Estudo do decaimento B→D(KsKK)K∗B \to D(K_{s}KK)K^{*} no experimento LHCb

This thesis has two independent parts: a study of a B meson decay mode and a contribution to the assembly of the experiment. The analysis describes the LHCb sensitivity to the decay $B^0 \to D^{0}(K^{0}_{s}K^{+}K^{-}) K^{*}(892)^0$. This decay can be used to extract the γ phase of CKM matrix, for which there is no conclusive measurement until now. The experimental contribution had been realized in the muon system, through the tests of the MWPC chambers, that will be installed at this system

On the κ\kappa-Dirac Oscillator revisited

This Letter is based on the $\kappa$-Dirac equation, derived from the $\kappa$-Poincar\'{e}-Hopf algebra. It is shown that the $\kappa$-Dirac equation preserves parity while breaks charge conjugation and time reversal symmetries. Introducing the Dirac oscillator prescription, $\mathbf{p}\to\mathbf{p}-im\omega\beta\mathbf{r}$, in the $\kappa$-Dirac equation, one obtains the $\kappa$-Dirac oscillator. Using a decomposition in terms of spin angular functions, one achieves the deformed radial equations, with the associated deformed energy eigenvalues and eigenfunctions. The deformation parameter breaks the infinite degeneracy of the Dirac oscillator. In the case where $\varepsilon=0$, one recovers the energy eigenvalues and eigenfunctions of the Dirac oscillator.Comment: 5 pages, no figures, accepted for publication in Physics Letters

Interference suppression with physical-layer network coding and MIMO for multi-way channels

Orthogonal techniques (such as TDMA – time division multiple access) are traditionally used when a set of terminals wants to exchange data and a relay is required when wireless terminals cannot communicate directly. This paper proposes two schemes to address multi-way channels when a set of terminals wants to exchange data. Both proposed schemes consist of a first phase based on virtual MIMO with lattice reduction-aided (LRA) detection at the relay, establishing a multiple access channel (MAC). Two new strategies are then proposed for the second (multicast) phase; one for single antenna terminals and another for multiple-input multiple-output (MIMO) terminals. The second strategy achieves interference suppression by successively combining physical layer network coding and MIMO detection (with LRA detectors also at the terminals). The paper assesses a 3 terminals network with a relay for which a TDMA-based scheme would require 6 time-slots, while the proposed strategy for MIMO terminals is able to exchange the information between all terminals using 2 time-slots only. This latter scheme is easily scalable to a higher number of terminals, and always able to accomplish the exchange of messages between all of them in just 2 time-slots, although limited by the number of antennas that the terminals can fit and also the MIMO processing complexity they can afford.info:eu-repo/semantics/acceptedVersio

A Multiple Criteria Framework to Evaluate Bank Branch Potential Attractiveness

Remarkable progress has occurred over the years in the performance evaluation of bank branches. Even though financial measures are usually considered the most important in assessing branch viability, we posit that insufficient attention has been given to other factors that affect the branches’ potential profitability and attractiveness. Based on the integrated used of cognitive maps and MCDA techniques, we propose a framework that adds value to the way that potential attractiveness criteria to assess bank branches are selected and to the way that the trade-offs between those criteria are obtained. This framework is the result of a process involving several directors from the five largest banks operating in Portugal, and follows a constructivist approach. Our findings suggest that the use of cognitive maps systematically identifies previously omitted criteria that may assess potential attractiveness. The use of MCDA techniques may clarify and add transparency to the way trade-offs are dealt with. Advantages and disadvantages of the proposed framework are also discussed.

Thromboprophylaxis With Apixaban in Patients Undergoing Major Orthopedic Surgery: Meta-Analysis and Trial-Sequential Analysis

