Dissertations / Theses on the topic 'Rich light'

This work mainly focuses on signal processing issues related to continuous-wave, polarization-based direct imaging schemes. Here, we present a mathematical framework to analyze the performance of the Polarization Difference Imaging (PDI) and Polarization Modulation Imaging (PMI). We have considered three visualization parameters, namely, the polarization intensity (PI), Degree of Linear Polarization (DOLP) and polarization orientation (PO) for comparing these schemes. The first two parameters appear frequently in literature, possibly under different names. The last parameter, polarization orientation, has been introduced and elaborated in this thesis. We have also proposed some extensions/alternatives for the existing imaging and processing schemes and analyzed their advantages. Theoretically and through Monte-Carlo simulations, we have studied the performance of these schemes under white and coloured noise conditions, concluding that, in general, the PMI gives better estimates of all the parameters. Experimental results corroborate our theoretical arguments. PMI is shown to give asymptotically efficient estimates of these parameters, whereas PDI is shown to give biased estimates of the first two and is also shown to be incapable of estimating PO. Moreover, it is shown that PDI is a particular case of PMI. The property of PDI, that it can yield estimates at lower variances has been recognized as its major strength. We have also shown that the three visualization parameters can be fused to form a colour image, giving a holistic view of the scene. We report the advantages of analyzing chunks of data and bootstrapped data under various circumstances. Experiments were conducted to image objects through calibrated scattering media and natural media like mist, with successful results. Scattering media prepared with polystyrene microspheres of diameters 2.97m, 0.06m and 0.13m dispersed in water were used in our experiments. An intensified charge coupled device (CCD) camera was used to capture the images. Results showed that imaging could be performed beyond optical thickness of 40, for particles with 0.13m diameter. For larger particles, the depth to which we could image was much lesser. An experiment using an incoherent source yielded better results than with coherent sources, which we attribute to the speckle noise induced by coherent sources. We have suggested a harmonic based imaging scheme, which can perhaps be used when we have a mixture of scattering particles. We have also briefly touched upon the possible post processing that can be performed on the obtained results, and as an example, shown segmentation based on a PO imaging result.

An experiment was conducted at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, using the R³B experimental setup. This included an array of double sided silicon strip detectors and a 4π array of NaI scintillator detectors surrounding the target, a bending magnet and downstream fragment detectors consisting of scintillating fibre detectors and a plastic scintillator time of flight wall. Cross sections have been measured for the breakup of ^{7,9-12}Be and ^{8,10-15}B on proton and \(^↔\)C targets at beam energies between 260 and 540 MeV per nucleon. These cross sections have been analysed with a focus on comparison to cluster model theory. In the context of a large collaboration and an experiment with diverse physics objectives, it is worth clarifying the author's contribution to the work presented. The author participated in running the experiment, calibrated the Silicon Strip Detectors and performed all the analysis discussed in this thesis.

The work presented in this thesis is concerned with investigating the use of UV-rich light pulses for the inactivation of problematic microorganisms. UV radiation is an effective means of disinfecting surfaces and liquids and of reducing contamination in air. The germicidal effects are primarily due to the UV-C region of the electromagnetic spectrum, which interferes with the nuclear core of a microorganism resulting in a loss of ability to replicate and initiate infection. When UV radiation is delivered as pulses of light however, the results are even more appealing, with higher levels of microbial inactivation achieved in much shorter timescales. Drinking water and wastewater disinfection is normally provided by the use of chemicals such as chlorine. These are disadvantaged by the production of harmful chemical by-products and the resistance of certain types of microorganism to chemical treatment. The main aim of this investigation was therefore to look at the role of pulsed UV-rich light for inactivating a range of microorganisms suspended in liquid media and to determine how successful the treatment process would be as an alternative disinfection method. The results show that pulsed UV-rich light treatment is extremely effective against many types of bacteria, virus and Cryptosporidium. It was also demonstrated that the sensitivities of microorganisms to UV radiation can vary significantly depending on the cell-wall structure, growth phase, strains and nucroorgarusm specIes. Studies were also undertaken to identify electrical and biological parameters that may influence the inactivation success. It was found that high operating voltages and low pulse repetition frequencies give desirable levels of inactivation Other important factors investigated were sample depth, volume and reflection. Finally, the possible limitations to pulsed UV-rich light treatment were investigated. It was found that the success of the treatment is primarily determined by the transmittance of UV pulses through a sample. As expected, transmittance depends upon microorganism size and population. The major limitation of UV treatment is the ability of microorganisms to reactivate following exposure to visible light (photoreactivation). Studies showed photoreactivation to occur following pulsed UV-rich light treatment, only when the microorganisms do not receive sufficient UV treatment or if they are exposed to high intensities of visible light.

We present the first scattered-light images of the debris disk around 49 Ceti, a similar to 40 Myr A1 main-sequence star at 59 pc, famous for hosting two massive dust belts as well as large quantities of atomic and molecular gas. The outer disk is revealed in reprocessed archival Hubble Space Telescope NICMOS-F110W images, as well as new coronagraphic H-band images from the Very Large Telescope SPHERE instrument. The disk extends from 1 1 (65 au) to 4.'' 6 (250 au) and is seen at an inclination of 73 degrees, which refines previous measurements at lower angular resolution. We also report no companion detection larger than 3 M-Jup at projected separations beyond 20 au from the star (0.'' 34). Comparison between the F110W and H-band images is consistent with a gray color of 49 Ceti's dust, indicating grains larger than greater than or similar to 2 mu m. Our photometric measurements indicate a scattering efficiency/infrared excess ratio of 0.2-0.4, relatively low compared to other characterized debris disks. We find that 49 Ceti presents morphological and scattering properties very similar to the gas-rich HD 131835 system. From our constraint on the disk inclination we find that the atomic gas previously detected in absorption must extend to the inner disk, and that the latter must be depleted of CO gas. Building on previous studies, we propose a schematic view of the system describing the dust and gas structure around 49 Ceti and hypothetical scenarios for the gas nature and origin.

En esta tesis, capas de óxido de silicio rico en silicio [SRO, (SiOx, x<2)] con diferentes excesos de silicio fueron depositadas por medio de la técnica de depósito químico en fase vapor a baja presión (LPCVD). Un segundo conjunto de muestras de SRO implantadas con silicio (SI-SRO) adicional fueron también fabricadas. Nanopartículas de silicio (Si-nps) en estas capas fueron creadas después de someter a las muestras a un tratamiento térmico en alta temperatura (1100 y 1250º C). La composición, microestructura y propiedades ópticas de estas capas de SRO y SI-SRO fueron analizadas en función de los diferentes parámetros tecnológicos, tales como exceso de silicio, implantación de silicio, así como de la temperatura de tratamiento térmico.
Una vez conocido la microestructura, composición y propiedades ópticas de estos materiales, capas de SRO que exhibieron la mejor propiedad fotoluminiscente (FL más intensa) fueron escogidas para analizar sus propiedades eléctricas y electro-ópticas; estructuras Metal-Óxido-Semiconductor (MOS) fueron fabricadas usando las capas de SRO como material dieléctrico para tales estudios. Capas de SRO con exceso de silicio de ~4.0 and ~2.2 at.% y grosores de entre 24 y 80 nm fueron depositadas. El mecanismo de conducción en estas películas es analizado haciendo uso de modelos como tuneleo asistido por trampas (TAT) y tuneleo Fowler-Nordheim (FN) en bajos y altos campos eléctricos, respectivamente.
Las mediciones eléctricas mostraron importantes resultados tales como una reducción en la capacitancia y corriente durante el barrido de voltaje o después de estresar eléctricamente los dispositivos. Dichos efectos son relacionados con la aniquilación de caminos conductivos que son creados por nanoclusters de silicio (Si-cls) que se encuentran dispersados dentro de la película de SRO.
Además de lo anterior, algunos dispositivos exhibieron fluctuaciones en la corriente en la forma de picos y un comportamiento de escalera muy claro a temperatura ambiente. Dichos efectos son relacionados con los llamados efectos de bloqueo Coulómbico (CB) que se presentan en las nanopartículas de silicio que se encuentran dentro de las capas de SRO. A partir del ancho de cada escalón se pudo estimar el tamaño (cerca de 1 nm) de las nanopartículas.
Estudios de luminiscencia de efecto de campo en las capas de SRO son estudiados por excitar los dispositivos con pulsos de voltaje. Además de la electroluminiscencia (EL) pulsada, es mostrado que estos dispositivos también muestran EL en voltaje continuo, donde la emisión es observada como múltiples puntos brillantes de varios colores sobre la superficie de los dispositivos cuando estos son polarizados en inversa. El espectro de emisión en dichos dispositivos es amplio y va desde 400 hasta 900 nm.
Finalmente, una correlación entre las propiedades microestructurales, eléctricas y luminiscentes (FL y EL) es analizada y discutida.
In this thesis, silicon rich oxide [SRO, (SiOx, x<2)] films with different silicon excesses were deposited by low pressure chemical vapor deposition (LPVCD). Besides, Si implanted SRO (SI-SRO) films were also fabricated. Si-nps in these films were created after a thermal annealing at high temperature (1100 and 1250º C). The composition, microstructure and optical properties of these SRO and SI-SRO films were analyzed as a function of the different technological parameters, such as silicon excess, Si ion implantation dose, and thermal annealing temperature.
Once the microstructure, composition as well as the optical properties of these materials is known, SRO films which exhibited the best photoluminescent (strongest PL) properties were chosen in order to analyze their electrical and electro-optical properties.
Simple Metal-Oxide-Semiconductor (MOS) structures using the SRO films as the dielectric layer were fabricated for these studies. SRO films with Si-excess of ~4.0 and ~2.2 at.% and thickness ranging from 24 to 80 nm were deposited. The conduction mechanism in these films is analyzed by making use of trap assisted tunnelling (TAT) in low electric field as well as Fowler-Nordheim (FN) tunnelling in high electric fields.
The electrical measurements exhibited important results, such as a reduction in capacitance and current during the sweep or after applying a constant bias. These effects are ascribed to the annihilation of conduction paths created by silicon clusters (Si-cls) inside the SRO films.
A part from that, some devices exhibited current fluctuations in the form of spike-like peaks and a clear staircase at room temperature. These effects were related to Coulomb blockade (CB) effects in the silicon nanoparticles embedded in the SRO films. And from the current plateaus, the size of the Si-nps (about 1 nm) was calculated.
Field effect luminescence of these SRO films was studied by alternating negative (positive) to positive (negative) voltages (pulsed excitation). Moreover, it is demonstrated that these SRO films show EL emission in continuous current voltage, observed at naked eye. Multiple shining spots of several colours are seen on the MOS-like structure surface when reversely biased. These devices display a broad electroluminescent emission spectrum which goes from 400 nm up to 900 nm.
Finally, a correlation between the structural, electrical and luminescent (PL and EL) properties is discussed.

