• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1946
  • 583
  • 219
  • 207
  • 182
  • 164
  • 70
  • 55
  • 49
  • 39
  • 38
  • 31
  • 19
  • 15
  • 12
  • Tagged with
  • 4441
  • 562
  • 460
  • 319
  • 316
  • 294
  • 287
  • 267
  • 204
  • 199
  • 199
  • 188
  • 179
  • 170
  • 169
  • 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.
691

Factors affecting overwinter mortality and early marine growth in the first ocean year of juvenile Chinook salmon in Quatsino Sound, British Columbia

Middleton, Katherine Rose 03 August 2011 (has links)
Evidence suggests that the variability in recruitment of adult Pacific salmon is related to smolt survival during the first ocean year. Specifically, the first few weeks and first marine winter may be two critical periods of high mortality during early marine life. Mortality during early marine residency has been attributed to predation and size-dependent factors while high mortality during the first winter may be due to energy deficits and failure to reach a certain size by the end of the growing season. My study assessed factors influencing overwinter mortality and early marine growth in juvenile Chinook salmon (Oncorhynchus tshawytscha) from Marble River, Quatsino Sound, British Columbia. Juvenile salmon were collected during November 2005 and 2006 (fall) and March 2006 and 2007(winter). Mortality rates over the first winter derived from catch per unit effort across seasons ranged between 80-90% in all years. These are the first estimations of overwinter mortality in juvenile Pacific salmon. Fish size distributions showed no evidence of size-selective overwinter mortality between fall and winter fish in either 2005-2006 or 2006-2007. Otolith microstructure analyses showed no significant difference in circulus increment widths during the first four weeks after marine entry. Similarities in increment width indicated that early marine growth did not differ between fall and winter fish during early marine residency in 2006. These observations show that the high overwinter mortality rates of juvenile Chinook salmon in Quatsino Sound are not size-dependent. Total plankton biomass was significantly lower in the winter season but size distribution, gut fullness and energy density data did not show evidence of starvation. No correlation was found between early marine growth, size, energy accumulation and high mortality in Marble River juvenile Chinook salmon during their first ocean winter in Quatsino Sound. Possible factors influencing these high mortality rates may include non size-selective predation, disease, local environmental influences or an as yet unknown source. Future work should continue to focus on understanding the relationship between early marine survival and adult recruitment. The expansion of growth comparisons geographically and chronologically while determining the effects of predatory mortality on juvenile Chinook salmon along the north Pacific continental shelf and beyond are imperative to fully understanding this complex marine life stage. / Graduate
692

Poly(A) Polymerase 1 (PAPS1) influences organ size and pathogen response in Arabidopsis thaliana

