1,091 research outputs found
Molecular and morphological characterization of Echinococcus granulosus of human and animal origin in Iran
Iran is an important endemic focus of cystic hydatid disease (CHD) where several species of intermediate host are commonly infected with Echinococcus granulosus. Isolates of E. granulosus were collected from humans and other animals from different geographical areas of Iran and characterized using both DNA (PCR-RFLP of ITS1) and morphological criteria (metacestode rostellar hook dimensions). The sheep and camel strains/genotypes were shown to occur in Iran. The sheep strain was shown to be the most common genotype of E. granulosus affecting sheep, cattle, goats and occasionally camels. The majority of camels were infected with the camel genotype as were 3 of 33 human cases. This is the first time that cases of CHD in humans have been identified in an area where a transmission cycle for the camel genotype exists. In addition, the camel genotype was found to cause infection in both sheep and cattle. Results also demonstrated that both sheep and camel strains can be readily differentiated on the basis of hook morphology alone
Representations and -theory of Discrete Groups
Let be a discrete group of finite virtual cohomological dimension
with certain finiteness conditions of the type satisfied by arithmetic groups.
We define a representation ring for , determined on its elements of
finite order, which is of finite type. Then we determine the contribution of
this ring to the topological -theory , obtaining an exact
formula for the difference in terms of the cohomology of the centralizers of
elements of finite order in .Comment: 4 page
Conductivity of 2D many-component electron gas, partially-quantized by magnetic field
The 2D semimetal consisting of heavy holes and light electrons is studied.
The consideration is based on assumption that electrons are quantized by
magnetic field while holes remain classical. We assume also that the
interaction between components is weak and the conversion between components is
absent. The kinetic equation for holes colliding with quantized electrons is
utilized. It has been stated that the inter-component friction and
corresponding correction to the dissipative conductivity {\it do
not vanish at zero temperature} due to degeneracy of the Landau levels. This
correction arises when the Fermi level crosses the Landau level.
The limits of kinetic equation applicability were found. We also study the
situation of kinetic memory when particles repeatedly return to the points of
their meeting.Comment: 13 pages, 1 figur
Non-invasive laminar inference with MEG: comparison of methods and source inversion algorithms
Magnetoencephalography (MEG) is a direct measure of neuronal current flow; its anatomical resolution is therefore not constrained by physiology but rather by data quality and the models used to explain these data. Recent simulation work has shown that it is possible to distinguish between signals arising in the deep and superficial cortical laminae given accurate knowledge of these surfaces with respect to the MEG sensors. This previous work has focused around a single inversion scheme (multiple sparse priors) and a single global parametric fit metric (free energy). In this paper we use several different source inversion algorithms and both local and global, as well as parametric and non-parametric fit metrics in order to demonstrate the robustness of the discrimination between layers. We find that only algorithms with some sparsity constraint can successfully be used to make laminar discrimination. Importantly, local t-statistics, global cross-validation and free energy all provide robust and mutually corroborating metrics of fit. We show that discrimination accuracy is affected by patch size estimates, cortical surface features, and lead field strength, which suggests several possible future improvements to this technique. This study demonstrates the possibility of determining the laminar origin of MEG sensor activity, and thus directly testing theories of human cognition that involve laminar- and frequency-specific mechanisms. This possibility can now be achieved using recent developments in high precision MEG, most notably the use of subject-specific head-casts, which allow for significant increases in data quality and therefore anatomically precise MEG recordings
Some Relations between Twisted K-theory and E8 Gauge Theory
Recently, Diaconescu, Moore and Witten provided a nontrivial link between
K-theory and M-theory, by deriving the partition function of the Ramond-Ramond
fields of Type IIA string theory from an E8 gauge theory in eleven dimensions.
