84 research outputs found

    Population fluctuations of Diaphorina citri (Hem.: Liviidae) on Persian lime tree, Citrus latifolia, in Baluchestan, Iran

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    The population fluctuations of the Asian citrus psyllid nymphs, Diaphorina citri Kuwayama, was studied in Persian lime orchards on the outskirts of Sarbaz, Rask and Polan towns in southeastern Iranian Baluchestan between 2007 and 2008. The species D. citri was observed feeding on its host plant throughout the year leading to overlapping generations. The highest density (126 ± 11 and 157.63 ± 68) occurred in Sarbaz in August and March. We reported the highest density for Rask and Polan in âSeptember and Marchâ and November respectively

    Biology of Diaphorina citri (Hem.: Liviidae) and parasitism by Psyllaephagus stenopsyllae (Hym.: Encyrtidae) in Baluchestan, Iran

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    پسیل آسیایی مرکبات، Diaphorina citri Kuwayama، یکی از آفات مهم و ناقل بیماری گرینینگ مرکبات می‌باشد. در این پژوهش، ویژگی‌های زیستی این آفت در شرایط آزمایشگاهی و میزان پارازیتیسم آن توسط زنبور Psyllaephagus stenopsyllae (Tachikawa) مورد بررسی قرار گرفت. طول دوره قبل از تخم‌گذاری و دوره تخم‌گذاری به‌ترتیب 51/0 ± 9 و 23/0 ± 7/15 روز بود. میانگین تعداد تخم گذاشته‌شده توسط حشره ماده 7/50 ± 25/230 عدد و میانگین طول دوره پورگی 7/18 ± 83/14 روز بود. میانگین درصد پارازیتیسم توسط P. stenopsyllae، 6 ± 7 درصد تعیین شد

    Field Oriented Control of Dual Mechanical Port Machine for Hybrid Electric Vehicle

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    A dual mechanical port machine (DMPM) is used as an electrically variable transmission (EVT) in hybrid electric vehicle (HEV). In the conventional HEV, this machine is replaced by a planetary gearbox and two electric machines and makes this structure simpler. This paper presents field oriented control (FOC) for DMPM. For HEV application, drive efficiency and wide operating speed range are important. The control strategy, which uses the maximum torque per ampere (MTPA) method at low speed and flux weakening (FW) method at high speed are proposed. The model of DMPM considering the magnetic coupling between two air gaps has been developed in MATLAB/Simulink and the proposed control strategy is applied to DMPM. The simulation results have been provided with a brief discussion at the end

    Toxicity of Three Insecticides to Lysiphlebus fabarum, a Parasitoid of the Black Bean Aphid, Aphis fabae

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    The toxicity of three insecticides to Lysiphlebus fabarum (Marshall) (Hymenoptera: Braconidae: Aphidiinae), a parasitoid of Aphis fabae Scopoli (Hemiptera: Aphididae), was investigated using IOBC/wprs protocols. Abamectin 1.8 EC, imidacloprid 350 SC, and pymetrozine 25 WP were tested under laboratory conditions at recommended field rates. Immature stages of the parasitoid were exposed to materials by briefly dipping mummified aphids into insecticide solutions/suspensions or water (controls). Abamectin, imidacloprid, and pymetrozine caused 44.8, 58.5, and 14.5% mortality of mummies, respectively. Insecticides were also applied to broad bean foliage until run-off using a hand sprayer and the contact toxicity of residues was investigated after 1, 5, 16 and 30 day periods of outdoor weathering by caging adult wasps on treated plants for 24 h. One day-old residues of abamectin, imidacloprid, and pymetrozine produced 52.5, 90.0 and 57.0% mortality, respectively, and 5 day-old residues produced 28.1, 77.0 and 18.6% mortality. Sixteen day-old residues produced 8.8, 22.4 and 13.6% mortality, whereas 30 day-old residues produced 0.0, 3.2 and 1.1% mortality, respectively. On the basis of these results, abamectin and pymetrozine were classified as short-lived compounds (Class A) and imidacloprid as a slightly persistent compound (Class B)

    Viral Kinetics Suggests a Reconciliation of the Disparate Observations of the Modulation of Claudin-1 Expression on Cells Exposed to Hepatitis C Virus