Background: Venous thromboembolism (VTE) is a potentially fatal complication of orthopedic surgery, and until recently, few antithrombotic compounds were available for postoperative thromboprophylaxis. The introduction of the non–vitamin K antagonists oral anticoagulants (NOAC), including apixaban, has extended the therapeutic armamentarium in this field. Therefore, estimation of NOAC net clinical benefit in comparison with the established treatment is needed to inform clinical decision making. Objectives: Systematic review to assess the efficacy and safety of apixaban 2.5 mg twice a day versus low-molecular-weight heparins (LMWH) for thromboprophylaxis in patients undergoing knee or hip replacement. Data sources: MEDLINE, Embase, and CENTRAL were searched from inception to September 2016, other systematic reviews, reference lists, and experts were consulted. Study eligibility criteria, participants, and intervention: All major orthopedic surgery randomized controlled trials comparing apixaban 2.5 mg twice daily with LMWH, reporting thrombotic and bleeding events. Data extraction: Two independent reviewers, using a predetermined form. Study appraisal and synthesis methods: The Cochrane tool to assess risk bias was used by two independent authors. RevMan software was used to estimate pooled risk ratio (RR) and 95% confidence intervals (95% CI) using random-effects meta-analysis. Trial sequential analysis (TSA) was performed in statistical significant results to evaluate whether cumulative sample size was powered for the obtained effect. Overall confidence in cumulative evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group methodology. Results: Four studies comparing apixaban 2.5 mg twice daily with LMWH were included, with a total of 11.828 patients (55% undergoing knee and 45% hip replacement). The overall risk of bias across studies was low. In comparison with LMWH (all regimens), apixaban showed a significantly lower risk of VTE events and overall mortality combined (RR: 0.63, 95% CI: 0.42-0.95, I2 = 84%, n = 8346), but not of major VTE events (RR: 0.62, 95% CI: 0.32-1.19, I2 = 63%, n = 9493), or of symptomatic VTE events and VTE-related mortality combined (RR: 1.14, 95% CI: 0.68-1.90, I2 = 0%, n = 11 879). Trial sequential analysis showed that the risk reduction obtained for VTE and mortality was based on underpowered cumulative sample size and effect dimension. Subgroup analysis according to LMWH regimens showed that apixaban reduced the risk of VTE events and overall mortality, and major VTE events, when compared with LMWH once daily, without differences between apixaban and LMWH twice daily. Conclusions: There is low to moderate evidence that in patients undergoing knee or hip replacement, apixaban seems equally effective and safe to LMWH twice a day. When compared with LMWH once a day, apixaban seems a superior thromboprophylaxis option. However, the results are underpowered which precludes definite answers regarding the true net clinical benefit of apixaban versus LMWH in this clinical context

Avaliação dos Resultados do Cross-Linking de Colagénio Corneano em Doentes com Queratocone: a Nossa Experiência

Objectivo: Avaliar os resultados visuais e queratométricos do tratamento com cross-linking de colagénio corneano (CXL) no queratocone progressivo realizado no Centro Hospitalar de Entre Douro e Vouga durante o período de 1 ano. Material e Métodos: Estudo retrospetivo no qual foram incluídos 15 olhos (15 doentes) com queratocone progressivo. Todos os pacientes foram submetidos ao tratamento com CXL com riboflavina e luz ultravioleta-A segundo o protocolo de Dresden. 8 olhos completaram 12 meses de seguimento e, 7 olhos completaram 6 meses. Avaliámos a acuidade visual com e sem correcção, cilindro refractivo e equivalente esférico, topografia corneana e paquimetria com Pentacam®, assim como os parâmetros obtidos com o Ocular Response Analyzer®. Resultados: Verificou-se uma melhoria da melhor acuidade visual corrigida média de 0.56 +/- 0.18 para 0.60 +/- 0.18 aos 3 meses, atingindo aos 6 meses 0.69, diferença estatisticamente significativa (p=0.007) e aos 12 meses 0.72 (p=0.003). Os valores do cilindro refractivo e equivalente esférico diminuíram após o procedimento mas sem significado estatístico. Em todos os olhos tratados verificou-se estabilização da progressão. A média da queratometria máxima diminui significativamente de 51.11D pré-operatório para 49.63D (p=0.002) aos 6 meses e para 50.0 D aos 12 meses (p=0.01). Conclusões: O CXL de colagénio é um tratamento promissor para o queratocone evolutivo pois permite atrasar a progressão da doença e, em alguns casos, melhorar os parâmetros visuais, refractivos e topográficos. Os nossos resultados mostram uma melhoria funcional e morfológica, com a estabilização da progressão da doença, sendo necessário, no entanto, resultados a longo prazo.info:eu-repo/semantics/publishedVersio

Variabilidade genética entre diploides de banana quanto ao despencamento dos frutos.

O despencamento natural dos frutos maduros é um dos graves problemas dos programas de melhoramento genético de bananeira relacionado a qualidade do fruto. O desprendimento individual dos frutos é uma desordem fisiológica associada ao amadurecimento (1), que resulta em alta perecibilidade pós-colheita