Tensile creep of a structural epoxy adhesive: experimental and analytical characterization

Epoxy adhesives are nowadays being extensively used in Civil Engineering applications, mostly in the scope of the rehabilitation of reinforced concrete (RC) structures. In this context, epoxy adhesives are used to provide adequate stress transference from fibre reinforced polymers (FRP) to the surrounding concrete substrate. Most recently, the possibility of using prestressed FRPs bonded with these epoxy adhesives is also being explored in order to maximize the potentialities of this strengthening approach. In this context, the understanding of the long term behaviour of the involved materials becomes essential. Even when non-prestressed FRPs are used a certain amount of stress is permanently applied on the adhesive interface during the serviceability conditions of the strengthened structure, and the creep of the adhesive may cause a continuous variation in the deformational response of the element. In this context, this paper presents a study aiming to experimentally characterize the tensile creep behaviour of an epoxy-based adhesive currently used in the strengthening of concrete structures with carbon FRP (CFRP) systems. To analytically describe the tensile creep behaviour, the modified Burgers model was fitted to the experimental creep curves, and the obtained results revealed that this model is capable of predicting with very good accuracy the long term behaviour of this material up to a sustained stress level of 60% of the adhesive’s tensile strength.

José Anastácio da Cunha e o projeto MAT² : no trilho de uma história extraordinária

A ideia de que as Matemáticas de Portugal (e de Espanha) atravessaram, depois de um período áureo nos Descobrimentos, um longo deserto onde não foi possível florescerem Mestres, nem escolas, nem cultura científica, nem investigação de relevo foi, durante muito tempo, reiteradamente veiculada, inclusivé através de alguns dos nossos mais referenciados historiadores da Matemática, como é o caso de Gomes Teixeira ou de Rey Pastor. Mas a verdade é que o estudo da História das Matemáticas em Portugal tem, na última década, vivido um interesse crescente onde sobressaem, em particular, uma leitura menos enviesada sobre, por exemplo, o papel educativo dos Jesuítas ou a publicação das obras completas de Pedro Nunes. Está-se assim a contribuir para uma compreensão mais completa da História geral de Portugal, de que a História da Ciência e da Cultura faz parte. José Anastácio da Cunha (1744-1787) foi figura de proa no século XVIII português. Sabíamo-lo matemático que, sem nunca ter saído de Portugal, havia sido capaz de antecipar, em mais de 50 anos, os esforços de matemáticos franceses e alemães para fundar a Matemática com rigor. Sabíamo-lo também autor de uma vasta e diversificada obra de inegável importância matemática mas, igualmente, autor de textos poéticos. Agora, com o projecto que denominámos de MAT2, centramo-nos em José Anastácio da Cunha e pretendemos, se possível, ir ainda mais além. Partimos de uma descoberta, árdua mas com final feliz, em um Arquivo de família: o da Casa de Mateus. Sentimo-nos, com esta “sorte”, privilegiados e gratos por nos ter sido gentilmente concedido o acesso a um vasto conjunto de documentos únicos (diários de viagens, notas de aulas e correspondência) que incluem memórias autógrafas e inéditas de Anastácio da Cunha. Organizámo-nos, cientes do trabalho árduo que temos pela frente, multi e interdisciplinarmente englobando a Matemática (nas suas múltiplas especializações) e a História (incluindo a da Matemática) mas também contando com a Física, a Informática, os estudos militares ou a Arquivística e as Humanidades; reunimos académicos, mais e menos veteranos, com investigadores jovens e juntámos valências nacionais e estrangeiras. No presente artigo daremos conta do percurso trilhado, até agora, pelo projecto MAT2.

Trabalhos para casa no 1.ºCiclo: ter ou não ter, eis a questão

Relatório de estágio de mestrado em Educação Pré-Escolar e Ensino do 1.º Ciclo do Ensino Básico

Ergonomic evaluation of office workplaces with Rapid Office Strain Assessment (ROSA)

