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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Broad-Band Antireflection Coatings for Improved Grating-External-Cavity Diode Laser Performance

Guo, Liqiang 08 1900 (has links)
In this thesis, strong optical feedback is utilized to realize broad-band wavelength tuning and to stabilize the frequency of a semiconductor diode laser in a grating-external-cavity (GEC) configuration. To reach the regime of strong optical feedback, the laser facet through which the feedback occurs has to be antireflection (AR) coated. Multi-layer AR coatings were designed using SiO2, Si3N4, SiOxNy, and a:Si for specific laser waveguide structures, and were fabricated by an electron cyclotron resonance, plasma enhanced, chemical vapor deposition (ECR-PECVD) system. The film thickness and refractive index were monitored by in situ ellipsometry during the deposition. This scheme permitted very low reflectivities, in the order of 5 x 10-4, to be readily and reproducibly obtained. The diode laser thus obtained was used in a strong feedback configuration. Light emitted from the coated facet was collimated and fed back onto the laser cavity after being reflected off a diffraction grating. The diffraction grating provides frequency selectivity, which is a desirable feature for obtaining a stable single longitudinal mode laser. The laser in this configuration oscillated in a single mode with a greater than 30 dB side mode suppression ratio and a wide tuning range. / Thesis / Master of Applied Science (MASc)
22

The perception of broad–based black economic empowerment across agricultural businesses / Olivier, D.

Olivier, Dewald January 2011 (has links)
Broad Based Black Economic Empowerment could possibly be the utmost strategic issue, challenge, threat and potential opportunity facing businesses of all sizes, structures and shapes currently in South Africa. Broad–Based BEE is a government initiative to promote economic transformation in order to enable meaningful participation in the economy by black people. Broad–Based BEE is a reality and a business imperative. Broad–based BEE already have a huge impact in the way business is done in South Africa by large corporate entities, family businesses, small and medium sized businesses and professional practitioners. Broad–based BEE affects almost every participant in the South African economy. Broad–Based BEE can be divided into three components, which holds the seven elements of Broad–Based BEE, namely direct empowerment, human resource development and indirect empowerment. These elements include Equity Ownership, Management, Employment Equity, Skills Development, Preferential Procurement, Enterprise Development and Corporate Social Investment. The agricultural businesses in South Africa have implemented unique types of Broad–Based BEE strategies to conform to Broad–Based BEE. These strategies include shareholding by external Broad–Based BEE companies, and registering Broad–Based BEE employee trusts that obtains shareholding in the company. According to the AgriBEE Framework its vision is to pursue Broad–Based BEE in support of a United and Prosperous Agricultural Sector. The objectives of AgriBEE as described by the AgriBEE Steering Committee are to facilitate broad–based black economic empowerment in the agricultural sector by implementing initiatives to include Black South Africans at all levels of agricultural activity and enterprises along the entire agricultural value chain by following certain steps and ideologies. The contribution of the agribusinesses has some clear indications of shortcomings within the industry as well as and indication of possible elements to be pursued in future. There are however also serious implications to the respondents actions and attitude towards Broad–Based BEE now and in future. It also very apparent that the agribusiness does not distance themselves from the Broad–Based BEE Act and its requirements as well as the consequences thereof. The agribusiness industry is actively involved in Broad–Based BEE. / Thesis (MBA)--North-West University, Potchefstroom Campus, 2012.
23

The perception of broad–based black economic empowerment across agricultural businesses / Olivier, D.

Olivier, Dewald January 2011 (has links)
Broad Based Black Economic Empowerment could possibly be the utmost strategic issue, challenge, threat and potential opportunity facing businesses of all sizes, structures and shapes currently in South Africa. Broad–Based BEE is a government initiative to promote economic transformation in order to enable meaningful participation in the economy by black people. Broad–Based BEE is a reality and a business imperative. Broad–based BEE already have a huge impact in the way business is done in South Africa by large corporate entities, family businesses, small and medium sized businesses and professional practitioners. Broad–based BEE affects almost every participant in the South African economy. Broad–Based BEE can be divided into three components, which holds the seven elements of Broad–Based BEE, namely direct empowerment, human resource development and indirect empowerment. These elements include Equity Ownership, Management, Employment Equity, Skills Development, Preferential Procurement, Enterprise Development and Corporate Social Investment. The agricultural businesses in South Africa have implemented unique types of Broad–Based BEE strategies to conform to Broad–Based BEE. These strategies include shareholding by external Broad–Based BEE companies, and registering Broad–Based BEE employee trusts that obtains shareholding in the company. According to the AgriBEE Framework its vision is to pursue Broad–Based BEE in support of a United and Prosperous Agricultural Sector. The objectives of AgriBEE as described by the AgriBEE Steering Committee are to facilitate broad–based black economic empowerment in the agricultural sector by implementing initiatives to include Black South Africans at all levels of agricultural activity and enterprises along the entire agricultural value chain by following certain steps and ideologies. The contribution of the agribusinesses has some clear indications of shortcomings within the industry as well as and indication of possible elements to be pursued in future. There are however also serious implications to the respondents actions and attitude towards Broad–Based BEE now and in future. It also very apparent that the agribusiness does not distance themselves from the Broad–Based BEE Act and its requirements as well as the consequences thereof. The agribusiness industry is actively involved in Broad–Based BEE. / Thesis (MBA)--North-West University, Potchefstroom Campus, 2012.
24

