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Barshalder 1 : A cemetery in Grötlingbo and Fide parishes, Gotland, Sweden, c. AD 1-1100. Excavations and finds 1826-1971Rundkvist, Martin January 2003 (has links)
The prehistoric cemetery of Barshalder is located along the main road on the boundary between Grötlingbo and Fide parishes, near the southern end of the island of Gotland in the Baltic Sea. The cemetery was used from c. AD 1-1100. The level of publication in Swedish archaeology of the first millennium AD is low compared to, for instance, the British and German examples. Gotland’s rich Iron Age cemeteries have long been intensively excavated, but few have received monographic treatment. This publication is intended to begin filling this gap and to raise the empirical level of the field. It also aims to make explicit and test the often somewhat intuitively conceived results of much previous research. The analyses deal mainly with the Migration (AD 375–540), Vendel (AD 520–790) and Late Viking (AD 1000–1150) Periods. The following lines of inquiry have been prioritised. 1. Landscape history, i.e. placing the cemetery in a landscape-historical context. (Vol. 1, section 2.2.6) 2. Migration Period typochronology, i.e. the study of change in the grave goods. (Vol. 2, chapter 2) 3. Social roles: gender, age and status. (Vol. 2, chapter 3) 4. Religious identity in the 11th century, i.e. the study of religious indicators in mortuary customs and grave goods, with particular emphasis on the relationship between Scandinavian paganism and Christianity.. (Vol. 2, chapter 4) Barshalder is found to have functioned as a central cemetery for the surrounding area, located on peripheral land far away from contemporary settlement, yet placed on a main road along the coast for maximum visibility and possibly near a harbour. Computer supported correspondence analysis and seriation are used to study the gender attributes among the grave goods and the chronology of the burials. New methodology is developed to distinguish gender-neutral attributes from transgressed gender attributes. Sub-gender grouping due to age and status is explored. An independent modern chronology system with rigorous type definitions is established for the Migration Period of Gotland. Recently published chronology systems for the Vendel and Viking Periods are critically reviewed, tested and modified to produce more solid models. Social stratification is studied through burial wealth with a quantitative method, and the results are tested through juxtaposition with several other data types. The Late Viking Period graves of the late 10th and 11th centuries are studied in relation to the contemporary Christian graves at the churchyards. They are found to be symbolically soft-spoken and unobtrusive, with all pagan attributes kept apart from the body in a space between the feet of the deceased and the end of the over-long inhumation trench. A small number of pagan reactionary graves with more forceful symbolism are however also identified. The distribution of different 11th century cemetery types across the island is used to interpret the period’s confessional geography, the scale of social organisation and the degree of allegiance to western and eastern Christianity. 11th century society on Gotland is found to have been characterised by religious tolerance, by an absence of central organisation and by slow piecemeal Christianisation.
