12,093 research outputs found

    Estimations for the Single Diffractive production of the Higgs boson at the Tevatron and the LHC

    Full text link
    The single diffractive production of the standard model Higgs boson is computed using the diffractive factorization formalism, taking into account a parametrization for the Pomeron structure function provided by the H1 Collaboration. We compute the cross sections at next-to-leading order accuracy for the gluon fusion process, which includes QCD and electroweak corrections. The gap survival probability () is also introduced to account for the rescattering corrections due to spectator particles present in the interaction, and to this end we compare two different models for the survival factor. The diffractive ratios are predicted for proton-proton collisions at the Tevatron and the LHC for the Higgs boson mass of MHM_H = 120 GeV. Therefore, our results provide updated estimations for the diffractive ratios of the single diffractive production of the Higgs boson in the Tevatron and LHC kinematical regimes.Comment: 20 pages, 6 figures, 3 table

    Darth Fader: Using wavelets to obtain accurate redshifts of spectra at very low signal-to-noise

    Get PDF
    We present the DARTH FADER algorithm, a new wavelet-based method for estimating redshifts of galaxy spectra in spectral surveys that is particularly adept in the very low SNR regime. We use a standard cross-correlation method to estimate the redshifts of galaxies, using a template set built using a PCA analysis on a set of simulated, noise-free spectra. Darth Fader employs wavelet filtering to both estimate the continuum & to extract prominent line features in each galaxy spectrum. A simple selection criterion based on the number of features present in the spectrum is then used to clean the catalogue: galaxies with fewer than six total features are removed as we are unlikely to obtain a reliable redshift estimate. Applying our wavelet-based cleaning algorithm to a simulated testing set, we successfully build a clean catalogue including extremely low signal-to-noise data (SNR=2.0), for which we are able to obtain a 5.1% catastrophic failure rate in the redshift estimates (compared with 34.5% prior to cleaning). We also show that for a catalogue with uniformly mixed SNRs between 1.0 & 20.0, with realistic pixel-dependent noise, it is possible to obtain redshifts with a catastrophic failure rate of 3.3% after cleaning (as compared to 22.7% before cleaning). Whilst we do not test this algorithm exhaustively on real data, we present a proof of concept of the applicability of this method to real data, showing that the wavelet filtering techniques perform well when applied to some typical spectra from the SDSS archive. The Darth Fader algorithm provides a robust method for extracting spectral features from very noisy spectra. The resulting clean catalogue gives an extremely low rate of catastrophic failures, even when the spectra have a very low SNR. For very large sky surveys, this technique may offer a significant boost in the number of faint galaxies with accurately determined redshifts.Comment: 22 pages, 15 figures. Accepted for publication in Astronomy & Astrophysic

    The new automated daily mortality surveillance system

    Get PDF
    The experience reported in an earlier Eurosurveillance issue on a fast method to evaluate the impact of the 2003 heatwave on mortality in Portugal, generated a daily mortality surveillance system (VDM) that has been operating ever since jointly with the Portuguese Heat Health Watch Warning System. This work describes the VDM system and how it evolved to become an automated system operating year-round, and shows briefly its potential using mortality data from January 2006 to June 2009 collected by the system itself. The new system has important advantages such as: rapid information acquisition, completeness (the entire population is included), lightness (very little information is exchanged, date of death, age, sex, place of death registration). It allows rapid detection of impacts (within five days) and allows a quick preliminary quantification of impacts that usually took several years to be done. These characteristics make this system a powerful tool for public health action. The VDM system also represents an example of inter-institutional cooperation, bringing together organisations from two different ministries, Health and Justice, aiming at improving knowledge about the mortality in the population

    GORLIN-GOLTZ SYNDROME: A CASE REPORT

    Get PDF
    Introdução: O Síndrome de Gorlin-Goltz é uma condição hereditária autossómica dominante rara caracterizada por: carcinomas basocelulares, queratoquistos odontogénicos, depressões palmo-plantares, calcificações da foice cerebral e malformações esqueléticas. Associa-se também a meduloblastoma e outras neoplasias. Caso Clínico: Adolescente de 11 anos, com antecedentes de macrocefalia. Referenciada à consulta de estomatologia por quistos mandibulares recidivantes. O exame anátomo-patológico revelou tratarem-se de queratoquistos odontogénicos, pelo que é encaminhada para a consulta de pediatria. Objetivamente, apresentava macrocefalia e facies “gros seiro” com bossas frontais e hipertelorismo. Efetuou estudo genético, que detetou mutação do gene PTCH1, confirmando a suspeita clínica. Discussão: Os queratoquistos odontogénicos são o achado mais representativo do síndrome de Gorlin-Goltz nas duas primeiras décadas de vida, sendo de extrema importância um elevado índice de suspeição por parte do pediatra, com especial relevância para as alterações minor. Após o estabelecimento do diagnóstico, é necessária uma equipa multidisciplinar para um adequado seguimento e tratamento atempado.Introduction: The Gorlin-Goltz syndrome is a rare autosomal dominant inherited condition characterized by: basal cell carcinomas, odontogenic keratocysts, palmar or plantar pits, calcification of the falx cerebri and skeletal malformations. Medulloblastoma and other tumors are also associated with it. Case report: An 11-year-old female, with a history of macrocephaly, was referred to the Stomatology Department for recurrent mandibular cyst. Histopathological exam revealed odontogenic keratocysts, so the patient was referred to the Pediatric Department. Physical examination revealed macrocephaly and coarse face, with frontal bossing and hy pertelorism. The genetic study performed detected a mutation in PTCH1 gene, confirming the clinical suspicion. Discussion: Odontogenic keratocysts are the most representative finding in Gorlin-Goltz Syndrome in the first two decades of life, therefore a high suspicion level is mandatory among pediatricians concerning detection of minor changes. After the diagnosis, a multidisciplinary team is required for adequate follow-up and timely treatment
    corecore