Flexicurity: Core Features of Portuguese Debate

According to the OECD, Portugal is an example of a country with a very high rigidity in the labour market. At the same time, Portugal is an example of a country with a high percentage or workers with short-term contracts. These conditions have led to an ongoing public discussion concerning the nee to introduce more flexibility while maintaining work security. In this paper we analyze the current situation concerning security and rigidity in the labour market and discuss the flexicurity in the Portuguese context.flexibility; security; social protection; Portugal

Raman study of Fano interference in p-type doped silicon

As the silicon industry continues to push the limits of device dimensions, tools such as Raman spectroscopy are ideal to analyze and characterize the doped silicon channels. The effect of inter-valence band transitions on the zone center optical phonon in heavily p-type doped silicon is studied by Raman spectroscopy for a wide range of excitation wavelengths extending from the red (632.8 nm) into the ultra-violet (325 nm). The asymmetry in the one-phonon Raman lineshape is attributed to a Fano interference involving the overlap of a continuum of electronic excitations with a discrete phonon state. We identify a transition above and below the one-dimensional critical point (E = 3.4 eV) in the electronic excitation spectrum of silicon. The relationship between the anisotropic silicon band structure and the penetration depth is discussed in the context of possible device applications.Comment: 6 pages, 7 figures, pape

Label-connected graphs and the gossip problem

A graph with m edges is called label-connected if the edges can be labeled with real numbers in such a way that, for every pair (u, v) of vertices, there is a (u, v)-path with ascending labels. The minimum number of edges of a label-connected graph on n vertices equals the minimum number of calls in the gossip problem for n persons, which is known to be 2n − 4 for n ≥ 4. A polynomial characterization of label-connected graphs with n vertices and 2n − 4 edges is obtained. For a graph G, let θ(G) denote the minimum number of edges that have to be added to E(G) in order to create a graph with two edge-disjoint spanning trees. It is shown that for a graph G to be label-connected, θ(G) ≤ 2 is necessary and θ(G) ≤ 1 is sufficient. For i = 1, 2, the condition θ(G) ≤ i can be checked in polynomial time. Yet recognizing label-connected graphs is an NP-complete problem. This is established by first showing that the following problem is NP-complete: Given a graph G and two vertices u and v of G, does there exist a (u, v)-path P in G such that G−E(P) is connected

National Productive Structure and Innovative Dynamics: Finding the (Endogenous) Path to Convergence

We extend the model presented in Barro and Sala-i-Martin (1997) by allowing for two types of economies - more developed and in transition to European Union integration - to both imitate and innovate varieties of intermediate goods. Besides depending on research and development expenditures, we also allow for the stochastic nature of innovation by making it also dependent on a random component. We do this by Monte Carlo simulation, using a Box-Muller process, and solve a three differential equation model by using numerical methods. Two situations are presented: a leading economy with greater institutions and more labour than the transition economy versus a situation where an institutional advance is given to the transition economy.stochastic innovation; transition economies; growth; technology; diffusion; convergence

Service scheduling in garden maintenance

Neoturf is a Portuguese company working in the area of project, building and garden’s maintenance. Neoturf would like to have a procedure for scheduling and routing efficiently the clients from garden maintenance services. The company has two teams available during the whole year and an additional team during summer to handle all the maintenance jobs. Each team consists of two or three employees with a vehicle fully equipped with the tools that allow to carry out every kind of maintenance service. In the beginning of each year, the number and frequency of maintenance interventions to conduct during the year, on each client, are accorded. Each client is assigned to the same team and, usually, time windows are established so that visits to the client should occur only within these periods. As the Neoturf costumers’ are geographically spread over a wide region, the total distance on visiting clients is a factor that has a heavy weight on the costs of the company. Neoturf is concerned with reducing these costs, while satisfying the agreements with the clients