Trost, Gerda January 2014 (has links)
Polyadenylation of pre-mRNAs is critical for efficient nuclear export, stability, and translation of the mature mRNAs, and thus for gene expression. The bulk of pre-mRNAs are processed by canonical nuclear poly(A) polymerase (PAPS). Both vertebrate and higher-plant genomes encode more than one isoform of this enzyme, and these are coexpressed in different tissues. However, in neither case is it known whether the isoforms fulfill different functions or polyadenylate distinct subsets of pre-mRNAs. This thesis shows that the three canonical nuclear PAPS isoforms in Arabidopsis are functionally specialized owing to their evolutionarily divergent C-terminal domains. A moderate loss-of-function mutant in PAPS1 leads to increase in floral organ size, whereas leaf size is reduced. A strong loss-of-function mutation causes a male gametophytic defect, whereas a weak allele leads to reduced leaf growth. By contrast, plants lacking both PAPS2 and PAPS4 function are viable with wild-type leaf growth. Polyadenylation of SMALL AUXIN UP RNA (SAUR) mRNAs depends specifically on PAPS1 function. The resulting reduction in SAUR activity in paps1 mutants contributes to their reduced leaf growth, providing a causal link between polyadenylation of specific pre-mRNAs by a particular PAPS isoform and plant growth. Additionally, opposite effects of PAPS1 on leaf and flower growth reflect the different identities of these organs. The overgrowth of paps1 mutant petals is due to increased recruitment of founder cells into early organ primordia whereas the reduced leaf size is due to an ectopic pathogen response. This constitutive immune response leads to increased resistance to the biotrophic oomycete Hyaloperonospora arabidopsidis and reflects activation of the salicylic acid-independent signalling pathway downstream of ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1)/PHYTOALEXIN DEFICIENT4 (PAD4). Immune responses are accompanied by intracellular redox changes. Consistent with this, the redox-status of the chloroplast is altered in paps1-1 mutants. The molecular effects of the paps1-1 mutation were analysed using an RNA sequencing approach that distinguishes between long- and short tailed mRNA. The results shown here suggest the existence of an additional layer of regulation in plants and possibly vertebrate gene expression, whereby the relative activities of canonical nuclear PAPS isoforms control de novo synthesized poly(A) tail length and hence expression of specific subsets of mRNAs. / Polyadenylierung von prä-mRNAs ist entscheidend für den Export aus dem Zellkern, die Stabilität und die Translation der reifen mRNAs und dadurch für die Genexpression. Der Großteil der mRNAs wird durch sogenannte canonische Poly(A) Polymerasen (cPAPS) prozessiert. Die Genome von sowohl Wirbeltieren als auch Pflanzen kodieren mehr als eine Isoform dieser Enzyme, welche gleichzeitig in verschiedenen Geweben exprimiert werden. Es ist jedoch kein Beispiel bekannt, das zeigt, ob die verschiedenen Isoformen unterschiedliche Funktionen einnehmen bzw. verschiedene Untergruppen von mRNAs polyadenylieren. Diese Arbeit zeigt, dass drei canonische PAPS Isoformen in Arabidopsis thaliana aufgrund ihrer evolutionär unterschiedlichen C-terminalen Domänen spezialisierte Funktionen haben. Eine schwache Verlust-Mutation im PAPS1 Gen bewirkt eine Vergrößerung der Blütenorgane, während die Blattgröße vermindert ist. Eine starke Verlust-Mutation bewirkt zusätzlich einen Defekt der männlichen Keimzellen. Im Gegenzug dazu sind Mutanten des PAPS2 oder PAPS4 Gens gesund und zeigen ein normales Wachstum. Polyadenylierung von SMALL AUXIN UP RNA (SAUR) mRNAs hängt spezifisch von der Funktion von PAPS1 ab. Die daraus entstehende Reduzierung der SAUR Aktivität in den paps1 Mutanten trägt zur Verringerung der Blattgröße bei und stellt eine kausale Verbindung zwischen Polyadenylierung spezifischer mRNAs durch bestimmte PAPS Isoformen und Pflanzenwachstum dar. Zusätzlich spiegeln die unterschiedlichen Effekte von PAPS1 auf Blüten und Blätter die Identitäten dieser Organe wieder. Das übermäßige Wachstum der mutanten Petalen beruht auf einer erhöhten Anzahl an Gründer-Zellen im frühen Primordium, wohingegen die verminderte Blattgröße auf eine ektopische Pathogen Antwort zurückzuführen ist. Diese konstitutive Immunantwort bewirkt eine erhöhte Resistenz der Mutanten gegenüber dem biotrophen Oomyceten Hyaloperonospora arabidopsidis und reflektiert die Aktivierung des Salizylsäure unabhängigen Signalweges von ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1)/PHYTOALEXIN DEFICIENT4 (PAD4). Immunantworten sind von Veränderungen des intrazellulären Redoxpotenzials gekennzeichnet. Damit übereinstimmend zeigen die Chloroplasten der paps1-1 Mutanten ein verändertes Redoxpotenzial. Zur genaueren Aufklärung der molekularen Effekte der paps1 1 mutation wurde eine RNA-Sequenzierungsmethode verwendet, die zwischen mRNAs mit langem oder kurzem Poly(A) Schwanz unterscheidet. Die Aktivitäten der verschiedenen canonischen PAPS Isoformen kontrollieren die Länge des neu synthetisierten poly(A) Schwanzes und damit die Expression spezifischer Untergruppen von mRNAs. Dadurch lassen die hier gezeigten Ergebnisse eine weitere Ebene der Genregulierung in Pflanzen, und möglicherweise auch in anderen Eukaryoten, vermuten.
693

