Two-ballot versus plurality rule: an empirical investigation on the number of candidates

Duverger claimed more than 50 years ago that the number of candidates in elections should be a function of electoral rules. Both his “law” and “hypothesis” suggest the number of candidates vying for seats in elections to be tightly linked to characteristics of the electoral process such as its degree of proportionality and the presence of runoffs. Here we test the validity of Duverger’s claim using data from municipal elections in Brazil. Our study differs from others in the field in two important dimensions. First, by using municipal data we avoid the usual problems that plague statistical analysis using cross-country data. Secondly, we have a truly exogenous source of variation due to a change in electoral legislation introduced by the constitutional reform of 1988: simple plurality remained the rule only in municipalities with less than 200,000 voters, and a second-ballot became mandatory for the others above that threshold. This allows for a neat identification strategy using panel data. Our main finding is that elections with runoffs lure greater numbers of candidates in municipalities with sufficiently high levels of heterogeneity.Duverger's law, runoff, heterogeneity

Improved isolation of murine hepatocytes for in vitro malaria liver stage studies

<p>Abstract</p> <p>Background</p> <p>Primary hepatocyte cultures are a valuable tool for the understanding of cellular and molecular phenomena occurring during malaria liver stage. This paper describes an improved perfusion/dissociation procedure to isolate hepatocytes from mouse liver that is suitable for malaria studies and allows reproducible preparation of primary hepatocytes with consistent cell yields and controlled purity.</p> <p>Results</p> <p>This protocol is a detailed description of a technique to isolate and culture mouse hepatocytes and represents an improvement over previous descriptions of hepatocyte isolation for malaria studies, regarding three technical aspects: (1) dissociation reagents choice; (2) cell separation gradient and (3) cell purity control. Cell dissociation was optimized for a specific collagenase digestion media. The cell dissociation step was improved by using a three-layer discontinuous gradient. A cell purity check was introduced to monitor the expression of CD95 on hepatocytes using flow cytometry methods.</p> <p>Conclusion</p> <p>The procedure described allows reproducible recovery of one to three million hepatocytes per preparation with cell purity of about 90% as determined by FACS analysis. Completion of the protocol is usually achieved in about four hours per preparation and pooling is suggested for multiple preparations of larger number of cells.</p

Study of tribological properties of moulds obtained by stereolithography

Stereolithography (SL) is a process that allows the rapid manufacturing of high-accuracy rapid tools using an ultraviolet laser beam to polymerize a liquid resin, layer-by-layer. In this work, the friction properties of commercial SL resins in contact with several thermoplastics were assessed. Friction experiments were done with plastics overmoulded onto moulding blocks made from SL resins. It was observed that polymers with Hildebrand solubility parameters close to the resins showed adhesion characteristics that were not observed in polymers with values of this parameter further apart.EU Programme ALFA (project Plastinet-master

Netnography: Origins, Foundations, Evolution and Axiological and Methodological Developments and Trends

Netnography originated in ethnography and evolved following the advances in data transmission technology. The netnographic method is distinguished by its axiological orientation residing in recognition of online social experiences. The main method for data collection adopted by the netnographer is participant observation. One premise that must be observed is the necessary estrangement, which means that the researcher must be a layman as regards the object of study. In the field of administration, netnography emphasized the area of marketing and consumer behavior. The goal is to understand the consumer culture of online communities. One of its main challenges consists of how to conduct ethical research. The current article reviewed the available literature about the netnography method, bringing a brief explanation about its emergence and evolution, as well as its characteristics and application. The article also presents the advantages, challenges, and trends of this modern research method and also suggests topics for future research

Cobertura pré-fabricada em betão auto-compactável reforçado com fibras de aço

O presente trabalho refere-se ao estudo de uma cobertura realizada com elementos pré-fabricados em Betão Auto-Compactável Reforçado com Fibras de Aço (BACRFA). A cobertura em análise, com uma área de implantação de 9.8 x 5.5 m2, é constituída por peças com secção em “T”, justapostas, suportadas por vigas pré-esforçadas realizadas em BACRFA, sem qualquer tipo de armadura convencional passiva. Neste sentido, a armadura longitudinal é constituída apenas por varões pré-tensionados e o reforço ao corte é garantido pelas fibras discretas em aço que reforçam o betão auto-compactável. Os ensaios experimentais, realizados com modelos à escala real das vigas T, foram executados com o intuito de avaliar a deformação a longo prazo e a capacidade de carga das peças da cobertura, sujeitando-as a diferentes condições de carregamento. Em simultâneo foi desenvolvido em laboratório, um BACRFA com propriedades adequadas aos esforços que se desenvolvem neste tipo de estrutura e à geometria dos elementos que a compõem. Em comparação com a solução tradicional em betão armado, a que se propõem apresenta vantagens resultantes da diminuição do tempo de execução, da melhoria da durabilidade e da aparência

Three-Dimensional CFD modelling and analysis of the thermal entrainment in open refrigerated display cabinets

