255 research outputs found

    Molecular analysis of Mycobacterium tuberculosis DNA from a family of 18th century Hungarians

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    The naturally mummified remains of a mother and two daughters found in an 18th century Hungarian crypt were analysed, using multiple molecular genetic techniques to examine the epidemiology and evolution of tuberculosis. DNA was amplified from a number of targets on the Mycobacterium tuberculosis genome, including DNA from IS6110, gyrA, katG codon 463, oxyR, dnaA–dnaN, mtp40, plcD and the direct repeat (DR) region. The strains present in the mummified remains were identified as M. tuberculosis and not Mycobacterium bovis, from katG and gyrA genotyping, PCR from the oxyR and mtp40 loci, and spoligotyping. Spoligotyping divided the samples into two strain types, and screening for a deletion in the MT1801–plcD region initially divided the strains into three types. Further investigation showed, however, that an apparent deletion was due to poor DNA preservation. By comparing the effect of PCR target size on the yield of amplicon, a clear difference was shown between 18th century and modern M. tuberculosis DNA. A two-centre system was used to confirm the findings of this study, which clearly demonstrate the value of using molecular genetic techniques to study historical cases of tuberculosis and the care required in drawing conclusions. The genotyping and spoligotyping results are consistent with the most recent theory of the evolution and spread of the modern tuberculosis epidemic

    Nonohmic conductivity as a probe of crossover from diffusion to hopping in two dimensions

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    We show that the study of conductivity nonlinearity gives a possibility to determine the condition when the diffusion conductivity changes to the hopping one with increasing disorder. It is experimentally shown that the conductivity of single quantum well GaAs/InGaAs/GaAs heterostructures behaves like diffusive one down to value of order 102e2/h10^{-2}e^2/h.Comment: 4 pages, 2 figure

    Balancing demands and resources in sport:adaptation and validation of the demand-induced strain compensation questionnaire for use in sport

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    Too high demands, combined with a lack of resources, are often detrimental to athletic health and well-being. However, a valid and reliable instrument to investigate different dimensions of demands and resources in sport is currently unavailable. Therefore, the present study examines the psychometric properties of an existing and well-validated survey instrument on demands and resources at task-level that was adapted to sport. This instrument, the Demand-Induced Strain Compensation Questionnaire for Sport (DISQ-SPORT), was empirically tested among 1,101 athletes (416 females and 685 males) from a variety of sports and in different languages. Results supported the proposed six-factor structure of the instrument, consisting of physical, cognitive, and emotional demands and resources. Internal consistencies of all subscales were satisfactory and the instrument was invariant across type of sport, competitive level and language. Continued evaluation of the psychometric properties of the DISQ-SPORT, especially in terms of content validity and test-retest stability, is nevertheless warranted. Theoretical and practical implications as well as areas for future research are discussed.</p

    Effect of intersubband scattering on weak localization in 2D systems

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    The theory of weak localization is generalized for multilevel 2D systems taking into account intersubband scattering. It is shown that weak intersubband scattering which is negligible in a classical transport, affects strongly the weak-localization correction to conductivity. The anomalous magnetoresistance is calculated in the whole range of classically low magnetic fields. This correction to conductivity is shown to depend strongly on the ratios of occupied level concentrations. It is demonstrated that at relatively low population of the excited subband, it is necessary to use the present theory because the high-field limit asimptotics is shown to be achieved only in classical magnetic fields.Comment: 18 pages, 4 figures. Accepted to Phys. Rev. B 6

    High performance checksum computation for fault-tolerant MPI over InfiniBand

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    International audienceWith the increase of the number of nodes in clusters, the probability of failures and unusual events increases. In this paper, we present checksum mechanisms to detect data corruption. We study the impact of checksums on network communication performance and we propose a mechanism to amortize their cost on InfiniBand. We have implemented our mechanisms in the NEWMADELEINE communication library. Our evaluation shows that our mechanisms to ensure message integrity do not impact noticeably the application performance, which is an improvement over the state of the art MPI implementations

    Total photoproduction cross-section at very high energy

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    In this paper we apply to photoproduction total cross-section a model we have proposed for purely hadronic processes and which is based on QCD mini-jets and soft gluon re-summation. We compare the predictions of our model with the HERA data as well as with other models. For cosmic rays, our model predicts substantially higher cross-sections at TeV energies than models based on factorization but lower than models based on mini-jets alone, without soft gluons. We discuss the origin of this difference.Comment: 13 pages, 9 figures. Accepted for publication in EPJC. Changes concern added references, clarifications of the Soft Gluon Resummation method used in the paper, and other changes requested by the Journal referee which do not change the results of the original versio

