2,563 research outputs found
Focus–specific clinical profiles in human African trypanosomiasis caused by <i>Trypanosoma brucei rhodesiense</i>
<p><b>Background:</b> Diverse clinical features have been reported in human African trypanosomiasis (HAT) foci caused by <i>Trypanosoma brucei rhodesiense</i> (<i>T.b.rhodesiense</i>) giving rise to the hypothesis that HAT manifests as a chronic disease in South-East African countries and increased in virulence towards the North. Such variation in disease severity suggests there are differences in host susceptibility to trypanosome infection and/or genetic variation in trypanosome virulence. Our molecular tools allow us to study the role of host and parasite genotypes, but obtaining matched extensive clinical data from a large cohort of HAT patients has previously proved problematic.</p>
<p><b>Methods/Principal Findings:</b>
We present a retrospective cohort study providing detailed clinical profiles of 275 HAT patients recruited in two northern foci (Uganda) and one southern focus (Malawi) in East Africa. Characteristic clinical signs and symptoms of <i>T.b.rhodesiense</i> infection were recorded and the degree of neurological dysfunction determined on admission. Clinical observations were mapped by patient estimated post-infection time. We have identified common presenting symptoms in <i>T.b.rhodesiense</i> infection; however, marked differences in disease progression and severity were identified between foci. HAT was characterised as a chronic haemo-lymphatic stage infection in Malawi, and as an acute disease with marked neurological impairment in Uganda. Within Uganda, a more rapid progression to meningo-encephaltic stage of infection was observed in one focus (Soroti) where HAT was characterised by early onset neurodysfunction; however, severe neuropathology was more frequently observed in patients in a second focus (Tororo).</p>
<p><b>Conclusions/Significance:</b> We have established focus-specific HAT clinical phenotypes showing dramatic variations in disease severity and rate of stage progression both between northern and southern East African foci and between Ugandan foci. Understanding the contribution of host and parasite factors in causing such clinical diversity in <i>T.b.rhodesiense</i> HAT has much relevance for both improvement of disease management and the identification of new drug therapy.</p>
Factors Affecting Adoption of Quality Assurance in Australian Redmeat Industries
Livestock Production/Industries,
The cost of moderate and severe COPD exacerbations to the Canadian healthcare system
SummaryBackgroundThe cost of exacerbations in chronic obstructive pulmonary disease (COPD) has not been well studied. The aim of this study was to identify and quantify the (average) cost of moderate and severe exacerbations (ME and SE, respectively) from a Canadian perspective.MethodsResources used during ME and SE were identified in a year long prospective, observational study (Resource Utilization Study In COPD (RUSIC)). The units of analysis were ME and SE. Unit costs (2006126 (N=574) and 641. For SEs, the average hospital stay was 10.0 days. The overall mean costs of outpatient, ED and hospitalization services for SE were 774 (N=140) and 9557.ConclusionThe economic burden associated with MEs and especially SEs, in Canada, is considerable and likely has a substantial impact on healthcare costs. The overall burden of exacerbations has been estimated in the range of 736 million per annum
Structured illumination microscopy using micro-pixellated light-emitting diodes
Structured illumination is a flexible and economical method of obtaining optical sectioning in wide-field microscopy [1]. In this technique the illumination system is modified to project a single-spatial frequency grid pattern onto the sample [2, 3]. The pattern can only be resolved in the focal plane and by recording images for different transverse grid positions (or phases) an image of the in-focus parts of the object can be calculated. Light emitting diodes (LEDs) are becoming increasingly popular for lighting and illumination systems due to their low cost, small dimensions, low coherence, uniform illumination, high efficiency and long lifetime. These properties, together with recent developments in high brightness, ultraviolet operation and microstructured emitter design offer great potential for LEDs as light sources for microscopy. In this paper we demonstrate a novel structured illumination microscope using a blue micro-structured light emitting diode as the illumination source. The system is potentially very compact and has no-moving-parts
Magnetization-plateau state of the S=3/2 spin chain with single ion anisotropy
We reexamine the numerical study of the magnetized state of the S=3/2 spin
chain with single ion anisotropy D(> 0) for the magnetization M=M_{S}/3, where
M_{S} is the saturation magnetization. We find at this magnetization that for
