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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.
1

Big browser is watching you : How Information Privacy Concerns and Involvement affect Purchase Intentions in Online Personalized Advertising

Karlsson, Malin, Karlsson, Sandra, Malmberg, Amanda January 2015 (has links)
Authors: Malin Karlsson, Sandra Karlsson, Amanda Malmberg Tutor: Dr. Setayesh Sattari Examiner: Prof. Anders Pehrsson Background: Consumers increasingly purchase products online due to the widespread use of the Internet. The decision for consumers to purchase online is predicted by their purchase intentions, which in turn is affected by their information privacy concerns. There is a lack of research on IPC and purchase intentions in the context of online personalized advertising. Purpose: To extend the understanding of purchase intentions considering information privacy concerns and involvement in the context of online personalized advertising. Methodology: A survey in form of a questionnaire was conducted in order to gather the information necessary to be able to analyse the relationship between IPC and purchase intentions in the context of online personalized advertising. The sample consists of 18-70 year olds from cities in southern Sweden. Conclusion: Conclusions drawn in this thesis is that when applied in the context of online personalized advertising, there is no significant relationship between IPC and purchase intentions. However, involvement is suggested as having a positive relationship to purchase intentions, as well as a positive moderating effect on the relationship between IPC and purchase intention in the context of online personalized advertising. Keywords: Purchase intentions, Information privacy concerns (IPC), Online personalized advertising, Involvement.
2

Improving Operating System Security, Reliability, and Performance through Intra-Unikernel Isolation, Asynchronous Out-of-kernel IPC, and Advanced System Servers

