3,408 research outputs found
The effects of temperature forcing on dengue dynamics via the extrinsic incubation period
Dengue fever is a mosquito-transmitted disease that is endemic in many parts of the tropical world and affects a significant proportion of the human population. Temperature is known to influence aspects of the dengue transmission cycle, which has consequences for disease dynamics. Previous work has explored the effects of temperature on the mortality rate of the mosquito and the resulting population change. However, there is substantial evidence that the extrinsic incubation period (EIP) of the pathogen within the vector host, Aedes aegypti, is also temperature dependent. This dependence has not been thoroughly researched. We present a single serotype compartmental model with a gamma-distributed exposed vector class to account for a temperature-dependent EIP. Where appropriate, temperature-dependent vector mortality is convolved with the temperature dependent EIP using the mortality function presented by Yang et al. [49]. Both seasonal and diurnal temperature changes are examined for their potential effects upon dengue persistence. The mean and range of temperature fluctuations that facilitate persistence are presented based upon the EIP function, initial conditions, seasonal temperature forcing with and without vector mortality, as well as seasonal and diurnal temperature forcing with and without vector mortality. With seasonal forcing and temperature dependence only in the EIP, all simulations with mean temperatures above 26 C show persistence. However, if vector mortality is also variable, persistence is no longer possible in higher temperatures with higher temperature ranges. Diurnal forcing exacerbates this effect limiting persistence to mean temperatures of 23 C to 34 C with variable temperature ranges. It is clear that more data are needed to reduce the uncertainty in estimating the relationships between both EIP and vector mortality because these relationships can have large effects on disease dynamics. Additionally, this work demonstrates that when modeling temperature-dependent effects, it is vital to not only include seasonal variation in temperature but also diurnal variation
Γ To Xz Electron Transfer Times In Type-ii Superlattices Due To Emission Of Confined Phonons
We calculate the Γ→Xz electron transfer times due to the emission of confined longitudinal optical phonons in type-II GaAs-AlAs and AlGaAs-AlAs superlattices. A dielectric continuum model is employed to describe the electron-confined-phonon interaction and the electron envelope wave functions are obtained from a Kronig-Penney model. The calculated transfer times compare within order of magnitude, or better, with available experimental results and we obtain a good qualitative description of the transfer time dependence on the layer thicknesses.65101281128
Choosing to Serve? An Exploration of Student Self-Selection of Service Learning Projects
This study explores student selection of service learning projects in lieu of traditional library research projects. One hundred fifty-four strategic management students completed surveys exploring their tolerance of ambiguity, time pressure, attitudes toward civic participation, self-efficacy toward service, political conservatism, and the role business school’s should play in civic education. The study examined their responses to survey questions in light of their project selection. The study identified factors important for faculty in designing and developing service learning projects as well as key areas for future research
The whatsappers’ turn: new forms of cyberactivism
Este artigo investiga como o uso das tecnologias da informação e comunicação (TIC’s), em particular, o WhatsApp, vem se apresentando como elemento central para a convocação e a mobilização de ciberativistas nas formas contemporâneas de participação política. A pesquisa verificou o potencial mobilizador do WhatsApp para além das abordagens dicotômicas que, por um lado, defendem entusiasticamente o potencial democratizador da internet como uma espécie de “ágora digital”, por outro, observam sua expansão como tendência à alienação e à desmobilização. Conclui-se, a partir da análise empírica, que os múltiplos usos do WhatsApp representaram novas formas de participação política traduzidas em mecanismos de ativação da cidadania e impacto positivo nas formas coletivas de sociabilidade do grupo.This article investigates how the use of Information and Communication Technologies (ICTs), in particular WhatsApp, has been presented as a central element for the convening and mobilization of cyberactivists in contemporary forms of political participation. For that, it was focused on how the users of the "# United against the coup" group organized protests in 2016 in the city of Florianópolis in Brazil, in what is commonly known as cyberactivism. The article verified the mobilizing potential of WhatsApp in addition to dichotomous approaches that, on the one hand, enthusiastically defend the democratizing potential of the internet as a sort of "digital agora", on the other, observe its expansion as a tendency towards alienation and demobilization. It is concluded from the empirical analysis that the multiple uses of WhatsApp represented new forms of political participation translated into mechanisms of activation of citizenship and positive impact on the collective forms of sociability of the groupMinisterio de Economía y Competitividad CSO2016-78386-
