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Avaliação da exposição ocupacional, em laboratórios, de múltiplos agentes químicos, por longo período e em baixas concentrações; Assessment of occupational exposure to multiple chemicals for a long period and in low concentrations in laboratories.

Rebelo, Paulo Antonio de Paiva
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 25/05/2007 Português
Relevância na Pesquisa
36.91%
Objetivo Avaliar o perfil da exposição ocupacional a agentes químicos, em laboratórios, e verificar os impactos na avaliação de risco decorrentes das mudanças nos limites de exposição ocupacional (LEO) e na legislação federal brasileira. Metodologia Revisão de literatura relativa à exposição ocupacional a substâncias químicas, referentes a: conceituação de risco; desenho das curvas dose-resposta; identificação dos fatores que interferem na relação dose-efeito; conceitos de exposição por longo período, da exposição múltipla e em baixas concentrações; e fatores de confusão na monitoração ocupacional. Realização de estudo transversal no Centro de Pesquisas da Petrobras, para avaliar o perfil de exposição a agentes químicos de 3.000 trabalhadores, com atividades preponderantes em laboratórios, metade das quais com exposição em baixas concentrações e por longo período, tendo por base as avaliações ambientais do ano de 2004. Análise temporal dos valores de LEO da American Conferrence of Governmental Industrial Hygienists (ACGIH) e levantamento das mudanças nas legislações federal previdenciária, trabalhista e de saúde nos aspectos relacionados à exposição a agentes químicos. Resultados Foram identificadas 484 substâncias químicas em 243 postos de trabalho...

Avaliação da concentração de elementos químicos tóxicos na merenda escolar de crianças da cidade de Ribeirão Preto e estimativa de suas ingestões diárias; Assessment of toxic chemicals concentration in the school

Nacano, Letícia Ramos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 19/09/2012 Português
Relevância na Pesquisa
36.52%
A contaminação do ambiente por elementos químicos é um problema crescente em várias regiões do planeta. Muitos destes elementos químicos, que incluem o Cd, Pb e As são tóxicos aos humanos.De acordo com os órgãos de saúde como a Organização Mundial da Saúde (OMS), 90% da ingestão destes elementos tóxicos ocorre por meio do consumo de alimentos (Tavares et al., 1992; Virga et al., 2007). Neste sentido, a estimativa da exposição pela alimentação é fundamental para avaliação de risco de possíveis efeitos adversos. A avaliação da exposição alimentar consiste em associar os dados de consumo alimentar de uma determinada população com as concentrações observadas dos elementos químicos em sua dieta (Nasreddine, 2010). Neste sentido, o objetivo deste trabalho foi, determinar a ingestão diária dos elementos químicos tóxicos (As, Pb e Cd) em crianças em idade escolar através dos alimentos fornecidos pela Prefeitura de Ribeirão Preto nas merendas escolares. A metodologia utilizada no trabalho foi de dupla dieta, onde os alimentos analisados já estão prontos para o consumo. As merendas fornecidas por duas escolas municipais (infantil e ensino fundamental) e a cozinha piloto foram coletadas durante todos os dias letivos dos meses de março...

Responsabilidade civil pelos danos ambientais ocasionados por acidentes durante o transporte rodoviário de produtos químicos perigosos; Civil responsibility for environmental damage caused by accidents during the transport of hazardous chemicals

Agnes, Patrícia Stein
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Trabalho de Conclusão de Curso Formato: application/pdf
Português
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36.52%
O transporte de produtos químicos perigosos envolve grande risco de danos ambientais, por estar exposto a inúmeros fatores internos e externos. A responsabilidade civil ambiental é a forma de reparar os prejuízos patrimoniais e extrapatrimoniais ocasionados pelos acidentes ocorridos neste ramo de atividade. Para tanto, fez-se necessário verificar a existência de limites para aplicação deste instituto, bem como a determinação de quem são os responsáveis pelas reparações eventualmente necessárias. Entendemos que a responsabilização solidária deve envolver todos os que lucram com a atividade. Nesse sentido, correta a aplicação da responsabilidade civil objetiva de todos os envolvidos na relação comercial. Também será solidariamente responsabilizado o Estado, mas não de forma integral, pelos danos ambientais provocados por terceiros, por ter o dever fiscalizar e impedir que tais danos aconteçam. Quanto aos compradores, vendedores e transportadores de produtos químicos perigosos, não existe o mesmo entendimento pacífico quanto à aplicação ou não da Teoria do Risco Integral em casos de acidentes, embora haja uma tendência maior de aplicação deste instituto, tanto na jurisprudência quanto na doutrina consultada.; The dangerous chemical transportation involves a great risk of environmental damage...

