973 resultados para RISING ELUTION FRACTIONATION


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This work addresses the present-day (<100 ka) mantle heterogeneity in the Azores region through the study of two active volcanic systems from Terceira Island. Our study shows that mantle heterogeneities are detectable even when "coeval" volcanic systems (Santa Barbara and Fissural) erupted less than 10 km away. These volcanic systems, respectively, reflect the influence of the Terceira and D. Joao de Castro Bank end-members defined by Beier et at (2008) for the Terceira Rift Santa Barbara magmas are interpreted to be the result of mixing between a HIMU-type component, carried to the upper mantle by the Azores plume, and the regional depleted MORB magmas/source. Fissural lavas are characterized by higher Ba/Nb and Nb/U ratios and less radiogenic Pb-206/Pb-204, Nd-143/Nd-144 and Hf-176/Hf-177, requiring the small contribution of delaminated sub-continental lithospheric mantle residing in the upper mantle. Published noble gas data on lavas from both volcanic systems also indicate the presence of a relatively undegassed component, which is interpreted as inherited from a lower mantle reservoir sampled by the ascending Azores plume. As inferred from trace and major elements, melting began in the garnet stability field, while magma extraction occurred within the spinel zone. The intra-volcanic system's chemical heterogeneity is mainly explained by variable proportions of the above-mentioned local end-members and by crystal fractionation processes. (C) 2011 Elsevier By. All rights reserved.

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This work addresses the treatment by nanofiltration (NF) of solutions containing NaCN and NH(4)Cl at various pH values. The NF experiments are carried out in a Lab-Unit equipped with NF-270 membranes for model solutions that are surrogates of industrial ammoniacal wastewaters generated in the coke-making processes. The applied pressure is 30 bar. The main objective is the separation of the compounds NaCN and NH(4)Cl and the optimization of this separation as a function of the pH. Membrane performance is highly dependent on solution composition and characteristics, namely on the pH. In fact, the rejection coefficients for the binary model solution containing sodium cyanide are always higher than the rejections coefficients for the ammonium chloride model solution. For ternary solutions (cyanide/ammonium/water) it was observed that for pH values lower than 9 the rejection coefficients to ammonium are well above the ones observed for the cyanides, but for pH values higher than 9.5 there is a drastic decrease in the ammonium rejection coefficients with the increase of the pH. These results take into account the changes that occur in solution, namely, the solute species that are predominant, with the increase of the pH. The fluxes of the model solutions decreased with increased pH. (C) 2010 Elsevier B.V. All rights reserved.

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Dissertação apresentada à Escola Superior de Educação de Lisboa para a obtenção do grau de mestre em Ciências da Educação - Especialidade em Educação Social e Intervenção Comunitária

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Since last decade, the debate on the parameter which reflects prostate cancer sensitivity to fractionation in a radiotherapy treatment, the α/β, has become extensive. Unlike most tumors, the low labeling indices (LI) and large potential doubling time that characterize the prostate tumor led some authors to consider that it may behave as a late responding tissue. So far, the existing studies with regard to this subject point to a low value of α/β, around 2.7 Gy, which may be considered as a therapeutic gain in relation to surrounding normal tissues by using fewer and larger fractions. The aim of this paper is to review several estimates that have been made in the last few years regarding the prostate cancer α/β both from clinical and experimental data, as well as the set of factors that have potentially influenced these evaluations.

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Background: A common task in analyzing microarray data is to determine which genes are differentially expressed across two (or more) kind of tissue samples or samples submitted under experimental conditions. Several statistical methods have been proposed to accomplish this goal, generally based on measures of distance between classes. It is well known that biological samples are heterogeneous because of factors such as molecular subtypes or genetic background that are often unknown to the experimenter. For instance, in experiments which involve molecular classification of tumors it is important to identify significant subtypes of cancer. Bimodal or multimodal distributions often reflect the presence of subsamples mixtures. Consequently, there can be genes differentially expressed on sample subgroups which are missed if usual statistical approaches are used. In this paper we propose a new graphical tool which not only identifies genes with up and down regulations, but also genes with differential expression in different subclasses, that are usually missed if current statistical methods are used. This tool is based on two measures of distance between samples, namely the overlapping coefficient (OVL) between two densities and the area under the receiver operating characteristic (ROC) curve. The methodology proposed here was implemented in the open-source R software. Results: This method was applied to a publicly available dataset, as well as to a simulated dataset. We compared our results with the ones obtained using some of the standard methods for detecting differentially expressed genes, namely Welch t-statistic, fold change (FC), rank products (RP), average difference (AD), weighted average difference (WAD), moderated t-statistic (modT), intensity-based moderated t-statistic (ibmT), significance analysis of microarrays (samT) and area under the ROC curve (AUC). On both datasets all differentially expressed genes with bimodal or multimodal distributions were not selected by all standard selection procedures. We also compared our results with (i) area between ROC curve and rising area (ABCR) and (ii) the test for not proper ROC curves (TNRC). We found our methodology more comprehensive, because it detects both bimodal and multimodal distributions and different variances can be considered on both samples. Another advantage of our method is that we can analyze graphically the behavior of different kinds of differentially expressed genes. Conclusion: Our results indicate that the arrow plot represents a new flexible and useful tool for the analysis of gene expression profiles from microarrays.

