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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.
91

Uncertainty Models For Vector Based Functional Curves And Assessing The Reliability Of G-band

Kurtar, Ahmet Kursat 01 December 2006 (has links) (PDF)
This study is about uncertainty medelling for vector features in geographic information systems (GIS). It has mainly two objectives which are about the band models used for uncertainty modelling . The first one is the assessment of accuracy of GBand model, which is the latest and the most complex uncertainty handling model for vector features. Some simulations and tests are applied to test the reliability of accuracy of G-Band with comparing Chrisman&rsquo / s epsilon band model, which is the most frequently used band model among the others. The tests are realized with two cases, testing with digitized lines by people and testing with randomly created lines with gaussian random number generator algorithm. So, the results can be examined in two different ways. The second aim of this thesis is development of band models for functional special curves. These functional curves are based on some mathematical models. Specifications of these curves are defined in the structure of Geographic Markup Language (GML) of Open GIS Consortium (OGC). They are arc, arc string, clothoid and cubic spline. Uncertainty for arc by three coordinates, arc string and cubic spline are modelled by G-Band. Arc by center point and clothoid are modelled by epsilon band. In this thesis, a commercial GIS API, GeoKIT is used to create the band geometries of functional curves, to perform some simulations and tests to make the comparison and to present the developed functionality as a desktop application. Band geomeiv tries are developed in the structure of API model which enable the functionality. Secondly, Matlab 2006a is used for technical computing to calculate multivariate normal cumulative density function (mvncdf) to be used in analyses and simulations.
92

Preparation And Characterization Of Biodegradable Composite Systems As Hard Tissue Supports: Bone Fillers, Bone Regeneration Membranes And Scaffolds

Aydemir Sezer, Umran 01 February 2012 (has links) (PDF)
In tissue engineering applications, use of biodegradable and biocompatible materials are essential. As the tissue regenerate itself on the material surface, the material degrades with enzymatic or hydrolytic reactions. After a certain time, natural tissue takes the place of the artificial support. Poly(&epsilon / -caprolactone) (PCL) is one of the preferable polymers used in the restoration of the bone defects due to its desirable mechanical properties and biocompatibility. Addition of inorganic calcium phosphate particles in PCL structures can improve the mechanical properties as well as osteoconductivity / and presence of an antibiotic can prevent infection that may occur at the defect site. In this study, three forms of biodegradable hard tissue supports which are bone fillers, bone regenerative membranes and 3D scaffolds were designed and prepared. As biodegradable bone fillers, composite microspheres containing gelatin and &beta / -tricalcium phosphate (&beta / -TCP) were prepared and characterized. Synthesized &beta / -TCP particles were coated with gelatin at different weight ratios and the effects of &beta / -TCP/Gelatin ratio on the morphology of the microspheres were evaluated. Also, a model antibiotic, gentamicin, was loaded to these microspheres and release behaviours of the drug and its antibacterial effect on E.Coli was determined. The selected composition of these microspherical bone fillers were used as additives in the preparation of bone regenerative membranes and scaffolds. For this purpose, microspheres were added into PCL solution and processed by either solvent casting or freeze-drying in order to prepare bone regenerative membranes or scaffolds, respectively. For every material, the ratio of constituents (microsphere and PCL) was altered in order to obtain optimum properties in the resulted hard tissue support structure. The effects of the ratio of the microspheres to PCL in terms of morphological, mechanical and degradation properties of composite films, as well as in vitro antibiotic release and antibacterial activities against E.Coli and S.Aureus were investigated. For scaffolds, the effects of the ratio of the microspheres to PCL on the morphological, mechanical, pore size distribution, degradation properties and in vitro antibiotic release were examined.
93

Redistribution of PKC{epsilon} to the Mitochondria: Comparing Myocardial Ischemic and Pharmacologic Preconditioning

