Magister Public Health - MPH / Objectives: To document the distribution of medical doctors between the National Health System (NHS), NGOs and the Private Sector over the period 2000-2010; (2) To explore the perceptions of medical doctors (MDs) and human resources managers (HRMs) regarding factors that influence MD internal brain drain in Maputo city, Mozambique, more specifically, the movement of doctors from the Mozambican NHS to NGOs and the private sector within Mozambique.

Depuis les années 60, la génération d’acide fort de Brönsted par un processus photoinduit à un photon est utilisée dans des nombreux domaines de recherche de plus en plus nombreux. Cependant, de tels acides peuvent-être facilement obtenus par voie biphotonique ce qui présente de nombreux avantages comme par exemple : une meilleure réactivité via une excitation direct du photoacide, l’utilisation possible d’une atmosphère non contrôlée, l’utilisation de microlasers à impulsions sub-nanosecondes peu couteux, mais aussi l’augmentation de la résolution spatiale des micro-objets 3D fabriqués. La génération d’acide se fait généralement par transfert d’électron entre un sensibilisateur et un générateur de photoacide (PAG). Une approche prometteuse consiste à associer, sur une même molécule, un PAG et un chromophore actif à deux photons. Il a donc semblé intéressant de développer de nouveaux PAG capables, par excitation biphotonique, d’amorcer directement la photopolymérisation. Nous avons choisi de préparer des systèmes capto-datifs stilbéniques, de nature neutre ou ionique. Aussi, une série de PAG neutres substitués par des groupements diphénylamino- donneur et iminosulfonates -cyanés accepteurs a été synthétisée. Nous avons également commencé, mais non achevé, la synthèse de PAG neutres portant des groupements iminosulfonates -trifluorométhylés. Puis, nous avons cherché à synthétiser des PAG ioniques substitués soit par un groupement éthoxy soit par un groupement diphénylamino soit par un groupement julolidine. Néanmoins, la dernière étape de la synthèse est pour l’instant un verrou synthétique. / Since the 60’s, the generation of strong Brönsted acids by a one-proton photoinduced process has been used in more and more research areas. Recently, it has been shown, that such acids are easily obtained by a two-photon process. This offers many advantages such as: i) a better reactivity owing to a direct excitation of the photoacid, ii) the possible use of a non-controlled atmosphere, iii) the use of inexpensive microlasers with sub-nanosecond impulsions, iv) the increase of spatial resolution in 3D microfabrication. The acid generation generally proceeds through a photo-induced electro transfer from an excited sensitizer to the photoacid generator (PAG). A promising approach should be the introduction on a single molecule of both a PAG and a two-photon active chromophore moiety. In this context, we have developed new PAGs able to initiate photopolymerisation through a two-photon activation process. The syntheses were focused on stilbenic push-pull systems having either a neutral or an ionic nature. A series of neutral PAGs bearing a diphenylamino donor group and an α-cyano iminosulfonate acceptor moiety has been synthesized. The preparation of neutral PAGs bearing iminosulfonate α-trifluoromethylated groups were not yet completed. The syntheses of ionic PAGs substituted by an ethoxy group, a diphenylamino group or a julolidine one, could not be completed either.

This research aims to gain a detailed understanding of the push and pull factors that lead many Syrians in Turkey to migrate to Europe. Syrians are pushed to migrate for various reasons, including socio-economic difficulties in Turkey. It explores the Syrians’ experiences in Turkey and the elements that have deterred them from gaining the fundamental rights of accommodation, access to the labor market, and refugee status. The pull factors refer to the gains that the Syrians might achieve when migrating to Europe. These gains are socio-economic gains that assure a better future for them in Europe in comparison to their presence in Turkey. In this case, this research also explores how the Syrians plan to migrate to Europe by employing the influence of their social networks to conduct their secondary migration. This qualitative study uses seven semi-structured interviews and analyzes the experiences of the interviewees in order to reach concrete conclusions. The results of this study, according to the interviewees’ experiences, show that restrictive Turkish policies and procedures have pushed many Syrians to migrate. At the same time, the Syrians are attracted to migrating to Europe for better protection for them and their children. The findings also demonstrate that social ties influenced Syrians in their decision to migrate to Europe and avoid being deported to Syria.

Laboratory push – pull switching power supply with symetrical output 2x0-30 V/5 A, primarily through adjustable controls (buttons, rotary encoder position) and then displayed on the alphanumeric LCD display. Management and communication device between the user and the power supply of the microcontroller ATmega32 - 16PU.

The thesis is focused on design the switching power supply according to Push-pull topology rules. The work describes basic theoretic principles of Push-pull topology with design of circuit and circuit elements.

