Nonlinear kinetic estimate of Raman reflectivity in a hohlraum plasma with a radiation hydrodynamics code.

In this Letter, we introduce an inline model for stimulated Raman scattering (SRS), which runs on our radiation hydrodynamics code troll. This model accounts for nonlinear kinetic effects and for the SRS feedback on the plasma hydrodynamics. We dubbed it PIEM because it is a fully "PredIctivE Model," because no free parameter is to be adjusted a posteriori in order to match the experimental results. PIEM predictions are compared against experimental measurements performed at the Ligne d'Intégration Laser. From these comparisons, we discuss the PIEM ability to correctly catch the impact of nonlinear kinetic effects on SRS.

Bremsstrahlung cannon design for shock ignition relevant regime.

We report on the optimization of a BremsStrahlung Cannon (BSC) design for the investigation of laser-driven fast electron populations in a shock ignition relevant experimental campaign at the Laser Megajoule-PETawatt Aquitaine Laser facility. In this regime with laser intensities of 1015 W/cm2-1016 W/cm2, fast electrons with energies ≤100 keV are expected to be generated through Stimulated Raman Scattering (SRS) and Two Plasmon Decay (TPD) instabilities. The main purpose of the BSC in our experiment is to identify the contribution to x-ray emission from bremsstrahlung of fast electrons originating from SRS and TPD, with expected temperatures of 40 keV and 95 keV, respectively. Data analysis and reconstruction of the distributions of x-ray photons incident on the BSC are described.

Laser-driven shock waves studied by x-ray radiography.

Multimegabar laser-driven shock waves are unique tools for studying matter under extreme conditions. Accurate characterization of shocked matter is for instance necessary for measurements of equation of state data or opacities. This paper reports experiments performed at the LULI facility on the diagnosis of shock waves, using x-ray-absorption radiography. Radiographs are analyzed using standard Abel inversion. In addition, synthetic radiographs, which also take into account the finite size of the x-ray source, are generated using density maps produced by hydrodynamic simulations. Reported data refer to both plane cylindrical targets and hemispherical targets. Evolution and deformation of the shock front could be followed using hydrodynamic simulations.

Experimental Evidence of Backward Raman Scattering Driven Cooperatively by Two Picosecond Laser Pulses Propagating Side by Side.

This Letter investigates experimentally the backward stimulated Raman scattering (SRS) of two copropagating, 1-µm wavelength, 1.5-ps duration laser pulses focused side by side, but not simultaneously, in a preformed underdense plasma. When the two lasers do not interact, one of the pulses (so-called strong) yields a large SRS reflectivity, while the other weak pulse is essentially ineffective as regards SRS. By contrast, the weak pulse shows significant SRS activity if it is launched in the plasma slightly after the strong one, and for time delays as large as about 15 ps. For crossed polarizations and a lateral distance of 80-90 µm, the time delay has to be larger than 3-4 ps for the weak pulse to be active, while it has just to be positive when the polarizations are parallel. The experimental results are discussed with the help of large-scale particle-in-cell simulations.

Publisher's Note: Experimental investigation of stimulated Raman and Brillouin scattering instabilities driven by two successive collinear picosecond laser pulses [Phys. Rev. E 93, 043209 (2016)].

This corrects the article DOI: 10.1103/PhysRevE.93.043209.

Experimental investigation of stimulated Raman and Brillouin scattering instabilities driven by two successive collinear picosecond laser pulses.

Backward stimulated Raman and Brillouin scattering (SRS and SBS) are experimentally investigated by using two successive 1-µm, 1.5-ps FWHM laser pulses. The collinear pulses, separated by 3 or 6 ps and of moderate laser intensities (∼2×10^{16}Wcm^{-2}), are fired into a preionized He plasma of density ∼2.5-6×10^{19}cm^{-3}. The electron plasma waves and ion acoustic waves, respectively driven by SRS and SBS, are analyzed through space- and time-resolved Thomson scattering. Depending on the laser and plasma parameters, we observe the effect of the first pulse on the time-resolved SRS and SBS signals of the second pulse. The measurements are found to qualitatively agree with the results of a large-scale particle-in-cell simulation.

First set of gated x-ray imaging diagnostics for the Laser Megajoule facility.

