2,562 research outputs found

    Correlation between hepatitis B G1896A precore mutations and HBeAg in chronic HBV patients

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    Background: Hepatitis B virus (HBV) infection is an important health concern worldwide, with critical outcomes. Hepatitis B e antigen (HBeAg) negative chronic hepatitis B is frequently caused by a mutation (G1896A) in the hepatitis B virus (HBV) precore (PC) reading frame, which creates a stop codon, causing premature termination of the HBe protein. Objectives: This study aimed to investigate the G1896A PC mutation and its effect on HBeAg detection in chronic HBV patients. Patients and Methods: In this study, 120 chronic HBV patients neither vaccinated or who had benefited from immunoglobulin therapy, were recruited. The HBV-DNA was extracted from plasma and polymerase chain reaction (PCR) was performed. Positive PCR products were subjected to automated sequencing. The HBV serological markers hepatitis B s antigen (HBsAg), HBeAg were tested. Results: One hundred out of 120 (83.3%) patients were HBeAg negative and 100% were HBsAg positive. The comparison of nucleotide sequences with the reference sequence (Accession number: AB033559) in HBeAg negative patients showed that there was a high rate of mutations in G1896A (93.18%). Conclusions: This study indicates that the rate of G1896A mutation at the PC region among HBeAg negative patients, in the Golestan province of Iran, was similar to the average rate encountered in other parts of Iran. The PC stop codon mutation was detected in 93.18% of HBeAg negative patients. Further studies with larger sample sizes are required to elucidate the exact role of these mutations in the clinical course of chronic HBV infection. © 2015, Ahvaz Jundishapur University of Medical Sciences

    An economic analysis of time-based Demand Response programs and facts devices implementation for congestion management

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    This paper explores the utilization of combination of Alternating Current Transmission System (FACTS) devices, time-based Demand Response (DR) programs, and Generation Redispatch (GR) in short-term congestion management as well as minimization of generation costs in power systems. To achieve this, a multi-stage market clearing procedure is formulated. At the first stage, the market is cleared based on generation cost minimization, without considering network constraints. Market clearing formulation for the second stage is developed considering congestion, in which FACTS device (Thyristor Controlled Series Capacitor (TCSC)), and time-based DR programs (Time of Use (TOU)) are optimally coordinated with GR in the presence of network constraints, to manage congestion at minimum costs. In addition, to make conditions more realistic, operational conditions spanning for a day (24 hours) are considered in this study. Then capabilities of these approaches in different scenarios for congestion management as well as minimization of generation costs are examined on IEEE 14-bus system. Results show that although, applications of time-based DR programs are more effective as compared to other approaches in terms of generation cost reduction but they have limited capability for congestion management due to consumption of responsive loads which usually decreases in one period and increases in another

    A theory of non-local linear drift wave transport

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    Transport events in turbulent tokamak plasmas often exhibit non-local or non-diffusive action at a distance features that so far have eluded a conclusive theoretical description. In this paper a theory of non-local transport is investigated through a Fokker-Planck equation with fractional velocity derivatives. A dispersion relation for density gradient driven linear drift modes is derived including the effects of the fractional velocity derivative in the Fokker-Planck equation. It is found that a small deviation (a few percent) from the Maxwellian distribution function alters the dispersion relation such that the growth rates are substantially increased and thereby may cause enhanced levels of transport.Comment: 22 pages, 2 figures. Manuscript submitted to Physics of Plasma

    Entanglement of Dirac fields in an expanding spacetime

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    We study the entanglement generated between Dirac modes in a 2-dimensional conformally flat Robertson-Walker universe. We find radical qualitative differences between the bosonic and fermionic entanglement generated by the expansion. The particular way in which fermionic fields get entangled encodes more information about the underlying space-time than the bosonic case, thereby allowing us to reconstruct the parameters of the history of the expansion. This highlights the importance of bosonic/fermionic statistics to account for relativistic effects on the entanglement of quantum fields.Comment: revtex4, 7 figures, I.F. previously published as Fuentes-Guridi and Fuentes-Schuller. Journal reference update

    A Fractional Fokker-Planck Model for Anomalous Diffusion

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    In this paper we present a study of anomalous diffusion using a Fokker-Planck description with fractional velocity derivatives. The distribution functions are found using numerical means for varying degree of fractionality observing the transition from a Gaussian distribution to a L\'evy distribution. The statistical properties of the distribution functions are assessed by a generalized expectation measure and entropy in terms of Tsallis statistical mechanics. We find that the ratio of the generalized entropy and expectation is increasing with decreasing fractionality towards the well known so-called sub-diffusive domain, indicating a self-organising behavior.Comment: 22 pages, 14 figure