O papel da reação em cadeia da polimerase (PCR) de largo espectro no diagnóstico etiológico da sepse / The role of broad-range polymerase chain reaction (PCR) in the etiologic diagnosis of sepsis

Gozzi, Aline 01 August 2014 (has links)
A sepse é responsável por uma alta taxa de internação hospitalar e morbimortalidade. Devido à gravidade do quadro clínico e às limitações dos métodos tradicionais para identificação e isolamento bacteriano, é recomendado o início empírico de antimicrobiano(s) de largo espectro. O desenvolvimento da biologia molecular, particularmente da reação em cadeia da polimerase (PCR), tornou possível o diagnóstico rápido de agentes infecciosos. Entretanto, devido à diversidade dos possíveis agentes etiológicos na sepse, a utilização da PCR com primers específicos para cada agente se torna pouco prática. Com a PCR de largo espectro é possível que em uma só reação se identifique qualquer bactéria, possibilitando um tratamento precoce e direcionado. Desta forma, este trabalho teve como objetivo avaliar o papel da PCR de largo espectro no diagnóstico etiológico de pacientes com sepse e a comparação desta técnica com os métodos tradicionais de cultura. Foram incluídos 74 pacientes com diagnóstico de sepse atendidos na Unidade de Emergência do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto USP e 14 voluntários sadios. Foi realizada a extração do DNA do soro, plasma e buffy-coat dos pacientes, seguida da realização da PCR de largo espectro com dois diferentes pares de primers, e sequenciamento das amostras positivas. Dos 74 pacientes, 39 (53%) eram homens; a média de idade foi 55 ± 19 anos; 37 (50%) tiveram sepse grave e 37 (50%) choque séptico; e a mortalidade foi 51%. A maioria das infecções primárias teve origem respiratória (66%), seguida de infecções gênito-urinárias (20%). A hemocultura foi positiva em 22 (30%) pacientes, e sua positividade foi significativamente maior em pacientes mais velhos (p< 0,05) e com valores mais altos de proteína C reativa (CRP) (p< 0,05). A PCR de largo espectro foi positiva em 44 (59%) pacientes considerando os dois pares de primers, sendo sua positividade significativamente maior que a da hemocultura (p< 0,001). Para o par Bak11W/Bak2 ela foi positiva em 25 (34%) pacientes, e para o par Taf/Tar, em 29 (39%) pacientes. Em relação às frações do sangue, amostras de 24 pacientes foram positivas na fração soro; 22 na fração plasma; e 18 na fração buffy-coat. Nenhuma característica clínica ou demográfica dos pacientes influenciou a positividade da PCR de largo espectro. A PCR de largo espectro foi negativa em todas as frações do sangue dos voluntários sadios. A sensibilidade, especificidade, valor preditivo positivo e valor preditivo negativo da PCR foram 59%, 100%, 100% e 32%, respectivamente. Em 40 (54%) pacientes os resultados da PCR e hemocultura foram concordantes. O coeficiente de concordância kappa obtido foi 0,147 (p = 0,131). Em relação ao sequenciamento, em 21 amostras de 16 pacientes foi possível identificar um agente etiológico. As bactérias mais detectadas foram Escherichia coli (3), Enterococcus sp. (2), Staphylococcus sp. (2) e Ralstonia sp. (2). Em apenas dois pacientes as amostras tiveram a mesma espécie bacteriana detectada na hemocultura e PCR de largo espectro (E. coli e Streptococcus pneumoniae). Em resumo, a PCR de largo espectro foi mais sensível do que a hemocultura na identificação bacteriana em pacientes com sepse atendidos em um Hospital de Emergência / Sepsis is responsible for a high rate of hospitalization and mortality. Due to the severity of clinical presentation and limitation of traditional methods for bacterial identification and isolation, it is recommended to initiate empirically broad-spectrum antimicrobial treatment. The development of molecular biology, particularly the polymerase chain reaction (PCR), enabled to realize a rapid diagnosis of infectious agents. However, due to the diversity of possible etiologic agents in sepsis, the use of PCR with specific primers for each agent becomes impractical. With the broad-range PCR, it is possible, in a single reaction, to identify any bacteria, allowing an early and directed treatment. Thus, this study aimed to evaluate the role of broad-range PCR in the etiologic diagnosis of patients with sepsis and compare this technique with traditional methods of culture. Seventy-four patients with sepsis admitted to the Emergency Unit of Clinical Hospital of Ribeirão Preto Medical School USP and 14 controls were included in the study. DNA from serum, plasma and buffy-coat were extracted from all patients and controls. Broad-range PCR was performed in all samples, followed by DNA sequencing of the amplicons. Out of 74 patients, 39 (53%) were male, mean age was 55 ± 19 years old; 37 (50%) patients had severe sepsis and 37 (50%) septic shock; the mortality rate was 51%. Most of primary infections were from respiratory tract (66%), followed by urinary tract infection (20%). Blood culture was positive in 22 (30%) patients, and its positivity was greater in older patients (p< 0,05) and patients with higher levels of C reactive protein (CRP) (p< 0,05). Broad-range PCR was positive in 44 (59%) patients, when considering both pairs of primers, and was significantly increased compared to blood culture positivity (p< 0,001). Broad-range PCR using Bak11W/Bak2 primers was positive in 25 (34%) patients, and using Taf/Tar primers, in 29 (39%) patients. Related to blood fractions, samples from 24 patients were positive in serum; 22 in plasma fraction; and 18 in buffy-coat. None of clinical and demographic characteristics influenced the broad-range PCR positivity. The sensitivity, specificity, positive predicted value and negative predictive value, when considered healthy persons as negative control, were 59%, 100%, 100% and 32%, respectively. In 40 (54%) patients, blood culture and PCR results were concordant. The concordance coefficient kappa obtained was 0,147 (p = 0,131). Regarding to etiologic agents, in 21 samples, from 16 patients, a bacteria was identified by sequencing. The most common bacteria were Escherichia coli (3), Enterococcus sp. (2), Staphylococcus sp. (2) and Ralstonia sp. (2). In only two patients, the same bacterial species were identified in both, blood culture and broad-range PCR (E. coli e Streptococcus pneumoniae). In conclusion, broad-range PCR was more sensitive than blood culture for bacterial identification in septic patients admitted to an Emergency Unit
25

