Dissertations / Theses on the topic 'Growth of vegatation area'

A Work Project, presented as part of the requirements for the Award of a Masters Degree in Finance from the NOVA – School of Business and Economics
Predicting GDP growth is a concern of several economic agents. The right way to model such variable is far from consensual. This paper’s goal is to compare different models for GDP growth forecasting in the euro area. For comparative purposes, an autoregressive model (which is used as benchmark) and two Autoregressive Distributed Models (ADL), which contain financial and non-financial variables, chosen based on the literature, are used. The main conclusion is that the ADL(2,1,1) considered has superior forecast performance in- and out-of-sample, although in this last case depending on the evaluation metric.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 147-159).
The goal of this thesis is to develop and understand processing conditions that improve the surface morphology and reduce the dislocation density in limited-area heteroepitaxy of Ge and SiGe on Si (100) substrates. Low pressure chemical vapor deposition was investigated for two limiting cases of strain states: thin, strained, high Ge content SiGe films for transistor applications, and thick, relaxed Ge films, for potential optoelectronic applications. Selective epitaxial growth of thin, high Ge-content, strained SiGe on oxide-patterned silicon was studied, specifically the effect of growth area on the critical thickness. The critical thickness of Sio.33Geo.67 formed by selective epitaxial growth in areas of 2.3 x 2.3 [mu]m was found to be 8.5 nm, which is an increase of 2x compared to the critical thickness observed for growth in large areas (i.e. for non-selective epitaxy). The sources of misfit dislocation nucleation in selective growth were analyzed, and misfit generation from the SiGe pattern edges, due to effects such as local strain concentration, Si surface shape near the oxide boundary, and preferential SiGe growth near the pattern edge were investigated. Thin, smooth Ge-on-Si films were developed and the effect of growth conditions on film morphology was examined to find an optimum temperature and pressure for smooth film surface (365 °C and 60 torr). A period of delayed epitaxial growth, or "incubation time" was observed, and a Si surface treatment technique, consisting of a short SiGe pulse, with negligible SiGe thickness, was employed to realize uniform Ge films with low surface roughness (RMS<0.3 nm) and reduced incubation time (<20 seconds). For selective growth of relaxed, thick Ge, approximately 1 pm-thick Ge films were grown in exposed Si regions on oxide-patterned wafers, and germanium selectivity, faceting, surface roughness and threading dislocation density were studied as functions of growth and processing conditions. The optimal growth condition for relaxed Ge selective epitaxial growth was found (750 °C and 10 torr, with 100 sccms of GeH4 and 10 slpm H2 flow), and the effect of thermal annealing, Ge film thickness, and growth area on the threading dislocation density was also studied.
by Meekyung Kim.
Ph.D.

This thesis revisits the issue of business cycle synchronisation in the Euro area by utilising time-series models that may overcome some of the drawbacks in the existing literature. Two major contributions are made to the existing literature of evaluating cycle synchronisation. First, instead of identifying turning points from individual macroeconomic timeseries, as carried out in most studies, this thesis obtains turning points from multivariate information. It is hoped that including more variables containing business cycle information in the dating process may produce more accurate turning points and, in turn, improve the accuracy of measuring cycle correlation. In doing so, both parametric and non-parametric business cycle dating procedures are used. These include the quarterly Bry-Boschan (BBQ) algorithm, a single dynamic factor model and the Markov switching dynamic factor model. Second, unlike the traditional approach that measures growth cycle synchronisation in the euro area by calculating pairwise cycle correlations, this thesis analyses the degree of growth cycle co-movement within a multivariate setting by using a VAR model with cointegration.

Selective area growth of III-V semiconductor compounds using molecular beam epitaxy (MBE) has been envisaged as an in situ fabrication method for integrated circuits on a nanometer scale. However, conventional selective area growth techniques using MBE are limited to only two dimensional, template-like, pattering of the epilayer. The work presented in this dissertation describes the selective area growth of AlGaAs based structures using a Ga⁺ focused ion beam (FIB) as one of the group III matrix element sources in a MBE growth chamber. Since stoichiometric epitaxy of a III-V semiconductor compound can be achieved with an excess supply of the group V element, supplying the Ga matrix element as a FIB, under standard MBE growth conditions, was shown to facilitate a maskless, in situ, lateral selective area growth technique for GaAs. Consequently, this FIB-MBE growth technique, FIMBE, has the potential of exploiting the precise control over the elemental composition afforded by MBE in the growth (z) direction with the high spatial resolution of FIB technology in the lateral (xy) plane. Moreover, it offers the unique facility of growing fully integrated three-dimensional structures into one as-grown epilayer structure. The necessary modifications required to a standard FIB column and MBE growth chamber to fully exploit the combination of these two technologies, along with the operational performance of the fully integrated FIMBE growth system are presented. A study of the effect of incident ion energy (E_ion) on the film growth rate identified two growth rate limiting processes; (i) the inherent properties of the Ga⁺ FIB (E_ion <25eV) and (ii) material sputtering from the growing GaAs film (E_ion>100eV). However, a systematic reduction in the surface roughness of the FIMBE grown GaAs films was observed with increasing incident ion energy.

Graphene has unrivalled properties and is heralded as a revolutionary material for the 21^st century. Chemical vapour deposition (CVD) on metals is a promising method to produce large-area graphene. Controlling the properties of CVD graphene is vital for its integration in a wide-range of future applications. Many factors can influence the CVD growth of graphene and its properties, therefore further investigations will be beneficial to fully understand and control this technique. In this thesis I expand the knowledge about the growth of pure and heteroatom-doped graphene by low pressure chemical vapour deposition (LPCVD) and atmospheric pressure chemical vapour deposition (APCVD) on commercially available Cu and Pt foils. Using a range of characterisation techniques, I investigate the influence of the substrate’s properties and the synthesis conditions on the growth of graphene, in pursuit of improved, controlled or optimised production, which can promote high quality, large-area, single-layer graphene, or other as desired. By characterising the topography, surface roughness, crystallographic orientations, and chemical composition of six Cu foils, I find that their properties vary greatly and this influences the growth of CVD graphene. I elucidate that the commonly used 99.8 % Alfa Aesar Cu foil has a surface coating composed of calcium, chromium, and phosphorus, which detrimentally influences graphene growth. Cleaning Cu foils with CH₃COOH is shown to reduce the concentration of surface contaminants, consequently reducing the nucleation density and increasing the growth rate of CVD graphene. I also demonstrate that the shape, orientation, edge-geometry and thickness of CVD graphene domains can be controlled by the Cu crystallographic orientations. Single layer LPCVD graphene domains align with zigzag edges parallel to a single <101> direction on Cu{111} and Cu{101}, while bilayer domains align to two directions on Cu{001}. Hexagonal APCVD domains also preferentially align with edges parallel to the <101> direction(s). This discovery resolves a key challenge of controlling the orientation of individual graphene domains and opens a new avenue for tailored production of large-area CVD graphene with improved properties. By controlling the synthesis conditions of APCVD graphene on Pt foils I optimise production of ~0.5 mm single layer graphene domains with reduced nucleation density and increased growth rate of ~100 μm/min by synthesis at 1150°C, a higher temperature than previously reported. The absence of large, hexagonal, single-crystal domains on pristine Pt foil, and observation of a reaction between quartz and Pt that promotes hexagonal domains, suggests that a silicon or platinum silicide surface layer may be advantageous for improved growth of graphene. Finally, I demonstrate that the dopant concentration of nitrogen-doped graphene is increased at lower synthesis temperatures and higher NH₃ concentration, up to 1.3 %, but with an associated decrease in the growth rate. Direct visualisation, elemental confirmation, and electronic characterisation of individual nitrogen atoms is shown for the first time using aberration corrected scanning transmission electron microscopy and electron energy loss spectroscopy. Boron-doped graphene is also synthesised. The implications of these findings, and many additional minor contributions, are wide-ranging and of considerable importance for the future understanding of CVD growth of graphene on metals, and more generally for the advancement of scientific knowledge for manufacturing large-area graphene. Collectively, these discoveries represent a significant body of work that can improve the efficiency of production and assist with controlling the properties of large-area CVD graphene.

