Um dos principais fatores limitantes da produção de algodão é a ocorrência de doenças e, entre os patógenos mais importantes estão às bactérias, que causam danos significativos à cultura. A doença conhecida como mancha angular, causada pela bactéria Xanthomonas axonopodis pv. malvacearum (Xam), é uma doença grave, que tem gerado grande preocupação dos produtores. Porém, muitos cultivares com boas características agronômicas apresentam suscetibilidade ao patógeno e, poucos são aqueles que apresentam resistência à doença. O controle da mancha angular é realizado basicamente com uso de resistência genética ao patógeno. Uma das principais fontes de inóculo para esta bactéria é a semente infectada. Este trabalho objetivou o desenvolvimento de um meio semi-seletivo para o isolamento de Xam em sementes de algodão, visando a utilização em análises de rotina em laboratórios de patologia de sementes. O meio de cultura semi-seletivo possuí a seguinte constituição: 3 g de extrato de carne; 5 g de peptona; 10 g de amido solúvel; 10 mL de Tween 80; 0,25 g de cloreto de cálcio; 150 µL de solução de cristal violeta a 1%; 50 mg de cefalexina; 10 mg de clorothalonil; 10 mg de tiofanato metílico e água destilada por 1000 mL. Este meio de cultura possui baixa repressividade a Xam e permite isolar este patógeno de sementes de algodão. / One of the main limiting factors of the cotton production is the occurrence of diseases. The bacteria are among the most important pathogens causing significant losses in the production. Cotton bacterial blight is caused by the bacterium Xanthomonas axonopodis pv. malvacearum (Xam). Is a serious disease that affects cotton and has worried world producers. The main source of inoculum for this bacterium is the infected seed. This work had as objective the development of a semi-selective medium to detect Xanthomonas axonopodis pv malvacearum in cotton seeds for routine tests in seed pathology laboratories. By fungitoxicity tests, basead on qualitative and quantitative antibiograms, it was idealized a semi-selective medium with the folloing composition: peptone (5.0 g/L); agar (15.0 g/L); meat extract (3.0 g); starch (10.0 g/L); violet crystal (150.0 µL violet crystal solution at 1%); water (1,000 mL); CaCl2 (0.25 g); Tween 80 (10.0 mL/L). This medium has small effect on Xam and allows to isolate cotton seeds pathogens.

Neste trabalho primeiramente estudamos os efeitos na propagação de ondas de Alfvén em plasmas empoeirados encontrados em inúmeros ambientes astrofísicos. A relação de dispersão da onda é modificada apresentando novos mecanismos de amortecimento. Há na literatura dados observacionais que indicam a existência de condições para crescimento de partículas de poeira na base da atmosfera de estrelas gigantes e supergigantes frias. Construímos um modelo de perda de massa para essas estrelas no qual mostramos que um fluxo de ondas de Alfvén, amortecido pela presença de poeira, pode contribuir para a geração de um vento de baixa velocidade e alta taxa de perda de massa, de acordo com as observações. Já no caso de estrelas quentes, mostramos como é possível obter as condições ideais para formação e crescimento destas partículas em um modelo de colisão de ventos em sistemas binários. A partir deste modelo, é possível explicar as altas emissões em raios-X observadas, além do crescimento de grãos no pós-choque. Aplicando a idéia ao sistema binário de eta Carinae, o modelo permite a determinação dos parâmetros orbitais do sistema. A poeira contida nos ventos estelares é então ejetada para o meio interestelar. Através de um cálculo semi-empírico determinamos a importância de cada intervalo de massa estelar, em cada etapa evolutiva, no retorno de material sólido ao MI. Em regiões de formação estelar investigamos como as ondas de Alfvén, amortecidas pela presença de poeira, influenciam a estabilidade de nuvens moleculares. Em oposição às teorias encontradas na literatura, mostramos que uma nuvem molecular anã, suportada apenas por pressão magnética, não pode ser dinamicamente estável. / In this work, we firstly discuss the propagation of Alfvén waves in dusty plasmas found in several astrophysical environments. The wave dispersion relation is modified giving rise to new damping mechanisms. There are in the literature observational data indicating the presence of dust near the surface of cool giant and supergiant stars. We developed a stellar mass loss model where we show that a flux of Alfvén waves, damped by the dust presence,can generate a low velocity and high mass loss rate wind, in agreement with the observations. In the case of hot stars we show how it is possible to obtain the special conditions for dust growth in a wind collision model of massive binary systems. For this model it is possible to explain both, the high X-rays emissions and dust growth at the post-shock phase. Applying the idea to the $eta$ Carinae binary system, the model allows the determination of the system orbital and the stellar wind parameters. The stellar wind´s dust is then ejected to the interstellar medium. In a semi-empirical calculation we showed the importance of each stellar mass, at each evolutionary phase, on the dust feedback of the ISM. For star formation regions, we investigate the role of Alfvén waves, damped by the dust presence, on the stability of the molecular clouds. In spite of the works found in the literature, we showed that a dwarf molecular cloud, magnetically supported only, is unstable.

