1,560 research outputs found
Survival of Theileria parva in its nymphal tick vector Rhipicephalus appendiculatus under laboratory and quasi natural conditions
Groups of nymphal Rhipicephalus appendiculatus Muguga, having a mean of 1 or 9 Theileria parva Muguga-infected salivary gland acini per tick, were kept under quasi-natural conditions at an altitude of 1950 m or 20°C at a relative humidity of 85% in the laboratory and their survival and infection prevalence and abundance determined over time. Theileria parva infections for both categories of ticks survived in the nymphal ticks for 50 or 26 weeks post salivary gland infection under quasi-natural or laboratory conditions respectively. There was a distinct decline in infections in the more heavily infected nymphae under both conditions of exposure, reflecting an apparent density dependence in parasite survival. Nymphal ticks having an average infection level of 1 infected salivary gland acinus per tick, survived for up to 69 or 65 weeks post-repletion under quasi-natural or the laboratory conditions respectively. Nymphae having an average infection level of 9 infected salivary gland acini per tick survived for a similar duration under each of the 2 conditions. The infection level of 9 infected salivary gland acini per tick did not seem to significantly affect the survival of the tick vector compared to those having an average of 1 infected salivary gland acinus per tick
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Design Study of a Visible/Infrared Periscope for Intense Radiation Applications using Reflective Optics
In magnetically confined fusion devices employing deuterium-tritium (D-T) operation, refractive optical components exposed to neutron and gamma radiation can be subject to degradation of the transmission characteristics, induced luminescence, and altered mechanical properties including dimensional changes. Although radiation resistant refractive optics functioned well for the Tokamak Fusion Test Reactor (TFTR) periscope system during D-T operation, this design approach is unpromising in the much more hostile radiation environment of future D-T devices such as the International Thermonumclear Experimental Reactor (ITER). Under contract to the Princeton Plasma Physics Laboratory, Ball Aerospace of Colorado carried out a periscope design study based on the use of reflective optics. In this design, beryllium reflective input optics supported by a fused silica optical bench were interfaced to a Cassegrain relay system to transfer plasma images to remotely located cameras. This system is also capable of measuring first-wall surface temperatures in the range of 300 - 2,000 degrees C even under projected heating of the reflective optics themselves to several hundred degrees Celsius. Tests of beryllium mirror samples, however, revealed that operation at temperatures above 700 degrees C leads to a loss of specular reflectivity, thus placing an upper limit on the acceptable thermal environment. The main results of this periscope study are presented in this paper
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Operation of the TFTR Pellet Charge Exchange Diagnostic in the Pulse Counting Mode during H+ RF-minority Heating
The Pellet Charge Exchange technique on TFTR has been used primarily to obtain active charge exchange measurements using a high energy (0.5 - 4.0 MeV) neutral particle analyzer (NPA) in conjunction with impurity pellet injection (Li and B) with the scintillator-photomultiplier detector system operated in the current mode. While passive measurements using pulse counting were also obtained using this instrumentation, operation in this mode was very restrictive with pulse counting rates limited to less than {approximately}10 kHz in the absence of any significant neutron and gamma induced background signal. An upgrade to a specialized pulse counting capability which was developed by the Ioffe Institute was implemented which consisted of CsI(Tl) scintillators having features designed to minimize signals induced by background neutron and gamma rays and 16-channel pulse height analysis electronics on each of the eight NPA energy channels. Passive measurements of RF-driven energetic hydrogen minority ions which served to verify operation of the pulse counting mode are reported. It is shown that in the passive mode the main donors for the neutralization of H+ ions in this energy range are C5+ ions. The measured effective H+ tail temperatures range from 0.15 MeV at an RF power of 2 MW to 0.35 MeV at 6 MW
Variations in visceral leishmaniasis burden, mortality and the pathway to care within Bihar, India
BACKGROUND: Visceral leishmaniasis (VL) has been targeted by the WHO for elimination as a public health problem (< 1 case/10,000 people/year) in the Indian sub-continent (ISC) by 2020. Bihar State in India, which accounts for the majority of cases in the ISC, remains a major target for this elimination effort. However, there is considerable spatial, temporal and sub-population variation in occurrence of the disease and the pathway to care, which is largely unexplored and a threat to achieving the target. METHODS: Data from 6081 suspected VL patients who reported being clinically diagnosed during 2012-2013 across eight districts in Bihar were analysed. Graphical comparisons and Chi-square tests were used to determine differences in the burden of identified cases by season, district, age and sex. Log-linear regression models were fitted to onset (of symptoms)-to-diagnosis and onset-to-treatment waiting times to estimate their associations with age, sex, district and various socio-economic factors (SEFs). Logistic regression models were used to identify factors associated with mortality. RESULTS: Comparisons of VL caseloads suggested an annual cycle peaking in