252 research outputs found
Assessing Risk in Focal Arboviral Infections: Are We Missing the Big or Little Picture?
Focal arboviral infections affecting a subset of the overall population present an often overlooked set of challenges in the assessment and reporting of risk and the detection of spatial patterns. Our objective was to assess the variation in risk when using different at-risk populations and geographic scales for the calculation of incidence risk and the detection of geographic hot-spots of infection. We explored these variations using a pediatric arbovirus, La Crosse virus (LACV), as our model.Descriptive and cluster analyses were performed on probable and confirmed cases of LACV infections reported to the Tennessee Department of Health from 1997 to 2006, using three at-risk populations (the total population, the population 18 years and younger, and the population 15 years and younger) and at two geographic levels (county and census tract) to assess the variation in incidence risk and to investigate evidence of clustering using both global and local spatial statistics. We determined that the most appropriate at-risk population to calculate incidence risk and to assess the evidence of clustering was the population 15 years and younger. Based on our findings, the most appropriate geographical level to conduct spatial analyses and report incidence risk is the census tract level. The incidence risk in the population 15 years and younger at the county level ranged from 0 to 226.5 per 100,000 persons (median 41.5) in those counties reporting cases (nâ=â14) and at the census tract level it ranged from 50.9 to 673.9 per 100,000 persons (median 126.7) in those census tracts reporting cases (nâ=â51). To our knowledge, this is the highest reported incidence risk for this population at the county level for Tennessee and at the census tract level nationally.The results of this study indicate the possibility of missing disease clusters resulting from performing incidence risk investigations of focal diseases using inappropriate at-risk populations and/or at large geographic scales. Improved disease surveillance and health planning will result through the use of well defined at-risk populations and the use of appropriate geographic scales for the analysis and reporting of diseases. The finding of a high incidence risk of LACV infections in eastern Tennessee demonstrates that the vast majority of these infections continue to be under-diagnosed and/or underreported in this region. Persistent prevention and surveillance efforts will be required to reduce exposure to infectious vectors and to detect new cases of infection in this region. Application of this study's observations in future investigations will enhance the quantification of incidence risk and the identification of high-risk groups within the population
An Exploratory Descriptive Study of Antimicrobial Resistance Patterns of Staphylococcus Spp. Isolated from Horses Presented at a Veterinary Teaching Hospital
Background
Antimicrobial resistant Staphylococcus are becoming increasingly important in horses because of the zoonotic nature of the pathogens and the associated risks to caregivers and owners. Knowledge of the burden and their antimicrobial resistance patterns are important to inform control strategies. This study is an exploratory descriptive investigation of the burden and antimicrobial drug resistance patterns of Staphylococcus isolates from horses presented at a veterinary teaching hospital in South Africa. Methods
Retrospective laboratory clinical records of 1027 horses presented at the University of Pretoria veterinary teaching hospital between 2007 and 2012 were included in the study. Crude and factor-specific percentages of Staphylococcus positive samples, antimicrobial resistant (AMR) and multidrug resistant (MDR) isolates were computed and compared across Staphylococcus spp., geographic locations, seasons, years, breed and sex using Chi-square and Fisherâs exact tests. Results
Of the 1027 processed clinical samples, 12.0% were Staphylococcus positive. The majority of the isolates were S. aureus (41.5%) followed by S. pseudintermedius(14.6%). Fifty-two percent of the Staphylococcus positive isolates were AMR while 28.5% were MDR. Significant (p \u3c 0.05) differences in the percentage of samples with isolates that were AMR or MDR was observed across seasons, horse breeds and Staphylococcus spp. Summer season had the highest (64.3%) and autumn the lowest (29.6%) percentages of AMR isolates. Highest percentage of AMR samples were observed among the Boerperds (85.7%) followed by the American saddler (75%) and the European warm blood (73.9%). Significantly (p \u3c 0.001) more S. aureus isolates (72.5%) were AMR than S. pseudintermedius isolates (38.9%). Similarly, significantly (p \u3c 0.001) more S. aureus (52.9%) exhibited MDR than S. pseudintermedius (16.7%). The highest levels of AMR were towards ÎČ-lactams (84.5%) followed by trimethoprim/sulfamethoxazole (folate pathway inhibitors) (60.9%) while the lowest levels of resistance were towards amikacin (14.%). Conclusions
