962 resultados para Buffer stock model
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This paper describes the modification of a two-dimensional finite element long wave hydrodynamic model in order to predict the net current and water levels attributable to the influences of waves. Tests examine the effects of the application of wave induced forces, including comparisons to a physical experiment. An example of a real river system is presented with comparisons to measured data, which demonstrate the importance of simulating the combined effects of tides and waves upon hydrodynamic behavior. (C) 2002 Elsevier Science Ltd. All rights reserved.
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The presence of toxic cyanobacteria in drinking water reservoirs renders the need to develop treatment methods for the 'safe' removal of their associated toxins. Chlorine has been shown to successfully remove a range of cyanotoxins including microcystins, cylindrospermopsin and saxitoxins. Each cyanotoxin requires specific treatment parameters, particularly solution pH and free chlorine residual. However, currently there has not been any investigation into the toxicological effect of solutions treated for the removal of these cyanotoxins by chlorine. Using the P53(def) transgenic mouse model mate and female C57BL/6J hybrid mice were used to investigate potential cancer inducing effects from such oral dosing solutions. Both purified cyanotoxins and toxic cell-free extract cyanobacterial solutions were chlorinated and administered over 90 and 170 days (respectively) in drinking water. No increase in cancer was found in any treatment. The parent cyanotoxins, microcystins, cylindrospermopsin and saxitoxins were readily removed by chlorine. There was no significant increase in the disinfection byproducts trihalomethanes or haloacetic acids, levels found were well below guideline values. Histological examination identified no effect of treatment solutions except male mice treated with chlorinated cylindrospermopsin (as a cell free extract). In this instance 40% of males were found to have fatty vacuolation in their livers, cause unknown. It is recommended that further toxicology be undertaken on chlorinated cyanobacterial solutions, particularly for non-genotoxic carcinogenic compounds, for example the Tg. AC transgenic mouse model. (C) 2003 Elsevier Science Ltd. All rights reserved.
Os fundos de investimento imobiliário listados em bolsa e as variáveis que influenciam seus retornos
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Os fundos de investimento imobiliário combinam características tanto do mercado imobiliário, fonte de seus rendimentos, quanto do mercado de capitais, ambiente em que são negociados. O impacto de cada um desses mercados subjacentes no comportamento, desempenho e risco dessa classe de ativos não é, no entanto, ainda claramente definida, sendo um dos grandes temas em análise, tanto na literatura acadêmica, quanto na indústria de fundos internacionais. Em face da significativa expansão dessa alternativa de investimento no mercado brasileiro, no presente estudo foram analisadas as variáveis que influenciam os retornos dos fundos imobiliários brasileiros para uma amostra de fundos listados em Bolsa de Valores de São Paulo, período de 2008-2013. Seguindo a metodologia de Clayton e Mackinnon (2003), os fatores explicativos dos retornos foram decompostos em quatro componentes principais, sendo três fatores de retorno de mercado (mercado de ações, mercado de renda fixa e mercado imobiliário) e risco idiossincrático. De acordo com a estatística descritiva, os fundos imobiliários da amostra apresentaram maior retorno em relação aos demais mercados, exceto em comparação com o mercado imobiliário, porém com menor risco. As análises de correlação, regressão e decomposição da variância indicam que o mercado de ações e o mercado imobiliário direto são, em geral, significativos no modelo, porém explicam apenas cerca de 15% da volatilidade dos retornos dos fundos da amostra. À luz da Moderna Teoria do Portfólio, esses resultados indicam que a inclusão de fundos imobiliários pode ter potencial diversificador numa carteira multi-ativo, seja aumentando o retorno total de uma carteira formada de ações e títulos de renda fixa, sem acréscimo em risco; ou mantendo o retorno dessa carteira, com diminuição da volatilidade, ampliando assim a fronteira eficiente da carteira. Esse efeito questiona o tradicional equilibrium fund de carteiras de investimentos formadas apenas de ações e renda fixa e aponta os fundos imobiliários como uma alternativa de investimento diversificadora, enquanto classe de ativo única. A análise de subamostras por tipologia indica, porém, que o papel diversificador dos fundos imobiliários está atrelado ao tipo de empreendimento que lastreia esse fundo, uma vez que os fatores explicativos e seus impactos nos retornos diferem de uma tipologia para outra. Esse resultado tem importantes implicações no critério de seleção a ser adotado tanto por investidores para seleção de ativos para uma carteira otimizada, como para gestores de fundos imobiliários na formatação e gestão desses produtos. Conclui-se também que os retornos dos fundos, de certo modo, refletem seu caráter híbrido, mas o modelo decomposto em 4 componentes não é suficiente para explicar os retornos dos fundos imobiliários, uma vez que o modelo estendido, demonstrou que outras variáveis, inclusive parâmetros desses próprios mercados, além de variáveis macroeconômicas e as características de cada fundo (eg. market-to-book, tamanho), podem ser responsáveis por explicar considerável parte da variância dos retornos dos FIIs.
