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Search Results: 1 - 10 of 456072 matches for " P. -J. Chang "
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Measurement of the Differential Branching Fraction and Forward-Backword Asymmetry for B->K(*)l+l-
J. -T. Wei,P. Chang
Physics , 2009, DOI: 10.1103/PhysRevLett.103.171801
Abstract: We study B->K(*)l+l- decays (l=e,mu) based on a data sample of 657 million BB pairs collected with the Belle detector at the KEKB e+e- collider. We report the differential branching fraction, isospin asymmetry, K* polarization, and the forward-backward asymmetry (AFB) as functions of q^2 = M_{ll}^2*c^2. The fitted AFB spectrum exceeds the Standard Model expectation by 2.7 standard deviations. The measured branching fractions are B(B->K*l+l-)=(10.7+1.1-1.0+-0.9)*10^-7 and B(B->Kl+l-)=(4.8+0.5-0.4+-0.3)*10^-7, where the first errors are statistical and the second are systematic, with the muon to electron ratios R_K*=0.83+-0.17+-0.05 and R_K=1.03+-0.19+-0.06, respectively.
A Current Review of the Diagnostic and Treatment Strategies of Hepatic Encephalopathy
Z. Poh,P. E. J. Chang
International Journal of Hepatology , 2012, DOI: 10.1155/2012/480309
Abstract: Hepatic encephalopathy (HE) is a serious and potentially fatal complication in patients with cirrhotic liver disease. It is a spectrum ranging from minimal hepatic encephalopathy (MHE) without recognizable clinical symptoms or signs, to overt HE with risk of cerebral edema and death. HE results in diminished quality of life and survival. The broad range of neuropsychiatric manifestations reflects the range of pathophysiological mechanisms and impairment in neurotransmission that are purported to cause HE including hyperammonemia, astrocyte swelling, intra-astrocytic glutamine, upregulation of 18-kDa translocator protein (TSPO) (formerly known as peripheral benzodiazepine receptor or PBTR), and manganese. There is a myriad of diagnostic tools including simple bedside clinical assessment, and more complex neuropsychological batteries and neurophysiological tests available today. Current treatment strategies are directed at reducing ammonia, with newer agents showing some early promise. This paper describes the pathophysiology of the disease and summarises current diagnostic and treatment therapies available.
A Current Review of the Diagnostic and Treatment Strategies of Hepatic Encephalopathy
Z. Poh,P. E. J. Chang
International Journal of Hepatology , 2012, DOI: 10.1155/2012/480309
Abstract: Hepatic encephalopathy (HE) is a serious and potentially fatal complication in patients with cirrhotic liver disease. It is a spectrum ranging from minimal hepatic encephalopathy (MHE) without recognizable clinical symptoms or signs, to overt HE with risk of cerebral edema and death. HE results in diminished quality of life and survival. The broad range of neuropsychiatric manifestations reflects the range of pathophysiological mechanisms and impairment in neurotransmission that are purported to cause HE including hyperammonemia, astrocyte swelling, intra-astrocytic glutamine, upregulation of 18-kDa translocator protein (TSPO) (formerly known as peripheral benzodiazepine receptor or PBTR), and manganese. There is a myriad of diagnostic tools including simple bedside clinical assessment, and more complex neuropsychological batteries and neurophysiological tests available today. Current treatment strategies are directed at reducing ammonia, with newer agents showing some early promise. This paper describes the pathophysiology of the disease and summarises current diagnostic and treatment therapies available. 1. Introduction Hepatic encephalopathy (HE) is a common complication in patients with cirrhotic liver disease. HE not only results in a diminished quality of life, but confers a poorer prognosis in patients with underlying liver cirrhosis [1]. HE is an important event in the natural history of cirrhosis and is an independent predictor of mortality in patients with acute on chronic liver failure [2, 3]. In severe cases, it can even lead to coma or death [1]. Mortality is extremely high in overt HE with cerebral edema, and temporizing measures are often inadequate [4]. 1-year mortality for patients with severe HE in intensive care unit (ICU) is 54%, with requirement for inotropic support and acute kidney injury identified as independent predictors of ICU death and 1-year mortality [5]. Episodes of overt HE result in frequent hospitalizations, and pose a formidable burden on the healthcare system [6]. Its subclinical manifestation can be found in asmany as about 50% of cirrhotic patients without overt encephalopathy [7]. Even minimal hepatic encephalopathy (MHE), the mildest form of HE, first described by Zeegen et al. in 1970 [8], without clinically overt signs of impaired cognition has been demonstrated to diminish healthcare related quality of life [9–11] and portends a poorer prognosis [12]. Whilst MHE has been reported to occur commonly in cirrhotics, its natural history has not been well described. Its main impact appears to be cognitive and drives
A Multi-Chamber System for Analyzing the Outgassing, Deposition, and Associated Optical Degradation Properties of Materials in a Vacuum
J. Singal,R. Schindler,C. Chang,P. Czodrowski,P. Kim
Physics , 2009, DOI: 10.1063/1.3301491
Abstract: We report on the Camera Materials Test Chamber, a multi-vessel apparatus which analyzes the outgassing consequences of candidate materials for use in the vacuum cryostat of a new telescope camera. The system measures the outgassing products and rates of samples of materials at different temperatures, and collects films of outgassing products to measure the effects on light transmission in six optical bands. The design of the apparatus minimizes potential measurement errors introduced by background contamination.
