45 research outputs found
Les relations économiques et financières franco-allemandes, 1932-1939
No full textMalgré les clauses du traité de Versailles, le Reich a réussi, à la fin des années 20, son redressement économique. Mais la crise de 1929 révèle la fragilité financière de cette renaissance. La France, dont le stock d’or est important, refuse son concours à l’Allemagne et c’est alors que les deux pays se replient sur leurs espaces nationaux, dès avant l’arrivée au pouvoir d’Hitler. L’installation du régime nazi pose un problème crucial. Faut-il envisager avec lui des relations économiques et financières sur les mêmes bases qu’avec la République de Weimar ? Si, pour Hitler, les données sont simples - l’économie doit servir le réarmement -, il est en revanche plus difficile pour les gouvernements français de faire abstraction d’intérêts souvent contradictoires. Les responsables tentent les uns après les autres de sauver les intérêts financiers français en Allemagne en contrepartie d’avantages économiques accordés au Reich. A partir de 1938, ces décisions devront pour les uns sauver la paix, pour les autres gagner le temps nécessaire au réarmement français. Mais le répit dépendait d’Hitler! « Par la qualité et l’ampleur de la recherche, la profondeur de la réflexion, la précision de la synthèse, le caractère très neuf de conclusions solidement charpentées, cet ouvrage éclaire tout un aspect des relations franco-allemandes resté trop longtemps dans l’ombre ». Raymond PoidevinDespite the clauses contained in the Treaty of Versailles, by the end of the 1920s the Reich had managed to rebuild its economy. However, the crisis in 1929 revealed the financial fragility of this rebirth. France, which held large stocks of gold, refused to help Germany, and it was at that point that both countries withdrew into their national shells, even before Hitler came to power. The establishment of the Nazi regime raised a crucial problem. Should France envisage economic and financial relations with it on the same basis as with the Weimar Republic? Although for Hitler the facts were simple – the economy must serve rearmament -, it was on the contrary more difficult for the French governments to disregard frequently contradictory interests. Successive governments tried to safeguard French financial interests in Germany in return for economic advantages granted to the Reich. After 1938, these decisions were for some designed to save the peace and for others to gain the time needed for France to rearm. However, the respite depended on Hitler. ‘This work, through the quality and breadth of its research, the depths of reflection, the accuracy with which the author has marshalled his facts and the well-supported and highly innovative conclusions he reaches, sheds light on an entire aspect of Franco-German relations whiA pesar de las cláusulas del Tratado de Versalles, el Reich consiguió consumar su recuperación económica a finales de los años 20. La crisis de 1929 sin embargo puso de manifiesto la fragilidad financiera de este renacer. Francia, que contaba con importantes reservas de oro, rehusó ayudar a Alemania, con lo que ambos países se replegaron sobres sus respectivos espacios nacionales antes incluso de la llegada al poder de Hitler. La instauración del régimen nazi suscitaba un problema crucial. ¿Cabía plantearse unas relaciones económicas y financieras con las mismas bases que habían regido con la República de Weimar? Mientras para Hitler los datos eran simples –la economía debía servir al rearme–, para los gobiernos franceses resultaba mucho más difícil hacer abstracción de intereses a menudo contradictorios. Los sucesivos responsables intentaron salvar los intereses financieros franceses en Alemania concediendo contrapartidas económicas al Reich. A partir de 1938, estas decisiones serían vistas por unos como una forma de salvaguardar la paz, por otros como una forma de dar el tiempo necesario al rearme francés. El dar un respiro sin embargo era algo que dependía de Hitler… “La calidad y alcance de la investigación, lo profundo de la reflexión, la precisión de la síntesis y el carácter innovador de conclusiones sólidamente estructuradas hacen que el libro consiga arrojar luz sobre todo un aspecto de las relaciones franco-alemanas que durante mucho tiempo ha permanecido en la sombra” (Raymond Poidevin).Le Comité pour l’histoire économique et financière, présidé par les ministres de l’Économie et du Budget, est composé des personnalités suivantes : a. Membres de droit : Les directeurs et chefs de service des ministères de l’Économie et du Budget, le gouverneur de la Banque de France, le directeur général de la Caisse des dépôts et consignations, le directeur général des Archives de France, l’administrateur général de la Bibliothèque nationale. b. Membres désignés en raison de leur compétence : Michel Aglietta, Michel Antoine, Guy Antonetti, Françoise Bayard, Louis Bergeron, Jean-Jacques Bienvenu, Christian de Boissieu, François Caron, Patrick Fridenson, René Girault, Maurice Lévy-Leboyer, Jacques Marseille, Yves Mény, François Monnier, Gabriel Montagnier, Alain Plessis, Raymond Poidevin, Guy Thuillier, Jean Tulard, Denis Woronoff. c. Membres ès qualités : Jacques Campet, Jean-Noël Jeanneney, François Gasnault. La mission du Comité est de contribuer à une meilleure connaissance de l’histoire de l’État et de son rôle en matière économique et financière depuis le Moyen Âge jusqu’à nos jours, de susciter des travaux scientifiques et d’en aider la diffusion. Le texte de cet ouvrage est issu d'une thèse de doctorat dirigée par M. le professeur R. Poidevin, et soutenue en janvier 1994 à l'université Robert Schuman de Strasbourg. Le jury était présidé par M. le professeur F. Caron. Il se composait de MM. les professeurs R. Poidevin, F. Knipping, M. Hau et J.P. Mousson-Lestang. À tous, mes remerciements. Strasbourg, décembre 1994
Reduction and Emergence in Chemistry - Two Recent Approches.