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3rd Portuguese Meeting on Medicinal Chemistry and 1st Portuguese-Spanish-Brazilian Meeting on Medicinal Chemistry, Aveiro, 28-30 Novembro 2012.

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Tese de Doutoramento, Geografia (Ordenamento do Território), 25 de Novembro de 2013, Universidade dos Açores.

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In the last years, a rising trend of pollen allergies in urban areas has been attributed to atmospheric pollution. In this work, we investigated the effects of SO2 and NO2 on the protein content, allergenicity, and germination rate of Acer negundo pollen. A novel environmental chamber was assembled to exposure pollen samples with SO2 or NO2 at two different levels: just below and two times the atmospheric hour-limit value acceptable for human health protection in Europe. Results showed that protein content was lower in SO2- exposed pollen samples and slightly higher in NO2-exposed pollen compared to the control sample. No different polypeptide profiles were revealed by SDSPAGE between exposed and nonexposed pollen, but the immunodetection assays indicated higher IgE recognition by all sera of sensitized patients to Acer negundo pollen extracts in all exposed samples in comparison to the nonexposed samples. A decrease in the germination rate of exposed in contrast to nonexposed pollen was verified, which was more pronounced for NO2-exposed samples. Our results indicated that in urban areas, concentrations of SO2 and NO2 below the limits established for human protection can indirectly aggravate pollen allergy on predisposed individuals and affect plant reproduction.

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Copyright © 2014 Entomological Society of America.

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XVIII Simposio Ibérico de Estudios de Biología Marina (SIEBM), Gijón (Asturias), 2 al 5 de septiembre de 2014.

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A crescente preocupação com aspectos ambientais tornou-se uma questão incontornável para as empresas. Assim, a legislação aplicável obriga a maior controlo de qualquer tipo de perigo que ponha em causa a saúde humana ou o ambiente. Deste modo, a Swedwood Portugal é obrigada a implementar algumas medidas de controlo dos produtos químicos. Assim, os objectivos deste estágio curricular fundamentamse em identificar, avaliar e substituir ou minimizar os impactos dos produtos químicos (PQ’s) que, de acordo com especificações REACH (Regulamento da Comissão Europeia, relativo a Registo, Avaliação, Autorização e restrição de substâncias Químicas) e da Swedwood Internacional não podem ser utilizados. Como tal, o trabalho descrito nesta dissertação foi dividido em várias etapas. A primeira etapa consistiu em identificar todos os PQ’s utilizados no sector Board On Frame (BOF) da Swedwood Portugal. Feito este inventário, foi então criada uma base de dados em formato Microsoft Office Access que permitiu compilar a informação mais relevante dos PQ’s, para uma consulta mais simples e expedita, substituindo a já existente e desactualizada base de dados de PQ’s em formato Microsoft Office Excel. No total foram inventariados 243 PQ’s. Contudo, não foi possível obter as Fichas de Segurança de todos e, por isso, apenas 185 foram registados na base de dados. Estes 185 PQ’s existentes no sector BOF da Swedwood Portugal, foram submetidos a uma avaliação das substâncias que os compõem de acordo com uma ferramenta informática criada pela Swedwood Internacional – Substitution Evaluation Key (SEK). Esta ferramenta usa três listas europeias de substâncias químicas que permitem a avaliação de produtos químicos indirectos: Substances of Very High Concern (SVHC) da Agência Europeia de Produtos Químicos (ECHA), Substitute It Now (SIN) da ChemSec (Organização sueca dedicada ao ambiente) e PRIO da Agência Sueca de Produtos Químicos (Kemi). As três listas incluem substâncias de carácter de tal forma perigoso que a sua utilização deve ser restringida ou até eliminada. Logo, os PQ’s indirectos que contenham substâncias presentes em, pelo menos, uma destas listas devem ser imediatamente substituídos por outros cuja avaliação seja positiva. Por outro lado, para produtos químicos directos, as restrições encontram-se numa especificação imposta pela IKEA, IOS-MAT-0066. Concluída a avaliação, foi então necessário encontrar alternativas viáveis aos PQ’s avaliados negativamente. Como tal, a primeira abordagem consistiu em contactar os fabricantes dos PQ’s a substituir de modo a que estes pudessem apresentar as suas próprias alternativas. Caso estes não apresentassem alternativas viáveis, então contactarse- iam novos fornecedores. Dos 185 PQ’s registados na base de dados e avaliados, 30 produtos químicos indirectos existentes nas fábricas não obedeciam aos critérios impostos pela SEK, estando os produtos químicos directos todos de acordo com as imposições da IOS-MAT-0066. Os 30 PQ’s indirectos do Sector BOF da Swedwood Portugal que incluem as substâncias químicas com carácter perigoso apresentam características Cancerígenas, Mutagénicas e tóxicas para a Reprodução (CMR), irritantes e/ou sensibilizantes e perigosas, a longo prazo, para o ambiente. Para estes PQ’s foram apresentadas alternativas viáveis no que concerne a impactos para a saúde ou para o ambiente e os respectivos custos associados (admitindo quantidades mínimas vendidas). Contudo, não foi possível em tempo útil testar estas alternativas no funcionamento da empresa de modo a avaliar a sua eficiência técnica.

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Dissertação para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização de Vias de Comunicação e Transportes

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Dissertação de Mestrado, Ciências Económicas e Empresariais, 11 de Janeiro de 2016, Universidade dos Açores.

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Dissertação de Natureza Científica para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização de Edificações