This dissertation documents works on two projects, which are broadly related to photonic integration using III-V semiconductor platform for fiber-based optical communication. Our principal project aims to demonstrate continuous variable quantum key distribution (CV-QKD) with InP-based photonic integrated cir cuit at the 1550 nanometer of optical wavelength. CV QKD protocols, in which the key is encoded in the quadrature variables of light, has generated immense interest over the years because of its compatibility with the existing telecom infrastructure. In this thesis, we have proposed a design of a photonic inte grated circuit potentially capable of realizing this protocol with coherent states of light. From the practical perspective, we have basically designed an optical transmitter and an optical receiver capable of carrying out coherent communi cation via the optical fiber. Initially, we established a mathematical model of the transceiver system based on the optical transfer matrix of the foundry spe cific (Fraunhofer Heinrich Hertz Institute-Germany) building blocks. We have shown that our chip design is versatile in the sense that it can support multiple modulation schemes. Based on the mathematical model, we estimated the link budget to assess the feasibility of on-chip implementation of our protocol. Then we ran a circuit level simulation using the process design kit provided by our foundry to put our analysis on a better footing. The encouraging result from this step prompted us to generate the mask layout for our transceiver chips, which we eventually submitted to the foundry. The other project in the thesis grew out of a collaboration with one of our industry partners. The goal of the project is to enhance the performance of a distributed feedback laser emitting at the 1310 nanometer of optical wavelength by optimizing its design. To that end, we first derived the expression for transmission and reflection spectrum for the laser cavity. Those expressions contained parameters which needed to be obtained from the transverse and the longitudinal mode analysis of the laser. We performed the transverse mode analysis and the longitudinal mode analysis with commercially available numerical solvers. Those mode profiles critically depend on the grating physical parameters. Therefore by tweaking grating dimensions one can control the transmission characteristics of the laser.

The purpose of this study is to explore and interpret the different meanings and consequences of diversity and its associated practices for the police organization in Sweden. By highlighting possible discourses on the concept of diversity within the police organization and how the police organization presents the concept of diversity, based on that, contribute to an increased understanding of the police organization’s diversity work. Our study is based on a qualitative method, discourse analysis, which has helped us collect the empirical material. The purpose with discourse analysis is to interpret what is written, therefore this study is based on our own interpretations of the empirical material. The empirical material that consists of the police policy documents has in turn been analyzed based on Carol Bacchi’s “What’s the problem represented to be-approach” (WPR-approach) and the neo-institutional theory where concepts such as isomorphism and loosely coupled occur. When studying the police organization, the concept of diversity is seen to be common. The police highlights the importance of having diversity within their organization, which can be seen to have emerged over time. The result of this study indicates that the police organization works actively to make equal treatment a natural part of the organization today. This includes wanting to reflect society and they believe that diversity entails different skills which they want to utilize within the organization. The study also describes three different problem representations which we have identified in the empirical material. These problem representations have in turn helped us to highlight different discourses about the concept of diversity, which has contributed to an increased understanding of the police organization’s diversity work.

