Single-bit adaptive channel equalization for narrowband signals

In this paper, a new design of a single-bit adaptive channel equalization is proposed using sigma delta modulation and a single-bit block Least Mean Square (LMS) algorithm. With correlated narrowband input signals, this model is capable to converge and provide equivalent equalization filter with improvement in the SNR and very low Symbol Error Rate (SER). The input, filter coefficients and output values are all in single-bit and ternary format that results in a reduction in hardware complexity compared to traditional multi-bit channel equalization. Additionally, the technique avoids the need for successive conversion from multi-bit to single bit and back at the receiver and transmitter stages

Role of N-acetylcysteine in adults with non-acetaminophen-induced acute liver failure in a center without the facility of liver transplantation.

PURPOSE: We aimed to study the role of N-acetylcysteine (NAC) in non-acetaminophen-induced acute liver failure (NAI-ALF). METHODS: A total of 47 adult patients were prospectively enrolled with NAI-ALF (group 1 or NAC group) and oral NAC was given. The primary outcome was reduction in mortality with the use of NAC in NAI-ALF. The secondary outcomes were to evaluate safety of NAC and to assess factors predicting mortality. We compared these results with records of NAI-ALF patients admitted in our hospital from 2000 to 2003 (n = 44) who were not given NAC (group 2 or historical controls). RESULTS: The two groups were comparable for the etiology of ALF, prothrombin time (PT), alanine aminotransferase, creatinine, albumin, etc. The mean age in group 1 was 27.7 ± 11.8 years and in group 2 37.5 ± 18.8 years (P = 0.004). Bilirubin was 20.63 ± 11.03 and 14.36 ± 8.90 mg/dl in groups 1 and 2, respectively (P = 0.004). There were 8 (17%) and 1 (2.3%) pregnant ALF women with acute hepatitis E virus (HEV) infection in groups 1 and 2, respectively (P = 0.031). All patients were given supportive care, including mechanical ventilation. A total of 34 (37.36%) patients survived; 22 (47%) in group 1 (NAC group) and 12 (27%) in group 2 (controls) (P = 0.05). On multivariable regression analysis, patients not given NAC (odds ratio [OR] = 10.3, 95% confidence interval [CI] = 1.6-65.7), along with age older than 40 years (OR = 10.3, 95% CI = 2.0-52.5), PT more than 50 s (OR = 15.4, 95% CI = 3.8-62.2), patients requiring mechanical ventilation (OR = 20.1, 95% CI = 3.1-130.2), and interval between jaundice and hepatic encephalopathy (OR = 5.0, 95% CI = 1.3-19.1) were independent predictors of mortality

Consensus interferon plus ribavirin for Hepatitis C genotype 3 patients previously treated with pegylated interferon plus ribavirin

Background Not enough data are available about the effectiveness of consensus interferon (CIFN) among HCV genotype 3 patients who failed to respond to pegylated interferon and ribavirin. Objectives We aimed to assess the efficacy and safety of CIFN and ribavirin in non-responders and relapsers to pegylated interferon with ribavirin therapy. Patients and Methods This open-label investigator-initiated study included 44 patients who received CIFN 15 µg /day plus ribavirin 800-1200 mg daily. In patients with an early virological response (EVR), the dose of CIFN was reduced to 15 µg thrice a week for further 36 weeks. Patients with delayed virological response continued to receive daily CIFN plus ribavirin to complete 48 weeks. The patients were considered “non-responders” if there were less than 2 log reduction in HCV RNA at 12 weeks and detectable HCV RNA at 24 weeks. Results Twenty-four patients (55%) were non-responders and 20 patients were relapsers to the previous treatment with pegylated interferon plus ribavirin (mean age 43.6 ± 9.4 years, males 25 (57%)). Nine patients were clinically cirrhotic (Child A). End of treatment virological response was achieved in 19 (43.1%) patients and sustained virological response (SVR) occurred in 12 (27.3%). Out of these 12 patients, eight were non-responders and four were relapsers to the previous treatment. Advanced fibrosis or clinical cirrhosis was associated with low SVR. Adverse events were fever, myalgia, anorexia, depression, and weight loss. Two patients received granulocyte colony stimulating factor for transient neutropenia. Seven patients were given erythropoietin to improve hemoglobin, and six were treated for mild depression. Two patients developed portosystemic encephalopathy. Conclusions More than one-quarter of treatment-experienced patients with HCV genotype 3 achieved SVR after re-treatment with consensus interferon plus ribavirin

Virological and clinical characteristics of hepatitis delta virus in South Asia

<p>Abstract</p> <p>Background & Aims</p> <p>There is a paucity of data on the impact of hepatitis D virus (HDV) in patients with hepatitis B virus (HBV) infection from South Asia. We studied the impact of HDV co-infection on virological and clinical characteristics.</p> <p>Methods</p> <p>We collected data of 480 patients with HBsAg positive and a detectable HBV DNA PCR, who presented to the Aga Khan University, Karachi and Isra University in Hyderabad, Pakistan in the last 5 years. HDV co-infection was diagnosed on the basis of anti-HDV. ALT, HBeAg, HBeAb and HBV DNA PCR quantitative levels were checked in all patients. We divided all patients into two groups based on anti-HDV, and compared their biochemical, serological & virological labs and clinical spectrum. Clinical spectrum of disease included asymptomatic carrier (AC), chronic active hepatitis (CAH), immuno-tolerant phase (IP), and compensated cirrhosis (CC).</p> <p>Results</p> <p>HDV co-infection was found in 169 (35.2%). There were 164 (34.6%) HBeAg positive and 316 (65.4%) HBeAg negative patients. Mean ALT level was 66 ± 73 IU. 233 (48.5%) had raised ALT. HBV DNA level was ≥ 10e5 in 103(21.5%) patients. Overall, among HBV/HDV co-infection, 146/169 (86.4%) had suppressed HBV DNA PCR as compared to 231/311 (74.3%) patients with HBV mono-infection; p-value = 0.002. Among HBeAg negative patients 71/128(55.5%) had raised ALT levels among HBV/HDV co-infection as compared to 71/188 (37.8%) with HBV mono-infection (p-value = 0.002); levels of HBV DNA were equal in two groups; there were 27/128 (21%) patients with CC among HBV/HDV co-infection as compared to 23 (12%) in HBV mono-infection (p-value = 0.009); there were less AC (p-value = 0.009) and more CAH (p-value = 0.009) among HBV/HDV co-infection patients. Among HBeAg positive patients, serum ALT, HBV DNA levels and the spectrum of HBV were similar in the two groups.</p> <p>Conclusions</p> <p>HBV/HDV co-infection results in the suppression of HBV DNA. A fair proportion of HBV/HDV co-infected patients with HBeAg negative have active hepatitis B infection and cirrhosis as compared to those with mono-infection.</p

