Mining Order-Preserving Submatrices from Data with Repeated Measurements

published_or_final_versio

A unified wavelet-based modelling framework for non-linear system identification: the WANARX model structure

A new unified modelling framework based on the superposition of additive submodels, functional components, and wavelet decompositions is proposed for non-linear system identification. A non-linear model, which is often represented using a multivariate non-linear function, is initially decomposed into a number of functional components via the wellknown analysis of variance (ANOVA) expression, which can be viewed as a special form of the NARX (non-linear autoregressive with exogenous inputs) model for representing dynamic input–output systems. By expanding each functional component using wavelet decompositions including the regular lattice frame decomposition, wavelet series and multiresolution wavelet decompositions, the multivariate non-linear model can then be converted into a linear-in-theparameters problem, which can be solved using least-squares type methods. An efficient model structure determination approach based upon a forward orthogonal least squares (OLS) algorithm, which involves a stepwise orthogonalization of the regressors and a forward selection of the relevant model terms based on the error reduction ratio (ERR), is employed to solve the linear-in-the-parameters problem in the present study. The new modelling structure is referred to as a wavelet-based ANOVA decomposition of the NARX model or simply WANARX model, and can be applied to represent high-order and high dimensional non-linear systems

Mecanização agrícola - Transmissões mecânicas em máquinas agrícolas

Este trabalho destina-se a apoiar a aprendizagem de estudantes do ramo das ciências agrárias sobre aspectos relevantes das transmissões mecânicas nas máquinas agrícolas. A transmissão mecânica, formada normalmente por uma cadeia de componentes, constitui um dos modos possíveis para efectuar a transmissão de potência desde uma fonte (exemplo: a tomada-de-força do tractor) para diversos órgãos dos equipamentos agrícolas. São apresentadas as diferentes soluções de transmissão mecânica presentes nos equipamentos agrícolas, com a preocupação focada nos aspectos de manutenção, regulações permitidas e protecção do operador. O texto não está vocacionado para aspectos de dimensionamento de transmissões; contudo, faz-se a apresentação dos princípios de cinemática e dinâmica das transmissões que constitui a ferramenta necessária para se entenderem as transmissões susceptíveis de regulação por parte do operador. Será dada especial ênfase às transmissões mecânicas passíveis de regulação de semeadores de linhas e de plantadores, para efeitos de regulação da densidade de sementeira/plantação/adubação. São apresentados problemas de aplicação. Este trabalho reúne textos de anteriores edições do mesmo autor: Transmissões mecânicas (2012, 2007, 2004, 2002, 1998; 1994; 1990; 1988; 1986); Transmissões mecânicas – Equipamentos agrícolas com regulação da transmissão – Grade rotativa (2008); Transmissões mecânicas – Equipamentos agrícolas com regulação da transmissão – Semeadores de linhas monogrão e plantadores (2012, 2008); Transmissões mecânicas – Equipamentos agrícolas com regulação da transmissão – Semeadores de linhas de fluxo contínuo (2011, 2009); Transmissões mecânicas – Equipamentos agrícolas com regulação da transmissão – Semeadores de linhas, de fluxo contínuo, com transporte de sementes em corrente de ar (2012, 2008). Os textos acima indicados foram publicados periodicamente no contexto de disciplinas em cursos da Universidade de Évora, nomeadamente: - Mecânica Aplicada (1983/84 a 2003/04) - disciplina obrigatória do 3º semestre os cursos de Engenharia Agrícola e Engenharia Zootécnica; - Fundamentos de Engenharia nas Máquinas Agrícolas – (2004/05 e 2005/06) – disciplina obrigatória do 3º semestre de Engenharia Agrícola; - Tecnologia dos Equipamentos Agrícolas – (2004/05 e 2005/06) – disciplina obrigatória do 3º semestre de Engenharia Zootécnica; - Mecanização Agrícola (2006/07 até ao presente) – unidade curricular obrigatória do 3º semestre da licenciatura em Agronomia; - Princípios de Engenharia Aplicados à Ciência Animal (2006/07 até ao presente) – unidade curricular obrigatória do 1º ciclo em Ciência e Tecnologia Animal

