Browsing by Author "Santos, R."
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- Angular distributions in t(t)over-barH(H -> b(b)over-bar) reconstructed events at the LHCPublication . Santos, S. P. Amor dos; Araque, J. P.; Cantrill, R.; Castro, N. F.; Fiolhais, M. C. N.; Frederix, R.; Gonçalo, R.; Martins, R.; Santos, R.; Silva, J.; Onofre, A.; Peixoto, H.; Reigoto, A.The associated production of a Higgs boson and a top-quark pair, t (t) over barH, in proton-proton collisions is addressed in this paper for a center of mass energy of 13 TeV at the LHC. Dileptonic final states of t (t) over barH events with two oppositely charged leptons and four jets from the decays t -> bW(+) -> bl(+)v(l), (t) over bar -> (b) over barW(-) -> (b) over barl(-)(v) over bar (l) and h -> b (b) over bar are used. Signal events, generated with MadGraph5_aMC@NLO, are fully reconstructed by applying a kinematic fit. New angular distributions of the decay products as well as angular asymmetries are explored in order to improve discrimination of t (t) over barH signal events over the dominant irreducible background contribution, t (t) over barb (b) over bar. Even after the full kinematic fit reconstruction of the events, the proposed angular distributions and asymmetries are still quite different in the t (t) over barH signal and the dominant background (t (t) over barb (b) over bar).
- Experimental signatures of fermiophobic Higgs bosonsPublication . Brucher, L.; Santos, R.The most general Two Higgs Doublet Model potential without explicit CP violation depends on 10 real independent parameters. Excluding spontaneous CP violation results in two 7 parameter models. Although both models give rise to 5 scalar particles and 2 mixing angles, the resulting phenomenology of the scalar sectors is different. If flavour changing neutral currents at tree level are to be avoided, one has, in both cases, four alternative ways of introducing the fermion couplings. In one of these models the mixing angle of the CP even sector can be chosen in such a way that the fermion couplings to the lightest scalar Higgs boson vanishes. At the same time it is possible to suppress the fermion couplings to the charged and pseudo-scalar Higgs bosons by appropriately choosing the mixing angle of the CP odd sector. We investigate the phenomenology of both models in the fermiophobic limit and present the different branching ratios for the decays of the scalar particles. We use the present experimental results from the LEP collider to constrain the models.
- GASMoC method: a phenol-free technique to detect acid-fast bacilliPublication . Gomes, A.; Amaral, P.; Santos, R.; Santos, S.; Tortosa, F.; Mendonça, Paula; Marques-Ramos, AnaThe genre Mycobacterium includes a series of pathological species, such as M. tuberculosis, which is important for pathology laboratories to detect for a correct diagnosis. The Ziehl-Neelsen technique (ZNT) is the most common histochemical method used to detect these bacilli and uses a heated mixture of carbol-fuchsine, which contains basic fuchsine and phenol. Whereas the former component is responsible for the pinkish staining of acid-fast mycobacteria, the role of phenol is not completely understood and it has been suggested that its exclusion does not impact the detection ability of the ZNT. Since phenol is highly toxic and induces several injuries, the goal of this study is to determine the detection capacity of mycobacteria through a method that excludes the use of phenol. Accordingly, the GASMoC method, a modified ZNT that employs a solution of aqueous basic fuchsine heated at 37 °C, was tested on histological samples positive for mycobacteria and the results were compared to that of the ZNT. Data demonstrated that the GASMoC method was able to detect acid-fast bacilli (AFB) in all analyzed cases. Remarkably, microscopic inspection of mycobacteria was easier when the GASMoC method was applied. In conclusion, our study demonstrates that AFB detection does not require phenol and that the GASMoC method, a phenol-free technique, may substitute the ZNT in pathology laboratories.
- Health sciences schools students’ knowledge about human papillomavirus (HPV)Publication . Mendonça, Paula; Abreu, Renato; Ferreira, I.; Lopes, J.; Santos, R.Introduction - According to the World Health Organization (WHO), human papillomavirus (HPV) is the most frequent viral infection of the reproductive tract, with a high prevalence in the class of young people under 25 years, who doesn’t reveal much knowledge about it. For so, it’s fundamental to collect new data about it with an exploratory study. Objectives - To describe the knowledge of students in health technology courses, using surveys technique with REDCap application monitoring.
- Impact of flavor-changing neutral current top quark interactions on BR(t -> bW)Publication . Ferreira, P. M.; Santos, R.We study the effect that flavor-changing neutral current interactions of the top quark will have on the branching ratio of charged decays of the top quark. We have performed an integrated analysis using Tevatron and B-factories data and with just the further assumption that the Cabibbo-Kobayashi-Maskawa matrix is unitary, we can obtain very restrictive bounds on the strong and electroweak flavor-changing neutral current branching ratios Br(t -> qX)< 4.0x10(-4), where X is any vector boson and a sum in q=u, c is implied.
- Impacto do uso de fucsina básica aquosa na detecção de bacilos álcool-ácido resistentesPublication . Gomes, A.; Amaral, P.; Santos, R.; Santos, S.; Tortosa, F.; Mendonça, Paula; Marques-Ramos, AnaTuberculose - Infeção com maior mortalidade a nível mundial em 2016, causada pelo bacilo de Kock ou Mycobacterium tuberculosis. Técnica de Ziehl-Neelsen (ZN) - Evidenciar bacilos álcool-ácido resistentes (BAAR). Carbol-fucsina - Solução composta por fenol e fucsina básica. Objetivo geral do estudo - Determinar a capacidade de deteção da técnica de Ziehl-Neelsen sem o uso de fenol. Hipótese investigacional - Tendo por base dois estudos já realizados, é possível suprimir o fenol na técnica de ZN, através do uso de fucsina básica aquosa, sem afetar a capacidade de deteção de BAAR.
- Método GASMoC: uma técnica para detetar bacilos álcool ácido-resistentes sem fenolPublication . Gomes, A.; Amaral, P.; Santos, R.; Santos, S.; Tortosa, F.; Mendonça, Paula; Marques-Ramos, AnaA técnica de Ziehl-Neelsen (ZN) permite detetar bacilos álcoolácido resistentes (BAAR), tal como Mycobacterium tuberculosis (agente causador da tuberculose). Nesta técnica, a carbol-fucsina (CF) penetra a parede das BAAR conferindo-lhes uma tonalidade rosa que é mantida quando utilizada uma solução descorante, devido ao envelope celular que lhes confere resistência álcool-ácida2. Assim, as BAAR são demonstradas a rosa sobre um fundo azul. A CF implica o uso de fenol que liberta vapores, cuja inalação pode resultar em graves efeitos para a sua saúde a curto e a longo prazo. Alguns autores comprovaram a capacidade da fucsina básica aquosa (FBA) aquecida, como alternativa, para corar BAAR. Assim sendo, pretende-se com o presente estudo determinar a capacidade de deteção da técnica de Ziehl-Neelsen sem o uso de fenol.
- Stability of the tree-level vacuum in two Higgs doublet models against charge or CP spontaneous violationPublication . Ferreira, P. M.; Santos, R.; Barroso, A.We show that in two Higgs doublet models at tree-level the potential minimum preserving electric charge and CP symmetries, when it exists, is the global one. Furthermore, we derived a very simple condition, involving only the coefficients of the quartic terms of the potential, that guarantees spontaneous CP breaking. (C) 2004 Elsevier B.V. All rights reserved.