Government Intervention and Economic Growth

The first essay constitutes a theory which lends truth to the Kuznets hypothesis. The attention is centered on the role of financial markets in defining the process of knowledge accumulation, and ultimately the distribution of income earning capabilities in a population of ex ante heterogeneous individuals. The provision of credit is hindered by one-sided lack of commitment embedded in the area of educational investment. Adaptation in the legislative system to accommodate a punishment scheme conditional on default is the critical requirement for the economy to be carried on a dynamic growth path, albeit one of higher and worsening inequality. Owing to the accumulation of human capital and the associated externality on future generations’ knowledge productivity, the economy ultimately makes its transition to a state of lower income differentials. The second essay is an enquiry on the role of monetary policy in determining the growth dynamics of a small open economy. We postulate that the possibility of intermediated credit does not exist, the intention of the assumption being to uncover the role of inflation as tax on private spending. The analysis brings a valid argument of the superneutrality of money. Inflation when operating as consumption tax has no impact on the growth rate of output. This is established irrespective of the labor supply be held fixed, or incorporated as endogenous decision. When imitating the role of capital taxation, inflationary policy has a negative effect on capital accumulation in a framework of fixed labor supply. However, the validity of the superneutrality result is once again reestablished in an environment accommodating the endogeneity of labor supply. The third essay is a theoretical investigation of the long-run effects of tax and expenditure policies in an open economy framework. The aim is to establish an analytic basis for the factual evidence associated with the non-monotonic response of the current account to fiscal shocks. To this endeavor we sought two sources of time non-separability in the preference structure, habit-forming consumption in consumer durable goods. Optimal private choices induce non-monotonic dynamics on consumption behavior that are exactly consistent with the evidence on the current account

Electron Microscopy and III-Nitride Nanostructured

Ce mémoire de thèse présente une étude structurale de puits et de boîtes quantiques GaN/AIN élaborés par épitaxie par jets moléculaires. La technique d'investigation est la microscopie électronique à transmission, utilisée en modes (i) haute résolution, (ii) imagerie filtrée,(iii) conventionnel et (iv) faisceau convergent. Un chapitre est consacré à l'analyse quantitative des images haute résolution par la méthode de projection et l'analyse de la phase géométrique. Ces méthodes sont analysées et optimisées (par exemple utilisation d'images "off-axis"). Dans les super-réseaux (SL) de puits quantiques GaN/AIN les polarités Ga et N sont analysées. Nous démontrons la supériorité de la qualité structurale des faces Ga: interfaces plus abruptes et uniformes, absence de domaines d'inversion et contraintes moins importantes. Nous analysons aussi l'évolution des nanostructures (puits ou boîtes) durant le processus d'encapsulation et nous prouvons que la croissance de l'AIN induit un amincissement des puits quantiques et une réduction isotrope de la taille des boîtes quantiques. Ce phénomène est attribué à un mécanisme d'échange entre les deux métaux et dépend de la relaxation des couches de GaN. Dans un SL de boîtes quantiques GaN/AIN nous examinons la distribution des contraintes et nous démontrons en combinant des analyses haute résolution, des calculs théoriques et de la diffraction X que l'alignement vertical des boîtes est du à une différence de l'état de contrainte de la couche d'AIN. Enfin, nous prouvons que le dopage au Mg à fortes concentrations d'une couche de GaN face N favorise la conversion de la structure de wurtzite à zinc-blende

Excitonic giant Zeeman effect in GaN:Mn^3+

We describe a direct observation of the excitonic giant Zeeman splitting in (Ga,Mn)N, a wide-gap III-V diluted magnetic semiconductor. Reflectivity and absorption spectra measured at low temperatures display the A and B excitons, with a shift under magnetic field due to s,p-d exchange interactions. Using an excitonic model, we determine the difference of exchange integrals between Mn^3+ and free carriers in GaN, N_0(alpha-beta)=-1.2 +/- 0.2 eV. Assuming a reasonable value of alpha, this implies a positive sign of beta which corresponds to a rarely observed ferromagnetic interaction between the magnetic ions and the holes.Comment: 4 pages, 4 figure

