• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 192
  • 48
  • 35
  • 23
  • 14
  • 10
  • 6
  • 4
  • 4
  • 3
  • 3
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 386
  • 158
  • 97
  • 73
  • 73
  • 64
  • 45
  • 42
  • 33
  • 32
  • 31
  • 30
  • 30
  • 30
  • 27
  • 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.
81

ADS/CFT correspondence in a non-supersymmetric Yi-deformed background

Prinsloo, Andrea Helen 22 December 2008 (has links)
A non-supersymmetric Yi-deformed AdS/CFT correspondence has recently been conjectured by Frolov. A detailed description of both sides of this proposed gauge/string duality is presented. The analogy that exists between single trace gauge theory operators in the SU(3) sector and i-deformed SU(3) integrable spin chains is also discussed. Frolov, Roiban and Tseytlin’s leading order comparison between the ideformed spin chain coherent state action and i-deformed string worldsheet action in the semiclassical limit is reviewed. A particular Lax pair representation for the first order semiclassical i-deformed spin chain/string action is then constructed.
82

Viscosity Bound Violation in the MTZ Black Hole:

Martin, Luke January 2021 (has links)
Thesis advisor: Kevin Bedell / Using the AdS/CFT correspondence, it has been shown that the ratio of shear viscosity to entropy density is bounded from below in strongly coupled field theories with a gravity dual. More recently, this bound has been shown to be grossly violated in novel non-Fermi liquids and the unitary Fermi gas in the presence of superfluid fluctuations above T_c. Nevertheless, a holographic approach to such systems which break the lower bound have been strongly reliant on AdS spacetimes with massive gravitons. In this work, we propose a violation of the viscosity over entropy bound in 3+1 dimensional AdS spacetimes that support stable black hole solutions with non-zero scalar field. Such a black hole is shown to be characterized by a novel phase transition at large negative mass, where the underlying thermodynamics agrees with the Larkin-Ovchinnikov-Fulde-Ferrell (LOFF)-like phase seen in the unitary Fermi gas near Tc and the bound is similarly broken. Such a work paves the way for a holographic description of strongly-entangled quantum fluids at high Reynolds number. / Thesis (BS) — Boston College, 2021. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Scholar of the College. / Discipline: Physics.
83

Quantum information and the emergence of spacetime in the AdS/CFT correspondence / Quanteninformation und die Entstehung der Raumzeit in der SdS/CFT- Korrespondenz

