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Energy and frequency dependence of the alpha particle redistribution produced by internal kink modes
No full textInternational audienceThe redistribution of alpha particles due to internal kink modes is studied. The exact particle trajectories in the total fields, equilibrium plus perturbation, are calculated. The equilibrium has circular cross section and the plasma parameters are similar to those expected in ITER. The alpha particles are initially distributed according to a slowing down distribution function and have energies between 18 keV and 3.5 MeV. The (1, 1), (2, 2), and (2, 1) modes are included and the effect of changing their amplitude and frequency is studied. When only the (1, 1) mode is included, the spreading of high energy ( E≳1 MeV) alpha particles increases slowly with the energy and mode frequency. At lower energies, the redistribution is more sensitive to the mode frequency and particle energy. When a (2, 1) mode is added, the spreading increases significantly and particles can reach the edge of the plasma. Trapped particles are the most affected and the redistribution parameter can have maxima above 1 MeV, depending on the mode frequency. These results can have important implications for ash removal
La construction d'Abbes et Saito pour les connexions méromorphes: aspect formel en dimension 1
No full textBy using a blow-up construction, the nearby-cycle functor and l-adic Fourier transform, Abbes and Saito are able to define a geometric measure of wild ramification of l-adic sheaves on the generic point of any complete discrete valuation ring of equal characteristic p with perfect residue field, where p is different from l. In this paper, we adapt their construction to differential modules over the field of formal Laurent series with coefficients in any characteristic zero field K. For such a module M, we prove a formula relating Abbes and Saito's construction to the differential forms occuring in the Levelt-Turrittin decomposition of M. If K is algebraically closed, one recovers a version of Laurent's micro-characteristic cycles
Effect of gamma rays absorbed doses and heat treatment on the optical absorption spectra of silver ion-exchanged silicate glass
No full textInternational audienceSamples of a commercial silicate glass have been subjected to ion exchange at 320 °C in a molten mixture of AgNO 3 and NaNO 3 with molar ratio of 1:99 and 5:95 for 60 min. The ion exchange process was followed by gamma irradiation in the dose range of 1–250 kGy and heating at the temperature of 550 °C for different time periods ranging from 10 to 582 min. The spectral absorption in UV–Vis range of the Ag–Na ion exchanged glass was measured and used to determine the states of silver prevailing in the glass during the ion exchange, the gamma irradiation and the heat treatment. The gamma irradiation induced holes and electrons in the glass structure leading to the creation of a brown colour, and silver ions trapped electrons to form silver atoms. We observed the first stage of aggregation after irradiation, as well as after heating. The silver atoms diffused and then aggregated to form nanoclusters after heating at 550 °C. A characteristic band at about 430 nm was induced. The surface Plasmon absorption of silver nanoclusters in the glass indicated that the nanoclusters radius grew between 0.9 and 1.43 nm with increasing of annealing time from 10 to 242 min and then saturated. We also found that the size of aggregates depends on the value of gamma radiation absorbed dose. Contrary to what was expected, we found that 20 kGy is the optimal absorbed dose corresponding to the larger size of the aggregates which decreases for absorbed doses above 20 kGy
Diagnostic and prognostic value of serum procalcitonin concentrations in primary lung cancers.
No full textInternational audienceProcalcitonin (PCT) is widely used for the diagnosis of bacterial infections. The aim of this study was to evaluate PCT as a tumor and as a prognostic marker in patients with primary lung cancer. We retrospectively performed a PCT dosage in the frozen serum samples of 147 patients with pulmonary neoplasia for whom a test of neuron-specific enolase (NSE) had been conducted at the time of diagnosis. We show that a PCT serum level above 0.15 ng/mL was independently linked to the presence of a neuroendocrine component in the tumor (HR=5.809 95% CI [1.695-19.908] p: 0005). Thus, median PCT serum levels were significantly more elevated in small-cell lung cancers than in pulmonary adenocarcinomas: 0.33 ng/mL versus 0.07 ng/mL (p<0.001). However, the diagnostic value of serum PCT levels for diagnosing carcinoma with a neuroendocrine component remains low (sensitivity 63.8%; specificity 71.9%). In this series, serum PCT levels were significantly more elevated in the presence of liver metastases: 0.37 ng/mL versus 0.09 ng/mL in the absence of liver metastasis (p<0.001). In uni- and multivariate analyses, a serum PCT level above 0.15n g/mL and the presence of metastases and of sepsis at the time of diagnosis were independent factors of unfavorable prognosis. Serum PCT is elevated in patients with lung cancer with neuroendocrine component or with liver metastases. As a consequence, in this population, PCT has a poor specificity for bacterial infection. At diagnosis, an elevated serum PCT is an independent predictive factor of bad prognosis
