Scaling law in Saddle-node bifurcations for one-dimensional maps: A complex variable approach

The study of transient dynamical phenomena near bifurcation thresholds has attracted the interest of many researchers due to the relevance of bifurcations in different physical or biological systems. In the context of saddle-node bifurcations, where two or more fixed points collide annihilating each other, it is known that the dynamics can suffer the so-called delayed transition. This phenomenon emerges when the system spends a lot of time before reaching the remaining stable equilibrium, found after the bifurcation, because of the presence of a saddle-remnant in phase space. Some works have analytically tackled this phenomenon, especially in time-continuous dynamical systems, showing that the time delay, tau, scales according to an inverse square-root power law, tau similar to (mu-mu (c) )(-1/2), as the bifurcation parameter mu, is driven further away from its critical value, mu (c) . In this work, we first characterize analytically this scaling law using complex variable techniques for a family of one-dimensional maps, called the normal form for the saddle-node bifurcation. We then apply our general analytic results to a single-species ecological model with harvesting given by a unimodal map, characterizing the delayed transition and the scaling law arising due to the constant of harvesting. For both analyzed systems, we show that the numerical results are in perfect agreement with the analytical solutions we are providing. The procedure presented in this work can be used to characterize the scaling laws of one-dimensional discrete dynamical systems with saddle-node bifurcations.

Quantitative description of the self-assembly of patchy particles into chains and rings

We numerically study a simple fluid composed of particles having a hard-core repulsion complemented by two patchy attractive sites on the particle poles. An appropriate choice of the patch angular width allows for the formation of ring structures which, at low temperatures and low densities, compete with the growth of linear aggregates. The simplicity of the model makes it possible to compare simulation results and theoretical predictions based on the Wertheim perturbation theory, specialized to the case in which ring formation is allowed. Such a comparison offers a unique framework for establishing the quality of the analytic predictions. We find that the Wertheim theory describes remarkably well the simulation results.

A gest��o dos res��duos hospitalares e o papel da autoridade de sa��de : caso do concelho da Amad

