959 resultados para third-order non-linearity


Relevância:

30.00% 30.00%

Publicador:

Resumo:

In order to evaluate the potential allergenicity of Blomia tropicalis (Bt) antigen, IgE production of both specific and non-specific for Bt antigen was monitored in BALB/c mice after exposure to the antigen by nasal route. It was evidenced that B. tropicalis contains a functional allergen in its components. The allergenic components, however, when administered intranasally without any adjuvant, did not function to induce IgE response within a short period. On the other hand, intranasal inoculation of Bt antigens augmented serum IgE responses in mice pretreated by a subcutaneous priming injection of the same antigens. Inoculation of Bt antigen without subcutaneous priming injections induced IgE antibody production only when the antigen was continuously administered for a long period of over 24 weeks. Even when the priming injection was absent, the Bt antigen inoculated with cholera toxin (CT) as a mucosal adjuvant also significantly augmented the Bt antigen-specific IgE responses depending on the dose of CT co-administered. The present study also demonstrated that Bt antigen/CT-inoculated mice showed increased non-specific serum IgE level and peripheral blood eosinophil rates without noticeable elevations of the total leukocyte counts. The immunoblot analysis demonstrated 5 main antigenic components reactive to IgE antibodies induced. These components at about 44-64 kDa position were considered to be an important candidate antigen for diagnosis of the mite-related allergy.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

A theory of free vibrations of discrete fractional order (FO) systems with a finite number of degrees of freedom (dof) is developed. A FO system with a finite number of dof is defined by means of three matrices: mass inertia, system rigidity and FO elements. By adopting a matrix formulation, a mathematical description of FO discrete system free vibrations is determined in the form of coupled fractional order differential equations (FODE). The corresponding solutions in analytical form, for the special case of the matrix of FO properties elements, are determined and expressed as a polynomial series along time. For the eigen characteristic numbers, the system eigen main coordinates and the independent eigen FO modes are determined. A generalized function of visoelastic creep FO dissipation of energy and generalized forces of system with no ideal visoelastic creep FO dissipation of energy for generalized coordinates are formulated. Extended Lagrange FODE of second kind, for FO system dynamics, are also introduced. Two examples of FO chain systems are analyzed and the corresponding eigen characteristic numbers determined. It is shown that the oscillatory phenomena of a FO mechanical chain have analogies to electrical FO circuits. A FO electrical resistor is introduced and its constitutive voltage–current is formulated. Also a function of thermal energy FO dissipation of a FO electrical relation is discussed.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The theory of fractional calculus goes back to the beginning of thr throry of differential calculus but its inherent complexity postponed the applications of the associated concepts. In the last decade the progress in the areas of chaos and fractals revealed subtle relationships with the fractional calculus leading to an increasing interest in the development of the new paradigm. In the area of automaticcontrol preliminary work has already been carried out but the proposed algorithms are restricted to the frequency domain. The paper discusses the design of fractional-order discrete-time controllers. The algorithms studied adopt the time domein, which makes them suited for z-transform analusis and discrete-time implementation. The performance of discrete-time fractional-order controllers with linear and non-linear systems is also investigated.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Recent embedded processor architectures containing multiple heterogeneous cores and non-coherent caches renewed attention to the use of Software Transactional Memory (STM) as a building block for developing parallel applications. STM promises to ease concurrent and parallel software development, but relies on the possibility of abort conflicting transactions to maintain data consistency, which in turns affects the execution time of tasks carrying transactions. Because of this fact the timing behaviour of the task set may not be predictable, thus it is crucial to limit the execution time overheads resulting from aborts. In this paper we formalise a FIFO-based algorithm to order the sequence of commits of concurrent transactions. Then, we propose and evaluate two non-preemptive and one SRP-based fully-preemptive scheduling strategies, in order to avoid transaction starvation.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The occurrence of seven pharmaceuticals and two metabolites belonging to non-steroidal anti-inflammatory drugs and analgesics therapeutic classes was studied in seawaters. A total of 101 samples covering fourteen beaches and five cities were evaluated in order to assess the spatial distribution of pharmaceuticals among north Portuguese coast. Seawaters were selected in order to embrace different bathing water quality (excellent, good and sufficient). Acetaminophen, ketoprofen and the metabolite hydroxyibuprofen were detected in all the seawater samples at maximum concentrations of 584, 89.7 and 287 ng L− 1, respectively. Carboxyibuprofen had the highest seawater concentration (1227 ng L− 1). The temporal distribution of the selected pharmaceuticals during the bathing season showed that, in general, higher concentrations were detected in August and September. The environmental risk posed by the pharmaceuticals detected in seawaters towards different trophic levels (fish, daphnids and algae) was also assessed. Only diclofenac showed hazard quotients above one for fish, representing a potential risk for aquatic organisms. These results were observed in seawaters classified as excellent bathing water. Additional data is needed in order to support the identification and prioritization of risks posed by pharmaceuticals in marine environment.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

