ALICE potential for direct photon measurements in p-p and Pb-Pb collisions

The production of direct photons, not coming from hadron decays, at large transverse momentum pT > 2 GeV/c in proton-proton collisions at the LHC, is an interesting process to test the predictions of perturbative Quantum Chromodynamics at the highest energies ever and to put constraints on the gluon density in the proton. Furthermore, they provide a baseline reference for quark-gluon-plasma studies in Pb-Pb collisions. We will present the experimental capabilities of the ALICE electromagnetic calorimeter EMCal to reconstruct the direct and isolated photon spectra in p-p and Pb-Pb collisions

Modelling the Determinants of Job Creation: Microeconometric Models Accounting for Latent Entrepreneurial Ability

During the last decades, most developed countries have shown a remarcable increase in entrepreneurship rates. Recent research suggests that this increase is, for a considerable part, caused by an increase in the share of solo self-employed. Nowadays, for example, more than half of all Dutch business owners are solo self-employed. This raises the question which factors determine whether an entrepreneur becomes an employer or remains solo self-employed. A recent study by EIM investigates the decision of entrepreneurs whether or not to become an employer and the decision of employers to hire a certain number of employees. The first decision is examined by estimating duration models that model the duration of the time spent as solo entrepreneur before the transition to employer is made. The estimations are performed on a panel of Dutch start-ups in 1998, 1999 and 2000. We find that entrepreneurs who founded a firm to improve their work-life balance are less likely to make the transition to employership. The remaining factors that we found to influence the employer decision do this all in a positive way. These factors include whether or not the entrepreneur has the objective to maximize revenue, experience within the industry in which he operates, his entrepreneurial experience, selfefficacy, risk attitude and the time that is spent in the company. We also find that the likelihood of becoming a job creator is positively related to the business cycle. The second decision is examined by estimating count models that model the number of employees that are hired in the first year of employership. We find that higher levels of educational, entrepreneurial experience and self-efficacy of the entrepreneur lead to a greater firm size. Another factor that increases firm size is innovativeness. The moment in time at which the transition from soloentrepreneur to employer is made, also plays are role. For the first few years we find a negative relationship with firm age, indicating that the faster the switch is made, the more personnel will be employed. Also, for the employee decision we find a positive relation with the business cycle. �

Sensitivity of isolated photon production at TeV hadron colliders to the gluon distribution in the proton

We compare the single inclusive spectra of isolated photons measured at high transverse energy in proton-antiproton collisions at sqrt(s)=1.96 TeV with next-to-leading order perturbative QCD predictions with various parametrizations of the parton distribution functions (PDFs). Within the experimental and theoretical uncertainties, the Tevatron data can be reproduced equally well by the recent CTEQ6.6, MSTW08 and NNPDF1.2 PDF sets. We present also the predictions for isolated gamma spectra in proton-proton collisions at sqrt(s)=14TeV for central (y=0) and forward (y=4) rapidities relevant for LHC experiments. Different proton PDFs result in maximum variations of order 30% in the expected E_T-differential isolated gamma cross sections. The inclusion of the isolated photon data in global PDF fits will place extra independent constraints on the gluon density.Comment: Minor modifications. Matches published version. 13 pages, 10 figure

New Firm Performance: Does the Age of Founders Affect Employment Creation?

The ageing population increasingly becomes a challenge for policy makers. Given the expected changes in the age decomposition of the workforce, it becomes more pressing to understand the nature of the relationship between age and entrepreneurship. More specifically: what are the consequences of an ageing (entrepreneurial) population on entrepreneurial performance?� A recent study by EIM investigates the effect of the age of the entrepreneur at start-up on the size of newly started firms. A distinction is made between the decision of entrepreneurs whether or not to become an employer, and the decision of employers to hire a certain number of employees. To examine to which extent age has a direct and/or indirect effect on these two decision, a sample of 849 new firms has been used that survived the first three years after start-up.� A first conclusion of the empirical analysis is that it is important to make the distinction between the two decisions: the decision of entrepreneurs whether or not to become an employer depends on other factors than the decision of employers regarding the number of employees. A second conclusion is that age has a negative relationship with the outcome of both decisions, but that these relationships are completely mediated by the mediating variables included in the study. Entrepreneurs who start at older age are less likely to work fulltime in their new venture, are less willing to take risks and have a lower perception of their entrepreneurial skills. Each of these factors has, in turn, a positive impact on the probability of employing personnel. For the number of employees a negative indirect effect of age exists, through the effect of age on the perception of entrepreneurial skills. �

Studies of isolated photon production in simulated proton-proton collisions with ALICE-EMCal

