1,240 research outputs found
Hepatitis B virus prevalence in two institutions for the mentally handicapped
A comparative study of the prevalence of hepatitis B virus infection in two institutions for the mentally handicapped was carried out between April and November 1989 and April and August 1991. The institutions were situated within 10 km of each other in north-eastern Johannesburg. One institution had a significantly higher prevalence of virus markers, 68% (139 of 203) compared with 23% (40 of 176), was in poorer condition and had more severely handicapped residents with more aggressive behaviour. However, the most important difference between the two institutions was that residents at the higher-prevalence institution were admitted at a considerably younger age. Younger individuals appear to be more susceptible to infection and are more likely to develop persistent infection, thus contributing to a greater pool of infection in the institution
Primary and secondary infection with human parvovirus B19 in pregnant women in South Africa
A study of human parvovirus B19 infection in 1 967 pregnant women of all races in Johannesburg revealed an overall prevalence of 24,9% for IgG antibodies and 3,3% for IgM antibodies. Of the 64 IgM-positive sera indicating active infection, 62 were resistant to urea denaturation. No differences in the prevalence of IgG antibodies between population groups were observed, but active infections, as demonstrated by IgM antibodies, were significantly more prevalent in black than in white, coloured or Asian mothers
Neural correlates of the behavioral-autonomic interaction response to potentially threatening stimuli
Subjective assessment of emotional valence is typically associated with both brain
activity and autonomic arousal. Accurately assessing emotional salience is particularly
important when perceiving threat. We sought to characterize the neural correlates of the
interaction between behavioral and autonomic responses to potentially threatening visual
and auditory stimuli. Twenty-five healthy male subjects underwent fMRI scanning whilst
skin conductance responses (SCR) were recorded. One hundred and eighty pictures,
sentences, and sounds were assessed as âharmlessâ or âthreatening.â Individualsâ
stimulus-locked, phasic SCRs and trial-by-trial behavioral assessments were entered as
regressors into a flexible factorial design to establish their separate autonomic and
behavioral neural correlates, and convolved to examine psycho-autonomic interaction
(PAI) effects. Across all stimuli, âthreatening,â compared with âharmlessâ behavioral
assessments were associated with mainly frontal and precuneus activation with specific
within-modality activations including bilateral parahippocampal gyri (pictures), bilateral
anterior cingulate cortex (ACC) and frontal pole (sentences), and right Heschlâs gyrus
and bilateral temporal gyri (sounds). Across stimulus modalities SCRs were associated
with activation of parieto-occipito-thalamic regions, an activation pattern which was largely
replicated within-modality. In contrast, PAI analyses revealed modality-specific activations
including right fusiform/parahippocampal gyrus (pictures), right insula (sentences), and
mid-cingulate gyrus (sounds). Phasic SCR activity was positively correlated with an
individualâs propensity to assess stimuli as âthreatening.â SCRs may modulate cognitive
assessments on a âharmlessâthreateningâ dimension, thereby modulating affective tone
and hence behavior
Is antenatal screening for rubella and cytomegalovirus justified?