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A distribuição geográfica de um táxon é limitada por aspectos ecológicos e históricos. Muitas atividades humanas têm causado modificações na cobertura vegetal, o que leva à fragmentação e perda do habitat. Isso tem levado à extinção local de populações de várias espécies, alterando sua distribuição geográfica. Entre elas estão as duas espécies do gênero Brachyteles (os muriquis), que são primatas endêmicos de um dos biomas mais afetados por esses processos, a Mata Atlântica. A União Internacional para a Conservação da Natureza (UICN) é uma organização que busca conservar a biodiversidade. Entre outros critérios, utiliza o conhecimento sobre as distribuições geográficas restritas das espécies para classificá-las em categorias de ameaça de extinção, nas chamadas listas vermelhas. Para isso, utiliza parâmetros espaciais, cujos resultados indicam o risco de extinção de determinado táxon em relação à sua distribuição geográfica. Muitas vezes os cálculos desses parâmetros são realizados de maneira subjetiva, de maneira que é importante a busca de métodos que tornem as classificações mais objetivas, precisas e replicáveis. Nesse contexto, o presente trabalho testou diferentes métodos de cálculos de três parâmetros relacionados à distribuição geográfica de B. hypoxanthus e B. arachnoides. Tratam-se de espécies ameaçadas de extinção, com localidades de ocorrência bem conhecidas, que foram profundamente afetadas pela degradação da Mata Atlântica. Assim, podem ser consideradas bons modelos para essas análises. Foi construído um banco de dados de localidades de ocorrência atuais das duas espécies. Por meio de abordagens de Sistemas de Informação Geográfica (SIG), foram estimadas a Extensão de Ocorrência (EOO) através de Mínimo Polígono Convexo e α-hull e Área de Ocupação (AOO) e Subpopulações por meio de métodos de grids, buffers circulares e α-hull, em diferentes escalas espaciais. Os resultados dos cálculos desses parâmetros foram comparados para identificar as abordagens e escalas mais adequadas para a avaliação de risco de extinção. Esses resultados indicam que as listas de localidades e os mapas de distribuição disponibilizados pela UICN precisam ser atualizados. Além disso, sugerem que α-hull é uma abordagem vantajosa para EOO e o método de buffers é mais adequado para os parâmetros de AOO e Subpopulações, quando utiliza escalas espaciais menores. Também foi utilizada a ferramenta GeoCAT, para as duas espécies. Essa ferramenta, por realizar análises de EOO e AOO instantâneas e por seus resultados serem semelhantes aos de outras análises, serve como uma abordagem preliminar de risco de extinção baseado no critério de distribuição geográfica.
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This article recommends a new way to improve Refugee Status Determination (RSD) procedures by proposing a network society communicative model based on active involvement and dialogue among all implementing partners. This model, named after proposals from Castells, Habermas, Apel, Chimni, and Betts, would be mediated by the United Nations High Commissioner for Refugees (UNHCR), whose role would be modeled after that of the International Committee of the Red Cross (ICRC) practice.
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This paper analyzes People's Republic of China (PRC) economic and political ascendance in the 21st century focusing on the evolution of the sui generis economic development model and its significances of the evolution of relationship between China and the developing countries in the peripheral "Global South." The objective of this article is to analyze the relationship between China and the Global South (Africa and South America) in the 21st century, characterized as a new Center-periphery global network power based on trade and investment that we call as "Asian Consensus."