This exploratory study provides useful information to guide future studies that will be critical for guiding treatment decisions and control efforts. There is a need to implement appropriate infection control, and judicious use of antimicrobials to arrest development of antimicrobial resistance. A better understanding of the status of the problem is a first step towards that goal
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Femtoscopy with identified charged pions in proton-lead collisions at âsNN =5.02 TeV with ATLAS
Bose-Einstein correlations between identified charged pions are measured for
+Pb collisions at TeV using data recorded by
the ATLAS detector at the LHC corresponding to a total integrated luminosity of
. Pions are identified using ionization energy loss
measured in the pixel detector. Two-particle correlation functions and the
extracted source radii are presented as a function of collision centrality as
well as the average transverse momentum () and rapidity
() of the pair. Pairs are selected with a rapidity and with an average transverse momentum GeV. The effect of jet fragmentation on the two-particle
correlation function is studied, and a method using opposite-charge pair data
to constrain its contributions to the measured correlations is described. The
measured source sizes are substantially larger in more central collisions and
are observed to decrease with increasing pair . A correlation
of the radii with the local charged-particle density is demonstrated. The
scaling of the extracted radii with the mean number of participating nucleons
is also used to compare a selection of initial-geometry models. The cross-term
is measured as a function of rapidity, and a nonzero value is
observed with combined significance for in the most central events
Echocardiography in patients with hypertrophic cardiomyopathy: usefulness of old and new techniques in the diagnosis and pathophysiological assessment
Hypertrophic cardiomyopathy (HCM) is one of the most common inherited cardiomyopathy. The identification of patients with HCM is sometimes still a challenge. Moreover, the pathophysiology of the disease is complex because of left ventricular hyper-contractile state, diastolic dysfunction, ischemia and obstruction which can be coexistent in the same patient. In this review, we discuss the current and emerging echocardiographic methodology that can help physicians in the correct diagnostic and pathophysiological assessment of patients with HCM
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Combination of searches for WW, WZ, and ZZ resonances in pp collisions at s=8 TeV with the ATLAS detector
The ATLAS experiment at the CERN Large Hadron Collider has performed searches for new, heavy bosons decaying to WW, WZ and ZZ final states in multiple decay channels using 20.3 fb-1 of pp collision data at s=8 TeV. In the current study, the results of these searches are combined to provide a more stringent test of models predicting heavy resonances with couplings to vector bosons. Direct searches for a charged diboson resonance decaying to WZ in the âÎœâ'â' (â=ÎŒ, e), ââqq-, âÎœqq- and fully hadronic final states are combined and upper limits on the rate of production times branching ratio to the WZ bosons are compared with predictions of an extended gauge model with a heavy W' boson. In addition, direct searches for a neutral diboson resonance decaying to WW and ZZ in the ââqq-, âÎœqq-, and fully hadronic final states are combined and upper limits on the rate of production times branching ratio to the WW and ZZ bosons are compared with predictions for a heavy, spin-2 graviton in an extended Randall-Sundrum model where the Standard Model fields are allowed to propagate in the bulk of the extra dimension
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A measurement of material in the ATLAS tracker using secondary hadronic interactions in 7TeV pp collisions
Knowledge of the material in the ATLAS inner tracking detector is crucial in
understanding the reconstruction of charged-particle tracks, the performance of
algorithms that identify jets containing b-hadrons and is also essential to
reduce background in searches for exotic particles that can decay within the
inner detector volume. Interactions of primary hadrons produced in pp
collisions with the material in the inner detector are used to map the location
and amount of this material. The hadronic interactions of primary particles may