This study presents a three-dimensional Computational Fluid Dynamics (CFD) simulation of the air flow pattern and the temperature distribution in a refrigerated display cabinet. The thermal entrainment is evaluated by the variations of the mass flow rate and thermal power along and across the air curtain considering the numerical predictions of abovementioned properties. The evaluation on the ambient air velocity for the three-dimensional (3D) effects in the pattern of this type of turbulent air flow is obtained. Additionally, it is verified that the longitudinal air flow oscillations and the length extremity effects have a considerable influence in the overall thermal performance of the equipment. The non uniform distribution of the air temperature and velocity throughout the re-circulated air curtain determine the temperature differences in the linear display space and inside the food products, affecting the refrigeration power of display cabinets. The numerical predictions have been validated by comparison with experimental tests performed in accordance with the climatic class n.º 3 of EN 441 Standard (Tamb = 25 ºC,φamb = 60%; vamb = 0,2 m s-1). These tests were conducted using the point measuring technique for the air temperature, air relative humidity and air velocity throughout the air curtain, the display area of conservation of food products and nearby the inlets/outlets of the air mass flow.info:eu-repo/semantics/publishedVersio

Detailed CFD modelling of open refrigerated display cabinets

A comprehensive and detailed computational fluid dynamics (CFDs) modelling of air flow and heat transfer in an open refrigerated display cabinet (ORDC) is performed in this study. The physical-mathematical model considers the flow through the internal ducts, across fans and evaporator, and includes the thermal response of food products. The air humidity effect and thermal radiation heat transfer between surfaces are taken into account. Experimental tests were performed to characterize the phenomena near physical extremities and to validate the numerical predictions of air temperature, relative humidity, and velocity. Numerical and experimental results comparison reveals the predictive capabilities of the computational model for the optimized conception and development of this type of equipments. Numerical predictions are used to propose geometrical and functional parametric studies that improve thermal performance of the ORDC and consequently food safety.info:eu-repo/semantics/publishedVersio

Experimental analysis of the thermal entrainment three dimensional effects in re-circulated air curtains

The application of air curtains devices to HVAC&R systems have been developed in order to improve the thermal and mass separation between two contiguous spaces with differentiated air behaviours. The refrigeration equipments installed inside commercial spaces and open to the surroundings suffer alterations of their thermal behaviours and energy efficiency due to variations in magnitude and orientation of the air velocity. The location of the air conditioning system discharge grilles, the mass flows rates originated by pressure differences due to openings to the external environment and the air flow perturbation due to the circulation of the consumers nearby the opening of the display cases, among others, affect the re-circulated air curtain behaviour and the overall performance of the equipment.This study presents the experimental results obtained from tests carried out for the climatic class n.º 3 of EN 441 (Tamb = 25 ºC, φamb = 60%; vamb = 0,2 m/s) and the analysis of the threedimensional effects observed in the thermal interaction through the air curtains installed in open vertical refrigerated display cases. The obtained results are related to the air temperature, air relative humidity and air velocity measurements fields throughout the air curtain. From the analysis of the obtained results some comparable effects in the fields of the same properties for the display space of the exposition and conservation of food products and nearby the inlets/outlets of the air mass flow, can be sorted out. The evaluation of the ambient air velocity three-dimensional effects in the pattern of this type of turbulent air flow is obtained. Additionally, it is verified that the longitudinal airflow fluctuations and the length extremity effects of the display case have a considerable influence in the overall thermal performance of the equipment. The non-uniform distribution of the air temperature, relative humidity and velocity throughout the air curtain determines temperature differences in the linear dimension display space and inside the food products, affecting the correct behaviour of the display cases. Besides that, this study helps to show some of the fragilities of the numerical models bi-dimensional formulation.info:eu-repo/semantics/publishedVersio

Extending the Synoptics of Things (SoT) Framework to Manage ISoS Technology Landscapes

Managing and monitoring the software and hardware artifacts of an industrial organization are fundamental efforts that can often be challenging endeavors to achieve, especially when such technological landscapes are composed of multiple heterogeneous systems. Usually, Internet of Things (IoT) devices are provided by different suppliers and may use different protocols and interfaces. Thus, the integration of these devices results in complex development and maintenance cycles. The Synoptics of Things (SoT) framework can address these problems, in conjunction with the Informatics System of Systems (ISoS) platform by promoting an open market competitive tech nology landscape for organizations. The purpose of the research presented in this paper was to extend the SoT framework in order to manage and monitor the different elements of an ISoS enabled organization, namely the ISystems (Informatics Systems), CES (Cooperation Enabled Services), and Services. We argue that the SoT framework can be essential in a supervisory control and data acquisition (SCADA) system in today’s modern web, by adopting the concept of Web Components as a standard to enable the development of custom and reusable components. We present and discuss such issues in the context of the HORUS system, an informatic system responsible for payment enforcement in fueling stations. In this system, several devices must work in coordination, such as video cameras and video recorders, which are fundamental for the retrieving of license plate images and, therefore, be continually monitored to ensure the correct functioning of the HORUS system.info:eu-repo/semantics/publishedVersio