In South Brazil the circulation of two HIV-1 subtypes with different characteristics represents an important scenario for the study of the impact of HIV-1 diversity on the evolution of the HIV-1 epidemic and AIDS disease. HIV-1 B, the predominant variant in industrialized countries and HIV-1 C, the most prevalent subtype in areas with rapid epidemic growth, are implicated in most infections. We evaluated blood samples from 128 antiretroviral (ARV) naïve patients recruited at entry to the largest HIV outpatient service in Porto Alegre. Based on partial pol region sequencing, HIV-1 C was observed in 29%, HIV-1 B in 22.6% and, the recently identified CRF31_BC, in 23.4% of 128 volunteers. Other variants were HIV-1 F in 10% and other mosaics in 5.5%. In order to evaluate the association of socio-behavioral characteristics and HIV-1 subtypes, interviews and laboratory evaluation were performed at entry. Our data suggest an established epidemic of the three major variants, without any evidence of partitioning in either of the subgroups analyzed. However, anal sex practices were associated with subtype B, which could indicate a greater transmissibility of non-B variants by vaginal intercourse. This study provides baseline information for epidemiologic surveillance of the changes of the molecular characteristics of HIV-1 epidemics in this region.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The last three decades have seen quite dramatic changes the way we modeled time dependent data. Linear processes have been in the center stage in modeling time series. As far as the second order properties are concerned, the theory and the methodology are very adequate.However, there are more and more evidences that linear models are not sufficiently flexible and rich enough for modeling purposes and that failure to account for non-linearities can be very misleading and have undesired consequences.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

BACKGROUND: The quantitation of serum HBeAg is not commonly used to monitor viral response to therapy in chronic hepatitis B. METHODS: In this study, 21 patients receiving varying therapies were followed and their viral response monitored by concomitant viral load and HBeAg quantitation in order to study the meaning and the kinetics of both parameters. RESULTS: It was possible to distinguish between three different patterns of viral response. The first was characterized by a simultaneous decrease in serum HBV DNA and HBeAg. The second pattern was characterized by a decrease in serum HBeAg but persistent detection of HBV DNA. The third pattern was characterized by undetectable HBV DNA with persistent HBeAg positivity, which points to a non-response (Pattern III-B) except when HBeAg levels showed a slow but steady drop, characterizing a "slow responder" patient (Pattern III-A). CONCLUSIONS: The first pattern is compatible with a viral response. A long-term HBeAg seropositivity with a slow and persistent decrease (Pattern III-A) is also compatible with a viral response and calls for a prolongation of anti-viral treatment.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

