1,958 research outputs found

    Higgs decay with monophoton + MET signature from low scale supersymmetry breaking

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    We study the decay of a standard model-like Higgs boson into a gravitino and a neutralino, which subsequently decays promptly into another gravitino and a photon. Such a decay can be important in scenarios where the supersymmetry breaking scale is of the order of a few TeV, and in the region of low transverse momenta of the photon, it may provide the dominant contribution to the final state with a photon and two gravitinos. We estimate the relevant standard model backgrounds and the prospects for discovering this Higgs decay through a photon and missing transverse energy signal at the LHC in terms of a simplified model. We also give an explicit model with manifest, but spontaneously broken, supersymmetry in which the usual MSSM soft terms are promoted to supersymmetric operators involving a dynamical goldstino supermultiplet. This model can give rise to a SM-like CP-even neutral Higgs particle with a mass of 125 GeV, without requiring substantial radiative corrections, and with couplings sufficiently large for a signal discovery through the above mentioned Higgs decay channel with the upcoming data from the LHC.Comment: 28 pages, 5 figures, 4 tables; v2: updated to JHEP version, references adde

    Quantization of Midisuperspace Models

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    We give a comprehensive review of the quantization of midisuperspace models. Though the main focus of the paper is on quantum aspects, we also provide an introduction to several classical points related to the definition of these models. We cover some important issues, in particular, the use of the principle of symmetric criticality as a very useful tool to obtain the required Hamiltonian formulations. Two main types of reductions are discussed: those involving metrics with two Killing vector fields and spherically symmetric models. We also review the more general models obtained by coupling matter fields to these systems. Throughout the paper we give separate discussions for standard quantizations using geometrodynamical variables and those relying on loop quantum gravity inspired methods.Comment: To appear in Living Review in Relativit

    Structured feedback on students’ concept maps: the proverbial path to learning?

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    Good conceptual knowledge is an essential requirement for health professions students, in that they are required to apply concepts learned in the classroom to a variety of different contexts. However, the use of traditional methods of assessment limits the educator’s ability to correct students’ conceptual knowledge prior to altering the educational context. Concept mapping (CM) is an educational tool for evaluating conceptual knowledge, but little is known about its use in facilitating the development of richer knowledge frameworks. In addition, structured feedback has the potential to develop good conceptual knowledge. The purpose of this study was to use Kinchin’s criteria to assess the impact of structured feedback on the graphical complexity of CM’s by observing the development of richer knowledge frameworks. Fifty-eight physiotherapy students created CM’s targeting the integration of two knowledge domains within a case-based teaching paradigm. Each student received one round of structured feedback that addressed correction, reinforcement, forensic diagnosis, benchmarking, and longitudinal development on their CM’s prior to the final submission. The concept maps were categorized according to Kinchin’s criteria as either Spoke, Chain or Net representations, and then evaluated against defined traits of meaningful learning. The inter-rater reliability of categorizing CM’s was good. Pre-feedback CM’s were predominantly Chain structures (57%), with Net structures appearing least often. There was a significant reduction of the basic Spoke- structured CMs (P = 0.002) and a significant increase of Net-structured maps (P < 0.001) at the final evaluation (post-feedback). Changes in structural complexity of CMs appeared to be indicative of broader knowledge frameworks as assessed against the meaningful learning traits. Feedback on CM’s seemed to have contributed towards improving conceptual knowledge and correcting naive conceptions of related knowledge. Educators in medical education could therefore consider using CM’s to target individual student development

    The “Far-West” of Anopheles gambiae Molecular Forms

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    The main Afrotropical malaria vector, Anopheles gambiae sensu stricto, is undergoing a process of sympatric ecological diversification leading to at least two incipient species (the M and S molecular forms) showing heterogeneous levels of divergence across the genome. The physically unlinked centromeric regions on all three chromosomes of these closely related taxa contain fixed nucleotide differences which have been found in nearly complete linkage disequilibrium in geographic areas of no or low M-S hybridization. Assays diagnostic for SNP and structural differences between M and S forms in the three centromeric regions were applied in samples from the western extreme of their range of sympatry, the only area where high frequencies of putative M/S hybrids have been reported. The results reveal a level of admixture not observed in the rest of the range. In particular, we found: i) heterozygous genotypes at each marker, although at frequencies lower than expected under panmixia; ii) virtually all possible genotypic combinations between markers on different chromosomes, although genetic association was nevertheless detected; iii) discordant M and S genotypes at two X-linked markers near the centromere, suggestive of introgression and inter-locus recombination. These results could be indicative either of a secondary contact zone between M and S, or of the maintenance of ancestral polymorphisms. This issue and the perspectives opened by these results in the study of the M and S incipient speciation process are discussed

    Quantum Gravity in 2+1 Dimensions: The Case of a Closed Universe

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    In three spacetime dimensions, general relativity drastically simplifies, becoming a ``topological'' theory with no propagating local degrees of freedom. Nevertheless, many of the difficult conceptual problems of quantizing gravity are still present. In this review, I summarize the rather large body of work that has gone towards quantizing (2+1)-dimensional vacuum gravity in the setting of a spatially closed universe.Comment: 61 pages, draft of review for Living Reviews; comments, criticisms, additions, missing references welcome; v2: minor changes, added reference

    Mobility, Expansion and Management of a Multi-Species Scuba Diving Fishery in East Africa

