547 research outputs found

    Introduction (<Special Sessions>International Symposium in Shanghai : Multilateral Comparative Study of the Historical Archives : Historical Documents, and Family, Business and Society in East Asia)

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    This paper presents the work on an alternative integration scheme for a half-bridge switch using 70 μm thin Si IGBTs and diodes addressing higher strength, higher toughness and higher thermal conductivity. The switch is totally bond wireless, since bonded wires increase self-heating and introduce further thermomechanical degradation mechanisms. Moreover, this solution is equipped with double side liquid cooling, and plug-in edge connectors both on the driver and load sides, allowing high power density, good accessibility and modularity. Preliminary experimental results show good switching behavior

    Modular assembly of a single phase inverter based on integrated functional block

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    This paper presents an original modular plug-in type assembly approach for a single phase-inverter. The main focus here is, indicatively, on the power range 1-20 kW, but the methodology can be transferred to higher power levels, too. At the core of the inverter lies a power-dense double-sided-cooled half-bridge power switch architecture with integrated cooler, which is interconnected to filter elements, gate-driver and control circuitry by means of compact flat connectors. The integration exercise targets, on the one hand, the optimization of the power switch performance and reliability, as well as the reduction of circuit parasitic elements; on the other, the production of a system compatible with maintenance and repairing, featuring minimized impact of single component failure on the system maintenance and repair cost and thus on its availability. Preliminary experimental tests demonstrate the nominal functionality of the inverter

    Occurrence of bovine hydatidosis and evaluation of its risk to humans in traditional communities of Southern Region of Ethiopia

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    Background: Cystic Echinococcosis/ Hydatid Disease, is an infection caused by the larval stage of the tapeworm Echinococcus granulosus, one of the most widespread parasitic zoonoses.Objective: To determine the occurrence, localization and fertility/sterility rates of hydatid cyst in cattle, to determine the prevalence of adult E. granulosus in dogs and asses the risk for human infection in traditional communities.Methods: Postmortem examination, hydatid cyst characterization,  questionnaire survey and dog stool sample examination were carried out.Results: Of the total 320 ruminants examined at backyard slaughtering, 151 (47.2%) were found harboring hydatid cysts. The liver and lungs were the two main infected organs, 34.4% and 52.3%, respectively. The majority of the cysts found were small, 54.3%, and medium, 37.7%. From the total number of cysts found, 70.2% were sterile, while 29.8% were fertile. A questionnaire survey revealed that local people were unaware of the life cycle of E. granulosus and the perpetuation of its life cycle by their cultural and traditional practices. Dogs have intimate contact with humansand other domestic animals, share the same house and also dogs do not have access for veterinary care. Stool samples of 62 dogs were collected and analyzed with a 30% prevalence of taenia infection confirmed to be E. granulosus.Conclusion: Because of the high prevalence of E. granulosus infection in dogs and hydatidosis in cattle as well as common practice of backyard slaughtering, the risk of human infection in traditional communities is suspected to be high and requires immediate attention to study the status of cystic ehinococcosis in the human population of the study area.[Ethiop. J. Health Dev. 2012;26(1):43-48

    Effects on the QT Interval of a Gatifloxacin-Containing Regimen versus Standard Treatment of Pulmonary Tuberculosis.

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    The effects on ventricular repolarization-recorded on the electrocardiogram (ECG) as lengthening of the QT interval-of acute tuberculosis and those of standard and alternative antituberculosis regimens are underdocumented. A correction factor (QTc) is introduced to make the QT independent of the heart rate, translating into the slope of the regression line between QT and heart rate being close to zero. ECGs were performed predosing and 1 to 5 h postdosing (month 1, month 2, and end of treatment) around drugs' peak concentration time in tuberculosis patients treated with either the standard 6-month treatment (rifampin and isoniazid for 6 months and pyrazinamide and ethambutol for 2 months; "control") or a test regimen with gatifloxacin, rifampin, and isoniazid given for 4 months (pyrazinamide for the first 2 months) as part of the OFLOTUB study, a randomized controlled trial conducted in five African countries. Drug levels were measured at steady state (month 1) in a subset of patients. We compared treatment effects on the QTc and modeled the effect of individual drugs' maximum concentrations of drug in serum (Cmax) on the Fridericia-corrected QT interval. A total of 1,686 patients were eligible for the correction factor analysis of QT at baseline (mean age, 30.7 years; 27% female). Median heart rate decreased from 96/min at baseline to 71/min at end of treatment, and body temperature decreased from 37.2 to 36.5°C. Pretreatment, the nonlinear model estimated the best correction factor at 0.4081 in between Bazett's (0.5) and Fridericia's (0.33) corrections. On treatment, Fridericia (QTcF) was the best correction factor. A total of 1,602 patients contributed to the analysis of QTcF by treatment arm. The peak QTcF value during follow-up was >480 ms for 21 patients (7 and 14 in the test and control arms, respectively) and >500 ms for 9 patients (5 and 4, respectively), corresponding to a risk difference of -0.9% (95% confidence interval [CI], -2.0% to 2.3%; P = 0.12) and 0.1% (95% CI, -0.6% to 0.9%; P = 0.75), respectively, between the test and control arms. One hundred six (6.6%) patients had a peak measurement change from baseline of >60 ms (adjusted between-arm difference, 0.8%; 95% CI, -1.4% to 3.1%; P = 0.47). No evidence was found of an association between Cmax of the antituberculosis drugs 1 month into treatment and the length of QTcF. Neither a standard 6-month nor a 4-month gatifloxacin-based regimen appears to carry a sizable risk of QT prolongation in patients with newly diagnosed pulmonary tuberculosis. This is to date the largest data set studying the effects of antituberculosis regimens on the QT, both for the standard regimen and for a fluoroquinolone-containing regimen. (This study has been registered at ClinicalTrials.gov under identifier NCT00216385.)

