Made available in DSpace on 2014-08-20T14:07:35Z (GMT). No. of bitstreams: 1 dissertacao_nixon_da_rosa_westendorff.pdf: 1164743 bytes, checksum: 0e98d540bb2c2b7a5450d35d0dfaf837 (MD5) Previous issue date: 2012-02-28 / Weeds are responsible for most part of the reduction in rice yield. The species Cyperus esculentus, a Cyperaceae plant, stands out by adaptation to the flooded environment. Little is known about the competitive ability of the specie rice and what is the extent of the economic loss caused. The economic thresholds (ET) has been an important tool to quantify weed damage to crops, in addition to supporting decision making of when the adoption of compensatory measure of control. The most obvious consequences of the use of ET in decision making are reduction of production costs, less use of herbicides and thereby benefitting the environment and man, and minimization of the selection pressure that select weeds resistant. The objectives of this research were to study the adaptive value, the competitive ability and the determination of ET for C. esculentus on flooded rice, using mathematical model for nonlinear regression derived from the rectangular hyperbolic, depending on the cycle of rice cultivars, irrigation timing and population of the weed. Studies were conducted for adaptation and competition in the field and greenhouse in the 2010/11 growing season. In general, the rice cultivars studied have superior adaptive value than C. esculentus. For rice, the intraspecific competition is more important, while for the weed interspecific competition is more pronounced. The hyperbolic model satisfactorily estimates the yield losses that C. esculentus causes in rice. The explanatory variable is the population of Cyperus esculentus that best fit the model. The reduction in the development cycle of rice cultivar and the anticipation of irrigation, increase the competitive potential of the culture and consequently increase the C. esculentus ET. / As plantas daninhas são responsáveis por grande parte da redução de produtividade das lavouras de arroz irrigado. A espécie Cyperus esculentus, pertencente à família Cyperaceae, destaca-se pela adaptação ao ambiente irrigado. Pouco se conhece sobre a habilidade competitiva da espécie com a cultura do arroz e qual é a dimensão do prejuízo econômico causado. O nível de dano econômico (NDE) tem sido importante ferramenta na quantificação de prejuízos às culturas, além de subsidiar a tomada de decisão de quando é compensatória a adoção de medida de controle. As vantagens mais evidentes do uso de NDE na tomada de decisão são diminuição dos custos de produção, menor uso de herbicidas e, com isso, menor contaminação do ambiente e do homem e minimização do processo de seleção que torna as plantas daninhas resistentes. Os objetivos dessa pesquisa foram o estudo do valor adaptativo, da habilidade competitiva e a determinação do NDE de C. esculentus na cultura do arroz irrigado, pelo uso do modelo matemático de regressão não linear derivado da hipérbole retangular, em função do ciclo das cultivares de arroz irrigado, época de irrigação e população da planta daninha. Para tal, foram conduzidos estudos de adaptação e competição a campo e em casa de vegetação no ano agrícola 2010/11. Em geral, as cultivares de arroz estudadas possuem valor adaptativo superior a C. esculentus. Para a cultura do arroz, a competição intraespecífica é mais importante, enquanto que para a planta daninha a competição interespecífica é a mais pronunciada. O modelo hiperbólico estima satisfatoriamente as perdas de produtividade que C. esculentus causa à cultura do arroz. A variável explicativa população de Cyperus esculentus é a que mais se ajustou ao modelo. A redução no ciclo de desenvolvimento da cultivar de arroz e a antecipação da irrigação incrementam o potencial competitivo da cultura e, consequentemente, aumentam os NDE de C. esculentus.

