Eficiência e concentração na indústria bancária

O objectivo deste trabalho é a análise da eficiência produtiva e dos efeitos da concentração sobre os custos bancários, tendo por base a indústria bancária portuguesa. O carácter multiproduto da empresa bancária sugere a necessidade de se adoptar formas multiproduto da função custo (tipo Fourier). Introduzimos variáveis de homogeneidade e de estrutura que permitem o recurso a formas funcionais uniproduto (Cobb-Douglas) à banca. A amostra corresponde a 22 bancos que operavam em Portugal entre 1995-2001, base não consolidada e dados em painel. Para o estudo da ineficiência recorreu-se ao modelo estocástico da curva fronteira (SFA), para as duas especificações. Na análise da concentração, introduziram-se variáveis binárias que pretendem captar os efeitos durante quatro anos após a concentração. Tanto no caso da SFA como no da concentração, os resultados encontrados são sensíveis à especificação funcional adoptada. Concluindo, o processo de concentração bancário parece justificar-se pela possibilidade da diminuição da ineficiência-X. This study addresses the productive efficiency and the effects of concentration over the banking costs, stressing its focus on the Portuguese banking market. The multiproduct character of the banking firm suggests the use of functional forms as Fourier. The introduction of variables of structure and of homogeneity allows the association of the banking activity (multiproduct) with a single product function (Cobb-Douglas type). The sample covers 22 banks which operated in Portugal from 1995-2001, non consolidated base with a panel data structure. The study about inefficiency is elaborated through the stochastic frontier model (SFA), for the two specifications selected. As a methodology to analyze the concentration, we introduced binary variables, which intend to catch the effects through four years after the concentration process. The results obtained, through SFA and concentration approach, are influenced by the kind of specifications selected. Summing up, the concentration process of the Banking Industry sounds to be justified by the possibility of the X-inefficiency.

Avaliação do stress oxidativo na disfunção erétil

As sequelas fisiopatológicas do stress oxidativo são difíceis de quantificar. Apesar dos obstáculos, a relevância médica do stress oxidativo tem vindo a ser cada vez mais reconhecida, sendo hoje em dia encarado como um componente chave de virtualmente todas as doenças. A disfunção erétil (DE) surge neste contexto como uma espécie de barómetro da função endotelial e do dano oxidativo. A quantificação de biomarcadores de stress oxidativo poderá apresentar um enorme impacto na avaliação de pacientes com DE. O rácio glutationa reduzida/oxidada (GSH/GSSG) e a nitrotirosina (3-NT) têm vindo a demonstrar relevância clínica. A consideração de polimorfismos genéticos constitui ainda uma abordagem promissora na avaliação destas relações no futuro. Um método altamente sensível de cromatografia líquida de alta performance (HPLC) foi desenvolvido para a determinação de 3-NT em plasma humano. As concentrações de 3-NT medidos em indivíduos com DE foram 6,6±2,1μM (média±S.D., n = 46). A medição da concentração plasmática de 3-NT poderá revelar-se útil como marcador de dano oxidativo dependente do óxido nítrico (NO). O nível de stress oxidativo pode também ser quantificado através da medição do decréscimo do rácio GSH/GSSG, que tem mostrado alterações numa miríade de patologias, como a DE e a diabetes mellitus. O método proposto para a quantificação do rácio GSH/GSSG em HPLC apresenta a vantagem de avaliação concomitante dos dois parâmetros em apenas uma corrida. O valor do rácio GSH/GSSG obtido a partir de sangue de indivíduos com DE foi 11,9±9,8 (média±S.D., n = 49). Os resultados estatísticos revelaram diferenças significativas (p<0,001) entre ambos a concentração plasmática de 3-NT e o rácio GSH/GSSG de sangue de indivíduos com DE e as respetivas medições em indivíduos saudáveis. Observaram-se ainda diferenças estatisticamente significativas (p≈0,027) entre o rácio GSH/GSSG do sangue de pacientes apenas com diagnóstico de DE e a medição respetiva em indivíduos com DE e comorbilidades cardiovasculares. Estes resultados enfatizam o papel do dano oxidativo na biopatologia da DE, elucidado com o auxílio destas duas metodologias, que poderão ter um amplo campo de aplicação no futuro, dado que se mostraram simples, não dispendiosas e rápidas, podendo eventualmente adequar-se a estudos de rastreio em larga escala.