Habbous, Steven 31 December 2010 (has links)
PKCe plays a very important role in mediating the protection against myocardial ischemia and reperfusion injury induced by ischemic preconditioning (IPC) and pharmacologic preconditioning (PPC). The redistribution of PKCe was assessed by subcellular fractionation and western blotting in the Langendorff-perfused rabbit heart. Either 5min ischemia or 5min administration of adenosine A1 and/or A3 agonists, bradykinin, angiotensin II, and d1-opioid agonists resulted in PKCe redistribution from the cytosol to the mitochondria. This effect of IPC on PKCe redistribution was visible up to at least 30min of reperfusion, while that of PPC was lost by 10min of drug washout, indicative of the transient nature of PKCe redistribution. PKCe redistribution to mitochondria by IPC was also visualized using immunogold electron microscopy. Thus, IPC and PPC caused PKCe redistribution from the cytosol to the mitochondria, which was longer-lasting in IPC than in PPC.
94

Redistribution of PKC{epsilon} to the Mitochondria: Comparing Myocardial Ischemic and Pharmacologic Preconditioning

Habbous, Steven 31 December 2010 (has links)
PKCe plays a very important role in mediating the protection against myocardial ischemia and reperfusion injury induced by ischemic preconditioning (IPC) and pharmacologic preconditioning (PPC). The redistribution of PKCe was assessed by subcellular fractionation and western blotting in the Langendorff-perfused rabbit heart. Either 5min ischemia or 5min administration of adenosine A1 and/or A3 agonists, bradykinin, angiotensin II, and d1-opioid agonists resulted in PKCe redistribution from the cytosol to the mitochondria. This effect of IPC on PKCe redistribution was visible up to at least 30min of reperfusion, while that of PPC was lost by 10min of drug washout, indicative of the transient nature of PKCe redistribution. PKCe redistribution to mitochondria by IPC was also visualized using immunogold electron microscopy. Thus, IPC and PPC caused PKCe redistribution from the cytosol to the mitochondria, which was longer-lasting in IPC than in PPC.
95

Stochastische Charakteristiken von Lösungen parabolischer Randanfangswertprobleme mit zufälligen Koeffizienten

Hähnel, Holger 06 May 2010 (has links) (PDF)
Im Mittelpunkt dieser Arbeit steht die Untersuchung des stochastischen Verhaltens von Lösungen parabolischer Randanfangswertprobleme mit zufälligen Koeffizienten. Aufgaben dieser Art entstehen beispielsweise bei der mathematischen Modellierung von Wärmeleitprozessen in Materialien, deren Wärmeleitfähigkeit als zufällige Größe bzw. als zufällige Funktion angesehen werden kann. Die Modellierung dieser stochastischen Einflüsse erfolgt u. a. mit Hilfe von epsilon-korrelierten Funktionen. Um stochastische Charakteristiken wie Erwartungswert-, Korrelations- und Varianzfunktion der Lösung des Randanfangswertproblems näherungsweise zu ermitteln, werden die Ansätze der Finite-Elemente-Methode (FEM), der Fouriermethode sowie der Stochastischen Simulation gewählt. Die beiden erstgenannten Verfahren erfahren eine Kombination mit der Methode der Störungsrechnung, wodurch sich jeweils Entwicklungen der gesuchten Charakteristiken bis zur zweiten Ordnung bezüglich eines Störungsparameters ergeben. Konkrete Ergebnisse werden für einfache ein- und zweidimensionale Gebiete ermittelt. Die Anwendung der Störungsrechnung wird im Fall der FEM zudem analytisch gerechtfertigt. Die Methode der Stochastischen Simulation nutzt die Approximation der eingehenden zufälligen Funktion durch Moving-Average-Felder. Für die Auswertung der auftretenden Integrale bei Anwendung der FEM werden explizite Formeln angegeben. Für einige Beispiele im ein- und zweidimensionalen Fall erfolgt die numerische Umsetzung sowie die grafische Präsentation der Ergebnisse sowie deren Vergleich für die verschiedenen eingesetzten Methoden. / This work focuses on the stochastic behavior of solutions of parabolic initial value problems with random coefficients. This sort of tasks is a result of modeling heat conduction processes on material whose heat conductivity can be considered as a random value or a random function. Stochastic influences are modeled, among others, by epsilon correlated functions. In order to determine stochastic characteristics like expectation value function, correlation function, and variance function of the problems solution approximately, the finite element method (FEM), the Fourier method, and the Monte Carlo Simulation are chosen. The first two methods are combined with perturbation techniques. This leads to expansions of the characteristics up to the second order with respect to a perturbation parameter. Results are determined for cases of one and two dimensional domains. The applicability of perturbation methods is verified for the FEM-based solution. The Monte Carlo Simulation uses the approximation of random functions by moving average fields. Explicit formulas are given for the evaluation of integrals which appear by applying the FEM. The work ends with the presenting of numerical examples for the one and two dimensional case.
96

