PB2 ist ein essentieller Bestandteil der trimeren RNA abhängigen RNA Polymerase von Influenzaviren und ist bekannt für seine Schlüsselrolle in der Bestimmung des Viruswirtsspektrums. Diese Arbeit diente der Identifizierung neuer Interaktionspartner von PB2 eines saisonalen und eines hochpathogenen Influenzavirus Stammes im Kontext infizierter humaner alveolar Epithelzellen (A549) unter Einsatz massenspektrometrischer Analysen. Die anschließende Untersuchung ausgewählter zellulärer Interaktoren hatte zum Ziel, deren Einfluss auf den Replikationszyklus der Influenzaviren zu bestimmen, sowie Unterschiede in ihrer Relevanz für das saisonale und das hochpathogene Virus aufzuzeigen. Die Erzeugung und Nutzung von Influenzaviren die einen Strep-tag an ihrem PB2 Protein tragen ermöglichte eine Anreicherung von PB2 und seiner Interaktionspartner. Die anschließende massenspektrometrische Analyse identifizierte 22 potentielle PB2 Interaktionspartner. Eine Auswahl an 13 Proteinen wurde tiefer gehend analysiert und eine Komplexbildung mit PB2 konnte für 9 Proteine bestätigt werden. Darüber hinaus zeigten 11 Proteine einen Polymerase stimulierenden bzw. hemmenden Effekt. Das Polymerase stimulierende Protein HSPA8 wurde zur weiteren Untersuchung ausgewählt. Während ein Einfluss von HSPA8 auf den hochpathogenen Influenzastamm nicht abschließend geklärt werden konnte, wurde seine Bedeutung für den Vermehrungszyklus des saisonalen Stammes aufgezeigt. Die Überexpression von HSPA8 führte zu einer Steigerung der Polymerase-Aktivität, wohingegen die Erniedrigung des HSPA8 Spiegels in einer Verringerung der viralen Replikation und der Polymerase-Aktivität resultierte. Interessanterweise führte die Erniedrigung des HSPA8 Spiegels auch zu stark verminderter PB2-Expression, jedoch nur im Falle des saisonalen Influenzastammes. Dieser Befund deutet auf eine Rolle von HSPA8 als PB2-Chaperon, notwendig für Proteinstabilität von saisonalen aber nicht hochpathogenen Influenzaviren, hin. / PB2 is an essential component of the influenza virus trimeric RNA dependent RNA polymerase and is known to play a key role in virus host range determination. Here, a combined affinity-purification/mass spectrometric approach was performed to identify novel interaction partners of PB2 of seasonal and highly pathogenic viral strains in infected human alveolar epithelial cells (A549). The subsequent analysis of selected cellular interaction partners aimed to determine the influence of these proteins on the replication cycle, as well as to determine differences in their relevance for the seasonal and the highly pathogenic influenza virus strain. Generation and use of recombinant influenza viruses carrying a Strep-tag at their PB2 protein allowed for enrichment of PB2 and its interaction partners. The subsequent mass spectrometric analysis identified 22 potential PB2 interaction partners. A selection of 13 proteins was further analyzed, and co-precipitation with PB2 was confirmed for 9 proteins. Moreover, an inhibitory or stimulatory effect on polymerase activity was observed for 11 proteins. The polymerase stimulating protein HSPA8 was selected for further investigation. While the influence of HSPA8 on the highly pathogenic strain remained unclear, its importance for seasonal influenza virus life cycle was demonstrated. Overexpression of HSPA8 resulted in increased polymerase activity while HSP8 knock down resulted in reduction of viral replication and viral polymerase activity. Intriguingly, the knock down of HSPA8 led to a strong decrease of PB2 protein expression. However, this was only observed for seasonal PB2. These results indicate a role of HSPA8 as a PB2 chaperone, necessary for protein stability of seasonal but not highly pathogenic influenza virus.

