The GERDA experiment searches for the neutrinoless double beta (0𝜈𝛽𝛽) decay of Ge-76. The observation of this decay would prove the Majorana character of the neutrino, i.e. that it is its own antiparticle. This would clarify the question which neutrino mass ordering is realized in nature and give a hint of the effective Majorana neutrino mass. Furthermore, the existence of the 0𝜈𝛽𝛽 decay would imply the violation of lepton number conservation which is a key feature in some theories explaining the asymmetry of matter and antimatter in the universe. The effective Majorana neutrino mass is connected with the half life of the 0𝜈𝛽𝛽 decay via a nuclear matrix element (NME), which is predicted by various theoretical models that are afflicted by large uncertainties. The accuracy of the different NMEs and their internal model assumptions can be increased by considering experimental investigations. While the NMEs for the 0𝜈𝛽𝛽 decay and the neutrino accompanied double beta (2𝜈𝛽𝛽) decay are numerically different, they rely on similar model assumptions. Thus, experimental constraints can be given by the 2𝜈𝛽𝛽 decay into the ground state, which has been already measured by GERDA with unprecedented precision for Ge-76, but also by the investigation of the 2𝜈𝛽𝛽 decay into excited states, which has not yet been observed for Ge-76. GERDA operates enriched germanium detectors in liquid argon (LAr) which serves as an additional background veto using the scintillation light that is created when energy is deposited in LAr. The signal signature of the decay into excited states can be enhanced with the application of the LAr veto, however, for that the efficiency of the LAr veto needs to be determined. One of the key parameters of the LAr efficiency is the attenuation of the scintillation light in LAr, which is dependent on the impurity composition and concentration in LAr. Therefore, the attenuation length of the scintillation light in LAr has been measured in GERDA with a dedicated setup in the course of this work. The analysis of the acquired data required intense computer simulations in order to describe the background for the measurement sufficiently. This also involved the measurement of the steel reflectivity in the visible and the UV region, where LAr scintillates. Therewith, the search for excited states has been performed in this work for the data accumulated in GERDA Phase I, Phase II and Phase II+ including the LAr veto for the latter two data sets. New limits have been set on the investigated excited states decay modes and some of the corresponding theoretical half life predictions could be disfavored, i.e. the underlying NMEs models can be constrained. The successor experiment LEGEND will continue searching for the 0𝜈𝛽𝛽 decay of Ge-76 using more germanium detectors together with an improved LAr veto. The investigation of the decay of Ge-76 into excited states will also be further pursued in LEGEND.

<div>Driving safety is a very important topic in vehicle development. One of the biggest threat of driving safety is road departure. Many vehicle active safety technologies have been developed to warn and mitigate road departure in recent years. In order to evaluate the performance of road departure warning and mitigation technologies, the standard testing environment need to be developed. The testing environment shall be standardized to provide consistent and repeatable features in various locations worldwide and in various seasons. The testing environment should also be safe to the vehicle under test in case the safety features do not function well. Therefore, soft, durable and reusable surrogates of roadside objects need to be used. Meanwhile, all surrogates should have the same representative characteristics of real roadside objects to different automotive sensors (e.g. radar, LIDAR and camera). This thesis describes the study on identifying the radar characteristics of common roadside objects, metal guardrail, grass, and concrete divider, and the development of the required radar characteristics of surrogate objects. The whole process is divided into two steps. The first step is to find the proper methods to measure the radar properties of those three roadside objects. The measurement result of each roadside object will be used as the requirement for making its surrogate. The second step is to create the material for developing the surrogate of each roadside object. In the experimental results demonstrate that all three surrogates satisfy their radar characteristics requirements.</div>

<p></p><p>The study deals with one of the critical aspects of the Road Departure Mitigation System. The first part of the study finds out what all color combinations and patterns represent the US roadside curbs, what should be the range of Radar Reflectivity values, and LiDAR Reflectance bounds that a surrogate curb should satisfy. The later part of the thesis illustrates methods and steps on how to mimic the extracted properties, design a surrogate curb as per federal standards, and then develop a surrogate curb.</p><br><p></p>

This project evaluates the ability of terahertz (THz) radiation to differentiate cancerous from non-cancerous human breast lumpectomy and mastectomy tissue. This is done by aiming a narrow-band THz beam at medical samples and measuring reflected power. THz images of specimens from Breast Conservation Surgery (BCS) were created using a gas laser source and mechanical scanning. The design and characterization of this system is discussed in detail. The images were correlated with optical histological micrographs of the same specimens and discrimination values of more than 70% were found for five of the six samples using Receiver Operating Characteristic (ROC) analysis.

