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Search Results: 1 - 10 of 15822 matches for " Michèle Fichet "
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Selective Reflection Spectroscopy on the UV Third Resonance Line of Cs : Simultaneous Probing of a van der Waals Atom-Surface Interaction Sensitive to Far IR Couplings and of Interatomic Collisions
Pedro Chaves De Souza Segundo,Ismahène Hamdi,Michèle Fichet,Daniel Bloch,Martial Ducloy
Physics , 2007, DOI: 10.1134/S1054660X07070134
Abstract: We report on the analysis of FM selective reflection experiments on the 6S1/2->8P3/2 transition of Cs at 388 nm, and on the measurement of the surface van der Waals interaction exerted by a sapphire interface on Cs(8P3/2). Various improvements in the systematic fitting of the experiments have permitted to supersede the major difficulty of a severe overlap of the hyperfine components, originating on the one hand in a relatively small natural structure, and on the other hand on a large pressure broadening imposed by the high atomic density needed for the observation of selective reflection on a weak transition. The strength of the van der Waals surface interaction is evaluated to be 73$\pm$10 kHz.$\mu$m3. An evaluation of the pressure shift of the transition is also provided as a by-product of the measurement. We finally discuss the significance of an apparent disagreement between the experimental measurement of the surface interaction, and the theoretical value calculated for an electromagnetic vacuum at a null temperature. The possible influence of the thermal excitation of the surface is evoked, because, the dominant contributions to the vW interaction for Cs(8P3/2) lie in the far infrared range.
Selective Reflection Spectroscopy at the Interface between a Calcium Fluoride Window and Cs Vapour
Athanasios Laliotis,Isabelle Maurin,Michèle Fichet,Daniel Bloch,Martial Ducloy,Nikolay Balasanyan,Asphet Sarkisyan,David Sarkisyan
Physics , 2007, DOI: 10.1007/s00340-007-2927-9
Abstract: A special vapour cell has been built, that allows the measurement of the atom-surface van der Waals interaction exerted by a CaF2 window at the interface with Cs vapour. Mechanical and thermal fragility of fluoride windows make common designs of vapour cells unpractical, so that we have developed an all-sapphire sealed cell with an internal CaF2 window. Although impurities were accidentally introduced when filling-up the prototype cell, leading to a line-broadening and shift, the selective reflection spectrum on the Cs D1 line (894 nm) makes apparent the weak van der Waals surface interaction. The uncertainties introduced by the effects of these impurities in the van der Waals measurement are nearly eliminated when comparing the selective reflection signal at the CaF2 interface of interest, and at a sapphire window of the same cell. The ratio of the interaction respectively exerted by a sapphire interface and a CaF2 interface is found to be 0.55 $\pm$ 0.25, in good agreement with the theoretical evaluation of ~0.67.
Testing the distance-dependence of the van der Waals interaction between an atom and a surface through spectroscopy in a vapor nanocell
Athanasdios Laliotis,Isabelle Maurin,Petko Todorov,Ismahène Hamdi,Gabriel Dutier,Alexander Yarovitski,Solomon Saltiel,Marie-Pascale Gorza,Michèle Fichet,Martial Ducloy,Daniel Bloch
Physics , 2007, DOI: 10.1117/12.726798
Abstract: This paper presents our current measurements in a vapor nanocell aiming at a test of the distance-dependence of the atom-surface interaction, when simple asymptotic descriptions may turn to be not valid. A state-of-the-art of atom-surface interaction measurements is provided as an introduction, along with the comparison with the theory of the van der Waals (or Casimir-Polder) interaction; it is followed by a presentation of the most salient features of nanocell spectroscopy
Exploring the van der Waals Atom-Surface attraction in the nanometric range
Michèle Fichet,Gabriel Dutier,Alexander Yarovitski,Petko Todorov,Ismahène Hamdi,Isabelle Maurin,Solomon Saltiel,David Sarkisyan,Marie-Pascale Gorza,Daniel Bloch,Martial Ducloy
Physics , 2006, DOI: 10.1209/0295-5075/77/54001
Abstract: The van der Waals atom-surface attraction, scaling as C3 z-3 for z the atom-surface distance, is expected to be valid in the distance range 1-1000 nm, covering 8-10 orders of magnitudes in the interaction energy. A Cs vapour nanocell allows us to analyze the spectroscopic modifications induced by the atom-surface attraction on the 6P3/2->6D5/2 transition. The measured C3 value is found to be independent of the thickness in the explored range 40-130 nm, and is in agreement with an elementary theoretical prediction. We also discuss the specific interest of exploring short distances and large interaction energy.
