No description available.

The effect of temperature on predator and herbivore consumption is an important factor for predicting the effects of climate warming on ecosystems. The Metabolic Theory of Ecology (MTE) describes the temperature dependence of biological and ecological rates and states that metabolism is the fundamental biological mechanism that governs most observed patterns in ecology. This statement has been criticized empirically for a number of organismal traits and systematic deviations have been found. Here, a meta-analysis is performed on published temperature responses of ectotherm consumption. The mean effect of temperature on consumption was higher than the mean value predicted by proponents of the MTE and was highly variable. Some of this variation is explained by habitat type, where the consumption rates of marine organisms displayed stronger temperature dependence than for terrestrial and freshwater organisms. The frequency distribution of temperature dependencies is right skewed for consumption. Here, this skewness is explained by a methodological artefact as values close to “no effect” are more unlikely to be sampled than others when fitting the Arrhenius equation. In conclusion, the assumptions of the MTE do not hold for rates of consumption and marine organisms display a stronger temperature dependence compared to terrestrial and freshwater organisms.

Circadian rhythms are periodic physiological cycles that recur about every 24 hours, by means of which organisms integrate their physiology and behavior to the daily cycle of light and temperature imposed by the rotation of the earth. Circadian derives from the Latin word circa "about" and dies "day". Circadian rhythms have three noteworthy properties. They are endogenous, that is, they persist in the absence of external cues (in an environment of constant light intensity, temperature, etc.). Secondly, they are temperature compensated, that is, the nearly 24 hour period of the endogenous oscillator is remarkably independent of ambient temperature. Finally, they are phase shifted by light. The circadian rhythm can be either advanced or delayed by applying a pulse of light in constant darkness. Consequently, the circadian rhythm will synchronize to a periodic light-dark cycle, provided the period of the driving stimulus is not too far from the period of the endogenous rhythm. A window on the molecular mechanism of 24-hour rhythms was opened by the identification of circadian rhythm mutants and their cognate genes in Drosophila, Neurospora, and now in other organisms. Since Konopka and Benzer first discovered the period mutant in Drosophila in 1971 (Konopka and Benzer, 1971), there have been remarkable developments. Currently, the consensus opinion of molecular geneticists is that the 24-hour period arises from a negative feedback loop controlling the transcription of clock genes. However, a better understanding of this mechanism requires an approach that integrates both mathematical and molecular biology. From the recent discoveries in molecular biology and through a mathematical approach, we propose that the mechanism of circadian rhythm is based upon the combination of both negative and positive feedback. / Master of Science

Underground coal mine ground control persists as a unique challenge in rock mass engineering. Fall of roof and rib continue to present a hazard to underground personnel. Stability of underground openings is a prerequisite for successful underground coal mine workings. An adaptation of a civil engineering design standard for analyzing the stability of underground excavations for mining geometries is given here. The ground response curve--developed over seventy years ago for assessing tunnel stability--has significant implications for the design of underground excavations, but has seen little use in complex mining applications. The interaction between the small scale (pillar stress-strain) and the large scale (ground response curve) is studied. Further analysis between these two length scales is conducted to estimate the stress on pillars in a room-and-pillar coal mine. These studies are performed in FLAC3D by implementing a two-scale, two-step approach. This two-scale approach allows for the interaction between the small, pillar scale and the large, panel scale to be studied in a computationally efficient manner. / Ph. D.