The production of prompt photons at high transverse momentum in proton-proton collisions (p-p) is a useful tool to study perturbative Quantum-Chromo-Dynamics (pQCD). In particular, they yield valuable information about parton distribution functions in the proton. The experimental measurement of prompt photons is a difficult task due to the large background of decay photons from neutral mesons, mainly pi0. We present a full simulation and reconstruction study of prompt photons identification in p-p at sqrt(s) = 14 TeV in the ALICE electromagnetic calorimeter EMCal, giving details on the methods developed to separate them from decay photons with the help of shower-shape and isolation cuts. We present Monte Carlo predictions for signal and background. The method used to extract the final isolated corrected cross-section is presented and the calculation of various experimental corrections is outlined.Comment: 4 pages, 6 figures. Proceedings Hot Quarks 2010 La-Londe-les-Maures (France), JPG submitte

What determines the volume of informal venture finance investment and does it vary by gender?

We estimate a two-equation model to jointly determine the number of informal investors and the amount of money that they invest over the last 3 years. Our model uses data on 126,189 individuals in 21 highly developed countries in the period 2002-2006. We delve deeper into the hypothesis of Burke et al (2010) that ‘the demand for informal venture finance tends to generate its own supply’. To our knowledge, we undertake the first research to move analysis of the supply of informal venture finance investment beyond estimating the propensity for a person to become an informal investor and onto the core concern which is the total volume of venture finance. We find that a one per cent increase in entrepreneurial activity increases the number of informal investors by 1.702 per cent. However, the average invested amount declines by 0.827 per cent leading to a net positive total increase by 0.861 per cent. This result indicates that, to a considerable extent, demand for informal investment creates its own supply. This effect is stronger for males than females. We also find that the level of venture capital investment has a net positive effect on the level of informal investment and that this effect is stronger for females than males.

X-ray diffraction study of cadmium hydroxyapatite

Solid solutions of cadmium and calcium hydroxyapatite [Ca10−x Cdx (PO4)6 (OH)2 (0 ≤ x ≤ 10)] were synthesized by a wet process in a basic medium. The lattice dimensions of these compounds vary linearly with the atom percent cadmium. The distribution of the calcium and cadmium ions between two non- equivalent crystallographic sites, (1) and (2), were determined by the Rietveld method. The site-occupancy factors of atoms indicate a slight preference of cadmium for site (2) in the apatite structure

France

Racial and ethnic inequalities remain an underdeveloped area of research in France. This situation can mainly be attributed to the fact that researchers have been strongly influenced, on the one hand, by a political model of integration (presented in more detail in Section 12.3.3) that has led France ‘to ignore itself as a country of immigration’ (Noiriel, 1988) and encouraged a colorblind approach to social reality (Lorcerie, 1994a) and, on the other hand, by Marxist political and scientific perspectives giving central importance to class in the study of society. However, since the 1980s, due to important changes in the immigrant population and in policy towards immigrants, as well as to the arrival of a new generation of researchers and the growing internationalization of French research, the number of studies in this domain has increased and diversified. There are however very few reviews of the existing scientific literature (Lorcerie, 1995, 2003; Payet, 2003; Payet and van Zanten, 1996; van Zanten, 1997b) and only one in English (van Zanten, 1997a). Therefore, the following critical survey, based on a systematic sampling of the literature and covering 30 years of research, including very recent studies, should prove useful to various, and especially anglophone, audiences. [Chapter's first paragraph

Origine migratoire et inégalités scolaires : étude longitudinale des résultats scolaires des descendants d’immigrés en France et en Angleterre

