898 research outputs found
Affective commitment to change and work-life balance: mediating factors
Organizational changes are carried-out to increase organizational performance. Nevertheless, and most importantly, they entail changes to an employee’s work experience. Organizational changes have consequences at an individual and organizational level, due to their common increase in work demands, concerns and feelings of uncertainty about one’s work life. Due to the increased permeability of the frontier between work and personal life, these consequences of organizational changes in turn have a strong relationship with employees’ work-life balance. Furthermore, given that the latter in turn has consequences on employees’ job satisfaction, commitment and performance, it is important that managers take into consideration how employees react to change, in order to more effectively manage it and obtain the desired results. In this study, we looked at the relationship between employees’ affective commitment to change and work-life balance, and the mediating role of job security, psychological contract fulfilment, emotional exhaustion and disengagement on this relationship. We asked a sample of 111 employees from different organizations, to complete a questionnaire. We found that affective commitment to change has a positive relationship with employees’ emotional exhaustion, which in turn is positively associated with work-life balance. Building on the uncertainty reduction theory, Job-Demands-Resources model and social exchange theory, our findings contribute to this body of literature by showing the importance of examining what factors are related to employees’ commitment to change and its relationship with work-life balance. For managers it serves as a light into the topic of organizational change management and its consequences
Modelling dependence between frequency and severity of insurance claims
Mestrado em Actuarial ScienceA estimação da perda individual é uma importante tarefa para calcular os preços das apólices de seguro. A abordagem padrão assume independência entre a frequência e a severidade dos sinistros, o que pode não ser uma suposição realística. Neste texto, a dependência entre números e montantes de sinistros é explorada, num contexto de Modelos Lineares Generalizados. Um modelo de severidade condicional e um modelo de Cópula são apresentados como alternativas para modelar esta dependência e posteriormente aplicados a um conjunto de dados fornecido por uma seguradora portuguesa. No final, a comparação com o cenário de independência é realizada.The estimation of the individual loss is an important task to price insurance policies. The standard approach assumes independence between claim frequency and severity, which may not be a realistic assumption. In this text, the dependence between claim counts and claim sizes is explored, in a Generalized Linear Model framework. A Conditional severity model and a Copula model are presented as alternatives to model this dependence and later applied to a data set provided by a Portuguese insurance company. At the end, the comparison with the independence scenario is carried out.info:eu-repo/semantics/publishedVersio
Oral contraceptives and systemic lupus erythematosus: what should we advise to our patients?
Oral contraceptives (OC) are the contraceptive method of choice for the majority of Western world women. Decision on giving OC to patients with Systemic Lupus Erythematosus (SLE) puts special issues and concerns. In fact, OC have been evocated as etiologic risk factors for SLE and also associated with an increased risk of flares. During periods of active disease an effective contraception is mandatory, but OC puts safety problems in this setting. On the other hand, many SLE patients will be on a low activity or remission state with much less aggressive medication for most of the time. Cumulative damage due to SLE and comorbidities such as cardiovascular disease, antiphospholipid syndrome/ antibodies also has to be considered for pregnancy and contraception decisions. Advice on the benefits and risks of OC is an important and difficult aspect of the care of women with SLE. This advice should be done based on the best evidence and always considering our particular subject and its changing risk profile. This review will focus on OC in SLE women and particularly on current evidence on safety
Casas Primeiro Program: Ten years of Housing First in Portugal
info:eu-repo/semantics/publishedVersio
Exploring graph coloring heuristics for optical networks planning
Optical networks are essential in today’s global communications, and the study of planning tools that efficiently allocate network resources is crucial to network providers. The assignment of wavelengths, alongside routing, are critical functions in all optical network planning tools. This dissertation focuses on the study of wavelength assignment algorithms based on Graph Coloring techniques.
