Les PME de l’industrie manufacturière en France un positionnement intermédiaire par rapport à huit autres pays européens.

Les PME de l’industrie manufacturière en France disposent d’un bon niveau de fonds propres, et sont faiblement endettées. Les délais de paiement pèsent davantage que dans les PMI allemandes et leur rentabilité est en retrait.PMI, fonds propres, endettement, délais de paiement, rentabilité, comparaisons européennes, BACH.

Dynamic ion structure factor of warm dense matter

The dynamics of the ion structure in warm dense matter is determined by molecular dynamics simulations using an effective ion-ion potential. This potential is obtained from ab initio simulations and has a strong short-range repulsion added to a screened Coulomb potential. Models based on static or dynamic local field corrections are found to be insufficient to describe the data. An extended Mermin approach, a hydrodynamic model, and the method of moments with local constraints are capable of reproducing the numerical results but have rather limited predictive powers as they all need some numerical data as input. The method of moments is found to be the most promising

La situation des PME en 2009 : leur structure financière résiste à la crise.

La crise a davantage affecté les résultats des PME en 2009 que leur structure financière. Les disparités entre PME restent fortes, avec un nombre croissant de PME défaillantes. Le décrochage de l’investissement, déjà faible avant la crise, obère les capacités de rebond à moyen terme.PME, activité, rentabilité, endettement, investissement, défaillances.

Coupled mode effects on energy transfer in weakly coupled, two-temperature plasmas

The effects of collective modes on the temperature relaxation in fully ionized, weakly coupled plasmas are investigated. A coupled mode (CM) formula for the electron-ion energy transfer is derived within the random phase approximation and it is shown how it can be evaluated using standard methods. The CM rates are considerably smaller than rates based on Fermi's golden rule for some parameters and identical for others. It is shown how the CM effects are connected to the occurrence of ion acoustic modes and when they occur. Interestingly, CM effects occur also for plasmas with very high electron temperatures; a regime, where the Landau–Spitzer approach is believed to be accurate

Dix années de dynamique financière des PME en France.

En 10 ans les PME en France ont renforcé leur structure de financement. En revanche, l’investissement apparaît faible sur les dernières années. L’image est plus favorable pour les PME adossées à un groupe, environ une sur deux désormais, qui sont en moyenne plus dynamiques que les PME indépendantes.PME, PMI, groupe d’entreprises, structure financière, comptes sociaux, financement, taux d’endettement, investissement.

Les PME-ETI cotées en bourse : la crise accentue les disparités et souligne les différences de réactivité.

Les PME-ETI cotées en bourse sont plus hétérogènes que leurs homologues non cotées en termes de dynamisme et de performance. En 2009, les plus rentables montrent une capacité de rebond supérieure.PME, ETI, bourse, taux de marge, endettement, fonds propres.

Harmonics generation in electron-ion collisions in a short laser pulse

Anomalously high generation efficiency of coherent higher field-harmonics in collisions between {\em oppositely charged particles} in the field of femtosecond lasers is predicted. This is based on rigorous numerical solutions of a quantum kinetic equation for dense laser plasmas which overcomes limitations of previous investigations.Comment: 4 pages, 4 eps-figures include

Intraspecific variability in the response of bloom-forming marine microalgae to changed climate conditions

Phytoplankton populations can display high levels of genetic diversity that, when reflected by phenotypic variability, may stabilize a species response to environmental changes. We studied the effects of increased temperature and CO2 availability as predicted consequences of global change, on 16 genetically different isolates of the diatom Skeletonema marinoi from the Adriatic Sea and the Skagerrak (North Sea), and on eight strains of the PST (paralytic shellfish toxin)-producing dinoflagellate Alexandrium ostenfeldii from the Baltic Sea. Maximum growth rates were estimated in batch cultures of acclimated isolates grown for five to 10 generations in a factorial design at 20 and 24°C, and present day and next century applied atmospheric pCO2, respectively. In both species, individual strains were affected in different ways by increased temperature and pCO2. The strongest response variability, buffering overall effects, was detected among Adriatic S. marinoi strains. Skagerrak strains showed a more uniform response, particularly to increased temperature, with an overall positive effect on growth. Increased temperature also caused a general growth stimulation in A. ostenfeldii, despite notable variability in strain-specific response patterns. Our data revealed a significant relationship between strain-specific growth rates and the impact of pCO2 on growth—slow growing cultures were generally positively affected, while fast growing cultures showed no or negative responses to increased pCO2. Toxin composition of A. ostenfeldii was consistently altered by elevated temperature and increased CO2 supply in the tested strains, resulting in overall promotion of saxitoxin production by both treatments. Our findings suggest that phenotypic variability within populations plays an important role in the adaptation of phytoplankton to changing environments, potentially attenuating short-term effects and forming the basis for selection. In particular, A. ostenfeldii blooms may expand and increase in toxicity under increased water temperature and atmospheric pCO2 conditions, with potentially severe consequences for the coastal ecosystem

Multiconfigurational time-dependent Hartree-Fock calculations for photoionization of one-dimensional Helium

The multiconfigurational time-dependent Hartree-Fock equations are discussed and solved for a one-dimensional model of the Helium atom. Results for the ground state energy and two-particle density as well as the absorption spectrum are presented and compared to direct solutions of the time-dependent Schroedinger equation.Comment: 10 pages, 3 figures, 1 tabl

A reduced coupled-mode description for the electron-ion energy relaxation in dense matter

We present a simplified model for the electron-ion energy relaxation in dense two-temperature systems that includes the effects of coupled collective modes. It also extends the standard Spitzer result to both degenerate and strongly coupled systems. Starting from the general coupled-mode description, we are able to solve analytically for the temperature relaxation time in warm dense matter and strongly coupled plasmas. This was achieved by decoupling the electron-ion dynamics and by representing the ion response in terms of the mode frequencies. The presented reduced model allows for a fast description of temperature equilibration within hydrodynamic simulations and an easy comparison for experimental investigations. For warm dense matter, both fluid and solid, the model gives a slower electron-ion equilibration than predicted by the classical Spitzer result