The inversion of the spatial lag operator in binary choice models : fast computation and a closed formula approximation

This paper presents a new method to approximate the inverse of the spatial lag operator matrix, used in the estimation of a spatial lag model with a binary dependent variable. The method is based on an approximation of the high order terms of the inverse series expansion. The proposed method is also applied to approximate other complex matrix operations and closed formulas for the elements of the approximated matrices are deduced. The approximated matrices are used in the gradients of a variant of Klier and McMillen's full GMM estimator, allowing to reduce the overall computational complexity of the estimation procedure. Monte Carlo experiments show that the new estimator performs well in terms of bias and root mean square error and exhibits a minimum trade-off between time and unbiasedness within a class of spatial GMM estimators. The new estimator is also applied to the analysis of competitiveness in the Metropolitan Statistical Areas of the United States of America. A new de_nition of binary competitiveness is proposed. Estimation of the spatial dependence parameter and the environmental effects are addressed as central issues.info:eu-repo/semantics/publishedVersio

The inversion of the spatial lag operator in binary choice models: Fast computation and a closed formula approximation

This paper presents a new method to approximate the inverse of the spatial lag operator, used in the estimation of spatial lag models for binary dependent variables. The related matrix operations are approximated as well. Closed formulas for the elements of the approximated matrices are deduced. A GMM estimator is also presented. This estimator is a variant of Klier and McMillen’s iterative GMM estimator. The approximated matrices are used in the gradients of the new iterative GMM procedure. Monte Carlo experiments suggest that the proposed approximation is accurate and allows to significantly reduce the computational complexity, and consequently the computational time, associated with the estimation of spatial binary choice models, especially for the case where the spatial weighting matrix is large and dense. Also, the simulation experiments suggest that the proposed iterative GMM estimator performs well in terms of bias and root mean square error and exhibits a minimum trade-off between computational time and unbiasedness within a class of spatial GMM estimators. Finally, the new iterative GMM estimator is applied to the analysis of competitiveness in the U.S. Metropolitan Statistical Areas. A new definition for binary competitiveness is introduced. The estimation of spatial and environmental effects are addressed as central issues.info:eu-repo/semantics/publishedVersio

COVID-19 risk perception and confidence among clinical dental students: impact on patient management

Communication abstract: Proceedings of the 5th International Congress of CiiEM - Reducing inequalities in Health and Society, held at Egas Moniz’ University Campus in Monte de Caparica, Almada, from June 16th to 18th, 2021.This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This study aimed to assess COVID-19 perceived risk, confidence and its impact on potentially infected patients’ management practices, in a clinical dental education setting. The survey was conducted by application of a self-administered questionnaire amid the COVID-19 pandemic. Results indicate high COVID-19 perceived risk and confidence levels (86.7% and 72.8%, respectively). A significantly lower risk perception was identified for individuals classifying COVID-19 as a moderately dangerous disease and confidence was significantly lower for women and for individuals not previously exposed to confirmed or suspected cases of COVID-19. No factor-related significant differences were found on potentially infected patients’ management practices.info:eu-repo/semantics/publishedVersio

Changes in oral microflora in prosthetic patients on hygiene protocol

Poster presented at the 1st International Congress of CiiEM - From Basic Sciences to Clinical Research, 27-28 November 2015, Egas Moniz, Caparica, Portugal

The Role of Herbal Medicine in the Treatment of Acne Vulgaris: A Systematic Review of Clinical Trials

Over the past few decades, interest in medicinal plants and phytochemicals for the treatment of skin disorders, including acne vulgaris, has progressively increased. Acne vulgaris is a chronic inflammatory disease of the pilosebaceous unit, which mainly occurs in adolescents and young adults. The treatment focuses on the four main factors involved in its pathogenesis: increased sebum production, hyperkeratinization, overgrowth of Cutibacterium acnes, and inflammation. The treatment includes topical retinoids, benzoyl peroxide, antibiotics, and oral isotretinoin. In this regard, the use of herbal medicine as a complementary and alternative medicine is a promising strategy. The main objective of this study was to systematically evaluate the efficacy and safety of medicinal plants and phytochemicals in the treatment of acne vulgaris. Three scientific databases (PubMed, Web of Science, and Scopus) were searched from inception to January 2021. Clinical trials comparing herbal therapies with placebo or other medicines for the treatment of acne vulgaris were included and analyzed. Outcome measures of interest comprised acne lesions (inflammatory and noninflammatory), sebum production, acne severity, and quality of life. The risk of bias in the included randomized controlled trials (RCTs) was assessed using the Cochrane risk-of-bias tool. A total of 34 clinical trials involving 1753 participants met the inclusion criteria for this systematic review. Most trials showed that herbal medicine significantly reduces inflammatory and noninflammatory acne lesions and has a relevant effect on acne severity. Some medicinal plants revealed equal or higher efficacy to standard treatments. No significant difference between groups in sebum production and quality of life was observed and no severe adverse events were reported. This systematic review provides evidence that medicinal plants and phytochemicals are promising treatments for mild to moderate acne vulgaris. However, more quality of evidence and standardized methodologies are needed to support their effectiveness and safety claims.info:eu-repo/semantics/publishedVersio

Estudo da associação entre a literacia para a saúde e a atividade física em alunos de duas instituições portuguesas do ensino superior