The Laser Megajoule (LMJ) facility located at CEA/CESTA started to operate in the early 2014 with two quadruplets (20 kJ at 351 nm) focused on target for the first experimental campaign. We present here the first set of gated x-ray imaging (GXI) diagnostics implemented on LMJ since mid-2014. This set consists of two imaging diagnostics with spatial, temporal, and broadband spectral resolution. These diagnostics will give basic measurements, during the entire life of the facility, such as position, structure, and balance of beams, but they will also be used to characterize gas filled target implosion symmetry and timing, to study x-ray radiography and hydrodynamic instabilities. The design requires a vulnerability approach, because components will operate in a harsh environment induced by neutron fluxes, gamma rays, debris, and shrapnel. Grazing incidence x-ray microscopes are fielded as far as possible away from the target to minimize potential damage and signal noise due to these sources. These imaging diagnostics incorporate microscopes with large source-to-optic distance and large size gated microchannel plate detectors. Microscopes include optics with grazing incidence mirrors, pinholes, and refractive lenses. Spatial, temporal, and spectral performances have been measured on x-ray tubes and UV lasers at CEA-DIF and at Physikalisch-Technische Bundesanstalt BESSY II synchrotron prior to be set on LMJ. GXI-1 and GXI-2 designs, metrology, and first experiments on LMJ are presented here.

Density and temperature characterization of long-scale length, near-critical density controlled plasma produced from ultra-low density plastic foam.

The ability to produce long-scale length (i.e. millimeter scale-length), homogeneous plasmas is of interest in studying a wide range of fundamental plasma processes. We present here a validated experimental platform to create and diagnose uniform plasmas with a density close or above the critical density. The target consists of a polyimide tube filled with an ultra low-density plastic foam where it was heated by x-rays, produced by a long pulse laser irradiating a copper foil placed at one end of the tube. The density and temperature of the ionized foam was retrieved by using x-ray radiography and proton radiography was used to verify the uniformity of the plasma. Plasma temperatures of 5-10 eV and densities around 10(21) cm(-3) are measured. This well-characterized platform of uniform density and temperature plasma is of interest for experiments using large-scale laser platforms conducting High Energy Density Physics investigations.

The schistosome glutathione S-transferase P28GST, a unique helminth protein, prevents intestinal inflammation in experimental colitis through a Th2-type response with mucosal eosinophils.

Intestinal helminth parasites are potent inducers of T helper type 2 (Th2) response and have a regulatory role, notably on intestinal inflammation. As infection with schistosomes is unlikely to provide a reliable treatment of inflammatory bowel diseases, we have investigated the beneficial effect of a schistosome enzymatic protein, the 28-kDa glutathione S-transferase (P28GST), on the modulation of disease activity and immune responses in experimental colitis. Our results showed that immunization with recombinant P28GST is at least as efficient as established schistosome infection to reduce colitis lesions and expression of pro-inflammatory cytokines. Considering underlying mechanisms, the decrease of inflammatory parameters was associated with the polarization of the immune system toward a Th2 profile, with local and systemic increases of interleukin (IL)-13 and IL-5. Dense eosinophil infiltration was observed in the colons of P28GST-immunized rats and mice. Depletion of eosinophils by treatment with an anti-Siglec-F monoclonal antibody and use of IL-5-deficient mice led to the loss of therapeutic effect, suggesting the crucial role for eosinophils in colitis prevention by P28GST. These findings reveal that immunization with P28GST, a unique recombinant schistosome enzyme, ameliorates intestinal inflammation through eosinophil-dependent modulation of harmful type 1 responses, representing a new immuno-regulatory strategy against inflammatory bowel diseases.

Experiment in planar geometry for shock ignition studies.

The capacity to launch a strong shock wave in a compressed target in the presence of large preplasma has been investigated experimentally and numerically in a planar geometry. The experiment was performed on the LULI 2000 laser facility using one laser beam to compress the target and a second to launch the strong shock simulating the intensity spike in the shock ignition scheme. Thanks to a large set of diagnostics, it has been possible to compare accurately experimental results with 2D numerical simulations. A good agreement has been observed even if a more detailed study of the laser-plasma interaction for the spike is necessary in order to confirm that this scheme is a possible alternative for inertial confinement fusion.

Enhanced isochoric heating from fast electrons produced by high-contrast, relativistic-intensity laser pulses.