Thesis (Ph. D.) -- University of Maryland, College Park, 2006.
Thesis research directed by: American Studies. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Northern peatlands are a globally important soil carbon (C) store, and aquatic systems draining peatland catchments receive a high loading of dissolved and particulate forms of C from the surrounding terrestrial environment. Once incorporated into the aquatic environment, internal processes occur to modify the C pool. Of these, photo-processing preferentially targets terrestrially derived C and therefore might have a significant effect on the C budget of peatland draining aquatic systems. The overarching aim of this study was to investigate photochemical processing of C in Scottish peatland draining aquatic systems in order to determine the importance of this pathway in aquatic biogeochemical cycles. For initial laboratory experiments, water samples from a peatland headwater stream (Auchencorth Moss, SE Scotland) were collected. Laboratory based irradiation experiments were conducted at a range of temperatures, and different filtration treatments, including unfiltered samples, were employed to understand the fraction of C most susceptible to photo-processing. UV irradiation and temperature had a significant effect on DOC and gas headspace concentrations, with Q10 values of ~1.42 and ~1.65 derived for CO2 and CO photoproduction in unfiltered samples, respectively. However, filtration treatment did not induce significant changes in gaseous C production between light and dark samples, indicating that the experimental conditions favoured breakdown of DOC rather than POC to CO2 and CO. In all light treatments a small but significant increase in CH4 concentration was detected. These data were compared to results from experiments conducted in ambient light and temperature conditions. DOC normalised CO2 photoproduction was an order of magnitude lower than in laboratory conditions, although relative abundances of C species within overall budgets were similar and these experiments demonstrated that ambient exposure is sufficient to generate photo-processing of aquatic peatland C. Overall these data show that peatland C, particularly the < 0.2 μm fraction, is highly photoreactive and that this process is temperature sensitive. Further laboratory irradiation experiments were conducted on filtered water samples collected over a 13-month period from two contrasting aquatic systems. The first was the headwater stream draining Auchencorth Moss peatland with high DOC concentrations. The second was a low DOC reservoir (Loch Katrine, C Scotland) situated in a catchment with a high percentage peat cover. Samples were collected monthly from May 2014 to May 2015 and from the stream system during two rainfall events. Significant variation was seen in the photochemical reactivity of DOC between the two systems, with total irradiation induced change typically two orders of magnitude greater and DOC normalised CO2 production a factor of two higher in the headwater stream samples. This is attributed to longer water residence times in the reservoir rendering a higher proportion of the DOC recalcitrant to photo-processing. Overall the magnitude of photo-induced C losses was significantly positively correlated with DOC concentration in the headwater stream, which varied seasonally with highest concentrations detected in late autumn and winter. Rainfall events were identified as important in replenishing the stream system with photoreactive material, with lignin phenol data indicating mobilisation of fresh DOC from woody vegetation in the upper catchment during a winter rainfall event. Whilst these data clearly demonstrate that peatland catchments generate significant volumes of photoreactive DOC, the degree to which it is processed in the aquatic environment is unclear. Field investigations were undertaken to address this uncertainty. In-situ experiments with unfiltered water samples in light and dark conditions were conducted in two contrasting open water peatland pool systems. At the high DOC site (Red Moss of Balerno, SE Scotland), DOC concentrations in surface light exposed samples decreased by 18% compared to dark controls over 9 days and light treatments were enriched in CO2 and CH4. Photochemical processing was evident in δ13C-DOC and δ13C-DIC signatures of light exposed samples, which were enriched and depleted, respectively, relative to dark controls (+0.23 ‰ and -0.38 ‰) after 9 days of surface exposure. At the low DOC site (Cross Lochs, Forsinard, N Scotland) net production of DOC occurred in both light and dark samples over the experiment duration, in part due to POC breakdown. δ13C-DIC signatures indicated photolysis had occurred in light exposed samples (-1.98 ‰), whilst δ13C-DOC data suggest an absence of photo-processing, as the signatures in both treatments were similar. Accounting for light attenuation through the water column, 46 ± 4.9 and 8.7 ± 0.5 g C-CO2 eq m−2 yr−1 was processed by photochemical and microbial activity in peatland pools within the catchments at the high and low DOC sites, respectively. At both sites, light driven processing was responsible for a considerable percentage (34 and 51%) of gaseous C production when compared to equivalent estimates of microbial C processing and thus should be considered a key driver of peatland pool biogeochemical cycles. It is clear from this study that temperature, seasonal cycles, rainfall events and water residence time provide strong controls on the photoreactivity of aquatic C in Scottish peatland systems. The photo-processing pathway has the potential to alter the C balance of peatland catchments with a high percentage coverage of aquatic systems. Under climate change scenarios where light, temperature and rainfall conditions are expected to change, this process may become increasingly important in aquatic C cycling, particularly if the upward trend in DOC concentrations in northern aquatic systems continues.

Orientador: Fabio Luiz Camargo Villela Berbert
Resumo: O melhor tratamento para dentes permanentes avulsionados é o reimplante imediato, porém, quando o dente permanece fora do alvéolo por longo período, o prognóstico pode ser prejudicado. Condutas têm sido buscadas na tentativa de melhorar os problemas decorrentes de reimplantes tardios. A laserterapia, devido à sua propriedade anti-inflamatória, e o plasma rico em plaquetas (PRP), devido à liberação de fatores de crescimento, são boas alternativas visando atenuar o processo inflamatório e auxiliar o processo de reparo. Avaliou-se os efeitos da laserterapia, da aplicação do PRP e da associação de ambos sobre o reimplante tardio de incisivos superiores de ratos. Cinquenta animais foram divididos em dez grupos experimentais (n=5): grupo controle onde o incisivo superior direito não recebeu alguma intervenção, e nove grupos onde houve a extração dentária simulando uma avulsão seguida do reimplante após 40 minutos. Em um desses grupos, a polpa foi mantida no canal radicular, e os demais foram submetidos à um protocolo de tratamento, de acordo com a condição da cavidade pulpar (manutenção da polpa, preenchimento com hidróxido de cálcio ou preenchimento com PRP) e tratamento do alvéolo/periodonto (coágulo ou PRP com ou sem laserterapia). As avaliações foram realizadas por meio de análise histológica e histoquímica após 30 dias e por microtomografia computadorizada (micro-CT) sobrepondo-se as imagens dos períodos imediato e 30 dias após o reimplante. Os dados obtidos a ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The best treatment for avulsed permanent teeth is immediate replantation, but when the tooth remains outside the alveolus for a long period, the prognosis may be impaired. Pipelines have been sought in an attempt to improve the problems arising from late reimplants. Laser therapy, due to its anti-inflammatory property, and platelet-rich plasma (PRP), due to the release of growth factors, are good alternatives aimed at attenuating the inflammatory process and assisting the repair process. The effects of laser therapy, the application of PRP and the association of both on the delayed replantation of upper incisors of rats were evaluated. Fifty animals were divided into ten experimental groups (n = 5): control group where the right upper incisor did not receive any intervention, and nine groups where the dental extraction was performed simulating an avulsion followed by reimplantation after 40 minutes. In one of these groups, the pulp was maintained in the root canal, and the others were submitted to a treatment protocol, according to the condition of the pulp cavity (pulp maintenance, calcium hydroxide filling or filling with PRP) and treatment of the pulp. Alveolus / periodontium (clot or PRP with or without laser therapy).The evaluations were performed through histological and histochemical analysis after 30 days and by computerized microtomography (micro-CT) overlapping the images of the periods immediately and 30 days after the replantation. The data obtained from the histological and histochemical evaluations were analyzed by the ANOVA and Tukey tests and the microtomographic data by the Kruskall Wallis and Dunn tests, with a significance level of 5%. After histological and histochemical analysis, it was verified that there was no statistically significant difference between groups regarding the number of clasts/mm ...(Complete abstract electronic access below)
Doutor

Os baixos índices produtivos da pecuária de corte no Brasil são normalmente associados à baixa produtividade e ao baixo valor nutritivo das espécies de gramíneas forrageiras tropicais nas condições edafo-climáticas onde se desenvolve a atividade no país. O presente trabalho procurou elucidar se a freqüência de desfolhação baseada em tempo cronológico constante iria gerar, além de dosséis com condição estrutural e fisiológica diferente a cada pastejo, forragem em oferta com características qualitativas também diferentes em cada evento de pastejo tentando-se estabelecer a importância relativa da idade fisiológica em comparação com a idade cronológica na determinação dos indicadores (químico-bromatológicos e físicos) do valor nutritivo da forragem em oferta. O experimento foi conduzido em Piracicaba, na ESALQ/USP, no Departamento de Zootecnia de setembro de 2005 a fevereiro de 2006. O delineamento foi inteiramente casualizado, com três tratamentos correspondendo às estratégias de pastejo, sendo duas definidas em função da interceptação luminosa (IL) pelo dossel durante a rebrotação (pastejos iniciados com 95% ou 100% de IL) e um baseado no tempo cronológico (pastejos iniciados a cada 28 dias), e três repetições. Piquetes manejados com 95% IL produziram forragem composta basicamente por folhas (92,5%). Esse mesmo tratamento produziu forragem com alto teor de proteína bruta (PB; 141 g kg-1 nas folhas, 89 g kg-1 nos colmos e 138 g kg-1 na forragem íntegra), concentrações menores de fibra em detergente neutro (FDN) de colmos (740 g kg-1), e maiores valores de digestibilidade in vitro da matéria seca de folhas (690 g kg-1) e de colmos (660 g kg- 1), resultando portanto em forragem com melhor valor nutritivo. Os tratamentos com menor freqüência de pastejo (100% IL e 28 dias) resultaram em forragem com maior proporção de colmos (9,8 e 9,1 % respectivamente). Teores de PB foram inferiores na forragem pastejada a cada 28 dias (71 g kg-1 para colmos e 114 g kg-1 para forragem íntegra) e as maiores concentrações de FDN de colmos foram obtidas na forragem colhida com 100% IL (769 g kg-1) e com 28 dias (764 g kg-1). A resistência ao cisalhamento de colmos foi menor na forragem produzida a 95% IL (9 kgf), enquanto que os maiores índices foram encontrados para os tratamentos 100% IL (10,5 kgf) e 28 dias (11,2 kgf). A uniformização fisiológica dos tratamentos baseados em IL não resultou em conseqüente uniformização dos determinantes qualitativos da forragem em oferta, pois tanto o tratamento 95% IL quanto o 100% IL resultaram em forragem com diferenças entre os ciclos de pastejo, principalmente com relação à forragem íntegra. O tratamento baseado em dias fixos, como esperado, também não foi considerado uniforme neste mesmo sentido.
The low productive indices of the beef cattle industry in Brazil are normally associated with the low productivity and the low nutritive value of the tropical forage species in the climatic conditions where the activity is developed in the country. The objective of this study was to ascertain whether the defoliation frequency based on constant chronological time would generate, besides different sward structural and physiological conditions at each grazing, forage on offer with different qualitative characteristics, and try to establish the relative importance of the physiological age in comparison with the chronological age in the determination of the indicators (chemical and physical) of forage nutritive value. The experiment was carried out in Piracicaba, at ESALQ/USP - Departamento de Zootecnia from September 2005 through February 2006. The experimental design was completely randomized, with three treatments corresponding to the grazing strategies, which was two defined by light interception (LI) (grazing started with 95% LI or 100% LI) and one based on chronological time (grazing started every 28 days), each replicated three times. Forage produced on paddocks managed with 95% LI were mostly leaves (92,5%). That same treatment produced forage with high concentration of crude protein (CP; 141 g kg-1 in leaves, 89 g kg-1 in stems and 138 g kg-1 in whole forage), low concentrations of neutral detergent fiber (NDF) in stems (740 g kg-1), and higher values of in vitro dry matter digestibility (IVDMD) of leaves (690 g kg-1) and stems (660 g kg-1), resulting in forage with higher nutritive value. Low grazing frequency treatments (100% LI and 28 days) resulted in forage with higher proportion of stems (9,8 and 9,1 %, respectively). Concentrations of CP were lower in forage grazed every 28 days (71 g kg-1 in stems and 114 g kg-1 in whole forage) and the higher concentrations of NDF in stems were obtained from forage harvested with 100% LI (769 g kg-1) and with 28 days (764 g kg1). The shear strength of stems was lower in forage produced with 95% LI (9 kgf), whereas that with the higher indices was founded for the treatments 100% (10,5 kgf) and 28 days (11,2 kgf). The physiological uniformization of treatments based in LI did not resulted in consequent uniformization of qualitative determinants of the offered forage, because both treatments 95% LI and 100% LI resulted in forage with differences among grazing cycles, mainly in relation to whole forage. The treatment based on fixed days of rest, as expected, did not resulted in uniformity as well.