Feeding behaviour of Ateles belzebuth E. Geoffroy 1806 (Cebidae: Atelinae) in Tawadu Forest southern Venezuela

Amoroso, Castellanos Hernan Gerardo January 1995 (has links)
No description available.
694

Color Image Based Face Recognition

Ganapathi, Tejaswini 24 February 2009 (has links)
Traditional appearance based face recognition (FR) systems use gray scale images, however recently attention has been drawn to the use of color images. Color inputs have a larger dimensionality, which increases the computational cost, and makes the small sample size (SSS) problem in supervised FR systems more challenging. It is therefore important to determine the scenarios in which usage of color information helps the FR system. In this thesis, it was found that inclusion of chromatic information in FR systems is shown to be particularly advantageous in poor illumination conditions. In supervised systems, a color input of optimal dimensionality would improve the FR performance under SSS conditions. A fusion of decisions from individual spectral planes also helps in the SSS scenario. Finally, chromatic information is integrated into a supervised ensemble learner to address pose and illumination variations. This framework significantly boosts FR performance under a range of learning scenarios.
695

The Transformation Of The Religious Tradesmen In Small Cities In The Context Of Market Economy: The Case Of Kirikkale

Yildiz, Sitki 01 January 2003 (has links) (PDF)
Based on a field study carried out in Kirikkale, this study investigates the transformation of religious tradesmen of small cities in Turkey with emphases on : (a) the role of religious values within the free market economy / (b) the &amp / #65533 / work ethics&amp / #65533 / of religious tradesmen and (c) the transformation process of religious values within the present economic system. In the study, semistructured in-depth interviews and official documents were used to collect the research data. The thesis of Weber on the relationships between religious values and the rational capitalism was examined to better understand the work ethics and the religious values of religious tradesmen. The opinions of Weber, Rodinson and &Uuml / lgener about the causes of the nonexistence of a rational capitalism in the Islamic world were evaluated throughout the study. In this respect, the emergence and the development of the Muslim guilds and petty bourgeoisie within the traditional Islamic societies were also studied. The research results suggest that the incorporation into the free market economy brings about the transformation the religious economic convictions or values. Therefore, the chance of survival and the applicability of such religious values within this economic system seem to be impossible. In summary, this particular research indicates that the religious tradesmen do not face with serious contradictions in their economic activities. They rather seem to be involved in a transformation and adaptation process in the free market economy.
696