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The historic center of the Portuguese city of Guimarães is a world heritage site (UNESCO) since 2001, having hosted the European Capital of Culture (ECOC) in 2012. In this sense, Guimarães has made a major effort in promoting tourism, positioning itself as an urban and cultural tourism destination. The present paper has two objectives. The first, to examine if an existing push and pull motivation model finds statistical support with regard to the population of the municipality of Guimarães, a cultural tourism destination. The second, to study the role that important socio-demographic variables, such as gender, age, and education, play in determining travel motivations of residents from this municipality. Insight on tourism motivation may be an important policy tool for tourism planners and managers in the development of products and marketing strategies. The empirical analysis is undertaken based on questionnaires administered in 2012 to residents of Guimarães. The present study shows that gender, age and education make a difference with regard to travel motivations.
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The main objective of this paper is to analyse the effect of firms’ performance indicators in explaining the price of stocks in the Portuguese capital market, using a fundamental analysis. In the empirical setting, firms’ performance indicators are gathered into two groups: (1) economic and financial indicators and (2) stock market indicators. Using a sample of 38 firms quoted at Euronext Lisbon, estimates are obtained trough an Ordinary Least Squares (OLS) model and report to December, 31 2007. Results suggest that performance indicators are able to explain the firms’ stock market price. There is a significant positive impact of sales growth and of payout ratio, while we find a statistically significant negative effect of the firm’s financial autonomy on the stock market price for the majority of firms quoted at Euronext Lisbon.
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Management systems standards (MSSs) have developed in an unprecedented manner in the last few years. These MSS cover a wide array of different disciplines, aims and activities of organisations. Also, organisations are populated with an enormous diversity of independent management systems (MSs). An integrated management system (IMS) tends to integrate some or all components of the business. Maximising their integration in one coherent and efficient MS is increasingly a strategic priority and constitutes an opportunity for businesses to be more competitive and consequently, promote its sustainable success. Those organisations that are quicker and more efficient in their integration and continuous improvement will have a competitive advantage in obtaining sustainable value in our global and competitive business world. Several scholars have proposed various theoretical approaches regarding the integration of management sub-systems, leading to the conclusion that there is no common practice for all organisations as they encompass different characteristics. One other author shows that several tangible and intangible gains for organisations, as well as to their internal and external stakeholders, are achieved with the integration of the individual standardised MSs. The purpose of this work was to conceive a model, Flexible, Integrator and Lean for IMSs, according to ISO 9001 for quality; ISO 14001 for environment and OHSAS 18001 for occupational health and safety (IMS–QES), that can be adapted and progressively assimilate other MSs, such as, SA 8000/ISO 26000 for social accountability, ISO 31000 for risk management and ISO/IEC 27001 for information security management, among others. The IMS–QES model was designed in the real environment of an industrial Portuguese small and medium enterprise, that over the years has been adopting, gradually, in whole or in part, individual MSSs. The developed model is based on a preliminary investigation conducted through a questionnaire. The strategy and research methods have taken into consideration the case study. Among the main findings of the survey we highlight: the creation of added value for the business through the elimination of several organisational wastes; the integrated management of the sustainability components; the elimination of conflicts between independent MS; dialogue with the main stakeholders and commitment to their ongoing satisfaction and increased contribution to the company’s competitiveness; and greater valorisation and motivation of employees as a result of the expansion of their skill base, actions and responsibilities, with their consequent empowerment. A set of key performance indicators (KPIs) constitute the support, in a perspective of business excellence, to the follow up of the organisation’s progress towards the vision and achievement of the defined objectives in the context of each component of the IMS model. The conceived model had many phases and the one presented in this work is the last required for the integration of quality, environment, safety and others individual standardised MSs. Globally, the investigation results, by themselves, justified and prioritised the conception of an IMS–QES model, to be implemented at the company where the investigation was conducted, but also a generic model of an IMS, which may be more flexible, integrator and lean as possible, potentiating the efficiency, added value both in the present and, fundamentally, for future.