The sluggish development of corporate lending has remained the central concern of EU monetary policy makers as it is considered to hinder seriously the resurgence of growth. This paper looks at the development of loans to large corporations vs SMEs in the pre-crisis and post-crisis period and wishes to answer: (i) to which extent do allocated loan volumes actually contribute to Output growth? (ii) which factors determine the development of loans, considering above all loan interest rates? and (iii) what causes differences in loan interest levels across the EA? The results indicate that different loan developments in the EA explain very well differences in output development, loans to SMEs contribute even more to output growth than those for large corporations. Loan development itself is negatively influenced by the interest level which differs significantly across EA members, with small loans in addition always being charged an interest premium over large loans. The capitalization of banks, the size of banks and their internationalization play a role as well. A part of the sluggish growth of loans can be explained by the increasing use of alternative financial instruments by large firms. Interest rates in turn are following the ECB interest rate, - but this link has become looser in the post-crisis period, and long term government bond rates. Different risks faced by banks and different bank structures have become important explanatories of interest rates in the post-crisis period. (author's abstract)
Series: Department of Economics Working Paper Series

Thesis (PhD)--Stellenbosch University, 2002.
ENGLISH ABSTRACT: A community-based growth monitoring (GM) project was established in a rural village in KwaZulu-Natal. The project is an example of community-based activities that were based on a participatory approach of problem assessment and analysis. The first phase of the study comprised of a situation assessment. The aim was to evaluate the nutritional status and related factors of children aged 5 years and younger. It included a cross-sectional survey (questionnaire and anthropometric measurements), focus group discussions and interviews with key informants. From a nutritional point of view, the situation assessment identified a need for regular GM of infants and small children, increased availability of foods rich in micronutrients, and nutrition education. Relevant findings of the situation assessment were used during a project planning workshop that was attended by community representatives. The community's concern about the health of the preschool children and the lack of health facilities, and the need for regular weighing of their children prompted the establishment of a community-based GM project. The GM project was run by nutrition monitors, through home-based centres (named Isizinda). Monthly activities at the Isizinda included GM, nutrition education, and recording of morbidity and mortality data. Children who were either in need of medical attention or showed growth faltering were referred to the nearest clinic. During the latter half of the study, the GM project was integrated with a household food production project and the Isizinda served as promotion and training centres for agricultural activities. Project activities were continuously monitored by reviewing the attendance register, scrutinising the Isizinda files, observation and staff meetings. Community meetings (at least twice a year) allowed for two-way feedback and addressing questions and concerns. Acceptability of the GM activities was measured in terms of attendance and maternal perceptions. The coverage of the Isizinda project was estimated at approximately 90% and at least 60% of these children were adequately covered. The Isizinda data showed an equal distribution of child contacts over the various age categories and was representative of the community. The attendance data suggest that community-based GM is a viable option to be used for screening and nutrition surveillance, and as platform for nutrition education. Most mothers comprehended the growth curve. Positive behavioural changes have been observed in the community and the Isizinda data showed a steady decline in the prevalence of diarrhoea. The Ndunakazi mothers were appreciative towards the Isizinda project because of a better understanding of the benefits of regular GM. They expressed a sense of empowerment regarding the knowledge that they have gained. The community had a strong desire for the project to continue. The Isizinda project showed that community-based GM can provide the infrastructure for developing capacity for agricultural activities within the community. Data from the household food production project showed that maternal knowledge regarding nutritional issues can be improved through nutrition education given at the GM sessions and that, when GM is integrated with agricultural activities, a significant improvement in child malnutrition can be obtained. The Isizinda project falls within the framework of the Integrated Nutrition Programme, and can bridge the gap in areas which lack health facilities.
AFRIKAANSE OPSOMMING: ’n Gemeenskaps-gebaseerde groeimoniteringsprojek is tot stand gebring in ’n landelike gebied in KwaZulu-Natal. Die projek is 'n voorbeeld van gemeenskapsgebaseerde aktiwiteite wat gebaseer was op 'n deelnemende benadering van probleem bepaling en analise. Die eerste fase van die studie was a situasie analise. Die doel was om die voedingstatus en verwante faktore van kinders 5 jaar en jonger te bepaal. Dit het 'n dwarssnit opname (vraelys en antropometriese metinge), fokus groep besprekings en onderhoude met kern persone ingesluit. Uit 'n voedingsoogpunt het die situasie analise 'n behoefte vir gereelde groeimonitoring van babas en klein kinders, verhoogde beskikbaarheid van voedsels ryk in mikronutriente and voedingsvoorligting aangedui. Toepaslike bevindinge van die situasie analise was gebruik tydens ’n beplannings werkswinkel wat deur verteenwoordigers van die gemeenskap bygewoon is. Die gemeenskap se besorgdheid oor die gesondheid van voorskoolse kinders en die gebrek aan gesondheidsfasilitieite, asook hul behoefte om hul kinders gereeld te laat weeg, het aanleiding gegee tot die totstandkoming van ’n gemeenskaps-gebaseerde groeimoniteringsprojek. Die program is gedryf deur monitors deur tuisgebaseerde sentrums (genoem Isizinda). Maandelikse aktiwiteite by die Isizinda het groeimonitering, voedingvoorligting en die insameling van morbiditeit en mortaliteit inligting ingesluit. Kinders wie mediese sorg benodig het of wie groeivertraging getoon het, is na die naaste kliniek verwys. Die groeimoniteringsprojek is tydens die laaste helfte van die studie met ’n huishoudelike voedselproduksieprojek geintegreer en die Isizinda het as promosie- en opleidingsentrum vir die landbou aktiwitiete gedien. Projek aktiwiteite is deurgaans gemonitor deur die bywoningsregister en Isizinda leêrs deur te gaan, waarnemings en personeel vergaderings. Vergaderings met die gemeenskap (ten minste twee per jaar) het voorsiening gemaak vir wedersydse terugvoering en die aanspreek van vrae en besorgdhede. Die aanvaarbaarheid van die groeimoniterings aktiwiteite is gemeet in terme van bywoning en persepsies. Die Isizinda projek het ongeveer 90% van die kinders gedek, van wie ten minste 60% voldoende gemoniteer is. Die Isizinda data het ’n eweredige verspreiding van besoeke oor die verskillende oudersdomgroepe aangetoon. Die Isizinda data was ook verteenwoordigend van die gemeenskap. Die bywoningssyfers dui aan dat gemeenskapsgebaseerde groeimonitoring 'n lewensvatbare opsie is vir sifting en voeding opnames, en as 'n platform vir voedingvoorligting. Meeste moeders kon die groeikaart interpreteer. Positiewe gedragsveranderinge is in die gemeenskap waargeneem en die Isizinda data het ’n geleidelike afname in die voorkoms van diarree getoon. Die Ndunakazi moeders was waarderend teenoor die Isizinda projek as gevolg van 'n beter begrip ten opsigte van die voordele van gereelde groeimonitering. Hulle het 'n gevoel van bemagteging uitgespreek ten opsigte van hul verbeterde kennis. Hulle was mening dat die projek moes voortgaan. Die Isizinda projek het aangetoon dat gemeenskapsgebaseerde groeimonitoring die infrstruktuur kan skep vir die ontwikkeling vir kapasiteit vir landbou aktiwiteite binne die gemeenskap. Inligting van die huishoudelike voedselproduksieprojek het aangetoon dat die moeders se kennis ten opsigte van voedings verwante aspekte verbeter kan word deur voedingvoorligting wat gegee word tydens die groeimonitering sessie en dat, as groeimonitoring geintegreer is met landbou aktwiteite, 'n verbetering in die voedingstatus van die kind verkry kan word. Die Isizinda projek val binne die raamwerk van die Geintegreerde Voedingsprogram en kan die gaping dek in areas waar geen gesondheidsfasilteite is nie.

Since Shuji Nakamura, Hiroshi Amano, and Isamu Akasaki won the 2014 Nobel prize in Physics owing to theircontributions on the invention of efficient blue GaN light emitting diodes, GaN became an even more appealingmaterial system in the research field of optoelectronics. On the other hand, quantum structures or low-dimensionalstructures with properties derived from quantum physics demonstrate superior and unique electrical and opticalproperties, providing a significant potential on novel optoelectronic applications based on the employment of quantumconfinement.   In 2012, our research team at Linköping University utilized pyramid templates, which is an established approach toform quantum structures, to successfully grow GaN pyramids with InGaN hybrid quantum structures, includingquantum wells, quantum wires, and quantum dots. This growth enabled site-controlled pyramids based on selectivearea growth (SAG). After numerous studies on the photoluminescence properties, the mature and controlled growthtechnique was proposed to be adapted for fabrication of AlGaN pyramids on which GaN hybrid quantum structurescan be hosted.   This thesis is dedicated to the subsequent problems of the growth of AlGaN pyramids. It was found that there wasan undesired deposition of a considerable thickness on top the desired AlGaN pyramid with GaN multiple quantumwells. In this thesis, two different directions are explored to find the key solution with a potential of furtheroptimization. On one hand, the growth parameters such as precursors cut-off, carrier gas during cooling, temperatureholding, cooling pressure, III/V ratio, and the possible effect of GaN surfaces are investigated. However, due to theactual inherent properties of the metal-organic chemical vapor deposition reactor used, no promising parameter tuningcan been identified. On the other hand, from post-growth point of view, a KOH aqueous etching solution exhibits apositive result toward removing the undesired deposition. This etching process is suggested to be further optimized toachieve the final goal of eliminating the undesired deposition.