More efficiency heavy-duty vehicles are developed with higher range, updated electronic and mechanical parts. The fuel efficiency and pollution of carbon dioxide need to be lower to achieve new EU regulations. The global population increases with an increased number of heavy-duty vehicles. This, in turn, increases the emission. By taking the electrical and mechanical parts to the next step, the global emission problems can be massively reduced. Electrical machines are the next step towards a cleaner future. The main goal of this study to investigate the electrical machine’s insulation system. Thermo-mechanical stresses due to thermal cycling affect the electrical machines and its sub-components. By using a FEM application with simplified models of the electrical machine, results are obtained and discussed. Specifically, if 2D-models are sufficient enough to represent a 3D-model. How good different 2D-models can represent the 3D-model is compared and discussed in this study. A physical experimental analysis is done to verify and calibrate the FE-models. Which one of the less frequent higher amplitude or more frequent, lower amplitude thermal cycling affects the insulation system most is determined. The simulations could be done with either, coupled-temperature displacement analysis or sequentially coupled analysis. Coupled-temperature displacement is the fastest method to use in the simulation models. A 3D-model is the best way to describe an object and is therefore implemented. Two additional 2D-models are developed for faster computation and to investigate if the models can represent the three-dimensional geometry. All the models have specific boundary conditions to make the models more simplified. Sensitivity studies have been done to determine which parameter affects the induced thermo-mechanical stresses the most. A physical experimental setup is also implemented to validate and calibrate the simulation model. The result of the 3D-model is most accurate when simulating a three-dimensional object. Simulation results have shown that epoxy, one of the main components in the insulation system, is most critical in terms of reaching breakdown first, followed by paper insulation and copper coating. This is a typical result of all three simulation models. Whereas it is concluded that some 2D-models can present the 3D-model, others can’t. The dependent factor is the different cross-section of the electrical machine. The physical experiment shows similar results between simulation in terms of strain at a lower temperature, and the deviation gets larger as the temperature increases. The 3D-model is the model that has the best representation of a real electrical machine as it accounts for all the normal and shear stress components in all directions, but also because it has better boundary conditions compared to the 2D-models. The 2D-model in XY-plane has shown similar results to the 3D-model. One of the main insulation system components, epoxy, is exposed to the highest stresses compared to its yield and ultimate strength, followed by the paper insulation and copper coating. The sensitivity study has concluded that the axial length of the stator does not affect the stress amplitudes. The most critical parameter that affects the thermo-mechanical stresses is the temperature amplitude, the materials CTE and the thickness of the jointed layer. All maximum stress amplitudes of all the components are located at the free end. / Mer effektiva tunga fordon utvecklas med högre räckvidd, uppdaterade elektroniska och mekaniska delar. Bränsleeffektiviteten och föroreningen av koldioxid måste vara lägre för att uppnå nya EU-förordningar. Antalet tunga fordon ökar i takt med att den globala befolkningen ökar, detta leder i sin tur till ökad utsläpp av bland annat koldioxid. Genom att ta de elektriska och mekaniska delarna till nästa steg kan de globala utsläppsproblemen minskas massivt. Elektriska maskiner för framdrivning är nästa steg mot en renare framtid. Studiens huvudmål för att undersöka den elektriska maskinens isoleringssystem. Termomekaniska påfrestningar på grund av termisk cykling påverkar de elektriska maskinerna och dess delkomponenter. Genom att använda en FEM-applikation med förenklade modeller av den elektriska maskinen erhålls och diskuteras resultat. Specifikt om 2D-modeller är tillräckliga för att representera en 3D-modell. Hur tillräckligt de olika 2D-modeller kan representera 3D-modellen jämförs och diskuteras i denna studie. Ett fysiskt experiment utförs för att validera och kalibrera FEA-modellerna. Vilken av de mindre frekventa cykler med högre amplitud eller mer frekventa cyckler med lägre amplitud påverkar isoleringssystemet mest har undersökts. Simuleringarna kan göras med antingen, temperatur kopplad förskjutnings analys eller sekventiellt kopplad analys. Temperatur kopplad kopplad förskjutning är den snabbaste metoden att använda i