Backward stimulated radiation from filaments in Nitrogen gas and air pumped by circularly polarized 800 nm femtosecond laser pulses
No full textInternational audienceWe report on strong backward stimulated emission at 337 nm in Nitrogen gas pumped by circularly polarized femtosecond laser pulses at 800 nm. A distinct dependence of the backward UV spectrum on pump laser polarization and intensity is observed, pointing to the occurrence of backward amplified spontaneous emission inside filaments. We attribute the population inversion to inelastic collision between the free electrons produced by the pump laser and neutral N 2 molecules. The addition of Oxygen molecules is detrimental for the gain, reducing it to near threshold at atmospheric concentration
Effect of an external electric field on the coherent terahertz emission from multiple filaments in air
No full textInternational audienceWe describe the terahertz emission from multiple filaments in air in the presence of an external electric field. A strong enhancement of the radiated terahertz energy is obtained by the combined effect of terahertz field interference and presence of a static electric field
Formal [3+2] cycloaddition of Ugi adducts towards pyrrolines
No full textInternational audienceUgi adducts derived from aromatic aldehydes may be converted to pyrrolines via addition of Michael acceptors under microwave irradiation. The reaction may proceed via unusual formation of azomethine ylides followed by a [3+2] cycloaddition using Michael acceptors
Response of the Martian environment to solar wind dynamic pressure change
No full textInternational audienceThe main structures of the solar wind plasma interaction with the upper atmosphere can be usually described using a steady state picture, however time-dependent effects play important roles. In the last couple of years sophisticated 3D simulation try to address the response of the induced magnetosphere and its escape to different time-dependent drivers. Modolo et al (2012) discussed about timescales required for the induced magnetosphere to recover from an IMF rotation. Ma et al (2013) used time-varying solar wind conditions (density and velocity enhancement) and concluded that the ionospheric/atmospheric system reach a new equilibrium in few hours. We use a 3D parallel multi-species hybrid simulation model to study the response of the induced magnetosphere to a time-varying solar wind dynamic pressure. The hybrid model (Modolo et al, 2014, in prep) includes crustal fields, a ionospheric chemistry scheme and uses a 3D description of the Martian thermosphere (Chaufray et al, 2014) and exosphere (Yagi et al, 2012). The impact of a solar wind dynamic pressure change on plasma boundaries is discussed. A special attention is focused on the time-varying energy deposition in the upper atmosphere by O+ ions precipitation as well as the escape flux of planetary ions
Magnetic Reconnection Controls Impacts of Solar Wind Ions at Mercury's Surface : Investigation By Global Hybrid Simulations
No full textInternational audienceMESSENGER has revealed the complexity of the Hermean magnetic field which is dominated by dipolar and quadrupolar components (Anderson et al., 2012 and references therein). By contrast to other magnetized planets having large scale dynamo driven magnetic fields Mercury has a quadrupolar field large enough to reinforce the dipolar field at high northern latitudes and to shape the topology of the planetary field in the equatorial region and the southern hemisphere. Magnetic reconnection at Mercury is extremely effective for all IMF orientations [DiBraccio et al., JGR, 2013]. Global hybrid simulations by Richer et al. (2012) have demonstrated the dramatic influence of the quadrupolar field of Mercury on the topology of the Hermean magnetosphere. Then Chanteur et al. (AOGS 2014) have investigated the impacts of solar wind protons and alphas on Mercury’s surface with the same hybrid code and have presented a case study to demonstrate the importance of magnetic reconnection between the IMF and the planetary field in this process. We will present a set of different results corresponding to different configurations depending upon the IMF orientation and solar wind parameters.ReferencesAnderson, B. J., C. L. Johnson, H. Korth, R. M. Winslow, J. E. Borovsky, M. E. Purucker, J. A. Slavin, S. C. Solomon, M. T. Zuber, and R. L. McNutt Jr. (2012), Low-degree structure in Mercury’s planetary magnetic field, J. Geophys. Res., 117, E00L12, doi:10.1029/2012JE004159.DiBraccio, G. A., J. A. Slavin, S. A. Boardsen, B. J. Anderson, H. Korth, T. H. Zurbuchen, J. M. Raines, D. N. Baker, R. L. McNutt Jr., and S. C. Solomon (2013), MESSENGER observations of magnetopause structure and dynamics at Mercury, J. Geophys. Res. Space Phys., 118, 997–1008, doi:10.1002/jgra50123.Richer, E., R. Modolo, G. M. Chanteur, S. Hess, and F. Leblanc (2012), A global hybrid model for Mercury’s interaction with the solar wind: Case study of the dipole representation, J. Geophys. Res., 117, A10228, doi:10.1029/2012JA017898.Chanteur, G.M., R. Modolo, and F. Leblanc (2014), Effect of the Hermean Magnetic quadrupole on Magnetic Reconnection and Penetration of the SW Plasma Inside the Magnetosphere, AOGS, 11th annual meeting, Sapporo, Japan, July 28th – August 1st
Fixed point of payment-free Shapley operators and structural properties of mean payoff games
No full textPosterInternational audienc