京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22756号 / 工博第4755号 / 新制||工||1744(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 細田 尚, 教授 戸田 圭一, 准教授 音田 慎一郎 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(理学) / 甲第22986号 / 理博第4663号 / 新制||理||1669(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 松田 祐司, 教授 石田 憲二, 准教授 笠原 裕一 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Superradiance is an enhanced decay of an excited system of emitters resulting from their mutual coupling. This thesis is focused on superradiance of the emitters coupled via their interaction with a plasmonic nanoparticle. So-called plasmon-mediated superradiance results in even stronger enhancement of the decay rate as the nanoparticle serves as an additional decay chanel. We have developed a quantum model of the system of emitters coupled to a plasmonic nanoparticle, which allows us to differentiate between a pure dephasing and decay processes. We show that the pure dephasing can destroy the cooperative effect leading to superradiance. Furthermore, we have studied how the direct mutual coupling between emitters affects time evolution of the system in dependence on its configuration, and we show conditions when a decay of the system is dramatically decreased by direct coupling.

In the U.S., Black mothers experience fetal and infant mortality at alarming rates when compared to White and Latina mothers (Gregory, Drake, & Martin, 2018). The intent of this study was to examine perinatal loss among Black American women and to expand understanding of how the Strong Black Woman (SBW) ideology influences bereavement. Data were gathered from (N=109) Black American bereaved mothers. It was predicted that endorsement of differing aspects of the SBW would moderate the relationship between perinatal grief and psychosocial outcomes (i.e., depression and post-traumatic growth). Regression analyses, alongside a bootstrapping procedure via PROCESS (Hayes, 2017), were used to evaluate the moderation models. Results yielded a model of perinatal bereavement among Black American mothers. In particular, reliance on spirituality moderated the relationship between perinatal grief and depression, while the obligation to manifest strength moderated the relation between perinatal grief and posttraumatic growth (PTG). Neither moderated moderation model was significant. The model provided significant implications for clinical practice and intervention.

Title: U in metastable systems: structure, magnetism, and superconductivity Author: Volodymyr Buturlim Department / Institute: Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University Supervisor of the doctoral thesis: Doc. RNDr. Ladislav Havela, CSc., Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Prague, The Czech Republic Abstract: This thesis presents studies of U-Nb and U-Ti alloys and hydrides synthesized via different technological paths. Investigation of the microstructure of the alloys with different concentrations of Ti (Nb) allowed to find the optimum setting for stabilization of the metastable bcc U allotrope. Ultra-fast cooling accompanied by alloying leads to retention of materials with high degree of atomic disorder apparent from the studies of their transport properties. The alloys exhibit a weakly paramagnetic ground state and low-temperature superconductivity, the critical temperature of which has only moderate variations with Ti (Nb) concentrations and which has very high upper critical fields. Interaction with hydrogen allows to stabilize two distinctive forms of hydride: β-UH3 and UTi2Hx. β-UH3 alloyed by Ti (Nb) orders ferromagnetically with transition temperatures exceeding 170 K, weakly influenced...

The dynamical Schwinger effect refers to the creation of electron-positron pairs by a time dependent, spatially homogeneous electric field. It probes the fundamentals of quantum electrodynamics and is sought to be verified with upcoming high-intensity laser installations. In the dynamically assisted Schwinger effect, the pair yield is increased by orders of magnitude through the combination of fields of different field strength and frequency scales. In this thesis we, investigate both processes in the framework of a quantum kinetic equation. We are especially interested in what amplification factors can be achieved by the assisting field and whether intermediately large mode occupation numbers have a physical significance and could serve as a verification of the Schwinger effect. For the latter goal, we couple our system to a quantized radiation field that serves as a secondary (photon) probe and study its spectrum, as the afterglow of the dynamical Schwinger effect. / Als dynamischen Schwingereffekt bezeichnet man die Erzeugung von Elektron-Positron-Paaren durch ein zeitabhängiges, räumlich homogenes elektrisches Feld. Er dient zur Untersuchung der Grundlagen der Quantenelektrodynamik und es wird versucht, ihn an zukünftigen Hochintensitäts-Laseranlagen zu verifizieren. Bei dem dynamisch assistierten Schwingereffekt wird die Paarausbeute durch eine Kombination von Feldern mit unterschiedlichen Feldstärken- und Frequenzskalen um mehrere Größenordnungen erhöht. In dieser Dissertation untersuchen wir beide Prozesse im Rahmen einer quantenkinetischen Gleichung. Wir interessieren uns besonders dafür, welche Verstärkungsfaktoren durch das assistierende Feld erreicht werden können und ob intermediär große Modenbesetzungszahlen physikalische Signifikanz haben und als Verifizierung des Schwingereffekts dienen können. Für zweiteres Ziel koppeln wir unser System an ein quantisiertes Strahlungsfeld, das als sekundäres (Photonen-) Signal dient, und untersuchen dessen Spektrum, das Nachglühen des dynamischen Schwingereffekts.