Plantações clonais de eucalipto no Brasil apresentam as maiores médias de produtividade de madeira entre os principais países produtores. Dentre os fatores responsáveis por este êxito, estão as corretas práticas de manejo, em que as fertilizações minerais constituem uma das principais. Apesar de apresentar boas condições climáticas e atributos físicos do solo favoráveis, as florestas plantadas no Brasil necessitam de fertilizações com macro e micronutrientes. Na maioria dos solos e plantações florestais, as respostas são maiores para P e K, mas acredita-se que, devido às sucessivas rotações de produção e às elevadas quantidades de N exportadas, respostas às fertilizações nitrogenadas serão comuns em futuras rotações de cultivo. O objetivo deste estudo foi identificar as doses de N, P e K e fontes de N adequadas e a resposta à aplicação de Ca em plantações clonais de eucalipto e suas interações com fatores edafoclimáticos. Não apenas os teores nutricionais no solo, mas também os materiais genéticos e as condições climáticas influenciaram as respostas às fertilizações minerais. Em solos com teores entre baixo e médio de matéria orgânica e textura arenosa, foram verificadas respostas em produção de madeira entre 4 e 47% aos 60 meses para a aplicação das maiores doses de N. A ureia apresentou resultados de produção volumétrica de madeira próximos à dose equivalente de nitrato de amônio. A fertilização fosfatada proporcionou ganhos de produtividade em solos com teores de P-resina até 5 mg dm-3. Os ganhos em produtividade diminuíram com a idade dos povoamentos e, entre os 48 e 60 meses após o plantio, ficaram entre 14 e 19 %. Não houve influência climática ou do material genético associadas à fertilização fosfatada. Contrastando ao N e P, as respostas à fertilização potássica aumentaram com a idade em três dos quatro sítios estudados. Os ganhos de produtividade com a aplicação da maior dose de K ficaram entre 2 e 99% nas avaliações realizadas aos 48 e 60 meses após o plantio. Apesar dos teores do nutriente no solo serem considerados muito baixos para todos os locais, as respostas foram diferentes. Em Paulistânia, local com as maiores produtividades, as respostas à aplicação de K foram próximas a zero. O menor déficit hídico neste sítio foi identificado como fator mais influente. Para os três macronutrientes primários, os teores foliares diminuíram com a idade, e mesmo na ausência de respostas eles estiveram abaixo de teores foliares adequados. Não houve resposta à aplicação de Ca. / Clonal eucalyptus plantations in Brazil have the highest average productivity of wood amongst the main producing countries. Among those responsible for this success are the correct management practices, in which mineral fertilizations are a major. Despite showing good weather and favorable physical attributes of the soil, planted forests in Brazil require fertilization with macro and micronutrients. In most of the soils and forest plantations, responses are higher for phosphorus and potassium, but it is believed that due to successive rotations of production and high amounts of N exported, responses to nitrogen fertilization will be common in future rotations of cultivation. The aim of this study was to identify appropriate doses of N, P and K in clonal eucalyptus plantations and their interactions with edaphoclimatic factors. This study found that not only the nutritional content of the soil, but also the genetic materials and climatic conditions influence responses to mineral fertilization. In soils with low to medium organic matter levels and coarse texture responses between 4 and 47% were observed at 60 months, for the application of higher doses of N. Urea showed productivity responses close to the equivalent dose of ammonium nitrate. The P fertilization led to gains in productivity in soils with levels of P-resin up to 5 mg dm-3. Productivity gains evaluated decreased with age of the stands, and between 48 and 60 months after planting, were between 14 and 19%. There was no climate or genetic material linked to phosphorus fertilization influence. In contrast to N and P, the responses to potassium fertilization increased within age in three of the four studied sites. Productivity gains from the implementation of higher dose of K were between 2 and 99% in the assessments at 48 and 60 months after planting. Although the levels in the soil are considered very low for all sites, the answers were different. In Paulistânia, location with the highest yields, responses to K were close to 0. The smaller water deficit in this site was identified as the most influential factor to the results. For the three primary macronutrients, it was found that these foliar concentrations decreased with age, and that even in the absence of answers they were below levels recommended foliar elsewhere. There was no response to the application of Ca.