Modelos de sobrevivência para o estudo dos fatores de prognóstico até à ocorrência da resposta ao tratamento de fisioterapia em utentes com dor lombar crónica

Relatório do Projeto de Investigação apresentado para cumprimento dos requisitos necessários à obtenção do grau de Mestre em Fisioterapia, área de especialização em Fisioterapia em Condições Músculo-EsqueléticasIntrodução: A recuperação, da função e/ou dor, é comummente utilizada em estudos relacionados com a dor lombar crónica não específica (DLCNE), contudo, os desenhos utilizados para medir a resposta ao tratamento não permitem saber quando, no decorrer da intervenção, é atingido um determinado critério de resposta ao tratamento, e consequentemente quais os fatores que aumentam o risco/ a probabilidade de obter esse critério de resposta ao tratamento ao longo do tempo. Objetivo: Este estudo pretendeu identificar fatores de prognóstico que influenciem significativamente o tempo até à ocorrência de um evento de interesse, definido como resposta ao tratamento multimodal de fisioterapia na intensidade da dor, incapacidade funcional e perceção de melhoria em indivíduos com DCLNE, recorrendo a avaliações repetidas semanalmente, durante 8 semanas. Metodologia: Estudo observacional de coorte prospetivo com 135 indivíduos com DLCNE referenciados para a fisioterapia, que foram avaliados no início da intervenção de fisioterapia e semanalmente desde a segunda até à oitava semana de intervenção. O “evento” definido foi a obtenção do critério de sucesso na resposta ao tratamento, estabelecido para cada outcome com base no valor da respetiva DCMI, definida como a diminuição ≥ 30% na escala numérica da dor (END) e na versão portuguesa da Quebec Back Pain Disability Scale (QBPDS-PT) e diferença mínima de 3 pontos para a versão portuguesa da Global Back Recovery Scale (GBRS-PT), mantidas durante um mínimo de 7 dias. Resultados: A proporção de utentes que alcançou a recuperação para a intensidade da dor e incapacidade funcional, no período de 8 semanas de tratamento, foi de 51.11% (n=69) e de 50.37% (n=68), respetivamente. A proporção de utentes que alcançou a recuperação na perceção de melhoria foi de 55.56% (n=75). A mediana do tempo de recuperação para os 3 outcomes ocorreu na 6ª semana de tratamento. Os indivíduos com maior intensidade de dor na baseline (HR:1.26, 95%IC: 1.12-1.43), que nunca ou raramente se sentiram “desamparados” (HR:2.09, 95%IC: 1.07-4.08), têm maior possibilidade de atingir o critério de recuperação para a dor, comparativamente aos utentes que não possuem estas características. Os indivíduos que vivem sozinhos (HR: 1.83, 95%IC: 1,05-3,19) têm maior possibilidade de atingir o critério de recuperação para a incapacidade funcional. Os utentes com inferior nível de ensino têm uma maior probabilidade de recuperação da perceção global de melhoria (IR:1.65; 95%IC: 1.02-2.67) comparativamente com utentes com mais formação. Conclusão: A recuperação da intensidade da dor e da incapacidade funcional ocorre nas primeiras 6 semanas de tratamento, sendo que aproximadamente metade dos utentes recuperados alcançaram o critério de resposta após as 2 primeiras semanas de tratamento. Maior intensidade da dor na baseline, baixos níveis de fatores psicossociais, viver sozinho e ter um nível educacional mais baixo, parece favorecer a probabilidade de recuperar destes utentes, ao longo do tempo.Introduction: The recovery from pain or function is usualy used in nonspecific chronic low back pain (NCLBP) studies. The designs to measure the response to treatment don’t allow to know when, whithin the intervention, the criteria of recovery is achieved and, therefore, which are the factors that increase the possibility of achieving the defined sucess along the time. Objective: The aim of this study is to identify prognosis factors that favour significantly the time until reaching the event of interest, defined as the response to the multimodal physiotherapy treatment for pain intensity, disability and global perception of recovery in patients with NCLBP, using repetitive assessments on a weekly basis for 8 weeks. Methodology: In this prospective cohort study were 135 NCLBP patients who were referred for physiotherapy and assessed 8 times (baseline and every week from 2nd to the 8th week) The event of interest was defined as the achievement of the recovery criteria on the treatment response, established for each outcome, considering the minimal important change (MIC) defined as a reduction of ≥ 30% on numeric rate scale (NRS) and portuguese version of Quebec Back Pain Disability Scale (QBPDS-PT) and a reduction of 3 points on the portuguese version of Global Back Recovery Scale (GBRS-PT), maintened for at least 7 days. Results: The proportion of patients that have acheived the recovery for pain intensity and disability, on the 8 weeks treatment was 51.11% (n=69) and 50.37% (n=68), respectivetly. The proportion of patiens that have acheived recovery for the global perception was 55.56% (n=75). The median of recovery time for the 3 outcomes occured on the 6th week. The NCLBP patients who have more pain intensity on baseline (HR: 1.26; 95%IC: 1.12-1.43) and who didn’t feel with support on the previous week (HR: 2.09; 95%IC: 1.07-4.08) have more possibility to achieve the recovery criteria for pain, compared with those that don’t have that caracteristics. The patients that live alone (HR: 1.83, 95%IC: 1,05-3,19) have more possibility of achieve the disability recovery, when compared with those who don´t. Patients with lower levels of education have more probability to recovery from global perception of recovery (IR:1.65; 95%IC: 1.02-2.67), compared with patients with higher levels of education. Conclusions: The recovery for pain intensity and disability occurs on the 6 first weeks of treatment, and approximetely half of the patients achieved the response criteria in the 2 first weeks. Higher levels of pain intensity on the baseline, lower levels for the psycosocial factors, living alone ad lower levels of education, seems to favour the probability or recovery on NCLBP patients, along the time