Sung, Mincheol 28 March 2023 (has links)
Computer systems are vulnerable to security exploits, and the security of the operating system (OS) is crucial as it is often a trusted entity that applications rely on. Traditional OSs have a monolithic design where all components are executed in a single privilege layer, but this design is increasingly inadequate as OS code sizes have become larger and expose a large attack surface. Microkernel OSs and multiserver OSs improve security and reliability through isolation, but they come at a performance cost due to crossing privilege layers through IPCs, system calls, and mode switches. Library OSs, on the other hand, implement kernel components as libraries which avoids crossing privilege layers in performance-critical paths and thereby improves performance. Unikernels are a specialized form of library OSs that consist of a single application compiled with the necessary kernel components, and execute in a single address space, usually atop a hypervisor for strong isolation. Unikernels have recently gained popularity in various application domains due to their better performance and security. Although unikernels offer strong isolation between each instance due to virtualization, there is no isolation within a unikernel. Since the model eliminates the traditional separation between kernel and user parts of the address space, the subversion of a kernel or application component will result in the subversion of the entire unikernel. Thus, a unikernel must be viewed as a single unit of trust, reducing security. The dissertation's first contribution is intra-unikernel isolation: we use Intel's Memory Protection Keys (MPK) primitive to provide per-thread permission control over groups of virtual memory pages within a unikernel's single address space, allowing different areas of the address space to be isolated from each other. We implement our mechanisms in RustyHermit, a unikernel written in Rust. Our evaluations show that the mechanisms have low overhead and retain unikernel's low system call latency property: 0.6% slowdown on applications including memory/compute intensive benchmarks as well as micro-benchmarks. Multiserver OS, a type of microkernel OS, has high parallelism potential due to its inherent compartmentalization. However, the model suffers from inferior performance. This is due to inter-process communication (IPC) client-server crossings that require context switches for single-core systems, which are more expensive than traditional system calls; on multi-core systems (now ubiquitous), they have poor resource utilization. The dissertation's second contribution is Aoki, a new approach to IPC design for microkernel OSs. Aoki incorporates non-blocking concurrency techniques to eliminate in-kernel blocking synchronization which causes performance challenges for state-of-the-art microkernels. Aoki's non-blocking (i.e., lock-free and wait-free) IPC design not only improves performance and scalability, but also enhances reliability by preventing thread starvation. In a multiserver OS setting, the design also enables the reconnection of stateful servers after failure without loss of IPC states. Aoki solves two problems that have plagued previous microkernel IPC designs: reducing excessive transitions between user and kernel modes and enabling efficient recovery from failures. We implement Aoki in the state-of-the-art seL4 microkernel. Results from our experiments show that Aoki outperforms the baseline seL4 in both fastpath IPC and cross-core IPC, with improvements of 2.4x and 20x, respectively. The Aoki IPC design enables the design of system servers for multiserver OSs with higher performance and reliability. The dissertation's third and final contribution is the design of a fault-tolerant storage server and a copy-free file system server. We build both servers using NetBSD OS's rumprun unikernel, which provides robust isolation through hardware virtualization, and is capable of handling a wide range of storage devices including NVMe. Both servers communicate with client applications using Aoki's IPC design, which yields scalable IPC. In the case of the storage server, the IPC also enables the server to transparently recover from server failures and reconnect to client applications, with no loss of IPC state and no significant overhead. In the copy-free file system server's design, applications grant the server direct memory access to file I/O data buffers for high performance. The performance problems solved in the server designs have challenged all prior multiserver/microkernel OSs. Our evaluations show that both servers have a performance comparable to Linux and the rumprun baseline. / Doctor of Philosophy / Computer security is extremely important, especially when it comes to the operating system (OS) – the foundation upon which all applications execute. Traditional OSs adopt a monolithic design in which all of their components execute at a single privilege level (for achieving high performance). However, this design degrades security as the vulnerability of a single component can be exploited to compromise the entire system. The problem is exacerbated when the OS codebase becomes large, as is the current trend. To overcome this security challenge, researchers have developed alternative OS models such as microkernels, multiserver OSs, library OSs, and recently, unikernels. The unikernel model has recently gained popularity in application domains such as cloud computing, the internet of things (IoT), and high-performance computing due to its improved security and performance. In this model, a single application is compiled together with its necessary OS components to produce a single, small executable image. Unikernels execute atop a hypervisor, a software layer that provides strong isolation between unikernels, usually by leveraging special hardware instructions. Both ideas improve security. The dissertation's first contribution improves the security of unikernels by enabling isolation within a unikernel. This allows different components of a unikernel (e.g., safe code, unsafe code, kernel code, user code) to be isolated from each other. Thus, the vulnerability of a single component cannot be exploited to compromise the entire system. We used Intel's Memory Protection Keys (MPK), a hardware feature of Intel CPUs, to achieve this isolation. Our implementation of the technique and experimental evaluations revealed that the technique has low overhead and high performance. The dissertation's second contribution improves the performance of multiserver OSs. This OS model has excellent potential for parallelization, but its performance is hindered by slow communication between applications and OS subsystems (which are programmed as clients and servers, respectively). We develop Aoki, an Inter-Process Communication (IPC) technique that enables faster and more reliable communication between clients and servers in multiserver OSs. Our implementation of Aoki in the state-of-the-art seL4 microkernel and evaluations reveal that the technique improves IPC latency over seL4's by as much as two orders of magnitude. The dissertation's third and final contribution is the design of two servers for multiserver OSs: a storage server and a file system server. The servers are built as unikernels running atop the Xen hypervisor and are powered by Aoki's IPC mechanism for communication between the servers and applications. The storage server is designed to recover its state after a failure with no loss of data and little overhead, and the file system server is designed to communicate with applications with little overhead. Our evaluations show that both servers achieve their design goals: they have comparable performance to that of state-of-the-art high-performance OSes such as Linux.
3

Der Einfluss von transkranieller Gleichstromstimulation auf das perzeptuelle Lernen degradierter Sprache