Uma decomposição de um grafo G é um conjunto D = {H_1,... , H_k } de subgrafos de G dois-a-dois aresta-disjuntos que cobre o conjunto das arestas de G. Se H_i é isomorfo a um grafo fixo H, para 1<=i<=k, então dizemos que D é uma H-decomposição de G. Neste trabalho, estudamos o caso em que H é um caminho de comprimento fixo. Para isso, primeiramente decompomos o grafo dado em trilhas, e depois fazemos uso de um lema de desemaranhamento, que nos permite transformar essa decomposição em trilhas numa decomposição somente em caminhos. Com isso, obtemos resultados para três conjecturas sobre H-decomposição de grafos no caso em que H=P_\\ell é o caminho de comprimento \\ell. Dois desses resultados resolvem versões fracas das Conjecturas de Kouider e Lonc (1999) e de Favaron, Genest e Kouider (2010), ambas para grafos regulares. Provamos que, para todo inteiro positivo \\ell, (i) existe um inteiro positivo m_0 tal que se G é um grafo 2m\\ell-regular com m>=m_0, então G admite uma P_\\ell-decomposição; (ii) se \\ell é ímpar, existe um inteiro positivo m_0 tal que se G é um grafo m\\ell-regular com m>=m_0, e G contém um m-fator, então G admite uma P_\\ell-decomposição. O terceiro resultado diz respeito a grafos altamente aresta- conexos: existe um inteiro positivo k_\\ell tal que se G é um grafo k_\\ell-aresta-conexo cujo número de arestas é divisível por \\ell, então G admite uma P_\\ell-decomposição. Esse resultado prova que a Decomposition Conjecture de Barát e Thomassen (2006), formulada para árvores, é verdadeira para caminhos. / A decomposition of a graph G is a set D = {H_1,...,H_k} of pairwise edge-disjoint subgraphs of G that cover the set of edges of G. If H_i is isomorphic to a fixed graph H, for 1<=i<=k, then we say that D is an H-decomposition of G. In this work, we study the case where H is a path of fixed length. For that, we first decompose the given graph into trails, and then we use a disentangling lemma, that allows us to transform this decomposition into one consisting only of paths. With this approach, we tackle three conjectures on H-decomposition of graphs and obtain results for the case H=P_\\ell is the path of length \\ell. Two of these results solve weakenings of a conjecture of Kouider and Lonc (1999) and a conjecture of Favaron, Genest and Kouider (2010), both for regular graphs. We prove that, for every positive integer \\ell, (i) there is a positive integer m_0 such that, if G is a 2m\\ell-regular graph with m>=m_0, then G admits a P_\\ell-decomposition; (ii) if \\ell is odd, there is a positive integer m_0 such that, if G is an m\\ell-regular graph with m>=m_0 containing an m-factor, then G admits a P_\\ell-decomposition. The third result concerns highly edge-connected graphs: there is a positive integer k_\\ell such that if G is a k_\\ell-edge-connected graph whose number of edges is divisible by \\ell, then G admits a P_\\ell-decomposition. This result verifies for paths the Decomposition Conjecture of Barát and Thomassen (2006), on trees.

