Gold nanoparticles for the detection of DNA adducts as biomarkers of exposure to acrylamide

The main objective of this thesis was the development of a gold nanoparticle-based methodology for detection of DNA adducts as biomarkers, to try and overcome existing drawbacks in currently employed techniques. For this objective to be achieved, the experimental work was divided in three components: sample preparation, method of detection and development of a model for exposure to acrylamide. Different techniques were employed and combined for de-complexation and purification of DNA samples (including ultrasonic energy, nuclease digestion and chromatography), resulting in a complete protocol for sample treatment, prior to detection. The detection of alkylated nucleotides using gold nanoparticles was performed by two distinct methodologies: mass spectrometry and colorimetric detection. In mass spectrometry, gold nanoparticles were employed for laser desorption/ionisation instead of the organic matrix. Identification of nucleotides was possible by fingerprint, however no specific mass signals were denoted when using gold nanoparticles to analyse biological samples. An alternate method using the colorimetric properties of gold nanoparticles was employed for detection. This method inspired in the non-cross-linking assay allowed the identification of glycidamide-guanine adducts and DNA adducts generated in vitro. For the development of a model of exposure, two different aquatic organisms were studies: a goldfish and a mussel. Organisms were exposed to waterborne acrylamide, after which mortality was recorded and effect concentrations were estimated. In goldfish, both genotoxicity and metabolic alterations were assessed and revealed dose-effect relationships of acrylamide. Histopathological alterations were verified primarily in pancreatic cells, but also in hepatocytes. Mussels showed higher effect concentrations than goldfish. Biomarkers of oxidative stress, biotransformation and neurotoxicity were analysed after prolonged exposure, showing mild oxidative stress in mussel cells, and induction of enzymes involved in detoxification of oxygen radicals. A qualitative histopathological screening revealed gonadotoxicity in female mussels, which may present some risk to population equilibrium.Fundação para a Ciência e Tecnologia/MEC - (SFRH/BD/ 64026/2009). Also, to Xunta de Galicia, for additional funding

New insights on taxonomy, phylogeny and population genetics of Leishmania (Viannia) parasites based on multilocus sequence analysis.

The Leishmania genus comprises up to 35 species, some with status still under discussion. The multilocus sequence typing (MLST)--extensively used for bacteria--has been proposed for pathogenic trypanosomatids. For Leishmania, however, a detailed analysis and revision on the taxonomy is still required. We have partially sequenced four housekeeping genes--glucose-6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), mannose phosphate isomerase (MPI) and isocitrate dehydrogenase (ICD)--from 96 Leishmania (Viannia) strains and assessed their discriminatory typing capacity. The fragments had different degrees of diversity, and are thus suitable to be used in combination for intra- and inter-specific inferences. Species-specific single nucleotide polymorphisms were detected, but not for all species; ambiguous sites indicating heterozygosis were observed, as well as the putative homozygous donor. A large number of haplotypes were detected for each marker; for 6PGD a possible ancestral allele for L. (Viannia) was found. Maximum parsimony-based haplotype networks were built. Strains of different species, as identified by multilocus enzyme electrophoresis (MLEE), formed separated clusters in each network, with exceptions. NeighborNet of concatenated sequences confirmed species-specific clusters, suggesting recombination occurring in L. braziliensis and L. guyanensis. Phylogenetic analysis indicates L. lainsoni and L. naiffi as the most divergent species and does not support L. shawi as a distinct species, placing it in the L. guyanensis cluster. BURST analysis resulted in six clonal complexes (CC), corresponding to distinct species. The L. braziliensis strains evaluated correspond to one widely geographically distributed CC and another restricted to one endemic area. This study demonstrates the value of systematic multilocus sequence analysis (MLSA) for determining intra- and inter-species relationships and presents an approach to validate the species status of some entities. Furthermore, it contributes to the phylogeny of L. (Viannia) and might be helpful for epidemiological and population genetics analysis based on haplotype/diplotype determinations and inferences.publishersversionpublishe

As determinantes da implantação do inventário permanente em Portugal: um estudo empírico

