Matemática discreta

Publicação pedagógicaO presente livro é um texto de apoio à unidade curricular Matemática Discreta e tem assim o objectivo de ser uma apresentação simples, mas cuidada, de conceitos e resultados básicos da Teoria de Grafos e da Teoria de Números

Evaluating delinquency policy interventions in Portugal

Social program and policies, interventions, and services, should be required to undergo rigorous systematic evaluation to address the policy question of how society should invest in the treatment of juvenile offenders in the institutional care system. Public policy decisions regarding programs for youths should be grounded on research-based knowledge and experience of academia and practitioners, program participants. Despite developments in intervention science, the existing empirical literature is seriously underdeveloped with respect to the issue of delinquency interventions and policies in Portugal. In other words, there is little systematic knowledge on the effects of existing policies in the youth system. In this paper, we address the available research and evidence on juvenile justice institutional interventions. We seek to explore the extent to which these are 1) informed by previous studies and 2) subject to analysis during and following policy termination.CIEC – Research Centre on Child Studies, IE, UMinho (FCT R&D unit 317), Portugal;National Funds through the FCT (Foundation for Science and Technology) and co-financed by European Regional Development Funds (FEDER) through the Competitiveness and Internationalization Operational Program (POCI) with the reference POCI-01-0145-FEDER-007562info:eu-repo/semantics/publishedVersio

Arp2/3 complex activity in filopodia of spreading cells

Background Cells use filopodia to explore their environment and to form new adhesion contacts for motility and spreading. The Arp2/3 complex has been implicated in lamellipodial actin assembly as a major nucleator of new actin filaments in branched networks. The interplay between filopodial and lamellipodial protrusions is an area of much interest as it is thought to be a key determinant of how cells make motility choices. Results We find that Arp2/3 complex localises to dynamic puncta in filopodia as well as lamellipodia of spreading cells. Arp2/3 complex spots do not appear to depend on local adhesion or on microtubules for their localisation but their inclusion in filopodia or lamellipodia depends on the activity of the small GTPase Rac1. Arp2/3 complex spots in filopodia are capable of incorporating monomeric actin, suggesting the presence of available filament barbed ends for polymerisation. Arp2/3 complex in filopodia co-localises with lamellipodial proteins such as capping protein and cortactin. The dynamics of Arp2/3 complex puncta suggests that they are moving bi-directionally along the length of filopodia and that they may be regions of lamellipodial activity within the filopodia. Conclusion We suggest that filopodia of spreading cells have regions of lamellipodial activity and that this activity affects the morphology and movement of filopodia. Our work has implications for how we understand the interplay between lamellipodia and filopodia and for how actin networks are generated spatially in cells

Associate inverse subsemigroups of regular semigroups

By an associate inverse subsemigroup of a regular semigroup S we mean a subsemigroup T of S containing a least associate of each x ∈ S, in relation to the natural partial order ≤S. We describe the structure of a regular semigroup with an associate inverse subsemigroup, satisfying two natural conditions. As a articular application, we obtain the structure of regular semigroups with an associate subgroup with medial identity element.Fundação para a Ciência e a Tecnologia (FCT

Some orthodox monoids with associate inverse subsemigroups

By an associate inverse subsemigroup of a regular semigroup $S$ we mean a subsemigroup $T$ of $S$ containing a least associate of each $x \in S$, in relation to the natural partial order $\leq_S$ in $S$. In this paper we investigate a class of orthodox monoids with an associate inverse subsemigroup and obtain a known description of uniquely unit regular orthodox semigroups as a corollary. Also, by considering a more general situation, we identify the homomorphic image of a kind of semidirect product of a band with identity by an inverse monoid, thus extending a known result for unit regular orthodox semigroups.Portuguese Foundation for Science and Technology (FCT) through the Research Centre CMA

Mead production: Fermentative performance of yeasts entrapped in different concentrations of alginate

Mead is an alcoholic drink known since ancient times, produced by yeast fermenting diluted honey. However, the production of mead has suffered in recent years, partially owing to the lack of scientific progress in this field. In this study, two strains of Saccharomyces cerevisiae, QA23 and ICVD47, were immobilized in 2 or 4% (w/v) alginate beads to assess the most effective alginate concentration for yeast immobilization to produce mead. Neither of the alginate concentrations was able to prevent cell leakage from the beads. The fermentation length was 120h for both yeast strains. In all cases, at the end of the fermentation, the number of cells entrapped in the beads was higher than the number of free cells, and the total 4% alginate bead wet weight was significantly higher than the 2% alginate bead wet weight. In addition, the evaluation of mead quality showed that the yeast strain had significantly more influence on the physicochemical characteristics than the alginate concentration. Although the yeasts immobilized in the two alginate concentrations were able to perform the fermentation, further research is needed in order to understand the evolution of the yeast population inside the beads throughout the fermentative process.The research presented in this paper was partially funded by the Fundação para a Ciência e Tecnologia, and by the PTDC project (contract PTDC/AGR-ALI/68284/2006). A.P.P. is the recipient of a PhD grant from FCT (SFRH/BD/45820/2008).info:eu-repo/semantics/publishedVersio

Cellular nanotechnology : making biological interfaces smarter

Recently, there has been an outburst of research on engineered cell–material interfaces driven by nanotechnology and its tools and techniques. This tutorial review begins by providing a brief introduction to nanostructured materials, followed by an overview of the wealth of nanoscale fabrication and analysis tools available for their development. This background serves as the basis for a discussion of early breakthroughs and recent key developments in the endeavour to develop nanostructured materials as smart interfaces for fundamental cellular studies, tissue engineering and regenerative medicine. The review covers three major aspects of nanostructured interfaces – nanotopographical control, dynamic behaviour and intracellular manipulation and sensing – where efforts are continuously being made to further understand cell function and provide new ways to control cell behaviour. A critical reflection of the current status and future challenges are discussed as a conclusion to the review

Bio-nanopatterning of Surfaces

Bio-nanopatterning of surfaces is a very active interdisciplinary field of research at the interface between biotechnology and nanotechnology. Precise patterning of biomolecules on surfaces with nanometre resolution has great potential in many medical and biological applications ranging from molecular diagnostics to advanced platforms for fundamental studies of molecular and cell biology. Bio-nanopatterning technology has advanced at a rapid pace in the last few years with a variety of patterning methodologies being developed for immobilising biomolecules such as DNA, peptides, proteins and viruses at the nanoscale on a broad range of substrates. In this review, the status of research and development are described, with particular focus on the recent advances on the use of nanolithographic techniques as tools for biomolecule immobilisation at the nanoscale. Present strengths and weaknesses, as well future challenges on the different nanolithographic bio-nanopatterning approaches are discussed

Preliminary evaluation of decolourisation of procion and everdirect dyes by yeasts

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