Hunting Specialisation and the Broad Spectrum Revolution in the Early Epipalaeolithic: Gazelle Exploitation at Urkan e-Rubb IIa, Jordan Valley

Humphrey, Emma 22 August 2012 (has links)
This present research explores the impact of Flannery’s (1969) Broad Spectrum Revolution model within the context of the Levantine Epipalaeolithic, specifically the early (Kebaran) Epipalaeolithic. This model attempts to explain changes in subsistence behaviour associated with the end of the Pleistocene leading up to the development of agriculture. The Jordan valley represents an ideal model for Flannery’s marginal habitat because of the range of different flora and fauna required more intensive resource exploitation strategies. The discussion here focuses on the zooarchaeological and taphonomic analysis of two faunal assemblages (representing two sub-horizons) from Urkan e-Rubb IIa, a Kebaran site located in the lower Jordan Valley, and excavated by E. Hovers (Institute of Archaeology, Hebrew University Jerusalem), in 1986 and 1988. This site shows evidence of specialised gazelle hunting and processing. Initial interpretations of the site argued for a multi-purpose residential base camp, supported by lithic tool and shell bead manufacturing. Recent discussions of Epipalaeolithic diet breadth have concentrated on the end of the Pleistocene (Munro 2001, 2003, 2004, 2009; Stiner 2001; Stiner & Munro 2002; Stiner et al. 1999, 2000; Stutz et al. 2009) and have been directed towards explaining changing subsistence patterns towards the end of the Epipalaeolithic (i.e. the Natufian), where an increased use of wild cereals and small game has been well documented. The view that it is not until the Natufian that broad spectrum resource strategies were used is questioned here. Major questions that are addressed with this research include: What do the faunal assemblages from Urkan e-Rubb IIa tell us about Kebaran subisistence behaviour? Do broad spectrum models help to shed light on subsistence adaptations at the end of the Last Glacial Maximum? What can recent analyses of Jordan Valley faunal assemblages contribute to the discussion? These are addressed through a detailed zooarchaeological and taphonomic analysis of the Urkan e-Rubb IIa fauana, followed by synchronic and diachronic analyses of Levantine Epipalaeolithic assemblages, through a combination of taxonomy-based diversity indices and prey-ranking indices.
26