    Epidemiological situation of bovine brucellosis in the State of Bahia, Brazil

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    O trabalho consistiu em estratificar o Estado da Bahia em quatro regiões com características homogêneas (circuitos produtores) para que fossem amostradas aleatoriamente, em cada uma delas, 300 propriedades. Em cada propriedade foram escolhidas, de forma aleatória, 10 a 15 fêmeas bovinas adultas, das quais foi obtida uma amostra de sangue. No total, foram amostrados 10.816 animais, provenientes de 1.413 propriedades. O protocolo de testes utilizado foi o da triagem com o teste do antígeno acidificado tamponado (Rosa Bengala) e a confirmação dos positivos com o teste do 2-mercaptoetanol. O rebanho foi considerado positivo se pelo menos um animal reagiu às duas provas sorológicas. As prevalências de focos e a de fêmeas adultas soropositivas do Estado foram de 4,2% [3,1-5,3%] e 0,66% [0,41-0,93%], respectivamente. Para os circuitos produtores foram: circuito 1, 5,8% [3,6-8,7%] e 0,86% [0,41-1,3%]; circuito 2, 3,1% [1,5-5,6%] e 1,2% [0,25-2,1%]; circuito 3, 6,3% [4,0-9,3%] e 1,7% [0,66-2,7%]; e circuito 4, 0,60% [0,07-2,2%] e 0,07 [0,00-0,21%]. Para a análise de fatores de riscos associados à doença foi aplicado um questionário epidemiológico em cada propriedade visitada. Os fatores de risco (odds ratio, OR) associados à condição de foco foram: compra de reprodutores (OR= 2,27) e presença de áreas alagadiças (OR= 1,76). A vacinação de fêmeas de três até oito meses de idade foi um fator de proteção (OR= 0,53). ____________________________________________________________________________________________________________________ ABSTRACTA study to characterize the epidemiological situation of bovine brucellosis in the State of Bahia was carried out in 2004. The State was divided into four similar production regions, 300 herds were randomly sampled in each region, and 10 to 15 adult bovine females were sampled in each of these herds. A total of 10,816 serum samples from 1,413 herds were collected. The serum samples were screened for antibodies to Brucella spp. by the Rose-Bengal Test (RBT), and all RBT-positive sera were re-tested by the 2-mercaptoethanol test (2-ME) for confirmation. A herd was considered positive if at least one animal was positive on both RBT and 2-ME tests. The prevalence of infected herds and seropositive adult bovine females in Bahia State were: 4.2% [3.1-5.3%] and 0.66% [0.41-0.93%], respectively. In the production regions, prevalence of infected herds and animals were, respectively: region 1, 5.8% [3.6-8.7%] and 0.86% [0.41-1.3%]; region 2, 3.1% [1.5-5.6%] and 1.2% [0.25-2.1%]; region 3, 6.3% [4.0-9.3%] and 1.7% [0.66-2.7%]; and region 4, 0.60% [0.07-2.2%] and 0.07%[0.00-0.2%]. In each herd, an epidemiological questionnaire was applied. The risk factors (odds ratio, OR) associated with the presence of the infection were: purchase of breeding animals (OR = 2.27) and presence of flood areas (OR= 1.76). Vaccination of heifers from three to eight months of age was a protective factor (OR=0.53)

    Evidence for charge localization in the ferromagnetic phase of La_(1-x)Ca_(x)MnO_3 from High real-space-resolution x-ray diffraction

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    High real-space-resolution atomic pair distribution functions of La_(1-x)Ca_(x)MnO_3 (x=0.12, 0.25 and 0.33) have been measured using high-energy x-ray powder diffraction to study the size and shape of the MnO_6 octahedron as a function of temperature and doping. In the paramagnetic insulating phase we find evidence for three distinct bond-lengths (~ 1.88, 1.95 and 2.15A) which we ascribe to Mn^{4+}-O, Mn^{3+}-O short and Mn^{3+}-O long bonds respectively. In the ferromagnetic metallic (FM) phase, for x=0.33 and T=20K, we find a single Mn-O bond-length; however, as the metal-insulator transition is approached either by increasing T or decreasing x, intensity progressively appears around r=2.15 and in the region 1.8 - 1.9A suggesting the appearance of Mn^{3+}-O long bonds and short Mn^{4+}-O bonds. This is strong evidence that charge localized and delocalized phases coexist close to the metal-insulator transition in the FM phase.Comment: 8 pages, 8 postscript figures, submitted to Phys. Rev.

    Epidemiological situation of bovine brucellosis in the State of São Paulo, Brazil

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    Realizou-se um estudo para caracterizar a situação epidemiológica da brucelose bovina no Estado de São Paulo. O Estado foi estratificado em sete circuitos produtores de bovinos, e 150 rebanhos com atividade reprodutiva foram aleatoriamente selecionados em cada um deles. No total, foram amostrados 1.073 rebanhos. Foram aletoriamente coletadas amostras de soro de 10 ou 15 fêmeas bovinas com idade ³24 meses, totalizando 8.761 animais. Os soros foram submetidos a um protocolo de testes em série, tendo o teste do antígeno acidificado tamponado como método de triagem e o da fixação de complemento como confirmatório. A prevalência estimada de rebanhos com pelo menos um animal soropositivo foi de 9,7% [7,8-11,6%], enquanto a prevalência estimada de animais soropositivos foi de 3,8% [0,7-6,9%], no Estado. Em cada rebanho foi aplicado um questionário epidemiológico para avaliar o grau de associação de possíveis fatores de risco (odds ratio, OR) com a doença. Propriedades com 87 ou mais bovinos (OR= 2,25) e compra de reprodutores (OR= 1,56) foram as variáveis mais associadas à condição de foco de brucelose. ____________________________________________________________________________________________________________ ARQUIVOA study to characterize the epidemiological situation of bovine brucellosis in the State of São Paulo was carried out. The state was stratified in seven cattle production regions and 150 herds with reproductive activity were randomly selected within each one. A total of 1,073 herds were sampled. In a second stage, 10 or 15 cows older than 24 month age (in herds with <100 cows and herds ≥100 cows, respectively) were bled at random. A total of 8,761 animals were bled. Sera were tested using a serial testing procedure with the Rose Bengal test as the screening method and the Complement Fixation as the confirmatory method. The estimated prevalence of herds with at least one positive animal was 9.7% [7.8-11.6%], whereas the estimated prevalence of positive cattle was 3.8% [0.7-6.9%] in São Paulo State. An epidemiological questionnaire was applied in each farm, allowing the evaluation of the association of selected risk factors with the disease. The characteristics associated with the brucellosis infected herds were farms with more than 87 bovines (OR= 2.25) and introduction of breeding cattle (OR= 1.56)
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