Arthrosphira (Spirulina) platensis apresenta substâncias de interesse nas indústrias alimentícia, farmacêutica e cosmética. A produção industrial envolve uma quantidade muito grande de água e sua viabilidade deve contemplar o reuso do meio, visando uma diminuição de custos com nutrientes, bem como da poluição ambiental, tornando-se assim um processo sustentável. O presente trabalho teve como objetivo principal a avaliação do reaproveitamento do meio no cultivo de A. platensis usando tratamentos físico-químicos de floculação e adsorção. Para tanto, tal cianobactéria foi cultivada em fotobiorreator (FBR) tubular em processos de batelada alimentada e contínuo em intensidade luminosa de 120 µmol fótons m-2 s-1, sob controle de pH. Foram desenvolvidas técnicas de tratamento de meio de cultivo proveniente de processo descontínuo alimentado de A. platensis para a remoção de matéria orgânica (MO) e pigmentos (60 - 96 %), permitindo assim seu reuso em novos cultivos. A. platensis foi cultivada nos meios tratados utilizando frascos Erlenmeyer, com avaliação de parâmetros como concentração celular máxima (Xm), conteúdo de clorofila-a (Chl) e conteúdo de proteína na biomassa seca (PTN). No processo simultâneo de floculação e adsorção com carvão ativado em pó (CAP), foram testados dois agentes floculantes, cloreto férrico (F) e sulfato férrico (S) bem como diferentes tempos de contato. No processo simultâneo de floculação com F e adsorção com CAP, as condições ótimas foram: CAP = 24,4 mg L-1 e F = 20,3 mg L-1durante 30,4 min de tempo de contato; com obtenção de: Xm = 4893 ± 33 mg L-1, Chl = 24,3 ± 0,1 mg g-1, PTN = 36,1 ± 0,6 %. As condições ótimas de tratamento simultâneo de floculação com S e adsorção com CAP foram: CAP = 40,0 mg L-1 e S = 32,8 mg L-1 durante 36,1 min de tempo de contato, com obtenção de: Xm = 4863 ± 64 mg L-1, Chl = 24,5 ± 0,6 mg g-1, PTN = 60,1 ± 0,6 %. No processo sequencial de floculação com F seguido de adsorção com carvão ativado granulado (CAG), as condições ótimas foram atingidas com: CAG = 108,4 g e F = 10,0 mg L-1 durante 30,8 min de tempo de residência; obtendo-se: Xm = 3140 ± 77 mg L-1, Chl = 35,4 ± 0,2 mg g-1, PTN = 44,9 ± 0,0 %. Adicionalmente, os meios tratados nessas condições ótimas de cada tratamento, também foram testados em FBR tubulares, atingindo valores de Xm, Chl e PTN maiores do que os obtidos com meio padrão. Além disso, o processo simultâneo de cultivo celular em FBR tubulares e adsorção contínua do meio de cultivo exaurido em coluna de CAG removeu 51 - 79 % de MO e pigmentos. Foi demonstrado que uma proporção de 75 % de meio tratado no meio de alimentação não produz diminuição significativa de produtividade celular (PX) e os resultados foram: concentração celular em estado estacionário (Xs) de 1568 ± 15 mg L-1, PX = 941 mg L-1 d-1, PTN = 42,0 ± 0,6 %, com diminuição de 65 % no custo de meio de cultivo. Por fim, conclui-se que é viável a utilização de processos físico-químicos no tratamento de meio a ser reaproveitado no cultivo de A. platensis, inclusive em