Prior studies have revealed that recent Asian and Hispanic immigrant entrepreneurs have made significant contributions to social change in the United States. Although African immigrant entrepreneurs have made such contributions, few studies exist about them, and there is limited knowledge about this business community. The purpose of this qualitative case study was to identify the barriers of growth in Ethiopian and Eritrean immigrant-owned firms in the Washington, DC area who were in business for a minimum of 3 years and represented various trade lines and geographical locations. The enhanced integrated model of ethnic business development, which proposes growth strategies by analyzing the interaction of opportunity structures, ethnic resources, and entrepreneurial and management skills, was used as the conceptual framework to guide this study. Semistructured interview data were gathered from the business owners and then analyzed by employing a pattern matching technique. The data analysis revealed the themes of management deficiencies and the lack of organizational support system as the main growth barriers of the firms studied. These findings suggested the improvement of management skills and the creation of an organizational support system. This effort demands a collaboration of public, private, and community organizations. The results of this study may have positive social change implications to local economies by facilitating the growth of immigrant-owned businesses and enhancing their job and income-creating potential.

This dissertation considers Small Area Estimation with a main focus on estimation and prediction for repeated measures data. The demand of small area statistics is for both cross-sectional and repeated measures data. For instance, small area estimates for repeated measures data may be useful for public policy makers for different purposes such as funds allocation, new educational or health programs, etc, where decision makers might be interested in the trend of estimates for a specic characteristic of interest for a given category of the target population as a basis of their planning. It has been shown that the multivariate approach for model-based methods in small area estimation may achieve substantial improvement over the usual univariate approach. In this work, we consider repeated surveys taken on the same subjects at different time points. The population from which a sample has been drawn is partitioned into several non-overlapping subpopulations and within all subpopulations there is the same number of group units. The aim is to propose a model that borrows strength across small areas and over time with a particular interest of growth profiles over time. The model accounts for repeated surveys, group individuals and random effects variations. Firstly, a multivariate linear model for repeated measures data is formulated under small area estimation settings. The estimation of model parameters is discussed within a likelihood based approach, the prediction of random effects and the prediction of small area means across timepoints, per group units and for all time points are obtained. In particular, as an application of the proposed model, an empirical study is conducted to produce district level estimates of beans in Rwanda during agricultural seasons 2014 which comprise two varieties, bush beans and climbing beans. Secondly, the thesis develops the properties of the proposed estimators and discusses the computation of their first and second moments. Through a method based on parametric bootstrap, these moments are used to estimate the mean-squared errors for the predicted small area means. Finally, a particular case of incomplete multivariate repeated measures data that follow a monotonic sample pattern for small area estimation is studied. By using a conditional likelihood based approach, the estimators of model parameters are derived. The prediction of random effects and predicted small area means are also produced.

Mestrado em Economia
Nas últimas décadas surgiu um crescente interesse na literatura econômica em relação à pergunta de como a desigualdade está relacionada com o crescimento econômico. Nenhum consenso foi conseguido ainda. Uma resposta confiável pode ajudar os decisores políticos a conceber políticas de distribuição que melhorem o crescimento econômico. Este artigo analisa a relação entre a desigualdade e o crescimento para os países da zona euro, através do cálculo do coeficiente de Gini acumulado no crescimento do PIB per capita. Além disso, o ajuste dos canais do mecanismo de transmissão é analisado em termos de correlação e causalidade. Este artigo faz uso dos estimadores OLS, FE e System GMM, ao usar os testes de causalidade de Granger para verificar a direção causal das variáveis de interesse. Foi encontrada evidência para uma relação insignificante, mas ligeiramente positiva entre a desigualdade e o crescimento econômico na zona euro. Os países com mais desigualdade experimentaram em média um crescimento menor, mas mais prolongado no tempo. Além disso, apenas três das 11 hipóteses relativas ao mecanismo de transmissão foram confirmados pelos dados em analise.
In past decades rising interest in economic literature has emerged concerning the question of how inequality is related to economic growth. No consensus has been reached yet. A reliable answer might help policy makers to design distributional policies that improve economic growth. This paper analyses the relationship between inequality and growth for euro area countries by regressing the Gini coefficient on accumulated GDP per capita growth and growth spells. Moreover, the fit of channels from the transmission mechanism to data is analysed in terms of correlation and causality. This paper makes use of OLS , FE and System GMM estimators, while using Granger causality tests to check for the causal direction of the variables of interest. An insignificant but slightly positive relationship between inequality and economic growth in the euro area was found. Countries with more inequality experienced on average fewer but longer growth spells. Further, only three out of 11 hypotheses regarding the transmission mechanism were confirmed by the data at hand.
info:eu-repo/semantics/publishedVersion

Variability in the relationship between tree leaf area (TLA) and selected stem measurements was examined in three Douglas-fir stands (Pseudotsuga menziesii (Mirb.) Franco, var. menziesii) that were less than 50 years-old, spaced to approximately 550 to 650 stems/ha, and differed in soil moisture and nutrients. Attention was given to the effect of mean annual ring width (MARW), cross-sectional area of the live bark (ALB - a surrogate measure of relative nutrient storage in the stem), and cross-sectional area of the most recent annual rings equal in number to the number of whorls in the live crown (ALC), on variability in the relationship between TLA and cross-sectional area of sapwood (ASW). At breast height, basal area, ASW, and cross-sectional area of sapwood plus live bark (ASWLB) were not linearly related to TLA, and linear regression equations using log transformed variables varied significantly between sites. Nonlinear regression equation for ASW at breast height was: TLA = 0.064ASẆ¹•³³ (I² = 0.856). Including D (the distance between breast height and the center of the live crown) in the nonlinear equation, did not significantly improve the regression. Tree leaf area prediction models using stem measures from the base of live crown (blc) had higher adjusted R² values than models using stem measures from breast height. At the blc, basal area, ASW, and ASWLB were linearly related to TLA (adjusted R² = 0.926, 0.908, and 0.934, respectively). Multiplying ASW by MARW did not improve the fit of the regression models. Multiplying ASW by ALB improved the linearity of the relationship of ASW at breast height to TLA. The best fitting TLA model overall used the product of ASW at blc and ALB at blc as the independent variable (adjusted R² = 0.967). The results indicate that research into the allometric relationship of TLA to stem measures should give consideration to more than hydraulic measures and include measures of bark function. At breast height and the blc, the independent variable ALC was linearly related to tree leaf area and had higher adjusted R² values than did ASW. In most trees the ALC stem measure was found to include a portion of heartwood area. The strong relationship between TLA and ALC suggests that a given transpiring leaf mass or area is related to a proportional amount of conducting stemwood and physical support stemwood. A quick alternative approach for estimating individual tree leaf area using photographs taken at fixed distance and angle from the target tree did not result in a reliable tree leaf area prediction technique. The difficulty of obtaining views of the tree crown which were not obstructed by adjacent tree crowns was the major obstacle. Using a fixed distance and camera angle was a problem because of variable tree heights. However, altering these fixed positions introduced additional variation into the tree leaf area estimation. Mean specific leaf area (SLA) varied significantly by site, needle age class, and crown position. Mean SLA per needle age class per branch can be predicted with 95% confidence and a 10% allowable error using six 10-needle samples.
Forestry, Faculty of
Graduate