Im Rahmen der EU-Osterweiterung werden spätestens 2011 sämtliche Migrationsrestriktionen für die Beitrittsländer Polen, Ungarn, Tschechische Republik, Estland und Slowenien gegenüber den Alt-EU-Ländern dauerhaft abgeschafft. Veränderte Migrationsprozesse, die in der öffentlichen Diskussion häufig mit überzogenen Erwartungen in Bezug auf das Ausmaß möglicher Zuwanderung verbunden werden, gelten in diesem Kontext als wahrscheinlich. Für eine sachliche Diskussion und Bewertung potenzieller Auswirkungen, welche mit einem Ansteigen bzw. Sinken von Emigration und Imigration für Aufnahme- aber auch für die Herkunftsländer- einhergehen können, ist eine realistische Schätzung der Größenordnung des möglichen Migrationspotenzials nicht nur hilfreich, sondern mit Blick auf denkbare künftige EU-Erweiterungen unbedingt erforderlich. Die Entwicklung eines eigenständigen Modells zur Vorausschätzung der Zuwanderung aus den genannten EU-Beitrittsländern nach Deutschland steht im Mittelpunkt dieser Dissertation. Methodisch werden zunächst aus den thematisch relevanten empirischen Informationen und theoretischen Grundlagen Push- und Pull-Faktoren für Migrationsprozesse abgeleitet und Schritt für Schritt in einem Werkzeug integriert, welches dann in seiner Anwendung jeweils neun Migrationszenarien für jedes einzelne Beitrittsland liefert. Diese neun Szenarien bilden einen Korridor, in den mit hoher Wahrscheinlichkeit die tatsächliche Entwicklung fällt.

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I det hållbara planeringsidealet anses cykeln vara en viktig del av en fungerande trafiklösning, trots detta tenderar många städer ha problem att uppnå deras egna mål för ökad cykeltrafik. Studien analyserar Malmös och Köpenhamns cykelplanering och cykelvägsstruktur utifrån aktuell cykeltrafikforskning, i syfte att undersöka vilka strategier och förutsättningar som städerna har gemensamt, och vad som skiljer dem åt. Målet för studien är att få svar på hur, och i vilken mån Malmös cykeltrafikandel kan öka utifrån Köpenhamns exempel, och att få en vidare förståelse för de utmaningar som den framtida cykelplaneringen står inför. Studiens metod tar ansats ur fältstudier av fyra cykelfrämjande städer i Europa. Sammanställningen av fältstudierna resulterar i att tre cykelstrategier identifieras som gemensamma för de fyra cykelfrämjande städerna. Därefter analyseras Köpenhamns och Malmös cykelprogram utifrån de tidigare nämnda cykelstrategierna. Analysen fastslår att Köpenhamn borde ses som en framstående cykelstad och möjliggör för en jämförande analys mellan Köpenhamns och Malmös cykelsatsningar. Den jämförande analysen mellan Köpenhamns och Malmös cykelsatsningar avslutas med en redovisning och tolkning av resultaten från analysen.För att kunna förstå cykelprogrammens spatiala relation till städerna de är tänkta att implementeras i används en space syntax-analys. Genom att undersöka satsningarnas rumsliga kontext i förhållande till det befintliga cykelvägsystemet kan en djupare förståelse för cykelsatsningarnas omfattning och orsak uppnås.Studiens resultat identifierar tre strategier som är direkt kopplade till andelen cykeltrafik i städer. Den fastställer även att trots cykelsatsningarnas övergripande likheter, skiljer implementeringen och omfattningen av dessa satsningar sig åt mellan Köpenhamn och Malmö. Infrastrukturens stora påverkan på cykelutvecklingen i stort framgår även det i studiens resultat. Studien visar även på hur de båda städernas cykelprogram förhåller sig till cykelns socialt utjämnande egenskaper. Resultatet visar att det finns indikationer från båda städernas framtida cykelplanering på att dessa utjämnande egenskaper har fått en lägre prioritering allt efter cykeltrafiken anpassas till starkare samhällsgrupper. / In the sustainable planning paradigm, the bicycle is seen as playing an important role of combining effective, environmentally friendly, and space conserving transport to the compact city. Despite its overall positive effect on city life, many cities seem to struggle to achieve the goal of increased bicycle traffic. This study studies the similar strategies and efforts used by bicycle friendly European cities through current research literature, in order to analyze Malmö’s and Copenhagen’s efforts to increase their bicycle traffic. The goal of the study is to examine Malmö’s potential for increased bicycle traffic through Copenhagen’s bicycle planning strategies, and to get a deeper understanding of the challenge’s that may face the future field of bicycle planning. The study’s method starts in field studies of four bicycle friendly European cities. The compilation of the field studies identifies three bicycle planning strategies as mutual for all four cities. The mutual bicycle strategies are then used as a tool and benchmark for the analysis of Copenhagen´s and Malmoe´s municipal bicycle program. To understand the spatial relation between the cities bicycle strategies and the street network that they are supposed to be implemented in, a space syntax-analysis is performed. The results from the comparative analysis of the cities bicycle programs and the space syntax-analysis is then summarized and discussed. The result of the study identifies three crucial criteria’s that according to the study has a high possibility of affecting a city’s bicycle share. It also points to the importance of a well-developed bicycle infrastructure to achieve a higher level of competitiveness for the bicycle as a mode of transport. The study also highlights the socially balancing properties of the bicycle as a mode of transport, and the concern of losing these properties due to bicycle planning strategies that is starting to be adapted in order to attract people from more affluent social groups.