Prenatal testosterone exposure as a model for the study of endocrine-disrupting chemicals on the gerbil prostate

Biancardi, Manoel F.; Perez, Ana P. S.; Goes, Rejane M.; Santos, Fernanda C. A.; Vilamaior, Patricia S. L.; Taboga, Sebastiao R.
Fonte: Royal Soc Medicine Press Ltd Publicador: Royal Soc Medicine Press Ltd
Tipo: Artigo de Revista Científica Formato: 1298-1309
Português
Relevância na Pesquisa
36.52%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Processo FAPESP: 07/06862-3; The development of the prostate depends on a precise androgenic control, so sensible interferences may predispose this gland to develop prostatic diseases during life. These aspects are of interest and preoccupation, since human beings are exposed to a growing number of endocrine-disrupting chemicals with androgenic potential. Therefore, our aim was to evaluate the prostates of adult gerbils exposed to testosterone during intrauterine life. Serological, morphological, morphometric-stereologic, immunohistochemical and three-dimensional reconstruction analyses were used. We found that the testosterone effects were dose-dependent and more harmful to females, leading to the development of masculine characteristics, evidenced by an increased anogenital distance, and absence of vaginal opening and the ectopic development of prostatic tissue. Moreover, premalignant lesions, such as prostatic intraepithelial neoplasia, were observed in addition to inflammatory foci in the prostate. The results showed that the prenatal exposure to testosterone may affect the reproductive system...

Utilização de geotecnologias para a avaliação do potencial de degradação hidrica das aguas superficiais por agroquimicos : caso da sub-bacia do Rio das Antas, Bueno Brandão, MG; The use of geo-technologies to evaluate the potentiality of hydro-degradation in superficial waters by agro-chemicals : case of Antas River watershed, Bueno Brandão, MG

Vassiliki Terezinha Galvão Boulomytis
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 29/08/2008 Português
Relevância na Pesquisa
36.77%
Na região de Bueno Brandão, Sul de MG, a sub-bacia do Rio das Antas está localizada à montante da captação de águas para o abastecimento público municipal e é passiva de degradação qualitativa devido, principalmente, às atividades agropecuárias impactantes. A bataticultura se destaca entre elas devido às seguintes características: uso intensivo de agroquímicos, plantio em terrenos com declividades superiores a 20% e proximidade ou intervenção em Áreas de Preservação Permanente (APP). Deste modo, esta foi a área de estudo escolhida, a fim de fornecer um prédiagnóstico ambiental através do uso de geotecnologias. Alguns locais de plantio de batatas foram pontualmente cadastrados, utilizando-se de um GPS de navegação, onde foram obtidos dados referentes aos agroquímicos utilizados nas lavouras. Estes pontos cadastrais foram utilizados como amostras no processo de classificação supervisionada da imagem de satélite LANDSAT TM5, adquirida no período de préplantio de julho/agosto de 2007. O software utilizado como Sistema de Informações Geográficas (SIG) foi o SPRING, versão 4.3.3 (2007). A classificação de risco da subbacia foi obtida após a realização de operações lógicas e algébricas com os mapas temáticos de APP...

Sea bass (Dicentrarchus labrax) : a model organism for the screening of estrogenic chemicals in marine surface waters?

