230 research outputs found
The mu - e Conversion in Nuclei, mu --> e gamma, mu --> 3e Decays and TeV Scale See-Saw Scenarios of Neutrino Mass Generation
We perform a detailed analysis of lepton flavour violation (LFV) within
minimal see-saw type extensions of the Standard Model (SM), which give a viable
mechanism of neutrino mass generation and provide new particle content at the
electroweak scale. We focus, mainly, on predictions and constraints set on each
scenario from mu --> e gamma, mu --> 3e and mu - e conversion in the nuclei. In
this class of models, the flavour structure of the Yukawa couplings between the
additional scalar and fermion representations and the SM leptons is highly
constrained by neutrino oscillation measurements. In particular, we show that
in some regions of the parameters space of type I and type II see-saw models,
the Dirac and Majorana phases of the neutrino mixing matrix, the ordering and
hierarchy of the active neutrino mass spectrum as well as the value of the
reactor mixing angle theta_{13} may considerably affect the size of the LFV
observables. The interplay of the latter clearly allows to discriminate among
the different low energy see-saw possibilities.Comment: Expressions for the factors |C_{me}|^2 and |C_{mu3e}|^2 in the mu-e
conversion and mu-->3e decay rates, eqs. (36) and (49), respectively,
corrected; results in subsections 2.2 and 2.3 quantitatively changed,
qualitatively remain the same; figures 2, 3, 4 and 5 replace
Parton coalescence at RHIC
Using a covariant coalescence model, we study hadron production in
relativistic heavy ion collisions from both soft partons in the quark-gluon
plasma and hard partons in minijets. Including transverse flow of soft partons
and independent fragmentation of minijet partons, the model is able to describe
available experimental data on pion, kaon, and antiproton spectra. The
resulting antiproton to pion ratio is seen to increase at low transverse
momenta and reaches a value of about one at intermediate transverse momenta, as
observed in experimental data at RHIC. A similar dependence of the antikaon to
pion ratio on transverse momentum is obtained, but it reaches a smaller value
at intermediate transverse momenta. At high transverse momenta, the model
predicts that both the antiproton to pion and the antikaon to pion ratio
decrease and approach those given by the perturbative QCD. Both collective flow
effect and coalescence of minijet partons with partons in the quark-gluon
plasma affect significantly the spectra of hadrons with intermediate transverse
momenta. Elliptic flows of protons, Lambdas, and Omegas have also been
evaluated from partons with elliptic flows extracted from fitting measured pion
and kaon elliptic flows, and they are found to be consistent with available
experimental data.Comment: 12 pages, 11 figure
Lepton flavor violating \u3c4 decays in TeV scale type i see-saw and Higgs triplet models
The lepton flavour violating (LFV) \u3c4 decays \u3c4 \u2192 (e, \u3bc)\u3b3 and \u3c4 \u2192 3\u3bc are investigated in the frameworks of the TeV scale type I see-saw and Higgs Triplet (or type II see-saw) models. Predictions for the rates of these processes are obtained. The implications of the existing stringent experimental upper bounds on the \u3bc \u2192 e + \u3b3 and \u3bc \u2192 3e decay branching ratios for the predictions of the \u3c4 \u2192 (e, \u3bc)\u3b3 and \u3c4 \u2192 3\u3bc decay rates are studied in detail. The possibilities to observe the indicated LFV \u3c4 decays in present and future experiments are analysed. \ua9 2013 SISSA, Trieste, Italy
Healthcare professionals' intentions to use wiki-based reminders to promote best practices in trauma care: a survey protocol
<p>Abstract</p> <p>Background</p> <p>Healthcare professionals are increasingly using wikis as collaborative tools to create, synthesize, share, and disseminate knowledge in healthcare. Because wikis depend on collaborators to keep content up-to-date, healthcare professionals who use wikis must adopt behaviors that foster this collaboration. This protocol describes the methods we will use to develop and test the metrological qualities of a questionnaire that will assess healthcare professionals' intentions and the determinants of those intentions to use wiki-based reminders that promote best practices in trauma care.</p> <p>Methods</p> <p>Using the Theory of Planned Behavior, we will conduct semi-structured interviews of healthcare professionals to identify salient beliefs that may affect their future use of wikis. These beliefs will inform our questionnaire on intended behavior. A test-retest of the survey will verify the questionnaire's stability over time. We will interview 50 healthcare professionals (25 physicians and 25 allied health professionals) working in the emergency departments of three trauma centers in Quebec, Canada. We will analyze the content of the interviews and construct and pilot a questionnaire. We will then test the revised questionnaire with 30 healthcare professionals (15 physicians and 15 allied health professionals) and retest it two weeks later. We will assess the internal consistency of the questionnaire constructs using Cronbach's alpha coefficients and determine their stability with the intra-class correlation (ICC).</p> <p>Discussion</p> <p>To our knowledge, this study will be the first to develop and test a theory-based survey that measures healthcare professionals' intentions to use a wiki-based intervention. This study will identify professionals' salient beliefs qualitatively and will quantify the psychometric capacities of the questionnaire based on those beliefs.</p
