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Search Results: 1 - 10 of 352130 matches for " W. Goggins and J. Woo "
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A Geographical Study of Health Services Utilization Among the Elderly in Hong Kong: From Spatial Variations to Health Care Implications
M. Wong, P.H. Chau, W. Goggins and J. Woo
Health Services Insights , 2012,
Abstract: Introduction: Levels of utilization of health services vary socially and geographically. Differences in the rates of usage are also associated with geographical aspects of health care systems. The purpose of this study was to capture spatial variations in hospital health services utilization in the elderly population in Hong Kong, a Special Administrative Region of China. Materials and Methods: We carried out a secondary analysis of a database from the Hospital Authority (HA) which covers 98% (N = 243,245) of the total registered deaths in Hong Kong during 1999 to 2005. Deaths at age 65y and above (N = 184,671) were included in the analysis. Age-sex weighted mean utilization ratio of hospital services was calculated by dividing the age-sex weighted mean usage of a particular service for each district by that for the whole territory. The variation in utilization by the seniors was analyzed in terms of four types of services: length of stay (LOS) in HA hospitals, number of inpatient admissions, number of visits to specialist outpatient department (SOPD), and attendances at accident and emergency department (AED). Results: Deaths at age 65y and above contributed to 76% of the total registered deaths. Each district contributed 1.0% to 9.1% of the total number of deaths in Hong Kong. Spatial analysis of the age-sex weighted mean utilization ratio showed significant geographic variation in the use of hospital services: the range of difference in the LOS between the lowest and highest district was 44%, while some differences as high as 33%, 35% and 39% in utilization ratios were observed in relation to number of inpatient admissions, visits to SOPD, and attendances at AED respectively. However, the patterns of these variations were not consistent for the four types of service being analyzed. Conclusions: Geographic variation in the utilization of hospital health services across the 18 districts in Hong Kong among the elderly population during the last three years before death was demonstrated. However, the patterns of variation were different for the types of services being examined. Further studies using primary data at an individual level are needed to explain the variations. Detailed analysis examining the relationship between service provision, accessibility and health outcomes are also indicated in order to inform the planning of health service delivery.
Quantitative criteria for improving performance of buccal DNA for high-throughput genetic analysis
Woo Jessica G,Martin Lisa J,Ding Lili,Brown W
BMC Genetics , 2012, DOI: 10.1186/1471-2156-13-75
Abstract: Background DNA from buccal brush samples is being used for high-throughput analyses in a variety of applications, but the impact of sample type on genotyping success and downstream statistical analysis remains unclear. The objective of the current study was to determine laboratory predictors of genotyping failure among buccal DNA samples, and to evaluate the successfully genotyped results with respect to analytic quality control metrics. Sample and genotyping characteristics were compared between buccal and blood samples collected in the population-based Genetic and Environmental Risk Factors for Hemorrhagic Stroke (GERFHS) study (https://gerfhs.phs.wfubmc.edu/public/index.cfm). Results Seven-hundred eight (708) buccal and 142 blood DNA samples were analyzed for laboratory-based and analysis metrics. Overall genotyping failure rates were not statistically different between buccal (11.3%) and blood (7.0%, p = 0.18) samples; however, both the Contrast Quality Control (cQC) rate and the dynamic model (DM) call rates were lower among buccal DNA samples (p < 0.0001). The ratio of double-stranded to total DNA (ds/total ratio) in the buccal samples was the only laboratory characteristic predicting sample success (p < 0.0001). A threshold of at least 34% ds/total DNA provided specificity of 98.7% with a 90.5% negative predictive value for eliminating probable failures. After genotyping, median sample call rates (99.1% vs. 99.4%, p < 0.0001) and heterozygosity rates (25.6% vs. 25.7%, p = 0.006) were lower for buccal versus blood DNA samples, respectively, but absolute differences were small. Minor allele frequency differences from HapMap were smaller for buccal than blood samples, and both sample types demonstrated tight genotyping clusters, even for rare alleles. Conclusions We identified a buccal sample characteristic, a ratio of ds/total DNA <34%, which distinguished buccal DNA samples likely to fail high-throughput genotyping. Applying this threshold, the quality of final genotyping resulting from buccal samples is somewhat lower, but compares favorably to blood. Caution is warranted if cases and controls have different sample types, but buccal samples provide comparable results to blood samples in large-scale genotyping analyses.