Correia, Ana D.; Freitas, S.; Lamoree, M. H.; Boiij, P.; Scholze, M.; Maňanós, E.; Henriques, M. A. Reis
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em 18/04/2004 Português
Relevância na Pesquisa
36.85%
Society of Environmental Toxicology and Chemistry - SETAC Europe 14th Annual Meeting, Prague, Czech Republic, April 2004.; There is growing concern that aquatic wildlife in surface waters of the European Union is exposed to natural and man-made chemicals that have the ability to mimic estrogens and lead to reproductive dysfunction. Estrogenic responses in fish are the net result of complex chains of events involving the uptake, distribution and metabolism of test agents until they interact with their target sites. Typically these aspects cannot be modelled in short-term cell-based assays, only studies with vertebrates offer the opportunity to assess potential interactions of test compounds at higher organisational levels. However, studies with endocrine disrupting chemicals have been performed mainly with freshwater organisms. The sensitivity of a marine fish species to different estrogenic chemicals was investigated under chronic exposure conditions. This work is part of a study focusing on the combination effects of mixtures of estrogenic chemicals in marine and freshwater organisms (ACE, EVK1-CT-2001-100). As test organism the sea bass (Dicentrarchus labrax) was selected, a common species in European marine systems. Juveniles were exposed under a flow-through system for 14 days for a set of reference chemicals (17Ã -estradiol...

Sea bass (Dicentrarchus labrax) : a model organism for assessing multi-level responses to estrogenic chemicals in marine surface waters

Correia, Ana D.; Freitas, S.; Lamoree, M. H.; Scholze, M.; Maňanós, E.; Henriques, M. A. Reis
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em 05/09/2004 Português
Relevância na Pesquisa
36.71%
Resumo apresentado sob poster ao 5th International Symposium of Fish Endocrinology, CAstellon, Spain, Setember 5-9, 2004.; There is growing concern that aquatic wildlife in surface waters of the European Union is exposed to natural and man-made chemicals that have the ability to mimic estrogens and lead to reproductive dysfunction. Estrogenic responses in fish are the net result of complex chains of events involving the uptake, distribution and metabolism of test agents until they interact with their target sites. Typically these aspects cannot be modelled in short-term cell-based assays, only studies with vertebrates offer the opportunity to assess potential interactions of test compounds at higher organisational levels. The most widely studied biological response in fish to environmental estrogens is the production of vitellogenin (Vtg). However, few studies have attempted to link this endpoint with effects on xenobiotic biotransformation enzymes and genotoxic responses. This work is part of a study focusing on the combination effects of mixtures of estrogenic chemicals in marine and freshwater organisms. As test organism the sea bass (Dicentrarchus labrax) was selected, a common species in European marine systems. Juveniles were exposed under a flow-through system for 14 days to the natural estrogen 17ß-estradiol and ethynylestradiol. Actual chemical concentrations in the water-column were determined by gas chromatography with ion trap detection. Effects at subcellular level were analysed using Vtg as a reference endpoint [1]. Its relevance is evaluated by further investigations on liver 7-ethoxyresorufin-O-deethylase (EROD) activity and erythrocytic nuclear abnormalities [2]. These measurements were integrated with organism level endpoints (i.e. condition factor...

Pipelines for New Chemicals: a strategy to create new value chains and stimulate innovation-based economic revival in Southern European countries

Timmis, Kenneth; Lorenzo, Victor de; Verstraete, Willy; Garcia, José Luis; Ramos, Juan Luis; Santos, Helena; Economidis, Ioannis; Nogales, Balbina; Timmis, James Kenneth; Fonseca, César; Pruzzo, Carla; Karagouni, Amalia; Panopoulos, Nickolas; Dixon, Ber
Fonte: John Wiley & Sons Publicador: John Wiley & Sons
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
Relevância na Pesquisa
36.71%
Countries of Southern Europe are currently suffering from severe socio-economic pain resulting from high debt levels and austerity measures which constrain investment in innovation-based recovery strategies that are essential for entry into a long-term sustainable period of increasing employment and wealth creation. Young university-educated people are particularly innovative, and hence vital to the development of such strategies, but employment opportunities are poor and many are forced to seek employment that neither profits from their training nor satisfies their justified career expectations, or to emigrate. They are the ‘lost generation’. A strategy is proposed here for the creation of Pipelines for New Chemicals, national centre-network partnerships for the discovery-synthesis of new chemicals obtained though harvesting new biological diversity, and their exploitation to develop new medicines, agrochemicals, materials, and other products and applications. The goal is to create new regional motors of economic growth and development, by harnessing the knowledge, motivation and innovation potential of the excellently educated young people of Europe to catalyse the development of new small, medium and large enterprises centred around novel chemicals...