A combinação entre freqüência e intensidade de pastejo determina amplitudes de manejo que podem propiciar produção de forragem em quantidade e qualidade, além de elevada eficiência de colheita. Nesse contexto, o presente experimento teve o objetivo de estudar aspectos relacionados à produção, composição morfológica e valor nutritivo da forragem em pastos de capim-marandu submetidos a estratégias de pastejo rotativo por bovinos de corte. O experimento foi conduzido em área do Departamento de Zootecnia da USP/ESALQ, em Piracicaba, SP, durante o período de outubro de 2004 a setembro de 2005. Os tratamentos corresponderam à combinação entre duas intensidades, alturas pós-pastejo de 10 e 15 cm, e dois intervalos entre pastejos, representados pelo período de tempo necessário para que 95 e 100% de luz incidente fosse interceptada pelo dossel, e foram alocados às unidades experimentais (piquetes de 1.200 m2) segundo um delineamento de blocos completos casualizados e arranjo fatorial 2 x 2, com 4 repetições. Foram avaliadas as seguintes variáveis: interceptação de luz, altura do dossel, massa de forragem, acúmulo total de forragem e de folhas, taxa de acúmulo de forragem e de folhas, composição química e morfológica da forragem produzida. De forma geral, os pastos acumularam forragem de forma semelhante durante o período experimental, porém, pastos manejados com 95% de IL apresentaram maior proporção de folhas (51,8 e 41,9%) e menor proporção de colmos (39,1 e 41,5%) e material morto (9,1 e 16,6%) que pastos manejados com 100% de IL na massa de forragem pré-pastejo, especialmente na primavera 1 (out-dez/04). Isso resultou em maior digestibilidade da forragem nos pastos de 95% em relação àqueles de 100% de IL (66,7 e 57,9%, respectivamente). No geral, as metas de altura pós-pastejo dos pastos manejados com 95% de IL foram mantidas relativamente constantes durante todo o período experimental. Contrariamente, as metas de altura pós-pastejo para os pastos submetidos ao tratamento 100/10 aumentaram ao longo do experimento, atingindo um valor 56% superior à meta original ao final das avaliações. As metas de 95% e 100% de IL estiveram consistentemente associadas a valores de altura pré-pastejo dos pastos relativamente estáveis de 25 e 35 cm, respectivamente. Pastos manejados com 95% de IL apresentaram maior proporção de folhas no resíduo em relação àqueles manejados com 100% de IL (15,5 e 8,9% respectivamente), o que propiciou que esses interceptassem mais luz após o pastejo, garantindo rebrotações mais rápidas, intervalos entre pastejos mais curtos e maior número de ciclos de pastejo. Com base nos padrões de IL e variações em composição morfológica e valor nutritivo da forragem produzida, a estratégia de pastejo mais adequada para o capim-marandu seria aquela com pastejos realizados quando 95% da IL seja atingida (25 cm de altura) durante a rebrotação e rebaixados até uma altura pós-pastejo de 15 cm.
Combinations between frequency and intensity of grazing determine a range of management possibilities that can ensure the high production of quality herbage and, additionally, high efficiency of grazing. Against that background, the objective of this experiment was study aspects related to the accumulation, morphological composition and nutritive value of the herbage in marandu palisadegrass swards subjected to rotational stocking strategies by beef cattle. The experiment was carried out at Departamento de Zootecnia, USP/ESALQ, Piracicaba, SP, from October 2004 to September 2005. Treatments corresponded to combinations between two grazing intensities, post-grazing residues of 10 and 15 cm, and two grazing frequencies, equivalent to the period of time necessary for swards to reach 95 and 100% interception of the incident light during regrowth – LI, and were allocated to experimental units (1200 m2 paddocks) according to a complete randomised block design and a 2 x 2 factorial arrangement, with 4 replications. The following response variables were analysed: sward light interception, height, herbage mass, total dry matter and leaf accumulation, morphological and chemical composition of the accumulated herbage. In general, all swards accumulated similar amounts of herbage at the end of the experimental period, however, swards grazed at 95% LI showed higher proportion of leaf (51.8 and 41.9%) and lower proportion of stem (39.1 and 41.5%) and dead material (9.1 and 16.6%) in the herbage mass pre-grazing than swards grazed at 100% LI, particularly during spring 1 (Oct-Dec/04). This resulted in higher digestibility of the herbage on swards grazed at 95% than at 100% LI (66.7 and 57.9%, respectively). Targets of post-grazing heights were maintained relatively constant throughout the experimental period on the swards grazed at 95% LI. On the other hand, the target of post-grazing height for the 100/10 could not be maintained, and increased as the experiment progressed, reaching a final value 56% higher than originally planned. The pre-grazing targets of 95 and 100% LI were consistently associated with relatively stable values of sward height around 25 and 35 cm, respectively. Swards grazed at 95% LI showed higher proportion of leaf in the post-grazing herbage mass than those grazed at 100% LI (15.5 and 8.9%, respectively), favouring a higher light interception soon after grazing and ensuring faster regrowth, shorter grazing intervals and higher number of grazing cycles. Based on the patterns of LI and variations in morphological composition and nutritive value of the accumulated herbage, the most appropriate grazing strategy for the marandu palisadegrass correspond to grazings carried out when 95% interception of the incident light is reached during rebrowth (25 cm of sward height) to a post-grazing residue of 15 cm.