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Barshalder 2 : Studies of late Iron Age GotlandRundkvist, Martin January 2003 (has links)
The prehistoric cemetery of Barshalder is located along the main road on the boundary between Grötlingbo and Fide parishes, near the southern end of the island of Gotland in the Baltic Sea. The ceme-tery was used from c. AD 1-1100. The level of publication in Swedish archaeology of the first millennium AD is low compared to, for instance, the British and German examples. Gotland’s rich Iron Age cemeteries have long been intensively excavated, but few have received monographic treatment. This publication is intended to begin filling this gap and to raise the empirical level of the field. It also aims to make explicit and test the often somewhat intuitively conceived re-sults of much previous research. The analyses deal mainly with the Migration (AD 375–540), Vendel (AD 520–790) and Late Viking (AD 1000–1150) Periods. The following lines of inquiry have been prioritised. 1. Landscape history, i.e. placing the cemetery in a landscape-historical context. (Vol. 1, section 2.2.6) 2. Migration Period typochronology, i.e. the study of change in the grave goods. (Vol. 2, chapter 2) 3. Social roles: gender, age and status. (Vol. 2, chapter 3) 4. Religious identity in the 11th century, i.e. the study of religious indicators in mortuary cus-toms and grave goods, with particular emphasis on the relationship between Scandinavian paganism and Christianity. (Vol. 2, chapter 4) Barshalder is found to have functioned as a central cemetery for the surrounding area, located on pe-ripheral land far away from contemporary settle-ment, yet placed on a main road along the coast for maximum visibility and possibly near a harbour. Computer supported correspondence analysis and seriation are used to study the gender attributes among the grave goods and the chronology of the burials. New methodology is developed to distin-guish gender-neutral attributes from transgressed gender attributes. Sub-gender grouping due to age and status is explored. An independent modern chronology system with rigorous type definitions is established for the Migration Period of Gotland. Recently published chronology systems for the Vendel and Viking Periods are critically reviewed, tested and modified to produce more solid models. Social stratification is studied through burial wealth with a quantitative method, and the results are tested through juxtaposition with several other data types. The Late Viking Period graves of the late 10th and 11th centuries are studied in relation to the contemporary Christian graves at the churchyards. They are found to be symbolically soft-spoken and unobtrusive, with all pagan attributes kept apart from the body in a space between the feet of the deceased and the end of the over-long inhumation trench. A small number of pagan reactionary graves with more forceful symbolism are however also identified. The distribution of different 11th cen-tury cemetery types across the island is used to in-terpret the period’s confessional geography, the scale of social organisation and the degree of alle-giance to western and eastern Christianity. 11th century society on Gotland is found to have been characterised by religious tolerance, by an absence of central organisation and by slow piecemeal Christianisation.
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Enumerative combinatorics related to partition shapesSjöstrand, Jonas January 2007 (has links)
This thesis deals with enumerative combinatorics applied to three different objects related to partition shapes, namely tableaux, restricted words, and Bruhat intervals. The main scientific contributions are the following. Paper I: Let the sign of a standard Young tableau be the sign of the permutation you get by reading it row by row from left to right, like a book. A conjecture by Richard Stanley says that the sum of the signs of all SYTs with n squares is 2^[n/2]. We prove a generalisation of this conjecture using the Robinson-Schensted correspondence and a new concept called chess tableaux. The proof is built on a remarkably simple relation between the sign of a permutation pi and the signs of its RS-corresponding tableaux P and Q, namely sgn(pi) = (−1)^v sgn(P)sgn(Q), where v is the number of disjoint vertical dominoes that fit in the partition shape of P and Q. The sign-imbalance of a partition shape is defined as the sum of the signs of all standard Young tableaux of that shape. As a further application of the sign-transferring formula above, we also prove a sharpening of another conjecture by Stanley concerning weighted sums of squares of sign-imbalances. Paper II: We generalise some of the results in paper I to skew tableaux. More precisely, we examine how the sign property is transferred by the skew Robinson-Schensted correspondence invented by Sagan and Stanley. The result is a surprisingly simple generalisation of the ordinary non-skew formula above. As an application, we find vanishing weighted sums of squares of sign-imbalances, thereby generalising a variant of Stanley’s second conjecture. Paper III: The following special case of a conjecture by Loehr and Warrington was proved by Ekhad, Vatter, and Zeilberger: There are 10^n zero-sum words of length 5n in the alphabet {+3,−2} such that no consecutive subword begins with +3, ends