Job quality in Europe: the North-South divide

This paper examines the job quality in Europe. It is based on the results of the Fourth European Foundation Survey on working conditions covering different dimensions including work organisation, job content, autonomy at work, aspects of worker dignity, working time and work-life balance, working conditions and safety in the workplace. The results point to the existence of great diversity in the job quality across Europe and the north-south divide. The job quality differences are related to the variety of social and institutional contexts. The countries of Southern Europe, with their social and institutional contexts falling within the scope of the Mediterranean model, generally present indicators below the European average contrasting Nordic countries having the best job quality indicators.Job Quality, North and South European Countries, Social and Institutional Context

Warehouse Storing and Collecting of Parts

This report deals with reducing the high costs resulting from the wear and tear of the fork-lifts used to store or collect items in a warehouse. Two problems were identified and addressed separately. One concerns the way items should be stored or collected at storage locations on the shelves of one corridor. The other problem seeks for an efficient way to define which fork-lift should operate on each corridor, and the order by which the fork-lifts should visit the corridors. We give to both problems formulations that fit in the framework of combinatorial optimization

Dynamics of active polymer networks

Tese de mestrado integrado, Engenharia Biomédica e Biofísica (Biofísica Médica e Fisiologia de Sistemas) Universidade de Lisboa, Faculdade de Ciências, 2019The cytoskeleton is an active soft material, comprised and regulated by a vast number of proteins. Conferring structural stability to the cell, it also plays a relevant role in a variety of other cell processes. Its diverse behaviour has made the cytoskeleton an interesting case study in soft matter physics. In this work, we aim at explaining the distinct rheological properties through the binding and unbinding of cross-linkers. We start with the Gaussian chain model, where we compare results from our numerical simulations with those found in literature. To model the cross-link capable monomers, we first study particle aggregation, implementing a new interaction potential and investigating the role of temperature and cross-linker density in the size of aggregates. By combining the two studies, we start working towards a reticulated polymer network, first studying placement of cross-linkers in the chain and then adding steric repulsion to chain interactions. This work is a simplified approach to the study of a cross-linked polymer. Despite simple, this model sets the ground for future studies, where more system-specific interactions should be included.O citoesqueleto é um biopolímero, composto e regulado por um vasto número de proteínas. Responsável por uma variedade de processos celulares, entre os quais o movimento, divisão e crescimento celular, é no entanto na estabilidade mecânica que confere à célula que tem a sua principal função. Avanços em várias técnicas experimentais vieram mostrar um comportamento reológico complexo e diversificado, muitas vezes contrastante com os seus homólogos sintéticos. A procura por um modelo que explique as peculiaridades deste biopolímero tornou-se, nos últimos anos, um dos temas mais ativos na física da matéria condensada mole. Na base do modelo desenvolvido ao longo deste trabalho está a importância da anexação e separação das diversas cadeias poliméricas na modelação de uma resposta a estímulos externos. Esta dinâmica é promovida por uma variedade de proteínas acessórias as quais designamos de reticulações. Neste trabalho começámos por introduzir o modelo da cadeia Gaussiana, mostrando a sua equivalência com o modelo mecanicista correspondente ao uso de monómeros pontuais ligados por molas. Provou-se que o modelo computacional implementado reproduzia o comportamento de uma cadeia polimérica que foi previsto, não só neste trabalho, como na literatura. Em paralelo, estudámos a agregação de partículas, implementando um potencial de interação que visa simular as características de uma reticulação. Após a validação do potencial, investigámos o efeito da temperatura e densidade de reticulações no número de ligações formadas. Mostrámos a existência de intervalos de valores que maximizam esta quantidade para os parâmetros do potencial escolhidos. Ao combinar os dois estudos feitos foi-nos finalmente possível iniciar a investigação ao modelo reticulado. Após comparar diferentes posicionamentos para a reticulação na cadeia, foram adicionados efeitos estéricos na forma de repulsão entre diferentes cadeias. Este trabalho corresponde à primeira abordagem de um modelo computacional para um polímero reticulado. Daqui resulta um modelo simples mas fundamentado, o qual deve ser trabalhado no futuro, com a adição de resistência à flexão das cadeias, um estudo mais pormenorizado no uso de repulsão entre cadeias e a adição de uma tensão de cisalhamento