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    Background: Scuba diving fishing, predominantly targeting sea cucumbers, has been documented to occur in an uncontrolled manner in the Western Indian Ocean and in other tropical regions. Although this type of fishing generally indicates a destructive activity, little attention has been directed towards this category of fishery, a major knowledge gap and barrier to management. Methodology and Principal Findings: With the aim to capture geographic scales, fishing processes and social aspects the scuba diving fishery that operate out of Zanzibar was studied using interviews, discussions, participant observations and catch monitoring. The diving fishery was resilient to resource declines and had expanded to new species, new depths and new fishing grounds, sometimes operating approximately 250 km away from Zanzibar at depths down to 50 meters, as a result of depleted easy-access stock. The diving operations were embedded in a regional and global trade network, and its actors operated in a roving manner on multiple spatial levels, taking advantage of unfair patron-client relationships and of the insufficient management in Zanzibar. Conclusions and Significance: This study illustrates that roving dynamics in fisheries, which have been predominantly addressed on a global scale, also take place at a considerably smaller spatial scale. Importantly, while proposed management of the sea cucumber fishery is often generic to a simplified fishery situation, this study illustrates

    Teaching Medicine to Non-English Speaking Background Learners in a Foreign Country

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    Teaching abroad exposes medical educators to unfamiliar teaching methods and learning styles that can enhance their overall teaching repertoire. Based on the author’s experience teaching residents for one month at a community hospital in Japan and a review of the non-English speaking background (NESB) educational literature, pedagogical principles and lessons for successful international NESB instruction are outlined. These methods include understanding the dissimilar linguistic, cultural, and academic backgrounds of the learners, emphasizing pace and clarity of speech, presenting a conceptual framework instead of detailed discourse on subjects, and regular visual reinforcement of spoken words. The limitations introduced by the language barrier and the use of interpreters are briefly discussed. As society and institutions of higher learning become more global and multicultural, clinician–educators may benefit from teaching in other countries in order to enhance their teaching skills with NESB learners, both abroad and in their own institutions

    Antitubercular therapy decreases nitric oxide production in HIV/TB coinfected patients

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    BACKGROUND: Nitric oxide (NO) production is increased among patients with human immunodeficiency virus (HIV) infection and also among those with tuberculosis (TB). In this study we sought to determine if there was increased NO production among patients with HIV/TB coinfection and the effect of four weeks chemotherapy on this level. METHODS: 19 patients with HIV/TB coinfection were studied. They were treated with standard four drug antitubercular therapy and sampled at baseline and four weeks. 20 patients with HIV infection, but no opportunistic infections, were disease controls and 20 individuals were healthy controls. Nitrite and citrulline, surrogate markers for NO, were measured spectrophotometrically. RESULTS: The mean age of HIV/TB patients was 28.4 ± 6.8 years and CD4 count was 116 ± 36.6/mm. Mean nitrite level among HIV/TB coinfected was 207.6 ± 48.8 nmol/ml. This was significantly higher than 99.7 ± 26.5 nmol/ml, the value for HIV infected without opportunistic infections and 46.4 ± 16.2 nmol/ml, the value for healthy controls (p value < 0.01). The level of HIV/TB coinfected NO in patients declined to 144.5 ± 34.4 nmol/ml at four weeks of therapy (p value < 0.05). Mean citrulline among HIV/TB coinfected was 1446.8 ± 468.8 nmol/ml. This was significantly higher than 880.8 ± 434.8 nmol/ml, the value for HIV infected without opportunistic infections and 486.6 ± 212.5 nmol/ml, the value for healthy controls (p value < 0.01). Levels of citrolline in HIV/TB infected declined to 1116.2 ± 388.6 nmol/ml at four weeks of therapy (p value < 0.05). CONCLUSIONS: NO production is elevated among patients with HIV infection, especially so among HIV/TB coinfected patients, but declines significantly following 4 weeks of antitubercular therapy

    Recovery of Meteorological Data for the Observatory of A Guarda, Spain

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    We herein describe the recovery of a series of data on temperature, humidity, precipitation, evaporation, wind, and local weather conditions from documentary sources obtained from the Jesuit observatory of A Guarda (Galicia, Spain) for the period 1881–1896. The data were digitized and made available in accessible electronic formats. Comparisons were made with present-day meteorological data obtained from two nearby stations. We further believe that the discovery of some new complementary documentary sources made during the present research could be a basis for future data recovery efforts. Among these new results, early ozone data from the period are of outstanding importance to meteorologists

    Socio-demographic determinants of coinfections by HIV, hepatitis B and hepatitis C viruses in central Italian prisoners

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    BACKGROUND: The coinfections HIV/HCV/HBV are an important health issue in penitentiary communities. The aim of the study was to examine HIV, HBV and HCV coinfections determinants amongst prisoners in the jails of Southern Lazio (Central Italy), in the period 1995-2000. METHODS: Diagnosis of seropositivities for HIV, HBV and HCV was made using ELISA method. A multiple logistic regression analysis was conducted to verify the influence of socio-demographic factors on the HIV/HBV/HCV coinfections. RESULTS: HIV/HCV, HBV/HCV and HIV/HBV coinfections were detected in 42 (4%), 203 (17.9%) and 31 (2.9%) inmates, respectively. These coinfections are significantly associated with the status of drug addiction (OR = 16.02; p = 0.012; OR = 4.15; p &lt; 0.001; OR = 23.57; p = 0.002), smoking habits (OR = 3.73; p = 0.033; OR = 1.42; p = 0.088; OR = 4.25; p = 0.053) and Italian nationality (OR = 7.05; p = 0.009; OR = 2.31; p &lt; 0.001; OR = 4.61; p = 0.04). CONCLUSION: The prevalence of HIV, HBV and HCV seropositivity in jails suggests that information and education programs for inmates could be useful to reduce the spread of such infections
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