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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

Light Cone Qcd Sum Rules And Meson Physics

Kanik, Inanc 01 September 2008 (has links) (PDF)
In this thesis, we applied Light Cone QCD sum rules (LCSR) to several problems in meson physics. Semileptonic B-&gt / eta l v decays are important to get information on Cabibbo-Kobayashi-Maskawa (CKM) matrix elements. We calculated form factors of this decay in LCSR frame. Our results are confirmed by later studies and these similar studies had been used for enhancing result on b to u quark transition matrix element of CKM matrix by BaBar collaboration. We used LCSR method also for calculating coupling constant of radiative rho -&gt / eta photon decay since the analysis of the vector particle to pseudoscalar particle radiative decay with eta and eta&#039 / mesons in final state can provide insights to the long standing issue of the eta and eta&#039 / mixing. Our result g_{rho eta photon}=(1.4 &plusmn / 0.2) is very close to experimental value g_{ rho eta photon} = (1.42 &plusmn / 0.12). We also calculated magnetic moment of the rho meson in LCSR frame which is an important parameter since it is strongly related to internal structure of hadron. Our result 2.3 &plusmn / 0.5 in units of (e/2m_rho), is in better agreement with lattice QCD results than traditional QCD sum rules. Quark contents of light scalar mesons are still under debate and we analyzed phi -&gt / K K decays which is important for understanding the quark content of the f0 meson. Our final result is g_{phi KK} = 4.9 &plusmn / 0.8 which is in well agreement with existing experimental result g_{phi KK} = 4.8.
222

Entanglement In The Relativistic Quantum Mechanics

Yakaboylu, Enderalp 01 February 2010 (has links) (PDF)
In this thesis, entanglement under fully relativistic settings are discussed. The thesis starts with a brief review of the relativistic quantum mechanics. In order to describe the effects of Lorentz transformations on the entangled states, quantum mechanics and special relativity are merged by construction of the unitary irreducible representations of Poincar&eacute / group on the infinite dimensional Hilbert space of state vectors. In this framework, the issue of finding the unitary irreducible representations of Poincar&eacute / group is reduced to that of the little group. Wigner rotation for the massive particles plays a crucial role due to its effect on the spin polarization directions. Furthermore, the physical requirements for constructing the correct relativistic spin operator is also studied. Then, the entanglement and Bell type inequalities are reviewed. The special attention has been devoted to two historical papers, by EPR in 1935 and by J.S. Bell in 1964. The main part of the thesis is based on the Lorentz transformation of the Bell states and the Bell inequalities on these transformed states. It is shown that entanglement is a Lorentz invariant quantity. That is, no inertial observer can see the entangled state as a separable one. However, it was shown that the Bell inequality may be satisfied for the Wigner angle dependent transformed entangled states. Since the Wigner rotation changes the spin polarization direction with the increased velocity, initial dichotomous operators can satisfy the Bell inequality for those states. By choosing the dichotomous operators taking into consideration the Wigner angle, it is always possible to show that Bell type inequalities can be violated for the transformed entangled states.
223

Spinodal Instabilities In Symmetric Nuclear Matter Within A Nonlinear Relativistic Mean-field Approach

Acar, Fatma 01 August 2011 (has links) (PDF)
Spinodal instability mechanism and early development of density fluctuations for symmetric nuclear matter at finite temperature are studied. A stochastic extension of Walecka-type relativistic mean-field model including non-linear self-interactions of scalar mesons with NL3 parameter set is employed in the semi-classical approximation. The growth rates of unstable collective modes are investigated below the normal density and at low temperatures. The system exhibits most unstable behavior in longer wave lengths at baryon densities &rho / B = 0.4 &rho / 0 , while most unstable behavior occurs in shorter wavelengths at lower baryon densities &rho / B = 0.2 &rho / 0 . The unstable response of the system shifts towards longer wavelengths with the increasing temperature at both densities. The early growth of the density correlation functions are calculated, which provide valuable information about the initial size of the condensation and the average speed of condensing fragments. Furthermore, the relativistic results are compared with Skyrme type non-relativistic calculations. Qualitatively similar results are found in both non-relativistic and relativistic descriptions.
224

Discovery Potential Of Quantum Black Holes In Add Model With The Cms Detector

Gamsizkan, Halil 01 September 2011 (has links) (PDF)
With the long awaited start-up of the LHC, TeV scale physics is now in reach of the particles physicists to explore. There are many questions about the nature to be answered, and many more theories to be tested trying to answer them. The ADD model of extra dimensions is one such model, written to address the large mass hi- erarchy between the two fundamental energy scales in nature, the electroweak and the Planck scales. ADD model predicts stronger gravity at sub-millimeter distance scales, which would then lead to an interesting physical object to be produced at proton collusions at the LHC: Tiny quantum black holes. In this thesis we study the discovery potential of CMS for quantum black hole events for proton-proton collusions at sqrt(s) = 14 TeV. Our study details the trigger response of CMS, various criteria and methods for background rejection, affect of experimental uncertainties on measurements, for different model parameter values.
225