The focus of interest in this thesis is the social and personal trajectories of men and women who were born in the Soviet Union in the 1970-1980s and then, after growing up in post-Soviet Russia in the 1990s in an atmosphere of change and uncertainty, decided to exploit the opportunities to go abroad to study and work that started opening up in the early and mid-1990s. The thesis analyses these moves as the individual strategies of either escaping or waiting on the career insecurities in Russia, or consciously enhancing one's social standing and professional and educational capital. It traces their social and professional trajectories, showing that, apart from developing the desired expertise and gaining experience, these Russians went through intensive changes in their self-identifications and senses of belonging, including the acquisition of new habits of mobility, international social networks and cosmopolitan dispositions. This thesis argues that, while their Soviet-Russian cultural past and their belonging to a particular social group of 'Soviet intelligentsia' was still important to them, they continuously acquired new social, cultural and cosmopolitan forms of capital that influenced their coming back to Russia as different persons from their contemporaries who had stayed in the country. They brought with them new dispositions and new social practices resulting from their active comparisons of their lives in Russia and Britain, and in many respects they actively maintained their differences in creating clubs for returnees. While able to integrate successfully into the emerging Russian middle classes, they still expressed the cultural and intellectual heritage of the past Soviet intelligentsia, now reborn in the guise of Westernizing attitudes and practices, different degrees of cosmopolitan patriotism, intellectual pursuits, a quest for education and self-development, interest in world travel, an ethical concern for sustainability, opposition to excessive consumerism in Russia and conspicuous practices of status performance. The materials for this research were mainly gathered through the use of semi-structured in-depth interviews, one third of them longitudinal, with informants talking to the researcher several times during the course of fieldwork between 2007 and 2012. Some additional participant observation has been conducted in informal Russian circles in the UK and among returnees from Britain in Russia. This research consists of an ethnography with elements of a biographical approach. This has made the researcher attentive to the inclusion of a certain event within a person's whole biography, aimed at putting the period researched within the context of the past and future lives of the informant. The participants of this research were aged between 22 and 40 and belonged to a transition cohort generation (Miller 2000), as they had all passed their childhoods in the Soviet Union, their adolescence and teenage years coinciding with the period of dissolution of the USSR, with the transitional break up of one system and the formation of another, while their young adulthood developed in post-Soviet Russia. They were mainly single when they initiated their move to Britain, and had various professional profiles within the broadly defined groups of 'highly skilled' and 'highly educated', the latter term being preferred in this research. The dissertation includes an introduction, four ethnographic chapters, a conclusion and one appendix. The introduction presents the historical and research context, the methodology and the design of the study. The first chapter traces the professional and educational trajectories of participants, while the second chapter focuses on informants' spatial mobility and habits of extensive travel acquired during the move to Britain. The third chapter deals with the negotiation of informants' belonging to a particular cultural and social past, which is associated both with Russian-Soviet culture and with their social status as the children of Soviet-era intelligentsia. The fourth chapter argues that, while belonging to Soviet intelligentsia families was still important for informants' self-identifications in Britain, new social, cultural and cosmopolitan forms of capital were acquired during this period, resulting in new cosmopolitan dispositions, ethics and moral values, and new practices socially remitted (Levitt 2001) from Britain. The conclusion places this ethnography within the state-of-the-art research on the mobilities of Russians to the UK.

"A flow control method for minimizing losses in a highly loaded compressor blade was analyzed. Passive and active flow control experiments with vortex generator jets were conducted on a seven blade linear compressor cascade to demonstrate the potential application of passive flow control on a highly loaded blade. Passive flow control vortex generator jets use the pressure distribution generated by air flow over the blade profile to drive jets from the pressure side to the suction side. Active flow control was analyzed by pressuring the blade plenum with an auxiliary compressor unit. Active flow control decreased profile losses by approximately 37 % while passive flow control had negligible impact on the profile loss of a highly loaded blade. Passive flow control was able to achieve a jet velocity ratio, jet velocity to upstream velocity, of 0.525. The success of active flow control with a velocity ratio of 0.9 suggests there is potential for passive flow control to be effective. The research presented in this thesis is motivated by the potential savings in the applications of passive flow control in gas turbine axial compressors by increasing the aerodynamic load of each stage. Increased stage loading that is properly controlled can reduce the number of stages required to achieve the desired pressure compression ratio."