Generation of dark-bright soliton trains in superfluid-superfluid counterflow
C. Hamner,J. J. Chang,P. Engels,M. A. Hoefer
Physics , 2010, DOI: 10.1103/PhysRevLett.106.065302
Abstract: The dynamics of two penetrating superfluids exhibit an intriguing variety of nonlinear effects. Using two distinguishable components of a Bose-Einstein condensate, we investigate the counterflow of two superfluids in a narrow channel. We present the first experimental observation of trains of dark-bright solitons generated by the counterflow. Our observations are theoretically interpreted by three-dimensional numerical simulations for the coupled Gross-Pitaevskii (GP) equations and the analysis of a jump in the two relatively flowing components' densities. Counterflow induced modulational instability for this miscible system is identified as the central process in the dynamics.
Formation of Quantum Shock Waves by Merging and Splitting Bose-Einstein Condensates
J. J. Chang,P. Engels,M. A. Hoefer
Physics , 2008, DOI: 10.1103/PhysRevLett.101.170404
Abstract: The processes of merging and splitting dilute-gas Bose-Einstein condensates are studied in the nonadiabatic, high-density regime. Rich dynamics are found. Depending on the experimental parameters, uniform soliton trains containing more than ten solitons or the formation of a high-density bulge as well as quantum (or dispersive) shock waves are observed experimentally within merged BECs. Our numerical simulations indicate the formation of many vortex rings. In the case of splitting a BEC, the transition from sound-wave formation to dispersive shock-wave formation is studied by use of increasingly stronger splitting barriers. These experiments realize prototypical dispersive shock situations.
Dark-dark solitons and modulational instability in miscible, two-component Bose-Einstein condensates
M. A. Hoefer,J. J. Chang,C. Hamner,P. Engels
Physics , 2010, DOI: 10.1103/PhysRevA.84.041605
Abstract: We investigate the dynamics of two miscible superfluids experiencing fast counterflow in a narrow channel. The superfluids are formed by two distinguishable components of a trapped dilute-gas Bose-Einstein condensate (BEC). The onset of counterflow-induced modulational instability throughout the cloud is observed and shown to lead to the proliferation of dark-dark vector solitons. These solitons, which we observe for the first time in a BEC, do not exist in single-component systems, exhibit intriguing beating dynamics and can experience a transverse instability leading to vortex line structures. Experimental results and multi-dimensional numerical simulations are presented.
Influence of Weight Ratio of Poly(4-vinylphenol) Insulator on Electronic Properties of InGaZnO Thin-Film Transistor
C. J. Chiu,Z. W. Pei,S. P. Chang,S. J. Chang
Journal of Nanomaterials , 2012, DOI: 10.1155/2012/698123
Abstract: Spin-coated organic PVP layers were used as dielectric layers in a-IGZO TFTs. Weight ratios of 20 : 1, 10 : 1, and 5 : 1 for PVP and PMF, a cross-linking agent, were used. The a-IGZO TFTs with the PVP : PMF ratio of 20 : 1 showed a large hysteresis in the - curve and - curve, the hysteresis increases with the increase of hydroxyl groups and also deteriorated the gate leakage current. In contrast, the devices with the PVP : PMF ratio of 5 : 1 dielectric displayed only small hysteresis. According to our experimental results, preventing the possible diffusion of hydroxyl-contained species in polymeric dielectrics is a very important factor in improving the electrical properties of high-performance a-IGZO TFT devices.
Las asociaciones de pacientes y el control de la leishmaniasis en el Perú
Guthmann,J. P.; Calmet,J.; Rosales,E.; Cruz,M.; Chang,J.; Dedet,J. P.;
Revista Panamericana de Salud Pública , 1998, DOI: 10.1590/S1020-49891998000600006
Abstract: american mucocutaneous leishmaniasis is an important health problem in peru, particularly in the mountainous cuzco region, where 25% of all new cases reported in 1989 were located. cases have increased considerably since the beginning of the 1980s, when large-scale seasonal migration to endemic zones occurred, particularly in the forest area of madre de dios, following the discovery of new gold deposits there and the deterioration in the economic situation in peru. following the lack of official response from the peruvian government, hundreds of people suffering from leishmaniasis in the cuzco area formed self-help associations with the objective of obtaining the drugs needed to treat their disease. the major achievement of this spontaneous movement, which was supported by several public and private institutions, was to encourage sick people, particularly patients with mucosal lesions, to emerge from isolation. as a result, the prevalence and incidence of the disease have now considerably decreased in the region.
The Barrier Layer of the Atlantic warm pool: Formation mechanism and influence on the mean climate
K. Balaguru,P. Chang,R. Saravanan,C. J. Jang
Tellus A , 2012, DOI: 10.3402/tellusa.v64i0.18162
Abstract: Many coupled general circulation models (CGCMs) tend to overestimate the salinity in the Atlantic warm pool or the Northwestern Tropical Atlantic (NWTA) and underestimate the surface salinity in the subtropical salinity maxima region. Most of these models also suffer from a sea-surface temperature (SST) bias in the NWTA region, leading to suggestions that the upper ocean salinity stratification may need to be improved in order to improve the barrier layer (BL) simulations and thus the SST through BL-SST-intertropical convergence zone feedbacks. In the present study, we use a CGCM to perform a set of idealised numerical experiments to test and understand the sensitivity of the BL and consequently SST in the NWTA region to freshwater flux and hence the upper ocean salinity stratification. We find that the BL of the NWTA is sensitive to upper ocean salinity changes in the Amazon river discharge region and the subtropical salinity maxima region. The BL phenomenon is further manifested by the formation of winter temperature inversions in our model simulations, the maximum magnitude of inversions being about 0.2°C. The atmospheric response causes a statistically significant reduction of mean precipitation and SST in the equatorial Atlantic region and helps improve the respective biases by 10–15%. In the region of improved BL simulation, the SST change is positive and in the right direction of bias correction, albeit weak.
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