Modelling of Ore Floatability in Industrial Flotation Circuits

Kym Runge Unknown Date (has links)
Ore floatability is defined as the propensity of particles to float within a flotation environment and any effective mathematical model of the flotation process must incorporate its effect. The objective of this thesis was to review the ore floatability models in the literature and for those considered appropriate: • investigate their basic assumptions, • evaluate the type of experimental data required to derive model parameters, • and test their predictive capability. A review of the literature identified three different methods of representing ore floatability in flotation circuit models. Two approaches were studied within this thesis, namely the empirically derived floatability component model and the property based floatability component model. The third shaped distribution modelling approach was considered too inflexible a methodology to represent all types of ore floatability distributions. Ore floatability cannot be directly measured but must be inferred from a flotation response. In this thesis, it was investigated using batch laboratory flotation tests which, for a particular system, were all performed using the same set of operating conditions. Any difference in response between tests performed in this way was attributed to a change in ore floatability. Within this thesis, hundreds of batch laboratory flotation tests were performed using samples collected from the streams of seven different industrial flotation circuits. These tests, in combination with circuit survey data, were used to investigate various assumptions underpinning the ore floatability models. The tests also provide the experimental information required to derive the flotation properties of the two chosen ore floatability models. Both the two models investigated in this thesis assume the floatability of a particle in a flotation circuit to remain the same before and after processes in the circuit. A nodal analysis technique was developed by the author to compare the floatability in the feed and product of a flotation circuit process using batch laboratory flotation test information. This technique was used to show that ore floatability is a conserved property across most flotation, mixing and cycloning processes. In the cases where floatability was not conserved, it is suspected that the surfaces of the particles have changed due to oxidation, adsorption of hydrophilic species or decomposition of reagent surface species. Ore floatability was usually not conserved across processes which are designed to change particle properties (e.g. reagent addition and regrinding). An additional requirement of the ore floatability models is that all particles assigned to a particular component must float with a similar flotation rate. Sizing and liberation analysis of batch laboratory flotation test data showed that property based floatability component models based on size and liberation alone do not satisfy this criteria. It was concluded that a property based model would need to include information about the chemical state of the particle surfaces. As this type of measurement was considered beyond the scope of this thesis, no further analysis of this type of model was possible. Techniques for determining the empirically derived floatability component model parameters were studied using statistical techniques. This analysis showed that unique, stable parameters could be obtained by fitting the models to match multiple batch flotation test data collected at the same time as a circuit survey. It was found that a minimum of four batch laboratory flotation tests were required to derive statistically stable parameters. The use of one laboratory batch flotation test (the traditional method of parameter derivation) results in parameters which are highly sensitive to the error in the batch laboratory flotation test data. A methodology to simulate and predict ore grade and recovery in a flotation circuit based on different ore floatability particle groupings was developed by the author. A theoretical analysis was performed using this algorithm which showed that a two floating component and one non-floating component model produced similar predictions to a multi-component model developed using size and liberation information in a circuit subject to changes in cell operation, residence time and circuit configuration. It was therefore concluded that a discrete floatability component model has the ability to represent, what is in reality, a more complex particle floatability distribution. The analysis performed in this thesis shows that the empirically derived ore floatability component model is a valid method of representing ore floatability within a flotation circuit model which does not contain grinding or reagent addition processes. Parameters of the model can be derived with statistical confidence using multiple batch flotation test data. To effectively model ore floatability in circuits containing regrinding or staged reagent addition, ore floatability models need to be developed which incorporate parameters related to the physical properties of the ore. It is therefore recommended that research be performed to determine the effect of size, liberation and chemical conditioning on the ore floatability of a particle and how these effects are best incorporated into an ore floatability model.
697

The influence of education on the fertility transition in Sri Lanka / by Dissanayake Mudiyanselage Sri Shanthi Lakshman Dissanayake.

Dissanayake, Dissanayake Mudiyanselage Sri Shanthi Lakshman January 1995 (has links)
Bibliography: leaves 336-365. / xx, 365 leaves : ill., maps ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Geography, 1995
698

Modelling studies of the interaction between homogenisation, centrifugation and inclusion body dissolution / by Heng Ho Wong.

Wong, Heng Ho January 1997 (has links)
Bibliography: leaves 208-216. / xxii, 231 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The aim of this thesis is to define optimal centrifuge operating conditions for inclusion body recovery. Special attention is directed to the interaction of the recovery step with upstream and downstream processes. A new Eschenchia coli debris sizing method, Asoc, is developed to overcome the limitations of existing sizing methods. / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemical Engineering, 1997?
699

Physicochemical properties of protein inclusion bodies / by Norbertus Djajasantosa Wangsa-Wirawan.

Wangsa-Wirawan, Norbertus Djajasantosa January 1999 (has links)
Bibliography: leaves 182-198. / xv, 207 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Improvements in the current production system of inclusion bodies and the downstream processing sequence are essential to maintain a competitive advantage in the market place. Optimisation of fermentation is considered to improve production yield; then flotation as a possible inclusion body recovery method. / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemical Engineering, 2000?
700

The textural effects of multiphase mineral systems in liberation measurement

Latti, Anna Dewetia. Unknown Date (has links)
No description available.

Page generated in 0.0404 seconds