A prospective descriptive study of cryptococcal meningitis in HIV uninfected patients in Vietnam - high prevalence of Cryptococcus neoformans var grubii in the absence of underlying disease
<p>Abstract</p> <p>Background</p> <p>Most cases of cryptococcal meningitis occur in patients with HIV infection: the course and outcome of disease in the apparently immunocompetent is much more poorly understood. We describe a cohort of HIV uninfected Vietnamese patients with cryptococcal meningitis in whom underlying disease is uncommon, and relate presenting features of patients and the characteristics of the infecting species to outcome.</p> <p>Methods</p> <p>A prospective descriptive study of HIV negative patients with cryptococcal meningitis based at the Hospital for Tropical Diseases, Ho Chi Minh City. All patients had comprehensive clinical assessment at baseline, were cared for by a dedicated study team, and were followed up for 2 years. Clinical presentation was compared by infecting isolate and outcome.</p> <p>Results</p> <p>57 patients were studied. <it>Cryptococcus neoformans var grubii </it>molecular type VN1 caused 70% of infections; <it>C. gattii </it>accounted for the rest. Most patients did not have underlying disease (81%), and the rate of underlying disease did not differ by infecting species. 11 patients died while in-patients (19.3%). Independent predictors of death were age ≥ 60 years and a history of convulsions (odds ratios and 95% confidence intervals 8.7 (1 - 76), and 16.1 (1.6 - 161) respectively). Residual visual impairment was common, affecting 25 of 46 survivors (54.3%). Infecting species did not influence clinical phenotype or outcome. The minimum inhibitory concentrations of flucytosine and amphotericin B were significantly higher for <it>C. neoformans var grubii </it>compared with <it>C. gattii </it>(p < 0.001 and p = 0.01 respectively).</p> <p>Conclusion</p> <p>In HIV uninfected individuals in Vietnam, cryptococcal meningitis occurs predominantly in people with no clear predisposing factor and is most commonly due to <it>C. neoformans var grubii</it>. The rates of mortality and visual loss are high and independent of infecting species. There are detectable differences in susceptibility to commonly used antifungal drugs between species, but the clinical significance of this is not clear.</p
A Novel Tool for Online Community Moderator Evaluation
This study introduces a new instrument for leadership evaluation in online forums and other online communities which was developed using a grounded approach. Questions that emerged from the literature were then evaluated to create hypotheses that guided the development of an instrument for moderator evaluation. The Moderator Evaluation Contingency Scale (MECS) is modified from Fiedler’s contingency model to determine if a moderator is more task- or relationship-oriented in his
or her approach to moderation and interactions with other members of a community. The MECS was developed and tested on Reddit in 2013–2014 using random sampling for Forum selection, moderator selection, and interactions with users. A content analysis using the MECS to evaluate posts was found to be a viable measure of a moderator’s ability to
perform tasks like removing content as well as his or her ability to interact with users. Bots were analyzed using the MECS as well to determine bias. Next steps include making the instrument available for use by social media and niche community sites, administrators, and other moderators
Low-level regulatory T-cell activity is essential for functional type-2 effector immunity to expel gastrointestinal helminths
Helminth infection is frequently associated with the expansion of regulatory T cells (Tregs) and suppression of immune responses to bystander antigens. We show that infection of mice with the chronic gastrointestinal helminth Heligmosomoides polygyrus drives rapid polyclonal expansion of Foxp3(+)Helios(+)CD4(+) thymic (t)Tregs in the lamina propria and mesenteric lymph nodes while Foxp3(+)Helios(-)CD4(+) peripheral (p)Treg expand more slowly. Notably, in partially resistant BALB/c mice parasite survival positively correlates with Foxp3(+)Helios(+)CD4(+) tTreg numbers. Boosting of Foxp3(+)Helios(+)CD4(+) tTreg populations by administration of recombinant interleukin-2 (rIL-2):anti-IL-2 (IL-2C) complex increased worm persistence by diminishing type-2 responsiveness in vivo, including suppression of alternatively activated macrophage and granulomatous responses at the sites of infection. IL-2C also increased innate lymphoid cell (ILC) numbers, indicating that Treg functions dominate over ILC effects in this setting. Surprisingly, complete removal of Tregs in transgenic Foxp3-DTR mice also resulted in increased worm burdens, with "immunological chaos" evident in high levels of the pro-inflammatory cytokines IL-6 and interferon-γ. In contrast, worm clearance could be induced by anti-CD25 antibody-mediated partial depletion of early Treg, alongside increased T helper type 2 responses and without incurring pathology. These findings highlight the overarching importance of the early Treg response to infection and the non-linear association between inflammation and the prevailing Treg frequency
- …