Impact of safety-related dose reductions or discontinuations on sustained virologic response in HCV-infected patients: Results from the GUARD-C Cohort

BACKGROUND: Despite the introduction of direct-acting antiviral agents for chronic hepatitis C virus (HCV) infection, peginterferon alfa/ribavirin remains relevant in many resource-constrained settings. The non-randomized GUARD-C cohort investigated baseline predictors of safety-related dose reductions or discontinuations (sr-RD) and their impact on sustained virologic response (SVR) in patients receiving peginterferon alfa/ribavirin in routine practice. METHODS: A total of 3181 HCV-mono-infected treatment-naive patients were assigned to 24 or 48 weeks of peginterferon alfa/ribavirin by their physician. Patients were categorized by time-to-first sr-RD (Week 4/12). Detailed analyses of the impact of sr-RD on SVR24 (HCV RNA <50 IU/mL) were conducted in 951 Caucasian, noncirrhotic genotype (G)1 patients assigned to peginterferon alfa-2a/ribavirin for 48 weeks. The probability of SVR24 was identified by a baseline scoring system (range: 0-9 points) on which scores of 5 to 9 and <5 represent high and low probability of SVR24, respectively. RESULTS: SVR24 rates were 46.1% (754/1634), 77.1% (279/362), 68.0% (514/756), and 51.3% (203/396), respectively, in G1, 2, 3, and 4 patients. Overall, 16.9% and 21.8% patients experienced 651 sr-RD for peginterferon alfa and ribavirin, respectively. Among Caucasian noncirrhotic G1 patients: female sex, lower body mass index, pre-existing cardiovascular/pulmonary disease, and low hematological indices were prognostic factors of sr-RD; SVR24 was lower in patients with 651 vs. no sr-RD by Week 4 (37.9% vs. 54.4%; P = 0.0046) and Week 12 (41.7% vs. 55.3%; P = 0.0016); sr-RD by Week 4/12 significantly reduced SVR24 in patients with scores <5 but not 655. CONCLUSIONS: In conclusion, sr-RD to peginterferon alfa-2a/ribavirin significantly impacts on SVR24 rates in treatment-naive G1 noncirrhotic Caucasian patients. Baseline characteristics can help select patients with a high probability of SVR24 and a low probability of sr-RD with peginterferon alfa-2a/ribavirin

Single-bit and conventional FIR filter comparison in state-of-art FPGA

The performance/area characteristics of a Sigma Delta Modulated Ternary FIR filter and a conventional FIR filter are compared. The implementation of both filters has been carried out in VHDL using a hierarchical adder tree organization in both pipelined and non-pipelined modes and synthesized on a small number of representative commercial FPGA devices. At a similar spectral performance, the ternary FIR filter achieved 40% higher performance than its conventional equivalent using a 12×12 bit multiplier with much lower I/O and a slightly smaller area. This performance ratio was increased to 70% in pipelined mode. Clock speeds in excess of 200MHz at 32 OSR were achieved on a low-cost FPGA and over 400MHz on a high-performance device

Performance-area tradeoffs in the design of a short word length FIR filter

We describe the area vs. performance tradeoffs for a Sigma Delta Modulated FIR filter designed with varying quantization levels. The FIR filter has been implemented in VHDL using a hierarchical adder tree organization in both pipelined and non-pipelined modes and synthesized on a small number of representative commercial FPGA devices. The synthesis results show the tradeoffs between hardware area and performance at varying quantization levels and at oversampling ratios of 32 and 64. Using a low-cost FPGA device the SQNR of the filter may be increased by 6-dB at the cost of a increased hardware but a reduction in FMAX of only about 10%. Typically, each doubling of OSR increases SQNR by over 9dB at the cost of a doubling in hardware area

Efficient Implementation of Ternary SDM Filters using State-of-the-Art FPGA

We present the analysis of a ternary FIR filter at varying OSR (Over Sampling Ratios). The sigma delta modulated ternary filter impulse responses obtained using Matlab at varying OSRs show that each doubling of OSR results in an increase of 10dB in the stopband attenuation. BT-FIR (Balanced Ternary FIR Filters) at varying OSRs have been implemented in VHDL using an efficient adder tree organization to gather the partial products. Filters in both pipelined and non-pipelined modes were synthesized on a small number of representative commercial FPGA (Field Programmable Gate Arrays) devices. Both the filter taps and binary inputs use 2\'s complement format. The synthesis results show the tradeoffs between hardware area and performance at varying OSRs. In pipelined mode, a 6MHz video stream can easily be handled at an OSR of 64, while occupying less than 8% of a Stratix-III device