Role of Estrogen in Thyroid Function and Growth Regulation
Thyroid diseases are more prevalent in women, particularly between puberty and menopause. It is wellknown that estrogen (E) has indirect effects on the thyroid economy. Direct effects of this steroid hormone on thyroid cells have been described more recently; so, the aim of the present paper was to review the evidences of these effects on thyroid function and growth regulation, and its mechanisms. The expression and ratios of the two E receptors, α and β, that mediate the genomic effects of E on normal and abnormal thyroid tissue were also reviewed, as well as nongenomic, distinct molecular pathways. Several evidences support the hypothesis that E has a direct role in thyroid follicular cells; understanding its influence on the growth and function of the thyroid in normal and abnormal conditions can potentially provide new targets for the treatment of thyroid diseases
Prognosis of Thyroid Cancer Related to Pregnancy: A Systematic Review
Differentiated thyroid cancer (DTC) is the second most common cancer in pregnancy. Its management is a challenge for both doctors and patients, and the best timing for surgery is unclear. A systematic review evaluating the prognosis of DTC in pregnant patients was conducted. After reviewing 401 unique citations and 54 full texts, 4 studies that compared the prognosis of patients with DTC related to pregnancy (DTC diagnosed during pregnancy or within 12 months after childbirth) or not were included. In two studies the primary outcome was overall survival, in one study the primary outcomes were recurrent disease and death related to thyroid cancer, and in one study the primary outcome was recurrent or persistent disease. In the first two studies, there was no difference in overall survival in patients with pregnancy-related DTC, when compared with matched controls; in one study, there was no difference in death caused by DTC nor recurrence in DTC related to pregnancy. Nevertheless, in a recent retrospective study, a higher rate of recurrent or persistent DTC was observed in patients with DTC related to pregnancy. There are not many studies on which to base treatment decisions in pregnant patients with DTC
Planejamento Tributário: uma escolha entre as modalidades de tributação - Lucro Presumido e SIMPLES
TCC (Graduação) - Universidade Federal de Santa Catarina. Centro Socioeconômico. Curso de Ciências ContábeisO trabalho objetiva analisar e identificar a melhor modalidade de tributação para uma empresa do ramo de comércio e manutenção de produtos para telecomunicações. A problemática a ser resolvida nesta pesquisa é descobrir qual destas modalidades deve ser adotada na apuração de seus impostos. Para alcançar este objetivo fez-se necessário a construção de três objetivos específicos: caracterizar o planejamento estratégico, com ênfase no planejamento tributário; descrever os principais aspectos das modalidades de tributação existentes; e evidenciar, por meio do planejamento tributário, as vantagens e desvantagens pertinentes a cada uma delas. Trata-se de um estudo bibliográfico, que utiliza da pesquisa documental como tipologia da pesquisa e os dados coletados foram tratados de forma qualitativa. Buscou-se realizar, por meio de um planejamento tributário, uma comparação entre as modalidades de tributação lucro presumido e SIMPLES, tendo como meta verificar qual delas apresenta ser mais condizente com a realidade da empresa. Os dados necessários à realização desta pesquisa foram coletados no escritório contábil em que a empresa é cliente, por meio das notas fiscais emitidas de vendas e prestação de serviços durante o ano de 2006. A partir disso, realizaramse cálculos com a intenção de verificar os valores apurados de cada uma das modalidades estudadas. A análise feita permitiu observar a importância da aplicação do planejamento tributário como suporte informacional disponibilizado pela contabilidade, tendo em vista orientar os usuários de que é possível reduzir os gastos com tributos dentro da legalidade
Effects of Market Reform on Access to Food by Low-Income Households: Evidence from Four Countries in Eastern and Southern Africa
Food Consumption/Nutrition/Food Safety, Downloads June 2008 - June 2009: 10,
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