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
As premências da sociedade contemporânea têm dependido gradativamente mais do uso de dispositivos optoeletrônicos como solução para o aperfeiçoamento de inúmeras aplicações diárias. Notadamente na última década, áreas como a de geração de energia elétrica com células solares inorgânicas ou a de computação com o advento de computadores quânticos baseados em fótons únicos têm acumulado muitos investimentos em pesquisa. Este trabalho visa estudar e definir os parâmetros necessários para a produção de pontos quânticos (QD, do inglês Quantum Dot) de semicondutores III-V com o objetivo de aplicá-los como material ativo para células solares de banda intermediária (IBSC, do inglês Intermediate Band Solar Cell) e para emissores de fótons únicos quando inseridos em nanofios (QD-in-NW, do inglês QD in Nanowire). Para a aplicação em IBSC, os pontos quânticos são produzidos auto organizadamente pelo modo Stranski-Krastanow. A estrutura de banda do IBSC requer um poço de potencial fundo o suficiente para gerar 3 absorções em paralelo de fótons com energias distintas (um proveniente da energia de gap do material da barreira, um da absorção banda-banda do poço de potencial e o terceiro da absorção intra-banda do poço na banda de condução). Os materiais escolhidos foram barreiras de AlxGa1-xAs e poço de InAs crescidos sobre um substrato de GaAs(100). Os resultados do crescimento dessa estrutura foram analisados por microscopia de força atômica (AFM, do inglês atomic force microscopy), microscopia eletrônica de varredura (MEV), microscopia eletrônica de transmissão (MET) e fotoluminescência (PL, do inglês photoluminescence). Para a aplicação em emissores de fótons únicos, os QDs (de InxGa1-xAs) são crescidos axialmente sobre nanofios de GaAs em substrato de GaAs(111)B. A técnica de crescimento escolhida neste caso foi o crescimento seletivo (SAG, do inglês selective area growth) que traz muitas vantagens com relação à qualidade cristalina e futuras litografias para fabricação do dispositivo. Tal técnica consiste na aplicação de uma máscara sobre o substrato com buracos nanométricos dentro dos quais a epitaxia ocorre exclusivamente. Os resultados de crescimento da estrutura foram analisados por MEV, MET, PL e espectroscopia de raios X por dispersão em energia (EDX, do inglês Energy-dispersive X-ray Spectroscopy). Em ambos os casos, o crescimento das estruturas finais foi otimizado. Foi possível obter correlações da influência de cada parâmetro de crescimento na morfologia, cristalinidade e composição das estruturas. No caso dos QDs para IBSC, o método usado de recobrimento por In-flush foi determinante para a melhoria da qualidade cristalina das camadas e da homogeneização da altura dos QDs. No caso da estrutura de QD-in-NW, primeiro precisou-se encontrar os parâmetros de crescimento dos nanofios para atingir uma razão de aspecto alta, e só posteriormente estudou-se as condições para que o InAs crescesse axialmente sobre o nanofio. As caracterizações, principalmente a ótica, de ambos os trabalhos indicam que as estruturas propostas foram produzidas.
In contemporary society the dependence on optoelectronic devices for countless daily applications has increased gradually. Particularly in the last decade fields such as energy generation through inorganic solar cells or quantum computation based in exchange of single photons has been heavily funded for their development. The aim of this thesis is defining the production parameters needed to fabricate quantum dots (QD) based on III-V semiconductors with planar geometry for intermediate band solar cell (IBSC) and with nanowire geometry (quantum dot in nanowire, QD-in-NW) for single photon emitter applications. For IBSC, the QDs are generated via self-assembly by Stranski-Krastanow mode. The IBSC s band structure requires a potential well deep enough to have 3 parallel photon absorption in different energy ranges (one is the barrier s energy gap, another is from the valence band to the intermediate band and the third one is from the intermediate band to the top of the barrier). The selected materials were AlxGa1-xAs as barriers, InAs as well, all grown on GaAs(100) substrate. The growth results were analysed by atomic force microscopy (AFM), scanning eléctron microscopy (SEM), transmission eléctron microscopy (TEM) and photoluminescence (PL). For the single photon emitters, the QDs (InxGa1-xAs) are grown axially over GaAs nanowires on a GaAs(111)B substrate. The chosen growth technique was the selective area growth (SAG) that brings many advantages in crystal quality and device lithography. This technique consists of applying a mask over the substrate with nanometric holes inside which the epitaxy occurs. The results were analysed by SEM, TEM, PL and energy dispersive X-ray spectroscopy (EDX). In both cases, the growth of the structures were optimized for better quality. The growth parameters could be correlated with the structure’s morfology, cristalinity and composition. For the IBSC, a capping method named In-flush was used to increase the crystal quality from the layers and the homogeneity from the QD s heights. For the QD-in-NW, firstly the nanowire s growth was optimized for higher aspect ratio and only then the growth of the InAs QD was optimized for axial growth over the nanowire. In both cases the optical measurements show that the proposed structures were grown successfully.

CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
A integração monolítica de um modulador com um guia de onda é de muito interesse para aplicação em comunicações ópticas pelo fato de que podemos diminuir as perdas por acoplamento óptico entre os dois dispositivos e usar moduladores curtos que operem em altas taxas de transmissão de dados. O crescimento epitaxial seletivo é uma das técnicas mais promissoras na atualidade para aplicação na integração monolítica de dispositivos semicondutores. Esta técnica permite controlar a espessura e a tensão das camadas crescidas seletivamente permitindo otimizar a integração e as características das estruturas dos dispositivos. A tese trata da implementação, do estudo e da aplicação do crescimento epitaxial seletivo por MOCVD de estruturas casadas e tensionadas de poços quânticos múltiplos de InGaAs/InAlAs para a fabricação de moduladores de amplitude baseados no efeito Stark e sua integração com guias de onda. O desempenho dos moduladores, baseados em estruturas de poços quânticos múltiplos de InGaAs/InAlAs que operam em 1,55 ym, é notavelmente melhorado quando é introduzida uma composição de 52% de Ga na liga e se tem um poço de ~100 A de espessura. Nesse caso, os moduladores possuem uma elevada figura de mérito e podem ser insensíveis à polarização. Nesse estudo foram crescidas várias amostras onde foi analisado o aumento na taxa de crescimento e a variação na composição das ligas de InGaAs e InAlAs em material bulk e em poços quânticos de InGaAs/InAlAs em função da geometria da máscara utilizada, i.e. diferentes larguras do dielétrico e largura da janela onde ocorre o crescimento fixo. Finalmente foram processados guias de onda cujas estruturas foram crescidas com a técnica de crescimento seletivo. Esses guias foram caracterizados por técnicas de campo próximo.
The monolithic integration of a modulator with a waveguide is a lot of interest for application in optical communications for the fact in that can decrease the losses for optical joining between the two devices and to use short modulators that operate in high rates of transmission data. The selective growth is at the present time, one the more promising technique for application in the monolithic integration of semiconductors device. This technique allows to control the thickness and the stress of the grown layers allowing to improve the integration and the characteristics of the devices structures. These thesis is about the implementation, study and application of the selectuve growth by MOCVD of both match and tensile structures of multi quantum wells of inGaAs/InAlAs for the production of the amplitude modulators based on the Stark effect and its integration with waveguide. The performance of the modulators based on structures of multi quantum wells of InGaAs/InAlAs operating in 1,55 um, is notably improved whena Ga composition of 52% is used and the thickness of a quantum well is near to ~100 A. In that case, the modulators have a high figured of merit and they can be insensitive to the polarization. In this study, several samples was grown and the growing rate increase was analyzed and the variation of the composition in InGaAs and InAlAs in bulk alloys and in quantum wells of InGaAs/InAlAs in function of the window where the growth is spent. Finally, waveguides were processed whose structures were grown with the technique of selective growth. Those guides were characterized by the near field technique.

Relationships between the culmination of basal area growth and degree of crown closure in loblolly pine (Pinus taeda L.) were investigated. A spacing trial established on the low Appalachian Piedmont and Atlantic Coastal Plain provided the data for the investigation. Test plots were planted at densities ranging from 303 to 2723 stems per acre, and at various rectangular and square spacings. Annual stem and crown measurements were used to derive the sought-after relationships. The age of basal area culmination was found to be inversely related to both planting density and site index. Crown closure was advanced on sites of relatively high quality, exhibiting an approximately linear increase with time from planting until the age of basal area culmination. The slope of this trend increased with planting density. The degree of crown closure at the age of basal area culmination was significantly higher on narrowly-spaced plots than it was on widely-spaced plots; however, it did not vary significantly with site index. Although crown closure is generally accelerated on high quality sites, the relatively early culmination of basal area growth on such sites offsets the increase - the net result being that crown closure at culmination age does not vary significantly with site differences. Crown closure indices can be used to determine whether or not a stand has reached the culmination of basal area growth; however, more readily available information on spacing and site index can be used to make the same prediction. The results of this study might be most useful to modelers of early stand dynamics in loblolly pine and other commercially important pines.
Master of Science

Mestrado em Economia Monetária e Financeira
Esta dissertação analisa a relação quadrática entre o rácio da dívida sobre o PIB e o crescimento económico, com o objectivo de encontrar um limite a partir do qual um aumento da dívida prejudique o crescimento. Ao observar 12 países europeus entre 1993 e 2017, encontrou-se evidência empírica que sugere a existência de tais limites quando o rácio toma valores próximos de 110%. Este número é maior do que aquele encontrado em trabalhos de investigação anteriores. Também foi analisado o efeito de crescimento do rácio da dívida sobre o PIB, que pode ser mais forte do que o efeito do rácio em si.
This dissertation studies the quadratic relationship between the debt-to-GDP ratio and GDP growth rate, and attempts to find threshold levels past which an increase in debt harms growth. Observing 12 European countries from 1993 to 2017, evidence was found supporting the existence of thresholds around the 110% debt-to-GDP ratio. These thresholds are considerably higher than those found in previous research. The growth rate of the debt-to-GDP ratio was also analyzed and found to have an impact on GDP growth which might be stronger than that of the ratio itself.
info:eu-repo/semantics/publishedVersion