Exposure to Polyfluoroalkyl Chemicals and Attention Deficit/Hyperactivity Disorder in U.S. Children 12–15 Years of Age

Hoffman, Kate; Webster, Thomas F.; Weinberg, Janice; Vieira, Verónica M.; Weisskopf, Marc G.
Fonte: National Institute of Environmental Health Sciences Publicador: National Institute of Environmental Health Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.52%
Background: Polyfluoroalkyl chemicals (PFCs) have been widely used in consumer products. Exposures in the United States and in world populations are widespread. PFC exposures have been linked to various health impacts, and data in animals suggest that PFCs may be potential developmental neurotoxicants. Objectives: We evaluated the associations between exposures to four PFCs and parental report of diagnosis of attention deficit/hyperactivity disorder (ADHD). Methods: Data were obtained from the National Health and Nutrition Examination Survey (NHANES) 1999–2000 and 2003–2004 for children 12–15 years of age. Parental report of a previous diagnosis by a doctor or health care professional of ADHD in the child was the primary outcome measure. Perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS) levels were measured in serum samples from each child. Results: Parents reported that 48 of 571 children included in the analysis had been diagnosed with ADHD. The adjusted odds ratio (OR) for parentally reported ADHD in association with a 1-μg/L increase in serum PFOS (modeled as a continuous predictor) was 1.03 [95% confidence interval (CI), 1.01–1.05]. Adjusted ORs for 1-μg/L increases in PFOA and PFHxS were also statistically significant (PFOA: OR = 1.12; 95% CI...

A Strategy for Comparing the Contributions of Environmental Chemicals and Other Risk Factors to Neurodevelopment of Children

Bellinger, David C.
Fonte: National Institute of Environmental Health Sciences Publicador: National Institute of Environmental Health Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.71%
Background: The impact of environmental chemicals on children’s neurodevelopment is sometimes dismissed as unimportant because the magnitude of the impairments are considered to be clinically insignificant. Such a judgment reflects a failure to distinguish between individual and population risk. The population impact of a risk factor depends on both its effect size and its distribution (or incidence/prevalence). Objective: The objective was to develop a strategy for taking into account the distribution (or incidence/prevalence) of a risk factor, as well as its effect size, in order to estimate its population impact on neurodevelopment of children. Methods: The total numbers of Full-Scale IQ points lost among U.S. children 0–5 years of age were estimated for chemicals (methylmercury, organophosphate pesticides, lead) and a variety of medical conditions and events (e.g., preterm birth, traumatic brain injury, brain tumors, congenital heart disease). Discussion: Although the data required for the analysis were available for only three environmental chemicals (methylmercury, organophosphate pesticides, lead), the results suggest that their contributions to neurodevelopmental morbidity are substantial, exceeding those of many nonchemical risk factors. Conclusion: A method for comparing the relative contributions of different risk factors provides a rational basis for establishing priorities for reducing neurodevelopmental morbidity in children.