Made available in DSpace on 2016-04-28T20:16:25Z (GMT). No. of bitstreams: 1 2007- Luiz Figueira Pinto.pdf: 1581116 bytes, checksum: 36931ba33454d8c934e6419c55b06974 (MD5) Previous issue date: 2007-12-13 / Palicourea marcgravii (Pm) is the most important toxic plant in Brazil. It is responsible for about half of all bovine deaths by natural poisoning in the country. The poisoning has a hyperacute evolution resulting in sudden death, which is attributed to the monofluoroacetic acid. This substance has high toxicity to several mammals, including humans. The homeopathic therapeutics uses ultra-highly diluted and dynamized solutions and there is enough evidence to investigate them as possible protection against poisonings. The aims of the present work were to compare the toxic effects of aqueous (AE) and hydroalcoholic (mother tincture - MT) extracts of Pm in rats, evaluate the effects of ultra-highly diluted and dynamized solutions (Pm 6CH and Pm 30CH) over the development of tolerance to the toxic effects of Pm and evaluate clinical, necroscopic and histopathological alterations in nonintoxicated rats treated with these solutions. AE and MT groups were formed of 10 animals each which received the extract in doses of 0.4g/kg, 0.8g/kg, 2g/kg and 4g/kg, intragastrically. The UD6EA and UD30EA groups were formed of five rats each, which received respectively 1 mL of Pm 6CH e Pm 30CH solutions, by oral route, three times a day, for eight days. Then, they were intoxicated with 2g/kg of Pm aqueous extract, intragastrically and received the correspondent ultra-highly diluted and dynamized preparations hourly until death. The UD6 and UD30 groups were formed of five rats each and received respectively 1 mL of Pm 6CH and Pm 30CH, orally, three times a day for 63 days. The animals were evaluated using clinical parameters, including the direct observation of their behavior at the open field and at the elevated plus-maze, and the study of the macro and microscopic lesions. Hyperacute death occurred after administration of the doses of 0.4g/kg, 0.8g/kg, 2g/kg e 4g/kg. In the AE group, prostration and nervous hyperexcitability followed or not by convulsive crisis were observed. In the MT group, the animals presented marked nervous depression without convulsion. Hepatic congestion and evidence of cardiac dilation were observed in the necropsy. Hydropic vacuolar degeneration of the renal distal convoluted tubules and congestion of several organs were observed in the histopathological examination. The latencies for the emergence of the first clinical signs, the convulsions and death occurrence were different in the animals of groups AE1 (Pm 2g/kg), UD6EA and UD30EA, but was considered inadequate the animals amount. Groups UD6 and UD30 did not show any clinical, behavioral, necroscopical or histopathological differences when compared to the control group. The conclusions were that the aqueous extract causes nervous excitability and convulsions while the mother tincture causes nervous depression. There is cumulative effect of the toxic substances present in the plant, and there is not evidence that the ultra-highly diluted and dynamized preparation increases the tolerance to Pm intoxication. / A Palicourea marcgravii (Pm), a planta t?xica mais importante no Brasil, ? respons?vel por cerca da metade das mortes por intoxica??o natural em bovinos no Pa?s. A intoxica??o cursa com evolu??o superaguda e morte s?bita, atribu?da ao ?cido monofluoroac?tico, subst?ncia de alta toxidez para diversos mam?feros, inclusive o homem. A terap?utica homeop?tica emprega solu??es ultradilu?das e dinamizadas e h? evid?ncias suficientes para explor?-la como poss?vel prote??o contra intoxica??es. Os objetivos deste trabalho foram comparar os efeitos t?xicos dos extratos aquoso (EA) e hidro-alco?lico (tintura-m?e - TM) de Pm em ratos e avaliar o efeito das solu??es ultradilu?das e dinamizadas (Pm 6CH e Pm 30CH) sobre a toler?ncia e a??o t?xica da planta e avaliar a ocorr?ncia de altera??es cl?nicas, necrosc?picas e histopatol?gicas em ratos n?o-intoxicados tratados com essas solu??es. O EA, a TM, a Pm 6CH e a Pm 30CH foram administrados a 49 ratos distribu?dos em seis grupos-teste; dois grupos adicionais foram mantidos como controle. Os grupos EA e TM foram constitu?dos por 10 animais cada, que receberam doses que variaram de 0,4g/kg, 0,8g/kg, 2g/kg e 4g/kg. Os grupos UD6EA e UD30EA foram constitu?dos por cinco ratos cada e receberam 1mL das solu??es Pm 6CH e Pm 