Thesis (PhD)--University of Pretoria, 2013. / Electrical, Electronic and Computer Engineering

Mathematical models provide unique insights to real-world problems. Within the context of infectious diseases, models are used to explore the dynamics of infections and control mechanisms. Human papillomavirus (HPV) globally infects about 630 million people, many of these infections develop into cancers and genital warts. Vaccines are available to protect against the most prevalent and devastating strains of HPV. The introduction of this vaccine as part of a national immunization program in Canada is a complex decision for policy-makers in which mathematical models can play a key role. We use the current recommendations provided by the World Health Organization to explore the integral role mathematical models have in the decision to incorporate the HPV vaccine within a national immunization program. We then provide a review of the literature discussing the role of mathematical models in the decision to include a vaccine in a national immunization program within the context of the HPV vaccine. Next, we evaluate the current standing of mathematical models used within the context of HPV immunization, to highlight the types of models used, underlying assumptions and general recommendations made about these immunization programs. Then, we create and analyze a model to explore the possibility of bettering the current HPV vaccine strategy in Canada. We focus on the effects of the grade of vaccination and the number of doses required to eradicate the targeted strains of HPV.

The aim of this work is to create a functional specification of mobile application newly emerging asocial network for generating meetings with friends. Generating will be divided into two phases. In the first phase, we will use a mathematical model which will generate appointments with those friends that the user meets the least. In the second phase, we will use a mathematical model and multi-criteria decision making process for invitation of maximum number of friends to this meeting. Using graph theory, we will develope an algorithm which will optimize the computing system over all its users. And finally, we will define functionality for meeting friends in partner establishments in the city, which will use the principle of finding the shortest path.