Influenza H5N1 virus infection of polarized human alveolar epithelial cells and lung microvascular endothelial cells

Background: Highly pathogenic avian influenza (HPAI) H5N1 virus is entrenched in poultry in Asia and Africa and continues to infect humans zoonotically causing acute respiratory disease syndrome and death. There is evidence that the virus may sometimes spread beyond respiratory tract to cause disseminated infection. The primary target cell for HPAI H5N1 virus in human lung is the alveolar epithelial cell. Alveolar epithelium and its adjacent lung microvascular endothelium form host barriers to the initiation of infection and dissemination of influenza H5N1 infection in humans. These are polarized cells and the polarity of influenza virus entry and egress as well as the secretion of cytokines and chemokines from the virus infected cells are likely to be central to the pathogenesis of human H5N1 disease.Aim: To study influenza A (H5N1) virus replication and host innate immune responses in polarized primary human alveolar epithelial cells and lung microvascular endothelial cells and its relevance to the pathogenesis of human H5N1 disease.Methods: We use an in vitro model of polarized primary human alveolar epithelial cells and lung microvascular endothelial cells grown in transwell culture inserts to compare infection with influenza A subtype H1N1 and H5N1 viruses via the apical or basolateral surfaces.Results: We demonstrate that both influenza H1N1 and H5N1 viruses efficiently infect alveolar epithelial cells from both apical and basolateral surface of the epithelium but release of newly formed virus is mainly from the apical side of the epithelium. In contrast, influenza H5N1 virus, but not H1N1 virus, efficiently infected polarized microvascular endothelial cells from both apical and basolateral aspects. This provides a mechanistic explanation for how H5N1 virus may infect the lung from systemic circulation. Epidemiological evidence has implicated ingestion of virus-contaminated foods as the source of infection in some instances and our data suggests that viremia, secondary to, for example, gastro-intestinal infection, can potentially lead to infection of the lung. HPAI H5N1 virus was a more potent inducer of cytokines (e.g. IP-10, RANTES, IL-6) in comparison to H1N1 virus in alveolar epithelial cells, and these virus-induced chemokines were secreted onto both the apical and basolateral aspects of the polarized alveolar epithelium.Conclusion: The predilection of viruses for different routes of entry and egress from the infected cell is important in understanding the pathogenesis of influenza H5N1 infection and may help unravel the pathogenesis of human H5N1 disease. © 2009 Chan et al; licensee BioMed Central Ltd.published_or_final_versio