Caracterização da função pulmonar de bombeiros da Região Norte de Portugal

Os Bombeiros estão expostos frequentemente a vários poluentes prejudicando gravemente a sua saúde respiratória. Foi realizado um estudo observacional e transversal, com o objectivo de caracterizar a função pulmonar dos bombeiros da região norte de Portugal. A amostra foi constituída por 44 Bombeiros de Valongo e Rebordosa. Todos os participantes preencheram um questionário, executaram espirometrias e mediram o monóxido de carbono. Verificou-se uma elevada prevalência de hábitos tabágicos, bem como da carga tabágica. A percentagem de alterações espirométricas foi de 38,6% e a utilização de protecção respiratória revelou-se praticamente inexistente nos incêndios florestais.

Solving MPCC problem with the hyperbolic penalty function

The main goal of this work is to solve mathematical program with complementarity constraints (MPCC) using nonlinear programming techniques (NLP). An hyperbolic penalty function is used to solve MPCC problems by including the complementarity constraints in the penalty term. This penalty function [1] is twice continuously differentiable and combines features of both exterior and interior penalty methods. A set of AMPL problems from MacMPEC [2] are tested and a comparative study is performed.

Solving a signalized traffic intersection problem with an hyperbolic penalty function

Mathematical Program with Complementarity Constraints (MPCC) finds many applications in fields such as engineering design, economic equilibrium and mathematical programming theory itself. A queueing system model resulting from a single signalized intersection regulated by pre-timed control in traffic network is considered. The model is formulated as an MPCC problem. A MATLAB implementation based on an hyperbolic penalty function is used to solve this practical problem, computing the total average waiting time of the vehicles in all queues and the green split allocation. The problem was codified in AMPL.

Oxidative Leaching of metals from electronic waste with solutions based on quaternary ammonium salts

The treatment of electric and electronic waste (WEEE) is a problem which receives ever more attention. An inadequate treatment results in harmful products ending up in the environment. This project intends to investigate the possibilities of an alternative route for recycling of metals from printed circuit boards (PCBs) obtained from rejected computers. The process is based on aqueous solutions composed of an etchant, either 0.2 M CuCl2.2H2O or 0.2 M FeCl3.6H2O, and a quaternary ammonium salt (quat) such as choline chloride or chlormequat. These solutions are reminiscent of deep eutectic solvents (DES) based on quats. DES are quite similar to ionic liquids (ILs) and are used as well as alternative solvents with a great diversity of physical properties, making them attractive for replacement of hazardous, volatile solvents (e.g. VOCs). A remarkable difference between genuine DES and ILs with the solutions used in this project is the addition of rather large quantities of water. It is shown the presence of water has a lot of advantages on the leaching of metals, while the properties typical for DES still remain. The oxidizing capacities of Cu(II) stem from the existence of a stable Cu(I) component in quat based DES and thus the leaching stems from the activity of the Cu(II)/Cu(I) redox couple. The advantage of Fe(III) in combination with DES is the fact that the Fe(III)/Fe(II) redox couple becomes reversible, which is not true in pure water. This opens perspectives for regeneration of the etching solution. In this project the leaching of copper was studied as a function of gradual increasing water content from 0 - 100w% with the same concentration of copper chloride or iron(III) chloride at room temperature and 80ºC. The solutions were also tested on real PCBs. At room temperature a maximum leaching effect for copper was obtained with 30w% choline chloride with 0.2 M CuCl2.2H2O. The leaching effect is still stronger at 80°C, b ut of course these solutions are more energy consuming. For aluminium, tin, zinc and lead, the leaching was faster at 80ºC. Iron and nickel dissolved easily at room temperature. The solutions were not able to dissolve gold, silver, rhodium and platinum.

Square-wave voltametric method for determination of molinate concentration in a biological process using a hanging mercury drop electrode

A square-wave voltammetric (SWV) method using a hanging mercury drop electrode (HMDE) has been developed for determination of the herbicide molinate in a biodegradation process. The method is based on controlled adsorptive accumulation of molinate for 10 s at a potential of -0.8 V versus AgCl/Ag. An anodic peak, due to oxidation of the adsorbed pesticide, was observed in the cyclic voltammogram at ca. -0.320 V versus AgCl/Ag; a very small cathodic peak was also detected. The SWV calibration plot was established to be linear in the range 5.0x10-6 to 9.0x10-6 mol L-1; this corresponded to a detection limit of 3.5x10-8 mol L-1. This electroanalytical method was used to monitor the decrease of molinate concentration in river waters along a biodegradation process using a bacterial mixed culture. The results achieved with this voltammetric method were compared with those obtained by use of a chromatographic method (HPLC–UV) and no significant statistical differences were observed.

