Hepatitis B infection in patients with acute liver failure in the United States

Occult hepatitis B virus (HBV) infection has been reported in 30% to 50% of patients with acute liver failure (ALF) in small case series. The aim of this study was to determine the prevalence of occult HBV infection in a large series of ALF patients in the United States and the prevalence of precore and core promoter variants in patients with ALF caused by hepatitis B. Sera from patients in the US ALF study and liver, when available, were tested using nested polymerase chain reaction (PCR) with primers in the HBV S and precore regions. PCR-positive samples were sequenced. Sera and/or liver from 139 patients (39 males, 100 females; mean age, 42 years) enrolled between January 1998 and December 1999 were studied. Twelve patients were diagnosed with hepatitis B, 1 with hepatitis B+C+D coinfection, and 22 had indeterminate etiology. HBV DNA was detected in the sera of 9 (6%) patients; all 9 had ALF caused by hepatitis B. HBV genotypes A, B, C, and D were present in 4, 3, 1, and 1 patients, respectively. Seven of these 9 patients had precore and/or core promoter variants. Liver from 19 patients were examined. HBV DNA was detected in the liver of 3 patients with ALF caused by hepatitis B, but in none of the remaining 16 patients with non-B ALF. Contrary to earlier reports, occult HBV infection was not present in this large series of ALF patients in the United States. HBV precore and/or core promoter variants were common among US patients with ALF caused by hepatitis B. (H EPATOLOGY 2001;33:972-976.)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34782/1/510330426_ftp.pd

The imitation game: a review of the use of artificial intelligence in colonoscopy, and endoscopists’ perceptions thereof

The development of deep learning systems in artificial intelligence (AI) has enabled advances in endoscopy, and AI-aided colonoscopy has recently been ushered into clinical practice as a clinical decision-support tool. This has enabled real-time AI-aided detection of polyps with a higher sensitivity than the average endoscopist, and evidence to support its use has been promising thus far. This review article provides a summary of currently published data relating to AI-aided colonoscopy, discusses current clinical applications, and introduces ongoing research directions. We also explore endoscopists’ perceptions and attitudes toward the use of this technology, and discuss factors influencing its uptake in clinical practice

Liver transplantation in patients with hepatitis B virus infection: Outcome in asian versus white patients

Previous studies have found that Asian patients transplanted for hepatitis B virus (HBV) infection had worse outcomes than white patients. The aim of this study was to compare outcomes in Asian and white patients listed for liver transplantation for HBV infection. Data of all patients with HBV infection listed for liver transplantation between January 1996 and June 1998 from 20 centers in North America were collected using a survey. Total patients enrolled were 325 (171 whites, 126 Asians, 28 other races). There was no difference in demographics, liver biochemistry, and HBV replicative status between Asians and whites at the time of listing. More Asians had hepatocellular carcinoma and fewer Asians had hepatitis C or D virus coinfection. At the time of this survey, 70 Asians (55%) and 99 whites (58%) had been transplanted. Actuarial 2-year survival posttransplantation for Asians (88%) and whites (92%) was similar. Recurrent HBV infection occurred in 8 (11%) Asians and 12 (12%) whites. Five patients with recurrent HBV infection died, 4 of whom were Asian. Actuarial 2-year survival for Asians versus whites with recurrent HBV infection was 60% versus 90% ( P = .04). In this large cohort of patients, overall survival and recurrent HBV infection posttransplantation were comparable between Asians and whites. However, Asians with recurrent HBV infection posttransplantation had significantly higher mortality.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34783/1/510340119_ftp.pd

USING TYPES : INVESTIGATING RELIGIOUS SUBJUGATION THROUGH THE COMBINED TEMPLES OF SINGAPORE

Master'sMASTER OF ARCHITECTURE (M.ARCH

Avalanche Characteristics And Response Time In Gallium Nitride/Silicon Carbide Heterojunction Avalanche Photodiodes

Monte Carlo (MC) method is used to simulate the avalanche characteristics, including mean multiplication gain, excess noise factor with random ionization path length (RIPL) technique and response time with random ionization time (RIT) technique, in GaN/4H-SiC, 4H-SiC/GaN, with and without dead space, of multiplication width 0.05, 0.10, 0.20 and 0.30 µm

Carrier Transport Properties of GAN in High Electric Field

The Monte Carlo (MC) simulation of the carrier transport mechanisms including impact ionization at high electric field in GaN is presented. Two non-parabolic conduction and valence bands were considered for the simulation of transport properties of electron and hole respectively. The carriers’ drift velocity and energy are simulated as a function of applied electric field at room temperature. The maximum velocity of electron is 2.85 × 107 cm/s at 140 kV/cm. The velocity of electron is saturated at 2 × 107 cm/s at electric field greater than 300 kV/cm. In our work, the velocity of hole is 5 × 106 cm/s at 500 kV/cm. Electron energy increases as the electric field increase and fluctuated at electric field greater than 600 kV/cm when impact ionization occurred. The impact ionization rates are obtained by using modified Keldysh equation. The hole impact ionization rate is higher than that of electron. This work also shows higher electron impact ionization coefficient than that of hole at electric field greater than 4.04 MV/cm

Avalanche characteristics in thin GaN avalanche photodiodes

A Monte Carlo model using random ionization path lengths describing the carriers quantum transport in thin gallium nitride (GaN) avalanche photodiodes (APDs) for ultraviolet detection in industry is developed. This work simulated avalanche characteristics such as impact ionization coefficients, mean multiplication gain and excess noise factor of GaN APDs at 0.05 μm, 0.1 μm, 0.2 μm and 0.3 μm multiplication widths in an electric field. The model simulates higher electron impact ionization coefficients than that of the hole for an electric field greater than 4.04 MV cm−1. Mean multiplication gain and excess noise factor are simulated based on the electric field dependent impact ionization coefficients. Our results show that electron-initiated multiplication gives higher multiplication gain and lower excess noise than hole-initiated multiplication for a multiplication width below 0.3 μm. Devices with dead space in general give a lower excess noise

Avalanche Multiplication and Time in Thin 4H-SiC Avalanche Photodiodes

A Monte Carlo model using random ionization path lengths describing the gain, excess noise, and time for different groups of carriers in thin 4H-SiC avalanche photodiodes (APDs) is developed. This work simulated the mean multiplication gain and excess noise of electrons and holes in 4H-SiC APDs at 0.05 µm, 0.1 µm, 0.2 µm and 0.3 µm multiplication widths in a high electric field and computed avalanche time at 0.1 μm and 0.2 µm in detail for both electron- and hole-initiated multiplication with dead space. The model simulates higher hole impact ionization coefficients than those of electrons for an electric field below 2 MV/cm. Our results show that hole-initiated multiplication gives higher gain and possesses lower excess noise than electron-initiated multiplication. The avalanche time of carriers increases with the width of the multiplication region. Longer avalanche time in a thin device may limit the performance of an APD as an optical signal sensing device. Our model shows the distribution of carriers with respect to time in detail, inclusive of the existence of secondary carriers due to different groups of feedback carriers and dead time. The hole-initiated multiplication shows faster avalanche time than electron-initiated multiplication due to the fast feedback electrons