FBR tubulares, com apreciável incremento de clorofila-a e proteínas na biomassa obtida em meio tratado. / Arthrospira (Spirulina) platensis have compounds of interest in the food, pharmaceutical and cosmetic industries. Industrial production involves high volumes of water and its viability should contemplate medium reuse, aiming to reduce not only nutrient costs, but also environmental pollution, thus becoming a sustainable process. This work had as main objective the evaluation of A. platensis culture medium reuse through the physicochemical treatments flocculation and adsorption. Thus, this cyanobacterium was cultivated in tubular photobioreactor (PBR) by fed-batch and continuous processes at light intensity 120 µmol photons m-2 s-1 under pH control. Treatment techniques were developed for culture medium from fed-batch process to properly removal of organic matter (OM) and pigments (60 - 96 %), thus allowing its reuse in new cultures. A. platensis was cultivated in treated medium using Erlenmeyer flasks, with the evaluation of parameters such as maximum cell concentration (Xm), chlorophyll content (Chl) and protein content in dry biomass (PTN). For simultaneous flocculation and adsorption with powdered activated carbon (PAC), two flocculants were used: ferric chloride (F) and ferric sulfate (S), as well as different contact times. In the simultaneous process of F flocculation and PAC adsorption, optimum conditions were: PAC = 24.4 mg L-1 and F = 20.3 mg L-1 for 30.4 min contact time; results were: Xm = 4893 ± 33 mg L-1, Chl = 24.3 ± 0.1 mg g-1, PTN = 36.1 ± 0.6 %. Optimal conditions in the simultaneous process of S flocculation and PAC adsorption were: PAC = 40.0 mg L-1 and S = 32.8 mg L-1 for 36.1 min contact time; results were: Xm = 4863 ± 64 mg L-1, Chl = 24.5 ± 0.6 mg g-1, PTN = 60.1 ± 0.6 %. In the sequential process of F flocculation followed by adsorption with granular activated carbon (GAC), optimal conditions were reached at GAC = 108.4 g and F = 10.0 mg L-1 for 30.8 min of residence time, at which Xm = 3140 ± 77 mg L-1, Chl = 35.4 ± 0.2 mg g-1 and PTNPTN = 44.9 ± 0.0 % were obtained. Moreover, medium treated at each optimal condition were also tested in tubular PBRs, reaching values of Xm, Chl and PTN higher than those obtained with standard medium. Furthermore, the simultaneous process of cell cultivation in tubular PBR and continuous adsorption of spent cultivation medium through GAC column removed 51 - 79 % of OM and pigments. It was showed that 75 % of treated medium in the feed medium does not cause significant decrease in cell productivity (PX) and results were: steady-state cell concentration (Xs) = 1568 ± 15 mg L-1, PX = 941 mg L-1 d-1, PTN = 42.0 ± 0.6 %, with 65 % reduction in medium price. At last, it can be inferred that the use of physicochemical processes in medium treatment is feasible for reuse in A. platensis cultivation, including that in tubular PBR, leading to considerable increase in chlorophyll and protein contents of the biomass obtained with treated medium.