January-March. A 17-fold variation in the burden of identified cases across districts and under-representation of young children (0-5 years) relative to age-specific populations in Bihar were observed. Women accounted for a significantly lower proportion of the reported cases than men (41 vs 59%, P < 0.0001). Age, district of residence, house wall materials, caste, treatment cost, travelling for diagnosis and the number of treatments for symptoms before diagnosis were identified as correlates of waiting times. Mortality was associated with age, district of residence, onset-to-treatment waiting time, treatment duration, cattle ownership and cost of diagnosis. CONCLUSIONS: The distribution of VL in Bihar is highly heterogeneous, and reported caseloads and associated mortality vary significantly across different districts, posing different challenges to the elimination campaign. Socio-economic factors are important correlates of these differences, suggesting that elimination will require tailoring to population and sub-population circumstances
Seroepidemiology of group A rotavirus in suburban São Paulo, Brazil
Age-specifc patterns of rotavirus infection were investigated using a randomly selected and
representative sample of sera from a suburban community of São Paulo, Brazil screened for
class-specifc antibodies to group A rotavirus. Age-serology of anti-rotavirus IgG showed
primary infection predominant in young infants with a median age of around 18 months
consistent with IgM serology suggesting highest rates of recent infection between ages 4 and 48
months. Anti-rotavirus serum IgA prevalence increased gradually with age. Paired samples
from infants, collected 1 month apart, indicated high exposure rates with seroconversion
occurring in several infants during the reported low transmission season. Between 5 and 10%
of adults had elevated IgM levels indicative of recent infection and, potentially, of an
important contribution adults may play to rotavirus transmission. Further understanding of the
dynamics of rotavirus transmission within populations, at group and serotype level, would
benefit the design and monitoring of future immunization programmes
Community views on active case finding for tuberculosis in low- and middle-income countries: a qualitative evidence synthesis
Objectives: This is a protocol for a Cochrane Review (qualitative). The objectives are as follows:. To synthesize community views on tuberculosis active case finding programmes in low- and middle-income countries. Review question In areas of the world where tuberculosis is common, what views do communities and high-risk populations hold about tuberculosis active case finding programmes?. Target audience Policy groups at global, national and local levels considering, recommending, designing, or implementing active case finding programmes. Feasibility of programmes, as assessed by health staff, will not be part of this review
Coral Reef Fisheries Literature Review and Database Research Report, Final Technical Report
First, coral reef fisheries literature references were obtained and organised into a computer database and a user manual produced. Second, a comprehensive review article summarising and interpreting the disparate literature was written and distributed along with the database. The database and accompanying review should assist research and management of coral reef fisheries in developing countries. In the original project memorandum, it was stated that initial emphasis would be placed on fin-fish fisheries. This emphasis has been maintained throughout the projec
Solid State Neutral Particle Analyzer Array on NSTX
A Solid State Neutral Particle Analyzer (SSNPA) array has been installed on the National Spherical Torus Experiment (NSTX). The array consists of four chords viewing through a common vacuum flange. The tangency radii of the viewing chords are 60, 90, 100, and 120 cm. They view across the three co-injection neutral beam lines (deuterium, 80 keV (typ.) with tangency radii 48.7, 59.2, and 69.4 cm) on NSTX and detect co-going energetic ions. A silicon photodiode used was calibrated by using a mono-energetic deuteron beam source. Deuterons with energy above 40 keV can be detected with the present setup. The degradation of the performance was also investigated. Lead shots and epoxy are used for neutron shielding to reduce handling any hazardous heavy metal. This method also enables us to make an arbitrary shape to be fit into the complex flight tube
A new regional climate model for POLAR-CORDEX : evaluation of a 30-year hindcast with COSMO-CLM2 over Antarctica
Continent-wide climate information over the Antarctic Ice Sheet (AIS) is important to obtain accurate information of present climate and reduce uncertainties of the ice sheet mass balance response and resulting global sea level rise to future climate change. In this study, the COSMO-CLM2 Regional Climate Model is applied over the AIS and adapted for the specific meteorological and climatological conditions of the region. A 30-year hindcast was performed and evaluated against observational records consisting of long-term ground-based meteorological observations, automatic weather stations, radiosoundings, satellite records, stake measurements and ice cores. Reasonable agreement regarding the surface and upper-air climate is achieved by the COSMO-CLM2 model, comparable to the performance of other state-of-the-art climate models over the AIS. Meteorological variability of the surface climate is adequately simulated, and biases in the radiation and surface mass balance are small. The presented model therefore contributes as a new member to the COordinated Regional Downscaling EXperiment project over the AIS (POLAR-CORDEX) and the CORDEX-CORE initiative
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