6,455 research outputs found
Modelling environmental factors correlated with podoconiosis: a geospatial study of non-filarial elephantiasis
Introduction
The precise trigger of podoconiosis — endemic non-filarial elephantiasis of the lower legs — is unknown. Epidemiological and ecological studies have linked the disease with barefoot exposure to red clay soils of volcanic origin. Histopathology investigations have demonstrated that silicon, aluminium, magnesium and iron are present in the lower limb lymph node macrophages of both patients and non-patients living barefoot on these clays. We studied the spatial variation (variations across an area) in podoconiosis prevalence and the associated environmental factors with a goal to better understanding the pathogenesis of podoconiosis.
Methods
Fieldwork was conducted from June 2011 to February 2013 in 12 kebeles (administrative units) in northern Ethiopia. Geo-located prevalence data and soil samples were collected and analysed along with secondary geological, topographic, meteorological and elevation data. Soil data were analysed for chemical composition, mineralogy and particle size, and were interpolated to provide spatially continuous information. Exploratory, spatial, univariate and multivariate regression analyses of podoconiosis prevalence were conducted in relation to primary (soil) and secondary (elevation, precipitation, and geology) covariates.
Results
Podoconiosis distribution showed spatial correlation with variation in elevation and precipitation. Exploratory analysis identified that phyllosilicate minerals, particularly clay (smectite and kaolinite) and mica groups, quartz (crystalline silica), iron oxide, and zirconium were associated with podoconiosis prevalence. The final multivariate model showed that the quantities of smectite (RR = 2.76, 95% CI: 1.35, 5.73; p = 0.007), quartz (RR = 1.16, 95% CI: 1.06, 1.26; p = 0.001) and mica (RR = 1.09, 95% CI: 1.05, 1.13; p < 0.001) in the soil had positive associations with podoconiosis prevalence.
Conclusions
More quantities of smectite, mica and quartz within the soil were associated with podoconiosis prevalence. Together with previous work indicating that these minerals may influence water absorption, potentiate infection and be toxic to human cells, the present findings suggest that these particles may play a role in the pathogenesis of podoconiosis and acute adenolymphangitis, a common cause of morbidity in podoconiosis patients
Profiling SO2 air pollution patterns in 9 EU Aphekom cities: The Aphekom Project
A detailed analysis of hourly pollutant concentrations mainly focusing on SO2 data obtained from 9 centres involved in the Aphekom project was conducted. This involved the generation of individual diurnal SO2 profiles in order to:
(i) identify city specific patterns including source apportionment and quantification,
(ii) track changes over time,
(iii) analyse the changes in SO2 concentrations from different emission sources, i.e. traffic, heating, shipping and industrial sources, overtime
Color Confinement, Quark Pair Creation and Dynamical Chiral-Symmetry Breaking in the Dual Ginzburg-Landau Theory
We study the color confinement, the - pair creation and the
dynamical chiral-symmetry breaking of nonperturbative QCD by using the dual
Ginzburg-Landau theory, where QCD-monopole condensation plays an essential role
on the nonperturbative dynamics in the infrared region. As a result of the dual
Meissner effect, the linear static quark potential, which characterizes the
quark confinement, is obtained in the long distance within the quenched
approximation. We obtain a simple expression for the string tension similar to
the energy per unit length of a vortex in the superconductivity physics. The
dynamical effect of light quarks on the quark confining potential is
investigated in terms of the infrared screening effect due to the -
pair creation or the cut of the hadronic string. The screening length of the
potential is estimated by using the Schwinger formula for the - pair
creation. We introduce the corresponding infrared cutoff to the strong
long-range correlation factor in the gluon propagator as a dynamical effect of
light quarks, and obtain a compact formula of the quark potential including the
screening effect in the infrared region. We investigate the dynamical
chiral-symmetry breaking by using the Schwinger-Dyson equation, where the gluon
propagator includes the nonperturbative effect related toComment: 37 pages, plain TeX (using `phyzzx' macro), (( 8 figures - available
on request from [email protected] )
The assessment of the implementation of fuel related legislations and their impact on air quality and public health
The main focus of Work Package 6 of the Aphekom project was: to develop innovative methods to analyse the decrease in air pollution levels following implementation of an European regulation to reduce the sulphur content in liquid fuels; to follow the evolution of health risks over time; to track related effect modifiers; and to quantify the monetary costs of health impacts of the implemented regulation
Mortality impacts of sulphur concetrations in 20 European cities in the APHEKOM Project
The implementation of three EU directives to reduce sulphur content in fuel was assessed for mortality impacts
in 20 European cities, between 1990 and 2007 in the APHEKOM project. This specific study aimed to examine whether different lag structures apply to the relationships between cardiovascular and respiratory events and SO2 concentrations, which will therefore result in differences in mortality impacts from regulation implementation. Prior evidence has shown that cardiovascular mortality is more likely to be affected by SO2 concentrations on the same or the previous day of the event, while respiratory mortality more likely to show a delayed effect of exposure to the same pollutant
Shoulder pain due to cervical radiculopathy: an underestimated long-term complication of herpes zoster virus reactivation?
Purpose
To evaluate if herpes zoster virus (HZV) reactivation may be considered in the aetiology of cervical radiculopathy.
