Risk factors for non compliance using occlusive therapy: a case study

Purpose: compliance with treatment is a common problem when treating amblyopic patients. Visual acuity of amblyopic eye does not improve without effective occlusive therapy. The aim of this study is to identify potential risk factors of non-compliance with treatment when it is implemented by family in amblyopic children. Setting: a quantitative transversal study was performed in a public hospital and in a private clinic in Lisbon.

Equilibrium self-assembly of colloids with distinct interaction sites: Thermodynamics, percolation, and cluster distribution functions

We calculate the equilibrium thermodynamic properties, percolation threshold, and cluster distribution functions for a model of associating colloids, which consists of hard spherical particles having on their surfaces three short-ranged attractive sites (sticky spots) of two different types, A and B. The thermodynamic properties are calculated using Wertheim's perturbation theory of associating fluids. This also allows us to find the onset of self-assembly, which can be quantified by the maxima of the specific heat at constant volume. The percolation threshold is derived, under the no-loop assumption, for the correlated bond model: In all cases it is two percolated phases that become identical at a critical point, when one exists. Finally, the cluster size distributions are calculated by mapping the model onto an effective model, characterized by a-state-dependent-functionality (f) over bar and unique bonding probability (p) over bar. The mapping is based on the asymptotic limit of the cluster distributions functions of the generic model and the effective parameters are defined through the requirement that the equilibrium cluster distributions of the true and effective models have the same number-averaged and weight-averaged sizes at all densities and temperatures. We also study the model numerically in the case where BB interactions are missing. In this limit, AB bonds either provide branching between A-chains (Y-junctions) if epsilon(AB)/epsilon(AA) is small, or drive the formation of a hyperbranched polymer if epsilon(AB)/epsilon(AA) is large. We find that the theoretical predictions describe quite accurately the numerical data, especially in the region where Y-junctions are present. There is fairly good agreement between theoretical and numerical results both for the thermodynamic (number of bonds and phase coexistence) and the connectivity properties of the model (cluster size distributions and percolation locus).

Percolation of colloids with distinct interaction sites

We generalize the Flory-Stockmayer theory of percolation to a model of associating (patchy) colloids, which consists of hard spherical particles, having on their surfaces f short-ranged-attractive sites of m different types. These sites can form bonds between particles and thus promote self-assembly. It is shown that the percolation threshold is given in terms of the eigenvalues of a m x m matrix, which describes the recursive relations for the number of bonded particles on the ith level of a cluster with no loops; percolation occurs when the largest of these eigenvalues equals unity. Expressions for the probability that a particle is not bonded to the giant cluster, for the average cluster size and the average size of a cluster to which a randomly chosen particle belongs, are also derived. Explicit results for these quantities are computed for the case f = 3 and m = 2. We show how these structural properties are related to the thermodynamics of the associating system by regarding bond formation as a (equilibrium) chemical reaction. This solution of the percolation problem, combined with Wertheim's thermodynamic first-order perturbation theory, allows the investigation of the interplay between phase behavior and cluster formation for general models of patchy colloids.

Non-selective optical wavelength-division multiplexing devices based on a-SiC:H multilayer heterostuctures

In this paper we present results on the optimization of multilayered a-SiC:H heterostructures for wavelength-division (de) multiplexing applications. The non selective WDM device is a double heterostructure in a glass/ITO/a-SiC:H (p-i-n) /a-SiC:H(-p) /a-Si:H(-i')/a-SiC:H (-n')/ITO configuration. The single or the multiple modulated wavelength channels are passed through the device, and absorbed accordingly to its wavelength, giving rise to a time dependent wavelength electrical field modulation across it. The effect of single or multiple input signals is converted to an electrical signal to regain the information (wavelength, intensity and frequency) of the incoming photogenerated carriers. Here, the (de) multiplexing of the channels is accomplished electronically, not optically. This approach offers advantages in terms of cost since several channels share the same optical components; and the electrical components are typically less expensive than the optical ones. An electrical model gives insight into the device operation.

A non-pixel image reader for continuous image detection based on tandem heterostructures

An optically addressed read-write sensor based on two stacked p-i-n heterojunctions is analyzed. The device is a two terminal image sensing structure. The charge packets are injected optically into the p-i-n writer and confined at the illuminated regions changing locally the electrical field profile across the p-i-n reader. An optical scanner is used for charge readout. The design allows a continuous readout without the need for pixel-level patterning. The role of light pattern and scanner wavelengths on the readout parameters is analyzed. The optical-to-electrical transfer characteristics show high quantum efficiency, broad spectral response, and reciprocity between light and image signal. A numerical simulation supports the imaging process. A black and white image is acquired with a resolution around 20 mum showing the potentiality of these devices for imaging applications.

Stacked photo-sensing devices based on SiC alloys A non-pixelled architecture for imagers and demultiplexing devices

In this review paper different designs based on stacked p-i'-n-p-i-n heterojunctions are presented and compared with the single p-i-n sensing structures. The imagers utilise self-field induced depletion layers for light detection and a modulated laser beam for sequential readout. The effect of the sensing element structure, cell configurations (single or tandem), and light source properties (intensity and wavelength) are correlated with the sensor output characteristics (light-to-dark sensivity, spatial resolution, linearity and S/N ratio). The readout frequency is optimized showing that scans speeds up to 104 lines per second can be achieved without degradation in the resolution. Multilayered p-i'-n-p-i-n heterostructures can also be used as wavelength-division multiplexing /demultiplexing devices in the visible range. Here the sensor element faces the modulated light from different input colour channels, each one with a specific wavelength and bit rate. By reading out the photocurrent at appropriated applied bias, the information is multiplexed or demultiplexed and can be transmitted or recovered again. Electrical models are present to support the sensing methodologies.

A model to forecast financial failure, in non financial galician SMES

We are concerned with providing more empirical evidence on forecast failure, developing forecast models, and examining the impact of events such as audit reports. A joint consideration of classic financial ratios and relevant external indicators leads us to build a basic prediction model focused in non-financial Galician SMEs. Explanatory variables are relevant financial indicators from the viewpoint of the financial logic and financial failure theory. The paper explores three mathematical models: discriminant analysis, Logit, and linear multivariate regression. We conclude that, even though they both offer high explanatory and predictive abilities, Logit and MDA models should be used and interpreted jointly.

Preferências no exercício físico em mulheres portuguesas sobreviventes de cancro da mama

Introdução – Os benefícios do exercício físico em sobreviventes de cancro da mama têm sido reportados; contudo, a sua prática permanece baixa, tornando importante o conhecimento dos fatores que promovam a motivação e adesão ao exercício nesta população. Objetivos – Identificar as preferências quanto à programação e aconselhamento do exercício físico de uma amostra da população de mulheres portuguesas sobreviventes de cancro da mama e averiguar a influência das variáveis demográficas e médicas nestas preferências. Método – Foi aplicado um questionário a uma amostra não probabilística sequencial de 26 mulheres sobreviventes de cancro da mama. Resultados – A amostra era maioritariamente constituída por mulheres entre os 45 e os 62 anos, casadas ou em união de facto, com ensino básico, empregadas e com Índice de Massa Corporal (IMC) > 24,4. Maioritariamente tinham realizado cirurgia radical há um mês ou mais, apresentavam estadio I do tumor, efetuavam quimioterapia como tratamento adjuvante e algumas realizavam classes de fisioterapia. A maioria das participantes demonstrava interesse em receber aconselhamento, sentia-se apta a participar num programa de exercício, preferia receber aconselhamento face-a-face no hospital e acompanhada por outros doentes oncológicos. O exercício deveria ser supervisionado e com intensidade moderada, sendo as caminhadas o tipo de exercício preferido. Não foi estatisticamente possível realizar a associação entre as variáveis demográficas e médicas e as preferências. Conclusão – Alguns resultados obtidos estão em concordância com estudos prévios; contudo, outros divergem destes. Os resultados obtidos podem fornecer informações importantes para a construção futura de programas de exercício para esta população. ABSTRACT - Introduction – The benefits of physical exercise in cancer survivors have been reported, although it’s practice remains low, becoming important the acknowledgement of the factors that promote the motivation and adhesion of physical exercise in this population. Objectives – To identify the preferences about programming and counseling of physical exercise inside a population-based sample of Portuguese women who have survived breast cancer. We also intend to investigate the influence of demographic and medical variables in those preferences. Method – A questionnaire was applied to a non-probabilistic sequential sample of 26 women that have survived breast cancer. Results – Our sample was mainly composed by women aged between 45 and 62, married or in a cohabitation state, with basic instruction, employed and with a Body Mass Index (BMI)> 24.4. Most of them have had radical mastectomy for at least one month, had the Stage I of the tumor, and had done chemotherapy as an adjuvant treatment and some of them were practicing post-surgery physical therapy. The majority of participants showed interest in receiving counseling, felt able to participate in an exercise program, preferred receiving face-to-face counseling, at the hospital and with other cancer patients. The exercise should be supervised and with a moderate intensity. Walking was their preferred choice of exercise. It was not statistically possible to establish the relationship between demographic and medical variables and those preferences. Conclusion – Some results are in agreement with previous studies; however, others diverge from these. The results obtained can provide important information for future construction of exercise programs for this population.

Avaliação e controlo da dor em pediatria: uma década

Introdução – A negligência no controlo da dor é um problema amplamente reconhecido em Portugal. Desde 2001 têm sido realizadas inúmeras iniciativas para melhorar a prática de cuidados nesta área. Desenvolveram-se ações de sensibilização e formação dos profissionais de saúde, publicaram-se orientações técnicas e guias de boas práticas e realizaram-se os primeiros estudos para se fazer um diagnóstico da situação. Objetivos – O objetivo deste trabalho foi o de caracterizar os cuidados prestados na avaliação e no controlo da dor nas crianças até aos 18 anos internadas em serviços hospitalares em Portugal e analisar a evolução feita nos cuidados entre os anos de 2002 e 2012. Metodologia – Estudo descritivo, transversal, de consulta retrospetiva seriada de registos intermitentes efetuados no processo clínico em relação a um período de 24 horas. O recrutamento da amostra foi aleatório e incluiu todos os processos clínicos de crianças até aos 18 anos internados em serviços de quatro hospitais Portugueses entre agosto e dezembro de 2011. Resultados – A prevalência de dor reduziu de forma significativa entre 2002 e 2012. As crianças livres de dor subiram de 37% para 75%. O registo da avaliação da intensidade da dor e a colheita de informação sobre a história de dor passou a ser uma prática comum na maioria dos casos (53% e 64%, respetivamente), embora ainda direcionada para o modelo de cuidados biomédico. A prevalência das intervenções farmacológicas não se alterou (43% versus 42%), mas a implementação de estratégias não-farmacológicas baixou significativamente (72% versus 15%). Conclusões – As ações de sensibilização/formação realizadas no âmbito das políticas implementadas nestes últimos dez anos na área da avaliação e controlo da dor pediátrica geraram evidentes ganhos na qualidade de cuidados prestados, pelo que o investimento na formação deve continuar. No entanto, deve ser dada prioridade à formação para a aplicação de estratégias de intervenção não-farmacológicas e ao desenvolvimento de mais investigação que suporte as práticas.

Symbolic dynamics and renormalization of non-autonomous k periodic dynamical systems

The purpose of this paper was to introduce the symbolic formalism based on kneading theory, which allows us to study the renormalization of non-autonomous periodic dynamical systems.

Endocardite infecciosa e acidente vascular cerebral: mecanismos fisiopatológicos e avaliação ultrassonográfica

Uma das mais graves complicações da endocardite infecciosa é o acidente vascular cerebral isquémico, responsável por uma alta taxa de mortalidade e morbilidade nos países desenvolvidos. Embora não seja o mecanismo dominante, o cardioembolismo é responsável por cerca de 20% dos enfartes cerebrais isquémicos. Sabe-se que o embolismo cerebral afeta mais de 40% dos pacientes com endocardite infecciosa, uma vez que a embolização da vegetação resultante da infeção das estruturas intracardíacas para a circulação arterial pode levar à oclusão das artérias cerebrais, dando origem, assim, a enfarte por ausência de aporte sanguíneo. O desenvolvimento de técnicas não invasivas baseadas na ultrassonografia tem potenciado um amplo estudo destas patologias, quer a nível cardíaco, quer vascular, promovendo uma melhor compreensão dos mecanismos fisiopatológicos que as envolvem. A ecocardiografia e o Doppler transcraniano detêm um papel central, respetivamente, no diagnóstico e predição do risco de fenómenos embólicos em pacientes com endocardite infecciosa e na avaliação inicial, prognóstico e follow-up de um episódio de acidente vascular cerebral.

Diagnosis of Tinea pedis and onychomycosis in patients from Portuguese National Institute of Health: a four-year study

ABSTRACT - Tinea pedis and onychomycosis are two rather diverse clinical manifestations of superficial fungal infections, and their etiologic agents may be dermatophytes, non-dermatophyte moulds or yeasts. This study was designed to statistically describe the data obtained as results of analysis conducted during a four year period on the frequency of Tinea pedis and onychomycosis and their etiologic agents. A questionnaire was distributed from 2006 to 2010 and answered by 186 patients, who were subjected to skin and/or nail sampling. Frequencies of the isolated fungal species were cross-linked with the data obtained with the questionnaire, seeking associations and predisposing factors. One hundred and sixty three fungal isolates were obtained, 24.2% of which composed by more than one fungal species. Most studies report the two pathologies as caused primarily by dermatophytes, followed by yeasts and lastly by non-dermatophytic moulds. Our study does not challenge this trend. We found a frequency of 15.6% of infections caused by dermatophytes (with a total of 42 isolates) of which T. rubrum was the most frequent species (41.4%). There was no significant association (p >0.05) among visible injury and the independent variables tested, namely age, gender, owning pet, education, swimming pools attendance, sports activity and clinical information. Unlike other studies, the variables considered did not show the expected influence on dermatomycosis of the lower limbs. It is hence necessary to conduct further studies to specifically identify which variables do in fact influence such infections.

Non-coding RNAs: multi-tasking molecules in the cell

In the last years it has become increasingly clear that the mammalian transcriptome is highly complex and includes a large number of small non-coding RNAs (sncRNAs) and long noncoding RNAs (lncRNAs). Here we review the biogenesis pathways of the three classes of sncRNAs, namely short interfering RNAs (siRNAs), microRNAs (miRNAs) and PIWI-interacting RNAs (piRNAs). These ncRNAs have been extensively studied and are involved in pathways leading to specific gene silencing and the protection of genomes against virus and transposons, for example. Also, lncRNAs have emerged as pivotal molecules for the transcriptional and post-transcriptional regulation of gene expression which is supported by their tissue-specific expression patterns, subcellular distribution, and developmental regulation. Therefore, we also focus our attention on their role in differentiation and development. SncRNAs and lncRNAs play critical roles in defining DNA methylation patterns, as well as chromatin remodeling thus having a substantial effect in epigenetics. The identification of some overlaps in their biogenesis pathways and functional roles raises the hypothesis that these molecules play concerted functions in vivo, creating complex regulatory networks where cooperation with regulatory proteins is necessary. We also highlighted the implications of biogenesis and gene expression deregulation of sncRNAs and lncRNAs in human diseases like cancer.

The use of non-standard CT conversion ramps for Monte Carlo verification of 6 MV prostate IMRT plans

Monte Carlo (MC) dose calculation algorithms have been widely used to verify the accuracy of intensity-modulated radiotherapy (IMRT) dose distributions computed by conventional algorithms due to the ability to precisely account for the effects of tissue inhomogeneities and multileaf collimator characteristics. Both algorithms present, however, a particular difference in terms of dose calculation and report. Whereas dose from conventional methods is traditionally computed and reported as the water-equivalent dose (Dw), MC dose algorithms calculate and report dose to medium (Dm). In order to compare consistently both methods, the conversion of MC Dm into Dw is therefore necessary. This study aims to assess the effect of applying the conversion of MC-based Dm distributions to Dw for prostate IMRT plans generated for 6 MV photon beams. MC phantoms were created from the patient CT images using three different ramps to convert CT numbers into material and mass density: a conventional four material ramp (CTCREATE) and two simplified CT conversion ramps: (1) air and water with variable densities and (2) air and water with unit density. MC simulations were performed using the BEAMnrc code for the treatment head simulation and the DOSXYZnrc code for the patient dose calculation. The conversion of Dm to Dw by scaling with the stopping power ratios of water to medium was also performed in a post-MC calculation process. The comparison of MC dose distributions calculated in conventional and simplified (water with variable densities) phantoms showed that the effect of material composition on dose-volume histograms (DVH) was less than 1% for soft tissue and about 2.5% near and inside bone structures. The effect of material density on DVH was less than 1% for all tissues through the comparison of MC distributions performed in the two simplified phantoms considering water. Additionally, MC dose distributions were compared with the predictions from an Eclipse treatment planning system (TPS), which employed a pencil beam convolution (PBC) algorithm with Modified Batho Power Law heterogeneity correction. Eclipse PBC and MC calculations (conventional and simplified phantoms) agreed well (<1%) for soft tissues. For femoral heads, differences up to 3% were observed between the DVH for Eclipse PBC and MC calculated in conventional phantoms. The use of the CT conversion ramp of water with variable densities for MC simulations showed no dose discrepancies (0.5%) with the PBC algorithm. Moreover, converting Dm to Dw using mass stopping power ratios resulted in a significant shift (up to 6%) in the DVH for the femoral heads compared to the Eclipse PBC one. Our results show that, for prostate IMRT plans delivered with 6 MV photon beams, no conversion of MC dose from medium to water using stopping power ratio is needed. In contrast, MC dose calculations using water with variable density may be a simple way to solve the problem found using the dose conversion method based on the stopping power ratio.

Modelos de acompanhamento e controlo de natureza estratégica e o relato financeiro

Mestrado em Contabilidade Internacional