Microstructural And Mechanical Characterization Of Duplex Stainless Steel Grade 2205 Joined By Hybrid Plasma And Gas Metal Arc Welding

Tolunguc, Burcu 01 January 2012 (has links) (PDF)
In the present study, the applicability of the hybrid plasma arc welding, in which a keyhole is responsible of deep penetration and a filler wire electrode supplies a high deposition rate, was examined. The microstructural evolutions in grade 2205 duplex stainless steel plates joined by keyhole and melt-in techniques were investigated. The specimens obtained from welded plates having thickness of 8 mm were examined via optical and scanning electron microscopy. Metallographic investigations were supported by X-ray diffraction and energy dispersed spectra analyses by characterizing the phases formed after welding. Impact toughness properties, hardness profiles, and crack propagation behavior of welding zones were quantitatively and qualitatively compared for mechanical characterization. Fracture characteristics were determined via scanning electron microscopy examinations. It was observed that single-pass HPA weldment seemed to be free of secondary austenite precipitation in acicular form, which is inevitable in multi-pass conventional arc welding methods. Besides &delta / -ferrite was successfully kept under 70%, which is presented as a limit to not to deteriorate the mechanical properties of DSS. High linear welding speed and high power density supplied by HPAW presented narrower weld metal and heat affected zone with not only lower hardness but also higher impact toughness energies. Synergic effect of the keyhole formed by a plasma arc and the metal transfer supplied by gas metal arc gave reasonable dilution in the weld metal. Furthermore, fatigue crack growth tests revealed that crack propagation rates in HPAW joints were comparable to GMAW joints.
226

Wertanalyse strategischer Entscheidungen bei der Stahlherstellung untersucht am Beispiel der Erzeugung von Bändern aus nichtrostenden Stählen

Jüngling, Lorenz 11 March 2010 (has links) (PDF)
In der Stahlindustrie sind strategische Entscheidungen mit hohen Investitionsbedarfen verbunden und aufgrund komplexer Produktionsvorgänge oft nur schwer zu bewerten. Im Rahmen der Arbeit wird ein Modell vorgestellt, das eine Verbindung zwischen der Veränderung technischer Parameter im Produktionsnetzwerk und ihren Auswirkungen auf den Wert der Unternehmung zulässt. Hierfür werden die zukünftigen Freien Cashflows bestimmt, die aus der Betriebstätigkeit (Produktion und Vertrieb) der Unternehmung resultieren und diskontiert zu einem Unternehmenswert aufsummiert (DCF). Entscheidend hierbei ist der Trade-off zwischen der technischen Detailtreue des Modells und der Handhabbarkeit (Modularität) bei der kurzfristigen Bewertung strategischer Fragestellungen. Abschließend wird der Einsatz des Modells anhand von Beispielen demonstriert.
227

Entwurf und Realisierung einer Configuration Management Database nach ITIL für den Service Desk der SLUB Dresden

Niebling, Frank 20 December 2010 (has links) (PDF)
In der Arbeit wird der Entwurf und die Realisierung einer Configuration Management Database für den Service Desk der SLUB Dresden betrachtet. Es wird auf Grundlage von ITIL und den Anforderungen der SLUB ein Konzept zum Aufbau und zur Strukturierung der dabei relevanten Daten vorgestellt. Für den Import der Daten wird ein automatisiertes System geschaffen, das Daten aus verschiedenen Quellen mit der Configuration Management Database in regelmäßigen Abständen abgleicht. Der Service Desk erhält dadurch einen zentralen Zugriff auf Daten zu physikalischen Geräten sowie virtuellen Maschinen und kann diese in die Arbeitsprozesse integrieren. Zusätzlich wird das System durch den scriptbasierten Import von Verlinkungen zwischen virtuellen und physikalischen Servern und Ergebnissen aus der Geräte- und Netzwerküberwachung ergänzt. Schließlich wird betrachtet, welche weiteren Entwicklungsschritte auf Grundlage der vorgenommenen Änderungen möglich worden und welche Aspekte bei der Umsetzung dieser Schritte eine Rolle spielen.
228

Μελέτη της έκφρασης ορμονικών υποδοχέων στον πρωτοπαθή όγκο και στο λεμφαδένα φρουρό στο μελάνωμα και επιπτώσεις της στην έκβαση της νόσου