Este trabalho tem por objetivo ampliar o conhecimento sobre as teorias de ciclo de vida e de Contabilidade Gerencial investigando a relação existente entre o estágio do ciclo de vida organizacional e os artefatos da Contabilidade Gerencial adotados pelas Pequenas e Médias Empresas (PMEs) que mais cresceram no Brasil entre 2008 e 2010, sendo esta não muito explorada em pesquisas e literatura, contribuindo, deste modo, para um melhor entendimento dos problemas enfrentados pelas PMEs, uma vez que a estas empresas possuem grande relevância na economia e na sociedade Brasileira. Para tanto, foi realizado um estudo envolvendo 37 PMEs, dentre as 250 PMES que mais cresceram no Brasil entre 2008 e 2010, por meio de questionário eletrônico enviado durante o mês de Setembro de 2012 que tinha como objetivo investigar a relação existente entre o estágio do ciclo de vida organizacional e os artefatos de Contabilidade Gerencial adotados pelas 250 PMEs. Sendo uma pesquisa descritiva e quantitativa o tratamento estatístico dos dados foi submetido ao teste de Qui- Quadrado para independência. No que diz respeito aos resultados da pesquisa, foi constatado que, das 37 organizações pesquisadas, 26 estavam no estágio nascimento, oito no estágio crescimento, uma no estágio maturidade e duas no estágio declínio. A identificação dos estágios do ciclo de vida organizacional das empresas pesquisadas foi realizada de forma descritiva e com uma abordagem cross-sectional. Os artefatos de Contabilidade Gerencial foram escolhidos com base nas recentes pesquisas sobre o tema, com especial destaque para a tese de Borinelli (2006) e para cada um dos artefatos escolhidos o teste estatístico foi realizado, concluindo que quatro artefatos dos 12 artefatos escolhidos, possuem relação com o estágio do ciclo de vida, ou seja, sendo este um achado da presente pesquisa, pode-se inferir que é possível que PMEs adotem artefatos que façam mais sentido com relação ao seu ciclo de vida obtendo com isto melhor controle da operação. Sendo assim o trabalho contribuiu para clarificar as possíveis inter-relações entre a o uso de artefatos de Contabilidade Gerencial e o ciclo de vida organizacional de PMEs, contribuindo adicionalmente para criar um arcabouço empírico e metodológico para futuras pesquisas e aprofundamentos em outras PMEs. / This work aims to increase knowledge about the life cycle and Management Accounting theories investigating the relationship between the stage of organizational life cycle and the use of management tools adopted by the 250 fatest growing Small and Medium Enterprises (SMEs) between 2008 and 2010, which is not much explored in research and literature, thus contributing to a better understanding of the problems faced by SMEs, since these companies have great relevance in the Brazilian economy and society. Therefore, a study was conducted involving 37 SMEs, among the 250 fastest growing SMEs in Brazil between 2008 and 2010, through an electronic questionnaire sent during the month of September 2012 which aimed to investigate the relationship between the stage of organizational life cycle and management tools adopted by 250 SMEs. Being a descriptive and quantitative research, statistical treatment of the data was subjected to chi-square test for independence. It was observed that out of the 37 SMEs, 26 were in the birth stage, eight in the growth stage, one at mature stage and two at decline stage. The identification of the stages of organizational life cycle for companies surveyed was performed with a descriptive and cross-sectional approach. Management tools were chosen based on recent research on the subject, with particular emphasis on the Borinelli\'s thesis (2006) and for each of the management tools chosen statistical test was conducted, concluding that four of 12 management tools chosen, have relation to the stage of the life cycle, ie, being a finding of this research, it can be inferred that it is possible for SMEs to adopt management tools that make more sense in relation to its life cycle getting better control of this operation. So the work has helped to clarify the possible inter-relationships between the use of management tools and organizational life cycle of SMEs, contributing further to create an empirical and methodological framework for future research and insights in other SMEs.