Inhibition of Steroid Sulfatase Activity in Endometriotic Implants by STX64 (667Coumate): A Potential New Therapy
L. Fusi,A. Purohit,J. Brosens,L. W. L. Woo
The Scientific World Journal , 2008, DOI: 10.1100/tsw.2008.164
Quasi-Periodic Occultation by a Precessing Accretion Disk and Other Variabilities of SMC X-1
P. S. Wojdowski,G. W. Clark,A. M. Levine,J. W. Woo,S. N. Zhang
Physics , 1998, DOI: 10.1086/305893
Abstract: We have investigated the variability of the binary X-ray pulsar, SMC X-1, in data from several X-ray observatories. We confirm the ~60-day cyclic variation of the X-ray flux in the long-term monitoring data from the RXTE and CGRO observatories. X-ray light curves and spectra from the ROSAT, Ginga, and ASCA observatories show that the uneclipsed flux varies by as much as a factor of twenty between a high-flux state when 0.71 second pulses are present and a low-flux state when pulses are absent. In contrast, during eclipses when the X-rays consist of radiation scattered from circumsource matter, the fluxes and spectra in the high and low states are approximately the same. These observations prove that the low state of SMC X-1 is not caused by a reduction in the intrinsic luminosity of the source, or a spectral redistribution thereof, but rather by a quasi-periodic blockage of the line of sight, most likely by a precessing tilted accretion disk. In each of two observations in the midst of low states a brief increase in the X-ray flux and reappearance of 0.71 second pulses occurred near orbital phase 0.2. These brief increases result from an opening of the line of sight to the pulsar that may be caused by wobble in the precessing accretion disk. The records of spin up of the neutron star and decay of the binary orbit are extended during 1991-1996 by pulse-timing analysis of ROSAT, ASCA, and RXTE PCA data. The pulse profiles in various energy ranges from 0.1 to >21 keV are well represented as a combination of a pencil beam and a fan beam. Finally, there is a marked difference between the power spectra of random fluctuations in the high-state data from the RXTE PCA below and above 3.4 keV. Deviation from the fitted power law around 0.06 Hz may be QPO.
Spectrophotometric Dating of Elliptical Galaxies in the Ultraviolet
Y. -W. Lee,J. -H. Woo,S. Yi,J. -H. Park
Physics , 1999,
Abstract: The UV upturn phenomenon observed in elliptical galaxies is attractive for its potential value as an age indicator of old stellar systems. We present our most recent population models for the UV evolution of elliptical galaxies. We confirm that the dominant UV sources are either metal-poor or metal-rich hot horizontal-branch (HB) stars in local giant ellipticals, but we also note that the contribution from post-asymptotic-giant-branch (PAGB) stars overwhelms the UV spectrum at higher redshifts (look-back times). The model UV spectral energy distribution (SED) is therefore strongly affected by the current uncertainty of the mean mass of PAGB stars at higher redshifts. Fortunately, our models suggest that the far-UV observations at z > 0.35 could produce strong constraint on the PAGB mass, while observations at could produce strong constraint on the PAGB mass, while observations at lower redshifts (0.15 < z < 0.30) would still provide constraints on the models on the origin of the UV upturn. Future observations of ellipticals from the STIS/HST and planned GALEX space UV facility will provide crucial database required for more concrete calibration of our UV dating techniques for old stellar systems.
Selective Interface Control of Order Parameters in Complex Oxides
D. Meyers,Jian Liu,J. W. Freeland,S. Middey,M. Kareev,J. M. Zuo,Yi-De Chuang,Jong Woo Kim,P. J. Ryan,J. Chakhalian
Physics , 2015,
Abstract: In complex materials observed electronic phases and transitions between them often involves coupling between many degrees of freedom whose entanglement convolutes understanding of the instigating mechanism. Metal-insulator transitions are one such problem where coupling to the structural, orbital, charge, and magnetic order parameters frequently obscures the underlying physics. Here, we demonstrate a way to unravel this conundrum by heterostructuring a prototypical multi-ordered complex oxide NdNiO3 in ultra thin geometry, which preserves the metal-to-insulator transition and bulk-like magnetic order parameter, but entirely suppresses the symmetry lowering and charge order parameter. These findings illustrate the utility of heterointerfaces as a powerful method for removing competing order parameters to gain greater insight into the nature of the transition, here revealing that the magnetic order generates the transition independently, leading to a purely electronic Mott metal-insulator transition.