In this dissertation, we analyse the performance of the usual Greedy heuristic, a well-known Graph Coloring heuristic applied to optical network planning, as well as the Degree of Saturation (DSATUR) and Recursive Largest First (RLF) heuristics, in several real net- work scenarios. These last two heuristics, to the best of our knowledge, have not yet been applied in the context of optical networks. Extensive simulations have been performed, using real network topologies, such as COST 239, and CONUS networks, considering a full mesh logical topology, and we conclude that DSATUR and RLF heuristics can out-perform Greedy heuristic in network scenarios where there are several network clusters interconnected by only one or two links. In these cases, the RLF and DSATUR heuristics provide less 9 and 5 wavelengths respectively than the Greedy heuristic. Despite generating fewer wavelengths, we have verified that these heuristics need a higher computing time than the Greedy heuristic. Besides these heuristics, the traditional First Fit and Most-Used heuristics were also studied, and lead to performance similar to the Greedy heuristics.As redes óticas são essenciais nas comunicações globais atuais e, o estudo de ferramentas de planeamento que utilizem eficientemente os recursos da rede são cruciais aos operadores de rede. A atribuição de comprimentos de onda, juntamente com o encaminhamento, são funções críticas em todas as ferramentas de planeamento de redes óticas. Esta dissertação foca-se no estudo de algoritmos de atribuição de comprimentos de onda baseados em técnicas de Coloração de Grafos.
Na presente dissertação analisamos o desempenho da heuríıstica Greedy, uma heurística de Coloração de Grafos tipicamente aplicada ao planeamento de redes óticas, assim como as heurísticas Degree of Saturation (DSATUR) and Recursive Largest First (RLF), em diversos cenários de redes reais. Estas duas últimas heurísticas, tanto quanto sabemos, ainda não foram aplicadas no contexto de redes óticas. Foram realizadas inúmeras simulações, utilizando topologias de redes reais, como as redes COST 239, e CONUS considerando uma topologia lógica em malha completa e concluímos que as heurísticas DSATUR e RLF podem superar a heurística Greedy em cenários de rede onde existem vários clusters de rede interligados por apenas uma ou duas ligações. Nestas redes, as heurísticas RLF e DSATUR, proporcionam menos 9 e 5 comprimentos de onda, respetivamente, do que a heurística Greedy. Apesar de gerarem menos comprimentos de onda, verificamos que estas heurísticas necessitam de um tempo de computação superior ao da heurística Greedy. Além de terem sido estudadas estas heurísticas, também foram estudadas as heurísticas tradicionais First Fit e Most-Used e concluímos que têm um desempenho semelhante à heurística Greedy
Romance Clitics and the Minimalist Program
Since Kayne's pioneering work on French clitic pronouns, two major questions have been asked with respect to the syntax of clitics: (i) what are the properties that force clitics to move differently from full DP's and regular affixes? (ii) why is it the case that clitics do not surface at the same positions crosslinguistically and within the same language? In this paper we try to provide an answer to both questions, insofar as its central aim is to account for Clitic Placement in European Portuguese vs other Romance languages, namely Spanish, Italian and French. We will try to show that the differences in Clitic Placement exhibited in these four Romance languages follow from the interaction of properties of Merge/Move and Economy principles and conditions on feature checking with the formal features of clitics and their hybrid status as X°'s/XP's (Kayne 1991, Chomsky 1994).info:eu-repo/semantics/publishedVersio
Avaliação da resposta neurogénica à ativação do recetor de estradiol acoplado à proteína G (GPER)
Estradiol is a steroid hormone that plays an important trophic and protective role in the adult brain, being essential not only to maintaining normal brain functions but also to protect the brain against neural injuries. There is an increasing number of studies that evidence the neuroprotective effect of estradiol, namely through the activation of the G protein-coupled estrogen receptor (GPER). However, it is not known if this protective effect involve a pro-neurogenic action of this receptor. Therefore, the aim of this study was to evaluate whether GPER activation triggers a neurogenic response in the subventricular zone (SVZ), a neurogenic niche. We confirmed the presence of GPER both in neural stem cell (NSC) cultures from SVZ and in the cells present in the borders of the lateral ventricles of mice brain, where