Altogether 2 250 asymptomatic pregnant women attending an antenatal clinic were investigated for serological evidence of past exposure to rubella and cytomegalovirus (CMV) as well as for active primary infection or reinfection/ reactivation. Only 7 (0,3%) active rubella infections were diagnosed, none of them primary. Similarly, out of 132 patients with active CMV, only 5 primary infections (3,8%) were diagnosed; the vast majority 127 (96%)- had reactivation infections. No congenital rubella infections were detected, while the transplacental transmission rate for CMV was 6,4%. None of the infants followed up was clinically affected at birth or at 6 months. No racial differences in seroprevalences for CMV or rubella immunoglobulin were observed, but immunoglobulin antibody prevalence to CMV was significantly lower in the white group. From this study there appeared to be no indication for routine antenatal screening for CMV in asymptomatic mothers
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BIODESULF(TM), A Novel Biological Technology for the Removal of H2S From Sour Natural Gas
The state-of-the-art technologies for the removal of sulfur compounds from Sour Natural Gas (SNG) are not cost-effective when scaled down to approximately 2-5 MMSCFD. At the same time, the SNG Production is increasing at 3-6 TCF/Yr and -78 TCF potential reserves are also sour. Assuming only 3% treatment of this potential SNG market is for small volume processing, the potential U.S. Market is worth 0.28 billion. Therefore, the Gas Processing Industry is seeking novel, cost-effective, environmentally compatible and operator friendly technologies applicable to the small volume producers in the range of less than 1 MMSCFD to - 5 MMSCFD. A novel biological process, BIODESTJLFTM (patent pending), developed at ARCTECH removes H{sub 2}S and other sulfur contaminants that make the Natural Gas Sour. The removal is accomplished by utilizing an adapted mixed microbial culture (consortium). A variety of anaerobic microbial consortia from ARCTECH`s Microbial Culture Collection were grown and tested for removal of H{sub 2}S. One of these consortia, termed SS-11 was found to be particularly effective. Utilizing the SS-11 consortium, a process has been developed on a laboratory-scale to remove sulfur species from Sour Natural Gas at well head production pressures and temperatures. The process has been independently evaluated and found to be promising in effectively removing H{sub 2}S and other sulfur species cost effectively
Negative Kaons in Dense Baryonic Matter
Kaon polarization operator in dense baryonic matter of arbitrary isotopic
composition is calculated including s- and p-wave kaon-baryon interactions. The
regular part of the polarization operator is extracted from the realistic
kaon-nucleon interaction based on the chiral and 1/N_c expansion. Contributions
of the Lambda(1116), Sigma(1195), Sigma*(1385) resonances are taken explicitly
into account in the pole and regular terms with inclusion of mean-field
potentials. The baryon-baryon correlations are incorporated and fluctuation
contributions are estimated. Results are applied for K- in neutron star matter.
Within our model a second-order phase transition to the s-wave K- condensate
state occurs at rho_c \gsim 4 \rho_0 once the baryon-baryon correlations are
included. We show that the second-order phase transition to the p-wave
condensate state may occur at densities in
dependence on the parameter choice. We demonstrate that a first-order phase
transition to a proton-enriched (approximately isospin-symmetric) nucleon
matter with a p-wave K- condensate can occur at smaller densities, \rho\lsim 2
\rho_0. The transition is accompanied by the suppression of hyperon
concentrations.Comment: 41 pages, 24 figures, revtex4 styl
Action research in physical education: focusing beyond myself through cooperative learning
This paper reports on the pedagogical changes that I experienced as a teacher engaged in an action research project in which I designed and implemented an indirect, developmentally appropriate and childâcentred approach to my teaching. There have been repeated calls to expunge â or at least rationalise â the use of traditional, teacherâled practice in physical education. Yet despite the advocacy of many leading academics there is little evidence that such a change of approach is occurring. In my role as teacherâasâresearcher I sought to implement a new pedagogical approach, in the form of cooperative learning, and bring about a positive change in the form of enhanced pupil learning. Data collection included a reflective journal, postâteaching reflective analysis, pupil questionnaires, student interviews, document analysis, and nonâparticipant observations. The research team analysed the data using inductive analysis and constant comparison. Six themes emerged from the data: teaching and learning, reflections on cooperation, performance, time, teacher change, and social interaction. The paper argues that cooperative learning allowed me to place social and academic learning goals on an even footing, which in turn placed a focus on pupilsâ understanding and improvement of skills in athletics alongside their interpersonal development
Resonant transmission through an open quantum dot
We have measured the low-temperature transport properties of a quantum dot
formed in a one-dimensional channel. In zero magnetic field this device shows
quantized ballistic conductance plateaus with resonant tunneling peaks in each
transition region between plateaus. Studies of this structure as a function of
applied perpendicular magnetic field and source-drain bias indicate that
resonant structure deriving from tightly bound states is split by Coulomb
charging at zero magnetic field.Comment: To be published in Phys. Rev. B (1997). 8 LaTex pages with 5 figure
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