    Dryland restoration successes in the Sahel and Greater Horn of Africa show how to increase scale and impact

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    Drylands occupy more than 40% of the world’s land area and are home to some two billion people. This includes a disproportionate number of the world’s poorest people, who live in degraded and severely degraded landscapes. The United Nations Convention to Combat Desertification states on its website that 12 million hectares are lost annually to desertification and drought, and that more than 1.5 billion people are directly dependent on land that is being degraded, leading to US$42 billion in lost earnings each year. In Africa, three million hectares of forest are lost annually, along with an estimated 3% of GDP, through depleted soils. The result is that two-thirds of Africa’s forests, farmlands and pastures are now degraded. This means that millions of Africans have to live with malnutrition and poverty, and in the absence of options this further forces the poor to overexploit their natural resources to survive. This in turn intensifies the effects of climate change and hinders economic development, threatening ecological functions that are vital to national economies

    Analysis of host responses to Mycobacterium tuberculosis antigens in a multi-site study of subjects with different TB and HIV infection states in sub-Saharan Africa.

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    BACKGROUND: Tuberculosis (TB) remains a global health threat with 9 million new cases and 1.4 million deaths per year. In order to develop a protective vaccine, we need to define the antigens expressed by Mycobacterium tuberculosis (Mtb), which are relevant to protective immunity in high-endemic areas. METHODS: We analysed responses to 23 Mtb antigens in a total of 1247 subjects with different HIV and TB status across 5 geographically diverse sites in Africa (South Africa, The Gambia, Ethiopia, Malawi and Uganda). We used a 7-day whole blood assay followed by IFN-γ ELISA on the supernatants. Antigens included PPD, ESAT-6 and Ag85B (dominant antigens) together with novel resuscitation-promoting factors (rpf), reactivation proteins, latency (Mtb DosR regulon-encoded) antigens, starvation-induced antigens and secreted antigens. RESULTS: There was variation between sites in responses to the antigens, presumably due to underlying genetic and environmental differences. When results from all sites were combined, HIV- subjects with active TB showed significantly lower responses compared to both TST(-) and TST(+) contacts to latency antigens (Rv0569, Rv1733, Rv1735, Rv1737) and the rpf Rv0867; whilst responses to ESAT-6/CFP-10 fusion protein (EC), PPD, Rv2029, TB10.3, and TB10.4 were significantly higher in TST(+) contacts (LTBI) compared to TB and TST(-) contacts fewer differences were seen in subjects with HIV co-infection, with responses to the mitogen PHA significantly lower in subjects with active TB compared to those with LTBI and no difference with any antigen. CONCLUSIONS: Our multi-site study design for testing novel Mtb antigens revealed promising antigens for future vaccine development. The IFN-γ ELISA is a cheap and useful tool for screening potential antigenicity in subjects with different ethnic backgrounds and across a spectrum of TB and HIV infection states. Analysis of cytokines other than IFN-γ is currently on-going to determine correlates of protection, which may be useful for vaccine efficacy trials

    Effectiveness of Genomic Prediction of Maize Hybrid Performance in Different Breeding Populations and Environments

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    Genomic prediction is expected to considerably increase genetic gains by increasing selection intensity and accelerating the breeding cycle. In this study, marker effects estimated in 255 diverse maize (Zea mays L.) hybrids were used to predict grain yield, anthesis date, and anthesis-silking interval within the diversity panel and testcross progenies of 30 F(2)-derived lines from each of five populations. Although up to 25% of the genetic variance could be explained by cross validation within the diversity panel, the prediction of testcross performance of F(2)-derived lines using marker effects estimated in the diversity panel was on average zero. Hybrids in the diversity panel could be grouped into eight breeding populations differing in mean performance. When performance was predicted separately for each breeding population on the basis of marker effects estimated in the other populations, predictive ability was low (i.e., 0.12 for grain yield). These results suggest that prediction resulted mostly from differences in mean performance of the breeding populations and less from the relationship between the training and validation sets or linkage disequilibrium with causal variants underlying the predicted traits. Potential uses for genomic prediction in maize hybrid breeding are discussed emphasizing the need of (1) a clear definition of the breeding scenario in which genomic prediction should be applied (i.e., prediction among or within populations), (2) a detailed analysis of the population structure before performing cross validation, and (3) larger training sets with strong genetic relationship to the validation set

    Evaluation of cytokine responses against novel Mtb antigens as diagnostic markers for TB disease.

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    OBJECTIVE: We investigated the accuracy of host markers detected in Mtb antigen-stimulated whole blood culture supernatant in the diagnosis of TB. METHODS: Prospectively, blood from 322 individuals with presumed TB disease from six African sites was stimulated with four different Mtb antigens (Rv0081, Rv1284, ESAT-6/CFP-10, and Rv2034) in a 24 h whole blood stimulation assay (WBA). The concentrations of 42 host markers in the supernatants were measured using the Luminex multiplex platform. Diagnostic biosignatures were investigated through the use of multivariate analysis techniques. RESULTS: 17% of the participants were HIV infected, 106 had active TB disease and in 216 TB was excluded. Unstimulated concentrations of CRP, SAA, ferritin and IP-10 had better discriminating ability than markers from stimulated samples. Accuracy of marker combinations by general discriminant analysis (GDA) identified a six analyte model with 77% accuracy for TB cases and 84% for non TB cases, with a better performance in HIV uninfected patients. CONCLUSIONS: A biosignature of 6 cytokines obtained after stimulation with four Mtb antigens has moderate potential as a diagnostic tool for pulmonary TB disease individuals and stimulated marker expression had no added value to unstimulated marker performance
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