As pastagens são o principal recurso alimentar para pecuária brasileira, sendo fundamentais na viabilização dos sistemas produtivos. Fatores climáticos como temperatura e fotoperíodo têm grande importância no crescimento das plantas forrageiras, influenciando o acúmulo de forragem a distribuição estacional da produção e do valor nutritivo, fatores de grande impacto no sistema produtivo como um todo. Dessa forma, o desenvolvimento de ferramentas que racionalizem o processo produtivo das plantas possibilitando a sua predição em função dos parâmetros ambientais que o condicionam são importantes para o planejamento desses sistemas. O presente estudo foi desenvolvido no Departamento de Zootecnia da ESALQ/USP em Piracicaba, SP, de Dezembro de 2000 a Março de 2002, com o objetivo de gerar um banco de dados sobre as características produtivas e qualitativas de gramíneas forrageiras do gênero Cynodon e, a partir desse banco de dados, avaliar modelos matemáticos propostos na literatura para estimar o acúmulo de massa seca e as alterações no valor nutritivo [teores de proteína bruta (PB), fibra em detergente neutro (FDN), e a digestibilidade in vitro da matéria orgânica (DIVMO)] dessas forragens. Foram estudadas duas variáveis climáticas, uma gerada em função da soma térmica diária (graus-dia, GD), e outra incorporando os efeitos das alterações no fotoperíodo à soma térmica (a unidade fototérmica, UF). Os tratamentos constituiram de todas as combinações possíveis entre dois intervalos entre cortes (4 e 6 semanas) e cinco cultivares de Cynodon spp. (Tifton 85, Coastcross, Florico, Florona e Estrela) mecanicamente colhidos a 7 cm. As parcelas eram irrigadas para garantir ausência de déficit hídrico e adubadas com o equivalente a 400 kg N ha-1 ano-1. O delineamento experimental utilizado foi o de blocos completos casualizados com quatro repetições. Nas três estações de crescimento determinadas, "estação completa", "verão" e "inverno" foram avaliados o acúmulo de forragem (AF), a taxa média diária de acúmulo de forragem (TMDAF), a distribuição estacional da produção e os teores de PB e de FDN, além da DIVMO. O intervalo de seis semanas proporcionou maior AF, maior TMDAF, menor teor de PB, menor DIVMO e maior teor de FDN do que o intervalo de quatro semanas nas três "estações" consideradas. A distribuição estacional da produção foi igual para os dois intervalos, com 73% da produção no "verão" e 27% no "inverno". O AF e a TMDAF para a "estação completa" não foram diferentes entre os cultivares, mas no "verão" Tifton 85 foi superior a Coastcross e Florona. No "inverno", os cultivares não se diferenciaram nessas características, o que resultou em maior estacionalidade de produção de Tifton 85 do que de Coastcross, Florico e Florona. Coastcross apresentou os menores teores de PB e juntamente com Tifton 85 os maiores teores de FDN nas três"estações". A digestibilidade só foi diferente entre os cultivares na "estação completa", onde Florona superou Coastcross. Os modelos gerados para a resposta quantitativa (AF) foram altamente significativos, apresentando melhores resultados nos menores níveis de agregação. As duas variáveis climáticas foram eficientes, mas os modelos de UF apresentaram capacidade preditória superior. Os modelos para as respostas qualitativas também apresentaram alta significância, com melhores resultados nos maiores níveis de agregação. No entanto, em função da alta variabilidade tiveram sua capacidade preditória comprometida. Os cultivares estudados demonstraram significativas diferenças produtivas e qualitativas, que devem ser consideradas quando de sua adoção em sistemas produtivos. Nos intervalos entre cortes a produção e o valor nutritivo estiveram inversamente associados. A utilização de variáveis climáticas para a predição de parâmetros produtivos se mostrou efetiva em condições de ausência de déficit hídrico. Para a modelagem qualitativa o conceito se mostrou válido, mas novos modelos incluindo maior amplitude de maturidades da forragem devem ser gerados e avaliados. / Pastures are the main feed resource in the Brazilian livestock industry and they are key in making forage-livestock systems feasible. Climatic variables such as temperature and daylength are important to forage growth as they affect herbage accumulation as well as the seasonal distribution of both yield and nutritive value, two major characteristics that impact the systems as a whole. Thus, the development of manegerial tools that allow for the rationalization of the production process and for the prediction of forage responses to environmental variables may be valuable for planning and managing whole systems. The present study was carried out at the Departamento de Zootecnia of ESALQ-USP in Piracicaba, SP, from December 2000 through March 2002. The objective was to generate a comprehensive dataset on the productive and qualitative characteristics of Cynodon grasses and to use this dataset to evaluate prediction models reported in the literature, using them to estimate forage accumulation and changes in forage nutritive value [measured as concentrations of crude protein (CP) and neutral detergent fiber (NDF), as well as the in vitro organic matter digestibility (IVOMD)]. Two climatic variables were studied, one generated as a function of daily caloric sum (degree-days, DD) and the other combining the effect of daylength with DD and known as the photothermal unit (PU). Treatments included all possible combinations between two intervals between clippings (every four or six weeks) and five Cynodon spp. cultivars (Tifton 85, Coastcross, Florico, Florona e Stargrass) harvested mechanically at a 7-cm height. Plots were irrigated to ensure that soil moisture was not limiting at any point during the experiment and fertilized at the rate of 400 kg N ha-1 yr-1. The experimental design was a randomized complete block with four replications. For the three "seasons" established ("whole season", "summer", and "winter"), total herbage accumulation (HA), the mean daily HA rate (MDHAR), the seasonal yield distribution and the concentrations of CP and NDF plus the IVOMD of the forage produced were characterized. The 6-wk harvest interval resulted in higher HA and MDHAR, lower CP and IVOMD, and higher NDF than the 4-wk interval, for all three "seasons". Seasonal yield distribution was similar between intervals, with 73% of the total forage accumulating during the "summer" and 27% in the "winter". HA and MDHAR for the "whole season" was the same across cultivars but during the "summer", these responses were higher in Tifton 85 than on Coastcross and Stargrass. In the "winter", no differences were found across cultivars for these quantitative responses and this resulted in more pronounced seasonality for Tifton 85 than for Coastcross, Florico and Florona. Coastcross forage had the lowest CP concentration and, together with Tifton 85 forage, the highest NDF concentrations in all three "seasons". Forage IVOMD was the same across treatments except among cultivars in the "whole season", where Florona showed higher IVOMD than Coastcross. The prediction models generated for the quantitative response HA were highly significant and seem to be better predictors at lower aggregation levels. Both climatic variables were efficient, although the PU models had a better prediction ability than the DD models. For the qualitative characteristics were also significant, but with better results for the higher aggregation levels. Because of the high variability involved, however, their predictive ability may have been somewhat compromised. The grass cultivars used in this study have contrasting productive and qualitative characteristics, which must be taken into account when one considers their inclusion into the system. Within harvest intervals yield and nutritive value were inversely related. The use of climatic variables to predict forage quantitative responses appears to be promising in the absence of water deficit. For qualitative characteristics, the concept seems to hold although more modeling is needed using a wider range of forage maturities.