Gerbershagen, Marius January 2022 (has links) (PDF)
This thesis studies connections between quantum information measures and geometric features of spacetimes within the AdS/CFT correspondence. These studies are motivated by the idea that spacetime can be thought of as an effect emerging from an underlying entanglement structure in the AdS/CFT correspondence. In particular, I study generalized entanglement measures in two-dimensional conformal field theories and their holographic duals. Unlike the ordinary entanglement entropy of a spatial subregion typically used in the AdS/CFT context, the generalization considered here measures correlations between different fields as well as between spatial degrees of freedom. I present a new gauge invariant definition of the generalized entanglement entropy applicable to both mixed and pure states as well as explicit results for thermal states of the S_N-orbifold theory of the D1/D5 system. Along the way, I develop computation techniques for conformal blocks on the torus and apply them to the calculation of the ordinary entanglement entropy for large central charge CFTs at finite size and finite temperature. The generalized Ryu-Takayanagi formula arising from these studies provides further support for the idea that entanglement and geometry are intrinsically linked in AdS/CFT. The results show that the holographic dual to the generalized entanglement entropy given by the length of a geodesic winding around black hole horizons or naked singularities probes subregions of spacetime that are inaccessible to Ryu-Takayanagi surfaces, thereby solving the puzzle of how these features of the spacetime are encoded in the boundary theory. Furthermore, I investigate quantum circuits embedded in two-dimensional conformal field theories as well as computational complexity measures therein. These investigations are motivated by conjectures relating computational complexity in conformal field theories to geometric features of black hole geometries. In this thesis, I study quantum circuits built up from conformal transformations. I investigate examples of computational complexity measures in these circuits related to geometric actions on coadjoint orbits of the Virasoro group and to the Fubini-Study metric. I then work out relations between these computational complexity measures and the dual gravitational theory. Moreover, I construct a bulk dual to the circuits in consideration and use this construction to study geometric realizations of computational complexity measures from first principles. The results of this part on the one hand rule out some possibilities for dual realizations of computational complexity in two-dimensional CFTs put forward in previous work while on the other hand providing a new robust dual realization of a computational complexity measure based on the Fubini-Study distance. / Diese Dissertation befasst sich mit Zusammenhängen zwischen Quanteninformationsmaßen und geometrischen Eigenschaften von Raumzeiten im Rahmen der AdS/CFT-Korrespondenz. Diese Untersuchungen sind motiviert durch die Idee, dass die Raumzeit in der AdS/CFT-Korrespondenz als ein Effekt verstanden werden kann, der aus einer zugrundeliegenden Verschränkungsstruktur entsteht. Insbesondere untersuche ich in dieser Arbeit verallgemeinerte Verschränkungsmaße in zweidimensionalen konformen Feldtheorien und deren holographisch duale Realisierungen. Anders als die normale Verschränkungsentropie einer räumlichen Teilregion, die üblicherweise im AdS/CFT-Kontext betrachtet wird, misst die verallgemeinerte Verschränkungsentropie Korrelationen sowohl zwischen verschiedenen Feldern als auch zwischen räumlichen Freiheitsgraden. Ich stelle eine neue eichinvariante Definition der verallgemeinerten Verschränkungsentropie, die sowohl für reine als auch für gemischte Zustände anwendbar ist, sowie explizite Berechnungen dieser Verschränkungsentropie in der S_N-Orbifaltigkeitstheorie des D1/D5-Systems vor. Nebenbei entwickle ich Berechnungsmethoden für konforme Blöcke auf dem Torus und wende diese auf die Berechnung der normalen Verschränkungsentropie für konforme Feldtheorien mit großer zentraler Ladung bei endlicher Systemgröße und endlicher Temperatur an. Die verallgemeinerte Ryu-Takayanagi-Formel, die sich aus diesen Betrachtungen ergibt, unterstützt die Idee, dass Verschränkung und Geometrie in der AdS/CFT-Korrespondenz untrennbar miteinander verbunden sind. Die Ergebnisse zeigen, dass das holographische Dual zur verallgemeinerten Verschränkungsentropie, gegeben durch die Länge einer Geodäte die sich um einen Ereignishorizont eines Schwarzen Lochs oder eine nackte Singularität windet, in Teilregionen der Raumzeit eindringt die für Ryu-Takayanagi-Flächen unerreichbar sind. Damit klären sie auf wie diese Eigenschaften der Raumzeit in der Randtheorie kodiert sind. Des weiteren untersuche ich Quantenschaltkreise eingebettet in zweidimensionale konforme Feldtheorie und deren Komplexität. Diese Untersuchungen sind motiviert durch Hypothesen, die Komplexitätstheorie mit Eigenschaften von Raumzeiten schwarzer Löcher in Verbindung bringen. In dieser Dissertation analysiere ich Quantenschaltkreise, die aus konformen Transformationen aufgebaut sind. Ich betrachte Komplexitätsmaße in diesen Schaltkreisen zusammenhängend mit geometrischen Wirkungen auf koadjungierten Orbits der Virasoro-Gruppe oder mit der Fubini-Study-Metrik und arbeite Zusammenhänge zwischen diesen Komplexitätsmaßen und Aspekten der dualen Gravitationstheorie heraus. Außerdem konstruiere ich das Dual der betrachteten Schaltkreise in der Gravitationstheorie und untersuche damit geometrische Realisierungen von Komplexitätsmaßen. Die Ergebnisse dieses Teils schließen einerseits einige Möglichkeiten für duale Realisierungen von Komplexitätsmaßen aus, die in vorigen Arbeiten vorgeschlagen wurden, ergeben aber andererseits eine robuste neue duale Realisierung eines Komplexitätsmaßes basierend auf der Fubini-Study-Metrik.
84

Spacetime Geometry from Quantum Circuits and Berry Phases in AdS/CFT / Geometrie der Raumzeit aus Quantenschaltkreisen und Berry-Phasen in AdS/CFT