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The pastures are formed by a population of plants and each plant is formed by basic units called tillers. Management practices allow the knowledge of the processes of tillering. The nutritional value of pasture is determined by chemical composition of the plant and its digestibility may be affected by nutrient supply, the station year and the grazing management. An experiment was conducted at Embrapa Rice and Beans-Midwest Center for Dairy Research, in order to evaluate the tillering and nutritive value of grasses and Marandu Xaraés fertilized with nitrogen (N) and potassium (K) (0, 100, 200 and 300 kg / ha / year), from December 2007 to May 2008. The experiment was complete block design with three replications. Data Tiller were grouped in four seasons during the trial period for the variable tiller density (DPP) and three times for other variables (TAP, TSP, and TMP IEP). The evaluation of tillering was held in an area demarcated by tillers known. From the initial population, each grazing were identified new populations of tillers, marked with different colored wires. For the value data nutrition were evaluated in the dry season and water. The collection of samples was performed by simulated grazing were analyzed and the CP, NDF, ADF, lignin and IVDMD. In the review of DPP, there were dose effect (P = 0.0510) and age (P <0.0001), and after the grazing periods, the DPP is stabilized. No differences were found between seasons for the rate of tillers (TAP) to treat 300 kg of N and K / ha / year. In rainy season, the mortality rate of tillers (TMP) were lower the dose of 300 kg N and K / ha / year. The survival rate of tillers (TSP) was higher in water at a dose of 300 kg N and K / ha / year and 200 kg of N and K / ha / year, not different from the other doses. The stability index of tillers (IEP) remained above 1.0 in all treatments and times. For capimxaraés, the linear increase in fertilizer levels stimulated tillering with the increase in DPP to 300 kg of N and K / ha / year. Waters, the dose of 100 kg of N and K / ha / year showed higher TAP. The other doses and times not differed. In the waters between 0 and 100 kg of N and K / ha / year yielded the highest TMP. However, the dose of 100 kg of N and K / ha / year did not vary from 200 kg N and K / ha / year, with intermediate values. At a dose of 300 kg of N and K / ha / year were observed the lowest TMP. It was observed that the pastures fertilized 300 kg of N and K / ha / year had the highest TSP in relation to too, for the waters. The highest values were found in the TSP dry seasons. The stability index of tillers (IEP) remained above 1.0 in all treatments and times. At a dose of 300 kg of N and K / ha / year was observed the highest TSP during the rainy season, although the highest values have been in the dry season. The NDF, ADF and lignin were not influenced by fertilization, but the ADF (33.40 and 31.20% respectively) and lignin (3.93% and 2.97, respectively) were higher in the rainy season. The average CP of pastures were not affected by fertilization, except for CP content pastures fertilized with 200 kg N and K / ha / year was higher (P = 0.0353) during the rainy season. The concentration of NDF pastures fertilized with N were 7.7 and 7.1% lower (P = 0.0368) than Unfertilized, in times of rainy and dry seasons, respectively. The levels Average ADF were not affected by fertilization, but the average content FDA pastures in the rainy season was lower (P = 0.0933) than during the drought. The average content of lignin pastures fertilized with 200 kg of N and K / ha / year was higher (P = 0.0547) than in pastures fertilized with 100 N and K / ha / year (2.27 and 3.86% respectively). The average IVDMD of pasture was higher Unfertilized (P = 0.0476) than that of pastures fertilized with 200 kg of N and K / ha / year, and in rainy season, the IVDMD of pasture was not fertilized greater than that of fertilized pastures. In the pastures fertilized with 300 kg of N and K / ha / year, IVDMD in the rainy season was higher (P = 0.0155) than in the dry season. Pastures xaraés unfertilized grass are prone to susceptibility degradation in the short term and it is recommended fertilization rates above 200 kg N and K / ha / year. Grazing management based on light interception proved valid for pastures that receive manure. Pastures are fertilized more stable compared to the dynamics of tillering. There was no variation IVDMD significantly due to fertilization rates and periods studied with always harvested forage in the same physiological maturity. When the pasture was managed based on IL fertilization affected only the CP. Fertilization did not affect the nutritional value of grass xaraés subjected to grazing management IL-based.
As pastagens são formadas por uma população de plantas e cada planta é formada por unidades básicas denominadas de perfilhos. As práticas de manejo permitem o conhecimento dos processos de perfilhamento. O valor nutritivo das pastagens é determinado pela composição bromatológica da planta e pela sua digestibilidade, podendo ser afetado pelo suprimento de nutrientes, pela estação do ano e pelo manejo do pastejo. Foi conduzido um experimento na Embrapa Arroz e Feijão-Núcleo Centro-Oeste de Gado de Leite, com o objetivo de avaliar o perfilhamento e o valor nutritivo dos capins Marandu e Xaraés adubados com doses de nitrogênio (N) e de potássio (K) (0, 100, 200 e 300 kg/ha/ano), no período de dezembro de 2007 a maio de 2008. O delineamento experimental foi o de blocos completos ao acaso com três repetições. Os dados de perfilhamento foram agrupados em quatro épocas durante o período experimental para a variável densidade populacional de perfilhos (DPP) e em três épocas para as demais variáveis (TAP, TSP,TMP E IEP). A avaliação do perfilhamento foi realizada em perfilhos demarcados por uma área conhecida. A partir da população inicial, a cada pastejo foram identificadas novas populações de perfilhos, marcadas com arames de diferentes cores. Para os dados de valor nutritivo foram avaliadas na época da seca e das águas. A coleta de amostras foi realizada por meio de pastejo simulado e foram analisado os teores de PB, FDN, FDA, lignina e a DIVMS. Nas avaliações de DPP, houve efeito de dose (P=0,0510) e de época (P<0,0001) e, após os ciclos de pastejos, a DPP se estabilizou. Não foram verificadas diferenças entre as épocas do ano para a taxa de aparecimento de perfilhos (TAP) no tratamento de 300 kg de N e K/ha/ano. Na época das águas, as taxas de mortalidade de perfilhos (TMP) foram menores para a dose de 300 Kg N e K/ha/ano. A taxa de sobrevivência de perfilhos (TSP) foi maior nas águas na dose de 300 Kg de N e K/ha/ano e a dose de 200 kg de N e K/ha/ano, não diferiu das demais doses. O índice de estabilidade de perfilhos (IEP) manteve-se superior a 1,0 em todos os tratamentos e épocas. Para o capimxaraés, o aumento linear nas doses de adubação estimulou o perfilhamento com o aumento na DPP para a dose de 300 kg de N e K/ha/ano. Nas águas, a dose de 100 kg de N e K/ha/ano apresentou maior TAP. As demais doses e épocas não diferiram. Nas águas as doses 0 e 100 kg de N e K/ha/ano, apresentaram a maior TMP. Porém, a dose de 100 kg de N e K/ha/ano não diferiu de 200 kg de N e K/ha/ano, com valores intermediários. Na dose de 300 kg de N e K/ha/ano, foram observados os menores valores TMP. Foi observado que os pastos adubados com 300 kg de N e K/ha/ano apresentaram as maiores TSP em relação aos demais, durante as águas. Os maiores valores de TSP foram encontrados nas épocas secas. O índice de estabilidade de perfilhos (IEP) manteve-se superior a 1,0 em todos os tratamentos e épocas. Na dose de 300 kg de N e K/ha/ano, foi observado a maior TSP no período das águas, embora os maiores valores tenham sido na época seca. Os teores de FDN, de FDA e de lignina não foram influenciados pela adubação, porém teores de FDA (33,40 e 31,20% respectivamente) e lignina (3,93 e 2,97%, respectivamente) foram maiores na época das águas. Os teores médios de PB dos pastos não foram afetados pela adubação, exceção ao o teor de PB dos pastos adubados com 200 kg de N e K/ha/ano foi maior (P = 0,0353) no período das águas. Os teores médios de FDN dos pastos adubados com N foram 7,7 e 7,1% menores (P= 0,0368) do que os não adubados, nas épocas das águas e da seca, respectivamente. Os teores médios de FDA não foram influenciados pela adubação, porém o teor médio de FDA dos pastos na época das águas foi menor (P=0,0933) do que no período da seca. O teor médio de lignina dos pastos adubados com 200 kg de N e K/ha/ano foi maior (P=0,0547) do que nos pastos adubados com 100 de N e K/ha/ano (2,27 e 3,86%, respectivamente). A DIVMS média dos pastos não adubados foi maior (P=0,0476) do que a dos pastos adubados com 200 kg de N e K/ha/ano e, na época das águas, a DIVMS dos pastos não adubados foi maior do que a dos pastos adubados. Nos pastos adubados com 300 kg de N e K/ha/ano, a DIVMS na época das águas foi maior (P=0,0155) do que na época da seca. Pastos de capim-xaraés sem adubação apresentam tendência a susceptibilidade a degradação em curto prazo e recomenda-se doses de adubação acima de 200 kg de N e K/ha/ano. O manejo do pastejo baseado em interceptação luminosa mostrou-se válido para pastos que recebem adubação. Pastos adubados são mais estáveis em relação a dinâmica do perfilhamento. Não houve variação significativa da DIVMS devido às doses de adubação e épocas estudadas com a forragem colhida sempre na mesma maturidade fisiológica. Quando a pastagem foi manejada baseada na IL a adubação afetou apenas o teor de PB. A adubação não afetou o valor nutritivo de capim-xaraés submetido ao manejo do pastejo baseado em IL.

"Rice (Oryza sativa L.) is the staple food for more than half of the world population, and it is very sensitive to adverse environmental conditions. It is also very important for Portugal, which is the biggest rice consumer in Europe with a consumption of 14.8 kg/capita/year. Nowadays, due to climate changes and competition with other crops, the arable land for rice is decreasing. To overcome this and feed the growing world population, keeping the prices affordable, it is estimated that rice yield needs to grow 1.0–1.2% annually beyond 2020. Therefore, it is urgent to develop rice with higher grain yield and more resistant to adverse environmental conditions.(...)"
N/A

CARVALHO, Fabrício Eulálio Leite. Chloroplast redox metabolism and npq regulation in arabidopsis and rice exposed to excessive light: new insights into psii photoprotection mechanisms. 2016. 171 f. Tese (Doutorado em Bioquímica)-Universidade Federal do Ceará, Fortaleza, 2016.
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Plants are sessile organisms, which evolved from aquatic environment to land. This crucial change in habitat opened a new word of resources, but also generated numerous adaptive challenges. Among these defies, sustain photosynthesis under an excessive light environment consist in one of the most important adverse factors to be overcame by plants. Excessive light is defined as the light absorbed by plants, which exceeds their photosynthetic capacity. Under such conditions, the over-accumulation of oxygen reactive species (ROS) could lead to impairment on photosystem two reaction centers (RCII), generating photoinhibition and affecting negatively crop productivity. In this sense, the development of photoprotective mechanisms was essential for plants surviving. Among such mechanisms, non-photochemical quenching (NPQ) and antioxidative metabolism have been intensively studied. However, the real importance of such photoprotective mechanisms and the possible integrative processes which connect NPQ and redox metabolism still not totally understood. The present study addressed to comprehend the integrative mechanisms underlying NPQ and antioxidative processes in two different plants species: one classic plant model (Arabidopsis thaliana) and one important crop model (Oryza sativa). In order to reach such objectives, first was employed new fluorimetric-based methodologies related to photoinhibition quantification, involving photochemical quenching measured in the dark subsequently illumination (qPd) and the fraction of NPQ formed which was related to photoprotection (pNPQ). The use of this methodology was well succeed with A.Thaliana plants under an important physiological problem: light tolerance during plant ontogenesis. The importance of ROS accumulation during less tolerant developmental phases (juvenile and senescent) and chlorophyll concentrations were discussed. Subsequently, the mechanisms underlying pNPQ formation were investigated in the same model, which revealed the importance of combined adjustments in PsbS protein expression, delta pH formation and zeaxanthin/violaxanthin pigment contents for phototolerance during A. thaliana ontogenesis. The importance of total xanthophyll pool in pNPQ generation was evaluated. Finally, the current study attempted to employ the methodology involving qPd in a crop model (rice) knockdown for thylakoidal ascorbate peroxidase isoform (APX8 proteins; apx8 = transformed plants). The data revealed new importance for APX8, which were more sensitive to light, specially under moderate growth light (400 µmol m-2 s-1) compared with non-transformed (NT). Transformed apx8 plants accumulated less chlorophyll, over-accumulated H2O2 and presented impairment on thermal component of NPQ (qE) formation. Under high light intensities growth conditions (4 days), apx8 plants activated compensatory mechanisms which were probably effective as photoprotective mechanism.
Plantas são organismos sésseis e por sua natureza precisaram desenvolver diversos mecanismos ligados a maximização da utilização dos recursos primordiais disponíveis para sua sobrevivência nas mais diversas condições ambientais. Em condições ambientais ótimas de crescimento, a intensidade de energia absorvida a partir da luz incidente equivale a demanda energética exercida pela atividade metabólica circunstancial da planta. Entretanto, na quase totalidade dos casos, tais condições não existem na natureza. O excesso de luz é caracterizado por uma condição ambiental na qual o organismo vegetal é submetido a uma quantidade de energia luminosa mais alta do que a capacidade de utilização nas reações bioquímicas que compõem o metabolismo celular necessário para o crescimento normal do indivíduo. Sendo assim, o excesso de luz pode ser consequência de altas intensidades de luz incidente ou devido a restrições nas reações de consumo de poder redutor, especialmente assimilação de CO2. Portanto, plantas submetidas a estresse salino por exemplo, o qual está muitas vezes associado a uma restrição de natureza estomática, podem apresentar estresse de excesso de luz, mesmo sob intensidades moderadas de luz incidente. A energia excedente pode aumentar a probabilidade da ocorrência de reações colaterais tais como a formação das espécies reativas de oxigênio (EROS). Essas moléculas de alta reatividade podem gerar diversos efeitos negativos para o funcionamento celular, incluindo desnaturação de proteínas, peroxidarão lipídica de membranas e fotoinibição da atividade do fotossistema II (PSII). A ocorrência de fotoinibição é extremamente negativa para o crescimento e desenvolvimento vegetal, afetando a produção de alimentos global. Entretanto, pressões evolutivas causadas pela seleção natural conduziram ao aparecimento de diversos mecanismos de proteção fotooxidativa. Entre as respostas de fotoproteção acionadas em vegetais, duas merecem especial destaque: a dissipação de energia na forma de calor (componente qE do quenching não-fotoquímico - NPQ) e a modulação da expressão de genes ligados a rotas de síntese de antioxidantes enzimáticos e não enzimáticos. Em uma perspectiva sistêmica, entretanto, nenhuma dessas respostas ocorre de maneira isolada em uma célula vegetal. Contrariamente, esses mecanismos interagem de maneira contínua e interdependente, partilhando substratos e rotas de sinalização, e, deste modo, conduzindo à aclimatação da planta às condições de excesso de luz. O presente estudo de doutorado objetivou primariamente aprofundar os conhecimentos existentes acerca dos papéis do NPQ na fotoproteção de plantas. Com esse intuito, plantas modelo da espécie Arabidopsis thaliana foram utilizadas para entender as dinâmicas fotossintéticas em resposta ao excesso de luz. Uma metodologia pioneira para a detecção de fotoinibição, baseada em técnicas de fluorimetria da clorofila a relacionadas à quantificação do quenching fotoquímico medido no escuro, subsequente a um período de iluminação (qPd) foi utilizada. Essa metodologia permite a quantificação dos primeiros indícios de fechamento permanente dos centros de reação do PSII (RCII) e possibilita a quantificação da fração de NPQ que de fato contribui para a fotoproteção (pNPQ). Plantas de Arabidopsis de diferentes idades foram utilizadas, objetivando-se a aplicação da metodologia em um problema fisiológico relevante. Os resultados obtidos nesse estudo são apresentados no capítulo 2 do pressente trabalho e evidenciam que: a) plantas de Arabidopsis apresentam maior susceptibilidade a fotoinibição nas fases juvenil e senescente da ontogênese, b) a fotoproteção foi positivamente associada com a maior eficiência de formação do pNPQ e conteúdo total de clorofilas; c) a maior susceptibilidade a fotoinibição foi coincidiu com acúmulo de EROS nas fases juvenil e senescente e d) o uso da técnica baseada no qPd foi bem sucedido, evidenciando o potencial para futuras aplicações em outros contextos fisiológicos. Posteriormente, buscou-se um maior entendimento acerca dos mecanismos inerentes ao parâmetro pNPQ. Utilizou-se uma abordagem simplificada consistindo em apenas três fases ontogenéticas de plantas de Arabidopsis no intuito de investigar os processos de conhecido envolvimento com a formação do qE, ΔpH, relação violoxantina/zeaxantina e quantidade da proteína PsbS. Esses dados estão relacionados no capítulo 3 do presente trabalho e evidenciam que: a) plantas senescentes e juvenis apresentam menor quantidade de PsbS e formação de ΔpH respectivamente em comparação a plantas maduras, b) as plantas maduras apresentam maior quantidade de pigmentos xantofilas, o que em combinação com maiores níveis de clorofila reportados anteriormente podem explicar uma maior eficiência e potencial na formação de qE, o qual estaria intimamente ligado ao pNPQ. Finalmente, o presente trabalho de doutorado buscou a aplicação dos conhecimentos gerados acerca das novas técnicas de detecção da fotoinibição e pNPQ em uma planta modelo de interesse agronômico, arroz (Oryza sativa). Objetivando-se investigar a relação das EROS com os processos de fotoproteção associados ao pNPQ, plantas de arroz silenciadas por meio de RNAi para a expressão das APX de tilacóides (APX8) foram empregadas. Os resultados obtidos nesses estudos se encontram no capítulo 4 da presente tese e evidenciam que: a) em luz moderada, plantas silenciadas (apx8) apresentam maior susceptibilidade a fotoinibição associada a menor acúmulo de biomassa e menor produtividade, b) essas características das plantas apx8 provavelmente estiveram ligadas a menor eficiência de formação de pNPQ e qE, c) as diferenças relacionadas ao pNPQ provavelmente estiveram associadas com menor conteúdo de clorofilas e acúmulo de EROS nas plantas apx8, evidenciando novamente a importância desses fatores com a capacidade de fotoproteção em plantas e d) em condições de aclimatação ao excesso de luz, a ausência da APX8 é compensada por outras peroxidases, levando a redução nos níveis de EROS e provavelmente recuperação dos níveis de clorofila, que levam a uma recuperação do fenótipo evidenciado em luz moderada.Conclui-se com a presente tese que o uso das metodologias relacionadas a determinação do qPd para estudos de integridade dos RCII foi eficaz para duas espécies distintas, Arabidopsis thaliana e Oryza sativa. Adicionalmente, os resultados indicam que a eficiência de formação do pNPQ parece ser um fator determinante para a capacidade de fotoproteção, que por sua vez é dependente do conteúdo de pigmentos fotossintéticos, especialmente clorofila e carotenoides, assim como eficiência do metabolismo antioxidativo. Essas relações são primeiramente descritas no presente trabalho de doutorado e apresentam potencial de aplicação futura em estudos envolvendo obtenção de plantas mais tolerantes ao excesso de luz. Tais condições de excesso de luz são recorrentes em diversas regiões do mundo, mas especialmente importantes em regiões do semiárido do nordeste do Brasil, onde se encontram em combinação com outros fatores de estresse abiótico, tais como seca e alta salinidade do solo. Espera-se com essas descobertas, contribuir para o conhecimento científico da área de bioquímica vegetal e, posteriormente, possibilitar sua aplicação em âmbito do desenvolvimento agrícola regional.

Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 1997.
Includes bibliographical references.
Issues: Regional architecture vs. globalization.
by Alberto J. Cabré.
M.Arch.

Master of Agribusiness
Department of Agricultural Economics
Vincent Amanor-Boadu
This research identifies factors that distinguish rural women who have migrated to Bangkok for the purpose of enhancing their economic wellbeing by engaging in the sex industry and those who have stayed in their rural communities and are not engaged in the sex industry. The research used primary data collected through interviews in the red light districts of Bangkok and Pattaya and in villages in the rural provinces of Buriram, Udon Thani, Sakon Nakhon, Chayaphum and Khon Kaen in Thailand. A total of 100 respondents provided information for the study: 55 percent from the red light districts and the remainder from the provinces. The data were analyzed using logit regression modeling approach as well as statistical analysis. The statistical analysis provided the descriptive statistics of the respondents and an overview of the data. The logit regression modeling approach facilitated the estimation of the responses of the probability of working in the red light entertainment districts to specified demographic and psychographic variables. The pseudo R-square of the logit model was 46.2 percent for the base model, which included age, marital status, number of male and female siblings respectively, birth position and number of children, education, financial responsibility and average monthly age. The results indicated that marital status was significant at the 1 percent level, exhibiting a marginal effect of about -35.2 percent. That is, when the marital status of a respondent changed from unmarried (0) to married (1), the probability of sex industry participation decreased by about 35 percent. Assessing the effect only among respondents with children, the results are not very different from the base model. The pseudo R-square for this model – which is the same as the base model, except that it has Teen Mother as a variable – was 61.4 percent with a total number of observations of 78 instead of the original 100. This implies that about 22 respondents did not have any children. In this model, the marital status variable is significant at the 1 percent level as was the number of female siblings. The average monthly wage is significant at the 5 percent level, with a 1000 Thai Baht increase in wages leading to a marginal 0.01 percent decline in the probability of sex industry participation. Education, under this model, is statistically significant at the 10 percent level, with another year of education decreasing the probability of sex industry participation by 2.5 percent. The foregoing provides some clear policy direction. Specific efforts may be invested in enhancing the education of women in Thailand, which is expected to increase their economic situation. However, this expectation would not materialize if investments are not made to enhance the economic opportunities available to women across the economic spectrum. Perhaps most importantly, however, this study shows that incremental improvement in educational and economic opportunities for rural women alone may not achieve lasting results if cultural paradigms regarding marriage, relational fidelity and imbalanced socio-cultural obligations of daughters are not addressed in tandem.

碩士
國立成功大學
電機工程學系
104
In this study, silicon-rich oxide/silicon dioxide multilayers (SRO/SiO2 MLs) were synthesized by reactive magnetron sputtering in a gas mixture of argon and oxygen. In particularly, the variation from 0 to1.0 sccm in the oxygen flow was used. The structural, optical, and electrical properties of the SRO/SiO2 MLs were investigated by TEM, PL, XPS and EL measurements, where the excitation laser was employed by the 325, 532 and 633 nm for the PL analysis. The PL emission was originated from the band-to-band transition within the Si-NCs and the radiative recombination centers at the Si-NCs/SiO2 interface. The results demonstrate that size of Si-NCs was decreased due to quantum-size effect as increasing the oxygen flow. The enhancement of EL in the visible range was achieved by using oxygen flow of 0.15 sccm. Relationship between PL and EL in the SRO/SiO2 MLs has been examined. The blueshift in the EL was attributed to the band filling effect under high current injection mode. The EL spectra at different oxygen flows were recorded, and the correlation between charge transport mechanisms and EL properties was discussed.

博士
國立交通大學
光電工程系所
95
This dissertation explores the fabrication, structural properties, physical features, optical and electronic properties of Si-rich SiO2 (SiOx) material and light emitting device with buried nanocrystallite silicon. The main focus of this dissertation can be divided into five parts. First, the white-light and blue-green electroluminescence (EL) from an Ag/ Si-ion-implanted SiO2 (SiO2:Si+)/n-Si/Ag metal-oxide-semiconductor light emitting diode (MOSLED) with the defect-enhanced blue-green photoluminescence (PL) are studied. After annealing for 180 min at 1100oC, the main irradiative defects corresponding to PL at 415, 455 and 520 nm are completely activated, which are identified as weak oxygen bond (WOB), the neutral oxygen vacancy (NOV)-related defects and E'delta-related defects, respectively. During the Si implantation (or physical bombardment with high-energy ions), the oxygen vacancies and the oxygen interstitials (the precursors for the WOB defects) are created due to the relatively large quantities of oxygen that are displaced from their atomic positions in the SiO2 matrix. The EL spectrum of the MOS diode under different reverse bias conditions indicates that the irradiative recombination is due to enhanced impact ionization of ground states of defects, such as WOB, NOV, and E'delta defects, through the injection of holes accumulated in the inversion layer formed beneath the SiO2:Si+/n-Si interface. The maximum white-light luminescent power is up to 60 nW at a pulsed bias current of 1.25 A. Next, the 4-nm Si nanocrystal (nc-Si) contributed to PL and EL at about 760 nm is precipitated in the plasma enhanced chemical vapor deposition (PECVD)-grown Si-rich SiOx film after annealing at 1100 °C for 30 min. Under a high RF power condition, the increasing substrate temperature usually inhibits the precipitation of nc-Si since high-temperature growth facilitates stochiometric SiO2 deposition. The indium-tin-oxide (ITO)/PECVD-grown SiOx/p-Si/Al MOS diode is highly resistive with turn-on voltage and power-current (P-I) slope of 86 V and 0.7 mW/A, respectively. The decomposed EL peaks at 625 and 768 nm are contributed by the bias-dependent cold-carrier tunneling between the excited states in adjacent nc-Si quantum dots. Both evaluated ITO/SiOx junction barrier height and Fowler-Nordheim (FN) tunneling threshold decreased from 3.7 to 1.1 eV and from 2 to 1.4 MV/cm, respectively. Low-plasma-power and oxygen-deficient deposited SiOx at 400oC provides nc-Si density of 6.4�e1018 cm-3, enhancing internal quantum efficiency and power-current slope of an ITO/SiOx/p-Si/Al MOSLED by one order of magnitude. Third, Structural damage enhanced near-infrared EL of a MOSLED made on SiOx film with buried nanocrystallite Si after CO2 laser rapid-thermal-annealing (RTA) at an optimized intensity of 6 kW/cm2 for 1 ms is demonstrated. Laser ablation is initiated at a laser intensity of >7.5 kW/cm2, leaving numerous luminescent centers that are related to NOV defects, increasing the absorption coefficient and related optical bandgap energy, and reducing the refractive index in partially annealed SiOx. CO2 laser RTA induced oxygen-related defects are capable of improving FN tunneling mechanism of carriers at metal/SiOx interface. The CO2 laser RTA SiOx film reduces FN tunneling threshold to 1.8 MV/cm, facilitating an enhanced EL power of an ITO/SiOx/p-Si/Al MOSLED up to 50 nW at a current density of 2.3 mA/cm2. Fourth, the premier observation on the enhanced light emission from such an ITO/SiOx/p-Si/Al MOSLED with Si nano-pyramids at SiOx/Si interface is demonstrated at low biases. The Si nano-pyramids exhibits capability in providing the roughness of the SiOx/Si interface, and improving the F-N tunneling mechanism based carrier injection through the novel SiOx/nano-Si-pyramid/Si structure. With these Si nano-pyramids at a surface density of up to 1E12/cm2, the F-N tunneling threshold can be reduce from 7 MV/cm to 1.4 MV/cm. The correlation between surface density of the interfacial Si nano-pyramids and the threshold F-N tunneling field has been elucidated. An output EL power of nearly 150 nW under a biased voltage of 75 V and current density of 32 mA/cm2 is reported for the first time. The last one is that nc-Si based MOSLED on Si nano-pillar array with size, height and density of 30 nm, 350 nm and 2.8E10 cm−2, respectively, is characterized. The nano-roughened Si surface contributes to both the relaxation of total-internal reflection at device-air interface and the FN tunneling enhanced turn-on characteristics, providing the MOSLED a maximum optical power of 0.7 uW obtained at biased current of 375 uA. The optical intensity, turn-on current and power-current slope of nc-Si MOSLED on high-aspect-ratio Si nano-pillar array are 140 uW/cm2, 5 uA, 2+-0.8 mW/A, respectively. A maximum external quantum efficiency of up 0.1% is reported.