The regular use of the computer in the office contributed to the appearance of many risk factors related with work-related musculoskeletal disorders (WRMSD) such as maintaining static sitting postures for long time and awkward postures of the head, neck and upper limbs, leading to increased muscle activity in the cervical spine and shoulders. The objective of this study was to evaluate the presence of risk factors for WRMSD in an office using the Rapid Assessment Office Strain method (ROSA). Based on the results of this ergonomic evaluation, an occupational gym program was designed and implemented. Thirty-eight workplaces were evaluated using the observation of the tasks and pictures records in order to characterize those tasks in more detail. The ROSA tool was applied by an observer, who selected the appropriate score based on the worker's posture as well as the time spent in each posture. Scores were recorded for the sections of the method, specifically Chair, Monitor and Mouse and Keyboard and Telephone. The scores were recorded in a sheet developed for the method. The mean ROSA final score was 3.61 ± 0.64, for Chair section was 3.45 ± 0.55, to Monitor and Telephone section was 3.11 ± 0.61, and to Mouse and Keyboard section was 2.11 ± 0.31. The results led to understand that the analyzed tasks represent situations of risk of discomfort and, according to the methods guidelines, further research and modifications of the workplace may be necessary. It should be emphasized that these scores may not be related to the poor available equipment but with the need to optimize their use by the workers. It was noticed also that the interaction of workers with the tasks and the adopted sitting posture at the computer throughout the day have effects at a muscular level, essentially for the cervical area and shoulders. ROSA tool is an useful and easy method to assess several risk factors associated with WRMSD, also allowing the design of specific occupational gym programs.

Design de superfície biomimética para aplicação em atividades desportivas

Tese de Doutoramento Engenharia Têxtil.

Os estereótipos de gênero na publicidade televisiva. Uma comparação entre spots publicitários brasileiros e portugueses

Tese de Doutoramento em Ciências da Comunicação (área de especialização em Comunicação Estratégica e Organizacional).

To be or not to be a pseudogene: a molecular epidemiological approach to the mclx genes and its impact in tuberculosis

Tuberculosis presents a myriad of symptoms, progression routes and propagation patterns not yet fully understood. Whereas for a long time research has focused solely on the patient immunity and overall susceptibility, it is nowadays widely accepted that the genetic diversity of its causative agent, Mycobacterium tuberculosis, plays a key role in this dynamic. This study focuses on a particular family of genes, the mclxs (Mycobacterium cyclase/LuxR-like genes), which codify for a particular and nearly mycobacterial-exclusive combination of protein domains. mclxs genes were found to be pseudogenized by frameshift-causing insertion(s)/deletion(s) in a considerable number of M. tuberculosis complex strains and clinical isolates. To discern the functional implications of the pseudogenization, we have analysed the pattern of frameshift-causing mutations in a group of M. tuberculosis isolates while taking into account their microbial-, patient- and disease-related traits. Our logistic regression-based analyses have revealed disparate effects associated with the transcriptional inactivation of two mclx genes. In fact, mclx2 (Rv1358) pseudogenization appears to be primarily driven by the microbial phylogenetic background, being mainly related to the Euro-American (EAm) lineage; on the other hand, mclx3 (Rv2488c) presents a higher tendency for pseudogenization among isolates from patients born on the Western Pacific area, and from isolates causing extra-pulmonary infections. These results contribute to the overall knowledge on the biology of M. tuberculosis infection, whereas at the same time launch the necessary basis for the functional assessment of these so far overlooked genes.

Políticas, processos e atores de privatização da educação em Portugal: apontamentos

Procurou-se contribuir para esboçar uma problemática de pesquisa em torno da privatização em educação, no quadro das relações entre o Estado e os domínios público e privado e tomando como horizonte a construção do direito fundamental à educação e do bem-estar social, situados no Portugal democrático. Argumentou-se que o Estado e as políticas públicas têm, nestes 40 anos, desempenhado um papel central naqueles processos. Durante muito tempo, com fases e combinações distintas, pode observar-se uma espécie de duplicidade na ação estatal, com o acento tónico ora na expansão e consolidação do sistema público, ora no apoio e sustentação de atores e dinâmicas de ampliação do espaço e da influência privados, às vezes assumindo simultaneamente uma e outra orientação em setores diferenciados. Sugere-se, no entanto, que, desde 2011, no quadro de políticas regressivas austeritárias de ajustamento estrutural, com origem na União Europeia, se assistiu a uma rutura em favor de um projeto societal neoliberal radical que, a ser bem sucedido, procura instituir um sistema educativo pobre para pobres e alterar o estatuto e o papel do direito à educação e do sistema público que constitucionalmente o realiza.

Literatura russa em Portugal: das vias de difusão aos sentidos de receção: o caso de Leão Tolstói

Tese de Doutoramento em Ciências da Literatura (área de especialização em Literatura Comparada).

Implementação de um sistema de previsão e controlo para operação otimizada de um sistema de recolha e armazenamento de água pluvial

Dissertação de mestrado integrado em Engenharia Civil

O stalking no ordenamento jurídico português: considerações empírico-jurídicas

Dissertação de mestrado em Crime, Diferença e Desigualdade

A estética audiovisual: o caso do Canal 180

Relatório de estágio de mestrado em Ciências da Comunicação (área de especialização em Audiovisual e Multimédia)

Fundamentos do jornalismo: uma proposta de objectividade

Dissertação de mestrado em Ciências da Comunicação (área de especialização em Informação e Jornalismo)

A compreensão dos problemas de estrutura aditiva e estrutura multiplicativa por crianças do pré-escolar

Tese de Doutoramento em Ciências da Educação (área de especialização em Educação Matemática).

