121 research outputs found
A Pair Polarimeter for Linearly Polarized High Energy Photons
A high quality beam of linearly polarized photons of several GeV will become
available with the coherent bremsstrahlung technique at JLab. We have developed
a polarimeter which requires about two meters of the beam line, has an
analyzing power of 20% and an efficiency of 0.02%. The layout and first results
of a polarimeter test on the laser back-scattering photon beam at SPring-8/LEPS
are presented
The decline and conservation of bumblebees
Declines in bumblebee species in the last 60 years are well documented in Europe, where they are primarily driven by habitat loss and declines in floral abundance and diversity resulting from agricultural intensification. Impacts of habitat degradation and fragmentation are likely to be compounded by the social nature of bumblebees and their largely monogamous breeding system which renders their effective population size low. Hence populations are susceptible to stochastic extinction events and inbreeding. In North America, catastrophic declines of some bumblebee species since the 1990s are probably attributable to the accidental introduction of a non-native parasite from Europe, a result of global trade in domesticated bumblebee colonies used for pollination of greenhouse crops. Given the importance of bumblebees as pollinators of crops and wildflowers, it is vital that steps be taken to prevent further declines. Suggested measures include tight regulation of commercial bumblebee use and targeted use of agri-environment schemes to enhance floristic diversity in agricultural landscapes
Genome-Wide Analysis of Subependymomas Shows Underlying Chromosomal Copy Number Changes Involving Chromosomes 6, 7, 8 and 14 in a Proportion of Cases
Subependymomas (SE) are slow-growing brain tumors that tend to occur within the ventricles of middle-aged and elderly adults. The World Health Organization classifies these tumors within the ependymoma group. Previous limited analysis of this tumor type had not revealed significant underlying cytogenetic abnormalities
Effect of TNF-α genetic variants and CCR5Δ32 on the vulnerability to HIV-1 infection and disease progression in Caucasian Spaniards
<p>Abstract</p> <p>Background</p> <p>Tumor necrosis factor alpha (TNF-α) is thought to be involved in the various immunogenetic events that influence HIV-1 infection.</p> <p>Methods</p> <p>We aimed to determine whether carriage of the <it>TNF-α-238G>A, -308G>A </it>and <it>-863 C>A </it>gene promoter single nucleotide polymorphisms (SNP) and the <it>CCR5Δ32 </it>variant allele influence the risk of HIV-1 infection and disease progression in Caucasian Spaniards. The study group consisted of 423 individuals. Of these, 239 were uninfected (36 heavily exposed but uninfected [EU] and 203 healthy controls [HC]) and 184 were HIV-1-infected (109 typical progressors [TP] and 75 long-term nonprogressors [LTNP] of over 16 years' duration). <it>TNF-α </it>SNP and the <it>CCR5Δ32 </it>allele were assessed using PCR-RFLP and automatic sequencing analysis methods on white blood cell DNA. Genotype and allele frequencies were compared using the χ 2 test and the Fisher exact test. Haplotypes were compared by logistic regression analysis.</p> <p>Results</p> <p>The distribution of <it>TNF-α-238G>A, -308G>A </it>and <it>-863 C>A </it>genetic variants was non-significantly different in HIV-1-infected patients compared with uninfected individuals: <it>-238G>A</it>, p = 0.7 and p = 0.3; <it>-308G>A</it>, p = 0.05 and p = 0.07; <it>-863 C>A</it>, p = 0.7 and p = 0.4, for genotype and allele comparisons, respectively. Haplotype analyses, however, indicated that carriers of the haplotype H3 were significantly more common among uninfected subjects (p = 0.04). Among the infected patients, the distribution of the three <it>TNF-α </it>genetic variants assessed was non-significantly different between TP and LTNP: <it>-238G>A</it>, p = 0.35 and p = 0.7; <it>-308G>A</it>, p = 0.7 and p = 0.6: <it>-863 C>A</it>, p = 0.2 and p = 0.2, for genotype and allele comparisons, respectively. Haplotype analyses also indicated non-significant associations. Subanalyses in the LTNP subset indicated that the <it>TNF-α-238A </it>variant allele was significantly overrepresented in patients who spontaneously controlled plasma viremia compared with those who had a detectable plasma viral load (genotype comparisons, p = 0.02; allele comparisons, p = 0.03). The <it>CCR5Δ32 </it>distribution was non-significantly different in HIV-1-infected patients with respect to the uninfected population (p = 0.15 and p = 0.2 for genotype and allele comparisons, respectively) and in LTNP vs TP (p = 0.4 and p = 0.5 for genotype and allele comparisons, respectively).</p> <p>Conclusions</p> <p>In our cohort of Caucasian Spaniards, <it>TNF-α </it>genetic variants could be involved in the vulnerability to HIV-1 infection. <it>TNF-α </it>genetic variants were unrelated to disease progression in infected subjects. The <it>-238G>A </it>SNP may modulate the control of viremia in LTNP. Carriage of the <it>CCR5Δ32 </it>variant allele had no effect on the risk of infection and disease progression.</p
Detection of equine herpesvirus-4 and physiological stress patterns in young Thoroughbreds consigned to a South African auction sale
Global Perspectives on Task Shifting and Task Sharing in Neurosurgery.
BACKGROUND: Neurosurgical task shifting and task sharing (TS/S), delegating clinical care to non-neurosurgeons, is ongoing in many hospital systems in which neurosurgeons are scarce. Although TS/S can increase access to treatment, it remains highly controversial. This survey investigated perceptions of neurosurgical TS/S to elucidate whether it is a permissible temporary solution to the global workforce deficit. METHODS: The survey was distributed to a convenience sample of individuals providing neurosurgical care. A digital survey link was distributed through electronic mailing lists of continental neurosurgical societies and various collectives, conference announcements, and social media platforms (July 2018-January 2019). Data were analyzed by descriptive statistics and univariate regression of Likert Scale scores. RESULTS: Survey respondents represented 105 of 194 World Health Organization member countries (54.1%; 391 respondents, 162 from high-income countries and 229 from low- and middle-income countries [LMICs]). The most agreed on statement was that task sharing is preferred to task shifting. There was broad consensus that both task shifting and task sharing should require competency-based evaluation, standardized training endorsed by governing organizations, and maintenance of certification. When perspectives were stratified by income class, LMICs were significantly more likely to agree that task shifting is professionally disruptive to traditional training, task sharing should be a priority where human resources are scarce, and to call for additional TS/S regulation, such as certification and formal consultation with a neurosurgeon (in person or electronic/telemedicine). CONCLUSIONS: Both LMIC and high-income countries agreed that task sharing should be prioritized over task shifting and that additional recommendations and regulations could enhance care. These data invite future discussions on policy and training programs
Auditor economic incentives and going-concern opinions in a limited litigious Continental European business environment: empirical evidence from Belgium
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