simuleringsmodellerna. En 3D-modell är det bästa sättet att beskriva ett objekt och har därför implementerats. Ytterligare två, 2Dmodeller är framtagna i FEM-miljö för snabbare beräkning och för att undersöka om 2D-modellerna kan representera den tredimensionella geometrin. Samtliga tre modeller har specifika randvillkor för att förenkla modellerna. Känslighetsstudier görs för att bestämma vilken parameter som påverkar de inducerade termomekaniska spänningarna mest. Ett fysiskt experiment har utförsts för att validera och kalibrera simuleringsmodellerna. Resultatet visar att 3D-modellen representerar ett tre dimensonellt objekt bäst. Simuleringsresultat har visat att epoxy, som är en av huvudkomponenterna i isoleringssystemet, är mest kritisk när det gäller att först nå brott- och sträckgräns, följt av pappersisolering och koppar beläggningen. Detta är ett typiskt resultat av alla tre simuleringsmodeller. Slutsatsen visar att vissa 2D-modeller kan presentera 3D-modellen, andra kan inte. Den beroende faktorn beror på ur vilket tvärsnitt man tittar på den elektriska maskinen. Det fysiska experimentet visar liknande resultat jämfört med simuleringen när det gäller belastning vid en lägre temperatur, och avvikelsen blir större när temperaturen ökar. 3D-modellen, är den modell som har den bästa representationen av en riktig elektrisk maskin eftersom den inkluderar normal- och skjuvspänningskomponenter i alla riktningar. Anledningen är att den har bättre randvillkor jämfört med 2Dmodellerna. 2D-modellen i XY-planet har visat liknande resultat som 3D-modellen. En av huvudkomponenterna i isoleringssystemet, epoxy, utsätts för de högsta spänningarna jämfört med dess sträck- och den brottgräns, följt av pappersisolering och koppar beläggning. Känslighetsstudien har kommit fram till att statorns axiella längd inte påverkar spänningsamplituderna. Den mest kritiska parametern som påverkar de termomekaniska spänningarna är temperatur amplituden, materialens CTE och tjockleken på det skarvade skiktet. Alla maximala spänningsamplituder för samtliga tre komponenter är belägna i den fria änden.

In this work we calculate the binding energies and root-mean-square radii for A−body nuclear bound state systems, where A ≥ 3. To study three−body systems, we employ the three−dimensional differential Faddeev equations with nucleon-nucleon semi-realistic potentials. The equations are solved numerically. For this purpose, the equations are transformed into an eigenvalue equation via the orthogonal collocation procedure using triquintic Hermite splines. The resulting eigenvalue equation is solved using the Restarted Arnoldi Algorithm. Ground state binding energies of the 3H nucleus are determined. For A > 3, the Potential Harmonic Expansion Method is employed. Using this method, the Schr¨odinger equation is transformed into coupled Faddeev-like equations. The Faddeevlike amplitudes are expanded on the potential harmonic basis. To transform the resulting coupled differential equations into an eigenvalue equation, we employ again the orthogonal collocation procedure followed by the Gauss-Jacobi quadrature. The corresponding eigenvalue equation is solved using the Renormalized Numerov Method to obtain ground state binding energies and root-mean-square radii of closed shell nuclei 4He, 8Be, 12C, 16O and 40Ca. / Physics / M. Sc. (Physics)

A K-band integrated super-regenerative amplifier (SRA) in a 130nm SiGe BiCMOS technology is designed and characterized. The circuit is based on a novel stacked transistor differential cross-coupled oscillator topology, with a controllable tail current for quenching the oscillations. The fabricated integrated circuit (IC) occupies an area of 0.63mm2, and operates at the free-running center frequency of 25.3 GHz. Characterization results show circuit operation from a minimum input power level required for a phase coherent output as −110 dBm, and the input power level corresponding to the linear to logarithmic mode transition of −85 dBm, the lowest reported for K-band integrated logarithmic mode SRAs to date to the knowledge of the authors. The measured output power is 7.8dBm into a 100 differential load. The power consumption of the circuit is 110mW with no quench signal applied, and 38mW with 30 % duty cycle quenching. The quench waveform designed for the reported measurement result is also discussed.

We discuss the so-called two-temperature model in linear thermoelasticity and provide a Hilbert space framework for proving well-posedness of the equations under consideration. With the abstract perspective of evolutionary equations, the two-temperature model turns out to be a coupled system of the elastic equations and an abstract ordinary differential equation (ODE). Following this line of reasoning, we propose another model which is entirely an abstract ODE.We also highlight an alternative method for a two-temperature model, which might be of independent interest.