The most commonly used equation to describe size at age in fishes is the von Bertalanffy equation (VBE), which assumes that growth rate is based on the balance of anabolic and catabolic processes: dW/dt = HW&\sp{lcub}\rm d{rcub}&-kW&\sp{lcub}\rm m{rcub}&. Anabolism, HW&\sp{lcub}\rm d{rcub}&, is considered proportional to gill surface area (A = rW&\sp{lcub}\rm d{rcub}&), and a "generalized" VBE (GVBE) has been previously determined: L&\sb{lcub}\rm t{rcub}& = L&\sb\infty&(1-exp(-KD(t-t&\sb{lcub}\rm O{rcub})))\sp{lcub}\rm 1/D{rcub}&, where D = b-bd and b is from W = qL&\sp{lcub}\rm b{rcub}&. The growth rate may be rewritten in terms of gill area, A, as dW/dt = kA/(A&\sb\infty&/W&\sb\infty\sp{lcub}\rm m{rcub}&)-kW&\sp{lcub}\rm m{rcub}&. Gill areas were examined for sandbar and tiger sharks. Values of the gill area coefficient, d, were fit to a modified Ford-Walford equation (OFW) and the gill area growth equation using length at age data for sandbar, tiger, dusky, blue, white, and shortfin mako sharks to calculate GVBE parameters. The adequacy of the GVBE is dependent on the data set. The OFW produced realistic results for seven data sets, but produced unrealistic L&\sb\infty& estimates for three other data sets. The gill area growth equation produced realistic results for five data sets, but not for two other data sets. A&\sb\infty&/W&\sb\infty& for the lamnid sharks are greater than for the carcharhinids, and within the carcharhinids, A&\sb\infty&/W&\sb\infty& for tiger, dusky and blue sharks are similar, but greater than for sandbar sharks. Growth in individual sandbar sharks was not correlated with individual gill areas. The results support the hypothesis that species- or population-specific dW/dt &\propto& A/W, and that decreasing A/W results in asymptotic growth. However, other factors may obscure the influence of individual variability in gill area on individual variability in growth rates.

Pour répondre aux défis matériaux relatifs à l’intégration des semiconducteurs III-V sur silicium, l’utilisation de nanostructures telles les boîtes quantiques et les nanofils s’avère une voie très prometteuse. Associée à la miniaturisation continue des dispositifs, elle devrait permettre l’émergence de nouveaux circuits opto et microélectroniques performants. Cela nécessite auparavant une maîtrise complète de la croissance et de la technologie des architectures tridimensionnelles à l’échelle nanométrique. Dans ce contexte, ce travail présente l’étude de la croissance localisée de semiconducteurs III-V par épitaxie par jets moléculaires (EJM) dans des motifs nanométriques. Nous discutons d’abord l’homoépitaxie localisée d’InAs et InP et établissons que les conditions de croissance ainsi que la largeur et l’orientation des ouvertures permettent de contrôler la forme des nano-cristaux obtenus. Nous démontrons ensuite la croissance sélective à basse température de GaSb sur substrat GaAs (001) fortement désaccordé en maille par EJM assistée d’un flux d’hydrogène atomique. Nous mettons en évidence l'impact de l’orientation des ouvertures, ainsi que le rôle du rapport de flux Sb/Ga sur la relaxation des nanostructures GaSb. Enfin, à partir de cette étude, nous démontrons comment ces nanofils GaSb peuvent être utilisés pour la croissance ultérieure de nanofils InAs horizontaux
The use of nanostructures such as quantum dots and nanowires is a very promising way of integration of III-V semiconductors on silicon, since it allows answering most of the associated material challenges. Together with the continuous trend in device scaling, it should lead to the development of new highly efficient opto- and microelectronic circuits. This appeals for a full mastering of the growth and processing of 3D architectures at the nanometer scale. Consequently, the present work aims at investigating the selective area growth (SAG) of III-V semiconductors by molecular beam epitaxy (MBE) in nanoscale patterns. Homoepitaxial SAG of InAs and InP are first reported in order to show that the growth conditions, the opening width and the stripe directions allow tailoring the nanocrystal shape. We then achieve the SAG of in-plane GaSb nanotemplates on a highly mismatched GaAs (001) substrate at low temperature by atomic hydrogen assisted MBE. We highlight the impact of the nano-stripe orientation as well as the role of the Sb/Ga flux ratio on the strain relaxation of GaSb. Finally, from this study, we demonstrate how these GaSb nanotemplates can be used for subsequent growth of in-plane InAs nanowires

Development over the past sixty years has created patterned growth and expansion outward from city centers, separating residences from commercial areas and employment centers. This separation of land uses has increased automobile dependency, which increases vehicle miles traveled and associated greenhouse gas emissions. California Senate Bill 375 mandates the development and implementation of a “Sustainable Communities Strategy” in order to plan regional land use and transportation in a coordinated fashion. In coordination with this effort, the Association of Monterey Bay Area Governments (AMBAG) is developing the Regional Implementation Plan for Smart Growth Development Strategies, which entails the identification of smart growth strategies that offer the greatest potential to reduce vehicle miles traveled and meet the 5% greenhouse gas emissions reduction target for the Monterey Bay Area. The major goal of this project was to assist AMBAG in determining the political feasibility of smart growth development strategies and identifying the most feasible strategies for the region. Political feasibility was determined by two factors: 1) support from the public/stakeholders, 2) “low-hanging fruit” potential, and one technical criterion: the potential to reduce vehicle miles traveled and the associated greenhouse gas emissions. The Regional Advisory Committee provided ten months of knowledge and expertise on stakeholder opinions v about strategies, barriers, circumstances for gaining stakeholder support, and resources for implementation. Additionally, survey results from planning directors the “low-hanging fruit” strategies. The quantified VMT/GHG reduction potential of smart growth strategies was another evaluation criteria and was used to inventory quantified reduction measures and their ranges of potential. The analysis identified seventeen strategies that met a set of thresholds for political feasibility. Based on these results, it is recommended that AMBAG consider these strategies in the development of their plan, by addressing the barriers to implementation, the conditions or circumstances for overcoming those barriers and gaining support from stakeholders, and developing the resources to assist jurisdictions with implementation.

Warm season grasses are increasingly being cultivated in North America for summer forage, soil conservation, and biomass production. In more northern environments, temperature and length of growing season have an overriding effect on the productivity of warm season grasses. There is limited information on the adaptability and production potential of warm season grasses in these short season areas. A study was conducted in south-western Quebec from 1993 to 1996 to evaluate the productivity of five species of warm season grasses. Phenological development, canopy leaf area development and architecture, radiation-use efficiency (RUE), yield and chemical composition were determined. In terms of phenology, there was a diversity of developmental patterns and the genotypes of greatest potential were characterised by early spring growth and late onset of dormancy in fall. Most of the genotypes that were early in spring growth were also early maturing and low yielding. Late maturing genotypes were generally late in spring growth, high yielding and generally of southern origin. Differences in developmental patterns were partly explained by differences in base temperatures for germination and growth, and growth rates. Seed osmoconditioning and/or matriconditioning alleviated effects of low temperatures on switchgrass seed germination and potential establishment. Maximum leaf area index ranged from 6.1 to 8 and the vertical leaf area distributions and light interception levels varied among genotypes. Average end of season biomass yields ranged from 8.5 to 14.4 Mg ha-1. Switchgrass rates of DM accumulation ranged from 175 to 191 kg ha-1 day-1 and RUE 0.89 to 1.1 g MJ-1 of incoming solar radiation. Moderate amounts of N fertilisation increased yield and quality of switchgrass, which could be harvested in a 2-cut system. NDF and ADF ranged from 77--88 and 46--57% respectively, and showed a rapid increase to a mid season plateau. Nitrogen concentrations declined curvilinearly wit

The thesis provides a deeper understanding of migration flows to high amenity areas using the example of migration to and from Cornwall. Cornwall is a remote, non-metropolitan county which has been experiencing very strong population growth since the 1970s almost solely due to in-migration. There are several aspects of the project that should contribute to an understanding of internal migration in England and Wales. First, a cohort analysis of migrants brings insights into the migration strategies of in-migrants and out-migrants throughout the period. Using the case of Cornwall allows the examination of migration patterns in a peripheral location where commuting opportunities are limited, and allows comparison with a more accessible rural area, Wiltshire. Secondly, through the creation of a new area type classification the project helps to explore the environmental dimension of migration. The typology is used to investigate the residential patterns of migrants and non-migrants and to test the hypothesis that environmental preferences are significant in the choice by in-migrants of where to live. Finally, The research investigates some pressing issues in Cornwall, issues which are relevant also for other non-metropolitan areas, such as the shortage of affordable housing, the detrimental impact of tourism and poor economic development, and their links with migration. The research focuses especially on labour market problems and housing need, due to their policy relevance. Comparisons between the migrant and non-migrant populations provide the basis for estimating the impacts of migration on the restructuring of labour and housing markets in Cornwall.

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第19755号
農博第2151号
新制||農||1038(附属図書館)
学位論文||H28||N4971(農学部図書室)
32791
京都大学大学院農学研究科農学専攻
(主査)教授 白岩 立彦, 教授 奥本 裕, 教授 稲村 達也
学位規則第4条第1項該当

A dimensionally compatible system of equations for stand basal area, volume, and basal area and volume growth was derived using dimensional analysis. These equations are analytically and numerically consistent with dimensionally compatible individual tree volume and taper equations and share parameters with them. Parameters for the system can be estimated by fitting individual tree taper and volume equations or by fitting stand level basal area and volume equations. In either case the parameters are nearly identical. Therefore, parameters for the system can be estimated at the tree or stand level without changing the results. Data from a thinning study in loblolly pine (Pinus taeda L.) plantations established on cutover site-prepared lands were used to estimate the parameters. However, the developed system of equations is general and can be applied to other tree species in other locales.
Ph. D.