Weigel, Anna-Lena January 2023 (has links) (PDF)
In this thesis, I establish new relations between quantum information measures in a two-dimensional CFT and geometric objects in a three-dimensional AdS space employing the AdS/CFT correspondence. I focus on two quantum information measures: the computational cost of quantum circuits in a CFT and Berry phases in two entangled CFTs. In particular, I show that these quantities are associated with geometric objects in the dual AdS space. / In dieser Arbeit stelle ich neue Beziehungen zwischen Quanteninformationsmaßen in einer zweidimensionalen CFT und geometrischen Objekten in einem dreidimensionalen AdS-Raum unter Verwendung der AdS/CFT-Korrespondenz her. Ich betrachte zwei Quanteninformationsmaße: die Rechenkosten eines Quantenschaltkreises in der CFT und Berry-Phasen in zwei verschränkten CFTs. Insbesondere zeige ich, dass diese Größen mit geometrischen Objekten im AdS-Raum assoziiert sind.
85

Processing world scale air traffic data to find Near Mid-Air Collisions

Hermansson, Leopold January 2023 (has links)
In order to increase the safety of all air travel, technologies that continueto augment the pilot's ability to avoid collisions and stay clear of danger areneeded. But, before these can be certified and deployed, their performance andpotential failure cases have to be understood. This requires evaluating a modelof the system on simulated encounters, consisting of different trajectoriesthat should replicate the real world. This is commonly done using a statistical encounter model, which produces largeamounts of data but relies on the accuracy of the statistical model, thuslimited in its ability to produce realistic data. The goal with this project isto create an encounter dataset of real trajectories that would provide analternative to encounter models. This is done using an ADS-B dataset from The OpenSky Network (provided byDaedalean AI), consisting of 226 billion air traffic data points from 2019.First, a solution to efficiently query and reconstruct trajectories from thedataset is designed and implemented. Using it, a NMAC (Near Mid-Air Collision)dataset is created to demonstrate the viability of ADS-B as a source forcreating an encounter dataset, and to prove the capabilities of the designedsolution.
86

Acceptable Ads guidelines, its effect on user experience and ad-noticeability

Weidenmark, Joel January 2020 (has links)
The Acceptable Ads Standard is a set of guidelines developed by the biggest ad-blocker company AdBlock Plus as an attempt to alleviate the largest need for ad-blocking programs; ads being annoying, irrelevant, and too intrusive. The guidelines inflict rules regarding how ads can be presented in order to be acceptable, thereby not disturbing the consumer. If a website follows these guidelines, their ads will not get blocked. The terms ad-avoidance and ad-irritation has been established by Cho et al. and Baek et al. [4]. The term ad-noticeability was added to these in order to express the behavior of seeing an ad, but not necessarily understanding what it’s trying to mediate. This study aims to examine the Acceptable Ads guidelines’ effect on user experience and ad-noticeability through a quantitative and qualitative study. The two studies were conducted with the help of two specially made test suites in the form of two websites, one with acceptable and one with non-acceptable ads. All participants went through the same set of tasks on the websites. In the quantitative study, data regarding what ads the participants’ had seen and what their experiences’ had been like was collected. Through the qualitative study, it was possible to get more elaborate answers to why certain ads were seen or missed and to get more in-depth answers regarding the participants’ experiences. Through the study, it was found that there is a difference in ad-noticeability and the user experience of ads between websites that contain either acceptable or non-acceptable ads. The results suggest that the Acceptable Ads guidelines affect user experience positively, i.e. leading to less ad-irritation or annoyance, but also affect ad-noticeability negatively. It was also found that cognitive ad-avoidance was greatly affected by task-oriented focus, both in cases with and without ads following acceptable / The Acceptable Ads Standard är en samling med riktlinjer utvecklade av det största företaget inom ad-blockers, AdBlock Plus. Dessa riktlinjer utvecklades som ett försök att motverka de största anledningarna till att konsumenter installerar ad-blockers: att reklam är irriterande, irrelevant, eller för påträngande. Dessa riktlinjer skapar regler för hur onlinereklam ska presenteras för att vara acceptabelt, och därmed inte störa konsumenterna. Om en hemsida följer dessa regler är tanken att deras reklam inte ska bli blockerad av installerade ad-blockers. Termerna ad-avoidance (“reklamundvikelse”) och ad-irritation (“reklamirritation”) har blivit etablerade av Cho et al. och Baek et al [4]. Termen ad-noticeability (att notera reklam) har blivit tillagt till dessa för att uttrycka beteendet att se reklam, utan att nödvändigtvis förstå den. Denna studie riktar sig till att undersöka Acceptable Ads påverkan på användarupplevelse och hur mycket reklam som noteras genom en kvantitativ och en kvalitativ studie. Dessa två studier genomfördes med hjälp av två specialtillverkade testsviter i formen av två hemsidor: en hemsida med acceptabel reklam och en med oacceptabel reklam. Alla testdeltagare gick igenom samma uppgifter på dessa hemsidor. I den kvalitativa studien fanns ett fokus på att samla in data gällande vad testdeltagare sett och upplevt. Genom den kvalitativa studien var det möjligt att få mer djupgående svar på varför viss reklam hade missats och hur deltagarna hade upplevt reklamen. Genom studien hittade man att det var skillnad på hur mycket reklam som noteras och på hur testdeltagare upplever reklam på hemsidor med acceptabel kontra oacceptabel reklam. Resultaten föreslår att riktlinjerna från Acceptable Ads påverkar användarupplevelsen positivt genom att minska irritation men också att de har en negativ påverkan på hur mycket reklam som noteras. Det visade sig också att kognitiv reklamundvikelse var mycket påverkat av ett uppgiftsorienterat fokus, både i fall med och utan acceptabel reklam.
87