Sleep is essential for mammals and possibly for all animals. Advancing our knowledge of sleep regulation is crucial for the development of interventions in sleep-related health and social problems. With this aim, this study utilizes laboratory mice to explore sleep regulatory mechanisms at behavioral, molecular, and genetic levels. Sleep is regulated by the interaction of circadian and homeostatic processes. The circadian clock facilitates sleep to occur at a favorable time of the day. Normal mice, such as the C57BL/6J (B6) strain, sleep mostly during the day and initiate activities at dark onset. Here, I show mice of the CAST/EiJ (CAST) strain initiate activity unusually early (hours before dark). The circadian gating of photic phase-shifting responses was phase-lagged in the CAST mice relative to their activity rhythms, implying an altered coupling between the clock and its output. Light failed to suppress activity in the CAST mice, allowing full expression of the early activity. A previously identified quantitative trait locus that contributes to the advanced circadian phase was also confirmed and refined to a smaller genomic region. The circadian oscillation and light-induction of clock-genes Per1 and Per2 expression was not different between B6 and CAST mice in the suprachiasmatic nucleus (SCN) of the brain, where the mammalian master circadian clock is located. However, in the cerebral cortex and paraventricular hypothalamic nucleus of CAST mice, Per mRNA oscillations were phase-advanced coordinately with their advanced behavioral rhythms. These data thus provide direct evidence that the cause of the early runner phenotype is located downstream of the master circadian clock. The rhythms of cortical Per expression may not be a result of direct SCN effector mechanisms, but rather driven by activity-rest and sleep-wake. I further show that prolonged waking induces cortical Per expression, and this induction persisted in SCN-lesioned animals. SCN Per expression in intact animals was not affected. Thus, a homeostatic drive, independent of the SCN clock, regulates cortical Per expression, although a possible circadian influence in the intact animals was also suggested by detailed analyses. These data may suggest a molecular mechanism bridging the circadian and homeostatic processes for sleep regulation and functions.

There is a significant amount of computational literature on networks of neurons and their resulting behavior. This dissertation combines electrophysiology experiments with computational modeling to validate the assumptions and results found in this literature. First, we investigate the weak coupling assumption, which states that the phase response of a neuron to weak stimuli is separable from the stimulus waveform. For weak stimuli, there is an intrinsic neuronal property described by the infinitesimal phase response curve (IPRC) that will predict the phase response when convolved with the stimulus waveform. Here, we show that there is a linear relationship between the stimulus and phase response of the neuron, and that we are able to obtain IPRCs that successfully predict the neuronal phase response. Next, we use hybrid networks of neurons to study the phase locking behavior of networks as the synaptic time constant is changed. We verify that networks show anti-phase synchrony for fast time constants, and in-phase synchrony for slow time constants. We also show that phase models and phase response curves (PRCs) qualitatively predict phase locking observed in electrophysiology experiments. Finally, we investigate the stability of the dynamic clamp system. We determined that the maximal conductance of the current being simulated, the dynamic clamp sampling rate, the amount of electrode resistance compensation, and the amount of capacitance compensation all affect when the instability is present. There is a dramatic increase in stability when the electrode resistance and system capacitance are well compensated.