High visual sensitivity is a common but important characteristic of animal eyes. It is especially critical for night vision. In animal eyes, photoreceptors are the first to receive the incoming rays of light and they convert the light signals to electrical signals before passing the information to interneurons in the eye and finally to the brain. To function in dim light conditions, photoreceptors have developed high sensitivities to light. It is reported that both mammalian rod photoreceptors and Drosophilaphotoreceptors can detect single photons. The high sensitivities of photoreceptors largely depend on a high content of rhodopsin, a light-stimulated G protein-coupled receptor (GPCR), in light sensory organelles, outer segments in mammals and rhabdomeres in Drosophila. Two shared characteristics, the tightly packed photoreceptive membrane and the high concentration of rhodopsin in the membrane, work together to enable the photoreceptors to achieve the high content of rhodopsin in photosensory organelles in both mammals and Drosophila. In this thesis, I have used the Drosophilaeye as a model system to study the molecular mechanisms required for the maintenance of these two characteristics. In the second chapter, I present a new molecular mechanism of preventing Gq-mediated rhabdomeral degeneration. A new gene named tadr (for torn and diminished rhabdomeres), when mutated, leads to visual sensitivity reduction and photoreceptor degeneration. Degeneration in the tadr mutant is characterized by shrunken and disrupted rhabdomeres. The TADR protein interacts in vitro with the major light receptor Rh1 rhodopsin, and genetic reduction of the Rh1 level suppresses the tadr-induced degeneration, suggesting the degeneration is Rh1-dependent. Nonetheless, removal of phospholipase C (PLC), a key enzyme in phototransduction, and that of Arr2 fail to inhibit rhabdomeral degeneration in the tadr mutant background. Biochemical analyses reveal that, in the tadr mutant, the Gq protein of Rh1 is defective in dissociation from the membrane during light stimulation. Importantly, reduction of Gq level by introducing a hypomorphic allele of Gαq gene greatly inhibits the tadr degeneration phenotype. These results may suggest that loss of a potential TADR-Rh1 interaction leads to an abnormality in the Gqsignaling, which in turn triggers rhabdomeral degeneration independent of the PLC phototransduction cascade. We propose that TADR-like proteins may also protect photoreceptors from degeneration in mammals including humans. In the third chapter, I present a Drosophila CUB- and LDLa-domain transmembrane protein CULD that counteracts the visual arrestin Arr1-mediated endocytosis to retain rhodopsin in rhabdomeral membrane. CULD is mostly localized in rhabdomeres, but is also detected in scarce rhodopsin endocytic vesicles that contain Arr1. An intracellular region of CULD interacts with Arr1 in vitro. In both culdmutant and knockdown flies, a large amount of rhodopsin is mislocalized in the cell body of photoreceptors through lightdependent, Arr1-mediated endocytosis, leading to reduction of photoreceptor sensitivity. Expressing a wild-type CULD protein in photoreceptors, but not a mutant variant lacking the Arr1-interacting site, rescues both the rhodopsin mislocalization and the low sensitivity phenotypes. Once rhodopsin has been internalized in adult mutant flies, it is reversed only by expression of CULD but not by blocking endocytosis, suggesting that CULD promotes recycling of endocytosed rhodopsin to the rhabdomere. Our results demonstrate an important role of CULD in the maintenance of membrane rhodopsin density and photoreceptor sensitivity. We propose that a common cellular function of CUB- and LDLa-domain proteins, in both mammals and invertebrates, is to concentrate receptors including GPCRs in particular regions of cell membrane. In summary, the work addressed in this thesis has identified new molecular mechavii nisms underlying the maintenance of visual sensitivity in Drosophila, either through preventing Gq-mediated rhabdomeral degeneration or through antagonizing arrestin-mediated rhodopsin endocytosis. This work has advanced our understanding of visual biology and the general regulatory mechanisms of GPCR signaling, and may provide valuable clues to pathologic studies of human retinal degeneration disorders.

