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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.
221

MAGNETIC PROPERTIES OF Nb/Ni SUPERCONDUCTING / FERROMAGNETIC MULTILAYERS

Kryukov, Sergiy A 01 January 2012 (has links)
Magnetic properties of Nb/Ni superconducting (SC) / ferromagnetic (FM) multilayers exhibit interesting properties near and below SC transition. A complex Field (H) – Temperature (T) phase boundary is observed in perpendicular and parallel orientation of ML with respect to DC field. We address the critical need to develop methods to make reliable magnetic measurements on SC thin films and ML, in spite of their extreme shape anisotropy and the strong diamagnetic response of the SC state. Abrupt, highly reproducible “switching” of the SC state magnetization near the normal-state FM coercive fields has been observed in Nb/Ni ML. The SC penetration depth l(Nb) > the SC coherence length xo(Nb) » 40 nm >> the FM layer thickness y(Ni) = 5 nm, abrupt magnetic reversals might be driven by strong supercurrent densities (J x M torques) that have the potential to flow into the Ni layers. Alternatively, sharp magnetization anomalies also can result from strong flux pinning by the periodic layered structure of ML, including “lock-in” of quantized flux lines (FL) parallel to the ML plane. Strong confinement of the supercurrents within ML planes might also lead to various phase transitions of the FL lattice (FLL) composed of one-dimensional chains and other unusual structures. Possible mechanisms for the switching anomalies must be evaluated while considering other experimental properties of Nb(x)/Ni(y) ML: 1) The upper critical magnetic field Hc2(T) exhibits a highly unusual anisotropy where the SC transition temperature Tc (H®0) for DC field H ^ ML plane exceeds the value for H || ML by ~ 0.5 K. 2) Nb/Ni ML samples do not consistently exhibit magnetic signatures for the onset of superconductivity, depending on the details of the sample mounting procedure and the AC or DC method used in SQUID magnetometry experiments. 3) Unusual “wiggles” or oscillations of order 10-30 mK were observed in Hc2(T) in AC SQUID experiments with H || ML and can be even larger (~0.16 K), depending upon the AC drive amplitude ho and frequency f .
222

L'intégration en classe ordinaire d'élèves présentant des troubles du comportement par le biais d'activités de tutorat par les pairs

Beaulac, Julie 07 1900 (has links) (PDF)
Plusieurs élèves présentant des troubles du comportement éprouvent des difficultés en lecture, particulièrement en compréhension. L'objectif de ce mémoire est d'évaluer l'efficacité d'activités de tutorat par les pairs utilisées lors de périodes de décloisonnement. Après une période de niveau de base (activités régulières d'enseignement), les activités de tutorat par les pairs ont été implantées dans une classe ordinaire en intégrant des élèves en troubles du comportement d'une classe spéciale. La compréhension en lecture a été évaluée de manière bi-mensuelle. Contrairement à ce qui était anticipé, nous n'avons pas constaté de meilleurs progrès chez les élèves suite à l'introduction des activités de tutorat par les pairs. Ces résultats sont attribués au fait que les élèves proviennent d'un milieu très défavorisé. Les activités de tutorat par les pairs apparaissent néanmoins appropriées pour le décloisonnement, à tout le moins sur le plan de la gestion. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Trouble de comportement, compréhension en lecture, défavorisation, tutorat par les pairs.
223

Generation of uncorrelated photon-pairs in optical fibres

Cohen, Offir January 2010 (has links)
Light, which is composed of discrete quanta, or photons, is one of the most fundamental concepts in physics. Being an elementary entity, the behaviour of photons is governed by the rules of quantum mechanics. The ability to create, manipulate and measure quantum states of light is not only useful in foundational tests of quantum theory, but also in a wide range of quantum technologies – which aim to utilize non-classical properties of quantum systems to perform tasks not possible with classical resources. Only recently has it been possible to control the properties of number states of light, which have a fixed photon-number. Two-photon states are central to testing fundamental physical theories (such as locality and reality) and the implementation of quantum information technologies. The versatility of photon-pair states is en- abled by the potential entanglement properties it can posses. Thus controlling the correlations between photons is crucial to both pure and applied physics. To produce a single photon, a photon-pair state can be used. Detection of one photon indicates its twin’s existence. Many applications, such as optical quantum computation, require pure indistinguishable single photons. Heralding single pho- tons from a photon-pair will, in general, produce single photons in a mixed quantum state due to correlations within the pair. A common approach to creating photon-pairs is through the nonlinear sponta- neous four-wave mixing interaction in optical fibres. This thesis presents a theoreti- cal and experimental implementation of a scheme to tailor the spectral correlations within the pairs. Emphasis is placed on engineering the two-photon state such that they are completely uncorrelated. Spatial entanglement is naturally avoided due to the discrete nature of the optical fibre modes. Spectral correlations are eliminated by careful choice of dispersion characteristics and conditions. The purity of the photons generated by this scheme is demonstrated by means of two-photon inter- ference from independent sources. We measure a purity of (85.9 ± 1.6)% with no spectral filtering, exhibiting the usefulness of this source for quantum technologies and applications.
224

