3,166 research outputs found

    Scalar field fluctuations in Schwarzschild-de Sitter space-time

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    We calculate quantum fluctuations of a free scalar field in the Schwarzschild-de Sitter space-time, adopting the planar coordinates that is pertinent to the presence of a black hole in an inflationary universe. In a perturbation approach, doing expansion in powers of a small black hole event horizon compared to the de Sitter cosmological horizon, we obtain time evolution of the quantum fluctuations and then derive the scalar power spectrum.Comment: 16 pages and 4 figures, accepted by Classical and Quantum Gravit

    Trapping effects on inflation

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    We develop a Lagrangian approach based on the influence functional method so as to derive self-consistently the Langevin equation for the inflaton field in the presence of trapping points along the inflaton trajectory. The Langevin equation exhibits the backreaction and the fluctuation-dissipation relation of the trapping. The fluctuation is induced by a multiplicative colored noise that can be identified as the the particle number density fluctuations and the dissipation is a new effect that may play a role in the trapping with a strong coupling. In the weak coupling regime, we calculate the power spectrum of the noise-driven inflaton fluctuations for a single trapping point and studied its variation with the trapping location. We also consider a case with closely spaced trapping points and find that the resulting power spectrum is blue.Comment: 13 pages, 2 figure

    Association between periodontitis and systemic medication intake: A case- control study

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    BackgroundTo investigate the frequency of systemic drugs taken by elderly patients with or without periodontitis and the possible association between medication consumption and the severity of periodontitis.MethodsA total of 1221 patients, including 608 with generalized moderate to severe periodontitis (periodontitis group) and 613 age- and gender- matched individuals with healthy periodontium (healthy group) were selected. Systemic conditions, medications and periodontal status were recorded. Medication intake frequency (%) was compared using unconditional logistic regression.ResultsThe top three most common medications were angiotensin- converting enzyme (ACE) inhibitors (17.9%), antidepressants (17.8%), and lipid- lowering medications (16.5%). Both ACE inhibitors and antidepressants showed statistically higher intake frequency in the periodontitis group relative to healthy controls (21.5% versus 14.4%; odds ratio [OR] = 1.64), (21.1% versus 14.5%, OR = 1.57) (P < 0.01). Additionally, intake of oral hypoglycemic agents, calcium channel blockers (CCB), insulin, and diuretics were significantly higher in the periodontitis group with OR = 2.49, 2.32, 2.08 and 1.79, respectively (P < 0.05). Several medications demonstrated a disease severity- dependent association comparing generalized severe periodontitis with moderate periodontitis and healthy group: oral hypoglycemic agents (17.4% versus 16.8% versus 8.0%), CCB (14.8% versus 14.4% versus 8.0%) and anticonvulsants (13.4% versus 7.7% versus 6.4%) with OR of 2.43, 1.99, and 2.28 (severe periodontitis versus healthy group), respectively.ConclusionThere was a significantly higher frequency of medication intake related to cardiovascular disease and diabetes in patients with periodontitis. A disease severity- dependence with medication intake frequency was also noted. This study provides indirect evidence for the possible relationship between systemic diseases and periodontitis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163409/2/jper10532_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163409/1/jper10532.pd

    EFFECTS OF SHOES MASS ON RUNNING GAIT ANALYSIS

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    The purpose of this study was to investigate the running gait analysis between different mass of shoes. Eleven male college runners from the physical education department participated in this study. The mass of experimental shoes of this study were 175 g, 255 g, 335 g and 41 5 g. When the weight of shoes increased, the maximum vertical ground reaction force increased. and the footstrike patterns changed to mid-foot strike (MFS). The center of pressure shifted forward, and the runner changed to MFS. The strike index of the strike patterns change to MFS pattern that is self-protection mechanism. Heavy shoes increase ground reaction force, thus might increasing lower extremity injuries risk

    Cultural Discourse in Taiwan. Ed. Chin-Chuan Cheng, I-Chun Wang, and Steven Tötösy de Zepetnek.

