948 research outputs found

    On special quadratic birational transformations of a projective space into a hypersurface

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    We study transformations as in the title with emphasis on those having smooth connected base locus, called "special". In particular, we classify all special quadratic birational maps into a quadric hypersurface whose inverse is given by quadratic forms by showing that there are only four examples having general hyperplane sections of Severi varieties as base loci.Comment: Accepted for publication in Rendiconti del Circolo Matematico di Palerm

    NEW SEISMIC SOURCE ZONE MODEL FOR PORTUGAL AND AZORES

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    The development of seismogenic source models is one of the first steps in seismic hazard assessment. In seismic hazard terminology, seismic source zones (SSZ) are polygons (or volumes) that delineate areas with homogeneous characteristics of seismicity. The importance of using knowledge on geology, seismicity and tectonics in the definition of source zones has been recognized for a long time [1]. However, the definition of SSZ tends to be subjective and controversial. Using SSZ based on broad geology, by spreading the seismicity clusters throughout the areal extent of a zone, provides a way to account for possible long-term non-stationary seismicity behavior [2,3]. This approach effectively increases seismicity rates in regions with no significant historical or instrumental seismicity, while decreasing seismicity rates in regions that display higher rates of seismicity. In contrast, the use of SSZ based on concentrations of seismicity or spatial smoothing results in stationary behavior [4]. In the FP7 Project SHARE (Seismic Hazard Harmonization in Europe), seismic hazard will be assessed with a logic tree approach that allows for three types of branches for seismicity models: a) smoothed seismicity, b) SSZ, c) SSZ and faults. In this context, a large-scale zonation model for use in the smoothed seismicity branch, and a new consensus SSZ model for Portugal and Azores have been developed. The new models were achieved with the participation of regional experts by combining and adapting existing models and incorporating new regional knowledge of the earthquake potential. The main criteria used for delineating the SSZ include distribution of seismicity, broad geological architecture, crustal characteristics (oceanic versus continental, tectonically active versus stable, etc.), historical catalogue completeness, and the characteristics of active or potentially-active faults. This model will be integrated into an Iberian model of SSZ to be used in the Project SHARE seismic hazard assessment

    Poverty, Partner Discord, and Divergent Accounts; A Mixed Methods Account of Births before Arrival to Health Facilities in Morogoro Region, Tanzania.

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    Births before arrival (BBA) to health care facilities are associated with higher rates of perinatal morbidity and mortality compared to facility deliveries or planned home births. Research on such births has been conducted in several high-income countries, but there are almost no studies from low-income settings where a majority of maternal and newborn deaths occur. Drawing on a household survey of women and in-depth interviews with women and their partners, we examined the experience of BBA in rural districts of Morogoro Region, Tanzania. Among survey respondents, 59 births (4 %) were classified as BBAs. Most of these births occurred in the presence of a family member (47 %) or traditional birth attendant (24 %). Low socioeconomic status was the strongest predictor of BBA. After controlling for wealth via matching, high parity and a low number of antenatal care (ANC) visits retained statistical significance. While these variables are useful indicators of which women are at greater risk of BBA, their predictive power is limited in a context where many women are poor, multiparous, and make multiple ANC visits. In qualitative interviews, stories of BBAs included themes of partner disagreement regarding when to depart for facilities and financial or logistical constraints that underpinned departure delays. Women described wanting to depart earlier to facilities than partners. As efforts continue to promote facility birth, we highlight the financial demands associated with facility delivery and the potential for these demands to place women at a heightened risk for BBAs

    Sexually transmissible infections among young adolescents in Milan areas: a multicentre study

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    Objective: Sexually transmitted infections (STIs) are a major health problem affecting mostly young people, the exact magnitude of STIs is frequently unknown due to lack of country surveillance systems. Aim of this study was to determine the prevalence of STIs and relative risk factors among and adolescents in Milan areas, Italy. Methods: From May to October 2011, 117 adolescents (63 female, 54%), median age 15 years, attending hospitals from the north-western areas of Milan, Italy, were enrolled. All subjects completed a questionnaire and provided a urine sample, which was tested for Neisseria gonorrhea, Chlamidia trachomatis, Mycoplasma hominis, Mycoplasma genitalium, Ureaplasma urealyticum/parvum, Trichomonas vaginalis, Treponema pallidum, Streptococcus agalatiae, Haemophylus ducrey, Citomegalovirus (CMV), Herpes Simplex Virus 1(HSV1) and Lymphogranuloma venereum by a multiplex PCR assay: Seeplex\uae STI Master ACE Detection (Seegene, Seoul, Korea). Forty tree out of 117 adolescents (36%) were HIV-1 positive, 63% (74/117) were without any underlying infectious disease. Results: Fifty seven (48,7%) out of 117 adolescent were sexually active (SA), 20 out of 57 (35%) had STIs as follow: 24.5% (14 cases) U.urealyticum/parvum, 7% (4cases) C.trachomatis, 1.7% (one case each) M. genitalium and N.gonorrhoea. Thirty-two (56%) out of 57 SA adolescents were HIV-1 positive and infected with U. urealyticum/parvum (37.5%, 12 cases) and C.trachomatis (6.2% 2 cases). A single case (3.1%) of mixed infection due to C.trachomatis, N.gonorrhoea and U.urealyticum/parvum was observed. Six out of 60 (10%) sexually inactive (SI) adolescents resulted positive for U.urealyticum/parvum (3 cases), C.trachomatis (2 cases) and N.gonorrhoea (1 case). Eleven out of 60 were HIV-1 positive and among this group one case of C.trachomatis and U.urealyticum/parvum infection was reported. For T.vaginalis, T. pallidum, S. agalatiae, H.ducrey, CMV, HSV1 and Lymphogranuloma venereum any infection was reported. Conclusion: STIs as expected were higher in SA adolescent than in SI and in HIV-1 positive patients (P <0.025).Twenty-two percent of SA adolescents resulted positive for at least one STIs. A prevalence of 14.5% (17/117) for U. urealyticum/parvum, was detected in the adolescents studied, even if its clinical significance has yet to be assessed. Findings suggest that surveillance and screening programs should be implemented to prevent sequels on this vulnerable population

    Incorporating Descriptive Metadata into Seismic Source Zone Models for Seismic Hazard Assessment: A case study of the Azores-West Iberian region

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    In probabilistic seismic-hazard analysis (PSHA), seismic source zone (SSZ) models are widely used to account for the contribution to the hazard from earth- quakes not directly correlated with geological structures. Notwithstanding the impact of SSZ models in PSHA, the theoretical framework underlying SSZ models and the criteria used to delineate the SSZs are seldom explicitly stated and suitably docu- mented. In this paper, we propose a methodological framework to develop and docu- ment SSZ models, which includes (1) an assessment of the appropriate scale and degree of stationarity, (2) an assessment of seismicity catalog completeness-related issues, and (3) an evaluation and credibility ranking of physical criteria used to delin- eate the boundaries of the SSZs. We also emphasize the need for SSZ models to be supported by a comprehensive set of metadata documenting both the unique character- istics of each SSZ and the criteria used to delineate its boundaries. This procedure ensures that the uncertainties in the model can be properly addressed in the PSHA and that the model can be easily updated whenever new data are available. The pro- posed methodology is illustrated using the SSZ model developed for the Azores–West Iberian region in the context of the Seismic Hazard Harmonization in Europe project (project SHARE) and some of the most relevant SSZs are discussed in detail

    Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS

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    The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured

    Standalone vertex finding in the ATLAS muon spectrometer

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    A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

    Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

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    Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

    Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

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    The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal
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