with −2, and sums to −2. We give a simple bijective proof of the conjecture in its original and more general setting where 3 and 2 are replaced by any relatively prime positive integers a and b, 10^n is replaced by ((a+b) choose a)^n, and 5n is replaced by (a+b)n. To do this we reformulate the problem in terms of cylindrical lattice walks which can be interpreted as the south-east border of certain partition shapes. Paper IV: We characterise the permutations pi such that the elements in the closed lower Bruhat interval [id,pi] of the symmetric group correspond to non-capturing rook configurations on a skew Ferrers board. These intervals turn out to be exactly those whose flag manifolds are defined by inclusions, as defined by Gasharov and Reiner. The characterisation connects Poincaré polynomials (rank-generating functions) of Bruhat intervals with q-rook polynomials, and we are able to compute the Poincaré polynomial of some particularly interesting intervals in the finite Weyl groups A_n and B_n. The expressions involve q-Stirling numbers of the second kind, and for the group A_n putting q = 1 yields the poly-Bernoulli numbers defined by Kaneko. / Ämnet för denna avhandling är enumerativ kombinatorik tillämpad på tre olika objekt med anknytning till partitionsformer, nämligen tablåer, begränsade ord och bruhatintervall. Dom viktigaste vetenskapliga bidragen är följande. Artikel I: Låt tecknet av en standardtablå vara tecknet hos permutationen man får om man läser tablån rad för rad från vänster till höger, som en bok. En förmodan av Richard Stanley säjer att teckensumman av alla standardtablåer med n rutor är 2^[n/2]. Vi visar en generalisering av denna förmodan med hjälp av Robinson-Schensted-korrespondensen och ett nytt begrepp som vi kallar schacktablåer. Beviset bygger på ett anmärkningsvärt enkelt samband mellan tecknet hos en permutation pi och tecknen hos dess RS-motsvarande tablåer P och Q, nämligen sgn(pi)=(-1)^v sgn(P)sgn(Q), där v är antalet disjunkta vertikala dominobrickor som får plats i partitionsformen hos P och Q. Teckenobalansen hos en partitionsform definieras som teckensumman av alla standardtablåer av den formen. Som en ytterligare tillämpning av formeln för teckenöverföring ovan bevisar vi också en starkare variant av en annan förmodan av Stanley som handlar om viktade summor av kvadrerade teckenobalanser. Artikel II: Vi generaliserar några av resultaten i artikel I till skeva tablåer. Närmare bestämt undersöker vi hur teckenegenskapen överförs av Sagan och Stanleys skeva Robinson-Schensted-korrespondens. Resultatet är en förvånansvärt enkel generalisering av den vanliga ickeskeva formeln ovan. Som en tillämpning visar vi att vissa viktade summor av kvadrerade teckenobalanser blir noll, vilket leder till en generalisering av en variant av Stanleys andra förmodan. Artikel III: Följande specialfall av en förmodan av Loehr och Warrington bevisades av Ekhad, Vatter och Zeilberger: Det finns 10^n ord med summan noll av längd 5n i alfabetet {+3,-2} sådana att inget sammanhängande delord börjar med +3, slutar med -2 och har summan -2. Vi ger ett enkelt bevis för denna förmodan i dess ursprungliga allmännare utförande där 3 och 2 byts ut mot vilka som helst relativt prima positiva heltal a och b, 10^n byts ut mot ((a+b) över a)^n och 5n mot (a+b)n. För att göra detta formulerar vi problemet i termer av cylindriska latticestigar som kan tolkas som den sydöstra gränslinjen för vissa partitionsformer. Artikel IV: Vi karakteriserar dom permutationer pi sådana att elementen i det slutna bruhatintervallet [id,pi] i symmetriska gruppen motsvarar ickeslående tornplaceringar på ett skevt ferrersbräde. Dessa intervall visar sej vara precis dom vars flaggmångfalder är definierade av inklusioner, ett begrepp introducerat av Gasharov och Reiner. Karakteriseringen skapar en länk mellan poincarépolynom (ranggenererande funktioner) för bruhatintervall och q-tornpolynom, och vi kan beräkna poincarépolynomet för några särskilt intressanta intervall i dom ändliga weylgrupperna A_n och B_n. Uttrycken innehåller q-stirlingtal av andra sorten, och sätter man q=1 för grupp A_n så får man Kanekos poly-bernoullital. / QC 20100818
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D. Joaquim de Sousa Saraiva : do declinio da diocese de Pequim a contribuicao para a historiografia Macaense = 索神父 / Do declinio da diocese de Pequim a contribuicao para a historiografia Macaense;"索神父"Sousa, Acacio Fernando de, January 1995 (has links)
University of Macau / Faculty of Social Sciences and Humanities / Department of Portuguese
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澳門特區政府中文行政公文優化研究 = The research on the Chinese administration official document optimization of Macau Special Administrative Region / research on the Chinese administration official document optimization of Macau Special Administrative Region吳惠芬 January 2008 (has links)
University of Macau / Faculty of Social Sciences and Humanities / Department of Chinese
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Increasing temporal, structural, and spectral resolution in images using exemplar-based priorsHolloway, Jason 16 September 2013 (has links)
In the past decade, camera manufacturers have offered smaller form factors, smaller pixel sizes (leading to higher resolution images), and faster processing chips to increase the performance of consumer cameras.