The lifetimes of higher-lying excited states were measured for 16C and 23Ne using a target and degrader setup made of beryllium and gold to apply the Doppler-shift attenuation method. The experiment was performed at the Argonne National Laboratory exploiting the reaction 9Be(9Be,2p)16C* as well as 9Be(16O,2p)23Ne*, which was available due to oxidation of the target. The emitted gamma rays were measured with Gammasphere while the charged particles were detected with Microball. By comparing the measured gamma-ray spectra for different detection angles and 2p events with Geant4 simulations, lifetimes can be obtained. An elaborated explanation of the used analysis method and potential uncertainties is given in this work. The simulations were carried out for two different sets of stopping powers to check their influence on the results. For 23Ne the lifetimes of two higher-lying states could be measured for the first time. The lifetime of the (5/2+,7/2+) state at 2517 keV was obtained to 641(79)fs +16fs-6fs(syst,target), while the lifetime of the (5/2+, 7/2+) state at 1702 keV was obtained to 168(55)fs +8fs-1fs(syst,target) +72fs-80fs(syst,feeding). To consider the feeding for the lower state it was assumed that the angular distributions are the same for both observed transitions. Theoretical USDB calculations were able to reproduce the level energies well, while they significantly underestimate the experimental lifetimes. For 16C the lifetime of the 4_1+ state could be constrained between 1.9ps +0.0ps-0.1ps(syst,target) and 4ps. This results in 2.74e^2fm^4 ≤ B(E2;4_1+→2_1+ ) ≤ 5.78e^2fm^4 +0.32e^2fm^4 -0.00e^2fm^4(syst,target) as a transition strength limit for the 4_1+ state. Theoretical predictions from no-core shell model calculations with NN+NNN interactions and p-sd shell model calculations for several effective two body interactions fulfill this constraint. The most likely lifetime range for the 2_2+ state was obtained to be 244 fs to 376 fs. Together with branching ratio limits for this state, which are known from previous measurements, the transition strengths for the 2_2+ state could be constrained. No-core shell model, recent in-medium no-core shell model, and p-sd shell model calculations are compared to these results. In the second part of this work a conceptual design of a 14C electron scattering experiment at the QCLAM Spectrometer at the S-DALINAC is presented.

碩士
國立中央大學
材料科學與工程研究所
107
High-entropy alloys (HEA) attract great attention in past few decades. Most HEA researches mainly concentrate on the heavier multi-principal elements with equiatomic or near-equiatomic alloys. In this study, we focus on the light-weight and non-equiatomic medium-entropy alloys (MEA) system with low density (below 5g/cm3). Series of non-equiatomic quaternary alloy system, Ti-Al-Cr-Nb、Ti-Al-Cr-V were firstly designed by using calculating parameter (∆S、∆H、δr), then further modified into quinary Ti-Al-Cr-Nb-V alloy system. All samples were prepared by vacuum arc melting and rapidly cooling process. The XRD results of Ti-Al-Cr-Nb 、Ti-Al-Cr-V and Ti-Al-Cr-Nb-V MEA reveal the single BCC structure. The hardness value of Ti60-Al-Cr-Nb reduced from 480Hv to 365Hv with decreasing the Al content which implies that the ratio of Ti/ Al elements plays an important role on the alloy hardness. The optimum mechanical performance occurs at Ti60-Al-Cr-Nb-V MEA with tensile yield strength of 1009 MPa, fracture strength of 1223 MPa, and plastic strain of 27.1%. In summary. the Ti60-Al-Cr-Nb-V MEA not only possesses higher mechanical properties than the commercial Ti6Al4V alloy, but also has similar density, wear resistance, and oxidation behavior to commercial Ti alloys. Therefore, it is believed that the Ti60-Al-Cr-Nb-V MEA can be a promising light-weight structure material for the applications of transportation vehicles and sport equipment.

Exclusive neutron capture cross sections of 17C and associated stellar reaction rates have been derived from Coulomb dissociation of 18C using the R3B-LAND setup at GSI in Darmstadt (Germany). The secondary beam of relativistic 18C at approximately 430 AMeV was generated by fragmentation of primary 40Ar on a beryllium target. In the FRagment Separator (FRS) the nuclei of interest were selected and subsequently guided to the experimental setup at Cave C. There the ions were excited electromagnetically in the electric field of lead target nuclei and the de-excitation process was detected with the R3B-LAND setup. All reaction products of the one-neutron evaporation channel including gammas from de-exciting states of fragments were measured and the invariant mass was reconstructed. A similar measurement of 17C Coulomb dissociation served as a benchmark to validate the accuracy of the present results with respect to previously published data. The measured relative energy spectra of 18C Coulomb dissociation to the ground state of 17C as well as the first and second excited state in 17C qualitatively match theoretical calculations of the Coulomb- dissociation process in an independent-particle model. In particular, the shapes of experimental data are reproduced. The measured spectroscopic factors were compared to an exclusive one-neutron knockout measurement on 18C, which is consistent within the respective uncertainties. The energy differential cross sections were converted into photo-absorption cross sections 18C(γ,n)17C with virtual-photon theory. Subsequently, exclusive neutron-capture cross sections 17C(n,γ)18C to the ground state were derived using the detailed-balance theorem. The neutron-capture cross sections were used to calculate stellar reaction rates, where the neutron velocities follow a Maxwell-Boltzmann distribution. The results were compared to thermonuclear reaction rates from a statistical Hauser-Feshbach model (HF). The uncertainty of the experimental results is at maximum around 60% at T9 = 1 GK for neutron capture in the ground state of 17C. This is accompanied by an uncertainty of a factor of ten in the HF calculation.

碩士
國立交通大學
光電工程系所
93
The difference between white and near-infrared electroluminescences (EL) of the metal-oxide-semiconductor diodes fabricated on 1100oC-annealed Si-rich SiOx/p-Si substrate with buried pyramid Si quantum dots (Si-QDs) are characterized. By changing the substrate temperature and induced coupled plasma (ICP) power during the plasma enhanced chemical vapor deposition (PECVD) of Si-rich SiOx films, the effects of growth condition on the defect-related and Si-QD related carrier transport and EL spectroscopy are also investigated. By decreasing the ICP power to a threshold of 30 W, the (100)-oriented triangular Si-QDs significantly grows up the along Si/SiOx interface. From the power-dependent and temperature-dependent micro-PL spectra, it is concluded that the luminescent components at 700-850 nm is mainly contributed by the recombination in Si-QDs and self-trapped exciton (STE). After comparing the EL spectra of MOS diodes made on as-grown and annealed Si-rich SiOx, the Si-QD-related EL spectra at 650-850 nm is confirmed, whereas the EL spectra at shorter wavelengths (400-650 nm) is attributed to the radiative defects such as the weak-oxygen bond (415 nm), the neutral oxygen vacancy (NOV) defects (455 nm), and the E'delta defect (520 nm). These defects become an electron-preferred transporting path within the Si-rich SiOx film, whose densities are decreased with increasing substrate temperature or reducing ICP power. A nearly defect-free Si-rich SiOx sample can be grown under such condition, which contributes to a most stable near-infrared EL with longest lifetime although the power of purely Si-QD related EL at near-Infrared wavelengths is slightly lower (16 nW).

碩士
國立成功大學
電機工程學系
102
In our research, we fabricated SRO/SiO2 multilayer based device by hydrogen ion-source assisted sputtering.The luminescence mechanism of SRO were silicon nano-clusters and defect (E` center，NBOHC). The size of silicon nano-clusters with different hydrogen anode voltage by photoluminescence, raman and x-ray photoelectron spectrometer were discussion. Ion source provided energy to silicon atoms, and aggregated into silicon nano-clusters. Besides, it also produced more oxygen related defects, which improved EL efficiency . For hydrogen anode votage 116V, EL intensity increased 15 times,and EL efficiency enhanced 6 times when the power was operated at 30W. The EL luminescence mechanism of radiative recombination was through E` center and NBOHC. Defect recombination rates increased,and trap cross section decreased with the decreasing of temperature.For non ion source device, EL intensity reached maximum at 250K; For hydrogen anode votage 116V, EL intensity reached maximum at 123K

碩士
國立臺灣大學
光電工程學研究所
96
In this thesis, we study optoelectrical characteristics and material analysis of silicon-rich silicon nitride film (SRSN) with silicon nanocrystals (Si-ncs). The SRSN films are deposited by plasma enhanced chemical vapor deposition (PECVD) using SiH4 and N2 or NH3. Si-ncs embedded in Si3N4　would form after high temperature annealing. We conclude that NH3 is the better reactant gas instead of N2. The SRSN films with different composition are deposited by detuning NH3 fluence. From results by means of RBS, we gain the ratio of N/Si raise with NH3 increasing, and SRSN changes from Si-rich SiNx to pure Si3N4. This phenomenon is proved by means of FTIR, the absorption peak corresponds Si-H stretching mode shift toward long wavenumber. From images of HRTEM, we observe that the size of Si-ncs decrease with NH3 increasing. The photoluminescence (PL) ranges from 675 nm to 385 nm by quantum confinement effect (QCE). The strongest PL reveals from SiN1.16. In addition, we discuss the electroluminescence of SRSN LED. The low turn-on voltage is 3 V because of low barrier between metal and dielectric layer. However, the optical power just reaches 45 nW. As the result, we study the charge storage effect in SRSN LED. In capacitance-voltage and retention time measurement, we conclude electron and hole are hardly trapped in Si-ncs so that the efficiency of e-h recombination is low, compared to Si-rich silicon oxide (SRSO) LED.