No full textTwo articles on the reduction of chemistry are examined. The first, by McLaughlin, claims that chemistry is reduced to physics and that there is no evidence for emergence or for downward causation between the chemical and the physical level. In a more recent article Le Poidevin maintains that his combinatorial approach provides grounding for the ontological reduction of chemistry and also circumvents some limitations in the physicalist program. In examining the scientific issues that each author has discussed the present author finds some shortcomings in both of these approaches
H-poor Superluminous Supernovae surveys
No full textDiscovered about fifteen years ago H-poor Superluminous Supernovae (SLSN), or type I SLSN, are among the most luminous transients in the sky. This class of supernovae is mainly detected in low luminosity, low metallicity galaxies making them interesting tracers of this class of galaxies. SLSNe are expected to arise from massive stellar progenitors, but their nature is still not well understood. The proposed models for the SLSN power source are challenged to explain all the observations. The currently most accepted model is the central engine or magnetar model. After a brief introduction about SLSN-I and their hosts, we give a description of our SLSN surveys and present some results of a target of opportunity program conducted in 2021 from the Nordic Optical Telescope and from the Liverpool Telescope in La Palma. This survey aimed to follow-up a sample of SLSNe-I for studying 3 key time phases in their light curve evolution. By using spectroscopy, photometry and by measuring time variation of the intrinsic polarisation of SLSNe-I we retrieved information on the evolution of the structure of the transients to test the magnetar model validity. This survey increases the relatively small existing sample of polarimetry data available on such objects and sheds light on the evolution of the photosphere of such objects. The first results are published in Poidevin etal. (2022) and other publications are currently in preparation. A second polarimetry survey will start in October 2022
Parts as counterparts
No full textDate of Acceptance: 22/10/2013Mereological nihilists are faced with a difficult challenge: explaining ordinary talk about material objects. Popular paraphrase strategies involve plurals, arrangements of particles, or fictions. In this paper, a new paraphrase strategy is put forward that has distinct advantages over its rivals: it is compatible with gunk and emergent properties of macro-objects. The only assumption is a commitment to a liberal view of the nature of simples; the nihilist must be willing to accept the possibility of heterogeneous extended simples. The author suggests reinterpreting the parthood and composition relations as modal. According to this paraphrase, composition is a kind of counterpart relation. The author shows that one can accept that mereological nihilism is metaphysically necessary, while endorsing all the claims of classical mereology. As a result, the nihilists are in exactly the same position as the classical mereologist when it comes to explaining talk about ordinary objects, but without the additional ontology.Peer reviewe
The onset of large-scale turbulence in the interstellar medium of spiral galaxies
No full textDFG thanks the European Research Council (ADG-2011 ECOGAL), and Brazilian agencies CAPES (3400-13-1) and FAPESP (no.2011/12909-8) for financial support. IB acknowledges the European Research Council (ADG-2011 ECOGAL) for financial support. GK acknowledges support from FAPESP (grants no. 2013/04073-2 and 2013/18815-0).Turbulence is ubiquitous in the interstellar medium (ISM) of the Milky Way and other spiral galaxies. The energy source for this turbulence has been much debated with many possible origins proposed. The universality of turbulence, its reported large-scale driving, and that it occurs also in starless molecular clouds, challenges models invoking any stellar source. A more general process is needed to explain the observations. In this work, we study the role of galactic spiral arms. This is accomplished by means of three-dimensional hydrodynamical simulations which follow the dynamical evolution of interstellar diffuse clouds (similar to 100 cm-3) interacting with the gravitational potential field of the spiral pattern. We find that the tidal effects of the arm's potential on the cloud result in internal vorticity, fragmentation and hydrodynamical instabilities. The triggered turbulence results in large-scale driving, on sizes of the ISM inhomogeneities, i.e. as large as similar to 100 pc, and efficiencies in converting potential energy into turbulence in the range similar to 10-25 per cent per arm crossing. This efficiency is much higher than those found in previous models. The statistics of the turbulence in our simulations are strikingly similar to the observed power spectrum and Larson scaling relations of molecular clouds and the general ISM. The dependence found from different models indicate that the ISM turbulence is mainly related to local spiral arm properties, such as its mass density and width. This correlation seems in agreement with recent high angular resolution observations of spiral galaxies, e.g. M51 and M33.Peer reviewe