D<D_{c1}=0.387 the system is critical and the magnetization plateau does not
appear. For D > D_{c1}, the parameter region is divided into two parts D_{c1} <
D < D_{c2}=0.943 and D_{c2} < D. In each region, the system is gapful and the
M=M_{S}/3 magnetization plateau appears in the magnetization process. From our
numerical calculation, the intermediate region D_{c1} < D < D_{c2} should be
characterized by a magnetized valence-bond-solid state.Comment: 6 pages, 8 figure
A Scaling Approach to Understand the Dynamics of Fat and Lean Mass in Refueling Migrant Songbirds Measured by Quantitative Magnetic Resonance
Induced four fold anisotropy and bias in compensated NiFe/FeMn double layers
A vector spin model is used to show how frustrations within a multisublattice
antiferromagnet such as FeMn can lead to four-fold magnetic anisotropies acting
on an exchange coupled ferromagnetic film. Possibilities for the existence of
exchange bias are examined and shown to exist for the case of weak chemical
disorder at the interface in an otherwise perfect structure. A sensitive
dependence on interlayer exchange is found for anisotropies acting on the
ferromagnet through the exchange coupling, and we show that a wide range of
anisotropies can appear even for a perfect crystalline structure with an
ideally flat interface.Comment: 7 pages, 7 figure
Semiparametric theory and empirical processes in causal inference
In this paper we review important aspects of semiparametric theory and
empirical processes that arise in causal inference problems. We begin with a
brief introduction to the general problem of causal inference, and go on to
discuss estimation and inference for causal effects under semiparametric
models, which allow parts of the data-generating process to be unrestricted if
they are not of particular interest (i.e., nuisance functions). These models
are very useful in causal problems because the outcome process is often complex
and difficult to model, and there may only be information available about the
treatment process (at best). Semiparametric theory gives a framework for
benchmarking efficiency and constructing estimators in such settings. In the
second part of the paper we discuss empirical process theory, which provides
powerful tools for understanding the asymptotic behavior of semiparametric
estimators that depend on flexible nonparametric estimators of nuisance
functions. These tools are crucial for incorporating machine learning and other
modern methods into causal inference analyses. We conclude by examining related
extensions and future directions for work in semiparametric causal inference
Influence of shear flow on vesicles near a wall: a numerical study
We describe the dynamics of three-dimensional fluid vesicles in steady shear
flow in the vicinity of a wall. This is analyzed numerically at low Reynolds
numbers using a boundary element method. The area-incompressible vesicle
exhibits bending elasticity. Forces due to adhesion or gravity oppose the
hydrodynamic lift force driving the vesicle away from a wall. We investigate
three cases. First, a neutrally buoyant vesicle is placed in the vicinity of a
wall which acts only as a geometrical constraint. We find that the lift
velocity is linearly proportional to shear rate and decreases with increasing
distance between the vesicle and the wall. Second, with a vesicle filled with a
denser fluid, we find a stationary hovering state. We present an estimate of
the viscous lift force which seems to agree with recent experiments of Lorz et
al. [Europhys. Lett., vol. 51, 468 (2000)]. Third, if the wall exerts an
additional adhesive force, we investigate the dynamical unbinding transition
which occurs at an adhesion strength linearly proportional to the shear rate.Comment: 17 pages (incl. 10 figures), RevTeX (figures in PostScript
Hybrid Monte Carlo with Fat Link Fermion Actions
The use of APE smearing or other blocking techniques in lattice fermion
actions can provide many advantages. There are many variants of these fat link
actions in lattice QCD currently, such as FLIC fermions. The FLIC fermion
formalism makes use of the APE blocking technique in combination with a
projection of the blocked links back into the special unitary group. This
reunitarisation is often performed using an iterative maximisation of a gauge
invariant measure. This technique is not differentiable with respect to the
gauge field and thus prevents the use of standard Hybrid Monte Carlo simulation
algorithms. The use of an alternative projection technique circumvents this
difficulty and allows the simulation of dynamical fat link fermions with
standard HMC and its variants. The necessary equations of motion for FLIC
fermions are derived, and some initial simulation results are presented. The
technique is more general however, and is straightforwardly applicable to other
smearing techniques or fat link actions
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