Simultaneous Media Use and Advertising: The Effects of Salient Web Ads in a New Media World

Lou, Shanshan January 2013 (has links)
No description available.
88

Ska vi sponsra en podcast?

Ergeer, Emilia January 2017 (has links)
År 2007 undersökte Haygood reklam i amerikanska podcasts för att ta reda på dess mönster, och år 2010 valde McGowan att göra en liknande studie för att ta reda på om Haygoods teorier fortfarande stämde. Det visade sig att Haygoods teorier fortfarande var aktuella och på så vis hade teorierna hållit över en längre tid. Därmed är denna studiens syfte att undersöka om de amerikanska reklammönsterna går att applicera på reklam i svenska podcasts, trots att Sverige har fler lagar än USA kring hur reklam får framföras. Vidare kommer studien att undersöka lyssnarens attityd till reklam i podcasts, detta för att ta reda på vad lyssnaren anser om podcastreklams utformning och placering. Studien är genomförd med både en kvantitativ- och en kvalitativ metod. För att undersöka reklammönstret i svenska podcasts tillämpades en kvantitativ metod där podcasts på iTunes topp tio studerades under sex veckor. Samtliga podcasts analyserades och dokumenterades och jämfördes därefter med resultatet från McGowans studie (2010), då denna studien är den senare. Resultatet visade att the bookend effect (sv. bokstödseffekten) också finns i svenska podcasts, den förekommer däremot mer i amerikanska podcasts. Hur reklamen framförs påminner också om den amerikanska, exempelvis ”Vi är denna veckan sponsrade av…” kan liknas med ”Support for this podcast comes from...”. Andra reklammönster som går att applicera på svensk podcastreklam är självförsörjandereklam och återkommande sponsorer. För att undersöka lyssnarens attityd till podcastreklam tillämpades en kvalitativ metod i form av individuella intervjuer. Respondenterna fick lyssna på reklamutdrag från de undersökta podcasts och därefter svara på frågor kring reklamen. Det framkom att reklam är störande oavsett dess utformning och placering. Sponsrat prat, det vill säga när programledaren själv pratar, föredras framför traditionella reklamavbrott. Respondenterna föredrog att reklamen kom i början på avsnittet men att reklam i mitten var ok om det var sponsrat prat. Detta berodde på att de inte kände sig lika avbrutna med sponsrat prat som med exempelvis traditionellt reklamavbrott. / In 2007, Haygood examined US podcast ads to find out its pattern, and in 2010 McGowan chose to do a similar study to find out if Haygood's theories were still correct. It turned out thatHaygood's theories were still up to date and thus the theories had lasted for a long time. Therefore, this study's purpose is to investigate whether the U.S. advertising patterns can beapplied to advertisements in Swedish podcasts, even though Sweden have more laws than the US on how to advertise. In addition, the study will investigate the listener’s attitude towards advertising in podcasts, to find out what the listener considers about ad type and its placement in podcasts. This study was conducted through a combination of quantitative and qualitative methodology. To examine advertising patterns in Swedish podcasts, a quantitative method was applied, and podcasts on iTunes top ten were studied for six weeks. All podcasts were analyzed and documented and then compared with the results from McGowan's study (2010), since this one is the latest. The result showed that the bookend effect also exists in Swedish podcasts, however it appears more in US podcasts. How the advertisement is performed is also similar to the US podcasts, for example, "We’re this week sponsored by..." is similar to "Support for this podcast comes from...". Other advertising patterns that can be applied to Swedish podcasts are selfsufficient advertisements and recurring sponsors. To investigate the listener’s attitude towards podcast advertising, a qualitative method was used in the form of individual interviews. Respondents listened to a selection of advertisements from the top ten on iTunes, and was then interviewed about the advertisements. It was found that advertising is disturbing regardless of its type and placement. Sponsorship, when the program leader speaks, is preferred over traditional advertising. It is also preferred that the advertisement is placed in the beginning of a podcast, but sponsorship can make advertising placed in the middle of a podcast ok, because it can feel less interrupting with sponsorship compared to traditional advertisement.
89