Rethinking the Role of Information in Chemicals Policy: Implications for TSCA and REACH

Koch, Lars; Ashford, Nicholas
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.81%
This article analyses the role of different kinds of information for minimizing or eliminating the risks due to the production, use, and disposal of chemical substances and contrasts it with present and planned (informational) regulation in the United States and the European Union, respectively. Some commentators who are disillusioned with regulatory approaches have argued that informational tools should supplant mandatory regulatory measures unflatteringly described as ‘‘command and control.’’ Critics of this reformist view are concerned with the lack of technology-innovation forcing that results frominformational policies alone.Weargue that informational tools can be made more technology inducing e and thus more oriented towards environmental innovations e than they are under current practices, with or without complementary regulatory mechanisms, although a combination of approachesmay yield the best results. The conventional approach to chemicals policy envisions a sequential process that includes three steps of (1) producing or collecting risk-relevant information, (2) performing a risk assessment or characterization, followed by (3) risk management practices, often driven by regulation. We argue that such a sequential process is too static...

Fatores determinantes das estratégias de gestão ambiental na indústria millennium inorganic chemicals: cristal global

Alves, Wellington
Fonte: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Engenharia de Produção; Estratégia; Qualidade; Gestão Ambiental; Gestão da Produção e Operações Publicador: Universidade Federal do Rio Grande do Norte; BR; UFRN; Programa de Pós-Graduação em Engenharia de Produção; Estratégia; Qualidade; Gestão Ambiental; Gestão da Produção e Operações
Tipo: Dissertação Formato: application/pdf
Português
Relevância na Pesquisa
36.71%
The general aim of this research was to analyze the factors that determine the environmental management strategies in the industry Millennium Inorganic Chemicals: Crystal Global, but also analyze which environmental management strategies are used by industry. For the achievement of the proposed objective, we conducted a case study organization based in twenty-eight environmental management strategies raised in the literature. Following this survey, it was possible to ascertain which of these strategies are used in the industry studied, as well as which factors are decisive for the implementation of these. The research is characterized as qualitative and applied, as the goals is exploratory and descriptive, with regard to the data, these were obtained through interviews with the directors of the organization and also documents made available by the industry. As a main result, it was realized that the industry practices twenty-eight twenty of environmental management strategies proposed in this study, the scale Waste Management that encompasses more strategies. Regarding the determinants realized that the endogenous factors that are most pressing for the organization creating environmental strategies, and these determinants, since the exogenous...

Kinetic and Stoichiometric Modeling of the Metabolism of Escherichia coli for the Synthesis of Biofuels and Chemicals

Cintolesi Makuc, Angela
Fonte: Universidade Rice Publicador: Universidade Rice
Português
Relevância na Pesquisa
36.52%
This thesis presents the mathematical modeling of two new Escherichia coli platforms with economical potential for the production of biofuels and chemicals, namely glycerol fermentation and the reversal of the β-oxidation cycle. With the increase in traditional fuel prices, alternative renewable energy sources are needed, and the efficient production of biofuels becomes imperative. So far studies have focused on using glucose as feedstock for the production of ethanol and other fuels, but a recent increase in glycerol availability and its consequent decrease in price make it an attractive feedstock. Furthermore, the reversed β-oxidation cycle is a highly efficient mechanism for the synthesis of long-chain products. These two platforms have been reported experimentally in E. coli but their mathematical modeling is presented for the first time here. Because mathematical models have proved to be useful in the optimization of microbial metabolism, two complementary models were used in this study: kinetic and stoichiometric. Kinetic models can identify the control structure within a specific pathway, but they require highly detailed information, making them applicable to small sets of reactions. In contrast, stoichiometric models require only mass balance information...

Comparison of shor-term estrogenicity tests for identification of hormone-disrupting chemicals