O empreendedorismo social é um campo que tem vindo a ganhar uma importância crescente nas sociedades atuais, sendo reconhecido como uma ferramenta útil na promoção do desenvolvimento sustentável. Como se trata de um campo emergente, apresenta-se ainda pouco explorado. Em Cabo Verde não existem ainda estudos sobre o tema, embora existam já algumas iniciativas de empreendedorismo social. A investigação foi desenvolvida de forma a responder ao objetivo de se conhecer qual o contributo que as Organizações Não Governamentais para o Desenvolvimento (ONGD) portuguesas têm dado para a sedimentação do empreendedorismo social em Cabo Verde. Assim, procurou-se apurar e analisar as ONGD que desenvolvem projetos em Cabo Verde, as áreas em que estas atuam para promoverem o desenvolvimento economico-social, os meios de financiamentos a que recorrem, as dificuldades encontradas no desenvolvimento das suas atividades, bem como compreender a razão que levou a que Cabo Verde fosse beneficiado com as ações dessas ONGD. Para conseguir atingir estas metas recorreu-se à metodologia qualitativa onde se fez uma análise exploratória e descritiva. A técnica utilizada para a recolha da informação primária foi a entrevista dirigida aos responsáveis de seis ONGD portuguesas que atuam em Cabo Verde, nomeadamente a Associação para a Cooperação Entre os Povos, a Associação de Defesa do Património de Mértola, Instituto Marquês de Valle Flôr, Meninos do Mundo, Terras Dentro e a Associação Raia Histórica. Os resultados deste estudo permitiram identificar que as ONGD portuguesas agem impulsionando o empreendedorismo social em Cabo Verde através da promoção do desenvolvimento integrado e sustentável, apoiado em parcerias estabelecidas com outras organizações locais caboverdeanas. Estes parceiros são atores chave que estão no terreno e possuem o conhecimento da realidade do país. Cabo Verde foi beneficiado pelos projetos por pertencer aos Países Africanos de Língua Oficial Portuguesa e/ou à Comunidade dos Países de Língua Portuguesa. Na obtenção de recursos, a maioria das ONGD portuguesas recorre a recursos em espécie e a voluntários portugueses, desempenhando estes o papel de formadores. A geração de valor social por parte destas entidades é feita muitas vezes de uma forma indireta, através da criação de valor económico que depois se repercute em valor social. Este valor social resulta da sua atuação em várias áreas como a saúde e segurança alimentar, desenvolvimento rural, meio ambiente, educação e formação profissional, emprego, economia alternativa ou microcrédito, pobreza e exclusão social, ambiente, habitação, promoção social e do turismo, capacitação e reforço institucional e coerência das políticas públicas para o desenvolvimento. Sendo Cabo Verde um arquipélago, as principais dificuldades encontradas pelas ONGD na sua atuação prende-se com a acessibilidade às ilhas devido à falta de transportes e meios de comunicação.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Several researchers have stated that parasites can alter the behavior of their hosts, in order to increase the transmission rate, principally when prey-predator relationships are a reliable way of infection transmission. The aim of this study was to verify the occurrence of changes in anxiety and short-term memory patterns in experimentally infected Mus musculus by Toxocara canis and/or Toxoplasma gondii. Forty male Mus musculus (Balb/c) eight-week-old were divided into four groups of 10 mice each. One group was infected with 300 eggs of Toxocara canis; a second group was submitted to infection with 10 cysts of Toxoplasma gondii; a third group was concomitantly infected with both parasites with the same inoculums and the last group was maintained without infection. The anxiety levels were evaluated using an elevated plus maze and an actometer; the short-term memory was determined by a two-way active avoidance equipment. The determination of anxiety levels were conducted 40 and 70 days after infection and the short-term memory was evaluated 140 days after infection. Mice chronically infected by Toxoplasma gondii showed impaired learning and short-term memory, but no significant differences were found in mice infected by Toxocara canis or concomitantly infected by Toxocara canis and Toxoplasma gondii when compared to non infected mice.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

