O milho (Zea mays) é considerado como uma das culturas mais importantes cultivadas mundialmente devido a sua composição química, valor nutritivo e o seu potencial produtivo, apresentando assim, considerável relevância nos aspectos socioeconômicos. Diversos fatores interferem no desempenho da cultura e, dentre eles, o clima está entre aqueles que oferecem os maiores desafios para planejamento e manejo da cultura. Diante da importância da cultura no contexto nacional e mundial, é importante considerar as projeções futuras da produção do grão diante das mudanças climáticas e, consequentemente, na segurança alimentar nos próximos anos. Assim, avaliou-se neste estudo o impacto da mudança do clima sobre o crescimento e desenvolvimento da cultura do milho, utilizando um modelo de crescimento de plantas, baseado em processos biofísicos. Para a calibração do modelo foram utilizados dados obtidos experimentalmente e a simulação de cenários de mudanças climáticas foi realizada de acordo com a abordagem do programa AgMIP. Trabalhou-se com o modelo CERES-MAIZE/DSSAT, e três modelos de circulação climática global (GCM\'s) regionalizados e dois cenários econômicos (ou de emissão) para o período 2040-2069 (representando 2050). Com base nos resultados obtidos, pode-se concluir que se as práticas de gestão se mantêm como presentes, o rendimento de milho deverá diminuir em meio do século, no entanto, a diminuição dos rendimentos reais pode não ser tão dramática quanto previsto nos casos em que apenas o fator climático é considerado. Para isso fatores econômicos e tecnológicos devem ser considerados para aumentar os rendimentos. O aumento da [CO2] terá um efeito positivo sobre o crescimento do cultivo, mas não parece ser suficiente para compensar os efeitos negativos do clima futuro, notadamente o aumento da temperatura do ar. / Maize (Zea mays) is considered one of the most important crops cultivated worldwide due to its chemical composition, nutritional value and its productive potential, thus presenting considerable relevance in socioeconomic aspects. Several factors interfere in the performance of the crop and, among them, the climate is among those that offer the greatest challenges for crop planning and management. Given the importance of culture in the national and global context, it is important to consider the future projections of grain production in the face of climate change and, consequently, food security in the coming years. Thus, the impact of climate change on maize crop growth and development was evaluated in this study using a plant growth model based on biophysical processes. For the calibration of the model, data obtained experimentally were used and the simulation of climate change scenarios was performed according to the AgMIP program approach. We worked with the CERES-MAIZE / DSSAT model, and three regional climate circulation models (GCM\'s) and two economic (or emission) scenarios for the period 2040-2069 (representing 2050). Based on the results obtained, it can be concluded that if management practices remain as present, corn yields should decrease in the middle of the century, however, the decrease in real incomes may not be as dramatic as predicted in cases where that only the climatic factor is considered. For this economic and technological factors must be considered to increase incomes. The increase in [CO2] will have a positive effect on crop growth, but it does not appear to be sufficient to compensate for the negative effects of future climate, notably the increase in air temperature.

O milho (Zea mays) é considerado como uma das culturas mais importantes cultivadas mundialmente devido a sua composição química, valor nutritivo e o seu potencial produtivo, apresentando assim, considerável relevância nos aspectos socioeconômicos. Diversos fatores interferem no desempenho da cultura e, dentre eles, o clima está entre aqueles que oferecem os maiores desafios para planejamento e manejo da cultura. Diante da importância da cultura no contexto nacional e mundial, é importante considerar as projeções futuras da produção do grão diante das mudanças climáticas e, consequentemente, na segurança alimentar nos próximos anos. Assim, avaliou-se neste estudo o impacto da mudança do clima sobre o crescimento e desenvolvimento da cultura do milho, utilizando um modelo de crescimento de plantas, baseado em processos biofísicos. Para a calibração do modelo foram utilizados dados obtidos experimentalmente e a simulação de cenários de mudanças climáticas foi realizada de acordo com a abordagem do programa AgMIP. Trabalhou-se com o modelo CERES-MAIZE/DSSAT, e três modelos de circulação climática global (GCM\'s) regionalizados e dois cenários econômicos (ou de emissão) para o período 2040-2069 (representando 2050). Com base nos resultados obtidos, pode-se concluir que se as práticas de gestão se mantêm como presentes, o rendimento de milho deverá diminuir em meio do século, no entanto, a diminuição dos rendimentos reais pode não ser tão dramática quanto previsto nos casos em que apenas o fator climático é considerado. Para isso fatores econômicos e tecnológicos devem ser considerados para aumentar os rendimentos. O aumento da [CO2] terá um efeito positivo sobre o crescimento do cultivo, mas não parece ser suficiente para compensar os efeitos negativos do clima futuro, notadamente o aumento da temperatura do ar. / Maize (Zea mays) is considered one of the most important crops cultivated worldwide due to its chemical composition, nutritional value and its productive potential, thus presenting considerable relevance in socioeconomic aspects. Several factors interfere in the performance of the crop and, among them, the climate is among those that offer the greatest challenges for crop planning and management. Given the importance of culture in the national and global context, it is important to consider the future projections of grain production in the face of climate change and, consequently, food security in the coming years. Thus, the impact of climate change on maize crop growth and development was evaluated in this study using a plant growth model based on biophysical processes. For the calibration of the model, data obtained experimentally were used and the simulation of climate change scenarios was performed according to the AgMIP program approach. We worked with the CERES-MAIZE / DSSAT model, and three regional climate circulation models (GCM\'s) and two economic (or emission) scenarios for the period 2040-2069 (representing 2050). Based on the results obtained, it can be concluded that if management practices remain as present, corn yields should decrease in the middle of the century, however, the decrease in real incomes may not be as dramatic as predicted in cases where that only the climatic factor is considered. For this economic and technological factors must be considered to increase incomes. The increase in [CO2] will have a positive effect on crop growth, but it does not appear to be sufficient to compensate for the negative effects of future climate, notably the increase in air temperature.