Andersen, Helle Raun; Andersson, Anna-Maria; Arnold, Steven F.; Autrup, Herman; Barfoed, Marianne; Beresford, Nicola; Bjerregaard, Poul; Christiansen, Lisette; Gissel, Birgitte; Hummel, Ren??; J??rgensen, Eva B.; Korsgaard, Bodil; Guevel, Remy Le; Leffers
Fonte: National Institute of Environmental Health Sciences Publicador: National Institute of Environmental Health Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.63%
The aim of this study was to compare results obtained by eight different short-term assays of estrogenlike actions of chemicals conducted in 10 different laboratories in five countries. Twenty chemicals were selected to represent direct-acting estrogens, compounds with estrogenic metabolites, estrogenic antagonists, and a known cytotoxic agent. Also included in the test panel were 17??-estradiol as a positive control and ethanol as solvent control. The test compounds were coded before distribution. Test methods included direct binding to the estrogen receptor (ER), proliferation of MCF-7 cells, transient reporter gene expression in MCF-7 cells, reporter gene expression in yeast strains stably transfected with the human ER and an estrogen-responsive reporter gene, and vitellogenin production in juvenile rainbow trout. 17??-Estradiol, 17??-ethynyl estradiol, and diethylstilbestrol induced a strong estrogenic response in all test systems. Colchicine caused cytotoxicity only. Bisphenol A induced an estrogenic response in all assays. The results obtained for the remaining test compounds???tamoxifen, ICI 182.780, testosterone, bisphenol A dimethacrylate, 4-n-octylphenol, 4-n-nonylphenol, nonylphenol dodecylethoxylate, butylbenzylphthalate...

Prenatal Exposures to Environmental Chemicals and Children's Neurodevelopment: An Update

Bellinger, David C.
Fonte: Occupational Safety and Health Research Institute Publicador: Occupational Safety and Health Research Institute
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.71%
This review surveys the recent literature on the neurodevelopmental impacts of chemical exposures during pregnancy. The review focuses primarily on chemicals of recent concern, including phthalates, bisphenol-A, polybrominated diphenyl ethers, and perfluorinated compounds, but also addresses chemicals with longer histories of investigation, including air pollutants, lead, methylmercury, manganese, arsenic, and organophosphate pesticides. For some chemicals of more recent concern, the available literature does not yet afford strong conclusions about neurodevelopment toxicity. In such cases, points of disagreement among studies are identified and suggestions provided for approaches to resolution of the inconsistencies, including greater standardization of methods for expressing exposure and assessing outcomes.

Short- and medium-term effects of three fire fighting chemicals on the properties of a burnt soil

Couto Vázquez, Alejandra; González-Prieto, Serafín J.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 639866 bytes; application/pdf
Português
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Final version of the paper available at: http://www.sciencedirect.com/science/journal/00489697; The impact of three fire fighting chemicals (FFC) on 11 chemical soil properties and on soil recovery (0–2 cm depth) was evaluated 1, 30, 90 and 365 days after a prescribed fire. Five treatments were considered: unburnt soil (US) and burnt soil with 2 l m−2 of water alone (BS) or mixed with the foaming agent Auxquímica RFC-88 at 1% (BS + Fo), Firesorb at 1.5% (BS + Fi) and FR Cross ammonium polyphosphate at 20% (BS + Ap). At t = 1 day, soil pH increases in the order US < BS ≤ BS + Fo, BS + Fi < BS + Ap, which was most likely due to the accumulation of ashes, the reduction of organic acids and the cations supplied by FFC. In all burnt treatments, soil pH remained significantly higher than in US up until t = 90 days. SOM richness remained similar and constant until t = 90 days in all plots, but, probably due to fire-triggered erosion, at t = 365 days it was significantly lower in BS + Ap (C, N), BS and BS + Fo (C) than in US. Immediately after the fire, soil δ15N decreased in all burnt soils (significatively in BS + Ap) due to the inputs of 15N depleted ashes from leguminous vegetation. Compared with US, soil δ15N increased significantly in all burnt plots between t = 90 days (30 days in BS + Ap) and t = 365 days...