Plantações clonais de eucalipto no Brasil apresentam as maiores médias de produtividade de madeira entre os principais países produtores. Dentre os fatores responsáveis por este êxito, estão as corretas práticas de manejo, em que as fertilizações minerais constituem uma das principais. Apesar de apresentar boas condições climáticas e atributos físicos do solo favoráveis, as florestas plantadas no Brasil necessitam de fertilizações com macro e micronutrientes. Na maioria dos solos e plantações florestais, as respostas são maiores para P e K, mas acredita-se que, devido às sucessivas rotações de produção e às elevadas quantidades de N exportadas, respostas às fertilizações nitrogenadas serão comuns em futuras rotações de cultivo. O objetivo deste estudo foi identificar as doses de N, P e K e fontes de N adequadas e a resposta à aplicação de Ca em plantações clonais de eucalipto e suas interações com fatores edafoclimáticos. Não apenas os teores nutricionais no solo, mas também os materiais genéticos e as condições climáticas influenciaram as respostas às fertilizações minerais. Em solos com teores entre baixo e médio de matéria orgânica e textura arenosa, foram verificadas respostas em produção de madeira entre 4 e 47% aos 60 meses para a aplicação das maiores doses de N. A ureia apresentou resultados de produção volumétrica de madeira próximos à dose equivalente de nitrato de amônio. A fertilização fosfatada proporcionou ganhos de produtividade em solos com teores de P-resina até 5 mg dm-3. Os ganhos em produtividade diminuíram com a idade dos povoamentos e, entre os 48 e 60 meses após o plantio, ficaram entre 14 e 19 %. Não houve influência climática ou do material genético associadas à fertilização fosfatada. Contrastando ao N e P, as respostas à fertilização potássica aumentaram com a idade em três dos quatro sítios estudados. Os ganhos de produtividade com a aplicação da maior dose de K ficaram entre 2 e 99% nas avaliações realizadas aos 48 e 60 meses após o plantio. Apesar dos teores do nutriente no solo serem considerados muito baixos para todos os locais, as respostas foram diferentes. Em Paulistânia, local com as maiores produtividades, as respostas à aplicação de K foram próximas a zero. O menor déficit hídico neste sítio foi identificado como fator mais influente. Para os três macronutrientes primários, os teores foliares diminuíram com a idade, e mesmo na ausência de respostas eles estiveram abaixo de teores foliares adequados. Não houve resposta à aplicação de Ca. / Clonal eucalyptus plantations in Brazil have the highest average productivity of wood amongst the main producing countries. Among those responsible for this success are the correct management practices, in which mineral fertilizations are a major. Despite showing good weather and favorable physical attributes of the soil, planted forests in Brazil require fertilization with macro and micronutrients. In most of the soils and forest plantations, responses are higher for phosphorus and potassium, but it is believed that due to successive rotations of production and high amounts of N exported, responses to nitrogen fertilization will be common in future rotations of cultivation. The aim of this study was to identify appropriate doses of N, P and K in clonal eucalyptus plantations and their interactions with edaphoclimatic factors. This study found that not only the nutritional content of the soil, but also the genetic materials and climatic conditions influence responses to mineral fertilization. In soils with low to medium organic matter levels and coarse texture responses between 4 and 47% were observed at 60 months, for the application of higher doses of N. Urea showed productivity responses close to the equivalent dose of ammonium nitrate. The P fertilization led to gains in productivity in soils with levels of P-resin up to 5 mg dm-3. Productivity gains evaluated decreased with age of the stands, and between 48 and 60 months after planting, were between 14 and 19%. There was no climate or genetic material linked to phosphorus fertilization influence. In contrast to N and P, the responses to potassium fertilization increased within age in three of the four studied sites. Productivity gains from the implementation of higher dose of K were between 2 and 99% in the assessments at 48 and 60 months after planting. Although the levels in the soil are considered very low for all sites, the answers were different. In Paulistânia, location with the highest yields, responses to K were close to 0. The smaller water deficit in this site was identified as the most influential factor to the results. For the three primary macronutrients, it was found that these foliar concentrations decreased with age, and that even in the absence of answers they were below levels recommended foliar elsewhere. There was no response to the application of Ca.

This thesis proposes some new model independent or nonparametric methods for estimating the dose-response curve and the effective dosage curve in the context of bioassay. The research problem is also of importance in environmental risk assessment and other areas of health sciences. It is shown in the thesis that our new nonparametric methods while bearing optimal asymptotic properties also exhibit strong finite sample performance. Although our specific emphasis is on bioassay and environmental risk assessment, the methodology developed in this dissertation applies broadly to general order restricted inference.