RESUMO O Problema. A natureza, diversidade e perigosidade dos res��duos hospitalares (RH) exige procedimentos espec��ficos na sua gest��o. A sua produ����o depende do n��mero de unidades de presta����o de cuidados de sa��de (upcs), tipo de cuidados prestados, n��mero de doentes observados, pr��ticas dos profissionais e dos ��rg��os de gest��o das upcs, inova����o tecnol��gica, entre outros. A gest��o integrada de RH tem evolu��do qualitativamente nos ��ltimos anos. Existe uma car��ncia de informa����o sobre os quantitativos de RH produzidos nas upcs e na presta����o de cuidados domicili��rios, em Portugal. Por outro lado, os Servi��os de Sa��de P��blica, abrangendo o poder de Autoridade de Sa��de, interv��m na gest��o do risco para a sa��de e o ambiente associado �� produ����o de RH, necessitando de indicadores para a sua monitoriza����o. O quadro legal de um pa��s nesta mat��ria estabelece a estrat��gia de gest��o destes res��duos, a qual �� condicionada pela classifica����o e defini����o de RH por si adoptadas. Objectivos e Metodologias. O presente estudo pretende: quantificar a produ����o de RH resultantes da presta����o de cuidados de sa��de, em seres humanos e animais nas upcs, do sistema p��blico e privado, desenvolvendo um estudo longitudinal, onde se quantifica esta produ����o nos Hospitais, Centros de Sa��de, Cl��nicas M��dicas e Dent��rias, Lares para Idosos, Postos M��dicos de Empresas, Centros de Hemodi��lise e Cl��nicas Veterin��rias do Concelho da Amadora, e se compara esta produ����o em dois anos consecutivos; analisar as consequ��ncias do exerc��cio do poder de Autoridade de Sa��de na gest��o integrada de RH pelas upcs; quantificar a produ����o m��dia de RH, por acto prestado, nos cuidados domicili��rios e, com um estudo anal��tico transversal, relacionar essa produ����o m��dia com as caracter��sticas dos doentes e dos tratamentos efectuados; proceder �� an��lise comparativa das defini����es e classifica����es de RH em pa��ses da Uni��o Europeia, atrav��s de um estudo de revis��o da legisla����o nesta mat��ria em quatro pa��ses, incluindo Portugal. Resultados e Conclus��es. Obt��m-se a produ����o m��dia de RH, por Grupos I+II, III e IV: nos Hospitais, por cama.dia, considerando a taxa de ocupa����o; por consulta, nos Centros de Sa��de, Cl��nicas M��dicas e Dent��rias e Postos M��dicos de Empresas; por cama.ano, nos Lares para Idosos, considerando a sua taxa de ocupa����o; e por ano, nas Cl��nicas de Hemodi��lise e Veterin��rias. Verifica-se que a actua����o da Autoridade de Sa��de, produz nas upcs uma diferen��a estatisticamente significativa no aumento das contratualiza����es destas com os operadores de tratamento de RH. Quantifica-se o peso m��dio de res��duos dos Grupos III e IV produzido por acto prestado nos tratamentos domicili��rios e relaciona-se esta vari��vel dependente com as caracter��sticas dos doentes e dos tratamentos efectuados. Comparam-se os distintos crit��rios utilizados na elabora����o das defini����es e classifica����es destes res��duos inscritas na legisla����o da Alemanha, Reino Unido, Espanha e Portugal. Recomenda����es. Apresentam-se linhas de investiga����o futura e prop��e-se uma reflex��o sobre eventuais altera����es de aspectos espec��ficos no quadro legal portugu��s e nos planos de gest��o integrada de RH, em Portugal. ABSTRACT The problem: The nature, diversity and hazardousness of hospital wastes (HW) requires specific procedures in its management. Its production depends on the number and patterns of healthcare services, number of patients, professional and administration practices and technologic innovations, among others. Integrated management of HW has been developping, in the scope of quality, for the past few years. There is a lack of information about the amount of HW produced in healthcare units and in the domiciliary visits, in Portugal. On the other hand, the Public Health Services, embracing the Health Authority���s power, play a very important role in managing the risk of HW production to public and environmental health. They need to use some indicators in its monitorization. In a country, rules and regulations define hospital waste management policies, which are confined by the addopted classification and definition of HW. Goals and Methods: This research study aims to quantify the production of HW as a result of healthcare services in human beings and animals, public service and private one. Through a longitudinal study, this production is quantified in Hospitals, Health Centers, Medical and Dental Clinics, Residential Centers for old people, Companies Medical Centers and Veterinary and Haemodyalisis Clinics in Amadora���s Council, comparing this production in two consecutive years. This study also focus the consequences of the Health Authority���s role in the healthcare services integrated management of HW. The middle production of HW in the