Η συνταγματική προβληματική των θρησκευτικών συμβόλων στους χώρους εκπαίδευσης

Η παρούσα διπλωματική εργασία συνιστά μελέτη της κοινωνικής και συνταγματικής διάστασης του φαινομένου της παρουσίας θρησκευτικών συμβόλων στους χώρους δημόσιας εκπαίδευσης των ευρωπαϊκών κρατών. Το ζήτημα τυγχάνει επίκαιρο, διότι στην Ευρώπη, ήδη από τις αρχές του 21ου αιώνα, η αύξηση των μεταναστευτικών και προσφυγικών ροών και η παράλληλη ενίσχυση των μουσουλμανικών πληθυσμών, έχουν μεταβάλλει την κοινωνικοπολιτισμική σύνθεση της κοινωνίας, έχουν εντείνει τη θρησκευτική ετερότητα και έχουν αναδείξει σημαντικά ζητήματα σεβασμού της διαφορετικότητας. Η σύγχρονη κοινωνική πραγματικότητα, όπως έχει διαμορφωθεί, εντείνει τις υφιστάμενες αμφισβητήσεις αναφορικά με τη θέση της θρησκείας και την έκταση της θρησκευτικής έκφρασης στη δημόσια σφαίρα. Οι χώροι εκπαίδευσης, ως χώροι κρατικής εποπτείας ανήκοντες στην αποκαλούμενη δημόσια σφαίρα, αποτελούν πεδίο σύγκρουσης ατομικών ελευθεριών και κρατικών υποχρεώσεων. Για το λόγο αυτό παρέχουν «γόνιμο» έδαφος για την ανάδειξη κοινωνικών διαφορών και για την αποτύπωση της κοινωνικής ανομοιογένειας. Η χρήση θρησκευτικών σύμβολων στους χώρους εκπαίδευσης από εκπαιδευτικούς, μαθητές και φοιτητές, ως προϊόν αυτοκαθορισμού τους και ως έκφανση της ελεύθερης εκδήλωσης των θρησκευτικών τους πεποιθήσεων, καθώς και η κρατικά επιβαλλόμενη ανάρτηση θρησκευτικών συμβόλων εντός των εκπαιδευτικών αιθουσών έχουν απασχολήσει τα τελευταία χρόνια τόσο τα εθνικά Δικαστήρια και τους εθνικούς νομοθέτες, όσο και το Ευρωπαϊκό Δικαστήριο Δικαιωμάτων του Ανθρώπου. Επομένως, στους ερευνητικούς στόχους της παρούσας εργασίας περιλαμβάνεται η ανάδειξη των ουσιωδώς διαφοροποιημένων προσεγγίσεων που υιοθετούν τα ευρωπαϊκά κράτη απέναντι στο ζήτημα της παρουσίας θρησκευτικών συμβόλων στους χώρους εκπαίδευσης, προσεγγίσεις που αντανακλούν τις ιδιαίτερες σχέσεις κάθε κράτους με την εκκλησία, όπως αυτές διαμορφώθηκαν ως αποτέλεσμα κοινωνικοιστορικών εξελίξεων και διεκδικήσεων, αλλά και η διερεύνηση του ζητήματος υπό το φως της νομολογίας του Δικαστηρίου του Στρασβούργου.The present thesis is a study of the social and constitutional dimension of the presence of religious symbols in public educational institutions in European countries. The issue is topical because in Europe, already since the beginning of the 21st century, the increase in migratory and refugee flows and the parallel strengthening of Muslim populations have changed the socio-cultural composition of society, have intensified religious diversity and have highlighted important issues of respect for diversity. The contemporary social reality, as it has been shaped, has intensified existing disputes about the place of religion and the extent of religious expression in the public sphere. In this context, and given that the symbolic dimension of religion is one of the main characteristics of religious expression, the wearing of the Islamic headscarf in particular, which is not part of the Judeo-Christian European tradition, is often the target of national policies of cultural assimilation. As spaces of state supervision belonging to the so-called public sphere, educational spaces are a field of conflict between individual freedoms and state obligations. For this reason, they provide fertile ground for the emergence of social differences and for the mapping of social heterogeneity. The use of religious symbols in educational institutions by teachers, pupils and students, as a product of their self-determination and as a manifestation of the free expression of their religious beliefs, as well as the state-imposed display of religious symbols in classrooms, have been of concern to national courts and national legislators, as well as to the European Court of Human Rights in recent years. Therefore, the research objectives of this paper include the highlighting of the substantially different approaches adopted by European states towards the issue of the presence of religious symbols in educational institutions, approaches that reflect the particular relations of each state with the church, as they have been shaped as a result of socio-historical developments, as well as the investigation of the issue under the light of the case law of the Strasbourg Court