Multinational Corporations in Transnational Networks: Theoretical and Regulatory Challenges in Historical Perspective  [PDF]
Michèle Rioux
Open Journal of Political Science (OJPS) , 2014, DOI: 10.4236/ojps.2014.43012
Multinational corporations (MNCs) have become the most powerful drivers of integration and structural changes in today’s global economy. MNCs have not completely subordinated States and markets in shaping the global economy, but they have transformed the world and given rise to a new set of economic, political, social, cultural and legal problems. Yet, quite ironically, MNCs are now facing a recombination that tends to subordinate them to transnational networks of corporate economic power. The thorny issue of regulating the global economy is, in this context, even more complex as regulatory systems of global governance must be built to fit those transnational networks superseding States and firms. This article presents an overview of the most important theories in international political economy on MNCs in order to situate the new theoretical challenges pertaining to the understanding of contemporary structural changes in the world economy and their incidences on global governance. The first section presents three configurations of globalization and concludes on the theoretical challenges of explaining and understanding the emergence and development of transnational economic networks. A second section discusses some current issues of regulation. The overall statement of this article is that globalization has, during the last decades, transformed international political economy in ways that now require new theoretical paradigms and new modes of global regulation that are adapted to a truly global economy made of networks rather than nations or firms.
The Perils of Outcomes-Based Education in Fostering South African Educational Transformation  [PDF]
Michèle J. Schmidt
Open Journal of Political Science (OJPS) , 2017, DOI: 10.4236/ojps.2017.73030
Abstract: This chapter explored a South African education policy. Specifically the author?examined outcomes-based learning and the implications of this borrowed curriculum in South African schools.?The author?focused on curriculum as a?platform for discussion of the unique approach?that?the South African government employed to modify their adoption of democracy and transformation. Unfortunately, many scholars reluctantly concede that South Africa’s?ambitious policy initiatives failed to provide social justice in schools.?Education?is often the driving force in society: socially, economically, and politically. In particular, education can either liberate social ideologies or become a tool to reinforce stratification. With a political ideology of democracy emerging in South Africa, one would think that democratic educational structures would act to diminish race, class and gender inequalities; however, this has not been a pervasive result.
Laser spectroscopy with nanometric gas cells : distance dependence of atom-surface interaction and collisions under confinement
Ismahène Hamdi,Petko Todorov,Alexander Yarovitski,Gabriel Dutier,Isabelle Maurin,Solomon Saltiel,Yuanyuan Li,Arturo Lezama,Tigran Varzhapetyan,David Sarkisyan,Marie-Pascale Gorza,Michèle Fichet,Daniel Bloch,Martial Ducloy
Physics , 2005,
Abstract: The high sensitivity of Laser Spectroscopy has made possible the exploration of atomic resonances in newly designed "nanometric" gas cells, whose local thickness varies from 20nm to more than 1000 nm. Following the initial observation of the optical analogous of the coherent Dicke microwave narrowing, the newest prospects include the exploration of long-range atom surface van der Waals interaction with spatial resolution in an unprecedented range of distances, modification of atom dielectric resonant coupling under the influence of the coupling between the two neighbouring dielectric media, and even the possible modification of interatomic collisions processes under the effect of confinement.