domiciliary treatments is also quantified and, with a transversal analytic study, its association with patients and treatments��� characteristics is enhanced. Finally, the definitions and classifications in the European Union Countries are compared through a study that revises this matter���s legislation in four countries, including Portugal. Results and Conclusions: We get the middle production of Groups I+II, III and IV: HW: in Hospitals, by bed.day, bearing the occupation rate; by consultation, in Health Centers, Medical and Dental Clinics and Companies Medical Centers; by bed.year in Residential Centers for old people, considering their occupation rate; by year, in Veterinary and Haemodyalisis Clinics. We verify that the Health Authority���s role produces a significative statistical difference in the rise of the contracts between healthcare services and HW operators. We quantify the Groups III and IV���s wastes middle weight, produced by each medical treatment in domiciliary visits and relate this dependent variable with patients and treatments��� characteristics. We compare the different criteria used in the making of definitions and classifications of these wastes registered in German, United Kingdom, Spain and Portugal���s laws. Recommendations: Lines of further investigation are explaned. We also tender a reflexion about potential changes in rules, in regulations and in the integrated plans for managing hospital wastes in Portugal. R��SUM�� Le Probl��me. La gestion des d��chets d'activit��s hospitali��res (DAH) et de soins de sant�� (DSS) exige des proc��dures sp��cifiques en raison de leur nature, diversit�� et dangerosit��. Leur production d��pend, parmi d���autres, du nombre d���unit��s de soins de sant�� (USS), du type de soins administr��s, du nombre de malades observ��s, des pratiques des professionnels et des organes de gestion des USS, de l���innovation technologique. La gestion int��gr��e des DAH et des DSS subit une ��volution qualitative dans les derni��res ann��es. Il existe un d��ficit d���information sur les quantitatifs de DAH et de DSS provenant des USS et de la prestation de soins domiciliaires, au Portugal. D���autre part les Services de Sant�� Publique, y compris le pouvoir de l���Autorit�� de Sant��, qui interviennent dans la gestion du risque pour la sant�� et pour l���environnement associ�� �� la production de DAH et de DSS, ont besoin d���indicateurs pour leur surveillance. Dans cette mati��re le cadre l��gal ��tablit la strat��gie de gestion de ces d��chets, laquelle est conditionn��e par la classification et par la d��finition des DAH et des DSS adopt��es par le pays. Objectifs et M��thodologie. Cet ��tude pr��tend: quantifier la production de DAH et de DSS provenant de la prestation de soins de sant��, en ��tres humains et animaux dans les USS du syst��me public et priv��. �� travers un ��tude longitudinal, on quantifie cette production dans les H��pitaux, Centres de Sant��, Cliniques M��dicales et Dentaires, Maisons de Repos pour personnes ��g��es, Cabinets M��dicaux d��� Entreprises, Centres d���H��modialyse et Cliniques V��t��rinaires du municipe d��� Amadora, en comparant cette production en deux ans cons��cutifs; analyser les cons��quences de l���exercice du pouvoir de l���Autorit�� de Sant�� dans la gestion int��gr��e des DAH et des DSS par les USS; quantifier la production moyenne de DAH et de DSS dans la prestation de soins domiciliaires et, avec un ��tude analytique transversal, rapporter cette production moyenne avec les caract��ristiques des malades et des soins administr��s; proc��der �� l��� analyse comparative des d��finitions et classifications des DAH et des DSS dans des pays de l���Union Europ��enne, �� travers un ��tude de r��vision de la l��gislation relative �� cette mati��re dans quatre pays, Portugal y compris. R��sultats et Conclusions. On obtient la production moyenne de DAH et des DSS, par Classes I+II, III et IV: dans les h��pitaux, par lit.jour, en consid��rant le taux d���occupation; par consultation, dans les Centres de Sant��, Cliniques M��dicales et Dentaires et Cabinets M��dicaux d��� Entreprises par lit.an dans les Maisons de Repos pour personnes ��g��es en consid��rant le taux d���occupation; et par an, dans les Cliniques d���H��modialyse et V��t��rinaires. On constate que l���actuation de l���Autorit�� de Sant�� produit dans les USS une diff��rence statistiquement significative dans l���accroissement de leurs contractualisations avec les op��rateurs de traitement de DAH et de DSS. On quantifie le poids moyen des d��chets des Classes III et IV produit par acte de prestation de soins �� domicile et on rapporte cette variable d��pendante avec les caract��ristiques des malades et des soins administr��s. On compare les diff��rents crit��res utilis��s dans l�����laboration des d��finitions et des classifications de ces d��chets inscrites dans la l��gis

