Compression of extreme-ultraviolet ultrashort pulses by grating configurations

The design and realization of grating instruments to condition the spectral phase of ultrashort extreme-ultraviolet pulses are discussed. The main application of such configurations is the temporal compression of pulses by compensating the phase chirp and getting close to the Fourier limit. We discuss the two configurations useful for the realization of ultrafast grating compressors, namely, the classical diffraction mount and the off-plane one. The configuration may be applied to free-electron lasers and high-order laser harmonics

Design study of time-preserving grating monochromators for ultrashort pulses in the extreme-ultraviolet and soft X-rays

The design of grating-based instruments to handle and condition coherent ultrafast pulses in the extreme-ultraviolet is discussed. The main application of such instruments is the monochromatization of high-order laser harmonics and free-electron-laser pulses in the femtosecond time scale. Broad-band monochromators require the use of diffraction gratings at grazing incidence. A grating can be used for the spectral selection of ultrashort pulses without altering the pulse duration in a significant way, provided that the number of illuminated grooves is equal to the resolution. We discuss here the design conditions to be fulfilled by a grating monochromator that does not increase the pulse duration significantly longer than the Fourier limit

MIGRATIONS AND DETERMINANTS OF REMITTANCES TO SOUTHERN MEDITERRANEAN COUNTRIES: WHEN HISTORY MATTERS !

In this paper we analyze the main determinants of migrant's remittances by measuring directly the role of non observable variables related to subjective motivations and historical context of the emigration process. Subjective variables, such as attachment feeling and intent to return to the country of origin can also play a role in explaining the final uses of remittances. We have used two surveys in order to understand the types of behaviour linked to remittances from France to Southern Mediterranean countries and to Sub-Saharan Africa. The first survey used in this paper is a new DREES survey on the track and the profile of migrants and the second one is the 2MO survey which we have conducted in French post offices. Our first result shows that, after controlling for all the variables linked to income, education, age or nationality, subjective variables such as to the home country, history and the institutional context of emigration play a determinant role in explaining remittance behaviour. Our second result shows that migrants, who are in France for a long time and who have low education levels, also send remittances in order to invest (including investments other than housing) in their home country. These findings contradict the theoretical hypothesis of an alteration of the migrant's links with the home country as the duration of the stay in the host country increases. This can be explained by the fact that the duration of stay does not make any sense unless it is contextualized in the history of emigration, the conditions of arrival in the host country and the conditions of departure from the home country. The degree of the migrant's attachment to his home country thus appears as a discriminating subjective variable according to these historical conditions. By contrast, the migrants from Sub-Saharan African countries send money for current expenditures rather than for investment. The obligation feeling seems to be the important subjective variable for remitting money.Subjective variables ; attachment ; remitting decision ; multivariate probit ; modelisation

Determinants and Uses of Remittances to Southern and Eastern Mediterranean Countries: Insights from a New Survey

In this paper, we analyze the determinants and the final use of remittances of migrants settled in France sending remittances to the southern Mediterranean and Sub-Saharan African countries. Research using microdata is very scarce in this region; we rely on a specially designed survey (2MO) we conducted in 2007-2008 of 1,000 people who remit to the three Maghreb countries, to Turkey and to the countries of Sub-Saharan Africa. We also use a second survey conducted by the French Ministry of Social Affairs and Health (DREES) which includes a sample of 3,500 people from the regions we are interested in. DREES microdata set enables us to understand who is more likely to remit (extensive margin). 2MO microdata allows an analysis of remittance behavior amongst those who remit (intensive margin) including sum and reported final use of remittances (housing, investment, current expenditures). Using these two microdatasets, we examine the likelihood to remit across the different waves of immigrants, the motivations to remit and the intended final use of remittances to highlight behavior differences between the different waves of immigration on the one hand, and on the other hand, the importance of looking beyond classical variables to better understand remittance behavior and its changing nature. Our first result shows that, after controlling for all the variables linked to income, education, age or nationality, subjective variables such as attachment to the home country, history and the institutional context of emigration play a determinant role in explaining remittance behavior. Our second result shows that migrants, who are in France for a long time and who have low education levels, also send remittances in order to invest in their home country. The degree of the migrant’s attachment to his home country thus appears as a discriminating subjective variable. By contrast, the migrants from Sub-Saharan Africa send money for current In this paper, we analyze the determinants and the final use of remittances of migrants settled in France sending remittances to the southern Mediterranean and Sub-Saharan African countries. Research using microdata is very scarce in this region; we rely on a specially designed survey (2MO) we conducted in 2007-2008 of 1,000 people who remit to the three Maghreb countries, to Turkey and to the countries of Sub-Saharan Africa. We also use a second survey conducted by the French Ministry of Social Affairs and Health (DREES) which includes a sample of 3,500 people from the regions we are interested in. DREES microdata set enables us to understand who is more likely to remit (extensive margin). 2MO microdata allows an analysis of remittance behavior amongst those who remit (intensive margin) including sum and reported final use of remittances (housing, investment, current expenditures). Using these two microdatasets, we examine the likelihood to remit across the different waves of immigrants, the motivations to remit and the intended final use of remittances to highlight behavior differences between the different waves of immigration on the one hand, and on the other hand, the importance of looking beyond classical variables to better understand remittance behavior and its changing nature. Our first result shows that, after controlling for all the variables linked to income, education, age or nationality, subjective variables such as attachment to the home country, history and the institutional context of emigration play a determinant role in explaining remittance behavior. Our second result shows that migrants, who are in France for a long time and who have low education levels, also send remittances in order to invest in their home country. The degree of the migrant’s attachment to his home country thus appears as a discriminating subjective variable. By contrast, the migrants from Sub-Saharan Africa send money for current expenditures rather than for investment. The obligation feeling seems to be the important motivation for remit.