However, these conventional approaches have failed to capitalize on the spatio-temporal redundancy inherent in images, nor have they adequately provided a solution for finding $3$D point correspondences for cameras sampling different bands of the visible spectrum. In this thesis, we pose the following question---given the repetitious nature of image patches, and appropriate camera architectures, can statistical models be used to increase temporal, structural, or spectral resolution? While many techniques have been suggested to tackle individual aspects of this question, the proposed solutions either require prohibitively expensive hardware modifications and/or require overly simplistic assumptions about the geometry of the scene.
We propose a two-stage solution to facilitate image reconstruction; 1) design a linear camera system that optically encodes scene information and 2) recover full scene information using prior models learned from statistics of natural images. By leveraging the tendency of small regions to repeat throughout an image or video, we are able to learn prior models from patches pulled from exemplar images.
The quality of this approach will be demonstrated for two application domains, using low-speed video cameras for high-speed video acquisition and multi-spectral fusion using an array of cameras. We also investigate a conventional approach for finding 3D correspondence that enables a generalized assorted array of cameras to operate in multiple modalities, including multi-spectral, high dynamic range, and polarization imaging of dynamic scenes.
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Photojournalism in War and Armed Conflicts : Professional Photography and the Framing of Victimhood in World Press Photos of the YearBelow, Jelka Ninja January 2010 (has links)
During the last decades, the presence of visual media has increased dramatically. However, very little empirical research has been carried out to determine the implication of the medium photograph as a visual information transmitter. The aim of this study was therefore to investigate the characteristics of professional press photos that relate to war and armed conflicts and to examine the framing of victimhood. A thorough literature review as well as an iconographic interpretation of World Press Photos serves to ascertain data in order to permit answering the research questions. The World Press Photo Foundation is the subject of research as it represents the most prestigious international competition for press photography at present and thus acts as an agenda-setter. That highlights the implication of its decisions about professional photographs since its coverage of certain issues biases the international media coverage of the same. It also affects the development of professional photojournalism. In this context the meaning of photographs in today’s visual media societies can be discussed.