Rede de mobilidade sustent��vel de Beja: viabilidade de implementa����o de um sistema de bicicletas el��tricas

Trabalho Final de Mestrado para obten����o do grau de Mestre em Engenharia Civil

Sero-epidemiologia de la toxoplasmosis en dos comunidades de Rwanda (Africa Central)

Se ha estudiado la preval��ncia de anticuerpos antitoxoplasma en dos comunidades rurales rwandesas, utilizando sangre total desecada en papel de filtro que se proces�� por la t��cnica de Aglutinaci��n Directa. En ambas comunidades est��n afectados el 50% de los adultos. La adquisici��n de los anticuerpos se hace tardiamente en NGD (a los 14 a��os s��lo un 12% de la problaci��n muestra anticuerpos antitoxoplasma) y m��s pronto en NVU (31% de la poblaci��n estudiada tiene anticuerpos antitoxoplasma a los 14 a��os). Se destaca el posible papel que juega esta enfermedad en la patolog��a materno-fetal, y la necesidad de nuevos studios que aumenten el conocimiento de la epidemiolog��a de la toxoplasmosis y sus mecanismos de transmisi��n en Rwanda.

The Port as a ���Non Consensual��� Organisation: An IC Management Perspective

This paper addresses a gap in the literature concerning the management of Intellectual Capital (IC) in a port, which is a network of independent organizations that act together in the provision of a set of services. As far as the authors are aware, this type of empirical context has been unexplored when regarding knowledge management or IC creation/destruction. Indeed, most research in IC still focus on individual firms, despite the more recent interest placed on the analysis of macro-level units such as regions or nations. In this study, we conceptualise the port as meta-organisation, which has the generic goal of economic development, both for itself and for the region where it is located. It provides us with a unique environment due to its complexity as an ���organisation��� composed by several organisations, connected by interdependency relationships and, typically, with no formal hierarchy. Accordingly, actors��� interests are not always aligned and in some situations their individual interests can be misaligned with the collective goals of the port. Moreover, besides having their own interests, port actors also have different sources of influence and different levels of power, which can impact on the port���s Collective Intellectual Capital (CIC). Consequently, the management of the port���s CIC can be crucial in order for its goals to be met. With this paper we intend to discuss how the network coordinator (the port authority) manages those complex relations of interest and power in order to develop collaboration and mitigate conflict, thus creating collective intellectual assets or avoiding intellectual liabilities that may emerge for the whole port. The fact that we are studying complex and dynamic processes, about which there is a lack of understanding, in a complex and atypical organisation, leads us to consider the case study as an appropriate method of research. Evidence presented in this study results from preliminary interviews and also from document analysis. Findings suggest that alignment of interests and actions, at both dyadic and networking levels, is critical to develop a context of collaboration/cooperation within the port community and, accordingly, the port coordinator should make use of different types of power in order to ensure that port���s goals are achieved.

Beliefs and Conflicts in a Real World Multi-Agent System

In a real world multiagent system, where the agents are faced with partial, incomplete and intrinsically dynamic knowledge, conflicts are inevitable. Frequently, different agents have goals or beliefs that cannot hold simultaneously. Conflict resolution methodologies have to be adopted to overcome such undesirable occurrences. In this paper we investigate the application of distributed belief revision techniques as the support for conflict resolution in the analysis of the validity of the candidate beams to be produced in the CERN particle accelerators. This CERN multiagent system contains a higher hierarchy agent, the Specialist agent, which makes use of meta-knowledge (on how the con- flicting beliefs have been produced by the other agents) in order to detect which beliefs should be abandoned. Upon solving a conflict, the Specialist instructs the involved agents to revise their beliefs accordingly. Conflicts in the problem domain are mapped into conflicting beliefs of the distributed belief revision system, where they can be handled by proven formal methods. This technique builds on well established concepts and combines them in a new way to solve important problems. We find this approach generally applicable in several domains.