    Seroepidemiology of rubella, measles, HBV, HCV and B19 virus within women in child bearing ages (Saravan City of Sistan and Bloochastan Province)

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    Present survey basically focused on women between 15-45 years of age resident in a town of Sistan and Baluchistan province named as Saravan city located in border of Pakistan-Iran in order to find out the seropositivity against the viruses in child bearing ages in the above stated under study community. This descriptive cross-sectional study was carried-out from 2001 up to 2002. Saravan town was divided into 4 geographical areas and each area was further sub-divided into 10 blocks and in each block 10 families were chosen randomly. In the next step by referring to each family from the chosen married women with specified age i.e., 15-45 years, 5 mL blood was collected. Serum was then separated and stored at -20°C before the assay. ELISA kit was employed to detect anti B19, anti rubella, anti measles, anti HBV and anti HCV antibody. Furthermore during samples collection a questionnaire filled for each woman under study. This study showed that 89.6% of women understudy were seropositive against measles, rubella (96.2%), B19 (59.2%), HCV (0.8%) and HBV (19.8%), respectively. According to the results of no serious problem with rubella in this area; But, about measles, the present immunity against measles in this area is insufficient. It seems that incidence of B19 infection in this region is same as other places in Iran. The rate of seropositivity against HBV and HCV indicated of these viruses circulating in the population in this area. © 2007 Academic Journals

    Concurrent infections of hepatitis C and HIV in hepatitis B patients in the north-east of Iran

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    Co-infection of HBV, HCV and HIV is common because of shared routes of viral transmission with increased risk of morbidity and mortality. Anti-HCV and HIV antibodies of168 HBV patients were assayed. Co-infection of HCV in HBV patients was seen in four cases (2.4%). Simultaneous infection of HIV in HBV patents was seen in three cases (1.8%).There was no simultaneous co-infection of HCV, HIV and HBV. It is recommended that all patients are screened for possible co-infections before initiating treatment

    Matrix-induced linear Stark effect of single dibenzoterrylene molecules in 2,3-dibromonaphthalene crystal

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    Absorption and fluorescence from single molecules can be tuned by applying an external electric field – a phenomenon known as the Stark effect. A linear Stark effect is associated to a lack of centrosymmetry of the guest in the host matrix. Centrosymmetric guests can display a linear Stark effect in disordered matrices, but the response of individual guest molecules is often relatively weak and non‐uniform, with a broad distribution of the Stark coefficients. Here we introduce a novel single‐molecule host‐guest system, dibenzoterrylene (DBT) in 2,3‐dibromonaphthalene (DBN) crystal. Fluorescent DBT molecules show excellent spectral stability with a large linear Stark effect, of the order of 1.5 GHz/kVcm−1, corresponding to an electric dipole moment change of around 2 D. Remarkably, when the electric field is aligned with the a crystal axis, nearly all DBT molecules show either positive or negative Stark shifts with similar absolute values. These results are consistent with quantum chemistry calculations. Those indicate that DBT substitutes three DBN molecules along the a‐axis, giving rise to eight equivalent embedding sites, related by the three glide planes of the orthorhombic crystal. The static dipole moment of DBT molecules is created by host‐induced breaking of the inversion symmetry. This new host–guest system is promising for applications that require a high sensitivity of fluorescent emitters to electric fields, for example to probe weak electric fields

    Profiteers of environmental change in the Swiss Alps: increase of thermophilous and generalist plants in wetland ecosystems within the last 10years

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    It has been predicted that Europe will experience a rise in temperature of 2.2-5.3°C within this century. This increase in temperature may lead to vegetation change along altitudinal gradients. To test whether vegetation composition has already changed in the recent decade due to current warming (and other concomitant environmental changes), we recorded plant species composition in 1995 and 2005/2006 in Swiss pre-alpine fen meadows (800-1,400ma.s.l.). Despite no obvious changes in the management of these fens, overall, plant species richness (cumulative number of plant species at five plots per site) significantly increased over this period. This was mainly due to an increase in the number of thermophilous, rich-soil-indicator and shade-indicator species, which corresponded to increased community productivity and shading within the vegetation layer. In contrast, fen specialists significantly declined in species numbers. The strongest species shifts occurred at the lowest sites, which overall had a higher colonization rate by new species than did sites at higher altitudes. Vegetation change along the altitudinal gradient was also affected by different types of land management: early-flowering species and species with low habitat specificity had high colonization rates in grazed fens, especially at low altitude
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