Initial characterization and determination of the molecular mechanism(s) that control transcription of the human PKC epsilon gene in lung cancer cells

Akinyi, Linnet. January 2004 (has links)
Thesis (M.S.)--University of Florida, 2004. / Typescript. Title from title page of source document. Document formatted into pages; contains 52 pages. Includes Vita. Includes bibliographical references.
97

Αριθμητική προσομοίωση τυρβώδους ροής σε δεξαμενή άντλησης θαλασσίου ύδατος ψύξης

Ντζάνης, Ευστάθιος 24 October 2012 (has links)
Η χρήση θαλασσίου ύδατος για ψύξη μηχανών σε βιομηχανικές εγκαταστάσεις και σταθμούς παραγωγής ηλεκτρικής ενέργειας επιτυγχάνεται μέσω εγκαταστάσεων άντλησης θαλασσίου ύδατος. Οι δεξαμενές αυτών των εγκαταστάσεων πρέπει να σχεδιάζονται σύμφωνα με τις οδηγίες του Hydraulic Institute (1998) ώστε να αποφεύγονται ανεπιθύμητα φαινόμενα που επηρεάζουν την απόδοση και τη διάρκεια ζωής των αντλιών. Τέτοια φαινόμενα είναι οι στρόβιλοι, υποβρύχιοι και ελεύθερης επιφάνειας, η υπερβολική προ-ελίκωση της ροής ανάντη κάθε αντλίας, η ανομοιομορφία της ροής στην πτερωτή κάθε αντλίας, οι υπερβολικές χρονικές διακυμάνσεις της ταχύτητας και της ελίκωσης και η συμπαράσυρση αέρα και η δημιουργία φυσαλίδων. Στην παρούσα διατριβή εξετάζεται η δεξαμενή της εγκατάστασης άντλησης θαλασσίου ύδατος μέσω δύο αντλιών που βρίσκεται στον υπό κατασκευή Θερμοηλεκτρικό Σταθμό Φυσικού Αερίου της Δ.Ε.Η. στο Αλιβέρι. Σκοπός της διατριβής είναι η μελέτη της ροής στη συγκεκριμένη δεξαμενή ως προς την κυκλοφορία του ύδατος (γραμμές ροής και τύρβη), τις διατμητικές τάσεις στα τοιχώματα των αγωγών και της δεξαμενής, την προ-ελίκωση της ροής που προσεγγίζει την αντλία και την ανομοιομορφία της στο επίπεδο της πτερωτής της αντλίας, καθώς και η συμπεριφορά της ελίκωσης της ροής στους αγωγούς άντλησης. Η διερεύνηση της ροής γίνεται για αρκετές καταστάσεις λειτουργίας της δεξαμενής ως προς το βάθος ύδατος και τον αριθμό θυροφραγμάτων και αντλιών. Η γεωμετρία του υπολογιστικού πεδίου, το υβριδικό μη-δομημένο πλέγμα και η αριθμητική επίλυση των εξισώσεων ροής πραγματοποιήθηκαν με τα προγράμματα Design Modeler, Meshing και Fluent του ANSYS. Ειδικότερα για το Fluent επιλέχθηκαν τα μοντέλα τύρβης k-ε και k-ω. Τα αποτελέσματα αναλύονται και συγκρίνονται με τα πειραματικά του υδραυλικού μοντέλου (Dimas & Vouros, 2012) σε κλίμακα 1:8.7 κατά Froude. Στις περιπτώσεις όπου είναι ανοικτό μόνο το ένα θυρόφραγμα, έχουμε κυκλοφορία της ροής μεταξύ των δύο θαλάμων των αντλιών κυρίως κοντά στην ελεύθερη επιφάνεια του ύδατος. Στις περιπτώσεις όπου λειτουργεί μόνο η μία αντλία, έχουμε και έντονη κυκλοφορία στο θάλαμο της δεξαμενής που δεν γίνεται άντληση. Η φορά της ελίκωσης της ροής στον αγωγό συμπίπτει στις περισσότερες περιπτώσεις με αυτήν του υδραυλικού μοντέλου. Η γωνία ελίκωσης θ, η οποία υπολογίστηκε με βάση το μέτρο της εφαπτομενικής ταχύτητας, ήταν μεγαλύτερη στο μεγάλο βάθος ύδατος και διαφορετική σε όλες τις περιπτώσεις από αυτήν που μετρήθηκε στο υδραυλικό μοντέλο. / -
98