We give some relations between twisted K-theory and M-theory by adapting the
method of Diaconescu-Moore-Witten and Moore-Saulina. In particular, we
construct the twisted K-theory torus which defines the partition function, and
also discuss the problem from the E8 loop group picture, in which the
Dixmier-Douady class is the Neveu-Schwarz field. In the process of doing this,
we encounter some mathematics that is new to the physics literature. In
particular, the eta differential form, which is the generalization of the eta
invariant, arises naturally in this context. We conclude with several open
problems in mathematics and string theory.Comment: 23 pages, latex2e, corrected minor errors and typos in published
versio
The views of five participating undergraduate students of the Student Associates Scheme in England
This paper reports findings from a study which explored undergraduate perceptions of the Student Associates Scheme in England (SAS). The scheme was established by the Training and Development Agency for Schools in an attempt to increase the number of graduates entering the teaching profession, particularly in shortage subjects such as the physical sciences and mathematics. The scheme places undergraduate students on short-term placements in secondary schools throughout England to provide them with experiences that may encourage them to consider teaching as a career option. Findings show that the SAS school placements were a positive experience for the students participating in this study. However, a question emerged as to whether or not the scheme is targeting students who have yet to decide upon teaching as a career or just reinforcing the existing aspirations of students who have already decided to teach. As the scheme is attempting to increase the number of teachers entering the profession this question has important implications for this study and further work which will focus on undergraduates who think that their career ambitions would not be fulfilled by teaching
A cumulative meta-analysis of the effects of individual physical activity interventions targeting healthy adults
Despite a large and increasing evidence base on physical activity interventions, the high rates of physical inactivity and associated chronic diseases are continuing to increase globally. The purpose of this cumulative metaâanalysis was to investigate the evolution of randomized controlled trial evidence of individualâlevel physical activity interventions to asses if new trials are contributing novel evidence to the field. Through a twoâstaged search process, primary studies examining the effects of interventions targeted at increasing physical activity within healthy adult populations were pooled and selected from eligible systematic reviews. Cumulative metaâanalyses were performed on effect sizes immediately postâintervention (n = 62), and for longâterm behaviour change (â„12âmonth postâbaseline; n = 27). Sufficiency and stability of the evidence was assessed through application of preâpublished indicators. Metaâanalyses suggest overall positive intervention effects on physical activity. The evidence base for effectiveness immediately postâintervention reached levels of sufficiency and stability in 2007; and for longâterm followâup in 2011. In the time since, intervention effectiveness has not substantially changed, and further trials are unlikely to change the direction and magnitude of effect. Substantial evidence exists demonstrating that physical activity interventions can modify individual behaviour in controlled settings. Researchers are urged to shift focus towards investigating the optimization, implementation, sustainability and costâeffectiveness of interventions
Is there an association between airborne and surface microbes in the critical care environment?
BackgroundThere are few data and no accepted standards for air quality in the intensive care unit (ICU). Any relationship between airborne pathogens and hospital-acquired infection (HAI) risk in the ICU remains unknown.AimFirst, to correlate environmental contamination of air and surfaces in the ICU; second, to examine any association between environmental contamination and ICU-acquired staphylococcal infection.MethodsPatients, air, and surfaces were screened on 10 sampling days in a mechanically ventilated 10-bed ICU for a 10-month period. Near-patient hand-touch sites (N = 500) and air (N = 80) were screened for total colony count and Staphylococcus aureus. Air counts were compared with surface counts according to proposed standards for air and surface bioburden. Patients were monitored for ICU-acquired staphylococcal infection throughout.FindingsOverall, 235 of 500 (47%) surfaces failed the standard for aerobic counts (â€2.5 cfu/cm2). Half of passive air samples (20/40: 50%) failed the âindex of microbial airâ contamination (2 cfu/9 cm plate/h), and 15/40 (37.5%) active air samples failed the clean air standard
Monopoles and clusters
We define and study certain hyperkaehler manifolds which capture the
asymptotic behaviour of the SU(2)-monopole metric in regions where monopoles
break down into monopoles of lower charges. The rate at which these new metrics
approximate the monopole metric is exponential, as for the Gibbons-Manton
metric.Comment: v2.: relation to calorons mentioned; added explanation
- âŠ