3,166 research outputs found
Scalar field fluctuations in Schwarzschild-de Sitter space-time
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
An Exploratory Study of Capturing and Reusing Project Knowledge from a Stage-based Perspective
Trapping effects on inflation
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
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%Â versus 14.4%; odds ratio [OR]Â =Â 1.64), (21.1%Â versus 14.5%, ORÂ =Â 1.57) (PÂ <Â 0.01). Additionally, intake of oral hypoglycemic agents, calcium channel blockers (CCB), insulin, and diuretics were significantly higher in the periodontitis group with ORÂ =Â 2.49, 2.32, 2.08 and 1.79, respectively (PÂ <Â 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%Â versus 16.8%Â versus 8.0%), CCB (14.8%Â versus 14.4%Â versus 8.0%) and anticonvulsants (13.4%Â versus 7.7%Â 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
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.
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
The perfect fluid cosmology in the 1+d+D dimensional Kaluza-Klein spacetimes
for an arbitrary barotropic equation of state 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 we
exactly solve the Wheeler-DeWitt equation when the 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 spaces and the
compact spaces will eventually evolve into finite scale functions. For the
second case of , 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 spaces will be expanding forever while the scale function of the
contracting 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 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 .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
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
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
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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