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    The collected volume Cultural Discourse in Taiwan — edited by Chin-Chuan Cheng, I-Chun Wang, and Steven Tötösy de Zepetnek and published by National Sun Yat-sen Uiniversity Press in 2009 — is intended as an addition to scholarship in the field of Taiwan Studies. The articles in the volume are in many aspects comparative and the topics discussed are in the context of literary and culture scholarship. At the same time, the volume is interdisciplinary as the articles cover historical perspectives, analyses of texts by Taiwan authors, and cultural discourse as related to Taiwan consciousness, language, and linguistic issues. Copyright release to the authors

    Quantum Perfect-Fluid Kaluza-Klein Cosmology

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    The perfect fluid cosmology in the 1+d+D dimensional Kaluza-Klein spacetimes for an arbitrary barotropic equation of state p=nρp= n \rho is quantized by using the Schutz's variational formalism. We make efforts in the mathematics to solve the problems in two cases. For the first case of the stiff fluid n=1n=1 we exactly solve the Wheeler-DeWitt equation when the dd space is flat. After the superposition of the solutions we analyze the Bohmian trajectories of the final-stage wave-packet functions and show that the flat dd spaces and the compact DD spaces will eventually evolve into finite scale functions. For the second case of n1n \approx 1, we use the approximated wavefunction in the Wheeler-DeWitt equation to find the analytic forms of the final-stage wave-packet functions. After analyzing the Bohmian trajectories we show that the flat dd spaces will be expanding forever while the scale function of the contracting DD spaces would not become zero within finite time. Our investigations indicate that the quantum effect in the quantum perfect-fluid cosmology could prevent the extra compact DD spaces in the Kaluza-Klein theory from collapsing into a singularity or that the "crack-of-doom" singularity of the extra compact dimensions is made to occur at t=t=\infty.Comment: Latex 18 pages, add section 2 to introduce the quantization of perfect flui

    Computationally Efficient 3D Eddy Current Loss Prediction in Magnets of Interior Permanent Magnet Machines

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    This paper proposes a computationally efficient method based on imaging technique, for accurate prediction of 3- dimensional (3D) eddy current loss in the rotor magnets of interior permanent magnet (IPM) machines. 2D time-stepped finite element analysis is employed to generate the radial and the tangential 2D magnetic field information within the magnet for application of the 3D imaging technique. The method is validated with 3D time-stepped finite element analysis (FEA) for an 8 pole-18 slot IPM machine evaluating its resistance limited magnet loss with increase in axial and tangential segmentation. Magnet loss considering eddy current reaction at high frequencies is evaluated from the proposed method by employing the diffusion of the 2D magnetic field variation along the axial plane. The loss associated with all the frequencies together in the armature currents is evaluated by considering each of the harmonics separately in the proposed method employing the frozen permeability to account for magnetic saturation. The results obtained are verified with 3D FEA evaluating the magnet loss at fundamental, 10 and 20 kHz time harmonics in armature currents

    Prediction of 3D High Frequency Eddy Current Loss in Rotor Magnets of SPM Machines

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    This paper proposes a computationally efficient method, for accurate prediction of 3-dimensional (3D) high frequency eddy current loss in the rotor magnets of surface mounted permanent magnet machines employing the imaging method. 2D finite element analysis (FEA) is used to generate the information on radial and tangential 2D magnetic field variations (eddy current sources) within the magnet. The diffusion of eddy current sources along the axial plane of the magnet computed analytically is incorporated in the imaging method to establish the 3D eddy current source variations within the magnet. The modified method is validated with results from 3D time-stepped finite element analysis (FEA) for an 8-pole, 18-slot permanent magnet machine, evaluating its magnet loss considering axial and circumferential segmentation

    Using Hadoop To Implement a Semantic Method Of Assessing The Quality Of Research Medical Datasets

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    In this paper a system for storing and querying medical RDF data using Hadoop is developed. This approach enables us to create an inherently parallel framework that will scale the workload across a cluster. Unlike existing solutions, our framework uses highly optimised joining strategies to enable the completion of eight separate SPAQL queries, comprised of over eighty distinct joins, in only two Map/Reduce iterations. Results are presented comparing an optimised version of our solution against Jena TDB, demonstrating the superior performance of our system and its viability for assessing the quality of medical data
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