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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.
281

Distributional Characteristics of Lianas: Example of Hedera helix, Drayton Wood, Norwich.

Mercer, Theresa 01 1900 (has links)
The principal objective of this project was to determine whether Hedera helix was distributed randomly or exhibited host preferences within Drayton Wood, Norwich. 200 random tree samples >10cm diameter were studied. Of these, the CBH (circumference breast height), bark texture, abundance of H. helix and growth form were recorded. The percentage of ground covered by H. helix around the base of the sample trees was also recorded. Finally, the distance of the sample trees from the outer reaches of the wood and canopy cover were measured.Hedera helix was not distributed over potential host trees homogenously, but exhibited host associations. Quercus robur, Crataegus monogyna and Pinus sylvestris tree species were found to have a higher abundance of H. helix than expected by chance, whereas Acer pseudoplatanus and Betula pendula were found to have less H. helix vines than expected. Furthermore juvenile and mature vines were not distributed equally. Acer pseudoplatanus hosted more juveniles and less adults than expected, whereas Quercus robur and Pinus sylvestris hosted less juveniles and more mature vines than expected. Vines were not distributed independently of host size. Those trees <100cm CBH had a lesser stem abundance than expected, whereas those vines >100cm CBH had a greater stem abundance than expected. Host preference was exhibited for those large CBH trees with rough bark as opposed to large CBH trees with smooth bark. There was a higher abundance of H. helix (ground and trunk cover) with distance from the edge. Ground cover was greater under those trees hosting H. helix than those not supporting H. helix.Light did not play a major role in the distribution and abundance of H. helix (ground cover and trunk cover).Key Words: host selectivity, host size, bark texture, ground cover, location, light.
282

Hydrogen selective properties of cesium-hydrogensulphate membranes

Meyer, Faiek January 2006 (has links)
>Magister Scientiae - MSc / The production procedure of a CsHS04-Si02 composite membrane was optimized in order to obtain the highest possible H2:C02 and H2:C~ Idea selectivity permeance. The optimized membrane preparation procedure led to the preparation of membranes with Idea selectivity of 5 and 10 towards H2:C~ and H2:C02 respectively. The H2 permeance value is on average 0.15 umol- s-l·m-2.Pa-I. The reproducibility of the optimized membrane was further investigated and was found to be satisfactory. An attempt was made to discover the gas transport mechanism of H2, C~ and C02. Gas permeance measurements were carried out as a function of time and temperature (between 25-180°C) using H2, C~ and C02 as analyte gases. XRD, TGA and impedance spectroscopy were used to identify the phases of CsHS04 within the membrane. The gas permeation mechanism was found to be a combination of Knudsen diffusion and solution diffusion. The pores that allow Knudsen diffusion (allow transport of Hi, CH4 and C02) are believed to be located at the CSHS04 crystal phase boundaries. In parallel, H2 diffuses selectively through the lattice of phase II/III of CsHS04 ..
283

Cyclical Variations in Object and Spatial-based Attention

Unknown Date (has links)
Spatial-based attention is shown to vary in strength over short intervals of time. Whether object-based selection also has similar temporal variability is not known. Egly, Driver and Rafal (1994) demonstrated using 2-rectangle displays how both spatial and object-based selection engages in processing of a visual scene. In Experiment-1 using the 2-rectangle paradigm we measured temporal variability of target detection by presenting targets at a variable SOA. In Experiment-2, we used 4-squares to preclude any object-based selection and measured temporal variability in target detection at similar locations as in Experiment-1. We found target detection to be periodic in delta and theta hertz rhythm in both Experiment-1 and Experiment-2 upon comparing corresponding cue-valid and same-object locations. Similar spectral profiles across experiments indicate a split-spotlight of spatial attention that rhythmically monitors cue-valid and other invalid locations. Future experiments are needed to determine whether object-based selection is periodic in nature. / Includes bibliography. / Thesis (M.A.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection
284

Développement et application d’une approche de docking par fragments pour modéliser les interactions entre protéines et ARN simple-brin / Development and application of a fragment-based docking approach to model protein-ssRNA interactions