Métamatériaux pour les ondes à la surface de l'eau / Metamaterials for water waves

Bobinski, Tomasz 27 June 2016 (has links)
Cette thèse porte sur l’étude numérique et expérimentale de l’utilisation de métamatériaux pour le contrôle des ondes à la surface de l’eau. Dans la première partie, nous avons montré comment focaliser les ondes à la surface de l’eau en utilisant une analogie existant avec des métamatériaux électromagnétiques de permittivité diélectrique quasi nulle qualifiés de ”epsilon-near-zero”. Cela a permis d’adapter le motif de phase à l’interface circulaire entre deux domaines présentant un contraste élevé de profondeur d’eau. L’analogie a donné lieu a un comportement fortement non linéaire des ondes, qui se manifeste par la génération d’une cascade de points focaux associés à des sous-multiples de longueurs d’onde par rapport à l’onde incidente. La deuxième application envisagée des métamatériaux pour les ondes à la surface est de rendre invisible les défauts géométriques d’un guide pour un observateur situé en champ lointain. Dans le premier projet lié au cloaking, des guides d’onde possédant différentes sections transverses ont été analysés. L’efficacité de la bathymétrie, donnée par la cartographie conformationnelle, a été evaluée numériquement en termes de propriétés de diffusion. Dans le second projet, nous avons montré numériquement comment rendre invisible un cylindre qui est décalé de l’axe d’un guide d’onde. Utiliser une bathymétrie de cloaking lisse autour du cylindre permet de reduire de manière significative la dispersion dans une large gamme de frequences. Des experiences réalisées avec des bathymétries conformes aux simulations ont confirmé une augmentation de la transmission par rapport à un scenario de référence avec fond plat. / This thesis presents numerical and experimental results concerning usage of metamaterials for water waves control. Two applications were considered. Firstly, we showed how to focus water waves using analogy to a group of metamaterials called epsilon-near-zero. This allowed to tailor phase pattern at the circular interface between two domains with high contrast in water depth. The analogy resulted in highly nonlinear behaviour of waves, manifested by sub-wavelength cascade of focal spots with respect to the incident wave. The second considered application of metamaterials for water waves was hiding (cloaking) defects in a waveguide from the far-field observer. In the first project, related to cloaking, waveguide with varying cross-sections was analyzed. The efficiency of bathymetry, rendered by conformal mapping, was evaluated in terms of scattering properties. The influence of water waves dispersivity on the cancellation of scattering was also determined. Cloaking properties of the obtained bathymetry were experimentally confirmed using a wave packet characterized by broadband spectrum. In the second project, we showed how to cloak a cylinder that is shifted from the centreline of a waveguide. Smooth cloaking bathymetry surrounding a cylinder was able to significantly reduce the scattering in broad range of frequencies. The experimental counterparts confirmed increase in transmission with respect to a reference case with flat bathymetry. The remainder of the thesis presents novel method for the analysis of fringe profilometry images. Performance of the new method was compared to the Fourier Transform Profilometry. We obtained significant enhancement in spectral capabilities.
99

Etude de l'interaction entre 14-3-3 epsilon et CD13/APN dans la communication os/cartilage au cours de l'arthrose / Study of interaction between 14-3-3 epsilon and CD13/APN in bone/cartilage communication during osteoarthritis