碩士
國立臺灣大學
光電工程學研究所
99
In this thesis, the synthesis of a-SixC1-x films embedded with Si-ncs and SiC-ncs by fluence-ratio detuned PECVD at high-temperature growth is investigated to modify its luminescent property and to enrich the crystallinity after thermal annealing at 1100oC. With changing the deposition temperature from 450oC to 650oC, the Si concentration increases from 64.7% to 71.6%. However, the carbon and oxygen contents decrease from 27.7% to 22.8% and 7.6% to 5.5% and the O/Si ratio is reduced from 0.12 to 0.07 from the XPS analysis due to growth of better crystallinity to prevent the oxygen invasion in a-SixC1-x films. A significant signal at 510 cm-1 is shown to confirm the existence of Si-ncs after post-annealing. The other two intensive peaks at 744 and 933 cm-1 are red-shifted than bulk 3C-SiC Raman peaks at 796 (TO) and 972 cm-1 (LO) and ascribed to reduced nanograin size of SiC-ncs, respectively. From the results of XRD spectra, the average crystallite sizes of Si and 3C-SiC nanocrystals are around 4.2±0.5 nm and 2.4±0.3 nm, respectively. On the basis of FTIR analysis, the Si-H3 stretching mode is transformed into Si-H stretching mode after annealing since the hydrogen bond is broken up to diffuse out. Accordingly, Si-ncs can be easily aggregated by dehydrogenation in Si-H3 radical. A distinct band at 792-806 cm-1 is ascribed to Si-C stretching mode and the blue-shifted peak from 792 to 802 cm-1 is due to enhanced strength of bonds between Si and C atoms. The intense visible PL centered at 485 nm is found in annealed sample of g=60% and it attributed to the luminescence of SiC-ncs due to the self-trapped excitons at the surface states between SiC-ncs and surrounding. In addition, the PL peak at 580 nm is also observed from the contribution of Si-ncs in view of quantum confinement effect. Composition ratio x in SixC1-x is detuned from 0.74 to 0.62 with increasing fluence ratio from 40 to 70% by XPS spectra. The resistivity of P type a-SixC1-x network at g of 50% reduces to 2.2×101 Ω-cm when B2H6 doping mole fraction increases to 2% since the appropriate amounts of boron atoms occupy the position in tetrahedral SiC network to release enough holes to form the electrically active dopant after thermal process of 650oC. The dopant density is also increased to 1.35×1016 cm-3 when doping mole fraction is at 2% corresponding to activation energy of 0.17 eV. On the other hand, the resistivity is reduced from 22 to 0.72 Ω-cm and dopant density is increased from 1.35×1016 to 4.35×1017 cm-3 due to the minimization of the overdoping phenomenon to reduce the influence on excess impurity atoms scattering and collision between released carriers when enlarged triply doping gaseous fluence and it is equivalent to gaseous dilution owing to various dissociation energy for different process gas. The resistivity of N-SiC is decreased abruptly to 11.3 Ω-cm when RF power changes to 80 W corresponding PH3 dopant density of 1.46×1015 cm-3. The PIN thin film light emitting diode with intrinsic layer embedded with Si-ncs and SiC-ncs is fabricated to enlarge optical power, reduce turn on voltage and enhance carrier injection efficiency. Carrier injection and transport properties can be improved with the higher doping concentration P-SiC layer. The thicker intrinsic layer caused the larger series resistance thus whether turn on voltage or injection current is larger than the thinner I-layer and the optical power emitted from PIN TFLED with I layer thickness of 50 nm is triple than I layer thickness of 25 nm at g of 60%. With increasing thickness of intrinsic layer from 25 nm to 100 nm at g of 50% since the carrier tunneling probability is decreased with enlarging the intrinsic layer thickness since insufficient electric field across the I-SiC film is to reduce the carrier injection and the luminescent centers are more plentiful owing to the Si-rich SiC matrix at g of 50% with embedded more quantity of Si-ncs. The optical power from PIN LED with g of 50% at I layer thickness of 50 nm is three point five times than I layer at 25 nm. The PCR increasing trend is due to the production of more luminescent centers at thickness of 50 nm but subsequently decreased is owing to too thicker I-layer caused the carrier tunneling probability reduction. The EQE is larger twice than others with increasing intrinsic layer thickness from 25 to 50 nm at g of 60% and the P-I slope is four times than others since the trade off relation between carrier transport and tunneling into active layer and the more luminescent centers in active layer are observed thus the optimized thickness of intrinsic layer is 50 nm. The EQE is four times than others with increasing g of 50% intrinsic layer thickness from 25 to 50 nm and the P-I slope is six times than others since the appropriate intrinsic thickness at 50 nm is needed to enhance light emission and preserve the carrier injection ability. Carrier transport via band to band tunneling is confirmed owing to high electric field and then radiative transition is also occurred due to the carrier tunneling into intrinsic region and its neighborhood. The principal EL peak at 495 nm with narrower shape is assigned to self-trapped excitons at the surface states between SiC-ncs and surrounding at g of 60% corresponding to blue-white EL emission pattern. Moreover, the main EL wavelength centered at 570 nm with broader shape is attributed to nearly direct band to band transition by Si-ncs at g of 50% and consistent with orange-yellow EL emission pattern. The injection efficiency is six times than N-SiC with 1015 cm-3 when dopant density increased to 1016 cm-3. The EQE is enhanced nearly six times when injection efficiency is increased from 7.84% to 46 %.

碩士
臺灣大學
光電工程學研究所
96
In this thesis, correlation between N2O/SiH4 fluence ratio and O/Si composition ratio for optimizing Si nanocrystal precipitation in Si-rich SiOx grown by low-plasma PECVD is demonstrated. The O/Si composition ratio of SiOx can be adjustable from 1.38 to 0.88 by detuning N2O fluence and N2O/SiH4 ratio to obtain a nonlinearly Gaussian-like dependency with near-infrared photoluminescence (PL). By reducing N2O/SiH4 ratio, abundant Si-H bonds with absorption at 870 and 2250 cm-1 assist small-size Si nanocrystal precipitation and prevent outer surface re-oxidation. Maximum PL at 760 nm at O/Si=1.24 with corresponding Si concentration of 44.64 atom.% is obtained at N2O/SiH4 ratio of 5.5. In particular, the N2O fluence remains as small as 25 sccm to restrict oxygen desorption and to complete SiH4 decomposition, thus minizing the hydrogen passivation on dangling bonds at Si nanocrystal surface. The N2O:SiH4 fluence is decreased to 5:1 and the optimized annealing are achieved as short as 15 min at 1100oC in comparison with typical 1-hr process. HRTEM analysis reveals such tiny Si nanocrystals exhibit diameter of only 1.5±0.2 nm. From FTIR results, we conclude that the ultra-low fluence PECVD can completely decompose the Si from SiH4 with minimum hydrogen passivation, which facilitates the precise control of Si nanocrystal size and greatly enhances the blue PL intensity. The blue-light EL pattern is observed at 290 V for the MOSLED made on SiOx grown at N2O fluence as low as 25 sccm. The maximum emitting power is about 333~500 nW for the blue-light MOSLED as compared to that of 270 nW for red-light MOSLED associated with a PI slope of 0.37 mW/A. Higher output power of MOSLED on low-N2O-fluence grown SiOx is attributed to the smaller Si nanocrystals with larger density.

碩士
臺灣大學
農藝學研究所
98
Light is an important environmental factor controlling plant growth and development. In this study, it was observed that continuous white light can induce the wavy growth pattern of seminal roots in germinating rice (Oryza sativa L. cv. Taichung Native 1; TCN1) seeds. However, the phenotype of light-induced wavy root was genetic diverse among rice cultivars; for example, the light-induced wavy root could be presented in seedlings of indica type rice (such as TCN1), but could not be presented in that of japonica type cultivars (such as Tainung 67; TNG67). According to the experiment with plants partially exposed to light, it was suggested that the light signal for inducing the wavy roots were directly sensed by root tissues. Analysis of longitudinal sections of wavy seminal roots indicated that light-induced root waving was caused by the asymmetric cell growth on both side of vascular cylinder cells in the root tips. In addition to white light, red light (90 μmol m-2s-1) could also induce root curling phenotype on seminal roots. However; the blue light with high intensity (90 μmol m-2s-1) presented no effect on inducing root waving/curling. On the other hand, other results in our laboratory showed that low intensity (30 μmol m-2s-1) of blue light could induce root waving. Using Aspirin to inhibit endogenous jasmonic acid (JA) biosynthesis in TCN1 seedlings conducted the light-induced curling/wavy root phenotypes were absent. Furthermore, light effects on expressions of the genes involved in JA biosynthesis, i.e., allene oxide synthase (OsAOS) gene family and 12-oxophytodienoic acid reductase (OsOPR1), and a root specific JA-responsive gene, root specific rice PR10 (RSOsPR10) were observed. The data showed that transcript levels of most JA biosynthesis-related and JA-responsive genes were increased in white- and red-light conditions. Moreover, N-1-naphthylphthalamic acid (NPA), an inhibitor of auxin efflux carriers, was used to interrupt auxin polar transport in roots, and then the morphology of light-induced wavy root was eliminated. Thus, the results suggested that JA biosynthesis and auxin polar transport were essential for light-induced seminal root waving in seedlings of indica type rice.

博士
國立臺灣大學
農藝學研究所
102
Our objective in this study was to evaluate the effect of light quality on the morphology and photosynthetic physiology of rice seedlings. We examined the growth, development, and metabolic responses of rice seedlings to varying light quality firstly. Seedlings were hydroponically cultured under red (R) light-emitting diodes (LED), green LED (G), blue LEDs (B), and red + blue LED (RB) inside growth chambers. Red light induced shoot elongation. B light inhibited shoot elongation and promoted health index values. B light also resulted in higher total protein content in tested leaves compared to RB. Blue light enhanced the effective quantum yield of PSII photochemistry (ΦPSII) and photochemical quenching (qP) while reducing non-photochemical quenching (NPQ) in seedling leaves. The responses of rice seedlings to green and red light were quite similar. The anthocyanin content of seedling leaves was observed to be highest in RB but less so in R and B, the latter two being even lower than in G. Different wavelengths mediated the chlorophyll (Chl) a/b ratio of the leaves. Light quality influenced photosynthetic potential and nitrogen metabolism, which are related to water-use efficiency (WUE) and nitrogen uptake. We further investigated the response of time-integrated WUE, 13C discrimination (Δ13C), and nitrogen uptake in hydroponic seedlings of rice grown under different light treatments with fluorescent light (FL) as the control. The WUE response was highest for seedlings grown under R light, then (in decreasing order) seedlings grown under G, RB, and B light. WUE had a significantly positive correlation with Δ13C except under FL light (P<0.01). Nitrogen content (%N) and δ15N values were used to estimate the effects of fertilizer uptake under different lighting conditions. The amount of N in seedlings derived from fertilizer (Nf) was highest under B light and lowest under R light. Therefore, we conclude that blue light may increase stomatal conductance and transpiration, decrease WUE, and promote root N uptake. The dynamics of Chl, biosynthetic intermediates (protoporphyrin IX, PPIX; magnesium protoporphyrin IX, MGPP; protochlorophyllide, Pchlide), degradation intermediates (chlorophyllide, Chlide; pheophytin, Phe; pheophorbide, Pho), and carotenoids (Car) in leaves of rice seedlings were also investigated. Lower levels of Chl and Car in leaves were observed under G lighting. Light quality did not mediate the mole percent of porphyrins in biosynthetic pathways. Lower Phe/Chlide ratios were observed under G and FL lighting conditions, indicating that green-enriched environments may up-regulate the Chlide degradation route in leaves. In order to clarify the effect of green light on the Chl degradation pathway, seedlings were grown under equal intensity (40 μmol m-2 s-1) of red and blue light with four levels of green light intensity (0, 20, 40, and 60 μmol m-2 s-1). Some morphological traits and photosynthetic physiology were also investigated at the same time. Sheaths of rice seedling leaves became elongated and leaves grew more erectly under red and blue light with increasing green light intensity. These morphological traits are known as shade avoidance symptoms (SAS). Lower Chl, decreasing &;#1060;PSII, and increasing NPQ were also observed under increasing green light intensity. Higher Chlide levels and lower Phe/Chlide ratios were observed under increases in green light intensity. These results indicated that green light induced SAS and mediated Chl degradation routes in rice seedlings.