Chevrollier, Nicolas 09 May 2019 (has links)
Les interactions ARN-protéine interviennent dans de nombreux processus cellulaires fondamentaux. L'obtention de détails à l'échelle atomique de ces interactions nous éclaire sur leurs fonctions, mais permet également d'envisager la conception rationnelle de ligands pouvant les moduler. Lorsque les deux techniques majeures que sont la RMN et la cristallographie aux rayons X ne permettent pas d'obtenir une structure 3D entre les deux partenaires, des approches de docking peuvent être utilisées pour apporter des modèles. L'application de ces approches aux complexes ARN-protéine se heurtent cependant à une difficulté. Ces complexes résultent en effet souvent de la liaison spécifique d'une courte séquence d'ARN simple-brin (ARNsb) à sa protéine cible. Hors, la flexibilité inhérente aux segments simples-brins impose dans une approche classique de docking d'explorer un large ensemble de leur espace conformationnel. L'objectif du projet est de contourner cette difficulté par le développement d'une approche de docking dite "par fragments". Ce dernier s'est fait à partir de domaines de liaison à l'ARN très représentés dans le monde du vivant. Les résultats ont montré une excellente capacité prédictive de l'approche à partir de la séquence de l'ARN. Ils ont de plus montré un potentiel intéressant dans la prédiction de séquences d'ARN simple-brin préférentiellement reconnues par des domaines de liaisons à l'ARN. / RNA-protein interactions mediate numerous fundamental cellular processes. Atomic scale details of these interactions shed light on their functions but can also allow the rational design of ligands that could modulate them. NMR and X-ray crystallography are the 2 main techniques used to resolve 3D highresolution structures between two interacting molecules. Docking approaches can also be utilized to give models as an alternative. However, the application of these approaches to RNA-protein complexes is hampered by an issue. RNA-protein interactions often relies on the specific recognition of a short singlestranded RNA (ssRNA) sequence by the protein. The inherent flexibility of the ssRNA segment would impose, in a classical docking approach, to explore their resulting large conformation space which is not computationally reliable. The goal of this project is to overcome this barrier by using a fragment-based docking approach. This approach developed from some of the most represented RNA-binding domains showed excellent results in the prediction of the ssRNA-protein binding mode from the RNA sequence and also a great potential to predict preferential RNA binding sequences.
285

Self-interference Handling in OFDM Based Wireless Communication Systems

Yücek, Tevfik 14 November 2003 (has links)
Orthogonal Frequency Division Multiplexing (OFDM) is a multi-carrier modulation scheme that provides efficient bandwidth utilization and robustness against time dispersive channels. This thesis deals with self-interference, or the corruption of desired signal by itself, in OFDM systems. Inter-symbol Interference (ISI) and Inter-carrier Interference (ICI) are two types of self-interference in OFDM systems. Cyclic prefix is one method to prevent the ISI which is the interference of the echoes of a transmitted signal with the original transmitted signal. The length of cyclic prefix required to remove ISI depends on the channel conditions, and usually it is chosen according to the worst case channel scenario. Methods to find the required parameters to adapt the length of the cyclic prefix to the instantaneous channel conditions are investigated. Frequency selectivity of the channel is extracted from the instantaneous channel frequency estimates and methods to estimate related parameters, e.g. coherence bandwidth and Root-mean-squared (RMS) delay spread, are given. These parameters can also be used to better utilize the available resources in wireless systems through transmitter and receiver adaptation. Another common self-interference in OFDM systems is the ICI which is the power leakage among different sub-carriers that degrades the performance of both symbol detection and channel estimation. Two new methods are proposed to reduce the effect of ICI in symbol detection and in channel estimation. The first method uses the colored nature of ICI to cancel it in order to decrease the error rate in the detection of transmitted symbols, and the second method reduces the effect of ICI in channel estimation by jointly estimating the channel and frequency offset, a major source of ICI.
286

A Biologically Plausible Learning Rule for the Infomax on Recurrent Neural Networks. / 生物学的に想定しうるリカレント結合神経回路上の情報量最大化学習則

Hayakawa, Takashi 23 March 2015 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第18874号 / 医博第3985号 / 新制||医||1008(附属図書館) / 31825 / 京都大学大学院医学研究科医学専攻 / (主査)教授 渡邉 大, 教授 山田 亮, 教授 福山 秀直 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM
287

Studies on Site-selective C-H Alkylation of Arenes with Alkenes / アレーンのアルケンによるサイト選択的C-Hアルキル化に関する研究

Okumura, Shogo 25 March 2019 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21776号 / 工博第4593号 / 新制||工||1716(附属図書館) / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 中尾 佳亮, 教授 松原 誠二郎, 教授 杉野目 道紀 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
288

AROUSAL OR RELEVANCE? APPLYING A DISCRETE EMOTION PERSPECTIVE TO AGING AND AFFECT REGULATION

Lautzenhiser, Sara E. 20 June 2019 (has links)
No description available.
289

Speech-Language Pathologists’ Perceptions on Social Relationships of Older Adults with Aphasia Before and After Exposure to Socioemotional Selectivity Theory

Dinh, An January 2019 (has links)
No description available.
290

Novel Reactive Oxygen Species Activated Scaffold from Mechanism to Application

Zhu, Haizhou January 2019 (has links)
No description available.

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