Donor-acceptor systems exhibit distinctive attributes rendering them highly promising for the emulation of natural photosynthesis and the efficient capture of solar energy. This dissertation is primarily devoted to the investigation of these unique features within diverse donor-acceptor system typologies, encompassing categories such as closely covalently linked, push-pull, supramolecular, and multi-modular donor- acceptor conjugates. The research encompasses an examination of photosynthetic analogs involving compounds such as chelated azadipyromethene (AzaBODIPY), N,N-dimethylaminophenyl (NND), phenothiazine (PTZ), triphenylamine (TPA), phenothiazine sulfone (PTZSO2), tetracyanobutadiene (TCBD), and expanded tetracyanobutadiene (exTCBD). The strategic configuration of the donor (D), acceptor (A), and spacer elements within these constructs serves to promote intramolecular charge transfer (ICT), which are crucial for efficient charge and electron transfer. The employment of cutting-edge analytical techniques, such as ultrafast transient absorption spectroscopy, is integral to the study. Furthermore, a comprehensive suite of analytical methodologies including steady-state UV-visible absorption spectroscopy, fluorescence and phosphorescence spectroscopies, electrochemical techniques (including cyclic voltammetry and differential pulse voltammetry), spectroelectrochemistry, and density functional theory calculation (DFT), collectively contribute to the comprehensive characterization of push-pull donor-acceptor systems, with a particular emphasis on their potential as highly effective solar energy harvesting application.