Schnitzler, Tim 22 May 2015 (has links) (PDF)
Cochlea-Implantate sind Neuroprothesen, die es Gehörlosen ermöglichen, Zugang zu auditiver Information wieder zu erlangen. Allerdings ist das resultierende Signal stark verzerrt bzw. degradiert und eine erfolgreiche Adaptation oft unvollständig. Das Verständnis zugrundeliegender perzeptueller Lernprozesse ist somit von enormer klinischer Bedeutung. Perzeptuelles Lernen degradierter Sprache lässt sich mittels Noise-Vokodierung bei Hörgesunden simulieren. In Bildgebungsstudien konnte anhand funktioneller Magnetresonanztomographie gezeigt werden, dass perzeptuelles Lernen degradierter Sprache mit einer Aktivitätssteigerung im linken inferior frontal gyrus (IFG) und linken inferior parietal cortex (IPC) assoziiert war. Die vorliegende Studie untersucht den Einfluss von fazilitierender, nicht-invasiver Hirnstromstimulation (anodale transkranielle Gleichstromstimulation, tDCS) über dem linken IFG und linken IPC auf das perzeptuelle Lernen {\\itshape{Noise}}-vokodierter Sprache. Die Probanden trainierten die Diskrimination von Minimal- (\"Tisch\"- \"Fisch\") und identen (\"Tisch\"- \"Tisch\") Wortpaaren, während der erste Stimulus akustisch degradiert, der zweite in geschriebener Form präsentiert wurden. Vor und nach dem Training wurden die trainierten Stimuli und eine gleiche Anzahl untrainierter Stimuli präsentiert. Perzeptuelles Lernen wurde in unserer Studie als eine Verbesserung der Diskriminationsleistung untrainierter Wortpaare operationalisiert. Zudem wurde vor und nach dem Training ein Elektroenzephalogramm abgeleitet. Auf elektrophysiologischer Ebene wurde der Einfluss des Lernvorgangs und der tDCS auf die N400 untersucht, welche mit der Verarbeitung lexiko-semantischer Informationen assoziiert ist. Unsere Ergebnisse zeigen, dass eine anodale tDCS über dem linken IFG perzeptuelles Lernen stark degradierter Sprache fazilitierte, während bei einer Placebo- bzw. einer Stimulation über dem linken IPC kein perzeptuelles Lernen stattfand.
4

Studenters integritetsoro kring hantering av personlig information : En kvalitativ studie inom e-bank, e-handel och e-hälsa / Students privacy concern regarding management of personal information : A qualitative study within e-bank, e-commerce and e-health

Nilsson, Philip, Jonson, Joel January 2022 (has links)
Insamling av personlig information utförs av företag i kommersiella syften och används till att skapa profiler och beteendemönster. Utnyttjandet av användares personliga information har upprepande gånger lett till konflikter där människors oro över sin personliga integritet har belysts. Detta har resulterat i skapandet av förordningar som GDPR, California Consumer Privacy Act och ett flertal nationella lagar som syftar till att stärka och skydda individers personuppgifter. Tidigare statistiska undersökningar har visat att studenter är en population som upplever oro över personlig datainsamling. Därav kommer urvalet för denna studie fokusera på studenter.  Syftet med studien är att skapa en förståelse över när en student känner oro i att lämna ifrån sig personlig information. Tidigare forskning visar på att frågor inom integritetsoro är djupt förknippad med en kontext och betydelsen av att placera situationen i ett sammanhang. Domänområdena e-bank, e-handel och e-hälsa har därför valts ut att undersökas i denna studie på grund av deras känsliga samband till integritetsoro men även dess påtagliga relevans inom IS-området.  Studiens resultat bekräftar att integritetsoro skiljer sig genom kontexter i viss mån men studien pekar även på tydliga samband. En oro över faktorn obehörig tillgång förekommer bland tre domäner, dock skiljer sig situationen åt i varje domän. Människors medvetenhet har visat sig vara oberoende av domän då studenter förstår att personlig information samlas in, men vet inte vad den används till. / Today’s companies use Personal data collection for commercial purposes and use it to create profiles and analyze behavior patterns. This abuse of users' personal information has repeatedly led to conflicts in which people's concerns about their privacy have been enlightened. This has resulted in the creation of several regulations such as the GDPR, the California Consumer Privacy Act and a number of national laws that strengthen and protect individuals' personal data. Previous statistical surveys have shown that students are a population that is concerned about personal data collection. Hence, the selected group for this study will be students.  The purpose of this study is to create an understanding of when a student is concerned about disclosing personal information. Previous research shows that privacy concerns are deeply associated with placing the situation in a context. The domain areas of ebanking, e-commerce and e-health have therefore been selected to be examined in this study due to their sensitive connection to privacy concerns but also its noticeable relevance within the IS-area.  The result of this study confirms that integrity concerns differ through contexts to some extent, however the result also shows that there are certain similarities. A concern about the factor improper access occurs among three domains, however, the situation differs in each domain. People's awareness has been shown to be independent by domain as students, regardless of the discussed domain, understand that personal information is collected, but do not know what it is used for.
5

Tamoxifeno no tratamento de leishmaniose: atividade em esquemas terapéuticos combinados e estudo do mecanismo de ação. / Tamoxifen in leishmaniasis treatment: activity in combined therapeutic schemes and study of mechanism of action.