O Decreto-lei n.º 79/2003, de 23 de Abril, aperfeiçoa o Decreto-lei n.º 44/99, de 12 de Fevereiro, ambos foram emitidos pelo Ministério das Finanças de Portugal, e determinam, por razões de gestão, a obrigatoriedade da adopção do inventário permanente a um vasto conjunto de empresas portuguesas, dos sectores comercial, serviços ou industrial. Pressupõem, ex-ante, que a aplicação do supracitado inventário permite a determinação directa do custo das vendas, o aperfeiçoamento do sistema de controlo interno e a melhoria da qualidade da informação financeira, facilitando, igualmente, o processo conducente à auditoria das contas e, contribui, também, para minimizar a evasão fiscal, tornando mais fidedigno o sistema contributivo e, consequentemente, mais credível o processo de determinação do lucro real. Criou, inclusivamente, no Estatuto dos Benefícios Fiscais (art.º 51º), uma medida pedagógica incentivadora da adopção voluntária do inventário permanente, consubstanciada numa majoração de 1,3 do valor da dotação para depreciação de existências, calculado nos termos do Código do Imposto sobre o Rendimento das Pessoas Colectivas (IRC). Com este largo espectro de vantagens e, à partida, sem inconvenientes, interrogamo-nos por que razão a maioria das empresas portuguesas ainda não adoptou semelhante tipo de inventário, apesar de, por lei, ser obrigatório. Neste contexto, é objectivo deste trabalho analisar, não o efeito positivo da adopção do inventário permanente na melhoria das demonstrações financeiras, mas sim, tentar modelizar o comportamento dos gestores e outros agentes incluídos no processo de produção e divulgação da informação financeira, bem como de outros factores determinantes na adopção de semelhante medida de controlo interno. Recorremos, por isso, à concepção de um inquérito que distribuímos por cerca de 200 empresas, sujeitas a Revisão Legal das Contas, de que resultou a elaboração de um modelo de regressão logística capaz de explicar o comportamento dos intervenientes no processo de produção e prestação de contas

Essays on option pricing under alternative one-dimensional diffusions

Essays on Option Pricing under Alternative One-Dimensional Diffusions Given its analytical attractiveness, the process most commonly used in the financial and real options literature is the geometric Brownian motion. However, this assumption embodies some unrealistic implications for the dynamical behavior of the underlying asset price. To overcome this issue, alternative stochastic processes have been considered in the valuation of financial and real options. This thesis examines financial and real options using alternative one-dimensional diffusions, namely the constant elasticity of variance (CEV) and mean-reverting CEV diffusions. This thesis has two main purposes. First, it derives closed-form solutions for computing Greeks of European-style options under both the CEV and CIR (Cox, Ingersoll and Ross) models. Second, it analyzes the optimal entry and exit policy of a firm in the presence of output price uncertainty and costly reversibility of investment under a generalized class of one-dimensional diffusions and shows how the hysteretic band is affected; **** Resumo: Ensaios sobre a Avaliação de Opções sob Difusões Unidimensionais Alternativas Na avaliação de opções financeiras e reais, o processo mais utilizado na literatura ´e o movimento Browniano geométrico. Contudo, esta suposição ao incorpora algumas implicações irrealistas para o comportamento dinâmico do preço do activo subjacente. Para ultrapassar estas limitações, têm sido considerados processos estocásticos alternativos para a avaliação de opções financeiras e reais. Esta tese analisa opções, financeiras e reais, utilizando difusões unidimensionais alternativas, nomeadamente as difusões elasticidade constante da vari ˆancia (CEV - constant elasticity of variance) e CEV com reversão `a média. Esta tese tem dois objectivos principais. Primeiro, derivar soluções analíticas para calcular as letras gregas de opções de tipo Europeu para os modelos CEV e CIR (Cox, Ingersoll e Ross). Segundo, analisar a política óptima de entrada e de saída de uma empresa na presença de incerteza no prec¸o do output e de reversibilidade dos custos de investimento, para uma classe generalizada de difusões unidimensionais, e mostrar a influência sobre a banda de histerese económica

Speed and Accuracy Comparison of Noncentral Chi-Square Distribution Methods for Option Pricing and Hedging under the CEV Model

Pricing options and evaluating greeks under the constant elasticity of variance (CEV) model require the computation of the noncentral chi-square distribution function. In this article, we compare the performance in terms of accuracy and computational time of alternative methods for computing such probability distributions against an xternally tested benchmark. In addition, we present closed-form solutions for computing greek measures under the CEV option pricing model for both beta 2, thus being able to accommodate direct leverage effects as well as inverse leverage effects that are frequently observed in the options markets

Resting-state cortical hubs in youth organize into four categories

During childhood, neural systems supporting high-level cognitive processes undergo periods of rapid growth and refinement, which rely on the successful coordination of activation across the brain. Some coordination occurs via cortical hubs-brain regions that coactivate with functional networks other than their own. Adult cortical hubs map into three distinct profiles, but less is known about hub categories during development, when critical improvement in cognition occurs. We identify four distinct hub categories in a large youth sample (n = 567, ages 8.5-17.2), each exhibiting more diverse connectivity profiles than adults. Youth hubs integrating control-sensory processing split into two distinct categories (visual control and auditory/motor control), whereas adult hubs unite under one. This split suggests a need for segregating sensory stimuli while functional networks are experiencing rapid development. Functional coactivation strength for youth control-processing hubs are associated with task performance, suggesting a specialized role in routing sensory information to and from the brain\u27s control system

Entry and Exit Decisions under Uncertainty for a Generalized Class of One-Dimensional Diffusions

Abstract We consider the optimal entry and exit policy of a firm in the presence of output price uncertainty and costly reversibility of investment under a generalized class of one-dimensional diffusions accommodating different drift and volatility specifications. This will allow us to analyze how output price uncertainty and costly reversibility affects the optimal entry and exit policy of a competitive price-taking firm, and how the hysteretic band is affected by the choice of the appropriate stochastic process