result in secondary vertices, which in this analysis are reconstructed by an
inclusive vertex-finding algorithm. Data were collected using minimum-bias
triggers by the ATLAS detector operating at the LHC during 2010 at
centre-of-mass energy = 7 TeV, and correspond to an integrated
luminosity of nb. Kinematic properties of these secondary vertices
are used to study the validity of the modelling of hadronic interactions in
simulation. Secondary-vertex yields are compared between data and simulation
over a volume of about 0.7 m around the interaction point, and agreement is
found within overall uncertainties
Search for anomalous couplings in the W tb vertex from the measurement of double differential angular decay rates of single top quarks produced in the t-channel with the ATLAS detector
The electroweak production and subsequent decay of single top quarks is determined by the properties of the Wtb vertex. This vertex can be described by the complex parameters of an effective Lagrangian. An analysis of angular distributions of the decay products of single top quarks produced in the t -channel constrains these parameters simultaneously. The analysis described in this paper uses 4.6 fbâ1 of proton-proton collision data at âs =7 TeV collected with the ATLAS detector at the LHC. Two parameters are measured simultaneously in this analysis. The fraction f 1 of decays containing transversely polarised W bosons is measured to be 0.37 ± 0.07 (stat.âsyst.). The phase ÎŽ â between amplitudes for transversely and longitudinally polarised W bosons recoiling against left-handed b-quarks is measured to be â0.014Ï Â± 0.036Ï (stat.âsyst.). The correlation in the measurement of these parameters is 0.15. These values result in two-dimensional limits at the 95% confidence level on the ratio of the complex coupling parameters g R and V L, yielding Re[g R /V L] â [â0.36, 0.10] and Im[g R /V L] â [â0.17, 0.23] with a correlation of 0.11. The results are in good agreement with the predictions of the Standard Model
Charged-particle distributions at low transverse momentum in âs=13 13 TeV pp interactions measured with the ATLAS detector at the LHC
Measurements of distributions of charged particles produced in protonâproton collisions with a centre-of-mass energy of 13 TeV are presented. The data were recorded by the ATLAS detector at the LHC and correspond to an integrated luminosity of 151 ÎŒb â1 ÎŒbâ1 . The particles are required to have a transverse momentum greater than 100 MeV and an absolute pseudorapidity less than 2.5. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity and the dependence of the mean transverse momentum on multiplicity are measured in events containing at least two charged particles satisfying the above kinematic criteria. The results are corrected for detector effects and compared to the predictions from several Monte Carlo event generators
Measurement of the inelastic proton-proton cross section at âs=13 TeV with the ATLAS detector at the LHC
This Letter presents a measurement of the inelastic proton-proton cross section using 60ââÎŒb â1 of pp collisions at a center-of-mass energy âs of 13 TeV with the ATLAS detector at the LHC. Inelastic interactions are selected using rings of plastic scintillators in the forward region (2.0710 â6 , where M X is the larger invariant mass of the two hadronic systems separated by the largest rapidity gap in the event. In this Ο range the scintillators are highly efficient. For diffractive events this corresponds to cases where at least one proton dissociates to a system with M X >13ââGeV . The measured cross section is compared with a range of theoretical predictions. When extrapolated to the full phase space, a cross section of 78.1±2.9ââmb is measured, consistent with the inelastic cross section increasing with center-of-mass energy
Search for pair production of Higgs bosons in the bbÂŻbbÂŻ final state using proton-proton collisions at âs=13ââTeV with the ATLAS detector
A search for Higgs-boson pair production in the bb ÂŻ bb ÂŻ final state is carried out with 3.2ââfb â1 of proton-proton collision data collected at s â =13ââTeV with the ATLAS detector. The data are consistent with the estimated background and are used to set upper limits on the production cross section of Higgs-boson pairs times branching ratio to bb ÂŻ bb ÂŻ for both nonresonant and resonant production. In the case of resonant production of Kaluza-Klein gravitons within the Randall-Sundrum model, upper limits in the 24 to 91 fb range are obtained for masses between 600 and 3000 GeV, at the 95% confidence level. The production cross section times branching ratio for nonresonant Higgs-boson pairs is also constrained to be less than 1.22 pb, at the 95% confidence level
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