Organização formal dos partidos políticos brasileiros. (2010-2015)

Anais do IV Encontro de Iniciação Científica da Unila - “UNILA 5 anos: Integração em Ciência, Tecnologia e Cultura na Tríplice Fronteira” - 05 e 06 de novembro de 2015 – Sessão Ciência Política, Sociologia, Filosofia e AntropologiaO presente trabalho traz como objetivo a realização de um mapeamento da organização formal dos partidos políticos brasileiros registrados no período de 2010 a primeira metade de 2015. Mapeamento que foi realizado com base em conceitos teóricos trazidos por autores clássicos da ciência política que realizam uma teorização sobre a organização formal dos partidos políticos, autores estes tais como, Sartori, Duverge e Panebianco. A presente pesquisa busca trazer esses conceitos teóricos apresentados pelos autores mencionados anteriormente e fazer uma análise empírica, desenvolvendo assim a relação entre o teórico com o empírico. Se ressalta que o trabalho realiza o mapeamento dos 32 partidos devidamente registrados no TSE no ano de 2014. Foi utilizado como fonte da pesquisa o próprio site do TSE, sites dos próprios partidos e também reportagens de notícias e jornais que se relacionavam com alguns partidos envolvidos na análise. O trabalho se baseia na hipótese de que os partidos políticos são organizados de acordo com sua posição ideológica, ou seja, o fato do partido ser de esquerda, direita ou centro influenciaria na forma de organização dos partidos.Pesquisador e Bolsista da Fundação Araucári

On the peer review reports: It's not the size that matters ... really?

Scientometers and sociologists of science have spilled much ink on the topic of peer review over the past twenty years, given its primordial role in a context marked by the exponential growth of scientific production and the proliferation of predatory journals. Although the topic is addressed under different prisms, few studies have empirically analyzed to what extent it can affect the quality of publications. Here we study the link between the length of reviewers' reports and the citations received by publications. To do this, we used data from the Publons database (58,093 peer review reports). We have adjusted this sample to match the WoS database structure. Our regression results show that peer review positively affects the quality of publications. In other words, the more indepth (longer) the referees' reports are, the greater the publication improvements will be, resulting in an increase in citations received. This result is important from both the point of view of reviewers and that of journal's chiefseditors. Even if it is not a remunerated activity, it is important that it be more valued at least within the framework of research evaluation exercises, given its positive impact on science.Comment: 19th International Conference of the International Society for Scientometrics and Informetrics, Jul 2023, Bloomington (Indiana), United State

Accurate Stabilization Techniques for RBF-FD Meshless Discretizations with Neumann Boundary Conditions

A major obstacle to the application of the standard Radial Basis Function-generated Finite Difference (RBF-FD) meshless method is constituted by its inability to accurately and consistently solve boundary value problems involving Neumann boundary conditions (BCs). This is also due to ill-conditioning issues affecting the interpolation matrix when boundary derivatives are imposed in strong form. In this paper these ill-conditioning issues and subsequent instabilities affecting the application of the RBF-FD method in presence of Neumann BCs are analyzed both theoretically and numerically. The theoretical motivations for the onset of such issues are derived by highlighting the dependence of the determinant of the local interpolation matrix upon the boundary normals. Qualitative investigations are also carried out numerically by studying a reference stencil and looking for correlations between its geometry and the properties of the associated interpolation matrix. Based on the previous analyses, two approaches are derived to overcome the initial problem. The corresponding stabilization properties are finally assessed by succesfully applying such approaches to the stabilization of the Helmholtz-Hodge decomposition

A hill full of points in terra incognita from Patagonia: notes and reflections for discussing the way and tempo of initial peopling

We present the environmental and archeological results of research at Cerro Amigo Oeste, a mesa-top archeological site with Fishtail points located on the Somuncurá Plateau, northern Patagonia, Argentina. Comparison with other South American sites is used to interpret archeological landscapes of colonization. The objects, features, and beings of landscape are understood as reflecting the materiality of social relations as well as patterns of production, retooling, and mobility. Cerro Amigo Oeste is in a very special location due to its high elevation and extensive view of the landscape, as well as its archeological and ethnographic significance. It can be considered a node or hub of communication in the social network among hunter-gatherers far and near in the late Pleistocene.Facultad de Ciencias Naturales y Muse