博士
國立臺灣大學
生物產業機電工程學研究所
95
One of the objectives of this research was to develop a near-infrared (NIR) imaging system that would detect rice intrinsic qualities nondestructively in real time rice processing lines. The sorting of a single rice kernel based on intrinsic qualities will precisely influence the classification and packaging process of rice. Therefore, the other objective of the research was to develop a rice moisture detecting system for single rice kernel. The developed NIR imaging system consists mainly of a NIR CCD camera which is coupled to a camera controller. A frame grabber board was used to receive the video signal from the camera. A filter exchange device consisted of a filter adapter, a filter holder, and a stepper motor module that was combined with the CCD camera. The filters were installed in a filter holder. The filter exchange device was controlled by a stepper motor in order to rotate automatically such that the NIR imaging system can effectively acquire multi-spectral images. In this work, calibration methods including multiple linear regression (MLR), partial least squares regression (PLSR), and artificial neural network (ANN) were used in both of near-infrared spectrometer (NIRS) and NIR imaging system to determine the moisture and protein contents of rice. Comprehensive performance comparisons among MLR, PLSR, and ANN approaches were conducted. To reduce repetition and redundancy in the input data and obtain a more accurate network, six and five significant wavelengths selected by the MLR model, which had high correlation with the moisture and protein contents of rice, were used as the input data of the ANN. The performance of the developed system was evaluated via a series of experimental tests for rice moisture and protein contents. Utilizing three models of MLR, PLSR, and ANN, the rice moisture analysis results of rval2, SEP, and RPD for the validation set were within 0.942-0.952, 0.435-0.479%, and 4.2-4.6, respectively. The prediction of protein content with the NIR imaging system by employing the same three models achieved rval2 of 0.769-0.806, and SEP of 0.266-0.294%, respectively. While compared with a commercial NIRS, experimental results showed that the performance of the NIR imaging system was almost the same as that of NIRS. Using the developed NIR imaging system, all of the three different calibration methods (MLR, PLSR, and ANN) provided satisfactory prediction of rice moisture and protein content. These results indicated that the NIR imaging system developed in this research can be used as a device for the measurement of rice moisture and protein content. A NIR light-emitting diode (LED) individual rice kernel moisture content measurement system contains NIR LED, rice moving chute, detecting units, and signal processing unit was also developed in this research. A calibration set which contained 78 rice kernels with moisture content ranged from 10.34-22.37% was used to calibrate the system and to develop a prediction equation. Another set of rice which containing 60 kernels with moisture content range of 10.50-21.65% was used for validation. The coefficients of determination for the calibration and validation sets based on 940, 1,050 and 850 nm LED were 0.706 and 0.624, respectively. The results indicated that the developed NIR LED measurement system can be utilized on the rice processing line.

碩士
國立臺灣大學
農藝學研究所
103
Light is not only the energy source for plants, but also an environmental signal to modulate plant morphogenesis. Our previous research showed that TCN1 (Oryza sativa L. cv. Taichung Native 1; an indica-type rice variety) displayed a wavy root phenotype under light conditions, but TNG67 (Oryza sativa L. cv. Tainung 67; a japonica-type rice variety) displayed a straight root phenotype. Moreover, nitric oxide, oxylipins, ethylene, and auxin were sequentially involved in the signaling cascades of light-induced root waving. In this study, we tried to clarify the mechanism leading to varietally dissimilar seminal root photomorphogenesis. Our results showed that TCN1 was more sensitive to light stimulus and following downstream signaling molecules. Moreover, the levels of light-induced inhihibition of root elongation, gene expression of OsHY5, and biosynthesis of signaling molecules in TCN1 could be higher than those in TNG67. In addition, the gene expression patterns of some photoreceptors (OsPHYs, OsPHOT1a, OsPHOT1b) were correlated to the root phenotypes between varieties under light or dark condition. The effects of the specific wavelength of light on root waving induction were also identified. The results showed that root waving can be induced by red-green-blue and green-blue light. The gene expression patterns of OsPHOT1a and OsPHOT1b were correlated to the root phenotypes under different light qualities. For evaluation of environmental significance of different root morphogenesis; however, it was found that TCN1 seedlings under light or dark conditions performed same anchorage strength. On the other hand, TNG67 seedlings under light condition performed weaker anchorage strength than under dark condition.

碩士
國立臺灣大學
農藝學研究所
93
Light is one of crucial environmental factors affecting rice yield and quality. The purpose of the present approach was to study the effects of light on the quality formation of rice grains, utilizing proteomic related techniques. Three quality rice cultivars were grown in a phytotron and shading（50％）treatment were performed at flowering stage. Rice grains were sampled at 6 days, 15 days and mature after flowering（DAF）for analysis. Physiological characteristics, yield traits, and physical-chemical properties of rice grains were determined. For molecular analysis, changes of proteome expression pattern were monitored by one or two dimension electrophoresis（SDS-PAGE or 2-DE）. Differential expressed proteins were selected for putative function identification using MALDI-TOF and ESI-Q-TOF. The relationships between functions of proteins and the effects of light intensity on rice grain quality were analyzed and discussed. The results showed that, plant growth and all physiological processes were slowed down under shade. Cultivar TCS10 was more sensitive to the light intensity reduction than Koshihikari and TK9. Under shading treatment, three cultivars panicle and grain weight accumulation rate was slow down. Chlorophyll content (SPAD value) was decreased, and photosynthesis activity was dropped by about 50%. Under shading the time to mature was prolonged for about one week, suggesting more heat units is necessary to complement the low light effect. Low light intensity increased grain protein content and decreased amylose content. In physical-chemical related properties revealed by RVA, peak viscosity, breakdown, and final viscosity were decreased by low light treatment. In proteomic analysis a total of 400 to 500 protein spots could be resolved by 2-DE gels. Expression patterns of protein spots for three cultivars were significantly affected by shading. More than 30 differential expressed proteins were selected, identified with their pI and mass, and quantified. During rice grain development the amount of 7 proteins in Koshihikari, 18 proteins in TCS10 and 10 proteins in TK9 were increased. And the levels of 20 proteins in Koshihikari, 5 proteins in TCS10 and 14 proteins in TK9 were decreased during rice grain development. Shading increased the expression of prolamins, glutelins, G3PDH, FBPA, and alanine aminotransferase, but decreased the expression of glyoxalase I, cytoplasmic malate dehydrogenase, glycogen starch synthase, and several allergen proteins. The decrease of glycogen starch synthase might be associated with the decrease of amylose content of rice grains grown under low light. And the increase of the amount of glutelins and prolamins may influence the physical-chemical characteristics of rice flour. In conclusion, the present study provided a proteomic and functional basis that can be used as a tool to monitor and rationalize the effect of light on the rice grain quality formation.

碩士
國立中興大學
食品科學系
93
Abstract Taichung Sen 10 brown rice was used for this study. Brown rice was germinated by treating with either normal light or Far Infrared Rays (FIR) for eighteen or twenty-one hours inside 25℃ incubator. The slightly germinated brown rice dealt by freeze dries. The objective of this study was to evaluate the change of physicochemical properties and anti-oxidative activity of germinated brown rice induced by two source of light. Germination observed in all treatments. The water content was about 40% after germination and reduced would be to 5.83~6.24% after freeze dried. Meanwhile the water activity would be lower than 0.5. So, it could take control on the quality of rice. In addition, the increment of dry weight was about 8% The α-amylase activities of germinated brown rice treated with FIR were higher than with normal light and increased with the germinate time. And, the α-amylase activities of germ were higher than of kernel. There was no significant difference in reducing sugar and total dietary fiber. The quantities of necessary amino acid and GABA were raise after germination. The nutritive value of total storage proteins were increase significantly. Each FIR treatment and long time would consume the quantity of vitamin E. The chelating ability of ferrous and TEAC in rice and germ after FIR treatment showed the higher level than after normal light, and increased with germinate time. The scavenging ability of DPPH free radical and superoxide radical, as well as the reducing power were showed the same tendency that the value would increase with germinate time in rice kernel, and FIR treatment had the better results than the treatment of normal light. After FIR treatment with 21 hours could obtain the better result in all antioxidant ability.

By studying crown structure, leaf area index (LAI), and light interception during the first 3.5 years of development, I assessed the patterns of above-ground space partitioning and stand dynamics in monocultures and mixtures of three tree species (Cedrela odorata, Cordia alliodora, and Hyeronima alchorneoides). Plantations were established in the tropical rain forest of Costa Rica. To understand species differences during the period of free growth, I measured leaf distribution, crown shape, and biomass allocation strategies of each species at age one year. To compare stands dynamics among monocultures and mixtures I obtained the size, crown shape, and relative position of plants at regular time intervals between age 1.5 and 3.5 years. Stand-level measurements of LAI, and canopy light transmission complemented these individual-tree measurements. Before the onset of competition, there was a statistically significant multivariate difference in crown architecture among the three species. The mean dry biomass (grams/tree)was 990.0 in Cedrela, 665.3 in Cordia, and 1281.4 in Hyeronima. Proportionally Cedrela allocated more biomass into roots than the other two species. Biomass allocation within crowns was correlated with specific above-ground architecture. Differences in stand composition caused major modification in several morphological traits. On average, the performance of Cordia and Hyeronima individuals growing in mixtures exceeded that observed in monocultures. Cedrela showed an opposite trend with larger trees in monocultures than in mixtures showing the effect of suppression in mixtures. At age 2.0 years monocultures had almost reached their maximum LAI values. Approximate LAI values were 4.5 for Hyeronima and 2.0 for the other two monocultures. LAI of the mixtures increased from 2.0 at age 1.5 years to 4.0 at age 3.5. At the end of this study a two-stratum canopy had developed in mixed-species stands with the shade-intolerant Cordia above both the gap-dependent Hyeronima and the suppressed Cerela. Thus, Cordia and Hyeronima showed compatible height growth and crown structural characteristics in mixtures. The growth patterns of mixed stands suggests that both inter-specific competition with neighboring trees and infections by shoot-boring larvae of a lepidopteran species are responsible for the suppression of Cedrela.