RESUMO - Introdução: A atividade física é de importância reconhecida na promoção da saúde. Sabe-se também que níveis de literacia para a saúde desadequados compromete a adesão, não só a comportamentos promotores da saúde, como também à prevenção da doença, estando associados a piores indicadores de saúde. Não se conhecendo bem a associação entre a literacia para a saúde e a atividade física, em particular e especialmente em estudantes do ensino superior, este estudo teve como objetivo estudar essa associação em alunos de duas instituições de ensino superior, uma pré-graduada e outra pós-graduada. Metodologia: Realizou-se um estudo observacional, transversal, numa amostra de alunos do IPVC e da ENSP, recolhendo-se informação através de um inquérito composto por questões socioeconómicas, demográficas e clínicas e por dois questionários, o HLS-EU, e o IPAQ – Questionário Internacional de Atividade Física. Os dados foram recolhidos em 2017 e em 2019. A associação entre a literacia para a saúde e a atividade física foi estimada recorrendo-se a modelos de regressão logística binária. Resultados: Participaram no estudo 314 alunos, 55,1% do sexo feminino, com idade mediana de 20 anos (amplitude interquartil de 9 anos), 68,8% eram do IPVC. No score global de Literacia para a Saúde, 45,4% dos estudantes apresentaram um nível inadequado ou problemático e, na Atividade Física, 65,6% dos estudantes eram sedentários ou apenas moderadamente ativos, não existindo diferenças estatisticamente significativas entre as duas instituições do ensino superior. O subíndice da Literacia para a Saúde que mais se associou à probabilidade de ser ativo foi o da Promoção da Saúde (ORajustado = 5,50; IC95%: 2,01 – 14,0). Discussão/Conclusão: Encontramos associação estatisticamente significativa entre maior nível de literacia para a saúde e maior probabilidade de ser ativo nestes jovens estudantes do ensino superior. Este estudo alerta-nos também para a elevada proporção de jovens sedentários ou moderadamente ativos, assim como com nível inadequado ou problemático de literacia para a saúde, o que permite salientar as evidentes oportunidades de intervenção, quer na literacia para a saúde, nomeadamente na Promoção da Saúde, quer também na prática de atividade física

Dentists and undergraduate dental students require more information relating to child abuse

This is an open access article distributed under the terms of the creative commons attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution,and reproduction in any medium, provided the original work is properly cited.OBJECTIVE: To evaluate the preparation for, and the appropriate approach of dentists to the diagnosis of patient mistreatment. METHOD: This investigation was conducted among sixty randomly selected dentistry students: twenty 1st year students, ten 5th year students at our institution, ten 5th year students at the Faculty of Dentistry, Lisbon University, sixteen dentists at the University Clinic of our institution, and four dentists with private offices. Students and dentists took part voluntarily. The exclusion criteria were (a) prior attendance of another degree, (b) cooperation with social organizations; and, for professionals, less than five years of experience. Data analysis was performed through descriptive and inferential statistics (chi-squared test) for a confidence level of 95%. RESULTS: Among dentists, 38% do not know which area of the organism is the most affected, 43% know it is proper to officially report the fact; out of these, 48% know that the information may be provided anonymously. There are 47% who state that they received no undergraduate training in this area. However, 60% of the students in the last year declare they did receive training. CONCLUSIONS: Dentists are not sufficiently familiar with the subject of child abuse. A regular approach to this matter in undergraduate education is important. It will be very useful to create a working tool unifying the criteria for screening, diagnosing, and registering such events

Prevalence of the golden proportion on dental students

Poster presented at the 2014 IADR/PER Congress (International Association for Dental Research). Dubrovnik, Croatia, September 10-13, 201

JaSkel: a java skeleton-based framework for structured cluster and grid computing

This paper presents JaSkel, a skeleton-based framework to develop parallel and grid applications. The framework provides a set of Java abstract classes as a skeleton catalogue, which implements recurring parallel interaction paradigms. This approach aims to improve code efficiency and portability. It also helps to structure scalable applications through the refinement and composition of skeletons. Evaluation results show that using the provided skeletons do contribute to improve both application development time and execution performanceFundação para a Ciência e a Tecnologia (FCT) - PPC-VM Project(POSI/CHS/47158/2002); Project SeARCH (contract REEQ/443/2001)

High fidelity walkthroughs in archaeology sites

Comunicação apresentada no 6th International Symposium on Virtual Reality, Archaeology and Cultural Heritage (VAST 2005), Pisa, Italy, 8-11 Novembro 2005.Fast and affordable computing systems currently support walkthroughs into virtual reconstructed sites, with fast frame rate generation of synthetic images. However, archaeologists still complain about the lack of realism in these interactive tours, mainly due to the false ambient illumination. Accurate visualizations require physically based global illumination models to render the scenes, which are computationally too demanding. Faster systems and novel rendering techniques are required: current clusters provide a feasible and affordable path towards these goals, and we developed a framework to support smooth virtual walkthroughs, using progressive rendering to converge to high fidelity images whenever computing power surplus is available. This framework exploits spatial and temporal coherence among successive frames, serving multiple clients that share and interact with the same virtual model, while maintaining each its own view of the model. It is based on a three-tier architecture: the outer layer embodies light-weight visualization clients, which perform all the user interactions and display the final images using the available graphics hardware; the inner layer is a parallel version of a physically based ray tracer running on a cluster of off-the-shelf PCs; in the middle layer lies the shading management agent (SMA), which monitors the clients' states, supplies each with properly shaded 3D points, maintains a cache of previously rendered geometry and requests relevant shading samples to the parallel renderer, whenever required. A prototype of a high fidelity walkthrough in the archaeologic virtual model of the roman town of Bracara Augusta was developed, and the current evaluation tests aimed to measure the performance improvements due to the use of SMA caches and associated parallel rendering capabilities. Preliminary results show that interactive frame rates are sustainable and the system is highly responsive.Fundação para a Ciência e Tecnologia (FCT) - POSI/CHS/42041/2001