Hunting Specialisation and the Broad Spectrum Revolution in the Early Epipalaeolithic: Gazelle Exploitation at Urkan e-Rubb IIa, Jordan Valley

Humphrey, Emma 22 August 2012 (has links)
This present research explores the impact of Flannery’s (1969) Broad Spectrum Revolution model within the context of the Levantine Epipalaeolithic, specifically the early (Kebaran) Epipalaeolithic. This model attempts to explain changes in subsistence behaviour associated with the end of the Pleistocene leading up to the development of agriculture. The Jordan valley represents an ideal model for Flannery’s marginal habitat because of the range of different flora and fauna required more intensive resource exploitation strategies. The discussion here focuses on the zooarchaeological and taphonomic analysis of two faunal assemblages (representing two sub-horizons) from Urkan e-Rubb IIa, a Kebaran site located in the lower Jordan Valley, and excavated by E. Hovers (Institute of Archaeology, Hebrew University Jerusalem), in 1986 and 1988. This site shows evidence of specialised gazelle hunting and processing. Initial interpretations of the site argued for a multi-purpose residential base camp, supported by lithic tool and shell bead manufacturing. Recent discussions of Epipalaeolithic diet breadth have concentrated on the end of the Pleistocene (Munro 2001, 2003, 2004, 2009; Stiner 2001; Stiner & Munro 2002; Stiner et al. 1999, 2000; Stutz et al. 2009) and have been directed towards explaining changing subsistence patterns towards the end of the Epipalaeolithic (i.e. the Natufian), where an increased use of wild cereals and small game has been well documented. The view that it is not until the Natufian that broad spectrum resource strategies were used is questioned here. Major questions that are addressed with this research include: What do the faunal assemblages from Urkan e-Rubb IIa tell us about Kebaran subisistence behaviour? Do broad spectrum models help to shed light on subsistence adaptations at the end of the Last Glacial Maximum? What can recent analyses of Jordan Valley faunal assemblages contribute to the discussion? These are addressed through a detailed zooarchaeological and taphonomic analysis of the Urkan e-Rubb IIa fauana, followed by synchronic and diachronic analyses of Levantine Epipalaeolithic assemblages, through a combination of taxonomy-based diversity indices and prey-ranking indices.
27

An evaluation of grid based broad phase collision detection for real time interactive environments

Liljeby, Jonas January 2011 (has links)
Detailed and exact collision detection for large amounts of objects has for a long time been a non real-time affair because of the immense amount of computations necessary. This was however not only because of the complexity of the algorithms but also because discussed of the computations would not have had to be done in the first place. This paper has through literature research and empirical testing examined two different broad phase approaches to object culling in a three dimensional environment. The aim of such a broad phase algorithm is to decrease the amount of computation heavy narrow phase collision detection checks and thus enhancing application performance. Potential weaknesses of these approaches were addressed and possible solutions discussed. Performance comparisons were made to give a better overview of what kind of performance enhancements can be expected and to give a theoretical base for further research.
28

Comparison of saproxylic beetle assemblages on four different broad-leaved tree species in south-eastern Sweden

Johansson, Helena January 2011 (has links)
Old hollow trees have declined in Europe and many saproxylic (wood-dwelling) beetles dependent on them are threatened. Several studies have been done on old hollow oaks and they have been shown to harbour a species-rich saproxylic beetle fauna. However, other broad-leaved trees might also be important to consider as supporting habitats. The aim of this study was to investigate to what extent saproxylic beetles are tree genus specialists. Pitfall traps and window traps were used to compare the saproxylic beetle fauna in oak, ash, norway maple and small-leaved lime in an area dominated by old oaks. 5,501 specimens of saproxylic beetles were found, belonging to 239 species of which 27 species were red-listed. There were significant differences in the saproxylic species composition between the four tree species, but with large overlaps. The saproxylic species found in oak overlapped to 66 % with norway maple, to 67 % with ash and to 70 % with small-leaved lime. About one third of the species in this study seem to be tree genus specialists. The conclusion is that other broad-leaved trees are important to consider in models as supporting habitats for oaks. However, to be able to save the whole fauna of saproxylic beetles, trees of all different tree species are needed.
29