Nesta dissertação emprega-se um método simplificado de análise elástica baseado na técnica do meio contínuo para edifícios altos submetidos a terremoto formados por painéis paredes, pórticos e núcleos de seção aberta de parede delgada. Na ligação dos diferentes painéis, supõe-se que existe uma considerável quantidade de diafragmas horizontais rígidos em seu próprio plano, distribuídos continuamente ao longo da vertical 0z. Levando-se em conta a equação constitutiva dos painéis individuais pode-se obter a solução de analise estrutural para o edifício mediante equações diferenciais acopladas para deslocamento e rotações ao longo do eixo vertical do edifício. Com base nesses resultados, todos os esforços internos podem, então, ser obtidos. O método de análise proposto oferece um simples e rápido meio de obtenção da deformada e das forças internas dos diferentes painéis do edifício alto em fases iniciais do projeto. A utilidade e a aproximação do método são examinadas mediante exemplos numéricos, sendo a solução aproximada comparada com aquela obtida com o emprego do método de elementos finitos elaborado pelo programa SAP2000. / This work presents a simplified method of elastic analysis based on the continuous medium technique for tall building structures formed by shear wall panels, frames and core thin walled sections. In order to connect the various panels, it is assumed that there exist a considerable amount of rigid diaphragms continuously distributed along the vertical 0z. The building is subject to lateral earthquake load. Taking into account the constitutive equation of the individual panel, one can achieve a solution through coupled differential equations for displacement and rotation of the building. Based on that, all of the internal forces can be obtained. The analysis is extended to structures formed by singular panel configuration. The proposed method offers a relatively simple and rapid way to obtain the displacements and internal forces of different structural systems of tall buildings, especially indicated for preliminary stages of calculation. The usefulness of the approach and method are illustrated by numerical examples, where the approximated solution is compared with that obtained by finite element calculations.

La dernière génération de récepteurs radio, dotés à la fois d'une grande bande passante et d'une haute résolution, fait de toute observation radio-astronomique une étude spectroscopique. Dans le cas de l'imagerie à grand champ du milieu interstellaire, une telle abondance de données fournit de nouveaux outils de diagnostic, mais pose aussi de nouveaux défis en termes de traitement et d'analyse des données. L'objectif du projet ORION-B est d'observer 5 degrés carrés du nuage moléculaire OB, soit près de la moitité de la surface du nuage, dans toute la bande à 3mm. L'émission de dizaines de traceurs moléculaires à été cartographiée, ce qui inclut CO et ses isotopologues, HCO, HCN, HNC, N$_2$H$^+$, le méthanol, SO, CN...L'accès à des cartes résolues spatialement pour de nombreuse espèces chimiques nous permet d'identifier les meilleurs traceurs de la densité du gaz et de son illumination. Ces cartes ont aussi été soumises à des méthodes d'apprentissage automatique, afin de segmenter le nuage moléculaire en régions caractérisées par une émission moléculaire similaire, et de quantifier les corrélations les plus importantes entre différents traceurs moléculaires, et entre les traceurs et des quantités physiques telles que la densité ou la température des poussières.La grande surface observée, combinée à une haute résolution spatiale et spectrale, permet aussi de caractériser statistiquement la cinématique et la dynamique du gaz. La fraction de quantité de mouvement dans les modes compressifs et solénoïdaux (rotationels) de la turbulence peut être calculée, ce qui montre que le nuage est dominé par des mouvements solenoidaux, tandis que les mouvements compressifs sont concentrés dans deux régions de formation stellaire. Ce résultat est cohérent avec l a très faible efficacité de formation stellaire de ce nuage, et souligne l'importance du forçage compressif pour la formation des étoiles.Les nombreux filaments identifiés dans ce nuage moléculaire ont par ailleurs des densités relativement faibles, et sont très stables vis à vis de l'effondrement gravitationnel. La plupart des filaments sont dépourvus d'étoiles jeunes, mais ils montrent des signes de fragmentation radiale et longitudinale, ce qui indique que de la formation stellaire pourrait à l'avenir y avoir lieu. / The new generation of wide-bandwidth high-resolution receivers turns almost any radio observation into a spectral survey. In the case of wide-field imaging of the interstellar medium, such a wealth of data provides new diagnostic tools, but also poses new challenges in terms of data processing and analysis. The ORION-B project aims at observing 5 square degrees of the OB molecular cloud, or about half of the cloud's surface, over the entire 3mm band. The emission of tens of molecular tracers has been mapped, including CO isotopologues, HCO, HCN, HNC, N$_2$H$^+$, methanol, SO, CN...Having access to spatially resolved maps from many molecular species enables us to identify the best tracers of the gas density and illumination. Machine learning techniques have also been applied to these maps, in order to segment the molecular cloud into typical regions based on their molecular emission, and to quantify the most meaningful correlations of different molecular tracers with each other and with physical quantities such as density or dust temperature.The wide-field coverage, together with the spatial and spectral resolution, also allows to characterize statistically the kinematics and dynamics of the gas. The amount of momentum in the compressive and solenoidal (rotational) modes of turbulence are retrieved, showing that the cloud is dominated by solenoidal motions, with the compressive modes being concentrated in two star-forming regions. This result is in line with the overall very low star formation efficiency of the cloud, and highlights the role of compressive forcing in the star formation process.The numerous filaments identified in the molecular cloud also prove to have rather low densities, and are very stable against gravitational collapse. Most filaments are starless, but they show signs of longitudinal and radial fragmentation, which indicates that star formation might occur later on.