30CH, respectivamente, por via oral, tr?s vezes ao dia, e ap?s oito dias 2g/kg do extrato aquoso de Pm, por via intrag?strica. Os grupos UD6 e UD30, constitu?dos por cinco ratos cada, receberam 1mL de Pm 6CH e Pm 30CH, respectivamente, por via oral, tr?s vezes ao dia, durante 63 dias. Os animais foram avaliados por par?metros cl?nicos, comportamentais (campo aberto e labirinto em cruz elevado), achados de necropsia e exames histopatol?gicos. Ocorreu morte superaguda com as doses de 0,4g/kg, 0,8g/kg, 2g/kg e 4g/kg. No grupo EA observaram-se prostra??o e hiperexcitabilidade nervosa, seguida, ou n?o, por crise convulsiva e no grupo TM depress?o nervosa acentuada, sem convuls?o. Havia ainda p?los eri?ados, dispn?ia, cianose de extremidades, e hipotermia. ? necropsia observaram-se f?gado congesto e dilata??o card?aca e pelo exame histopatol?gico, degenera??o hidr?picovacuolar em t?bulos contornados distais dos rins e congest?o em v?rios ?rg?os. Houve diferen?as nas lat?ncias para o aparecimento dos primeiros sinais cl?nicos, de convuls?o e ocorr?ncia de morte entres os grupos UD30EA, UD6EA e EA1 (Pm 2g/kg), mas o numero de animais foi considerado pequeno para se atribuir efeito protetor das solu??es ultradilu?das e dinamizadas ? intoxica??o pela planta. Os grupos UD6 e UD30 n?o apresentaram diferen?as cl?nicas, comportamentais ou necrosc?picas em compara??o com o grupo controle. Conclui-se que o extrato aquoso produz excitabilidade nervosa e convuls?o e a tintura-m?e depress?o nervosa, que h? efeito acumulativo e que as solu??es ultradilu?das e dinamizadas n?o induziram aumento ponderal da toler?ncia aos efeitos t?xicos da Pm e n?o produziram altera??es no estado de sa?de dos animais sadios.

Esse trabalho descreve a evolução espacial e temporal da dispersão de um poluente inerte e passivo em uma CLP altamente convectiva simulada com um modelo LES. A versão do modelo LES utilizado foi desenvolvida por Moeng (1984) e modificada por Sullivan et al. (1994). A condição de quase-equilíbrio é verificada através da energia cinética turbulenta (ECT) total integrada na CLP. Os perfis verticais dos momentos estatísticos de primeira, segunda e terceira ordem, concordam com os prognósticos da teoria da similaridade da camada de mistura apresentados na literatura. Os termos da equação de ECT estão em balanço e o transporte de ECT devido às flutuações de pressão é um termo fonte na região próxima à superfície. Os espectros espaciais apresentam uma região de subintervalo inercial com inclinação proporcional a k^(-5/3), onde as relações de isotropia são reproduzidas para a componente vertical de velocidade. O valor estimado da constante de Kolmogorov é 0,52. Resultados equivalentes foram obtidos para os espectros temporais de velocidade. Os espectros das componentes de velocidade apresentam uma região de produção bem definida, permitindo estimar as escalas de comprimento dos turbilhões mais energéticos. Nos espectros espaciais, os comprimentos de onda associados aos turbilhões mais energéticos são aproximadamente constantes e iguais a 1,3 zi. Os valores estimados através dos espectros temporais são 1,5 vezes maiores. Esses resultados confirmam as restrições da aplicação da hipótese de Taylor em uma CLP em condições altamente convectivas. No caso de um poluente emitido por uma fonte área contínua localizada próxima à superfície, representativo das emissões de CO na região metropolitana de São Paulo, o grau de limpeza da CLP está relacionado à intensidade dos processos de entranhamento no topo. As abordagens euleriana e lagrangiana para a descrição da dispersão de um poluente emitido por fonte pontual contínua são similares para alturas elevadas e reproduzem o comportamento esperado das plumas em condições convectivas, quando estão associadas ao modelo LES. Essa concordância confirma a hipótese levantada neste trabalho de que o modelo LES pode ser utilizado como uma ferramenta de validação de modelos operacionais de dispersão. / This work describes the spatial and temporal evolution of the dispersion of an inert and passive pollutant in a highly convective planetary boundary layer (PBL) simulated by LES model. The LES model used here was developed by Moeng (1984) and modified by Sullivan et al. (1994). The quasi-stationary state is verified by total turbulent kinetic energy (TKE) integrated in the PBL. The vertical profiles of the first, second and third order statistical moments, agreed with the predictions of the mixed layer similarity theory available in the