Growth and optical properties of GaN/AlN quantum wells

We demonstrate the growth of GaN/AlN quantum well structures by plasma-assisted molecular-beam epitaxy by taking advantage of the surfactant effect of Ga. The GaN/AlN quantum wells show photoluminescence emission with photon energies in the range between 4.2 and 2.3 eV for well widths between 0.7 and 2.6 nm, respectively. An internal electric field strength of $9.2\pm 1.0$ MV/cm is deduced from the dependence of the emission energy on the well width.Comment: Submitted to AP

Al4SiC4 w\"urtzite crystal: structural, optoelectronic, elastic and piezoelectric properties

New experimental results supported by theoretical analyses are proposed for aluminum silicon carbide (Al4SiC4). A state of the art implementation of the Density Functional Theory is used to analyze the experimental crystal structure, the Born charges, the elastic and piezoelectric properties. The Born charge tensor is correlated to the local bonding environment for each atom. The electronic band structure is computed including self-consistent many-body corrections. Al4SiC4 material properties are compared to other wide band gap W\"urtzite materials. From a comparison between an ellipsometry study of the optical properties and theoretical results, we conclude that the Al4SiC4 material has indirect and direct band gap energies of about 2.5eV and 3.2 eV respectively.Comment: 10 pages, 4 figure

Local boron doping quantification in homoepitaxial diamond structures

The capability of transmission electronmicroscopy (TEM) using the high angle annular dark fieldmode (HAADF,also labelled Z-contrast) to quantify boron concentration, in the high doping range between 1019cm−3 and 1021cm−3, is demonstrated. Thanks to the large relative variation of atomic number Z between carbon and boron, doping concentration maps and profiles are obtained with a nanometer-scale resolution. A novel numerical simulation procedure allows the boron concentration quantification and demonstrates the high sensitivity and spatial resolution of the technique.4 page

Paramagnetic gold in a highly disordered Au-Ni-O alloy

Magnetic materials are usually classified into a distinct category such as diamagnets, paramagnets or ferromagnets. The enormous progress in materials science allows one nowadays, however, to change the magnetic nature of an element in a material. Gold, in bulk form, is traditionally a diamagnet. But in a ferromagnetic environment, it can adopt an induced ferromagnetic moment. Moreover, the growth of gold under certain conditions may lead to a spontaneous ferromagnetic or paramagnetic response. Here, we report on paramagnetic gold in a highly disordered Au–Ni–O alloy and focus on the unusual magnetic response. Such materials are mainly considered for plasmonic applications. Thin films containing Au, Ni and NiO are fabricated by co-deposition of Ni and Au in a medium vacuum of 2 × 10−2 mbar. As a result, Au is in a fully disordered state forming in some cases isolated nanocrystallites of up to 4 nm in diameter as revealed by high resolution transmission electron microscopy. The disorder and the environment, which is rich in oxygen, lead to remarkable magnetic properties of Au: an induced ferromagnetic and a paramagnetic state. This can be proven by measuring the x-ray magnetic circular dichroism. Our experiments show a way to establish and monitor Au paramagnetism in alloys

Interfacial Properties of Pea Protein Hydrolysate: The Effect of Ionic Strength

The effect of a tryptic hydrolysis as well as the effect of ionic strength (0–0.4 M NaCl) was investigated on the oil/water interfacial properties of soluble pea protein hydrolysate (SPPH) at neutral pH and room temperature (20 \ub1 0.01 \ub0C). SEC-MALS and SDS-Page analysis showed that tryptic hydrolysis created a lower molecular weight polypeptide mixture, whereas FTIR analysis and DSC thermograms demonstrated a more disordered and flexible structure. The bulk properties of SPPH were studied in terms of hydrodynamic diameter and turbidity, where higher particle size (+ ~13 nm) and turbidity were observed at 0.4 M NaCl. Regarding the interfacial properties, the surface activity of SPPH improved by increasing ionic strength, with maximum interfacial pressure (14.28 mN/m) at 0.4 M NaCl. Nevertheless, the addition of NaCl negatively affected the elasticity and strength of the interfacial film, where the sample without salt exhibited the highest dilatational and shear storage modulus in all the frequencies considered