1 Abstract Legal regulation of payments The thesis deals with the topic of legal regulation of the payment transactions, which is an indispensable part of the economic life of each of us today. The right setting of the operation of the payment system ensures and directly influences the efficiency of economic exchange, whether at the national or international level, in cash or non-cash forms. Not only because of the importance of economic exchange, the thesis pays the main attention to the regulation of funds, i.e. of banknotes and coins, scriptural money as well as electronic money. The thesis aims to introduce the legal regulation of funds and the related use of modern electronic payment instruments, such as payment cards, internet banking, mobile banking and electronic wallets. In order to achieve the defined objective, the thesis discusses the amendment to Act No. 370/2017 Coll., On Payments, and the PSD2 Directive in the context of other legal regulations and financial market rules. The thesis is divided into four chapters that present the issues in question and whose subsequent outputs are summarized in the conclusion. The first chapter acquaints the reader with the definition of the payments, its historical development in the Czech Republic and its typology according to the basic distinguishing...

Nowadays weak single-factor authentication mechanisms like passwords or passphrases are commonly used. Static passwords are easy to use, just remember them in mind. However it has many security weaknesses and even strong passwords are not strong enough. For example, strong secrets are difficult to remember, and people tend to share authentication credentials across systems, which reduce the overall security tremendously. Thus, for security sensitive environment we need strong multi-factors authentication. Smart card based certificate strong authentication solution can be used as a replacement for standard password-based schemes. And also a large existing base of deployed smart cards used to provide authentication in other areas can be reused to reduce costs significantly. This master thesis presents a study of how to implement certificate-based strong authentication on mobile devices using PIV smart card. It proposes a strong authentication protocol based on FIPS 201 Personal Identity verification standard, and FIPS 196 entity strong authentication protocol scheme, and describes the implementation of a mobile security application developed on iOS system using a smart card reader. Our solution can provide high level of security services for mobile applications, and can easily protect their confidentiality, integrity and authenticity.

The advancement of ICT in a variety of sectors helped in improving the time consuming and rigid service into fast and flexible service that is closer to the reach of individuals. For instance, mobile applications have evolved in different sectors such as healthcare patient support, geographic mapping and positioning, banking, e-commerce payment services and others. This study focuses on one of the most sensitive applications, which is mobile payment. Mobile payment system being one of the widely expanding mobile services, it has security concerns that prevented its wide acceptance. Some of the main security services given prior attention in mobile payment are issues of privacy, authentication and confidentiality. The research concentrates on the strong authentication of a mobile client to its server, securing the credit card* information and use of mobile card reader while making payments that enable customers to protect privacy of financial credentials. The strong authentication mechanism mainly follows the NIST standard publications namely, FIPS PUB 201 and FIPS 196; which are standards on Entity Authentication using public key cryptography and PKI credential storage Personal Identity Verification (PIV) card respectively. The proposed secure Credit Card Information (CCI) storage is in a secure element in order to prevent tampering of stored data. The secure element options are microSD, UICC, Smartcard (together with digital certificate and service ticket). During making payments, the payment information encrypted using a shared key is securely sent to payment server. A demo mobile application as proof of concept was implemented in a simulated lab (KTH SecLab), which has all the necessary infrastructure setup (servers, card reader) for testing the proposed solution. The paper was able to proof the concept of secure payment by enhancing the authentication, confidentiality and privacy of payment information. However, the demo for Strong Authentication did not completely succeed as expected due to unexpected bugs in the early version of card reader SDK.

Water is essential element for human survival but unstainable development practices and short term economic benefits are responsible for water scarcity in many areas around the world. Climate change is aggravating the risk with distribution and water availability. Agriculture is a sector highly dependent on water. The livelihood of a vast population in the world depends on not only agriculture, but also forestry, wetlands and fisheries and land use which, in turn, are strongly influenced by water based ecosystems that depend on monsoon rains. India is a global agricultural powerhouse. It is the world’s largest producer of milk, pulses, and spices as well as the largest area under wheat, rice and cotton. But increasing water scarcity in India is affecting agricultural sector, hence affecting socio- economic conditions of poor Indian farmers. In some pockets of the country, attempts have been made during the last few decades to manage the scarce water resources more efficiently and govern them more wisely, so that agriculture as the main economic backbone of the local communities can be sustainably supported. Ralegan Siddhi is one such outstanding case where the rainwater harvested through local interventions has enabled sustainable development of the entire community. The village stands out as an oasis in the desert. The aim of the study is to understand how water has been governed in Ralegan Siddhi to enable sustainable agriculture and hence sustainable development of the community. Ultimately, the study is foreseen to help improve the farmers’ situation in water scarce areas in India and elsewhere by sharing this study report based on Ralegan Siddhi’s water governance practices with other researchers as well as concerned agencies and actors.