SVZ is located. We analyse the effects evoked by GPER activation in vitro, using G1, the GPER specific agonist. GPER activation promoted a significant increase in the expression levels of the receptor as well as an increase of NSC differentiation into mature neurons and glial cells, assessed by the number of Ki67+/Neuronal nuclei (NeuN+) and Ki67+/Glial fibrillary acidic protein (GFAP+)- positive cells, respectively. Contrariwise, GPER activation did not increase neuroblast (Ki67+/ Doublecortin (DCX+)) or glial (Ki67+/DCX-) proliferation in vitro, in contrast estradiol significantly promoted neural cell proliferation. The in vivo analysis of GPER activation showed that G1 per se was able to increase neural proliferation in the mice SVZ. Taken together, the results showed that GPER activation effectively promote neurogenesis in the SVZ and has potential to be used as a neurogenic therapeutic agent.O estradiol pertence ao grupo das hormonas esteroides e desempenha um papel importante, sendo essencial não só na manutenção das funções normais do cérebro, mas também na proteção contra lesões neurais. São cada vez mais os estudos que evidenciam o efeito neuroprotetor do estradiol, nomeadamente através da ativação do recetor de estrogénio acoplado à proteína G (GPER). No entanto, não se sabe se esses efeitos neuroprotetores envolvem uma ação pró-neurogénica deste recetor. Assim, o objetivo deste estudo foi avaliar se a ativação do GPER é capaz de desencadear uma resposta neurogénica na região subventricular (SVZ). Foi confirmada a presença do GPER em culturas de células estaminais neurais (NSC) isoladas a partir da SVZ, assim como em fatias de SVZ obtidas de murganhos. A estimulação de culturas de NSC derivadas de SVZ com agonistas do GPER (G1) desencadeou um aumento significativo dos níveis de expressão do recetor bem como um aumento da diferenciação de NSC em neurónios e células da glia, avaliadas através do número de células positivas para Ki67+/ Neuronal nuclei (NeuN+) e Ki67+/ Glial fibrillary acidic protein (GFAP+), respetivamente. Pelo contrário, a ativação seletiva do GPER não aumentou o número de neuroblastos (Ki67+/ Doublecortin (DCX+)) ou células da glia (Ki67+/DCX-) proliferativos, diferindo do efeito mediado pelo estradiol, o qual aumentou significativamente a proliferação de células neurais. A injeção subcutânea de murganhos com G1 (190µg/Kg) e intraperitoneal com Bromodeoxiuridina (BrdU) mostrou que o G1, per se, aumenta a proliferação neural na SVZ de murganhos. Em conjunto, os nossos resultados sugerem que a ativação do GPER promove a neurogénese na SVZ, apresentando elevado potencial para ser utilizado como uma estratégia regeneradora
Iron storage and regulation at a molecular level
Iron is an essential element for the proper functioning of the metabolic network in a
living system. However, it is also toxic in physiological conditions. Apart from precipitation it can
damage and compromise cellular macromolecules by Fenton reactions. Thus, ferritins, hollow
spherical proteins, comes to solve this problem by storing iron in its inner cavity. Dps (DNAbinding
protein in starved cells), focused in this study, has a detoxifying function, protecting
DNA from ROS.
The reaction catalyzed by ferritins can be divided in the following stages: iron intake,
oxidation, storage and release. The latter is the least explored and known function of this
protein.
The M. hydrocarbonoclasticus WrbA flavoprotein, present in the same genome, was
used as a P. nauticas Dps redox partner, to reduced and release iron from the iron core.
Mössbauer spectroscopy was used to investigate the kinetics properties of
WrbA(FMN):NADH:Dps in anaerobic conditions. To determine kinetic parameters it was needed
to acquire spectra for different reaction times. The iron release for wild-type, Q14E and Δ15 Dps
variants follow a first-order kinetic, with rate constants very similar.
Was also explored a more inexpensive and faster kinetic assay based on the ophenanthroline
method, monitored by Visible spectroscopy. The result showed that the three
Dps variants have no significant difference regarding the kinetic profile obtained, but rate
constants were significantly lower than those obtained by Mössbauer spectroscopy probed
kinetic measurements. Phenanthroline might cause an inhibitor effect and in order to
understand that effect, the kinetic assays were repeated in the absence of phenanthroline.
Using bioinformatic tools (docking, modeling and others), was possible to conclude that
exist conserved amino acid (G43, L74, P78 e W149) in Dps that appear to participate and are in
the electron transfer pathway
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