University of Seville

About: University of Seville is a education organization based out in Seville, Andalucía, Spain. It is known for research contribution in the topics: Population & Context (language use). The organization has 20098 authors who have published 47317 publications receiving 947007 citations. The organization is also known as: Universidad de Sevilla.

Influence of human immunodeficiency virus type 1 infection on the natural course of chronic parenterally acquired Hepatitis C

Abstract: The aim of the present study was to investigate the possible role of human immunodeficiency virus (HIV) infection in the natural course of chronic hepatitis C. Seventy-six adult patients with chronic parenterally acquired hepatitis C virus (HCV) infection examined from 1989 to 1993 were enrolled; of these 32 (42.1 %) were HIV positive and 44 (57.9 %) were HIV negative. Serum HCV RNA quantitation was carried out by polymerase chain reaction in a well-characterized group (n=20; 11 HIV positive and 9 HIV negative). Distribution of histological findings in liver biopsies from both HIV-infected and noninfected patients was similar. However, within 15 years after initial HCV infection, 8 of 32 (25 %) HIV-positive patients developed cirrhosis, in comparison with only 2 of 31 (6.5 %) patients in the HIV-negative group (p<0.05); similar incidences of cirrhosis were found in both patient groups within 5 and 10 years after HCV infection. Most of the HIV-negative cirrhotic patients (9 of 11) developed cirrhosis in a time interval longer than 15 years. Finally, HCV load was almost ten times higher (1 10-fold dilution) in the HIV-positive group, but this difference did not reach statistical significance in this small study population. These results suggest that HIV infection can alter the natural course of chronic parenterally acquired hepatitis C, causing an unusually rapid progression to cirrhosis.

Selective Harmonic Mitigation Technique for Cascaded H-Bridge Converters With Nonequal DC Link Voltages

Abstract: Multilevel converters have received increased interest recently as a result of their ability to generate high quality output waveforms with a low switching frequency. This makes them very attractive for high-power applications. A cascaded H-bridge converter (CHB) is a multilevel topology which is formed from the series connection of H-bridge cells. Optimized pulse width modulation techniques such as selective harmonic elimination or selective harmonic mitigation (SHM-PWM) are capable of preprogramming the harmonic profile of the output waveform over a range of modulation indices. Such modulation methods may, however, not perform optimally if the dc links of the CHB are not balanced. This paper presents a new SHM-PWM control strategy which is capable of meeting grid codes even under nonequal dc link voltages. The method is based on the interpolation of different sets of angles obtained for specific situations of imbalance. Both simulation and experimental results are presented to validate the proposed control method.