shown that they feel fully committed to teach entrepreneurship and almost 35 per cent of the respondents feel that they will be unwilling to exchange current entrepreneurship teaching for teaching in other subjects. In the same vein, almost 50 per cent of the lecturers agree that their institution is keen to develop entrepreneurship education. However, in relation to training and staff development, it is found that almost 38 per cent of the lecturers have not received such a support. The study provides insight about the level of commitment that business lecturers depict to teach entrepreneurship and resources provided to them by their institute to engage in entrepreneurship education

    Development of Zwitterionic Hydrophilic Liquid Chromatography (ZICⓇHILIC-MS) metabolomics method for Shotgun analysis of human urine

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    Urine is a product of the body’s metabolism and the majority of the metabolic products exiting via the renal system are rendered polar in order to be water soluble. Resolution of urinary metabolites for metabolomic studies requires the development of HPLC separation techniques that match this feature of biological chemistry. ZIC –HILIC is an ideal candidate to take forward resolution of such metabolites where reverse phase is unable to give adequate separation. Metabolomic data has to be processed by Shotgun multivariate analysis to sift through thousands of analytes and their variables such as ion intensity. In the development of ZIC-HILIC separation with mass spectrometric (IT-ToF) detection, methodological variability have to be minimized so that any Shotgun data analysis does not reveal potential biomarker analytes that are artifacts or are adversely affected of the separation and detection technique. Here, we report the development of a ZIC-HILIC mass spectrometry method that is suitable for SIMCA P+ data analysis of urine. Variables such as resolution, run reproducibility and sample storage temperature were evaluated in tandem with SIMCA P+ data analysis and quality control pre-processing. The developed method couples quality control runs that pre-process and exclude analytes that are insufficiently robust for further candidate biomarker studies. This meant labile analytes that could not be reproduced in 70% of QC runs (which are pools of all samples run that day) were excluded. However, urine samples stored at 4°C for more than 9 months will contain metabolites that will alter and produce small molecule marker artifacts when compared to samples stored at -20°C. In conclusion, the developed method is a robust method of ZIC-HILIC mass spectrometry shotgun analysis suitable for urinary metabolome discovery of robust biomarkers
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