The wavelet-NARMAX representation : a hybrid model structure combining polynomial models with multiresolution wavelet decompositions

A new hybrid model structure combing polynomial models with multiresolution wavelet decompositions is introduced for nonlinear system identification. Polynomial models play an important role in approximation theory, and have been extensively used in linear and nonlinear system identification. Wavelet decompositions, in which the basis functions have the property of localization in both time and frequency, outperform many other approximation schemes and offer a flexible solution for approximating arbitrary functions. Although wavelet representations can approximate even severe nonlinearities in a given signal very well, the advantage of these representations can be lost when wavelets are used to capture linear or low-order nonlinear behaviour in a signal. In order to sufficiently utilise the global property of polynomials and the local property of wavelet representations simultaneously, in this study polynomial models and wavelet decompositions are combined together in a parallel structure to represent nonlinear input-output systems. As a special form of the NARMAX model, this hybrid model structure will be referred to as the WAvelet-NARMAX model, or simply WANARMAX. Generally, such a WANARMAX representation for an input-output system might involve a large number of basis functions and therefore a great number of model terms. Experience reveals that only a small number of these model terms are significant to the system output. A new fast orthogonal least squares algorithm, called the matching pursuit orthogonal least squares (MPOLS) algorithm, is also introduced in this study to determine which terms should be included in the final model

Bayesian regression filter and the issue of priors

We propose a Bayesian framework for regression problems, which covers areas which are usually dealt with by function approximation. An online learning algorithm is derived which solves regression problems with a Kalman filter. Its solution always improves with increasing model complexity, without the risk of over-fitting. In the infinite dimension limit it approaches the true Bayesian posterior. The issues of prior selection and over-fitting are also discussed, showing that some of the commonly held beliefs are misleading. The practical implementation is summarised. Simulations using 13 popular publicly available data sets are used to demonstrate the method and highlight important issues concerning the choice of priors

Association between oral fluoroquinolones and seizures: A self-controlled case series study.

OBJECTIVES: The aim of this study was to investigate the association and to estimate the crude absolute risk of seizure among patients exposed to fluoroquinolones (FQs) in Hong Kong and the United Kingdom. METHODS: A self-controlled case series study was conducted. Data were collected from the Hong Kong Clinical Data Analysis and Reporting System database and the Clinical Practice Research Datalink. Patients who were prescribed any oral FQ and had an incident seizure diagnosis from 2001 to 2013 were included. The risk windows were defined as pre-FQ start, FQ-exposed, and post-FQ completion. Incidence rate ratios were estimated in all risk windows and compared with baseline periods. A post hoc subgroup analysis was conducted to examine the effect of patients with a history of seizure. RESULTS: An increased incidence rate ratio was found in the pre-FQ start periods and no association was found in the post-FQ completion periods in both databases. The crude absolute risk of an incident seizure in 10,000 oral FQ prescriptions was 0.72 (95% confidence interval 0.47-1.10) in the Clinical Data Analysis and Reporting System and 0.40 (95% confidence interval 0.30-0.54) in the Clinical Practice Research Datalink. The rate ratio during treatment was not higher than pre-FQ start periods among patients with a history of seizure, therefore the results did not raise serious concerns. CONCLUSIONS: This study does not support a causal association between the use of oral FQs and the subsequent occurrence of seizure. An increased risk before the FQ exposure period suggests that the clinical indication for which FQ was prescribed may have contributed to the development of seizure rather than the drug itself