By the mid-1970s, Tanzania had the biggest co-operative movement in Africa and the oldest in East Africa. Despite such achievement, for decades, the literature on Tanzania’s small-scale coffee and cotton cultivation and marketing co-operatives has suffered from a dearth of substantive historical accounts. The available literature is fragmented along various academic disciplines, mostly political science and sociology. In addition, there is no single substantive secondary historical study specifically dedicated to the co-operative movement since the inception in 1932. The neglect is more critical given the current renaissance in Africa and increasing international interest in the co-operative movement at either national or local levels. This thesis seeks to fill this gap by utilising primary sources from the Co-operative College archive in Manchester and Tanzania National Archive (TNA) to examine and evaluate the coffee and cotton marketing co-operatives during the 1932 to 1982 period. The study further explores the interlocking forces and policies that led to its growth and development. The development is also examined against the changing political and ideological influences during the interwar, and post-war to independence periods. This thesis is structured under three cases, two of which are coffee marketing co-operatives, the Kilimanjaro Native Co-operative Union (KNCU) and Bukoba Co-operative Union (BCU) in Kagera; and the cotton apex marketing co-operative in the WCGA, the Victoria Federation of Co-operative Unions (VFCUS) which was formed in 1955. Study findings show that the time gap in the formation of the mentioned co-operatives were due to the colonial authority neglecting its own co-operative development policy. The evidence shows that, the KNCU which was formed in 1933 and BCU in 1950 were both established at the behest of the British colonial government in a move to control the coffee industry. Importantly, the study examines the power relations involved and the government interventions in the process and the extent to which the co-operatives were promoted and controlled by the government through the co-operative and agricultural marketing policies and legislations. This was particularly provided under Section 36 of the 1932 co-operative legislation and was further reinforced by three policies, the 1934 Chagga Rule, the 1937 Native (control and marketing) Ordinance and the Defence Ordinance, Orders of 1939 and 1940; and the African Agricultural Products (Control and Marketing) Ordinance, 1949. The post-colonial authority perpetuated the colonial policies in promoting co-operatives and the control of agricultural export revenues provided under the 1962 by the National Agricultural Products Board (Control and Marketing) Act by intensifying the intervention, effectively strangling and restructuring them to provide for effective control. Again, there was an increased politisation of the movement’s function as they became an integral part of the propagation of the socialist/ujamaa ideology and the national development plan as the 1976 villagisation policy. This study is of the view that the colonial and post-colonial authorities intervened in the formation of co-operatives given the fact that they were economically strategically vital. During the phases covered in this thesis, the established legislations reinforced the government’s control over the co-operative movement and the producers; and granted themselves a monopoly over the handling and export of small-scale produced coffee and cotton through the control of marketing boards by appointing co-operatives as crop handling agents. Thus, the co-operative movement never attained autonomous status as it became part of the government machinery in extracting resources and exploiting small-scale growers.

The cornerstones of Oregon's 1973 Senate Bill 100 are the preservation of farm, forest, and other resource lands and the containment of urban development within urban growth boundaries (UCB). The UCB is a boundary around each incorporated city containing enough land to meet projected needs until the year 2000. The Land Conservation and Development Commission (LCDC), charged with adopting and implementing state planning policy, sought to keep UGBs small enough to contain urban sprawl. To avoid the potential effects of land price inflation, LCDC allowed UGBs to include more land supply than the forecasted demand. The Portland-Metropolitan region was allowed to have a 15.3-percent surplus. Policy makers are unsure what effect UGBs have on housing costs. The common belief is that by restricting the amount of land available for residential construction the market drives prices up. Contrasting opinions suggest that by substituting low-density with high-density development, per-unit construction costs are lower, thus reducing the costs of owning a home. Efforts to dispel some of the mystery about the relationship between UGBs and housing prices are needed. The objective of this research is to provide empirical evidence of the relationship between the Portland-Metropolitan area's UGB and housing prices. The study uses a hedonic model to conduct a time-series analysis for the years 1978 to 1990 for Washington County. This study found no relationship between housing price and the imposition of the UGB. In fact, the rate of increase in price for single-family housing after UGB implementation was found to be much less than before. Proximity as measured by distance of sale to the UGB was the only variable that was associated with a higher rate of increase in housing prices. All of these results, with the exception of those related to proximity, were unexpected but may be explained by several factors: imposition of the Metropolitan Housing Rule in 1981, a severe recession during the 1980s, and excess land supply. These influences do not support a conclusion that UGBs lead to an increase in housing prices, at least prior to 1990, when the UGB did not constrain the supply of land.

Field experiments were conducted in Kentucky and Louisiana in 2008 and 2009 (split-plot in a randomized complete block design with four replications) to investigate it is possible to simulate with manual defoliation the effect of soybean rust (SBR) (Phakopsora pachyrhizi Syd. and P. Syd) injury on a healthy soybean [Glycine max, (L.) Merr.] canopy, understand how defoliation affects the growth dynamics and canopy light interception, and if defoliation affectsleaf senescence and nitrogen remobilization during the seed-filling period. Two manual defoliation treatments based on changes in effective leaf area index (ELAI) (calculated as the reduction in leaf area equivalent to SBR-induced premature leaf abscission, loss in green leaf area, and reduction in photosynthetic capacity of diseased leaves) in infected canopies in Brazil were used to simulate SBR infection at growth stage R2 (full flowering) and R5 (beginning of seed-fill). Both defoliation treatments reduced yield in all experiments and the reduction was larger for the treatments at growth stage R2. The yield losses were equivalent to that observed in infected soybean canopies in Brazil. This suggests that a system of manual defoliation to simulate changes in effective leaf area duration shows promise as a tool to simulate the impact of SBR on soybean yield. The radiation use efficiency and crop growth rate from growth stage R2 to R5 were not influenced by defoliation. Defoliation started at growth stage R2 reduced seed number per unit area, while defoliation started at growth stage R5 reduced seed size due to shortening the seed-fill duration and a lower seed growth rate. There is no evidence that manual defoliation affected leaf senescence or nitrogen redistribution to the seed. This study found that the reduction of light interception by SBR was the main reason for the reductions in soybean growth and yield.

The objective of this project is to establish a new technology to grow high quality GaN based material by nano selective area growth (NSAG). The motivation is to overcome the limit of the conventional growth method, which yield a high density of dislocation in the epitaxial layer. A low dislocation density in the epitaxial layer is crucial for high performance and high efficiency devices. This project focuses on growth and material characterization of GaN based nanostructures (nanodots and nanostripes) grown using the NSAG method that we developed. NSAG, with a precise control of diameter and position of nanostructures opens the door to new applications such as: 1) single photon source, 2) photonic crystal, 3) coalescence of high quality GaN template, and 4) novel nanodevices.

Data from Nelder spacing trials for a limited range of ages from 1 to 7, were used to model the growth of basal area and mean top height of Eucalyptus grandis in Zimbabwe. Two projection functions, the log reciprocal and Hossfeld were tested on data arranged as non overlapping (T₁-T₂, T₂-T₃, ...... Tn-₁-Tn) and overlapping (T₁-T₂, T₁-T₃, T₁-Tn, T₂-T₃, T₂-Tn, etc). The log reciprocal performed poorly on both overlapping and non overlapping mean top height (h 100) data. The Hossfeld function fit to overlapping and non overlapping h100 data did not appear to be very different, but overall the fit to overlapping data was slightly superior. The log reciprocal fitted both overlapping and non overlapping basal area (G) data better than it did with h100 data, but the Hossfeld still proved superior with the overlapping data. The functions were first run without the initial stocking variable and although its inclusion caused small improvements in the fitting. The small improvements that were used to eliminate some of the functions were quite important when the h100 and G were converted to volume/ha in the stand volume equation. The Hossfeld function, with the initial stocking included, fitted to overlapping data for both h100 and G, was the preferred choice of projection equation.