In this thesis, we consider four different problems in membrane filtration, using a different mathematical approach in each instance. We account for the fluid-driven deformation of a filtercake using nonlinear poroelasticity in Chapter 2. By considering feeds with very high and very low particle concentrations, we introduce a quasi-static caking model that provides a suitable approximation to the full model for the physically realistic concentration regimes. We illustrate the agreements and differences between our model and the existing conventional cake-filtration law. In Chapter 3, we introduce a stochastic model for membrane filtration based on the quantised nature of the particles and show how it can be applied for feeds with different particle types and membranes with an interconnected pore structure. This allows us to understand the relation between the effects of clogging on the level of an individual pore and on the macroscopic level of the entire membrane. We conclude by explaining the transition between the discrete and continuous model based on the Fokker--Planck equation. In Chapter 4, we consider the inverse problem of determining the underlying filtration law from the spreading speed of a particle-laden gravity current. We first couple the theory of gravity currents with the stochastic model developed in Chapter~3 to determine a filtration law from a given set of experiments. We then generalise this idea for the porous medium equation, where we show that the position of the front follows a power law for the conventional filtration laws, which allows us to infer the clogging law in certain instances. We conclude the thesis by showing in Chapter 5 how we can combine experimental measurements for the clogging of a depth filter and simple fluid dynamics to accurately predict the pressure distribution in a multi-capsule depth filter during a filtration run.

Aspirations for equality between the English and Welsh languages are widely held in Wales although Welsh is spoken by a minority of the population. Practitioners working through the medium of Welsh face particular challenges which include shortages of resources and limited access to support from Welsh speaking professionals. This thesis describes an intervention over time to strengthen the marginal position of a team of practitioners whose practice takes place through the medium of the Welsh language. Drawing on discursive evidence gathered in a series of team meetings conducted through the medium of Welsh the case study explores the potential of developmental project work to provide a context within which to effect change for practice, professional development and professional identity. The research is grounded in Engeström’s theory of expansive learning and uses methodology based on Vygotsky’s notion of dual stimulation. Forms of discourse analysis is applied to transcripts and textual records of the communicative action of the team. The study charts trajectories of change for the team and team members occurring during the study and beyond. Outcomes have included the establishment of self directed working practices in the development of resources which are valued by local, regional, national and commercial colleagues. The study provides an illustration of how this interventionist approach to support practitioners apply and extend their knowledge and expertise in developmental project work also contributed to professional development through reconstructions of professional identity.