Σπυρόπουλος, Χαράλαμπος 19 August 2014 (has links)
Οι φυλετικές ορμόνες επηρεάζουν τη βιολογική συμπεριφορά του μελανώματος. Μετά την ανακάλυψη των οιστρογονικών υποδοχέων (ER) και ιδίως του υποδοχέα βήτα, η άποψη πως τα μελανώματα εκφράζουν χαμηλές συγκεντρώσεις ER αναθεωρήθηκε. Ο σκοπός της παρούσας μελέτης ήταν να διερευνήσει το βαθμό έκφρασης των ER στο πρωτοπαθές μελάνωμα αλλά και στο λεμφαδένα φρουρό αυτού που παριστά ένα σημαντικό σταθμό στη μεταστατική διαδικασία και να εκτιμήσει πιθανή συσχέτιση με την πρόγνωση και τη συνολική επιβίωση. Πραγματοποιήθηκε ανάλυση δεδομένων 60 ασθενών, μέσης ηλικίας 54,4 ± 14,5 ετών, με διάγνωση μελανώματος κατά την περίοδο 2001-2012. Όλοι οι ασθενείς υποβλήθηκαν σε βιοψία λεμφαδένα φρουρού, μετά την αναγνώρισή του με ραδιοϊσοτοπική λεμφαγγειογραφία. Εάν η ιστοπαθολογική εξέταση αναδείκνυε διήθηση του λεμφαδένα από το νεόπλασμα, διενεργείτο συμπληρωματικός λεμφαδενικός καθαρισμός, σε δεύτερο χρόνο. Με ανοσοϊστοχημική μέθοδο εκτιμήθηκε η έκφραση των οιστρογονικών υποδοχέων (ERα και ERβ) σε όλες τις δυνατές περιπτώσεις. Η έκφραση του ERα ήταν εξαιρετικά ασθενής, αναδεικνύοντας τον ERβ σαν τον επικρατούντα οιστρογονικό υποδοχέα, τόσο στον πρωτοπαθή όγκο, όσο και στο λεμφαδένα φρουρό. H εντονότερη ανοσοέκφραση του ERβ καταδείχθηκε σε λεπτά, λιγότερο διηθητικά μελανώματα με αρνητικούς λεμφαδένες φρουρούς. Επιπρόσθετα, η έκφραση του ERβ στον πρωτοπαθή όγκο σχετιζόταν σαφώς με το κυτταρικό μικροπεριβάλλον του, πιθανά επηρεάζοντας τη λεμφογενή διασπορά. Τα επίπεδα έκφρασης του ERβ είναι ελαττωμένα σταθερά σε επιθετικά μελανώματα, μεγάλου πάχους με μεταστατική νόσο στο λεμφαδένα φρουρό. Η αξιολόγησή τους υποδεικνύει έναν πιθανό δείκτη του μεταστατικού δυναμικού των μελανωμάτων και κατ’ επέκταση της πρόγνωσης της νόσου. / Steroid hormones seem to affect the biological behavior of melanoma. Prior to the discovery of estrogen receptor beta (ERb), melanomas were considered to contain low estrogen receptor concentrations. Furthermore, no studies have examined the role of estrogen receptor expression in sentinel lymph nodes (SLNs) of melanomas. The purpose of this study was to investigate the immunoexpression of estrogen receptors in malignant melanomas and SLNs and to examine any possible association with prognosis and overall survival. A retrospective analysis of prospectively collected data was conducted during a 12-year period (2001-2012). Sixty patients with mean age of 54.4 ± 14.5 years old diagnosed with melanomas after excision biopsy of pre-existing melanocytic lesions, were included in the study. All patients underwent wide excision of the primary tumor and SLN identification. Therapeutic lymph node dissection was conducted in cases where the final pathological report was indicative of SLN tumor invasion. Determination of estrogen receptor alpha (ERa) and beta (ERb) status by immunohistochemistry on tumor and nodal paraffin blocks was performed in all feasible cases. ERb but not ERa was the predominant estrogen receptor found in all primary tumors and SLNs examined. The most intense ERb immunostaining was seen in negative SLNs associated with thinner, less invading melanomas. ERb expression in the primary tumor seems to correlate with the cellular microenvironment, possibly altering the process of SLN invasion. ERb expression is down-regulated in aggressive melanomas with sentinel nodal disease, suggesting its possible usefulness as a surrogate marker for metastatic potential and prognosis in malignant melanoma.
229

Lee Miller - Künstlerporträts. Porträtfotografien von Pablo Picasso, Max Ernst und der künstlerischen Avantgarde von 1929 bis 1973. / Lee Miller - Portraits of Artists. Portrait photographs of Pablo Picasso, Max Ernst and the artistic avant-garde from 1929 to 1973.

Rohmann, Ivonne 24 January 2006 (has links)
No description available.
230

I do it, you do it, we do it. Just do it.

Bergelt, Sven 13 May 2014 (has links) (PDF)
Ermöglicht durch die Medientechnologien des Web 2.0 hat sich seit Mitte der 2000er Jahre ein kulturelles Nachahmungsphänomen im Internet entwickelt. YouTube, Flickr, Twitter und Co. haben zu einer Potenzierung und Beschleunigung der ohnehin vorhandenen ,Kultur des Kopierens’ geführt. Anhand der mehrteiligen Arbeit I’m too sad to tell you des Konzeptkünstlers Bas Jan Ader und deren Nachahmungen und Adaptionen wird hier beispielhaft untersucht, welche Auswirkungen, Potentiale und Begrenzungen sich aus dem Nachahmungsphänomen ableiten lassen und inwiefern der über die Videoplattformen erstellte User-Generated-Content als Archiv- und Quellenmaterial für eine künstlerische Forschung fungieren kann.

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