12,026 research outputs found

    On the renormalization of the electroweak chiral Lagrangian with a Higgs

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    We consider the scalar sector of the effective non-linear electroweak Lagrangian with a light "Higgs" particle, up to four derivatives in the chiral expansion. The complete off-shell renormalization procedure is implemented, including one loop corrections stemming from the leading two-derivative terms, for finite Higgs mass. This determines the complete set of independent chiral invariant scalar counterterms required for consistency; these include bosonic operators often disregarded. Furthermore, new counterterms involving the Higgs particle which are apparently chiral non-invariant are identified in the perturbative analysis. A novel general parametrization of the pseudoescalar field redefinitions is proposed, which reduces to the various usual ones for specific values of its parameter; the non-local field redefinitions reabsorbing all chiral non-invariant counterterms are then explicitly determined. The physical results translate into renormalization group equations which may be useful when comparing future Higgs data at different energies

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

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    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

    GORLIN-GOLTZ SYNDROME: A CASE REPORT

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    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

    Abelhas nativas sem ferrão (Meliponini) e serviços de polinização em espécies florestais.

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    Capacity of a traditional timber mortise and tenon joint

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    The safety and quality of traditional timber structures mostly depends on the conditions of their connections. A testing campaign has investigated the behaviour of mortise and tenon timber joint. The present paper addresses the quantification of the strength capacity of wood-wood mortise and tenon joint by physical testing of full-scale specimens. In addition, the performance of different non-destructive techniques (NDT) for assessing global strength is also evaluated. For this three non-destructive methods (ultrasonic testing, Resistograph and Pilodyn) are considered and the possibility of their application is discussed based on the application of simple linear regression models. New (NCW) and old (OCW) chestnut wood, obtained from structural elements belonging to old buildings, is used. Finally, a nonlinear model has been formulated and the predicted behaviour compared with the behaviour observed in the full-scale experiments, in terms of failure mode and the ultimate load. The study has shown very good agreement with the experimental values.(undefined
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