Denna studie syftar till att bidra med kunskap om de förändringsprocesser som kontorsarbetande medarbetare fått erfarenhet av och upplevt vid distansarbete och vid återgång till den fysiska arbetsplatsen i samband med Covid-19 pandemin. Mezirows teori om transformativt lärande användes som teoretiskt perspektiv för studien och användes som tolkningsredskap för att besvara vilka faktorer som påverkat distansarbete och återgång till den fysiska arbetsplatsen och vilka erfarenheter medarbetare upplevt vid dessa förändringsprocesser i samband med Covid-19 pandemin. Studien baseras på åtta intervjuer med kontorsarbetande medarbetare där samtliga har erfarenhet av att till största del arbetat på distans under Covid-19 pandemin. Studien visade att det upplevda distansarbetet och återgången till den fysiska arbetsplatsen bidragit med erfarenheter. Resultatet visade att flexibiliteten vid distansarbete upplevs som den mest fördelaktiga faktorn samtidigt som tekniken är den faktor som ställer till mest problem. Dessutom framkommer saknaden av kollegorna och upplevd isolering som en av de främst utmanande faktorerna vid distansarbete och att få träffa sina kollegor igen upplevs vara den mest positiva faktorn vid återgången till den fysiska arbetsplatsen. De främsta utmaningarna med att komma tillbaka till den fysiska arbetsplatsen är både de störningsmoment som kontorsmiljön innebar och att behöva mötas i verkligheten och inte längre sitta trygg bakom en skärm. Slutligen visar studiens resultat att erfarenheterna från de upplevda förändringsprocesserna gällande arbetssituationen under Covid-19 pandemin resulterat i ett önskemål om att i framtiden arbeta utifrån en hybrid arbetsmodell som inkluderar både distansarbete och att arbeta på den fysiska arbetsplatsen. / This study aims to contribute with knowledge about the transformation process experienced by office working employees both during teleworking and returning to the physical workplace due to the Covid-19 pandemic. Based on Mezirow's theory of transformative learning, this study aims to answer what influencing factors and experiences employees experienced in transformation processes due to the Covid-19 pandemic. The study is based on eight interviews with office working employees who were mostly teleworking during the Covid-19 pandemic. This study shows that both teleworking and the return to the physical workplace contributed with experiences and the results show that the perceived flexibility in teleworking was the main positive factor, while technology was the most problematic. In addition, the lack of colleagues and perceived isolation emerges as the main challenges in teleworking and meeting their colleagues again was considered the best thing about returning to the physical workplace. The main challenges in returning to the physical workplace were both the disturbances that the office environment entailed and the challenge of now facing people in real life. Finally, the results of the study show that the experience from the perceived transformation processes regarding the work situation during the Covid-19 pandemic, has resulted in a desire for a hybrid working model in the future that includes both teleworking and working in the physical workplace.

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<p> It has been hypothesized that some measurable properties of $Z_{DR}$ arcs in supercells may change in the minutes prior to tornadogenesis and tornadogenesis failure, and that $Z_{DR}$ arc area will change with SRH and can be used as a real-time proxy to estimate SRH. Output form the Cloud Model 1 (CM1) along with a polarimetric emulator is used to simulate $Z_{DR}$ arcs in 9 tornadic and 9 non-tornadic supercells. A random forest algorithm is used to automatically identify the $Z_{DR}$ arcs. Finally the inflow sector SRH is calculated at times when $Z_{DR}$ arcs are identified. To analyze the change in intensity and area a comparison between the average $Z_{DR}$ value inside and outside of the arc, as well as the spatial size of the arc and storm was done. Model calculated SRH is then compared to these metrics.</p> <p> </p> <p> It has also been observed that hail fallout complicates the automatic identification of $Z_{DR}$ arcs. In this study, three experiments are run where the simulated $Z_{DR}$ arcs are produced. One using all categories of hydrometeors, one where wet growth and melting of hail is excluded, and one excluding the contribution to $Z_{DR}$ from the hail hydrometeor category. The same analysis as above is repeated for all three experiments. Finally observed $Z_{DR}$ arcs are analyzed to see if these results are applicable to the real world. </p>

Nanometric thin films are used widely throughout various industries and for various applications. Metallic thin films, specifically, are relied upon extensively in the microelectronics industry, among others. For example, alloy thin films are being investigated for CMOS applications, tungsten films find uses as contacts and diffusion barriers, and copper is used often as interconnect material. Appropriate metrology methods must therefore be used to characterize the physical properties of these films. Xray scattering experiments are well suited for the investigation of nano-scaled systems, and are the focus of this doctoral dissertation. Emphasis is placed on (1) phase identification of polycrystalline thin films, (2) the evaluation of the grain size and microstrain of metallic thin films by line profile analysis, and (3) the study of morphological evolution in solid/solid interfaces. To illustrate the continued relevance of x-ray diffraction for phase identification of simple binary alloy systems, Pt-Ru thin films, spanning the compositional range from pure Pt to pure Ru were investigated. In these experiments, a meta-stable extension of the HCP phase is observed in which the steepest change in the electronic work function coincides with a rapid change in the c/a ratio of the HCP phase. For grain size and microstrain analysis, established line profile methods are discussed in terms of Cu and W thin film analysis. Grain sizes obtained by x-ray diffraction are compared to transmission electron microscopy based analyses. Significant discrepancies between x-ray and electron microscopy are attributed to sub-grain misorientations arising from dislocation core spreading at the film/substrate interface. A novel "residual" full width half max parameter is introduced for examining the iv contribution of strain to x-ray peak broadening. The residual width is subsequently used to propose an empirical method of line profile analysis for thin films on substrates. X-ray reflectivity was used to study the evolution of interface roughness with annealing for a series of Cu thin films that were encapsulated in both SiO2 and Ta/SiO2. While all samples follow similar growth dynamics, notable differences in the roughness evolution with high temperature ex-situ annealing were observed. The annealing resulted in a smoothing of only one interface for the SiO2 encapsulated films, while neither interface of the Ta/SiO2 encapsulated films evolved significantly. The fact that only the upper Cu/SiO2 interface evolves is attributed to mechanical pinning of the lower interface to the rigid substrate. The lack of evolution of the Cu/Ta/SiO2 interface is consistent with the lower diffusivity expected of Cu in a Cu/Ta interface as compared to that in a Cu/SiO2 interface. The smoothing of the upper Cu/SiO2 interface qualitatively follows that expected for capillarity driven surface diffusion but with notable quantitative deviation.

No description available.

No description available.