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Mesoscopic wave phenomena in electronic and optical ring structures / Mesoskopische Wellenphänomene in elektronischen und optischen RingstrukturenHentschel, Martina 14 November 2001 (has links) (PDF)
Gegenstand dieser Arbeit sind Wellenphänomene in mesoskopischen Ringstrukturen. In Teil I der Arbeit befassen wir uns mit spinabhängigem Transport von Elektronen in effektiv eindimensionalen Ringen in Gegenwart inhomogener Magnetfelder. Wir benutzen die exakten Lösungen der Schrödinger-Gleichung im allgemeinen nicht-adiabatischen Fall in einem Transfer-Matrix-Formalismus und untersuchen Auswirkungen von geometrischen Phasen auf den Magnetwiderstand. Für den Spezialfall eines Magnetfeldes in der Ringebene sagen wir einen interessanten Spin-Flip-Effekt vorher, der die Steuerung der Polarisationsrichtung von Elektronen über einen externen Aharonov-Bohm-Fluß erlaubt. Optische mesoskopische Systeme sind Thema von Teil II dieser Arbeit. Wir betrachten zweidimensionale annulare Strukturen, charakterisiert durch unterschiedliche Brechungsindizes, sowohl im klassischen Bild der geometrischen Optik als auch mit Wellenmethoden auf der Grundlage der Maxwellschen Gleichungen. Insbesondere diskutieren wir erstmals eine Streumatrixbeschreibung optischer Mikroresonatoren und wenden sie auf das dielektrische annulare Billard an. Ein Vergleich der Ergebnisse des Wellen- und Strahlenbildes liefert eine gute Übereinstimmung, jedoch sind im Grenzfall großer Wellenlängen von der Ordnung der Systemabmessungen Korrekturen zum Strahlenbild nötig. Wir zeigen am Beispiel von Fresnel-Gesetzen für gekrümmte Oberflächen erstmals, daß der Goos-Hänchen-Effekt diese Korrekturen quantitativ erfaßt. Ausgehend von der Wellenbeschreibung leiten wir neue analytische Formeln für verallgemeinerte Fresnel-Gesetze für beide möglichen Polarisationsrichtungen ab. Die Anwendung des Strahlenbildes erlaubt eine schlüssige Interpretation eines Experiments mit einer quadrupolaren Glasfaser, außerdem schlagen wir Strahlenkonzepte als Grundlage der Konstruktion von Mikrolasern mit maßgeschneiderten Charakteristika vor. / In this work we investigate wave phenomena in mesoscopic systems using different theoretical approaches. In Part I, we focus on effectively one-dimensional electronic ring structures and address the phenomenon of geometric phases in spin-dependent electronic transport in the presence of non-uniform magnetic fields. In the general non-adiabatic case, exact solutions of the Schrödinger equation are used in a transfer matrix formalism to compute the transmission probability through the ring. In the magneto-conductance we identify clear signatures of interference effects due to geometric phases, for example in rings where the non-uniform field is created by a central micromagnet. For the special case of an in-plane magnetic field we predict an interesting spin-flip effect that allows one to control the spin polarization of electrons by applying an external Aharonov-Bohm flux. Optical mesoscopic systems are the subject of Part II. We consider two-dimensional annular structures characterized by different refractive indices, and apply classical methods from geometric optics as well as wave concepts based on Maxwell's equations. For the first time, an S-matrix approach is successfully employed in the description of resonances in optical microresonators; in particular we propose the dielectric annular billiard as an attractive model system. Comparing ray and wave pictures, we find general agreement, except for large wavelengths of the order of the system size, where corrections to the ray model are necessary. The Goos-Hänchen effect as an extension of the ray picture is shown to quantitatively account for wave modifications of Fresnel's laws due to curved interfaces. We derive novel analytical expressions for the corrected Fresnel formulas for both polarizations of light. Motivated by the successful ray description, we give a conclusive interpretation of a recent filter experiment on a quadrupolar glass fibre, and suggest novel concepts for microresonator-based lasers.
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Crossroads of Enlightenment 1685-1850 : exploring education, science, and industry across the Delessert network2015 March 1900 (has links)
The Enlightenment did not end with the French Revolution but extended into the
nineteenth century, effecting a transformation to modernity. By 1850, science became increasingly institutionalized and technology hastened transmission of cultural exchange. Restricting Enlightenment to solitary movements, philosophic text, or national contexts ultimately creates insular interpretations. The Enlightenment was instead a transnational phenomenon, of interconnected communities, from diverse geographical and cultural spaces. A revealing example is the Delessert family. Their British-Franco-Swiss network demonstrates the uniqueness, extent, and duration of the Enlightenment.