Algorithm-oriented design of efficient many-core architectures applied to dense matrix multiplication

Recent integrated circuit technologies have opened the possibility to design parallel architectures with hundreds of cores on a single chip. The design space of these parallel architectures is huge with many architectural options. Exploring the design space gets even more difficult if, beyond performance and area, we also consider extra metrics like performance and area efficiency, where the designer tries to design the architecture with the best performance per chip area and the best sustainable performance. In this paper we present an algorithm-oriented approach to design a many-core architecture. Instead of doing the design space exploration of the many core architecture based on the experimental execution results of a particular benchmark of algorithms, our approach is to make a formal analysis of the algorithms considering the main architectural aspects and to determine how each particular architectural aspect is related to the performance of the architecture when running an algorithm or set of algorithms. The architectural aspects considered include the number of cores, the local memory available in each core, the communication bandwidth between the many-core architecture and the external memory and the memory hierarchy. To exemplify the approach we did a theoretical analysis of a dense matrix multiplication algorithm and determined an equation that relates the number of execution cycles with the architectural parameters. Based on this equation a many-core architecture has been designed. The results obtained indicate that a 100 mm(2) integrated circuit design of the proposed architecture, using a 65 nm technology, is able to achieve 464 GFLOPs (double precision floating-point) for a memory bandwidth of 16 GB/s. This corresponds to a performance efficiency of 71 %. Considering a 45 nm technology, a 100 mm(2) chip attains 833 GFLOPs which corresponds to 84 % of peak performance These figures are better than those obtained by previous many-core architectures, except for the area efficiency which is limited by the lower memory bandwidth considered. The results achieved are also better than those of previous state-of-the-art many-cores architectures designed specifically to achieve high performance for matrix multiplication.

Activation of effector immune cells promotes tumor stochastic extinction: A homotopy analysis approach

In this article we provide homotopy solutions of a cancer nonlinear model describing the dynamics of tumor cells in interaction with healthy and effector immune cells. We apply a semi-analytic technique for solving strongly nonlinear systems ��� the Step Homotopy Analysis Method (SHAM). This algorithm, based on a modification of the standard homotopy analysis method (HAM), allows to obtain a one-parameter family of explicit series solutions. By using the homotopy solutions, we first investigate the dynamical effect of the activation of the effector immune cells in the deterministic dynamics, showing that an increased activation makes the system to enter into chaotic dynamics via a period-doubling bifurcation scenario. Then, by adding demographic stochasticity into the homotopy solutions, we show, as a difference from the deterministic dynamics, that an increased activation of the immune cells facilitates cancer clearance involving tumor cells extinction and healthy cells persistence. Our results highlight the importance of therapies activating the effector immune cells at early stages of cancer progression.

Explicit series solution for a glucose-induced electrical activity model of pancreatic beta-cells

In this work, we present the explicit series solution of a specific mathematical model from the literature, the Deng bursting model, that mimics the glucose-induced electrical activity of pancreatic beta-cells (Deng, 1993). To serve to this purpose, we use a technique developed to find analytic approximate solutions for strongly nonlinear problems. This analytical algorithm involves an auxiliary parameter which provides us with an efficient way to ensure the rapid and accurate convergence to the exact solution of the bursting model. By using the homotopy solution, we investigate the dynamical effect of a biologically meaningful bifurcation parameter rho, which increases with the glucose concentration. Our analytical results are found to be in excellent agreement with the numerical ones. This work provides an illustration of how our understanding of biophysically motivated models can be directly enhanced by the application of a newly analytic method.

On the analytical solutions of the Hindmarsh-Rose neuronal model

In this article we analytically solve the Hindmarsh-Rose model (Proc R Soc Lond B221:87-102, 1984) by means of a technique developed for strongly nonlinear problems-the step homotopy analysis method. This analytical algorithm, based on a modification of the standard homotopy analysis method, allows us to obtain a one-parameter family of explicit series solutions for the studied neuronal model. The Hindmarsh-Rose system represents a paradigmatic example of models developed to qualitatively reproduce the electrical activity of cell membranes. By using the homotopy solutions, we investigate the dynamical effect of two chosen biologically meaningful bifurcation parameters: the injected current I and the parameter r, representing the ratio of time scales between spiking (fast dynamics) and resting (slow dynamics). The auxiliary parameter involved in the analytical method provides us with an elegant way to ensure convergent series solutions of the neuronal model. Our analytical results are found to be in excellent agreement with the numerical simulations.