Ce texte propose une analyse quantitative de l’évolution des résultats scolaires des descendants d’immigrés de l’école primaire à la fin de l’enseignement secondaire en France et en Angleterre, grâce à l’exploitation de trois panels d’élèves de grande ampleur : les panels 1995 et 1997 du ministère de l’Éducation nationale en France, la Longitudinal Study of Young People in England (LSYPE) en Angleterre. Les résultats obtenus montrent que, par-delà les effets de leur origine sociale, les descendants d’immigrés de Turquie ont des résultats scolaires systématiquement plus bas que les autres en France, alors que les enfants d’immigrés d’Asie du Sud-Est et de Chine se situent, des deux côtés de la Manche, au sommet de la stratification scolaire. Le fort rattrapage scolaire des descendants d’immigrés par rapport aux enfants de natifs dans le secondaire en Angleterre contraste avec le décrochage relatif de la plupart des enfants d’immigrés dans les collèges français. Au total, il semble que, par rapport aux enfants de natifs, les descendants d’immigrés s’en sortent mieux en Angleterre qu’en France. En plus de leur position sociale dans le pays d’immigration, les propriétés sociales pré-migratoires des parents immigrés, en particulier leur position éducative relative dans leur pays d’origine, permettent de rendre compte des positions scolaires de leurs enfants au sein des systèmes scolaires français et anglais.This paper provides a quantitative analysis of the academic achievement of descendants of immigrants from primary school to the end of secondary education in France and England. Three large-scale panel surveys of students are used: the 1995-2006 and 1997-2007 panel studies by the French Ministry of Education and the 2004-2010 Longitudinal Study of Young People in England (LSYPE). The results show that, over and above the effects of their socioeconomic background, the children of Turkish immigrants have consistently lower academic achievement than other groups in France, while descendants of immigrants from Southeast Asia and China are at the top of the academic stratification in both France and England. In England, descendants of immigrants catch up with children of natives during secondary education, while they tend to fall behind in French secondary schools. Overall, compared to children of natives, descendants of immigrants fare better academically in England than in France. In addition to their socioeconomic background in the destination country, immigrant parents’ pre-migration characteristics, especially their educational position relative to their country of origin, help explain the academic achievement of their children within the French and English school systems

Vers des nano-électrodes sur semi-conducteurs grand gap. Graphène/SiC, silicène/graphène/SiC et Au/AlN/SiC. Epitaxie et caractérisation NC-AFM/KPFM

L'objectif ultime de ce travail est l'élaboration puis la caractérisation de nouveaux matériaux utilisés pour réaliser des nanopads destinés à l'électronique moléculaire. Ces nanopads doivent répondre à des critères stricts pour stabiliser, sans déformation et avec une précision atomique, la molécule dans la jonction nanopad-surface-nanopad. En combinant la microscopie à force atomique sans contact (nc-AFM) et la microscopie à sonde Kelvin (KPFM) dans un environnement ultravide (UHV), nous avons mesuré la hauteur et le travail de sortie d’une monocouche de graphène sur la face Si du 6H-SiC (0001). Ces mesures nous ont permis d’identifier trois structures de graphène : La ZLG (couche tampon), la QFMLG et la BLG. Contrairement aux autres méthodes de spectroscopie, le nc-AFM couplé à une sonde KPFM nous a permis ensuite d'identifier directement des nano-îlots de graphène aux premiers stades de nucléation, élaborée par dépôt chimique en phase vapeur (CVD). Le système graphène/SiC/graphène est prometteur pour la réalisation des jonctions en géométrie planaire. Dans la deuxième partie de cette thèse nous avons exploré la croissance de nanopads en silicène dans une chambre d’épitaxie par jets moléculaires (EJM). Nous avons démontré que la croissance du silicium sur graphène n'est pas bidimensionnelle et conduit à la formation des amas 3D ayant des branches fractales. Enfin, nous avons déposé par EJM des nano-îlots d'or sur un film mince d'AlN. Ce système est très prometteur et répond à un grand nombre de critères pour réaliser un dispositif à une seule molécule. Les nano-îlots d'or sont d'épaisseur monoatomique et peuvent être chargés électriquement avec la pointe AFM de manière contrôlée. Il reste alors, à titre de perspective, à synthétiser des nano-rubans moléculaires de graphène sur cette surface pour préparer la mesure de leur conductance à plat.The ultimate goal of this work is the elaboration and characterization of new materials used to realize nanopads for molecular electronics. These nanopads must meet strict criteria to stabilize, without deformation and with atomic precision, the molecule on the nanopad-surface-nanopad junction. By combining non-contact atomic force microscopy (nc-AFM) and Kelvin probe microscopy (KPFM) in ultra high vacuum environment (UHV), we directly measure the height and work function of graphene monolayer on the Si-face of 6H-SiC(0001) with a precision that allows us to differentiate three different graphene structures : Zero layer graphene (ZLG), Quasi free-standing monolayer graphene (QFMLG) and Bilayer graphene (BLG). Unlike any other available technique, the local nc-AFM/KPFM dual probe makes it possible to directly identify the nature of nanometer-sized graphene islands that constitute the early nuclei of graphene monolayer grown on 6H-SiC(0001) by chemical vapour deposition. In the second part of this thesis we explored the growth of silicon nanopads by molecular beam epitaxy. We have shown that the growth of silicon on graphene is not two-dimensional and leads to the formation of 3D clusters with fractal branches. Finally, we epitaxially deposited gold nanoislands on an AlN(0001) thin film. This system is very promising and meets many of the criteria required for single molecule devices. The gold islands are mono-atomic and can be electrically charged with the AFM tip. It remains then to synthesize graphene nano-ribbons (GNRs) on this surface to prepare the conductance measurement