Tronco, Cristiana de Melo Trinconi 04 December 2015 (has links)
A leishmaniose é uma doença parasitária de ampla distribuição, para a qual se dispõe de um limitado arsenal terapêutico. Trabalhos recentes mostraram que tamoxifeno é eficaz no tratamento de leishmaniose experimental. Nesse trabalho, avaliamos a terapia combinada de tamoxifeno com os fármacos utilizados atualmente no tratamento desta enfermidade. A interação entre os fármacos mostrou-se aditiva, tanto in vitro como in vivo. Em paralelo, analisamos os efeitos de tamoxifeno na biossíntese de esfingolipídios em Leishmania, sendo identificada a redução da síntese de fosfatidilinositol e inositolfosforil ceramida (IPC) e acúmulo de ceramida acilada. A redução na biossíntese de IPC não pode ser atribuída a redução no transporte de inositol, mas provavelmente está relacionada à inibição da enzima IPC sintase. Estes resultados indicam novas estratégias para superar as deficiências encontradas no tratamento de leishmaniose utilizando tamoxifeno, um fármaco clinicamente bem conhecido que exerce ações em múltiplos alvos em Leishmania. / Leishmaniasis is a parasitic disease with wide distribution and limited treatment. Recent reports demonstrate that tamoxifen is an effective drug for experimental leishmaniasis treatment. In this work, we evaluated the combined therapy of tamoxifen with current drugs used in leishmaniasis chemotherapy. The drug interaction was additive both, in vitro and in vivo. We also evaluated tamoxifen effect on in Leishmania sphingolipids biosynthesis. We found a reduction in phosphatidylinositol and inositol phosphorylceramide (IPC) synthesis and an accumulation of acilceramide. The reduction in IPC biosynthesis could not be assigned to the reduction observed in inositol transport, but probably is related to IPC synthase inhibition. These results show new strategies to circumvent shortcomings of leishmaniasis treatment using tamoxifen, a multitarget drug in Leishmania and widely used in the chemotherapy of breast cancer.
6

Composites fibres / matrice minérale : du matériau a la structure / Textile reinforced mineral matrix composites : from material to the structure