Research and Development Competition in the Chemicals Industry

Finger, Stephen R
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação Formato: 563262 bytes; application/pdf
Publicado em 24/04/2008 Português
Relevância na Pesquisa
36.52%
This dissertation is composed of two related chapters dealing with research and development. I evaluate the effects of the Research and Experimentation Tax Credit on the Chemicals Industry and then examine the determinants of research joint ventures and technological licenses. The first chapter evaluates the equilibrium effects of the Research and Experimentation Tax Credit, taking into consideration firm interactions. The tax credit was put into place to counteract the underinvestment in private R&D caused by firms not internalizing the benefits of technological spillovers from their research. However, this rationale ignored the impact of product market competition. I propose and estimate a structural dynamic oligopoly model of competition in intellectual assets to capture the impact of interactions between firms in the industry. I estimate the dynamic parameters of the model using methods from Bajari, Benkard, and Levin (2007). I build upon previous estimators by incorporating unobserved firm-level heterogeneity using techniques from Arcidiacono and Miller (2007). I use publicly available panel data on firms' R&D expenditures and their patenting activities to measure innovations. In the data, I observe firms that persistently invest more in research and generate more innovations than other firms that are observationally similar. I model this heterogeneity as an unobserved state that raises a firm's research productivity. In my analysis...

An Experimental and Modeling Study of the Adsorption and Desorption of Heavy Metals and Organic Chemicals with Applications to Sewage Sludge and Dredged Sediments in the Marine Environment

DiToro, Dominic; Mahony, John D.
Fonte: Universidade de Delaware Publicador: Universidade de Delaware
Tipo: Relatório Formato: 4611000 bytes; application/pdf
Português
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The stated purpose of the proposed research was to establish the applicability of the reversible-resistant model of adsorption and desorption of toxic chemicals from dredged material and digested sewage sludge, and to make any necessary changes In the model as dictated by the experimental results. However, while this purpose was ultimately fulfilled, the actual pathway of the investigation was somewhat different from that envisioned in the original proposal and, as will be seen, the role of particle concentration and ultimately kinetics must be included if a clear understanding of the fate of toxic substances in the marine environment is to be attained.

Transportation Accidents Involving Hazardous Chemicals Versus Those Involving Dangerous Nuclear Materials

Quarantelli, E. L.
Fonte: Disaster Research Center Publicador: Disaster Research Center
Tipo: Outros Formato: 4539983 bytes; application/pdf
Português
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36.63%
In this chapter we focus on transportation accidents which involve hazardous chemicals and those which involve dangerous nuclear material. The chapter is organized into four sections. In the first section, we address the general kinds of risks to people and things which are inherent in the transport of dangerous nuclear material, especially spent fuel. In the absence of a meaningful data base of actual and past incidents, we must posit a hypothetical, future worst-case scenario for the analytical purposes required by the projected comparison. In the second section of the chapter we briefly examine the complete range of possible incidents of chemical hazards in transportation accidents. We observe at this point that hazardous chemicals are far more heterogenous in their potential and, in the extreme case, can be far more dangerous than the risks posed by the worst-case nuclear danger scenario we use. The third section of the chapter is devoted to a discussion of the common and unique functions relating to private and public sector preparations for and responses to both kinds of transportation hazards, as they have been reported in the speculative and research literature. Our general finding is that two kinds of dangers discussed require somewhat different rather than similar responses. We conclude the chapter with a summary of policy implications for emergency management derived from the functional comparison of the nuclear and nonnuclear hazards discussed in the preceding section. The major conclusion is that despite dissimilarities in the two threats...

Endocrine disrupting chemicals (phenol and phthalates) in the South African environment: a need for more monitoring

Olujimi,OO; Fatoki,OS; Odendaal,JP; Okonkwo,JO
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2010 Português
Relevância na Pesquisa
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There has been increasing concern about the impacts of exposure to chemical compounds with endocrine disrupting activities in the environment, especially aquatic environments, to wildlife and humans. South Africa is known to have used and abused most chemicals listed by developed and developing countries as endocrine-disrupting chemicals. Endocrinedisrupting chemicals have been reported in water, sediment and serum, as well as in fish tissue samples, at a level that could trigger endocrine disruption in humans and wildlife. Although some monitoring has been reported, particularly in water systems within the country, information on EDCs in other environmental matrices is scanty. The water systems monitored so far are very few. The strongest economy in Africa, and an emerging world economy depending on agriculture, mining, manufacturing and industry, needs to focus more on monitoring and to strengthen government organs and institutions to monitor and ensure environmental safety.