SUMMARY Cestodes of the Bertiella genus are parasites of non-human primates found in Africa, Asia, Oceania and the Americas. Species Bertiella studeri and Bertiella mucronatacould, accidentally, infect human beings. The infection occurs from ingestion of mites from the Oribatida order containing cysticercoid larvae of the parasite. The objective of this report is to register the first case of human infection by Bertiella studeri in Brazil. Proglottids of the parasite, found in the stool sample of a two-and-a-half-year-old child, were fixed, stained and microscopically observed to evaluate its morphological characteristics. Eggs obtained from the proglottids were also studied. The gravid proglottids examined matched the description of the genus Bertiella. The eggs presented a round shape, with the average diameter of 43.7 µm, clearly showing the typical pyriform apparatus of B. studeri. The authors concluded that the child was infected with Bertiella studeri,based on Stunkard's (1940) description of the species. This is the fifth case of human Bertiellosis described in Brazil through morphometric analysis of the parasite, the third in Minas Gerais State and the first diagnosed case of Bertiella studeriin Brazil.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The occurrence of leprosy has decreased in the world but the perspective of its elimination has been questioned. A proposed control measure is the use of post-exposure chemoprophylaxis (PEP) among contacts, but there are still questions about its operational aspects. In this text we discuss the evidence available in literature, explain some concepts in epidemiology commonly used in the research on this topic, analyze the appropriateness of implementing PEP in the context of Brazil, and answer a set of key questions. We argue some points: (1) the number of contacts that need to receive PEP in order to prevent one additional case of disease is not easy to be generalized from the studies; (2) areas covered by the family health program are the priority settings where PEP could be implemented; (3) there is no need for a second dose; (4) risk for drug resistance seems to be very small; (5) the usefulness of a serological test to identify a higher risk group of individuals among contacts is questionable. Given that, we recommend that, if it is decided to start PEP in Brazil, it should start on a small scale and, as new evidence can be generated in terms of feasibility, sustainability and impact, it could move up a scale, or not, for a wider intervention.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Dissertation presented to obtain the PhD degree in Biology

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Dissertação Apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Ciências da Conservação, especialização em Pintura

Relevância:

30.00% 30.00%

Publicador:

Resumo:

ABSTRACT - It is the purpose of the present thesis to emphasize, through a series of examples, the need and value of appropriate pre-analysis of the impact of health care regulation. Specifically, the thesis presents three papers on the theme of regulation in different aspects of health care provision and financing. The first two consist of economic analyses of the impact of health care regulation and the third comprises the creation of an instrument for supporting economic analysis of health care regulation, namely in the field of evaluation of health care programs. The first paper develops a model of health plan competition and pricing in order to understand the dynamics of health plan entry and exit in the presence of switching costs and alternative health premium payment systems. We build an explicit model of death spirals, in which profitmaximizing competing health plans find it optimal to adopt a pattern of increasing relative prices culminating in health plan exit. We find the steady-state numerical solution for the price sequence and the plan’s optimal length of life through simulation and do some comparative statics. This allows us to show that using risk adjusted premiums and imposing price floors are effective at reducing death spirals and switching costs, while having employees pay a fixed share of the premium enhances death spirals and increases switching costs. Price regulation of pharmaceuticals is one of the cost control measures adopted by the Portuguese government, as in many European countries. When such regulation decreases the products’ real price over time, it may create an incentive for product turnover. Using panel data for the period of 1997 through 2003 on drug packages sold in Portuguese pharmacies, the second paper addresses the question of whether price control policies create an incentive for product withdrawal. Our work builds the product survival literature by accounting for unobservable product characteristics and heterogeneity among consumers when constructing quality, price control and competition indexes. These indexes are then used as covariates in a Cox proportional hazard model. We find that, indeed, price control measures increase the probability of exit, and that such effect is not verified in OTC market where no such price regulation measures exist. We also find quality to have a significant positive impact on product survival. In the third paper, we develop a microsimulation discrete events model (MSDEM) for costeffectiveness analysis of Human Immunodeficiency Virus treatment, simulating individual paths from antiretroviral therapy (ART) initiation to death. Four driving forces determine the course of events: CD4+ cell count, viral load resistance and adherence. A novel feature of the model with respect to the previous MSDEMs is that distributions of time to event depend on individuals’ characteristics and past history. Time to event was modeled using parametric survival analysis. Events modeled include: viral suppression, regimen switch due virological failure, regimen switch due to other reasons, resistance development, hospitalization, AIDS events, and death. Disease progression is structured according to therapy lines and the model is parameterized with cohort Portuguese observational data. An application of the model is presented comparing the cost-effectiveness ART initiation with two nucleoside analogue reverse transcriptase inhibitors (NRTI) plus one non-nucleoside reverse transcriptase inhibitor(NNRTI) to two NRTI plus boosted protease inhibitor (PI/r) in HIV- 1 infected individuals. We find 2NRTI+NNRTI to be a dominant strategy. Results predicted by the model reproduce those of the data used for parameterization and are in line with those published in the literature.