Uma nova modalidade de sexo-determinação no grilo sul-americano eneoptera surinamensis

The male of Eneoptera surinamensis (Orthoptera-Eneopteridae) is provided with 9 chromosomes, that is, with 3 pairs of autosomes and 3 sex chromosomes. Spermatogonia. - The autosomes of the spermatogonia are of the same size and U-shaped. One of the sex chromosomes approximately equalling the autosomes in size is telocentric, while the other two are much larger and V-shaped. One of the latter is smaller than the other. The sex chromosomes as showed in Figs. 1 and 2 are designated by X, Yl and Y2, X being the larger V, Yl the smaller one and Y2 the rod-shaped. Primary spermatocytes. - Before the growth period of the spermatocytes all the three sex chromosomes are visible in a state of strong heteropycnosis. X is remarkable in this stage in having two long arms well separated by a wide commissural segment. (Figs. 4, 5 and 6). During the growth period Y2 disappears, while X and Yl remain in a condensed form until metaphase. These may be separated from one another or united in the most varied and irregular manner. (Fig. 7 to 12). In the latter case the segments in contact seem to be always different so that we cannot recognize any homology of parts in the sense os genetics. At diplotene Y2 reappears together with the autosomal tetrads. X and Yl may again be seen as separate or united elements. (Figs. 13 and 14). At later diakinesis and metaphase the three sex chromosomes are always independent from each other, Y2 being typically rod-shaped, X and Yl V-shaped, X being a little larger than Yl. (Fig. 15 to 18). At metaphase the three condensed tetrads go to the equatorial plane, while the sex chromosomes occupy any position at both sides of this plane. In almost all figures which could be perfectly analysed X appeared at one side of the autosomal plate an Yl together with Y2 far apart at the other side. (Figs. 16 and 18). Only a few exception have been found. (Figs. 17 and 19). At anaphase X goes in precession to one pole, Yl and Y2 to the other (Figs. 20 and 21). As it is suggested by the few figures in which a localization of the sex chromosomes different from the normal has been observed, the possibility of other types of segregation of these elements cannot be entirely precluded. But, if this does happen, the resulting gametes should be inviable or give inviable zygotes. Early in anaphase autosomes and sex chromosomes divide longitudinally, being maintained united only by the kinetochore. (Figs. 20 and 21). At metaphase the three sex chromosomes seem to show no special repulsion against each other, X being found in the proximity of Yl or Y2 indifferently. At anaphase, however, the evidences in hand point to a stronger repulsion between X on the one side and both Ys on the other, so that in spite of the mutual repulsion of the latter they finish by going to the same pole. Secondary spermatocytes. - At telophase of the primary spermatocytes all the chromosomes enter into distension without disappearing of view. A nuclear membrane is formed around the chromosomes. All the chromosomes excepting Y2 which has two arms, are four-branched. (Fig. 22). Soon the chromosomes enter again into contraction giving rise to the secondary metaphase plate. Secondary spermatocytes provided as expected with four and five chromosomes are abundantly found. (Figs. 23 and 24). In the former all chromosomes are X-shaped while in the latter there is one which is V-shaped. This is the rod- shaped Y2. In the anaphase of the spermatocytes with four chromosomes all the chromosomes are V-shaped, one of them (X) being much larger than the others. In those with five there is one rod-shaped chromosome (Y2). (Fig. 25), Spermatids. Two classes of spermatids are produced, one with X and other with Yl and Y2. All the autosomes as well as Y2 soon enter into solution, X remaining visible for long time in one class and Yl in the other. (Figs. 26 and 27). Since both are very alike at this stage, one cannot distinguish the two classes of spermatids. Somatic chromosomes in the famale. - In the follicular cells of the ovary 8 chromosomes were found, two of which are much larger than the rest. (Figs. 29 and 30). These are considered as being sex chromosomes. CONCLUSION: Eneoptera surinamensis has a new type of sex-determining mechanism, the male being X Yl Y2 and the female XX. The sex chromosomes segregate without entering into contact at metaphase or forming group. After a review of the other known cases of complex sex chromosome mechanism the author held that Eneoptera is the unique representative of a true determinate segregation of sex chromosomes. Y2 behaving as sex chromosome and as autosome is considered as representing an intermediary state of the evolution of the sex chromosomes.