Thin, mass-limited targets composed of V/Cu/Al layers with diameters ranging from 50 to 300 microm have been isochorically heated by a 300 fs laser pulse delivering up to 10 J at 2x10{19} W/cm{2} irradiance. Detailed spectral analysis of the Cu x-ray emission indicates that the highest temperatures, of the order of 100 eV, have been reached when irradiating the smallest targets with a high-contrast, frequency-doubled pulse despite a reduced laser energy. Collisional particle-in-cell simulations confirm the detrimental influence of the preformed plasma on the bulk target heating.

[Management of patients with hepatitis C by French psychologists and psychiatrists: a practical investigation]. / Prise en charge des patients atteints d'hépatites C par les psychiatres et les psychologues: une enquête de pratique.

INTRODUCTION: A first part of this survey showed that up to 19% of patients with hepatitis C virus did not receive optimal treatment because of a psychiatric problem (psychiatric disorders or addictive behaviours) and that less than 50% of the managing clinicians worked with a psychiatrist or a psychologist in these cases. The aim of the second part of the survey was to describe the current practices provided by the psychiatrists and the psychologists to HCV infected patients as well as the knowledge and expectations of professionals in this area. PATIENTS AND METHODS: Forty-seven psychiatrists and 43 psychologists who were or were not working with French reference poles for hepatitis C virus responded to a questionnaire of their practices. RESULTS: Analysis of the 90 questionnaires showed that psychiatric and/or psychological care was not systematic. Psychiatrists and psychologists should be given more information and specific training about this topic. CONCLUSION: Psychiatric and psychological care of chronic hepatitis C virus infected patients should be improved. French reference poles should also become "references" for psychiatric care.

[Impact of the mode of arrival in the emergency department for patients with a STEMI and the clinical outcomes in terms of ejection fraction and survival]. / Impact du mode d'arrivée aux urgences chez les patients avec un syndrome coronarien aigu avec elevation du segment ST (SCAST+) sur le devenir clinique en termes de FEVG et de survie.

Emergency Medical Services (EMSs) play a key role in the recognition and treatment of ST-segment elevation myocardial infarction (STEMI). This study evaluates patient outcome according to his mode of arrival in the care unit dealing with acute coronary syndromes. METHODS: Retrospective analysis of STEMI infarctions registered by the Belgian Interdisciplinary Working Group on Acute Cardiology (BIWAC) at Saint-Pierre University Hospital, Brussels (C.H.U. Saint-Pierre), between 01/01/2005 and 31/12/2006. Comparison of two groups according to their arrival in the care system: group 1: brought in following an emergency call by mobile medical team (SMUR) or normal ambulance ; group 2: arrived at the hospital by their own means and classic admission to Emergency Service. STUDIED PARAMETERS: descriptive patient characteristics, localisation of the infarction and survival to the end of hospitalization, to six months and to one year. RESULTS: Among 136 patients, 56.6 % arrived by EMS and 43.4 % by their own means. Patients who arrived by EMS were older (p = 0.008) and had a higher Killip score (p < 0.05). Pain-to-Angiography and Door-to-Angiography intervals were shorter in patients who arrived by EMS (222 vs 416 mins, p < 0.0001 and 62.6 vs 147 mins, p < 0.0001, respectively). There were no differences in the left ventricular ejection fraction (LVEF) and survival. However, for patients suffering an IVA attack, survival to six months and one year was better in the EMS group (88.9% vs 78.3%, p < 0.05 and 80.5 % vs 69.6 %, p = 0.05). In conclusion, dealing with STEMI infarctions is quicker by EMS admission. The infarctions admitted by this way are more serious. Wherever STEMI infarctions were localised, no improvement of LV function and survival was observed according to the mode of arrival, contrary to the subgroup with an IVA attack where survival is better at six months and one year by EMS admission.

Experimental evidence of predominantly transverse electron plasma waves driven by stimulated Raman scattering of picosecond laser pulses.

We report on highly time- and space-resolved measurements of the evolution of electron plasma waves driven by stimulated Raman scattering of a picosecond, single laser speckle propagating through a preformed underdense plasma. Two-dimensional Thomson scatter spectra indicate that the dominant waves have significant transverse components. These results are supported by particle-in-cell simulations which pinpoint the dominant role of the wave front bowing and of secondary nonlinear electrostatic instabilities in the evolution of the plasma waves.

Enhanced hot-electron localization and heating in high-contrast ultraintense laser irradiation of microcone targets.