High-frequency and large amplitude current is a driving requirement for applications such as induction heating, wireless power transfer, power amplifier for magnetic resonant imaging, electronic ballasts, and ozone generators. Voltage-fed resonant inverters are normally employed, however, current-fed (CF) resonant inverters are a competitive alternative when the quality factor of the load is significantly high. The input current of a CF resonant inverter is considerably smaller than the output current, which benefits efficiency. A simple, parallel resonant tank is sufficient to create a high-power sinusoidal signal at the output. Additionally, input current is limited at the no-load condition, providing safe operation of the system. Drawbacks of the CF resonant inverter are associated with the implementation of the equivalent current source. A large input inductor is required to create an equivalent dc current source, to reduce power density and the bandwidth of the system. For safety, a switching stage is implemented using bidirectional voltage-blocking switches, which consist of a series connection of a diode and a transistor. The series diode experiences significant conduction loss because of large on-state voltage. The control of the output current amplitude for constant-frequency inverters requires a pre-regulation stage, typically implemented as a cascaded hard-switched dc/dc buck converter. The pre-regulation also reduces the efficiency. In this dissertation, a variety of CF resonant inverters with two input inductors and two grounded switches are investigated for an inductive-load driver with loaded quality factor larger than ten, constant and high-frequency (~500 kHz) operation, high reactive output power (~14 kVA), high bandwidth (~100 kHz), and high efficiency (over 95 %). The implementation of such system required to question the fundamental operation of the CF resonant inverter. The input inductance is reduced by around an order of magnitude, ensuring sufficient bandwidth, and allowing rich harmonic content in the input current. Of particular importance are fundamental and second harmonic components since they influence synchronization of the zero-crossing of the output voltage and the turn-on of the switches. The synchronization occurs at a particular frequency, termed synchronous frequency, and it allows for zero switching loss in the switches, which greatly boosts efficiency. The synchronous conditions were not know prior this work, and the dependence among circuit parameters, input current harmonics, and synchronous frequency are derived for the first time. The series diode of the bidirectional switch can reduce the efficiency of the system to below 90 %, and has to be removed from the system. The detrimental current-spikes can occur if the inverter is not operated in synchronous condition, such as in transients, or during parametric variations of the load coil. The resistance of the load coil has a wide variance, five times or more, while the inductance changes as well by a few percent. To accommodate for non-synchronous conditions, a low-loss current snubber is proposed as a safety measure to replace lossy diodes. The center-piece of the dissertation is the proposal of a two-phase zero-voltage switching buck pre-regulator, as it enables fixed frequency and synchronous operation of the inverter under wide parametric variations of the load. The synchronous operation is controlled by phase-shifting the switching functions of the pre-regulator and inverter. The pre-regulator reduces the dc current in the input inductors, which is a main contributor to current stress and conduction losses in the inverter switches. Total loss of the inverter switches is minimized since no switching loss is present and minimal conduction losses are allowed. The dc current in the input inductors, once seen as a means to transfer power to load, is now contradictory perceived as parasitic, and the power is transferred to the load using a fundamental frequency harmonic! The input current to the resonant tank, previously designed to be a square-wave, now resembles a sine-wave with very rich harmonic content. Additionally, the efficiency of the pre-regulator at heavy-load condition is improved by ensuring ZVS for with an additional inductive tank. The dissertation includes five chapters. The first chapter is an introduction to current-fed resonant inverters, applications, and state-of-the-art means to ensure constant frequency operation under load's parametric variations. The second chapter is dedicated to the optimization of the CF resonant inverter topology with a dc input voltage, two input inductors, and two MOSFETs. The topology is termed as a boost amplifier. If the amplifier operates away from the synchronous frequency, detrimental current spikes will flow though the switches since the series diodes are eliminated. Current spikes reduce the efficiency up to few percent and can create false functioning of the system. Operation at the synchronous frequency is achieved with large, bulky, input inductors, typically around 1-2 mH or higher, when the synchronous frequency follows the resonant frequency of the tank at 500 kHz. The input inductance cannot be reduced arbitrarily to meet the system bandwidth requirement, since the synchronous frequency is increased based on the inductance value. The relationship between the two (input inductance and the synchronous frequency) was unknown prior this work. The synchronous frequency is determined to be a complicated mathematical function of harmonic currents through the input inductors, and it is found using the harmonic decomposition method. As a safety feature, a current snubber is implemented in series with the resonant tank. Snubber utilizes a series inductance of cable connection between the tank and the switching stage, and it is more efficient than the previously employed series diodes. Topology optimization and detailed design procedure are provided with respect to efficiency and system dynamics. The mathematics is verified by a prototype rated at 14 kVA and 1.25 kW. The input inductance is reduced by around an order of magnitude, with the synchronous frequency increase of 2 %. The efficiency of the power amplifier reached 98.5 % and might be improved further with additional optimization. Silicon carbide MOSFETs are employed for their capability to operate efficiently at high frequency, and high temperature. The third chapter is dedicated to the development of the boost amplifier's large signal model using the Generalized State-space Averaging (GSSA) method. The model accurately predicts amplifier's transient and steady-state operation for any type of input voltage source (dc, dc with sinusoidal ripple, pulse-width modulated), and for either synchronous or non-synchronous operating frequency. It overcomes the limitation of the low-frequency model, which works well only for dc voltage-source input and at synchronous frequency. As the measure of accuracy, the zero-crossing of the resonant voltage is predicted with an error less than 2° over a period of synchronous operation, and for a range of interest for input inductance (25 μH – 1000 μH) and loaded-quality factor (10 – 50). The model is validated both in simulation and hardware for start-up transient and steady-state operation. It is then used in the synthesis of modulated output waveforms, including Hann-function and trapezoidal-function envelopes of the output voltage/current. In the fourth chapter, the GSSA model is employed in development of the PWM compensation method that ensures synchronous operation at constant frequency for the wide variation of the load. The boost amplifier is extended with a cascaded pre-regulator whose main purpose is to control the output resonant voltage. The pre-regulator is implemented as two switching half-bridges with same duty-cycle and phase-shift of 180°. The behavior of the cascaded structure is the same as of the buck converter, so the half-bridges are named buck pre-regulators. ZVS operation is ensured by putting an inductive tank between the half-bridges. Each output of half-bridges is connected to each of input inductors of the boost to provide the PWM excitation. Using the GSSA model, the synchronous condition and control laws are derived for the amplifier. Properties of the current harmonics in the input inductors are well examined. It is discovered that the dc harmonic, once used to transfer power, is unwanted (parasitic) since it increases conduction loss in switches of the boost. A better idea is to use the fundamental harmonic for power transfer, since it does not create loss in the switches. Complete elimination of the dc current is not feasible for constant frequency operation of the amplifier since the dc current depends on the load coil's resistance. However, significant mitigation of around 55 % is easily achievable. The proposed method improves significantly the efficiency of both the buck pre-regulator and the boost. Synchronous operation is demonstrated in hardware for fixed switching frequency of 480 kHz, power level up to 750 W, input voltage change from 300 V to 600 V, load coil's resistance change of three times, and load coil's inductance change of 3.5 %. Measured efficiency is around 95 %, with a great room for improvements. Chapter five summarizes key contributions and concludes the dissertation. / Ph. D.