Promis, Geoffrey 05 February 2010 (has links)
Ce travail de recherche est axé sur le développement de composites à liant phosphatique et fibres de renfort en verre E pour diverses applications structurales en Génie Civil. Dans une première partie, un bilan bibliographique nous permet d’identifier les principaux facteurs aux différentes échelles (nano, micro, méso et macro) ayant une influence sur le comportement global de composites à matrice minérale. Dans un second temps, les propriétés mécaniques et physico-chimiques des constituants sont présentées. Nous développons une méthodologie spécifique de caractérisation en traction, en compression et en cisaillement. Le développement de procédures expérimentales particulières en compression et en cisaillement permet l’identification des lois de comportement et l’évaluation des seuils d’endommagement et charges de rupture. La prévision des différents termes de rigidité élastique des systèmes composites est évaluée à partir d’expressions reprenant les principes de base de la micromécanique des composites. L’analyse du comportement à rupture est abordée au plan mésoscopique en considérant deux critères de résistance en plasticité, anisotropie (Tsai-Wu) et en contrainte normale, de cisaillement (Mohr-Coulomb). La deuxième partie de la recherche est consacrée à l’étude d’éléments structuraux mettant en oeuvre les formulations pultrudés de ces systèmes composites. L’expérimentation de poutres, présentant un rapport de la hauteur de la section à la portée de la poutre compris entre 1/15 et 1/50, met en évidence des modes de rupture spécifiques confirmant les faibles caractéristiques du matériau vis-à-vis de l’effort tranchant, du cisaillement interlaminaire et de la décohésion fibre/matrice. L’optimisation de la conception et du dimensionnement des poutres se poursuit en considérant des modifications d’ordre technologique : modification des sections par addition d’entretoises, confinement des sections par tressage circonférentiel, application d’un confinement par stratification directe. Pour chaque type de structures, nous cherchons à définir les limites de validité des méthodes de dimensionnement usuelles en examinant plus particulièrement la conformité des hypothèses de calcul (Navier-Bernoulli, Saint Venant), la cohérence des équations d’équilibre au regard de la cinématique dans chaque section. Dans un second temps, nous considérons des développements intégrant les non linéarités de comportement ou des modèles d’équilibre de type force adaptés à la redistribution interne des efforts tranchants. / This PhD thesis focuses on the development of E-glass reinforced Inorganic Phosphate Cement (IPC) matrix composites for structural applications in Civil Engineering. First, a bibliographical review highlights the main parameters occurring at different scales (nano, micro, meso and macro) influencing the global behaviour of the composite. Mechanical and physico-chemical properties of the different components are presented, followed by a characterization methodology in tension, in compression and in shear. The development of specific experimental procedures in compression and in shear leads to the identification of the constitutive equations and to the assessment of the damage and failure thresholds. The prediction of the different terms of elastic stiffness is assessed using micromechanical expressions. The failure is analysed at the macroscopic scale considering two failure criteria: Tsai-Wu and Mohr-Coulomb. The second part of the study is devoted to the analysis of loadbearing elements in glass reinforced mineral matrix. The realised beams show a height-to-span ratio between 1/15 and 1/50. The experimentation highlights specific failure modes confirming the weak shear performance of the composite in terms of shear force, interlaminar shear and fibre/matrix decohesion. Some technological modifications allow the optimisation of the design: the use of internal reinforcing struts, external confinement by fiber braiding and external wrapping. For each type of structure, we define the validity limits of the usual design methods examining the design hypotheses (Navier-Bernoulli, Saint Venant) and the equilibrium equations in function of the kinematics. In a second time, we consider the development of a force equilibrium model integrating a non-linear behaviour adapted to the internal redistribution of the shear forces.
7

Tamoxifeno no tratamento de leishmaniose: atividade em esquemas terapéuticos combinados e estudo do mecanismo de ação. / Tamoxifen in leishmaniasis treatment: activity in combined therapeutic schemes and study of mechanism of action.

Cristiana de Melo Trinconi Tronco 04 December 2015 (has links)
A leishmaniose é uma doença parasitária de ampla distribuição, para a qual se dispõe de um limitado arsenal terapêutico. Trabalhos recentes mostraram que tamoxifeno é eficaz no tratamento de leishmaniose experimental. Nesse trabalho, avaliamos a terapia combinada de tamoxifeno com os fármacos utilizados atualmente no tratamento desta enfermidade. A interação entre os fármacos mostrou-se aditiva, tanto in vitro como in vivo. Em paralelo, analisamos os efeitos de tamoxifeno na biossíntese de esfingolipídios em Leishmania, sendo identificada a redução da síntese de fosfatidilinositol e inositolfosforil ceramida (IPC) e acúmulo de ceramida acilada. A redução na biossíntese de IPC não pode ser atribuída a redução no transporte de inositol, mas provavelmente está relacionada à inibição da enzima IPC sintase. Estes resultados indicam novas estratégias para superar as deficiências encontradas no tratamento de leishmaniose utilizando tamoxifeno, um fármaco clinicamente bem conhecido que exerce ações em múltiplos alvos em Leishmania. / Leishmaniasis is a parasitic disease with wide distribution and limited treatment. Recent reports demonstrate that tamoxifen is an effective drug for experimental leishmaniasis treatment. In this work, we evaluated the combined therapy of tamoxifen with current drugs used in leishmaniasis chemotherapy. The drug interaction was additive both, in vitro and in vivo. We also evaluated tamoxifen effect on in Leishmania sphingolipids biosynthesis. We found a reduction in phosphatidylinositol and inositol phosphorylceramide (IPC) synthesis and an accumulation of acilceramide. The reduction in IPC biosynthesis could not be assigned to the reduction observed in inositol transport, but probably is related to IPC synthase inhibition. These results show new strategies to circumvent shortcomings of leishmaniasis treatment using tamoxifen, a multitarget drug in Leishmania and widely used in the chemotherapy of breast cancer.
8