Methods
The study group was composed of 110 patients (52 M-58F;mean age ± SD:46.5 ± 6.12; range:40-73) with a clinical diagnosis of cervical radiculopathy. Patients with signs of chronic damage on neurophysiological studies were submitted to an X-ray and to an MRI of the cervical spine in order to clarify the cause of the cervical radiculopathy and were investigated for a possible reactivation of HZV; HZV reactivation was considered as “recent” or “antique” if it occurs within or after 24 months from the onset of symptoms, respectively. Data were submitted to statistics.
Results
Thirty-eight patients (34,5%,16 M-22F) had a history of HZV reactivation: four (2 M-2F) were “recent” and 34 (14 M-20F) were “antique”. In 68 of 110 participants (61,8%,30 M-38F), pathological signs on X-ray and/or MRI of the cervical spine appeared; in the remaining 42 (38,2%,22 M-20F) X-ray and MRI resulted as negative. Among patients with HZV reactivation, seven (18,4%) had a “positive” X-ray-MRI while in 31 (81,6%) the instrumental exams were considered as negative. The prevalence of “antique” HZV reactivations was statistically greater in the group of patients with no pathological signs on X-ray/MRI of the cervical spine with respect to the group with a pathological instrumental exam (p < 0.01).
Conclusions
It may be useful to investigate the presence of a positive history of HZV reactivation and to consider it as a long-term complication of a cervical root inflammation especially in patients in which X-ray and MRI of the cervical spine did not show pathological findings
Effects of deceptive running speed on physiology, perceptual responses, and performance during sprint-distance triathlon
Objective
This study examined the effects of speed deception on performance, physiological and perceptual responses, and pacing during sprint-distance triathlon running.
Methods
Eight competitive triathletes completed three simulated sprint-distance triathlons (0.75 km swim, 20 km bike, 5 km run) in a randomised order, with swimming and cycling sections replicating baseline triathlon performance. During the first 1.66 km of the run participants maintained an imposed speed, completing the remaining 3.33 km as quickly as possible. Although participants were informed that initially prescribed running speed would reflect baseline performance, this was true during only one trial (Tri-Run100%). As such, other trials were either 3% faster (Tri-Run103%), or 3% slower (Tri-Run97%) than baseline during this initial period.
Results
Performance during Tri-Run103% (1346 ± 108 s) was likely faster than Tri-Run97% (1371 ± 108 s), and possibly faster than Tri-Run100% (1360 ± 125 s), with these differences likely to be competitively meaningful. The first 1.66 km of Tri-Run103% induced greater physiological strain compared to other conditions, whilst perceptual responses were not significantly different between trials.
Conclusions
It appears that even during ‘all-out’ triathlon running, athletes maintain some form of ‘reserve’ capacity which can be accessed by deception. This suggests that expectations and beliefs have a practically meaningful effect on pacing and performance during triathlon, although it is apparent that an individual’s conscious intentions are secondary to the brains sensitivity to potentially harmful levels of physiological and perceptual strain
Spatial and spectral features utilization on a hyperspectral imaging system for rice seed varietal purity inspection
A conventional method to inspect the varietal purity of rice seeds is based on evaluating human visual inspection where a random sample is drawn from a batch. This is a tedious, laborious, time consuming and extremely inefficient task. This paper presents an automatic rice seed inspection method using Hyperspectral imaging and machine learning, to automatically detect unwanted seeds from other varieties which may be contained in a batch. Hyperspectral image data from Near-infrared (NIR) and Visible cameras are acquired for six common rice seed varieties. The results of applying two classifiers are presented, a Support Vector Machine (SVM) and a Random Forest (RF), where each consists of six one-versus-rest binary classifiers. The results show that combining spectral and shape- based features derived from the rice seeds, increase precision of the multi-label classification to 84% compared 74% when only visual features are used
On the measurement of horizontal inequity in the delivery of health care
This paper offers a critical appraisal of the various methods used to date to investigate inequity in the delivery of health care. It concludes that none of the methods used to date is particularly well equipped to provide unbiassed estimates of the extent of inequity. It also concludes that Le Grand's (1978) approach is likely to point towards inequity favouring the rich even when none exists. The paper offers an alternative approach, which builds on the approaches to date but seeks to overcome their deficiencies
Dyson-Schwinger Equations: Density, Temperature and Continuum Strong QCD
Continuum strong QCD is the application of models and continuum quantum field
theory to the study of phenomena in hadronic physics, which includes; e.g., the
spectrum of QCD bound states and their interactions; and the transition to, and
properties of, a quark gluon plasma. We provide a contemporary perspective,
couched primarily in terms of the Dyson-Schwinger equations but also making
comparisons with other approaches and models. Our discourse provides a
practitioners' guide to features of the Dyson-Schwinger equations [such as
confinement and dynamical chiral symmetry breaking] and canvasses
phenomenological applications to light meson and baryon properties in cold,
sparse QCD. These provide the foundation for an extension to hot, dense QCD,
which is probed via the introduction of the intensive thermodynamic variables:
chemical potential and temperature. We describe order parameters whose
evolution signals deconfinement and chiral symmetry restoration, and chronicle
their use in demarcating the quark gluon plasma phase boundary and
characterising the plasma's properties. Hadron traits change in an equilibrated
plasma. We exemplify this and discuss putative signals of the effects. Finally,
since plasma formation is not an equilibrium process, we discuss recent
developments in kinetic theory and its application to describing the evolution
from a relativistic heavy ion collision to an equilibrated quark gluon plasma.Comment: 103 Pages, LaTeX, epsfig. To appear in Progress in Particle and
Nuclear Physics, Vol. 4
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