Nefla, Meriam 27 September 2016 (has links)
L’arthrose est la pathologie articulaire la plus fréquente, caractérisée par une destruction progressive du cartilage articulaire et impliquant une communication anormale entre l'os sous-chondral et le cartilage. Notre équipe a identifié la protéine 14-3-3ε comme un médiateur soluble secrété par l’os et capable d’altérer l'homéostasie du cartilage en stimulant l’expression de MMP-3 et MMP-13, deux métalloprotéases impliquées dans la dégradation du cartilage au cours de l’arthrose. CD13/APN, récepteur potentiel pour cette protéine, a été mis en évidence à la surface des chondrocytes murins et humains. Le but de cette étude était d’étudier son implication dans la réponse des chondrocytes à 14-3-3ε. L’invalidation de CD13/APN par des siRNA ou des anticorps bloquants, réduit significativement l’effet catabolique chondrocytaire induit par 14-3-3ε. Les chondrocytes articulaires possèdent une activité APN mais elle n’est pas modifiée en présence de 14-3-3ε. Nous avons mis en évidence la présence d’une interaction directe entre 14-3-3ε et CD13/APN grâce à la technologie SPR (Surface Plasmon Resonance) et le système Biacore. En utilisant 14-3-3ε marquée à la biotine, nous avons montré que 14-3-3ε est capable de se lier à la surface des chondrocytes via CD13/APN. Nous avons donc eu recours ensuite aux études de modélisation in silico qui ont permis d’identifier le résidu Y582 phosphorylé appartenant à la séquence E579FNYVW584 de CD13/APN, comme résidu indispensable pour sa liaison à 14-3-3ε. Ce travail de thèse permet de mieux comprendre le mécanisme d’action de 14-3-3ε et propose l’interaction entre 14-3-3ε et CD13 comme une nouvelle cible thérapeutique dans l’arthrose. / Osteoarthritis (OA) is a whole-joint disease characterized by progressive destruction of articular cartilage involving abnormal communication between subchondral bone and cartilage. Our team identified 14-3-3ε protein as a subchondral bone soluble mediator altering cartilage homeostasis. This protein acts as a potent stimulatory factor of MMP-3 and MMP-13 involved in the degradation of cartilage matrix in OA. CD13/APN, potential receptor of this protein, was identified on the surface of chondrocytes. The aim of this study was to investigate its involvement in chondrocytes response to 14-3-3ε. CD13/APN invalidation, using the siRNA strategy and blocking antibodies, reduces significantly the catabolic effect induced by 14-3-3ε in chondrocytes. APN activity was identified in chondrocytes but found unchanged following stimulation with 14-3-3ε. Then, we have revealed the presence of a direct interaction between 14-3-3ε and CD13/APN through the SPR (Surface Plasmon Resonance) and the Biacore system. Using biotin-labeled 14-3-3ε, we have shown that 14-3-3ε is able to bind to the surface of chondrocytes in a manner that is dependent on CD13/APN. It was then necessary to identify the putative motifs involved in this interaction. We therefore used in silico modelling studies which have identified the phosphorylated residue Y582, belonging to the E579FNYVW584 sequence of CD13/APN, as a critical residue for its binding to 14-3-3ε. This thesis work suggest that CD13 plays its receptor role to bind 14-3-3ε and transmit its signal in chondrocytes to induce a catabolic phenotype similar to that observed in OA. Thus, 14-3-3ε-CD13 interaction could be a novel therapeutic target in OA.
100

Moving-Average approximations of random epsilon-correlated processes

Kandler, Anne, Richter, Matthias, vom Scheidt, Jürgen, Starkloff, Hans-Jörg, Wunderlich, Ralf 31 August 2004 (has links)
The paper considers approximations of time-continuous epsilon-correlated random processes by interpolation of time-discrete Moving-Average processes. These approximations are helpful for Monte-Carlo simulations of the response of systems containing random parameters described by epsilon-correlated processes. The paper focuses on the approximation of stationary epsilon-correlated processes with a prescribed correlation function. Numerical results are presented.

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