354 research outputs found

    Evolution of parasite virulence to vectors

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    Vectorborne parasites are commonly predicted to be less virulent to the vector than to the definitive host as the parasite gains little by harming its main route of transmission. Here we assess the empirical evidence from systems where insects vector vertebrate parasites. The body of evidence supports lower (but non-zero) parasite virulence to vectors than to plant or invertebrate hosts but not to vertebrate hosts. We consider why this might be by assessing evolutionarily stable strategies for an insect parasite that can infect both vector and definitive host and can have distinct virulences in these two potential hosts. In a homogeneous environment the parasite is predicted to be equally virulent to vector and host. However, in a patchy environment it is predicted to become benign towards the more mobile of the two potential hosts, provided competitive displacement among strains in a patch is weak. This prediction may not meet reality for two different reasons. First, relative mobility of vector to host depends on the spatial scale under consideration: malaria mosquitoes are the more mobile hosts from house to house within a human settlement, but human hosts may be more mobile from one settlement to the other. Second, as in malaria, the main host and therefore probably also the vector may be multiply infected and this is likely to increase virulence and to level off differences between vector and definitive hos

    Asymptotics and local constancy of characters of p-adic groups

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    In this paper we study quantitative aspects of trace characters Θπ\Theta_\pi of reductive pp-adic groups when the representation π\pi varies. Our approach is based on the local constancy of characters and we survey some other related results. We formulate a conjecture on the behavior of Θπ\Theta_\pi relative to the formal degree of π\pi, which we are able to prove in the case where π\pi is a tame supercuspidal. The proof builds on J.-K.~Yu's construction and the structure of Moy-Prasad subgroups.Comment: Proceedings of Simons symposium on the trace formul

    Microvascular complications at time of diagnosis of type 2 diabetes are similar among diabetic patients detected by targeted screening and patients newly diagnosed in general practice - The Hoorn Screening Study

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    OBJECTIVE - To investigate whether screening-detected diabetic patients differ from diabetic patients newly diagnosed in general practice with regard to the presence of microvascular complications. RESEARCH AND DESIGN METHODS - Diabetic patients, identified by a population-based targeted screening procedure consisting of a screening questionnaire and a fasting capillary whole-blood glucose measurement followed by diagnostic testing, were compared with patients newly diagnosed with diabetes in general practice. Retinopathy was assessed with fundus photography, impaired foot sensitivity was assessed with Semmes-Weinstein monofilaments, and the presence of microalbuminuria was measured by means of the albumin-to creatinine ratio (ACR). RESULTS - A total of 195 screening-detected type 2 diabetic patients and 60 patients newly diagnosed in general practice participated in the medical examination. The prevalence of retinopathy was higher in screening-detected type 2 diabetic patients than in patients newly diagnosed in general practice, but not significantly higher. The prevalence of retinopathy was 7.6% (95% CI 4.6-12.4) in screening-detected type 2 diabetic patients and 1.9% (0.3-9.8) in patients newly diagnosed in general practice. The prevalence of impaired foot sensitivity was similar in both groups, 48.1% (40.9-55.3) and 48.3% (36.2-60.7), respectively. The ACR was 0.61 (interquariile range 0.41-1.50) in screening-detected type 2 diabetic patients and 0.99 (0.53-2.49) in patients newly diagnosed in general practice. The difference in prevalence of microalbuminuria was not statistically significant. The prevalence of microalbuminuria was 17.2% (95% CI 12.5-23.2) and 26.7% (17.1-39.0) in screening-detected type 2 diabetic patients and patients newly diagnosed in general practice, respectively. CONCLUSIONS - Targeted screening for type 2 diabetes (with a screening questionnaire as a first step) resulted in the identification of previously undiagnosed diabetic patients with a considerable prevalence of microvascular complications

    Probing exotic phenomena at the interface of nuclear and particle physics with the electric dipole moments of diamagnetic atoms: A unique window to hadronic and semi-leptonic CP violation

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    The current status of electric dipole moments of diamagnetic atoms which involves the synergy between atomic experiments and three different theoretical areas -- particle, nuclear and atomic is reviewed. Various models of particle physics that predict CP violation, which is necessary for the existence of such electric dipole moments, are presented. These include the standard model of particle physics and various extensions of it. Effective hadron level combined charge conjugation (C) and parity (P) symmetry violating interactions are derived taking into consideration different ways in which a nucleon interacts with other nucleons as well as with electrons. Nuclear structure calculations of the CP-odd nuclear Schiff moment are discussed using the shell model and other theoretical approaches. Results of the calculations of atomic electric dipole moments due to the interaction of the nuclear Schiff moment with the electrons and the P and time-reversal (T) symmetry violating tensor-pseudotensor electron-nucleus are elucidated using different relativistic many-body theories. The principles of the measurement of the electric dipole moments of diamagnetic atoms are outlined. Upper limits for the nuclear Schiff moment and tensor-pseudotensor coupling constant are obtained combining the results of atomic experiments and relativistic many-body theories. The coefficients for the different sources of CP violation have been estimated at the elementary particle level for all the diamagnetic atoms of current experimental interest and their implications for physics beyond the standard model is discussed. Possible improvements of the current results of the measurements as well as quantum chromodynamics, nuclear and atomic calculations are suggested.Comment: 46 pages, 19 tables and 16 figures. A review article accepted for EPJ

    Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

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    Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

    Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV

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    Results are presented from a search for a W' boson using a dataset corresponding to 5.0 inverse femtobarns of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV. The W' boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both left-handed and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W' to t b, leading to a final state signature with a single lepton (e, mu), missing transverse energy, and jets, at least one of which is tagged as a b-jet. A W' boson that couples to fermions with the same coupling constant as the W, but to the right-handed rather than left-handed chiral projections, is excluded for masses below 1.85 TeV at the 95% confidence level. For the first time using LHC data, constraints on the W' gauge coupling for a set of left- and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe

    Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV

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    A search for a Higgs boson decaying into two photons is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross section of the standard model Higgs boson decaying to two photons. The expected exclusion limit at 95% confidence level is between 1.4 and 2.4 times the standard model cross section in the mass range between 110 and 150 GeV. The analysis of the data excludes, at 95% confidence level, the standard model Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The largest excess of events above the expected standard model background is observed for a Higgs boson mass hypothesis of 124 GeV with a local significance of 3.1 sigma. The global significance of observing an excess with a local significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is estimated to be 1.8 sigma. More data are required to ascertain the origin of this excess.Comment: Submitted to Physics Letters
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