Positive Career Attitudes Effect on Happiness and Life Satisfaction by Master Students and Graduates  [PDF]
Senad Karavdic, Michèle Baumann
Open Journal of Social Sciences (JSS) , 2014, DOI: 10.4236/jss.2014.28003

Background: Happiness and life satisfaction are well-known indicators. However, there has been little contribution by the scientific community on the positive career attitudes of master students and graduates. In an effort to provide deeper empirical understanding, the relationships between positive career attitudes, health satisfaction, financial situation and happiness and life satisfaction among master students and graduates were analyzed. Method: A link of online questionnaire was sent by mail to all students which independently of their social economic status obtained a financial aid from the government of Luxembourg, and to all master graduates (ex-students) who have been finished with their courses for one year. The data was analyzed using bivariate tests, correlation and multiple linear regression models. Result: 455 voluntary postgraduate/master students vs. 144 graduates participated. Students were younger than the graduates (mean age 26 vs. 29 years). Majority was female and had Luxembourgish nationality. Most graduates had a job and lived with their parents. Luxembourg natives were happier, and those who were living with their parents showed higher life satisfaction. For both samples, self-rated health satisfaction was positively associated with happiness and life satisfaction. For the students, the higher career adaptability and career optimism are, the better the happiness and life satisfaction will be. The higher the perception of the household financial situation is, the better the happiness will be. For graduates, the higher career optimism contributed to the better happiness. Conclusion: Happiness and life satisfaction of master students and graduates were affected, related to socioeconomic and perceived health difficulties, and career attitudes. Those indicators could be used routinely to monitor the situation of young people over time and their needs in terms of adaptability and optimism capabilities, which should be appropriately treated. These findings may help with the development of university and post university interventions aimed at improving happiness and life satisfaction among postgraduate students and ex-students.

Removal of Phenol from Aqueous Solution by Activated Mud  [PDF]
Zohra Dali-Youcef, Michèle Queneudec
Journal of Encapsulation and Adsorption Sciences (JEAS) , 2011, DOI: 10.4236/jeas.2011.13006
Abstract: Activated mud has been employed to remove phenolic compounds, a common contaminant in wastewaters. Because of high surface area per unit area, activated mud is the most effective adsorbent and exhibits high capacity of adsorption of phenolic compounds. A complete study was undertaken on the adsorption of phenol starting from an aqueous solution on activated mud with ammonium chloride. The removal is found to be dependent on concentration of phenol and increasing of concentrations favour the uptake. The isotherms and kinetics of adsorption of phenol on activated mud were studied at 20oC. Equilibrium isotherm of phenol on activated mud is obtained and the results shows that the Langmuir model provided the best fit for the adsorption data. From the experimental results obtained, the adsorption process can be well described with the pseudo-second order model.
Psychological quality of life and employability skills among newly registered first-year students: Opportunities for further university development  [PDF]
Michèle Baumann, Senad Karavdic, Nearkasen Chau
Health (Health) , 2013, DOI: 10.4236/health.2013.53A082

In accord with new European university reforms initiated by the Bologna Process, our objective was to evaluate influences on the relationship between psychological quality of life (QoL) and the acquisition of academic employability skills (AES) among first-year students at the University in Luxembourg. At the beginning (2 months in) and the end (9 months) of the academic year, 973 newly registered students participated in this study involving two cross-university surveys. Students who redoubled or who had studied at other universities were excluded. Data were collected with an online questionnaire comprising the psychological Whoqol-bref subscale, AES scale, and questions about other related factors. The AES score decreased from 74.2 to 65.6. At both time points, the psychological Whoqol-bref was positively correlated with environmental and social relations QoL and perceived general health. Multiple regression models including interaction terms showed that a higher psychological QoL was associated with better general health (difference satisfied-dissatisfied 9.44), AES (slope 0.099), social relationships QoL (0.321), and environmental QoL (0.298). No interaction with time effects was significant, which indicates that the effects remain stable with time. If the university could maintain the QoL indicators at appropriate levels or manage decreases as they occur, it would have implications for health promotion and the creation of new student support systems. The SQA- LES project provides valuable information for universities aiming to develop a European Higher Educational Area.

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