This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.
Bachelors
Sciences
Political Science

Doutoramento em Nanociências e Nanotecnologia
The present work is aimed to provide description of experimental part of graphene and two-dimensional structures. State-of-the-art techniques employing chemical vapor deposition (CVD) were used to deposit graphene and two-dimensional structures for their multidisciplinary applications including nano-electronics and semi-conducting industries. All the problems, suggestions and other important issues related to the growth and parameterizing the optimum condition for strictly monolayer to few layers have been briefly discussed. This may give double benefits such as realizing 2D electronic devices with high carrier motilities and understanding the behaviour of these 2D materials upon small ion intercalation. The as synthesized graphene grown on copper (Cu) substrate showed the ideal Raman spectrum with least defect concentration. The presence of very small D peaks confirmed the high quality of graphene crystals with strictly monolayer to few layers. Moreover, High Resolution X-rays Spectroscopy (HR-XPS) analysis showed the high quality graphene with C 1s in sp2 configuration (with binding energy at ~284.8 eV). The absence of other components resembled the purity of graphene and again reconfirmed the good quality of synthesized graphene. The Raman image mapping, demonstrated the full coverage of large area graphene on copper substrate. Additionally, the High Resolution Transmission Electron Microscopy (HRTEM) results reconfirmed that the high crystalline nature with two-type of rotational planes, which may attributed to the presence of wrinkles formed during the transfer of graphene sheet on TEM grids. This thesis is also devoted to the heteroatom doping in order to tune the electronic properties of graphene. Ammonia (NH3) was used herein to provide nitrogen (N) as a source for foreign atom for the doping of pure graphene. Here again, efforts were made to discuss all the problems, suggestions and other important issues related to growth and parameterizing the optimum conditions for in-situ ammonia doping of graphene on Cu. The substrate (thickness of films) playing role in the defect creations was also discussed. Raman results showed the enhanced D and D’ peaks, which confirmed the doping of graphene by NH3. HRXPS showed the C 1s core level centred at a BE of 284.5 eV, ascribed to C sp2 can be co-related with the good quality of C. Thus, in context with the XPS, the graphene grown on 20 µm Cu substrate showed the better nitrogen intercalation in the graphene sheets under the same growing conditions. Two components (substitutional at BE of 401.7 eV and pyridinic at BE of 398.5 eV) were clearly distinguished in the respective N 1s core level. The doping with substitutional type of configuration, involves three nitrogen valence electron forming three σ– bonds, one electron filling the π–states, and the fifth electron entering the π*–states of the conduction band, and altogether provide a strong doping effect. The presented work also reported a study demonstrating an in-situ method for the quantitative characterization of nanoscale electrostatic properties of as-grown multilayer-graphene (MLG) sheets on nickel (Ni) by combining atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). Large area epitaxial MLG sheets were grown on Ni by using CVD technique. The high crystalline nature of MLG sheets on Ni was confirmed by Raman spectroscopy with the FWHM value as low as ~20 cm-1 for G peak. We performed the charge injection (and subsequent charge diffusion over time) on the as synthesized graphene on Ni. The results unveiled that: (i) MLG surface can be either positively or negatively charged through injection process using Pt coated Si-based AFM probes; (ii) the charges can be accumulated and eventually reached to saturated concentrations of (+4.45±0.1) μC/m2 and (−1.3±0.1) μC/m2 , respectively; and (iii) the charge diffusion coefficients on graphene surface were measured to be (1.50±0.05) × 10−16 m2 /s and (0.64±0.05) × 10−16 m2 /s for the positive and the negative charges, respectively. The concerned experiment related to the discovery of charge injection in MLG may pave the way for designing a new class of energy harvesting devices. In addition to this, study also demonstrated a technique for nano-patterning/charge lithography of surface charges by contact electrification, which could be a promising application to create charged nanostructures for next generation graphene based nano-electronic devices. A brief description on the quality of transferred substrate has also been noted. Various substrates such as SiO2/Si and Au substrate have been used. A relative quality comparison between before and after transfer of graphene has been critically described. Results from HRXPS show the iron monolayer interaction with graphene. Lastly, this research also showed the major parameterizing and synthesizing steps, and the work flow for the high quality TMDs materials (such as MoS2) by modifying the current CVD equipment. A thorough review of the fundamental properties as well as methods of synthesis, properties and problems related to the growth of 2D materials was also highlighted. The effect of pressure and other conditions for the growth of high quality were fully described. This study found 50mbar as an optimum pressure for the growth of large area MoS2 having a direct bandgap of 1.6eV. Micro-Raman results clearly showed distinguish E1 2g and A1 g peaks and HRXPS re-confirmed its high quality by the different Mo and S core-level peaks. Additionally, employing Focused ion beam equipped with SEM (scanning electron microscopy) technique (FIB), the present study prepared platinum (Pt) electrodes required for the electrical measurements. The result showed: (i) the ohmic and semi-conducting behavior of the crystals; (ii) the importance of high-quality singlelayer (SL) MoS2 in the semi-conducting industries; and (iii) the potential of high quality SL MoS2 for replacing graphene in near future.
O presente trabalho, tem com objetivo promover a descrição da parte experimental da síntese de grafeno e de estruturas bidimensionais (2D). Foram usadas as técnicas já existentes, que aplicam deposição química na fase de vapor (CVD), para a síntese de grafeno e estruturas bidimensionais com aplicações multidisciplinares, como indústrias de nano-eletrónicos e de semicondutores. Todos os problemas, sugestões e questões importantes relacionados com o crescimento e parametrização da condição ótima para formação de estritamente monocamadas a pequenas camadas foram brevemente discutidas. Isto pode trazer benefícios duplos como a produção de dispositivos eletrónicos 2D com altas motilidades de transporte e o entendimento do comportamento dos materiais 2D sujeitos a intercalação iónica. Os grafenos sintetizados no substrato cobre (Cu) apresentaram um espectro ideal de Raman com uma concentração de defeitos menor. A presença de pequenos picos D confirmou a elevada qualidade dos cristais de grafeno com estritamente monocamadas a pequenas cadeias. Além disso, a espectroscopia de Raios-X de alta resolução (HR-XPS) mostrou o grafeno de elevada qualidade com C 1s em configuração sp2 (com energia de ligação a ~284.8 eV). A ausência de outros componentes reforça a pureza e a qualidade do grafeno sintetizado. As imagens de mapping Raman demonstraram a cobertura total do grafeno de elevada área no substrato cobre. Adicionalmente, os resultados de microscopia de transmissão eletrónica de alta resolução (HRTEM) confirmaram a elevada natureza cristalina com dois tipos de planos rotacionais que podem ser atribuídos à presença de rugas durante a transferência de folhas de grafeno nas grelhas de TEM. Esta tese dedica-se também à dopagem heteroatómica do grafeno com o objetivo de alterar as suas propriedades eletrónicas. A amónia (NH3) foi usada como fonte de azoto (N) como átomo externo para a dopagem do grafeno puro. Mais uma vez, foram feitos esforços para discutir todos os problemas, sugestões e outras questões importantes relacionadas com o crescimento e parametrização das condições ótimas para a dopagem in-situ de amónia do grafeno no cobre. O papel do substrato (espessura do filme) na criação de defeitos foi também discutida. Os resultados de Raman mostram o aumento dos picos D e D’, o que confirma a dopagem do grafeno por NH3. Os dados de HRXPS mostraram o pico C 1s centrado a uma energia de ligação (BE) de 284.5 eV, atribuído ao C sp2 que pode ser correlacionado com a boa qualidade do C. Então, de acordo com o XPS, o grafeno que cresceu no substrato Cu 20 µm apresentou uma melhor intercalação do azoto nas folhas de grafeno sob as mesmas condições de crescimento. As duas componentes (substitucional a BE de 401.7 eV e piridínica de 398.5 eV) foram claramente distinguidas no respetivo pico N 1s. A dopagem com o tipo de configuração substitucional envolve três eletrões de valência do nitrogénio formando três ligações σ, um eletrão a preencher os estados π e o quinto eletrão no estado π* da banda de condução que conduzem, no total, a um forte efeito de doping. O presente trabalho também reporta um método in-situ para a caraterização quantitativa das propriedades eletrostáticas na escala nano das folhas de grafeno multicamada (MLG) crescidas no níquel (Ni) por combinação de dados de microscopia de força atómica (AFM) e microscopia de força atómica Kelvin (KPFM). Folhas MLG de larga área epitaxial cresceram no Ni usando a técnica CVD. A elevada natureza cristalina das folhas MLG no níquel foi confirmada por espectroscopia Raman com valor de FWHM tão baixo como ~20 cm-1 para o pico G. Foi feita a injeção de carga (e subsequente difusão de carga com o tempo) no recém sintetizado grafeno no Ni. Os resultados revelaram que : (i) a superfície MLG pode ser carregada quer positivamente quer negativamente pelo processo de injeção usando sondas de Si revestidas de Pt; (ii) as cargas podem ser acumuladas e eventualmente atingir concentrações de saturação de (+4.45±0.1) μC/m2 e (−1.3±0.1) μC/m2 , respetivamente; e (iii) os coeficientes de difusão de carga na superfície medidos foram de (1.50±0.05) × 10−16 m2 /s e (0.64±0.05) × 10−16 m2 /s para as cargas positivas e negativas, respetivamente. As experiências relacionadas com a descoberta de injeção de carga no MLG podem conduzir a uma maneira de desenhar uma nova classe de dispositivos de recolha de energia. Além disso, este estudo também demonstra uma técnica para nano-modelação/litografia de carga das superfícies de carga por eletrificação do contacto, que pode vir a ser uma aplicação promissora para criar nanoestruturas carregadas para a próxima geração de dispositivos nanoeletrónicos baseados em grafeno. Uma breve descrição da qualidade dos substratos transferidos foi também explorada. Foram usados vários substratos, como SiO2/Si e Au. Uma comparação qualitativa da qualidade entre a transferência do grafeno antes e depois foi criticamente descrita. Os resultados de HRXPS mostram a interação da camada de ferro com o grafeno. Por fim, esta pesquisa também mostrou as principais etapas de parametrização e síntese, e o fluxo de trabalho para materiais de elevada qualidade TMDs (como MoS2), por modificação do actual aparelho de CVD. Uma revisão completa das propriedades fundamentais, assim como do método de síntese, propriedades e problemas relacionados com o crescimento de materiais 2D foram também salientados. O efeito da pressão e outras condições para o crescimento de elevada qualidade foram completamente descritos. Este estudo indica que a pressão ótima para o crescimento de uma larga área MoS2 com uma bandgap direta de 1.6 eV é de 50 mbar. Os resultados de micro-Raman mostram claramente a distinção de picos E1 2g e A1 g picos e os dados de HR-XPS reconfirmam a sua elevada qualidade através de diferentes picos de nível interno de Mo and S. Além disso, através do uso da técnica microscopia eletrónica de varrimento (SEM) com feixe de iões focalizados (FIB), foram preparados elétrodos de platina necessários para medidas elétricas. O resultado mostrou: (i) o comportamento óhmico e semi-condutor dos cristais; (ii) a importância das monocamadas de elevada qualidade (SL) MoS2 nas indústrias de semi-condutores e (iii) o potencial das SL MoS2 de elevada qualidade para substituir o grafeno num futuro próximo.