Double Fano resonances in a composite metamaterial possessing tripod plasmonic resonances
Y. U. Lee,E. Y. Choi,E. S. Kim,J. H. Woo,B. Kang,J. Kim,Byung Cheol Park,T. Y. Hong,Jae Hoon Kim,J. W. Wu
Physics , 2013,
Abstract: By embedding four-rod resonators inside double-split ring resonators superlattice, a planar composite metamaterial possessing tripod plasmonic resonances is fabricated. Double Fano resonances are observed where a common subradiant driven oscillator is coupled with two superradiant oscillators. As a classical analogue of four-level tripod atomic system, the transmission spectrum of the composite metamaterial exhibits a double Fano-based coherent effect. Transfer of absorbed power between two superradiant oscillators is controlled by manipulating two coupling strengths conjugated through the polarization angle of a normally incident electromagnetic wave.
Response to Comment (arXiv:1506.02787v1) on Selective Interface Control of Order Parameters in Complex Oxides
D. Meyers,Jian Liu,J. W. Freeland,S. Middey,M. Kareev,J. M. Zuo,Yi-De Chuang,Jong Woo Kim,P. Ryan,J. Chakhalian
Physics , 2015,
Abstract: In response to Lu et al, (arXiv:1506.02787v1), here we present a detailed writeup concerning the questions raised in their comment on our eprint (arXiv:1505.07451). The key question raised by Lu et al was if the bulk-like charge ordered state becomes indetectable with resonant scattering due to ultrathin film thickness. In this reply, we first detail the relation of our work to past work on the same compound by Staub et al to demonstrate that the presented data are indeed sufficient to support our claims of no charge order on ultra thin films of NdNiO3 (NNO) on NdGaO3 (NGO). Further, we demonstrate that if a well defined charge ordered phase exists in ultra thin films, it is indeed resolvable such as that in EuNiO3 (ENO).
Vortex Dynamics in an Annular Bose-Einstein Condensate
S. J. Woo,Young-Woo Son
Physics , 2012, DOI: 10.1103/PhysRevA.86.011604
Abstract: We theoretically show that the topology of a non-simply-connected annular atomic Bose-Einstein condensate enforces the inner surface waves to be always excited with outer surface excitations and that the inner surface modes are associated with induced vortex dipoles unlike the surface waves of a simply-connected one with vortex monopoles. Consequently, under stirring to drive an inner surface wave, a peculiar population oscillation between the inner and outer surface is generated regardless of annulus thickness. Moreover, a new vortex nucleation process by stirring is observed that can merge the inner vortex dipoles and outer vortex into a single vortex inside the annulus. The energy spectrum for a rotating annular condensate with a vortex at the center also reveals the distinct connection of the Tkachenko modes of a vortex lattice to its inner surface excitations.
Ideal Strength of Doped Graphene
S. J. Woo,Young-Woo Son
Physics , 2012, DOI: 10.1103/PhysRevB.87.075419
Abstract: While the mechanical distortions change the electronic properties of graphene significantly, the effects of electronic manipulation on its mechanical properties have not been known. Using first-principles calculation methods, we show that, when graphene expands isotropically under equibiaxial strain, both the electron and hole doping can maintain or improve its ideal strength slightly and enhance the critical breaking strain dramatically. Contrary to the isotropic expansions, the electron doping decreases the ideal strength as well as critical strain of uniaxially strained graphene while the hole doping increases the both. Distinct failure mechanisms depending on type of strains are shown to be origins of the different doping induced mechanical stabilities. Our findings may resolve a contradiction between recent experimental and theoretical results on the strength of graphene.
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