literature. The TKE equation terms are balance and TKE pressure-transport is a source in the near to the surface. The spatial spectra show a inertial subrange proportional k^(-5/3), were isotropy relations are reproduced for vertical velocity. The Kolmogorov constant estimated is 0,52. The equivalent results are obtained for temporal wind velocity spectra. The wind velocity spectra show very well defined production region, allowing to estimate the spectral peak wavelength and characteristic length. In the spatial spectra cases, the horizontal velocity peak wavelengths are approximately constants and equal to 1.3 zi. The values obtained from temporal spectra are 1.5 larger. The same factor is found for temporal and spatial estimates. These results confirm the restrictions to the Taylor’s hypothesis applications in highly convective PBL. The concentration of pollutant released from a continuous area source located near to the surface, representing CO emissions in São Paulo city, is strongly dependent on the intensity of the entrainment at the top of PBL. The eulerian and lagrangian approaches are equally capable to describe the dispersion of continuous elevated point source located in PBL, reproducing the plume behaviour for convective conditions, when associated to LES model. This agreement indicates that LES model can be used as a tool to validated operational dispersion models.

Thesis (MPH.) --University of Limpopo, 2018 / Background: The prevalence of HIV in South Africa has increased largely due to the combined effect of new infections, and a successfully expanded antiretroviral treatment programme, which has increased survival among people living with HIV. As the up-scaling of patients on ART has been increased, the aim of the current study was to investigate the variations of the clinical outcomes between patients initiated with CD4 < 350 and of those above 350 after the implementation of the new eligibility criteria for ARV therapy. Methods The current study used quantitative approach to retrospectively review a total of 488 records of adult patient who were registered in health facilities which were purposefully sampled from Sekhukhune District of Limpopo Province. SPSS version 23.0 was used to analyse data. Results Approximately 60% of the patients initiated on ART were having CD4 count <350 and male patients were more at 74% as compared to females at 54.7%. Patients who started ART with a baseline CD4 >350 had a high rate of lost to follow up within 3 months after start of ART at 15% than those with a baseline CD4 <350 at 10.2. More patients were lost to follow-up shortly after starting treatment at 3 months at an average of 13.8% in both CD4 counts. Majority of patients retained in care were those who started ART treatment with a baseline CD4<350 at 87.4%. Viral load completion rate at 12 months was higher than that of 6 months, at 86.8 and 80.5 respectively. Patients with a baseline CD4 >350 suppressed more than those who started ART with a baseline CD4 <350 at both 6 and 12 months at >90% suppression rate. Lastly, most of the patients died within 3 months of ART treatment and had a baseline CD4 < 350 than at 2.4% those with a baseline CD4 >350 at 0.6%. Conclusions The implementation of the new eligibility criteria of ART initiation improves the clinical outcome of patients on ART. There are still patients that are missed to be monitored viral load bloods which play a key role in determining the clinical outcomes of patients. Clinicians and nurses should adhere to the recommended time frames for monitoring of ART patients to improve clinical outcomes. Keywords: HIV/AIDS, antiretroviral therapy, clinical outcome, ART initiation; Eligibility Criteria;

Measles remains a major global public health problem. Attainment of high population immunity to measles through vaccination is necessary to control this disease. Children infected with HIV infection often experience secondary measles vaccine failure by 2 years of age, making them susceptible to measles. It is not clear whether HIV-infected children on Highly Active Antiretroviral Treatment (HAART), older than 2 years, have a higher risk of measles than HIV-uninfected children. This retrospective cohort study, guided by the proximate determinants framework, was conducted to compare the risk of measles between HIV-infected children on HAART (exposed) and HIV-uninfected peers (unexposed). The age group with the highest measles susceptibility in the exposed children, which