This study used two modelling approaches to predict future urban landscape for the Baltimore-Washington metropolitan areas. In the first approach, we implemented traditional SLEUTH urban simulation model by using publicly available and locally-developed land cover and transportation data. Historical land cover data from 1996, 2001, 2006, and 2011 were used to calibrate SLEUTH model and predict urban growth from 2011 to 2070. SLEUTH model achieved 94.9% of overall accuracy for a validation year of 2014. For the second modelling approach, we predicted future county-level population (e.g., 2050) using historical population data and time-series forecasting. We then used future population projection of 2050, aided by strong population-imperviousness statistical relationship (R2, 0.78-0.86), to predict total impervious surface area for each county. These population-predicted total impervious surface areas were compared to SLEUTH model output, at the county-aggregated spatial scale. For most counties, SLEUTH generated substantially higher number of impervious pixels. An annual urban growth rate of 6.24% for SLEUTH model was much higher than the population-based approach (1.33%), suggesting a large discrepancy between these two modelling approaches. The SLEUTH simulation model, although achieved high accuracy for 2014 validation, may have over-predicted urban growth for our study area. For population-predicted impervious surface area, we further developed a lookup table approach to integrate SLEUTH out and generated spatially explicit urban map for 2050. This lookup table approach has high potential to integrate population-predicted and SLEUTH-predicted urban landscape, especially when future population can be predicted with reasonable accuracy.
Master of Science

This study assesses the effects of a changing climate and population growth on water resources by modeling groundwater supplies in the Tucson Active Management Area. The finite-difference flow model, Modflow, is used to incorporate agricultural, municipal, and industrial well pumping along with natural and artificial recharge. This study expands on a Modflow model created by the Arizona Department of Water Resources to determine the impacts from limited water supplies and increased demand (Mason and Bota, 2006). Groundwater conditions and pumping in the Upper Santa Cruz and Avra Valley sub-basins are modeled starting in the year 1940 and continue to 2009. The model predicts pumping and recharge for the period of 2010 to 2050. During this projection period, nine scenarios based on various climate and population conditions are evaluated. Climate impacts are reflected in the amount of recharge entering the groundwater system. Local and regional climate conditions are incorporated since a large portion of the Tucson water supply is provided by the Colorado River water delivered along the Central Arizona Project (CAP). A decrease of 10% to the mean natural flow in the Colorado River over the next 50 years is used to predict Colorado River flows and shortages. Additionally, a 20% streamflow reduction case and two scenarios that evaluate the local and regional shortages individually are presented. Operational rules for the deliveries of the CAP water during shortage conditions are utilized to represent the system. The percentage of population growth is varied around the current case, which is extrapolated from data provided by the Arizona Department of Water Resources. Water demand is based upon the initial population, annual population growth, and gallons per capita day, which is a measurement of water use per person. The three population scenarios are limited growth, current case, and high growth. Results indicate groundwater depletion conditions are the worst during the high growth/shortage scenarios and best for the limited growth scenario. The change in storage of the aquifer is greatly driven by the pumping, which is dependent on population. For the shortage condition, the decline in natural recharge has a much larger effect on the change in water storage compared to the artificial recharge reductions due to shortages of CAP water.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2001.
Includes bibliographical references (p. 85-86).
This paper explores housing development in the Greater Seattle area in the context of the Washington State Growth Management Act. To establish an accurate picture of the workings of the Greater Seattle housing market, recent trends in regional employment growth, housing production, and home price movements are analyzed. Because the GMA imposes restrictions on development at portions of the region's urban/rural fringe, close attention is paid to the probable effects of constricting the region's supply of developable land, and to identification of development costs associated with denser housing typologies. Because the GMA envisions a network of Greater Seattle "Urban Centers" having high employment and household densities together with good access to roads, high levels of infrastructure and community resources, and good access to mass transit, two specific urban centers are reviewed: the Uptown Queen Anne Urban Center near downtown Seattle, and the Downtown Redmond Urban Center in Seattle's eastern suburbs.
by Kirk Nyland.
S.M.

Bibliography: leaves 199-209.
This study is an exploratory one of growth monitoring in a rural African village, Thornhill. Growth monitoring is a primary health care approach to prevent child malnutrition in under-developed areas promoted by a variety of development agencies, particularly UNICEF, as a part of the "child survival revolution." It involves weighing children regularly and plotting their weights on a growth chart retained by the child's mother. Growth charts provide a visual display of a child's growth to allow health workers and mothers to identify early signs of growth faltering in order to facilitate ameliorative action (usually food supplementation or nutrition education) to prevent malnutrition. It also aims to facilitate the active participation of mothers in ensuring their child's continual good growth. The history of growth monitoring and its use in the South African context is discussed. The underlying rationale and component processes needed to implement it effectively are identified in a review of process evaluation studies of growth monitoring. Thornhill is an impoverished African rural area in the Ciskei in which malnutrition is a serious health problem and growth monitoring has been systematically implemented. However, although the health service had a demonstrated capacity for successful health interventions it had been unable to improve nutritional status. Background information and previous research in the area is presented. The study aimed to explore why growth monitoring had failed to improve nutritional status in Thornhill by investigating the way in which the component objectives of growth monitoring in terms of making growth visible, facilitating nutrition intervention and facilitating mothers' participation in their children's care were perceived by mothers and health workers.

The Houston-Galveston-Brazoria Consolidated Metropolitan Statistical Area (Houston CMSA) has experienced rapid population growth during the past decades and is the only major US metropolitan area with no zoning regulations. We use SLEUTH, a spatially explicit cellular automata model, to simulate future (2002-2030) urban growth in the Houston metropolitan area, one of the fastest growing metropolises in the United States during the past decades. The model is calibrated with historical data for the period 1974-2002 that are extracted from a time series of satellite images. The dataset consists of four historical urban extents (1974, 1984, 1992, 2002), two land use layers (1992, 2002), five transportation layers (1974, 1984, 1990, 2002, 2025), slope layer, hillshade layer, and excluded layer. Future growth patterns are predicted based on growth coefficients derived during the calibration phase. After calibrating the model successfully, the spatial pattern of urban growth of the Houston CMSA for the period from 2002 to 2030 is predicted. Within SLEUTH, growth in the Houston CMSA is predominately "organic" with most growth occurring along the urban/rural fringe. Projected increases in urban area from 2002 to 2030 parallel projected increases in population growth within the Houston CMSA. We design three specific scenarios to simulate the spatial consequences of urban growth under different environmental conditions. The first scenario is to simulate the unmanaged growth with no restrictions. The second scenario is to project the moderate growth trend by taking into consideration environmental protection, specifically for agricultural areas, forests and wetlands. The last scenario is to simulate the managed growth with maximum environmental protection. Adjusting the level of protection for different land cover types was found to markedly affect the land use changes in the Houston CMSA. Without any protection on resource lands, Houston CMSA is estimated to lose 2,000 km2 of forest land by 2030, about 600 km2 of agricultural land, and approximately 400 km2 of wetland. Approximately half of all resource land could be saved by the third scenario, managed growth with maximum protection.