The work discusses the development of molecular electronics based on the possibility of the usage of anorganic quantum dots and organic molecules as basis material. Of special interest are the properties of semiconductor quantum dots and their modification due to the coupling of quantum dots from different materials. Eventually these are proper candidates to avoid the fast recombination of excitons which is a problem in many organic photovoltaic materials, by local separation of charge carriers. Another materials class investigated are the so called charge transfer dimers. On the way to usable molecular building blocks switching and rectification behavior are important properties, therefore they were of special interest in the investigation. Especially the usage of charge transfer materials in rectification was already suggested in the 70’s, but could be realized till now only with a quiet limited success. Already around the millennium it was shown that a too strong coupling between the components leads to a resymmetrization of the I-V-characteristics. For all systems the electronic structure was investigated by means of density functional theory. Additional the charge transport in between gold leads was computed based on non equilibrium Greens functions. For the system of coupled quantum dots it is shown how the combination of several gates can be used to adjust the transport properties. This work shows that the rectification effect within weakly coupled charge transfer systems stays also small because also in this case a resymmetrization of the I-V-characteristics takes place.:1 Introduction 2 Molecular Electronics 3 Theoretical background 4 Computational details and software packages 5 Modeling 6 Results and Discussion 6.1 Quantum dots 6.2 Transport through coupled quantum dots 6.3 Charge transfer dimers 6.4 Transport through charge transfer dimers 7 Conclusion 8 Outlook Acknowledgement List of Figures List of Tables Bibliography List of own Publications / Die Arbeit befasst sich mit der Entwicklung der molekularen Elektronik und insbesondere mit der Prüfung der Verwendbarkeit von anorganischen Quantenpunkten und organischen Molekülen für diesen Bereich. Quantenpunkte aus Halbleitermaterialien besitzen eine grosse Bandbreite von Eigenschaften. Es wird untersucht, wie die Eigenschaften durch die Kopplung von Quantenpunkten unterschiedlicher Materialien modifiziert werden können. Eine Idee besteht in der lokalen Trennung von Ladungsträgern um die schnelle Rekombination von Exzitonen zu vermeiden, welche in organischen Solarzellen häufig ein Problem darstellt. Als weitere Materialklasse werden molekulare Ladungstransferdimere untersucht. Auf dem Weg zu nutzbaren Bauelementen sind das Schalt- und Gleichrichtverhalten wichtige Eigenschaften, daher sind sie von besonderem Interesse. Insbesondere die Frage des Ladungstransfers in Bezug auf das Gleichrichten wurde schon in den 1970ern vorgeschlagen, konnte aber bisher immer nur mit begrenztem Erfolg realisiert werden. Schon um die Jahrtausendwende wurde gezeigt, dass Systeme mit einer zu starken Kopplung zu einer Symmetrisierung der Strom-Spannungs-Kennlinie führen. Bei beiden Systemen wird jeweils die elektronische Struktur im Sinne der Dichtefunktionaltheorie berechnet. Zusätzlich wird jeweils der Ladungstransport zwischen Goldkontakten mittels Nichtgleichgewichts-Greenschen Funktionen berechnet. Für die Systeme gekoppelter Quantenpunkte wird gezeigt, wie die Transporteigenschaften mittels Gatespannungen eingestellt werden können. In der vorliegenden Arbeit wird gezeigt, dass es auch im Fall schwach gekoppelter Ladungstransferdimere zu weitgehend symmetrischen Strom-Spannungs-Kennlinien kommt und es auch für diese Systeme nur zu einem schwachen Gleichrichtverhalten kommt.:1 Introduction 2 Molecular Electronics 3 Theoretical background 4 Computational details and software packages 5 Modeling 6 Results and Discussion 6.1 Quantum dots 6.2 Transport through coupled quantum dots 6.3 Charge transfer dimers 6.4 Transport through charge transfer dimers 7 Conclusion 8 Outlook Acknowledgement List of Figures List of Tables Bibliography List of own Publications

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