Gene-pair based statistical methods for testing gene set enrichment in microarray gene expression studies

Zhao, Kaiqiong 16 September 2016 (has links)
Gene set enrichment analysis aims to discover sets of genes, such as biological pathways or protein complexes, which may show moderate but coordinated differentiation across experimental conditions. The existing gene set enrichment approaches utilize single gene statistic as a measure of differentiation for individual genes. These approaches do not utilize any inter-gene correlations, but it has been known that genes in a pathway often interact with each other. Motivated by the need for taking gene dependence into account, we propose a novel gene set enrichment algorithm, where the gene-gene correlation is addressed via a gene-pair representation strategy. Relying on an appropriately defined gene pair statistic, the gene set statistic is formulated using a competitive null hypothesis. Extensive simulation studies show that our proposed approach can correctly control the type I error (false positive rate), and retain good statistical power for detecting true differential expression. The new method is also applied to analyze several gene expression datasets. / October 2016
225

An investigation into bilateral asymmetry of the appendicular skeleton of the adult human and its use in physical and forensic anthropology

Garrido Varas, Claudia E. January 2013 (has links)
The aim of this study was to establish whether the asymmetry of bilateral elements of the skeleton is useful for the reassociation of paired elements in the analysis of commingled skeletal remains; particularly addressing the forensic scenario of Chilean Human Rights cases. The asymmetry of the appendicular skeleton of the modern adult Chilean population was investigated in its morphological aspect, using both traditional anthropometry and geometric morphometrics. The sample was selected from the Colección Subactual de Santiago, housed in the University of Chile, Santiago, Chile, with N= 131 (69 males and 62 females). The traditional metric analysis of size and the geometric morphometric analysis of shape showed that there was a significant difference between sides in both sexes with a strong component of directional asymmetry. Mean metrics and ranges of asymmetry were established, contributing to the characterization of this population. A method to pair match elements from commingled settings, which is a combination of metric ranges of asymmetry and principal component analysis of shape variables, was created resulting in 95% accuracy when pair matching the humerus, radius, femur and tibia. This constitutes an important contribution to the analysis of shape in forensic contexts due to its strong mathematical component, objectivity and repeatability.
226

Elastomultibody dynamics of RWD axle whine phenomena

Koronias, George January 2012 (has links)
Automotive industry is faced with numerous power train Noise, Vibration and Harshness issues. Particularly, in the driveline area of vehicles a noise commonly referred as differential axle whine which is a tonal response and becomes apparent under cruising conditions. This is one of the key concerns in rear wheel drive commercial vehicles. Although not a failure state, it is regarded as a quality issue and a source of annoyance, which can lead to warranty concerns. The associated cost of palliation to Ford Motor Company was estimated to be $25,000,000 in 2003. There have been several ways of studying axle whine through experimentation and numerical analysis. In this thesis, a new approach for investigating axle whine is highlighted, which is more integrative and detailed. Multi-body dynamics model of a light truck s driveline is developed with all the appropriate components, using constrained Lagrangian dynamics. Component flexibility is included for driveshaft pieces, rear axle half-shafts and the suspension elements. The connectivity of the components is accurately modelled such as the floating effect of rear half-shafts, linear bushings between driveline components to chassis connections, as well as the non-linear effect of tapered roller bearings, supporting the wheel hubs and gears. Furthermore, integrated to the previously described large scale model a detailed hypoid gear pair model is devised. This incorporates micro-scale physics for tooth contact analysis to predict geometric properties and deflections for the gear pair. At the same time thermo-elastohydrodynamic lubrication theory with non-Newtonian friction is applied. All these phenomena at different physical scales, such as large displacement rigid body dynamics and analytical equations for the detailed model are solved simultaneously, all within the same modelling environment. This multi-physics, multi-scale approach has not hitherto been reported in the literature, and constitutes a significant contribution to knowledge. Comparative studies of the model predictions and detailed vehicle tests are carried out, the combination of which points to resonant conditions in system responses and flexible component behaviour, coincident with the adverse conditions in the hypoid gear meshing. It is shown that vehicle drive and coast conditions, promoting teeth pair separations lead to irregular (improper) meshing of the differential gears. Such conditions induce impulsive actions that promote the axle whine phenomenon. This is a major finding of the research and contributes to a better understanding of the axle whine problem.
227

Who's Your Daddy? A Study of Extra-Pair Copulation and Mating Behaviors of Protonotaria citrea