Inventories and concentration profiles of 137Cs in undisturbed soils in the northeast of Buenos Aires Province, Argentina

Inventories and vertical distribution of (137)Cs were determined in La Plata region undisturbed soils, Argentina. A mean inventory value of 891 ± 220 Bq/m(2) was established, which is compatible with the values expected from atmospheric weapon tests fallout. The study was complemented with pH, organic carbon fraction, texture and mineralogical soil analyses. Putting together Southern Hemisphere (137)Cs inventory data, it is possible to correlate these data with the mean annual precipitations. The large differences in (137)Cs concentration profiles were attributed to soil properties, especially the clay content and the pH values. A convection-dispersion model with irreversible retention was used to fit the activity concentration profiles. The obtained effective diffusion coefficient and effective convection velocity parameters values were in the range from 0.2 cm(2)/y to 0.4 cm(2)/y and from 0.23 cm/y to 0.43 cm/y, respectively. These data are in agreement with values reported in literature. In general, with the growth of clay content in the soil, there was an increase in the transfer rate from free to bound state. Finally, the highest transfer rate from free to bound state was obtained for soil pH value equal to 8.

Host-Guest interaction between herbicide oxadiargyl and hydroxypropyl-β-cyclodextrin

In the face of a growing human population and increased urbanization, the demand for pesticides will simply rise. Farmers must escalate yields on increasingly fewer farm acres. However, the risks of pesticides, whether real or perceived, may force changes in the way these chemicals are used. Scientists are working toward pest control plans that are environmentally sound, effective, and profitable. In this context the development of new pesticide formulations which may improve application effectiveness, safety, handling, and storage can be pointed out as a solution. As a contribution to the area, the microencapsulation of the herbicide oxadiargyl (OXA) in (2-hydroxypropyl)-β-cyclodextrin (HP-β-CD) was performed. The study was conducted in different aqueous media (ultrapure water and in different pH buffer solutions). In all cases an increment of the oxadiargyl solubility as a function of the HP-β-CD concentration that has been related to the formation of an inclusion complex was verified. UV-Vis and NMR experiments allowed concluding that the stoichiometry of the OXA/HP-β-CD complex formed is 1 : 1. The gathered results can be regarded as an important step for its removal from industrial effluents and/or to increase the stabilizing action, encapsulation, and adsorption in water treatment plants.

Exploiting a prioritized MAC protocol to efficiently compute interpolations

Consider a network where all nodes share a single broadcast domain such as a wired broadcast network. Nodes take sensor readings but individual sensor readings are not the most important pieces of data in the system. Instead, we are interested in aggregated quantities of the sensor readings such as minimum and maximum values, the number of nodes and the median among a set of sensor readings on different nodes. In this paper we show that a prioritized medium access control (MAC) protocol may advantageously be exploited to efficiently compute aggregated quantities of sensor readings. In this context, we propose a distributed algorithm that has a very low time and message-complexity for computing certain aggregated quantities. Importantly, we show that if every sensor node knows its geographical location, then sensor data can be interpolated with our novel distributed algorithm, and the message-complexity of the algorithm is independent of the number of nodes. Such an interpolation of sensor data can be used to compute any desired function; for example the temperature gradient in a room (e.g., industrial plant) densely populated with sensor nodes, or the gas concentration gradient within a pipeline or traffic tunnel.

Penalty fuzzy function for derivative-free optimization

Penalty and Barrier methods are normally used to solve Nonlinear Optimization Problems constrained problems. The problems appear in areas such as engineering and are often characterised by the fact that involved functions (objective and constraints) are non-smooth and/or their derivatives are not know. This means that optimization methods based on derivatives cannot net used. A Java based API was implemented, including only derivative-free optimizationmethods, to solve both constrained and unconstrained problems, which includes Penalty and Barriers methods. In this work a new penalty function, based on Fuzzy Logic, is presented. This function imposes a progressive penalization to solutions that violate the constraints. This means that the function imposes a low penalization when the violation of the constraints is low and a heavy penalisation when the violation is high. The value of the penalization is not known in beforehand, it is the outcome of a fuzzy inference engine. Numerical results comparing the proposed function with two of the classic penalty/barrier functions are presented. Regarding the presented results one can conclude that the prosed penalty function besides being very robust also exhibits a very good performance.

Fitness function evaluation through fractional algorithms

This paper proposes a Genetic Algorithm (GA) for the design of combinational logic circuits. The fitness function evaluation is calculated using Fractional Calculus. This approach extends the classical fitness function by including a fractional-order dynamical evaluation. The experiments reveal superior results when comparing with the classical method.

Fractional describing function of systems with nonlinear friction

This paper studies the describing function (DF) of systems consisting in a mass subjected to nonlinear friction. The friction force is composed in three components namely, the viscous, the Coulomb and the static forces. The system dynamics is analyzed in the DF perspective revealing a fractional-order behaviour. The reliability of the DF method is evaluated through the signal harmonic content and the limit cycle prediction.