The emphasis of this study will be centered in the search for answers to the following questions: (1) How accurately and extensively do adults of the community know their elementary schools?; (2) What are the various sources by which adults of the community receive school information?; (3) What types (categories) of school information for citizens desire most?; (4) What types of school news items appear most frequently in the local newspaper, and how accurate and effective in it? The objective in conducting this study is to gain an insight into the matter of communication between the elementary school and the community and to evaluate local school publicity.

No description available.

No description available.

Ahuna Mons is a 4 km tall mountain on Ceres interpreted as a geologically young cryovolcanic dome. Other possible cryovolcanic features are more ambiguous, implying that cryovolcanism is only a recent phenomenon or that other cryovolcanic structures have been modified beyond easy identification. We test the hypothesis that Cerean cryovolcanic domes viscously relax, precluding ancient domes from recognition. We use numerical models to predict flow velocities of Ahuna Mons to be 10-500 m/Myr, depending upon assumptions about ice content, rheology, grain size, and thermal parameters. Slower flow rates in this range are sufficiently fast to induce extensive relaxation of cryovolcanic structures over 10(8)-10(9) years, but gradual enough for Ahuna Mons to remain identifiable today. Positive topographic features, including a tholus underlying Ahuna Mons, may represent relaxed cryovolcanic structures. A composition for Ahuna Mons of >40% ice explains the observed distribution of cryovolcanic structures because viscous relaxation renders old cryovolcanoes unrecognizable.

Magister Artium - MA / In studies oor die swart Afrikaanse amateur gemeenskapsteater is voorheen beweer dat die platteland geen oorspronklike en noemenswaardige bydra gelewer het nie. Hiedie studie rig hom op aktiwiteite van hierdie aard in die Wolseley/CereslW oreester-area en bewys dié soort aannames verkeerd. Die swart Afrikaanse gemeenskapsteater van die area word hier beskryf gedokumenteer, maar terselfdertyd ook vergelyk met dit wat op dieselfde terrein in die stedelike gebiede van die Skiereiland plaasgevind het. Laasgenoemde was in die apartheidsjare meer dikwels openlik deel van die bevrydingstryd. Dit teenoor die meer sisteembevestigende aktiwiteite op die platteland. Oorsake hiervoor was onder meer die greep van die kerk op sy lidmate asook ook pogings om die gemeenskap van Ceres en omstreke op te beur ná die vernietigend aardbewing van 1969. Ook die verliese ná gedwonge verskuiwing ingevolge die Groepsgebiedewet is deur dié soort vermaak besweer. Hierteenoor het die middel jare tagtig 'n nuwe, militante generasie leerders op die verhoog gebring. Uit hulle het die streek se eerste anti-hegemoniese dramagroep voortgekom. Hulle het gesorg vir hulle eie treffende sisteem- kritiese drama. Hulle het ook grootliks bygedra om die gemeenskappe in die Boland en Karoo politiek bewus te maak. Die studie wil hierdie gemarginaliseerde teatergebeure aan die vergetelheid ontruk en so 'n bydra lewer tot 'n ewewigtiger Suid-Afrikaanse kultuurgeskiedenis. / South Africa

No description available.

NASA's Clouds and the Earth's Radiant Energy System (CERES) program is a key component of the Earth Observing System (EOS). The CERES Proto-Flight Model (PFM) instrument is to be launched on NASA's Tropical Rainfall Measuring Mission (TRMM) spacecraft in November, 1997. Each CERES instrument will contain three scanning thermistor bolometer radiometers to monitor the longwave, 5.0 to >100 microns, and shortwave, 0.3 to 5.0 microns, components of the Earth's radiative energy budget. High-level, first-principle dynamic electrothermal models of the CERES radiometric channels have been completed under NASA sponsorship. These first-principle models consist of optical, thermal and electrical modules. Optical characterization of the channels is ensured by Monte-Carlo-based ray-traces. Accurate thermal and electrical characterization is assured by transient finite-difference formulations. This body of research presents the evolution of these models by outlining their development and validation. Validation of the models is accomplished by simulating the ground calibration process of the actual instruments and verifying that the models accurately predict instrument performance. The result of this agreement is a high confidence in the model to predict other aspects of instrument performance. / Ph. D.

The current effort addresses two issues important to the research conducted by the Thermal Radiation Group at Virginia Tech. The first research topic involves the development of a method which can properly model the diffraction of radiation as it enters an instrument aperture. The second topic involves the study of a potential next-generation space-borne radiometric instrument concept. Presented are multiple modeling efforts to describe the diffraction of monochromatic radiant energy passing through an aperture for use in the Monte-Carlo ray-trace environment. Described in detail is a deterministic model based upon Heisenberg's uncertainty principle and the particle theory of light. This method is applicable to either Fraunhofer or Fresnel diffraction situations, but is incapable of predicting the secondary fringes in a diffraction pattern. Also presented is a second diffraction model, based on the Huygens-Fresnel principle with a correcting obliquity factor. This model is useful for predicting Fraunhofer diffraction, and can predict the secondary fringes because it keeps track of phase. NASA is planning for the next-generation of instruments to follow CERES (Clouds and the Earth's Radiant Energy System), an instrument which measures components of the Earth's radiant energy budget in three spectral bands. A potential next-generation concept involves modification of the current CERES instrument to measure in a larger number of wavelength bands. This increased spectral partitioning would be achieved by the addition of filters and detectors to the current CERES geometry. The capacity of the CERES telescope to serve for this purpose is addressed in this thesis. / Master of Science