Laboratory model to evaluate the influence of stress and corrosion in the formation of non-carious cervical lesions

Objetivo: Idealizar e testar um modelo laboratorial para simulação da etiologia multifatorial de lesões cervicais não cariosas, que permita avaliar o desenvolvimento dessas lesões com níveis crescentes de complexidade, com ênfase na tensão e na corrosão, visando contribuir com o esclarecimento dos mecanismos que conduzem à sua formação. Métodos: Os corpos de prova foram construídos com incisivos bovinos cortados na forma de palitos com 18 × 3 × 3 mm, com um entalhe na região cervical da parede voltada para a polpa, a fi m de concentrar as tensões na superfície da junção cemento-esmalte quando engastados no extremo apical e carregados em dobramento no extremo incisal. Um grupo foi imerso em água destilada e outro em solução tampão de acetato pH 4,5 durante 72 h. Cada grupo foi dividido em três subgrupos: sem carga e com carga (800 gf) para provocar tração ou para provocar compressão. Após o ensaio, os espécimes foram processados para histologia em lamelas de 0,05 mm, fotografados em microscópio de luz, e os danos foram avaliados. Conclusão: O modelo laboratorial desenvolvido permite a medida precisa da profundidade de perda e desmineralização de tecido dentário de corpos de prova submetidos ou não à tensão, bem como observar a ocorrência de outros danos como trincas e fraturas, o que torna possível inferir a influência da tensão de tração e compressão na etiologia das lesões cervicais não cariosas. O modelo poderá ser futuramente enriquecido com a possibilidade de aplicação cíclica de cargas e desafi os abrasivos intercalados.Objective: To conceive and test a laboratory model that simulates the multifactorial etiology of non-carious cervical lesions. The model enables researchers to assess the pathological process with increasing levels of complexity, focusing on tension and corrosion. The model is aimed at clarifying the mechanisms that lead to the development of these lesions. Methods: Specimens were manufactured from bovine incisors cut into 18 × 3 × 3 mm sticks, with a notch in the cervical region facing the pulp, in order to concentrate the stresses on the surface of the cementum-enamel junction when fi xed at the apical end and loaded for bending on the incisal edge. One group was immersed in distilled water and the other in pH 4.5 acetate buffer for 72 h. Each group was divided into three subgroups: one subgroup without loading, and two subgroups submitted to loading (800 gf) to cause either compression or tensile stress. After the test, 0.05 mm histological lamellae of the specimens were processed and photographed using a light microscope, and the damages were assessed. Conclusion: The laboratory model that was developed enabled the precise measurement of the depth of loss and demineralization of tooth tissue in the specimens, whether submitted to stress or not. The formation of other damages, such as cracks and fractures, could also be observed; this made it possible to infer the infl uence of compressive and tensile stresses on the etiology of non-carious cervical lesions. The model can be further enhanced by making it possible to apply cyclic loads and interspersed abrasive challenges

Isolamento de Candida spp. de estomatite relacionada à prótese no Pará, Brasil.

The aim of this study was to isolate and identify Candida species from the oral cavity of den-ture wearers with denture-related stomatitis who were attended at the University Federalof Pará (Belém City, Pará State, Brazil). A total of 36 denture wearers with denture-relatedstomatitis were included, and type I (50%), type II (33%) and type III (17%) stomatitis wereobserved. Candida spp. were isolated from 89% of the cases and included five differentCandida species. C. albicans was the most frequently recovered species (78% of the cases),followed by C. famata and C. tropicalis. We observed a significant association between Candidaspecies isolation and unsatisfactory denture condition (p = 0.0017). Our results demonstratedthe highly frequency of Candida species isolation in denture wearers with denture-relatedstomatitis and showed the relationship between these species and poor denture maintence.O objetivo deste estudo foi isolar e identificar espécies de Candida da cavidade oral de usuários com estomatite relacionada à dentadura, atendidos na Universidade Federal do Pará (Cidade de Belém, Pará, Brasil). Foram incluídos 36 usuários de protese com estomatite relacionada à prótese, e foram observadas estomatite tipo I (50%), tipo II (33%) e tipo III (17%). Candida spp. foram isolados em 89% dos casos e incluíram cinco espécies diferentes de Candida. C. albicans, frequentemente recuperada (78% dos casos), seguida por C. famata e C. tropicalis. Observamos uma associação significativa entre o isolamento da espécie Candidas e a condição insatisfatória da prótese (p = 0,0017). Nossos resultados demonstraram a alta frequência de isolamento de espécies de Candida em usuários de próteses com estomatite relacionada à prótese e mostraram a relação entre essas espécies e má manutenção da prótese

Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal

Standalone vertex finding in the ATLAS muon spectrometer

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

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

Measurement of the top quark pair cross section with ATLAS in pp collisions at √s=7 TeV using final states with an electron or a muon and a hadronically decaying τ lepton

A measurement of the cross section of top quark pair production in proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 7 TeV is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb -1. Events with an isolated electron or muon and a τ lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b quark. The measured cross section, σtt-=186±13(stat.)±20(syst.)±7(lumi.) pb, is in good agreement with the Standard Model prediction

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio

Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter

Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters