Evidence of portuguese stock market abnormal returns

According to the stock market efficiency theory, it is not possible to consistently beat the market. However, technical analysis is more and more spread as an efficient way to achieve abnormal returns. In fact there is evidence that momentum investing strategies provide abnormal returns in different stock markets, Jegadeesh, N. and Titman, S. (1993), George, T. and Hwang, C. (2004) and Du, D. (2009). In this work we study if like other markets, the Portuguese stock market also allows to obtain abnormal returns, using a strategy that consists in picking stocks according to their past performance. Our work confirms the results of Soares, J. and Serra, A. (2005) and Pereira, P. (2009), showing that an investor can get abnormal returns investing in momentum portfolios. The Portuguese stock market evidences momentum returns in short term, exhibiting reversal in long term.

Arrow Plot: a new graphical tool for selecting up and down regulated genes and genes differentially expressed on samples subgroups

Background: A common task in analyzing microarray data is to determine which genes are differentially expressed across two (or more) kind of tissue samples or samples submitted under experimental conditions. Several statistical methods have been proposed to accomplish this goal, generally based on measures of distance between classes. It is well known that biological samples are heterogeneous because of factors such as molecular subtypes or genetic background that are often unknown to the experimenter. For instance, in experiments which involve molecular classification of tumors it is important to identify significant subtypes of cancer. Bimodal or multimodal distributions often reflect the presence of subsamples mixtures. Consequently, there can be genes differentially expressed on sample subgroups which are missed if usual statistical approaches are used. In this paper we propose a new graphical tool which not only identifies genes with up and down regulations, but also genes with differential expression in different subclasses, that are usually missed if current statistical methods are used. This tool is based on two measures of distance between samples, namely the overlapping coefficient (OVL) between two densities and the area under the receiver operating characteristic (ROC) curve. The methodology proposed here was implemented in the open-source R software. Results: This method was applied to a publicly available dataset, as well as to a simulated dataset. We compared our results with the ones obtained using some of the standard methods for detecting differentially expressed genes, namely Welch t-statistic, fold change (FC), rank products (RP), average difference (AD), weighted average difference (WAD), moderated t-statistic (modT), intensity-based moderated t-statistic (ibmT), significance analysis of microarrays (samT) and area under the ROC curve (AUC). On both datasets all differentially expressed genes with bimodal or multimodal distributions were not selected by all standard selection procedures. We also compared our results with (i) area between ROC curve and rising area (ABCR) and (ii) the test for not proper ROC curves (TNRC). We found our methodology more comprehensive, because it detects both bimodal and multimodal distributions and different variances can be considered on both samples. Another advantage of our method is that we can analyze graphically the behavior of different kinds of differentially expressed genes. Conclusion: Our results indicate that the arrow plot represents a new flexible and useful tool for the analysis of gene expression profiles from microarrays.

Factors influencing amblyopia rehabilitation in occlusive therapy

Amblyopia develops in an early period and is a decrease of visual acuity (unilateral or bilateral) caused by a deprivation of vision or abnormal binocular interaction. Prognosis of Amblyopia is better when occlusive treatment is implemented in an early stage. Visual acuity of amblyopic eye does not improve without effective occlusive therapy. The aim of this study is to identify potential risk factors of noncompliance with treatment when it is implemented by parents in amblyopic children.

Magma flow, exsolution processes and rock metasomatism in the Great Messejana-Plasencia dyke (Iberian Peninsula)

Magma flow in dykes is still not well understood; some reported magnetic fabrics are contradictory and the potential effects of exsolution and metasomatism processes on the magnetic properties are issues open to debate. Therefore, a long dyke made of segments with different thickness, which record distinct degrees of metasomatism, the Messejana-Plasencia dyke (MPD), was studied. Oriented dolerite samples were collected along several cross-sections and characterized by means of microscopy and magnetic analyses. The results obtained show that the effects of metasomatism on rock mineralogy are important, and that the metasomatic processes can greatly influence anisotropy degree and mean susceptibility only when rocks are strongly affected by metasomatism. Petrography, scanning electron microscopy (SEM) and bulk magnetic analyses show a high-temperature oxidation-exsolution event, experienced by the very early Ti-spinels, during the early stages of magma cooling, which was mostly observed in central domains of the thick dyke segments. Exsolution reduced the grain size of the magnetic carrier (multidomain to single domain transformation), thus producing composite fabrics involving inverse fabrics. These are likely responsible for a significant number of the 'abnormal' fabrics, which make the interpretation of magma flow much more complex. By choosing to use only the 'normal' fabric for magma flow determination, we have reduced by 50 per cent the number of relevant sites. In these sites, the imbrication angle of the magnetic foliation relative to dyke wall strongly suggests flow with end-members indicating vertical-dominated flow (seven sites) and horizontal-dominated flow (three sites).

Shareholder wealth creation in response to announcements of acquisitions of unlisted firms: Evidence from Spain

We investigate shareholder value creation of Spanish listed firms in response to announcements of acquisitions of unlisted companies and compare this experience to the purchase of listed firms over the period 1991–2006. Similar to foreign markets, acquirers of listed targets earn insignificant average abnormal returns, whereas acquirers of unlisted targets gain significant positive average abnormal returns. When we relate these results to company and transaction characteristics our findings diverge from those reported in the literature for other foreign markets, as our evidence suggests that the listing status effect is mainly associated with the fact that unlisted firms tend to be smaller and lesser–known firms, and thus suffer from a lack of competition in the market for corporate control. Consequently, the payment of lower premiums and the possibility of diversifying shareholders’ portfolios lead to unlisted firm acquisitions being viewed as value–orientated transactions.

The impact of family control on firm's return

Family firm is a field of growing interest. The aim of this article is to understand whether CEOs identity impacts family firm’s stock returns. From a sample of Portuguese and Spanish family firms findings show that who manages the firms result in significantly different risk exposure. Moreover, we find that the abnormal return found by Fahlenbrach (2009) to founder-controlled firms disappear when we use valueweighted portfolios and include two new factors: market aggregate illiquidity and debt intensity to the four-factor Carhart model. Finally, our results explain why the majority of family firm is controlled by its founder.

Mob1: defining cell polarity for proper cell division

Mob1 is a component of both the mitotic exit network and Hippo pathway, being required for cytokinesis, control of cell proliferation and apoptosis. Cell division accuracy is crucial in maintaining cell ploidy and genomic stability and relies on the correct establishment of the cell division axis, which is under the control of the cell's environment and its intrinsic polarity. The ciliate Tetrahymena thermophila possesses a permanent anterior-posterior axis, left-right asymmetry and divides symmetrically. These unique features of Tetrahymena prompted us to investigate the role of Tetrahymena Mob1. Unexpectedly, we found that Mob1 accumulated in basal bodies at the posterior pole of the cell, and is the first molecular polarity marker so far described in Tetrahymena. In addition, Mob1 depletion caused the abnormal establishment of the cell division plane, providing clear evidence that Mob1 is important for its definition. Furthermore, cytokinesis was arrested and ciliogenesis delayed in Tetrahymena cells depleted of Mob1. This is the first evidence for an involvement of Mob1 in cilia biology. In conclusion, we show that Mob1 is an important cell polarity marker that is crucial for correct division plane placement, for cytokinesis completion and for normal cilia growth rates.

O papel da supervisão na avaliação de desempenho docente

Com as várias reformulações do processo de avaliação de desempenho docente (ADD), passou-se de um processo de avaliação dos professores assente na autoavaliação do docente, para um sistema de heteroavaliação que visa a prestação de contas e a seleção, mas também a melhoria de práticas e o desenvolvimento profissional, através do acompanhamento supervisivo. No entanto, a conciliação entre estas duas perspetivas não é fácil e tem gerado perplexidades e inquietações entre os avaliadores e entre os avaliados. Com este estudo, pretendemos conhecer a perspetiva de avaliadores e avaliados sobre o papel que a Supervisão detém no processo de avaliação de desempenho do professor e o seu contributo para o desenvolvimento profissional do professor e melhoria das práticas. Assim desenhou-se um plano de estudo qualitativo, exploratório e descritivo procurando captar o ponto de vista dos principais intervenientes no processo. O principal meio de recolha de dados foi a entrevista semiestruturada a 4 professores avaliadores e 4 professores avaliados do Departamento de Matemática e Ciências Experimentais de um Agrupamento de Escolas. Os resultados mostram que os docentes discordam do modelo de ADD, mas que o processo vivenciado teve caraterísticas positivas, dando os avaliadores especial relevância à oportunidade de conhecer outros processos de trabalho, a partir da observação de aulas. Avaliadores e avaliados referem ainda o bom relacionamento estabelecido entre ambos, contradizendo as preocupações expressas quando se pronunciaram sobre os problemas do modelo de avaliação. No entanto, ambos os subgrupos focam a falta de formação e qualificação profissional dos avaliadores. Em termos gerais, é possível concluir que a maior parte das dificuldades atribuídas pelos docentes ao modelo de ADD não foi depois sentida na implementação prática. Por outro lado, na opinião dos docentes, o processo experienciado não teve verdadeiro impacto na melhoria das práticas ou no desenvolvimento profissional dos docentes envolvidos. - Abstract The several reformulations of the process of the teacher performance evaluation made the process of evaluating teachers, which was first based on a self-evaluation change into a straight assessment system, which aims not only accountability and selection, but also the improvement of the practice and professional development through the supervision of the teaching practice. However, the conciliation between these perspectives has not been easy and has generated anxieties and perplexities among evaluators and evaluated. With this study we intend to know the perspective of the evaluators and of the evaluated concerning the role supervision has hold in the process of evaluating a teacher’s performance and its contribution to the professional development of the teacher and to the improvement of his practices. Thus, a qualitative, exploratory and descriptive study plan was drawn to get to know the viewpoint of the intervening ones in the process. The main means for data collection was based on a semi structured interview, targeting 4 teacher evaluators and 4 evaluated teachers of the Experimental Sciences and Mathematics Department of a group of Schools. The results show that teachers disagree with the teacher’s evaluation model, but the experienced process had positive characteristics. Besides, evaluators have given special relevance to the opportunity of getting to know other working methods thanks to the lessons’ observations. Evaluators and evaluated also refer the good relationship between both parts contradicting the fears they had when they first pronounced themselves about this evaluation model. However, both subgroups focus the lack of training and professional qualifications of the evaluators. So it’s possible to conclude that most worries mentioned by the teachers when referring to this model of teacher performance evaluation were not verified during its practical implementation. On the other hand, in the opinion of the involved teachers, the experienced process had no real impact on their practice improvement or on their professional development.

Synthesis of optimization of [11C] Pittsburgh compound B by the captive solvent method

Mestrado em Medicina Nuclear.

Binocular vision and reading ability in a Portuguese population of school age children

Preventable visual loss caused by amblyopia (2 to 4%) and its risk factors such as strabismus (3%) and uncorrected refractive errors (5 to 7%) represent an important public health problem. Children with binocular vision anomalies could be at disadvantage in reading and writing. Objectives: (1) Describe binocular vision measures in children of school age; and (2) Describe the impact of abnormal binocular vision on reading ability (reading errors and reading speed).

Data mining framework for fatty liver disease classification in ultrasound: a hybrid feature extraction paradigm

PURPOSE: Fatty liver disease (FLD) is an increasing prevalent disease that can be reversed if detected early. Ultrasound is the safest and ubiquitous method for identifying FLD. Since expert sonographers are required to accurately interpret the liver ultrasound images, lack of the same will result in interobserver variability. For more objective interpretation, high accuracy, and quick second opinions, computer aided diagnostic (CAD) techniques may be exploited. The purpose of this work is to develop one such CAD technique for accurate classification of normal livers and abnormal livers affected by FLD. METHODS: In this paper, the authors present a CAD technique (called Symtosis) that uses a novel combination of significant features based on the texture, wavelet transform, and higher order spectra of the liver ultrasound images in various supervised learning-based classifiers in order to determine parameters that classify normal and FLD-affected abnormal livers. RESULTS: On evaluating the proposed technique on a database of 58 abnormal and 42 normal liver ultrasound images, the authors were able to achieve a high classification accuracy of 93.3% using the decision tree classifier. CONCLUSIONS: This high accuracy added to the completely automated classification procedure makes the authors' proposed technique highly suitable for clinical deployment and usage.

Fatty liver characterization and classification by ultrasound

Steatosis, also known as fatty liver, corresponds to an abnormal retention of lipids within the hepatic cells and reflects an impairment of the normal processes of synthesis and elimination of fat. Several causes may lead to this condition, namely obesity, diabetes, or alcoholism. In this paper an automatic classification algorithm is proposed for the diagnosis of the liver steatosis from ultrasound images. The features are selected in order to catch the same characteristics used by the physicians in the diagnosis of the disease based on visual inspection of the ultrasound images. The algorithm, designed in a Bayesian framework, computes two images: i) a despeckled one, containing the anatomic and echogenic information of the liver, and ii) an image containing only the speckle used to compute the textural features. These images are computed from the estimated RF signal generated by the ultrasound probe where the dynamic range compression performed by the equipment is taken into account. A Bayes classifier, trained with data manually classified by expert clinicians and used as ground truth, reaches an overall accuracy of 95% and a 100% of sensitivity. The main novelties of the method are the estimations of the RF and speckle images which make it possible to accurately compute textural features of the liver parenchyma relevant for the diagnosis.

Psychosocial factors as predictors of quality of life in chronic portuguese patients

Background - Chronic illnesses are diseases of long duration and generally of slow progression. They cause significant quality of life impairment. The aim of this study was to analyse psychosocial predictors of quality of life and of subjective well-being in chronic Portuguese patients. Methods - Chronic disease patients (n = 774) were recruited from central Portuguese Hospitals. Participants completed self-reported questionnaires assessing socio-demographic, clinical, psychosocial and outcome variables: quality of life (HRQL) and subjective well-being (SWB). MANCOVA analyses were used to test psychosocial factors as determinants of HRQL and SWB. Results - After controlling for socio-demographic and clinical variables, results showed that dispositional optimism, positive affect, spirituality, social support and treatment adherence are significant predictors of HRQL and SWB. Similar predictors of quality of life, such as positive affect, treatment adherence and spirituality, were found for subgroups of disease classified by medical condition. Conclusions - The work identifies psychosocial factors associated with quality of life. The predictors for the entire group of different chronic diseases are similar to the ones found in different chronic disease subgroups: positive affect, social support, treatment adherence and spirituality. Patients with more positive affect, additional social support, an adequate treatment adherence and a feel-good spirituality, felt better with the disease conditions and consequently had a better quality of life. This study contributes to understanding and improving the processes associated with quality of life, which is relevant for health care providers and chronic diseases support.

Eu também ando na escola: a escola quando a criança tem doença crónica

A Escola é o primeiro e mais importante contexto de vida e de desenvolvimento da criança depois do seu “casulo” família. Espera-se que seja na Escola que a criança passe grande parte dos seus dias. Para muitas crianças, no entanto, a vivência Escolar é intercalada ou misturada com outras vivências potencialmente stressantes e desafiadoras do seu desenvolvimento e sua construção de identidade. As crianças com Doença Crónica fazem parte desse grupo, são crianças normais em situações anormais. Baseado na literatura e em experiências de crianças com doença crónica, serão abordados, neste artigo, alguns problemas, preocupações e necessidades, no âmbito da Escola, destas crianças e das suas famílias. Tentando “trazer respostas” serão ainda apontados possíveis contributos para a minoração dos problemas enunciados.

Avaliação de desempenho docente: efeitos no desenvolvimento profissional.

Dissertação apresentada à Escola Superior de Educação de Lisboa para obtenção de grau de mestre em Ciências da Educação - Especialização Supervisão em Educação