could inform timing for revaccination, was investigated. The role of age at initiation of HAART, low CD4+ count, and undernutrition as predictors of the risk of measles in the exposed children was examined. Univariate, bivariate, and binomial logistic regression analytical procedures were used in data analysis. Results showed no significant difference in the risk of measles between exposed and unexposed children. The age groups 5 to 9 years and 2 to 4 years were the first and second most affected by measles among the exposed children. Undernutrition (stunting) was a significant predictor of measles in exposed children (odds ratio of 4.14, p = 0.02), while age at initiation of HAART and CD4+ count prior to measles exposure were not. The study findings provide evidence to inform vaccination policy and nutrition care for HIV-infected children on HAART in Uganda, so as to reduce their risk of measles illness and mortality, thus contributing to positive social change for the children and the country.

Academics and lay persons alike freely acknowledge that principals exert enormous influence over the creation, maintenance and enhancement of the learning environment in schools. They recognise that a turbulent educational world presents principals with multiple challenges in sustaining the conditions necessary for student achievement, and that some principals are more successful in this endeavour than others. This small-scale qualitative study uses a semi-structured interview process to gather data from five Chairpersons of Boards of Trustees who have appointed a principal within the preceding twelve months. The study discusses the professional capabilities that theoretical and empirical research suggests distinguish highly effective principals from capable performers. It adopts a bipartite approach to the literature, examining both academic understandings and the degree to which available official publications inform the thinking of Boards of Trustees prior to embarking on the principal appointment process. The study then explores the extent to which these understandings influence the decision-making of five Boards of Trustees in appointing a new principal. Research findings reveal a dichotomy between the theory underpinning concepts of highly effective principals and the practice of Boards of Trustees in appointing a principal. Largely unaware of the academic literature and inadequately informed by official publications, Boards of Trustees adopt a problematic generic recruitment and selection process. Uncritical acceptance of the professional knowledge and standing of external consultants and misplaced trust in the advice they proffer leads Boards to proceed on a questionable perceptual basis. Secure in the knowledge that they have obtained the educational expertise they freely acknowledge they lack, Boards are further exposed to prevailing market discourses and internal prejudices which undermine their ability to identify and appoint a principal who possesses the capabilities necessary to exercise highly effective, contextually specific leadership. This study suggests that the autonomy of Boards of Trustees in their role as employer be sustained but supported through the mandatory appointment of an appropriately qualified advisor and that the involvement of existing advisors be further scrutinized.

The InGaN system provides the opportunity to fabricate light emitting devices over the whole visible and ultraviolet spectrum due to band-gap energies E[subscript g] varying between 3.42 eV for GaN and 1.89 eV for InN. However, high In content in InGaN layers will result in a significant degradation of the crystalline quality of the epitaxial layers. In addition, unlike other III-V compound semiconductors, the ratio of gallium to indium incorporated in InGaN is in general not a simple function of the metal atomic flux ratio, f[subscript Ga]/f[subscript In]. Instead, In incorporation is complicated by the tendency of gallium to incorporate preferentially and excess In to form metallic droplets on the growth surface. This phenomenon can definitely affect the In distribution in the InGaN system. Scanning electron microscopy, room temperature photoluminescence, and X-ray diffraction techniques have been used to characterize InGaN layer grown on InN and InGaN buffers. The growth was done on c-plane sapphire by MOCVD. Results showed that green emission was obtained which indicates a relatively high In incorporation. / Singapore-MIT Alliance (SMA)