Pricing and hedging bond options and sinking-fund bonds under the CIR model

This article derives simple closed-form solutions for computing Greeks of zero-coupon and coupon-bearing bond options under the CIR interest rate model, which are shown to be accurate, easy to implement, and computationally highly e cient. These novel analytical solutions allow us to extend the literature in two other directions. First, the static hedging portfolio approach is used for pricing and hedging American-style plain-vanilla zero-coupon bond options under the CIR model. Second, we derive analytically the comparative static properties of sinking-fund bonds under the same interest rate modeling setup.Manuela Larguinho and Carlos A. Braumann belong to the research center CIMA (Centro de Investigação em Matemática e Aplicações, Instituto de Investigação e Formação Avançada, Universidade de Évora), supported by FCT (Fundação para a Ciência e a Tecnologia, Portugal), project UID/04674/2020. José Carlos Dias belongs to the Business Research Unit (BRU-IUL) and acknowledges the support provided by FCT [grant number UIDB/00315/2020]

As determinantes da implantação do inventário permanente em Portugal: um estudo empírico

O Decreto-lei n.º 79/2003, de 23 de Abril, aperfeiçoa o Decreto-lei n.º 44/99, de 12 de Fevereiro, ambos foram emitidos pelo Ministério das Finanças de Portugal, e determinam, por razões de gestão, a obrigatoriedade da adopção do inventário permanente a um vasto conjunto de empresas portuguesas, dos sectores comercial, serviços ou industrial. Pressupõem, ex-ante, que a aplicação do supracitado inventário permite a determinação directa do custo das vendas, o aperfeiçoamento do sistema de controlo interno e a melhoria da qualidade da informação financeira, facilitando, igualmente, o processo conducente à auditoria das contas e, contribui, também, para minimizar a evasão fiscal, tornando mais fidedigno o sistema contributivo e, consequentemente, mais credível o processo de determinação do lucro real. Criou, inclusivamente, no Estatuto dos Benefícios Fiscais (art.º 51º), uma medida pedagógica incentivadora da adopção voluntária do inventário permanente, consubstanciada numa majoração de 1,3 do valor da dotação para depreciação de existências, calculado nos termos do Código do Imposto sobre o Rendimento das Pessoas Colectivas (IRC). Com este largo espectro de vantagens e, à partida, sem inconvenientes, interrogamo-nos por que razão a maioria das empresas portuguesas ainda não adoptou semelhante tipo de inventário, apesar de, por lei, ser obrigatório. Neste contexto, é objectivo deste trabalho analisar, não o efeito positivo da adopção do inventário permanente na melhoria das demonstrações financeiras, mas sim, tentar modelizar o comportamento dos gestores e outros agentes incluídos no processo de produção e divulgação da informação financeira, bem como de outros factores determinantes na adopção de semelhante medida de controlo interno. Recorremos, por isso, à concepção de um inquérito que distribuímos por cerca de 200 empresas, sujeitas a Revisão Legal das Contas, de que resultou a elaboração de um modelo de regressão logística capaz de explicar o comportamento dos intervenientes no processo de produção e prestação de contas.The Decree-law n.º 79/2003, of 23 of April, perfects the Decree-law n.º 44/99, of 12 of February, both had been emitted by the Ministry of the Finances of Portugal, and determine, for management reasons, the obligation of the adoption of the permanent inventory to a vast set of Portuguese companies, of the sectors commercial, services or industrial. They estimate, former-before, that the application of the above-mentioned inventory allows to the determination direct of the cost of sales, the perfectioning of the system of internal control and the improvement of the quality of the financial information, facilitating, equally, the conducive process to the auditorship of the accounts and, contributes, also, to minimize the fiscal evasion, becoming trustworther contribution system and, in consequence, the process of determination of the profit Real. It created, inclusively, in the Statute of the Tax benefits (art.º 51º), an pedagogical measure of the voluntary adoption of the permanent inventory, in an increase of 1,3 of the value of the endowment for depreciation of existences, calculated in the terms of the Code of the Tax on the Income (IRC). With this wide specter of advantages and, to the departure, without inconveniences, we interrogate ourselves why reason the majority of the Portuguese companies still did not adoption similar type of inventory, although, for law, obligator being. In this context, he is aim of this work to analyze, not it positive effect of the adoption of the permanent inventory in the improvement of the financial demonstrations, but yes, to try to modeless the enclosed behaviour of the managers and other agents in the production process and spreading of the financial information, as well as of other determinative factors in the adoption of measured fellow creature of internal control. We appeal, therefore, to the conception of an inquiry that we distribute for about 200 companies, citizens the Legal Revision of Accounts, of that the elaboration of a model of logistic regression capable resulted to explain the behaviour of intervening in the process of production and the rendering of accounts

Ultrasonic energy for proteomics: when, where and how

Comunicaciones a congreso