The study of the broad-leaved forest vegetation in the upper section of Pa-Chang River

Lin, Yi-ying 16 August 2004 (has links)
Pa-Chang River is in Southwestern Taiwan. It originates from Fenchihu, Alishan and flows between Chiayi County and Tainan County. Its total length is 81 kilometer and total basin area is 475 square kilometer. The natural forest communities are mostly in the upper section and fragmentarily spread in the small areas that locate between farms or in complicated topography, e.g. steep slope, area difficult to reach. It is necessary to make inventory and research about these natural forest communities now to gather sufficient vegetation data which will be served as basic reference in the future local environmental management. This study is to investigate and analyze the species composition of broad-leaved forest vegetation in the upper section of Pa-Chang River. The analysis results of the vegetation data by detrended correspondence analysis¡]DCA¡^ and two-way indicator species analysis¡]TWINSPAN¡^classified the sampling plots into four forest types: I. Litsea hypophaea forest type The range of elevation is 743~1003 m. The topographic position is mainly in ridge and upper slope. II. Ficus irisana -Dendrocnide meyeniana forest type The range of elevation is 381~825 m¡CThe topographic position is mainly in lower slope and valley. III. Machilus japonica var. kusanoi -Ficus fistulosa forest type The range of elevation is 764~1229 m¡C IV. Prunus phaeosticta forest type The range of elevation is 1559~1804 m. The topographic position is mainly in upper slope. The study of correlations among environmental gradients and ordination axes indicated that the elevation is the most important environmental factor affecting the vegetation composition and distribution. Topographic position also has obvious influence on vegetation. In addition, the study of population structure shows that regeneration is continuous in present broad-leaved forest, but the forest is also continuously disturbed by artificial activities. The area of natural forest in this area might continuously be decreased, so it is important to gather sufficient vegetation data in time.
30

Broad Complex Evolution, Function and Expression: Insights From Tissue Reorganization During Metamorphosis

Spokony, Rebecca Fran January 2007 (has links)
Broad Complex (BRC) is an ecdysone-pathway gene essential for entry into and progression through metamorphosis in D. melanogaster. Mutations of three BRC complementation groups cause numerous phenotypes, including a common suite of morphogenesis defects involving central nervous system (CNS), adult salivary glands (aSG), and male genitalia. Alternative splicing, of a protein-binding BTB-encoding exon (BTBBRC) to one of four tandemly duplicated, DNA-binding zinc-finger-encoding exons (Z1BRC, Z2BRC, Z3BRC, Z4BRC), produces four BRC isoforms. Highly conserved orthologs of BTBBRC and all four ZBRC were found in silico from Diptera, Lepidoptera, Hymenoptera and Coleoptera, indicating that BRC arose and underwent internal exon duplication before the split of holometalolous orders. Five Tramtrack subfamily members were characterized throughout Holometabola and used to root phylogenetic analyses of ZBRC exons, revealing that Z3BRC is the basal member. All four ZBRC domains, including Z4BRC which has no known essential function, are evolving in a manner consistent with selective constraint. Transgenic rescue and immunohistochemistry were used to explore how different BRC isoforms contribute to their shared tissue-morphogenesis functions at the onset of metamorphosis, when BRC is required for CNS reorganization. As predicted, the common CNS and aSG phenotypes were rescued by BRC-Z1 in rbp mutants, BRC-Z2 in br mutants, and BRC-Z3 in 2Bc mutants. However, the isoforms are required at two developmental stages, with BRC-Z2 and -Z3 required earlier than BRC-Z1. Each isoform had a unique expression pattern in the CNS, with no substantial three-way overlap among them. Z4 is strongly expressed in a novel subset of CNS neurons. The most prominent localizations of BRC-Z1, -Z2, -Z3 corresponded with glia, neuroblasts and neurons, respectively. There appears to be a switch from BRC-Z2 in proliferating cells to BRC-Z1 and BRC-Z3 in differentiating cells. The temporal-requirement and spatial-distribution data suggest that BRC-dependent CNS morphogenesis is the result of multicellular interactions among different cell types at different times. BRC-Z1-expressing glia in prepupae may mediate the final steps of CNS morphogenesis. Lastly, BRC is required for migration and programmed cell death of the ring gland, the site of ecdysone and juvenile hormone production. Therefore, BRC may function in ecdysone auto-regulation.

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