Enhancing the openScope ADS-B Attack Simulator : Developing the openScope Attack Simulator to Meet Future Demand / Vidareutveckling av openScope-attack-simulatorn för att mötaframtida behov

Svensson Magnusson, Jon, Ulander, Zebastian January 2024 (has links)
No description available.
90

Anúncios Orgânicos e Patrocinados: estudo sobre intenção de compra online e comportamento visual / Organic and Sponsored Ads: online purchase intent and visual behavior study

Souza, Marina Teixeira de 07 December 2017 (has links)
A propaganda em sites de pesquisa utilizando anúncios orgânicos e patrocinados corresponde a uma estratégia de Marketing que propicia a interação entre empresas e seu público alvo a partir da utilização de palavras-chave ao efetuar a pesquisa online, dessa forma, os sites de pesquisa agem como intermediários entre necessidades dos consumidores e o grande número de informações disponíveis nas páginas da web. Assim, este estudo tem como objetivo verificar como é a relação entre atenção aos anúncios orgânicos e patrocinados e tipos de comportamento visual acerca da intenção de compra online. Foi realizada uma revisão da literatura sobre os Canais de Comunicação Online, Anúncios Orgânicos e Patrocinados bem como a utilização e eficácia desses tipos de anúncios, também foi abordado sobre a Intenção de Compra Online, Tipos de Comportamento Visual e, por fim, foi traçada a relação entre esses fatores. Na sequência, a partir da coleta de dados primária realizada com 100 estudantes da Faculdade de Administração, Economia e Contabilidade de Ribeirão Preto (FEA-RP/USP) - foi realizado um estudo quantitativo e descritivo utilizando o equipamento eye-tracking seguido da aplicação de um questionário. Utilizou-se a técnica estatística de Regressão Logística com Efeito Aleatório, que permite verificar o comportamento de um indivíduo em cenários diferentes e atender aos objetivos do estudo. A partir da análise, foi possível verificar que os indivíduos têm maior tendência a optar por Anúncios Patrocinados dos sites de pesquisa e que esse fato está positivamente relacionado à atenção visual e independe do tipo do Comportamento Visual que possui. Esses resultados fornecem informações relevantes acerca de apresentação de anúncios em sites de pesquisa, além de proporcionar reflexões teóricas para pesquisas nessa área / Advertising on search sites using organic and sponsored ads corresponds to a Marketing strategy that allows the interaction between companies and their target audience from the use of keywords when doing online search, in this way, the search sites act as intermediary consumer needs and the large number of information available on web pages. Thus, this study aims to verify how the relationship between attention in organic and sponsored ads and types of visual behavior about the intention to buy online. A review of the literature on Online Communication Channels, Organic and Sponsored Ads as well as the use and effectiveness of these types of ads was also made on Online Intention, Types of Visual Behavior and, finally, relationship between these factors. A quantitative and descriptive study was carried out using the eye-tracking equipment, followed by the application of the results obtained from the primary data collection with 100 students from the - School of Economics, Administration and Accounting of Ribeirao Preto (FEA-RP/USP) - a quantitative and descriptive study was performed using eye-tracking equipment followed by the application of a questionnaire. The statistical technique of Logistic Regression with Random Effect was used, which allows to verify the behavior of people in different scenarios and to meet the objectives of the study. From the analysis, it was possible to verify that the individuals have a greater tendency to choose Sponsored Ads of the research sites and this fact is positively related to the visual attention and independent of the type of Visual Behavior. These results provide relevant information about the display of ads on search sites, as well as provide theoretical insights for searches in this area

Page generated in 0.0289 seconds