Visible range plasmonic effect produced by aluminium nanoparticles embedded in amorphous silicon

We present results, obtained by means of an analytic study and a numerical simulation, about the resonant condition necessary to produce a Localized Surface Plasmonic Resonance (LSPR) effect at the surface of metal nanospheres embedded in an amorphous silicon matrix. The study is based on a Lorentz dispersive model for a-Si:H permittivity and a Drude model for the metals. Considering the absorption spectra of a-Si:H, the best choice for the metal nanoparticles appears to be aluminium, indium or magnesium. No difference has been observed when considering a-SiC:H. Finite-difference time-domain (FDTD) simulation of an Al nanosphere embedded into an amorphous silicon matrix shows an increased scattering radius and the presence of LSPR induced by the metal/semiconductor interaction under green light (560 nm) illumination. Further results include the effect of the nanoparticles shape (nano-ellipsoids) in controlling the wavelength suitable to produce LSPR. It has been shown that is possible to produce LSPR in the red part of the visible spectrum (the most critical for a-Si:H solar cells applications in terms of light absorption enhancement) with aluminium nano-ellipsoids. As an additional results we may conclude that the double Lorentz-Lorenz model for the optical functions of a-Si:H is numerically stable in 3D simulations and can be used safely in the FDTD algorithm. A further simulation study is directed to determine an optimal spatial distribution of Al nanoparticles, with variable shapes, capable to enhance light absorption in the red part of the visible spectrum, exploiting light trapping and plasmonic effects. �� 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Influ��ncia da teoria da ag��ncia na estrutura de capital na ind��stria do cal��ado

apresentado ao Instituto de Contabilidade e Administra����o do Porto para a Disserta����o de Mestrado para obten����o do grau de Mestre em Contabilidade e Finan��as sob orienta����o do Mestre Adalmiro ��lvaro Malheiro de Castro Andrade Pereira

Multicriteria decision making: a case study in the automobile industry

Multi-criteria decision analysis(MCDA) has been one of the fastest-growing areas of operations research during the last decades. The academic attention devoted to MCDA motivated the development of a great variety of approaches and methods within the field. These methods distinguish themselves in terms of procedures, theoretical assumptions and type of decision addressed. This diversity poses challenges to the process of selecting the most suited method for a specific real-world decision problem. In this paper we present a case study in a real-world decision problem arising in the painting sector of an automobile plant. We tackle the problem by resorting to the well-known AHP method and to the MCDA method proposed by Pereira and Fontes (2012) (MMASSI). By relying on two, rather than one, MCDA methods we expect to improve the confidence and robustness of the obtained results. The contributions of this paper are twofold: first, we intend to investigate the contrasts and similarities of the results obtained by distinct MCDA approaches (AHP and MMASSI); secondly, we expect to enrich the literature of the field with a real-world MCDA case study on a complex decision making problem since there is a paucity of applied research work addressing real decision problems faced by organizations.

Multicriteria decision making: a case study in the automobile industry

Multi-criteria decision analysis (MCDA) has been one of the fastest-growing areas of operations research during the last decades. The academic attention devoted to MCDA motivated the development of a great variety of approaches and methods within the field. These methods distinguish themselves in terms of procedures, theoretical assumptions and type of decision addressed. This diversity poses challenges to the process of selecting the most suited method for a specific real-world decision problem. In this paper we present a case study in a real-world decision problem arising in the painting sector of an automobile plant. We tackle the problem by resorting to the well-known AHP method and to the MCDA method proposed by Pereira and Fontes (2012) (MMASSI). By relying on two, rather than one, MCDA methods we expect to improve the confidence and robustness of the obtained results. The contributions of this paper are twofold: first, we intend to investigate the contrasts and similarities of the results obtained by distinct MCDA approaches (AHP and MMASSI); secondly, we expect to enrich the literature of the field with a real-world MCDA case study on a complex decision making problem since there is a paucity of applied research work addressing real decision problems faced by organizations.