On the protected horticultural industry, the artificial lighting is a common practice under reduced natural light radiation or self-shading of the leaves at lower canopies. Those conditions affect the photosynthetic activity and the yield is limited. In the last decade, the use of lamps with LED technology for supplemental lighting has increased on high-latitude countries. LED lights are more energy efficient and have lower power consumption. On these lamps is possible to regulate the intensity (quantity) and the radiation (quality) on the ideal range of light spectrum in order to convert the luminous energy into chemical energy. Not reports of use of this technology were found at the tropics. Thus, the objective of this work was to evaluate physiological parameters related with the photosynthetic activity and the yield on mini-cucumber plants grown on protected environment with supplemental LED interlighting. At Piracicaba (Sao Paulo), Brazil, three experiments were conducted on LED interlighting equipped greenhouse, two at winter seasons (2015 and 2016 years) and one at summer season (2017 year) using mini-cucumber hybrid Larino. Through the three stands, was verified an increase on the photosynthesis in the leaves and the commercial productivity of the mini-cucumber due to the LED lighting use. This increase on the commercial yield ranged between 13 and 30%, being higher the effect on the summer season. At the first stand, in addition to the light effect, grafted plants were tested. On this case, the photosynthetic rate increased with grafted plants when treated with LEDs. However, the yield did not increase with grafting. Postharvest parameters as titratable acidity, total soluble solids and long shelf life did not increase as consequence of supplemental LED lighting. Studying the light response curves, it was verified that above a photosynthetic photon flux density of 400 μmol m-2s-1, plants treated with supplemental lighting showed higher values of net CO2 assimilation. The light compensation point was also higher on plants with LEDs. In the case of the CO2 response curve, plants treated with LED lighting verified higher increase on the CO2 assimilation rate when the plant internal CO2 concentration increased. Parameters like Rubisco carboxylase activity, rate of electron transport and leaf dark respiration were also higher on plants under supplemental LED lighting. The lower consumption of electricity and the yield increase on the summer stand allowed registering greater energy and light efficiency on this cycle when compared with the winter stands. For the same reason, the cost analysis revealed that only at the summer stand the LED interlighting was profitable. At that time, the total net income was positive and the benefit cost ratio favorable (1.15). / Na produção hortícola em ambiente protegido, o emprego de luz artificial é uma prática comum, quando condições de radiação natural reduzidas ou o autosombreamento das folhas nos estratos médio e inferior do dossel prejudicam a atividade fotossintética da planta, e consequentemente, limitam a produtividade. Na última década, em países de alta latitude, tem aumentado o uso de lâmpadas com tecnologia de luz LED para fazer essa suplementação luminosa. As luzes do tipo LED são mais eficientes energeticamente e apresentam baixo consumo de energia. Também nessas lâmpadas é possível regular a intensidade (quantidade) e a radiação (qualidade) na faixa ideal do espectro de luz visível para a conversão da energia luminosa em energia química. Em países de clima tropical, experiências dessa natureza não estão reportadas. Assim, foi realizado este trabalho com o objetivo de avaliar parâmetros fisiológicos relacionados com a atividade fotossintética e a produtividade de minipepino cultivado em um ambiente protegido com suplementação luminosa de tipo LED. Em Piracicaba (SP), foram conduzidos três experimentos em casa de vegetação, sendo realizados no inverno (anos 2015 e 2016) e no verão (ano 2017), usando plantas de minipepino híbrido Larino. Foi constatado nos três ciclos aumento na fotossíntese da planta e na produção de pepino comercial devido ao emprego da luz LED. Esse aumento no rendimento comercial variou entre 13 e 30%, sendo maior o efeito no ciclo do verão. No primeiro ciclo além do efeito da luz LED, plantas enxertadas foram testadas. Nesse caso, as plantas enxertadas mostraram também aumento na taxa fotossintética quando submetidas à suplementação luminosa, porém a produtividade não aumentou com a enxertia. Parâmetros de pós-colheita como acidez titulável, teor de sólidos solúveis e vida de prateleira não aumentaram pela suplementação com LED. Estudando as curvas de resposta à luz foi constatado que acima de 400 μmol m-2s-1 na densidade do fluxo de fótons, as plantas com suplementação luminosa mostraram valores maiores na taxa de assimilação líquida de CO2. O ponto de compensação à luz também foi superior em plantas com LED. No caso da curva de resposta ao CO2, as plantas tratadas com luz LED mostraram maior incremento na taxa de assimilação de CO2 quando a concentração interna de CO2 na planta aumentou. Parâmetros como atividade da Rubisco carboxilase, taxa de transporte de elétrons e a respiração obscura foram também maiores em plantas sob luz LED. O menor consumo de eletricidade junto com o aumento na produtividade no ciclo de verão favoreceu maior eficiência no uso da energia e da luz nesse ciclo, quando comparado com os ciclos de inverno. Por esse mesmo motivo, a análise de custos revelou que a suplementação luminosa com luz LED somente foi benéfica no ciclo de verão. Nessa época, a renda líquida total foi positiva e a relação custo beneficio favorável (1.15).