No description available.

Silicon Nanowire (SiNW) based reconfigurable fieldeffect transistors (RFETs) provide an additional gate terminal called the program gate which gives the freedom of programming p-type or n-type functionality for the same device at runtime. This enables the circuit designers to pack more functionality per computational unit. This saves processing costs as only one device type is required, and no doping and associated lithography steps are needed for this technology. In this paper, we present a complete design flow including both logic and physical synthesis for circuits based on SiNW RFETs. We propose layouts of logic gates, Liberty and LEF (Library Exchange Format) files to enable further research in the domain of these novel, functionally enhanced transistors. We show that in the first of its kind comparison, for these fully symmetrical reconfigurable transistors, the area after placement and routing for SiNW based circuits is 17% more than that of CMOS for MCNC benchmarks. Further, we discuss areas of improvement for obtaining better area results from the SiNW based RFETs from a fabrication and technology point of view. The future use of self-aligned techniques to structure two independent gates within a smaller pitch holds the promise of substantial area reduction.

In this paper, we consider devices, circuits, and systems comprised of transistors with integrated ferroelectrics. Said structures are actively being considered by various semiconductor manufacturers as they can address a large and unique design space. Transistors with integrated ferroelectrics could (i) enable a better switch (i.e., offer steeper subthreshold swings), (ii) are CMOS compatible, (iii) have multiple operating modes (i.e., I-V characteristics can also enable compact, 1-transistor, non-volatile storage elements, as well as analog synaptic behavior), and (iv) have been experimentally demonstrated (i.e., with respect to all of the aforementioned operating modes). These device-level characteristics offer unique opportunities at the circuit, architectural, and system-level, and are considered here from device, circuit/architecture, and foundry-level perspectives.

The HIV/AIDS epidemic and the COVID-19 pandemic have ruined many people's lives. Antiretroviral therapy (ART) has controlled the HIV/AIDS epidemic and COVID-19 vaccine is expected to ease confusion caused by the pandemic. However, the supply of health-resource falls far short of the demand in resource-constrained countries; thus, decision-making about resource allocation should be discussed. Botswana, as a resource-constrained country with a high prevalence of HIV, needs to construct its own framework for ART allocation. We propose an equitable framework for ART and COVID-19 vaccine allocation in Botswana based upon the egalitarian principle, which provides each individual has an equal chance of receiving them. We use a spatial mathematical model of treatment accessibility with an equity objective function, and sequential quadratic programming is used to address the nonlinear programming model. Considering Botswana's current health infrastructure, our strategy brings the most equal health outcomes. However, the disparity of accessibility still exists between rural and urban areas even from our equitable strategy. We present proposals that can increase the accessibility of rural areas using sensitivity analysis. Our work can be applied to different contexts, especially in sub-Saharan Africa.

This thesis deals with the numerical modeling of water overflow over the front spillway. The aim of the thesis is to calculate various types of turbulent models and to assess the overflow coefficient on a sharp front spillway. The model was created in free software SketchUp, but the modeling itself was carried out in FLOW-3D software. The content of the work is a description of used software, design and calculation.