"Opportunistic routing (OR) takes advantages of the spatial diversity and broadcast nature of wireless networks to combat the time-varying links by involving multiple neighboring nodes (forwarding candidates) for each packet relay. This dissertation studies the properties, energy efficiency, capacity, throughput, protocol design and security issues about OR in multihop wireless networks. Firstly, we study geographic opportunistic routing (GOR), a variant of OR which makes use of nodes' location information. We identify and prove three important properties of GOR. The first one is on prioritizing the forwarding candidates according to their geographic advancements to the destination. The second one is on choosing the forwarding candidates based on their advancements and link qualities in order to maximize the expected packet advancement (EPA) with different number of forwarding candidates. The third one is on the concavity of the maximum EPA in respect to the number of forwarding candidates. We further propose a local metric, EPA per unit energy consumption, to tradeoff the routing performance and energy efficiency for GOR. Leveraging the proved properties of GOR, we propose two efficient algorithms to select and prioritize forwarding candidates to maximize the local metric. Secondly, capacity is a fundamental issue in multihop wireless networks. We propose a framework to compute the end-to-end throughput bound or capacity of OR in single/multirate systems given OR strategies (candidate selection and prioritization). Taking into account wireless interference and unique properties of OR, we propose a new method of constructing transmission conflict graphs, and we introduce the concept of concurrent transmission sets to allow the proper formulation of the maximum end-to-end throughput problem as a maximum-flow linear programming problem subject to the transmission conflict constraints. We also propose two OR metrics: expected medium time (EMT) and expected advancement rate (EAR), and the corresponding distributed and local rate and candidate set selection schemes, the Least Medium Time OR (LMTOR) and the Multirate Geographic OR (MGOR). We further extend our framework to compute the capacity of OR in multi-radio multi-channel systems with dynamic OR strategies. We study the necessary and sufficient conditions for the schedulability of a traffic demand vector associated with a transmitter to its forwarding candidates in a concurrent transmission set. We further propose an LP approach and a heuristic algorithm to obtain an opportunistic forwarding strategy scheduling that satisfies a traffic demand vector. Our methodology can be used to calculate the end-to-end throughput bound of OR in multi-radio/channel/rate multihop wireless networks, as well as to study the OR behaviors (such as candidate selection and prioritization) under different network configurations. Thirdly, protocol design of OR in a contention-based medium access environment is an important and challenging issue. In order to avoid duplication, we should ensure only the "best" receiver of each packet to forward it in an efficient way. We investigate the existing candidate coordination schemes and propose a "fast slotted acknowledgment" (FSA) to further improve the performance of OR by using a single ACK to coordinate the forwarding candidates with the help of the channel sensing technique. Furthermore, we study the throughput of GOR in multi-rate and single-rate systems. We introduce a framework to analyze the one-hop throughput of GOR, and provide a deeper insight on the trade-off between the benefit (packet advancement, bandwidth, and transmission reliability) and cost (medium time delay) associated with the node collaboration. We propose a local metric named expected one-hop throughput (EOT) to balance the benefit and cost. Finally, packet reception ratio (PRR) has been widely used as an indicator of the link quality in multihop wireless networks. Many routing protocols including OR in wireless networks depend on the PRR information to make routing decision. Providing accurate link quality measurement (LQM) is essential to ensure the right operation of these routing protocols. However, the existing LQM mechanisms are subject to malicious attacks, thus can not guarantee to provide correct link quality information. We analyze the security vulnerabilities in the existing link quality measurement (LQM) mechanisms and propose an efficient broadcast-based secure LQM (SLQM) mechanism, which prevents the malicious attackers from reporting a higher PRR than the actual one. We analyze the security strength and the cost of the proposed mechanism. "

Ettlia oleoabundans, a freshwater green microalga, was grown under different environmental conditions to study its growth, lipid yield and quality for a better understanding of the fundamental physiology of this oleaginous species. E. oleoabundans showed steady increase in biomass under low temperature and low light intensity, and at high temperature lipid cell content significantly increased independent of nitrate depletion. Studies on light quality showed that red light treatment did not change the biomass concentration, but stimulated lipid yield especially oleic acid, the most desirable biodiesel precursor. Moreover, no photoreversibility in lipid production was observed when applying alternating short-term red and far-red lights, which left the phytochrome effect still an open question. In addition, carbon dioxide enrichment via an air sparging system significantly boosted exponential growth and increased carbon conversion efficiency. Finally, a practical study demonstrated the feasibility of growing E. oleoabundans for high lipid production using a diluted agricultural anaerobic waste effluent as the medium. Together, these studies showed the potential of E. oleoabundans as a promising high yield feedstock for the production of high quality biodiesel.