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    The tight junction protein claudin-1 (CLDN1) is necessary for hepatitis C virus (HCV) entry into target cells. Recent studies have made disparate observations of the modulation of the expression of CLDN1 on cells following infection by HCV. In one study, the mean CLDN1 expression on cells exposed to HCV declined, whereas in another study HCV infected cells showed increased CLDN1 expression compared to uninfected cells. Consequently, the role of HCV in modulating CLDN1 expression, and hence the frequency of cellular superinfection, remains unclear. Here, we present a possible reconciliation of these disparate observations. We hypothesized that viral kinetics and not necessarily HCV-induced receptor modulation underlies these disparate observations. To test this hypothesis, we constructed a mathematical model of viral kinetics in vitro that mimicked the above experiments. Model predictions provided good fits to the observed evolution of the distribution of CLDN1 expression on cells following exposure to HCV. Cells with higher CLDN1 expression were preferentially infected and outgrown by cells with lower CLDN1 expression, resulting in a decline of the mean CLDN1 expression with time. At the same time, because the susceptibility of cells to infection increased with CLDN1 expression, infected cells tended to have higher CLDN1 expression on average than uninfected cells. Our study thus presents an explanation of the disparate observations of CLDN1 expression following HCV infection and points to the importance of considering viral kinetics in future studies of receptor expression on cells exposed to HCV

    The potential utility of B cell-directed biologic therapy in autoimmune diseases

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    Increasing awareness of the importance of aberrant B cell regulation in autoimmunity has driven the clinical development of novel B cell-directed biologic therapies with the potential to treat a range of autoimmune disorders. The first of these drugs—rituximab, a chimeric monoclonal antibody against the B cell-specific surface marker CD20—was recently approved for treating rheumatoid arthritis in patients with an inadequate response to other biologic therapies. The aim of this review is to discuss the potential use of rituximab in the management of other autoimmune disorders. Results from early phase clinical trials indicate that rituximab may provide clinical benefit in systemic lupus erythematosus, Sjögren’s syndrome, vasculitis, and thrombocytopenic purpura. Numerous case reports and several small pilot studies have also been published reporting the use of rituximab in conditions such as myositis, antiphospholipid syndrome, Still’s disease, and multiple sclerosis. In general, the results from these preliminary studies encourage further testing of rituximab therapy in formalized clinical trials. Based on results published to date, it is concluded that rituximab, together with other B cell-directed therapies currently under clinical development, is likely to provide an important new treatment option for a number of these difficult-to-treat autoimmune disorders

    Human cell types important for Hepatitis C Virus replication in vivo and in vitro. Old assertions and current evidence

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    Hepatitis C Virus (HCV) is a single stranded RNA virus which produces negative strand RNA as a replicative intermediate. We analyzed 75 RT-PCR studies that tested for negative strand HCV RNA in liver and other human tissues. 85% of the studies that investigated extrahepatic replication of HCV found one or more samples positive for replicative RNA. Studies using in situ hybridization, immunofluorescence, immunohistochemistry, and quasispecies analysis also demonstrated the presence of replicating HCV in various extrahepatic human tissues, and provide evidence that HCV replicates in macrophages, B cells, T cells, and other extrahepatic tissues. We also analyzed both short term and long term in vitro systems used to culture HCV. These systems vary in their purposes and methods, but long term culturing of HCV in B cells, T cells, and other cell types has been used to analyze replication. It is therefore now possible to study HIV-HCV co-infections and HCV replication in vitro

    The risks and benefits of long-term use of hydroxyurea in sickle cell anemia: A 17.5 year follow-up.

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    A randomized, controlled clinical trial established the efficacy and safety of short-term use of hydroxyurea in adult sickle cell anemia. To examine the risks and benefits of long-term hydroxyurea usage, patients in this trial were followed for 17.5 years during which they could start or stop hydroxyurea. The purpose of this follow-up was to search for adverse outcomes and estimate mortality. For each outcome and for mortality, exact 95% confidence intervals were calculated, or tests were conducted at alpha = 0.05 level (P-value \u3c0.05 for statistical significance). Although the death rate in the overall study cohort was high (43.1%; 4.4 per 100 person-years), mortality was reduced in individuals with long-term exposure to hydroxyurea. Survival curves demonstrated a significant reduction in deaths with long-term exposure. Twenty-four percent of deaths were due to pulmonary complications; 87.1% occurred in patients who never took hydroxyurea or took it for \u3c5 years. Stroke, organ dysfunction, infection, and malignancy were similar in all groups. Our results, while no longer the product of a randomized study because of the ethical concerns of withholding an efficacious treatment, suggest that long-term use of hydroxyurea is safe and might decrease mortality
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