Analýza a optimalizace procesu výroby vývojových vzorků / Analyse and Optimise Production Process of Prototypes

Hamr, Tomáš January 2019 (has links)
This diploma thesis summarizes basic findings about issues of making development samples of PCB. The emphasis is especially on required quality which complies with mentioned norms. The theoretical section includes methodology for evaluating quality dismounted boards, assembling and soldering, parameters of components under different environmental circumstances. The practical part is carried out in cooperation with the department EEG in R&D Automotive Lighting Jihlava. It is dedicated to the design and the preparation of development samples where the quality is assessed according to given methodology from the theoretical part. PCB are analyzed by an X-ray, metallographic grinding and other methods. Recommendations are given and based on results for improvements.
9

Kontrola kvality pájeného spoje a Design of Experiments u strojního pájení vlnou / Solder Joint Quality Control and Design of Experiments in Wave Soldering

Smeliková, Lenka January 2014 (has links)
This master´s thesis deals with problems of wave soldering and application methods Design of Experiments for the new product production. Summarizes the basic knowledge of soldering technology, of solder alloys and Design of Experiments methods. Design of Experiments method has been applied to product to find the optimal for wave soldering setting.
10

Der Einfluss von transkranieller Gleichstromstimulation auf das perzeptuelle Lernen degradierter Sprache

Schnitzler, Tim 02 May 2015 (has links)
Cochlea-Implantate sind Neuroprothesen, die es Gehörlosen ermöglichen, Zugang zu auditiver Information wieder zu erlangen. Allerdings ist das resultierende Signal stark verzerrt bzw. degradiert und eine erfolgreiche Adaptation oft unvollständig. Das Verständnis zugrundeliegender perzeptueller Lernprozesse ist somit von enormer klinischer Bedeutung. Perzeptuelles Lernen degradierter Sprache lässt sich mittels Noise-Vokodierung bei Hörgesunden simulieren. In Bildgebungsstudien konnte anhand funktioneller Magnetresonanztomographie gezeigt werden, dass perzeptuelles Lernen degradierter Sprache mit einer Aktivitätssteigerung im linken inferior frontal gyrus (IFG) und linken inferior parietal cortex (IPC) assoziiert war. Die vorliegende Studie untersucht den Einfluss von fazilitierender, nicht-invasiver Hirnstromstimulation (anodale transkranielle Gleichstromstimulation, tDCS) über dem linken IFG und linken IPC auf das perzeptuelle Lernen {\\itshape{Noise}}-vokodierter Sprache. Die Probanden trainierten die Diskrimination von Minimal- (\"Tisch\"- \"Fisch\") und identen (\"Tisch\"- \"Tisch\") Wortpaaren, während der erste Stimulus akustisch degradiert, der zweite in geschriebener Form präsentiert wurden. Vor und nach dem Training wurden die trainierten Stimuli und eine gleiche Anzahl untrainierter Stimuli präsentiert. Perzeptuelles Lernen wurde in unserer Studie als eine Verbesserung der Diskriminationsleistung untrainierter Wortpaare operationalisiert. Zudem wurde vor und nach dem Training ein Elektroenzephalogramm abgeleitet. Auf elektrophysiologischer Ebene wurde der Einfluss des Lernvorgangs und der tDCS auf die N400 untersucht, welche mit der Verarbeitung lexiko-semantischer Informationen assoziiert ist. Unsere Ergebnisse zeigen, dass eine anodale tDCS über dem linken IFG perzeptuelles Lernen stark degradierter Sprache fazilitierte, während bei einer Placebo- bzw. einer Stimulation über dem linken IPC kein perzeptuelles Lernen stattfand.

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