This network’s origins lie in the 1680s. French and British desires for stability resulted in contrasting policies. Toleration, through partial rights, let British Dissenters become leading educators, manufacturers, and natural philosophers by 1760. Conversely, Huguenots were stripped of rights. Thousands fled persecution, and France’s rivals profited by welcoming waves of industrious Huguenots. French refugee communities became vital printing centres, specializing in Enlightenment attacks on the Ancien régime, and facilitated the expansion of the Delessert network. The Delessert banking family made a generational progression from Geneva to Lyon to Paris, linking them to Jean-Jacques Rousseau. His friendship fostered passions for botany and education. The Delesserts parlayed this into participation in Enlightenment science and industry, connecting them to the Lunar Society, Genevan radicals, and British reformers.
By 1780, a transition toward modernity began. Grand Tours shifted from places of erudition to practical sites of production. Lunar men sent sons to the Continent for practical education, as Franco-Swiss visited English manufactories and Scottish universities to expand knowledge.
Moderates greeted the French Revolution with enthusiasm. In the early 1790s this changed significantly. Royalist mobs threatened Lunar men, destroying property, in Birmingham. In France, moderates tried to defend the monarchy from republican mobs. Even so, the network, fragmented both by revolution and war, continued espousing reform and assisting members who were jailed, endangered, or escaping to America.
The Delessert network reconnected in 1801. Franco-Swiss toured Britain as Britons visited Paris, gathering at the hôtel Delessert, a crossroads of the Enlightenment. New societies encouraged science, industry, and philanthropy. Enlightenment exchange continued, despite warfare, into the nineteenth century. Industrial partnerships and scientific collaborations, formed during the peace, circumvented trade barriers. Over three generations (1760-1850) cosmopolitanism helped usher in a transition to modernity. Ultimately, the Delessert network’s endurance challenges traditional interpretations of the Enlightenment, and the Industrial Revolution.
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Μελέτες στη θεωρία χορδών και εφαρμογές της μη-Αβελιανής Τ-δυϊκότητας σε υπερβαρύτητα και στην αντιστοιχία AdS/CFT / Studies in string theory and applications of non-Abelian T-duality in supergravity and in AdS/CFT correspondenceΊτσιος, Γεώργιος 05 February 2015 (has links)
Στην παρούσα διδακτορική διατριβή μελετάμε εφαρμογές οι οποίες σχετίζονται με την μη-Αβελιανή Τ-δυϊκότητα και την αντιστοιχία AdS/CFT. Στο πρώτο μέρος, το οποίο αντιστοιχεί στο πρώτο κεφάλαιο της διατριβής, παρουσιάζουμε συνοπτικά τα απαραίτητα μαθηματικά εργαλεία που απαιτούνται για την καλύτερη κατανόηση των κεφαλαίων που ακολουθούν. Στο δεύτερο μέρος, το οποίο αποτελείται από τα κεφάλαια 2,3 και 4, ασχολούμαστε με την έννοια της μη-Αβελιανής Τ-δυϊκότητας. Ποιο συγκεκριμένα, στο δεύτερο κεφάλαιο παρουσιάζουμε τους κανόνες Buscher της Αβελιανής Τ-δυϊκότητα καθώς και την γενίκευση τους στην μη-Αβελιανή περίπτωση. Επίσης στο κεφάλαιο αυτό δείχνουμε τον τρόπο με τον οποίο μπορούμε να εφαρμόσουμε τους κανόνες της μη-Αβελιανής Τ-δυϊκότητας σε υπόβαθρα υπερβαρύτητας τύπου II τα οποία περιλαμβάνουν πεδία Ramond-Ramond. Η διαδικασία αυτή μπορεί να θεωρηθεί σαν μια τεχνική κατασκευής νέων λύσεων υπερβαρύτητας. Στο τρίτο κεφάλαιο θεωρούμε μια γενική κατηγορία υποβάθρων υπερβαρύτητας με