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Innovative Developments in Virtual and Physical Prototyping
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Pectus excavatum is the most common congenital deformity of the anterior thoracic wall. The surgical correction of such deformity, using Nuss procedure, consists in the placement of a personalized convex prosthesis into sub-sternal position to correct the deformity. The aim of this work is the CT-scan substitution by ultrasound imaging for the pre-operative diagnosis and pre-modeling of the prosthesis, in order to avoid patient radiation exposure. To accomplish this, ultrasound images are acquired along an axial plane, followed by a rigid registration method to obtain the spatial transformation between subsequent images. These images are overlapped to reconstruct an axial plane equivalent to a CT-slice. A phantom was used to conduct preliminary experiments and the achieved results were compared with the corresponding CT-data, showing that the proposed methodology can be capable to create a valid approximation of the anterior thoracic wall, which can be used to model/bend the prosthesis
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Purpose: Precise needle puncture of the renal collecting system is an essential but challenging step for successful percutaneous nephrolithotomy. We evaluated the efficiency of a new real-time electromagnetic tracking system for in vivo kidney puncture. Materials and Methods: Six anesthetized female pigs underwent ureterorenoscopy to place a catheter with an electromagnetic tracking sensor into the desired puncture site and ascertain puncture success. A tracked needle with a similar electromagnetic tracking sensor was subsequently navigated into the sensor in the catheter. Four punctures were performed by each of 2 surgeons in each pig, including 1 each in the kidney, middle ureter, and right and left sides. Outcome measurements were the number of attempts and the time needed to evaluate the virtual trajectory and perform percutaneous puncture. Results: A total of 24 punctures were easily performed without complication. Surgeons required more time to evaluate the trajectory during ureteral than kidney puncture (median 15 seconds, range 14 to 18 vs 13, range 11 to 16, p ¼ 0.1). Median renal and ureteral puncture time was 19 (range 14 to 45) and 51 seconds (range 45 to 67), respectively (p ¼ 0.003). Two attempts were needed to achieve a successful ureteral puncture. The technique requires the presence of a renal stone for testing. Conclusions: The proposed electromagnetic tracking solution for renal collecting system puncture proved to be highly accurate, simple and quick. This method might represent a paradigm shift in percutaneous kidney access techniques
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Rapid prototyping (RP) is an approach for automatically building a physical object through solid freeform fabrication. Nowadays, RP has become a vital aspect of most product development processes, due to the significant competitive advantages it offers compared to traditional manual model making. Even in academic environments, it is important to be able to quickly create accurate physical representations of concept solutions. Some of these can be used for simple visual validation, while others can be employed for ergonomic assessment by potential users or even for physical testing. However, the cost of traditional RP methods prevents their use in most academic environments on a regular basis, and even for very preliminary prototypes in many small companies. That results in delaying the first physical prototypes to later stages, or creating very rough mock-ups which are not as useful as they could be. In this paper we propose an approach for rapid and inexpensive model-making, which was developed in an academic context, and which can be employed for a variety of objects.
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Purpose – The purpose of this paper is to propose a generic model of Integrated Management System of Quality, Environment and Safety (IMS-QES) that can be adapted and progressively to assimilate various Management Systems, of which highlights: ISO 9001 for Quality; ISO 14001 for Environment; OHSAS 18001 for Occupational Health and Safety. Design/methodology/approach – The model was designed in the real environment of a Portuguese Organization and 160 employees were surveyed. The rate response was equal to 86 percent. The conceived model was implemented in a first phase for the integration of Quality, Environment and Safety Management Systems. Findings – Among the main findings of the survey the paper highlights: the elimination of conflicts between individual systems with resources optimization; creation of added value to the business by eliminating several types of wastes; the integrated management of sustainability components in a global market; the improvement of partnerships with suppliers of goods and services; reducing the number of internal and external audits. Originality/value – This case study is one of the first Portuguese empirical researches about IMS-QES and the paper believes that it can be useful in the creation of a Portuguese guideline for integration, namely the Quality Management Systems; Environmental Management Systems and Occupational Health and Safety Management Systems among others.