On the alignment of PNe and local magnetic field at the Galactic centre : magnetohydrodynamical numerical simulations
No full textDFG thanks the European Research Council (ADG-2011 ECOGAL), and Brazilian agencies CNPq (no. 300382/2008-1), CAPES (3400-13-1) and FAPESP (no.2011/12909-8) for financial support. HM thanks CNPq grant 573648/2008-5 and FAPEMIG grants APQ-02030-10 and CEX-PPM-00235-12.For the past decade, observations of the alignment of planetary nebulae (PNe) symmetries with respect to the Galactic disc have led to conflicting results. Recently, the first direct observational evidence for a real alignment between PNe and local interstellar magnetic fields in the central part of the Galaxy (b 100 μG are required in order to be dynamically dominant. This is found to occur only at later evolutionary stages, therefore, being unable to change the general morphology of the nebula. However, the symmetry axis of bipolar and elliptical nebulae end up aligned to the external field. This result can explain why different samples of PNe result in different conclusions regarding the alignment of PNe. Objects located at high Galactic latitudes, or at large radii, should present no preferential alignment with respect to the Galactic plane. PNe located at the Galactic centre and low latitudes would, on the other hand, be preferentially aligned to the disc. Finally, we present synthetic polarization maps of the nebulae to show that the polarization vectors, as well as the field lines at the expanding shell, are not uniform even in the strongly magnetized case, indicating that polarization maps of nebulae are not adequate in probing the orientation, or intensity, of the dominant external field.Peer reviewe
Uneven Power and the Pursuit of Peace: How Regional Power Transitions Motivate Integration. CES Working Paper, no. 150, 2007
No full textThis paper addresses two related puzzles confronting students of regional and international integration: Why do states willingly pool and delegate sovereignty within international institutions? What accounts for the timing and content of regional integration agreements? Most theories of integration suggest that states integrate in order to solve problems of incomplete information and reduce transaction costs and other barriers to economic growth. In contrast I argue that integration can serve to establish a credible commitment that rules out the risk of future conflict among states of unequal power. Specifically, I suggest that integration presents an alternative to preventive war as a means to preclude a rising revisionist power from establishing a regional hegemony. The implication is that it is not countries enjoying stable and peaceful relations that are most likely to pursue integration, but rather countries that find themselves caught in a regional security dilemma, which they hope to break out of by means of institutionalized cooperation. I evaluate this proposition against evidence from two historical cases of regional integration: the German Zollverein and the European Communities
Ambient magnetic field amplification in shock fronts of relativistic jets : an application to GRB afterglows
No full textGRS thanks CNPQ for financial support. DFG thanks the European Research Council (ADG-2011 ECOGAL) and the Brazilian agencies CNPq (No. 300382/2008-1), CAPES (3400-13-1) and FAPESP (No. 2011/12909-8) for financial support. GK thanks FAPESP (No. 2009/50053-8, 2011/51275-4, 2013/04073-2, 2013/18815-0) for financial support. EMGDP thanks FAPESP (No. 2006/50654-3) and CNPq (306598/2009-4) for financial support. Date of Acceptance: 06/10/2014Strong downstream magnetic fields of the order of ∼1 G, with large correlation lengths, are believed to cause the large synchrotron emission at the afterglow phase of gamma-ray bursts (GRBs). Despite the recent theoretical efforts, models have failed to fully explain the amplification of the magnetic field, particularly in a matter-dominated scenario. We revisit the problem by considering the synchrotron emission to occur at the expanding shock front of a weakly magnetized relativistic jet over a magnetized surrounding medium. Analytical estimates and a number of high-resolution 2D relativistic magnetohydrodynamical (RMHD) simulations are provided. Jet opening angles of θ = 0°–20°, and ambient to jet density ratios of 10−4–102 were considered. We found that most of the amplification is due to compression of the ambient magnetic field at the contact discontinuity between the reverse and forward shocks at the jet head, with substantial pile-up of the magnetic field lines as the jet propagates sweeping the ambient field lines. The pile-up is maximum for θ → 0, decreasing with θ, but larger than in the spherical blast problem. Values obtained for certain models are able to explain the observed intensities. The maximum correlation lengths found for such strong fields is of lcorr ≤ 1014 cm, 2–6 orders of magnitude larger than the found in previous works.Peer reviewe