ισομετρία SO(4) στα οποία εφαρμόζουμε τον μετασχηματισμό της μη-Αβελιανής Τ-δυϊκότητας ως προς την υποομάδα SU(2) της ομάδας ισομετρίας. Πραγματοποιώντας διαστατική ελάττωση στην αρχική και την δυϊκή θεωρία καταλήγουμε στην ίδια επταδιάστατη θεωρία. Ως αποτέλεσμα, οποιαδήποτε λύση αυτής της επταδιάστατης θεωρίας μπορεί να ανυψωθεί ταυτόχρονα στο αρχικό και στο δυϊκό υπόβαθρο. Η παρατήρηση αυτή μας παρέχει μια αντιστρεπτή απεικόνιση μεταξύ δυο λύσεων υπερβαρύτητας τύπου II οι οποίες συνδέονται με έναν μετασχηματισμό μη-Αβελιανής Τ-δυϊκότητας. Επίσης, για την συγκεκριμένη περίπτωση υποβάθρων αποδεικνύουμε ότι το δυϊκό υπόβαθρο διατηρεί τη μισή υπερσυμμετρία σε σχέση με το αρχικό. Στο τέταρτο κεφάλαιο μελετάμε τη δράση της μη-Αβελιανής Τ-δυϊκότητας σε μια σειρά από υπόβαθρα με υπερσυμμετρία N=1 των οποίων οι δυϊκές θεωρίες πεδίου είναι γνωστές. Σκοπός του κεφαλαίου αυτού είναι η μελέτη της μη-Αβελιανής Τ-δυϊκότητας στα πλαίσια της αντιστοιχίας AdS/CFT. Αυτό το επιτυγχάνουμε μελετώντας διάφορες ποσότητες των θεωριών πεδίου που αντιστοιχούν στο αρχικό και στο δυϊκό υπόβαθρο. Τέλος, στο πέμπτο κεφάλαιο κάνουμε χρήση τεχνικών ολογραφίας προκειμένου να μελετήσουμε το φαινόμενο της εισαγωγής φερμιονικών προσμίξεων σε τρισδιάστατες θεωρίες ύλης τύπου Chern-Simons, οι οποίες περιλαμβάνουν μεγάλο αριθμό γεύσεων. / In this thesis, we study applications which are related to the non-Abelian T-duality and the AdS/CFT correspondence. In the first part, which corresponds to the first chapter of the present thesis, we briefly present the basic mathematical tools required for the better understanding of the material included in the next chapters. In the second part, which consists of the chapters 2,3 and 4, we deal with the concept of non-Abelian T-duality. More concretely, in the second chapter we present the Buscher rules of the Abelian T-duality and we generalize them to the non-Abelian case. We also show how to implement the rules of non-Abelian T-duality in backgrounds of type II supergravity with non-vanishing Ramond-Ramond fields. This proccess can be seen as a generating technique of new supergravity backgrounds. In the third chapter we consider a general class of supergravity backgrounds with SO(4) isometry and we perform the non-Abelian T-duality transforation with respect to the SU(2) subgroup of SO(4). After a consistent truncation to seven dimensions of both the original and the dual background we reproduce the same seven dimensional theory. As a result, any solution of this seven dimensional theory can be uplifted simultaneously to both the original and the dual background. This provides an invertible map between two solutions of type II supergravity which are related with a non-Abelian T-duality transformation. Also, in the case of supergravity backgrounds considered here, we show that the dual background preserves the half supersymmetry with respect to the original one. In chapter 4, we study the action of non-Abelian T-duality on a series of N=1 supersymmetric backgrounds whose field theory duals are well understood. The aim of this chapter is to study the transformation of non-Abelian T-duality within the framework of the AdS/CFT correspondence. This is done by considering several observables of the field theories that correspond to both the original and the dual backgrounds. Finally, in chapter 5 we use holographic techniques in order to study the effect of the addition of fermionic impurities to the three dimensional Chern-Simons matter theories with a large number of flavors.
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