Heidrich, Morton Catherine 06 December 2013 (has links)
Mating behavior has a profound impact on reproductive success and the resulting genetic structure of offspring. Extra-pair copulation is a widely observed behavior within avian species. This study explored the genetic effects of mating behaviors of Prothonotary warblers, Protonotaria citrea (Parulidae), using co-dominant microsatellite markers. Prothonotary warblers are migratory songbirds that build nests in cavities, commonly found in wetland habitats. A set of artificial nest boxes were initiated by Dr Robert Reilly in 2002 in Dutch Gap, Chesterfield County Virginia, USA, a tidal tributary off the James River. From this population, 28 nest boxes were surveyed yielding 47 adults and 110 offspring. All individuals were genotyped and the multilocus genotypes were used to identify parentage. Using paternity exclusion, 27.2% of offspring were identified as resulting from extra-pair mating. Surprisingly, an additional 11.8% of offspring were classified as genetically unrelated to the resident female, being presumably the result of an egg dumping from a female not caught at the nest box. The vast majority of nest boxes, 82.1% in this study, had at least one offspring that was a result of a mating behavior outside of the social pair. There was also positive spatial autocorrelation in extra-pair paternity suggesting that these matings are not randomly distributed across the sampling landscape. These data show that Protonotaria citrea engage in both extra-pair copulations and nest parasitism. Whether this is normal mating behavior for the species, or something that is unique to this population is unknown.
228

Využití vysoce účinné iontové chromatografie ve farmaceutické analýze organických aniontů a kationtů / Pharmaceutical application of high performance ion chromatography in analysis of organic anions and cations

Čujová, Sabína January 2010 (has links)
The thesis is focused on application of ion chromatography in pharmaceutical analyses of organic ions. Ion chromatography is increasingly used in the field of pharmaceutical analysis. This includes the analysis of impurities and metabolites. In the first part of this thesis, ion chromatography is compared with common separation techniques used in pharmacy, such as gas chromatography and high performance liquid chromatography. In the second part development and validation of methods of ion chromatography for purity evaluation and quality control of active pharmaceutical substances Rivastigmine hemitartrate and Pramipexole hydrochloride were carried out. Key words: ion chromatography, reversed-phase chromatography, ion-pair chromatography, ion-exclusion chromatography, ion-exchange chromatography, GC, HPLC
229

Zlaté fólie z Borqu - ikonografická a náboženská analýza / Golden foils from Borg - iconographical and religious analysis

Gorroňová, Marianna January 2011 (has links)
5A Abstract This work gives the analysis of iconographic elements which are found on five gold foils. These foils depict two figures which look at each other from their profile. Foils were found in the foundations of the chieftain house in Lofot's islands in Northern Norway, which is from the Migration to the Viking period. For the reason of analysis the author demonstrates three main groups of gold objects - gold bracteates, gold foils and one medallion. On these objects we can find a pair of two figures and these objects were found in Scandinavia. The author presents here the context of such finds, iconographic elements and academic interpretations of the depiction. Author compares the elements such as type of foil, appearance of eyes, posture of man and woman, their dress and haidress with 91 foils from Scandinavia, and also with bracteates and other objects. She notices the partial concordance among these elements and the other objects and she seeks the iconographic essence and function of each foil from Borg which is later confronted with the theories of the influence of religion. Because of lack of attributes on the foils, the author's assumption is that there is no general depiction of gods on the foil. On the other hand, each foil has its own story showing people from their common life. According to...
230

Analýza různých technologií odchovu telat

HAMPLOVÁ, Michaela January 2019 (has links)
In cattle breeding, it is necessary to pay great attention to calves, especially to the quality of their housing. Calf rearing is one of the riskiest parts of the whole breed. This requires a thorough development of biological, nutritional, ethological and technological factors of breeding. The aim of this thesis was to compare two different ways of housing calves (individually vs. pairs) in roofed outdoor individual boxes with feedeng twice a day and evaluate their influence on the course of growth and health from birth to weaning. The experiment was carried out at the Číčov farm, which i sone of the centers of Alimex a.s. Nezvěstice, farming in the district of Plzeň - South. The actual monitoring of the calves took place from 1. 1. 2018 to 31. 7. 2018. Both groups of calves included in the experiment were fed the same amount of feed (native milk, milk replacer, TMR). Each group had the same number of pieces - 12 calves (heifers) of the Holstein cattle breed. At the end of the reporting period, calves that were raised together in pairs at average weight of 227.17 kg during the dairy period, while calves reared individually during the same period reached a final weight of 215 kg. The average daily increase in calves with a common rearing was 0.89 kg, in calves of the second group this value was lower, namely 0.83 kg. However, tthe difference between the mean final weights of both groups was not statistically significant (p > 0.05). All calves included tn the exxperiment were fed with appropriate quality colostrum (immunoglobulin content of 100 g/l or more) within 2 hours of delivery. Immunity of all experimental calves was sufficient, so the level of immunoglobulins did not fall below 50 g/l, with more than 85 % of calves having an immunoglobulin content above 55 g/l. In calves reared individually during the experiment, diarrhea was noted in three animals and respiratory disease in four animals. In rearing together, there was diarrhea in five calves. Respiratory disease occured in four calves. In both experimental groups of calves, it was observed that immediately after drinking, the animals were mutually sucking mules, but the calves housed together with a lower frequency also licked the polypropylene plates separating the VIB and nibbled empty buckets.

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