We report experiments demonstrating enhanced coupling efficiencies of high-contrast laser irradiation to nanofabricated conical targets. Peak temperatures near 200 eV are observed with modest laser energy (10 J), revealing similar hot-electron localization and material heating to reduced mass targets (RMTs), despite having a significantly larger mass. Collisional particle-in-cell simulations attribute the enhancement to self-generated resistive (approximately 10 MG) magnetic fields forming within the curvature of the cone wall, which confine energetic electrons to heat a reduced volume at the tip. This represents a different electron confinement mechanism (magnetic, as opposed to electrostatic sheath confinement in RMTs) controllable by target shape.

Management of psychiatric disorders and addictive behaviors in patients with viral hepatitis C in France.

INTRODUCTION: Guidelines concerning the management of psychiatric disorders and addictive behaviors in patients with chronic hepatitis C and the conditions of collaboration between hepatogastroenterologists, infectiologists, psychiatrists and psychologists have not been published. This has a negative influence on optimal therapeutic management of chronic hepatitis C virus (HCV) infection. The aim of this study was to describe the current clinical practices for ambulatory management of psychiatric disorders and addictions, and the influence of a possible psychiatric and/or psychological collaboration. PATIENTS AND METHODS: A retrospective survey was conducted among 101 clinicians treating patients with chronic hepatitis C. Data were collected from personal interviews with the managing clinicians and from the files of patients with chronic hepatitis C patients who presented psychiatric disorders. RESULTS: Analysis of the 101 interviews and 598 patient files showed that 19% of patients had not received an optimal treatment for their HCV infection because of a psychiatric problem, and that less than 50% of the managing clinicians were working in collaboration with a psychiatrist or a psychologist. In conclusion, lack of collaboration between hepatogastroenterologists and psychiatrists could be deleterious for the optimal treatment of HCV infected patients. Improvement is required.

Transient development of backward stimulated Raman and Brillouin scattering on a picosecond time scale measured by subpicosecond thomson diagnostic.

The excitation and the relaxation of the plasma waves and ion acoustic waves (IAW), respectively, driven by stimulated Raman (SRS) and Brillouin (SBS) backscatterings have been experimentally investigated with short-pulse lasers. The spectra have been obtained with a 0.3 ps time resolution. It is shown that SRS develops before SBS and suddenly decays around the peak of the pump, as the IAW reaches saturation. On this short time scale, electron kinetic effects play a major role for SRS saturation, contrary to ion dynamics. These results are supported by particle-in-cell simulations.

PPARgamma as a new therapeutic target in inflammatory bowel diseases.

The peroxisome proliferator activated receptor gamma(PPARgamma) is a nuclear receptor highly expressed in the colon and playing a key role in bacterial induced inflammation. Regulation of colon inflammation by this receptor has been well demonstrated in many experimental models of colitis but also in patients with ulcerative colitis, characterised by impaired expression of PPARgamma confined to their colon epithelial cells. Recent data showing that PPARgamma was the major functional receptor mediating the common aminosalicylate activities in inflammatory bowel diseases (IBD) have also reinforced the roles of this receptor in the control of intestinal inflammation. The aims of this review are to discuss the potential roles of PPARgamma in the physiopathology of IBD, as well as the emerging therapeutic strategies targeting this receptor.

Fast-electron transport and heating of solid targets in high-intensity laser interactions measured by K alpha fluorescence.

We present experimental results on fast-electron energy deposition into solid targets in ultrahigh intensity laser-matter interaction. X-ray K alpha emission spectroscopy with absolute photon counting served to diagnose fast-electron propagation in multilayered targets. Target heating was measured from ionization-shifted K alpha emission. Data show a 200 microm fast-electron range in solid Al. The relative intensities of spectrally shifted Al K alpha lines imply a mean temperature of a few tens of eV up to a 100 microm depth. Experimental results suggest refluxing of the electron beam at target rear side. They were compared with the predictions of both a collisional Monte Carlo and a collisional-electromagnetic, particle-fluid transport code. The validity of the code modeling of heating in such highly transient conditions is discussed.

Measurement of the dispersion of thermal ion-acoustic fluctuations in high-temperature laser plasmas using multiple-wavelength Thomson scattering.

The dispersion of ion-acoustic fluctuations has been measured using a novel technique that employs multiple color Thomson-scattering diagnostics to measure the frequency spectrum for two separate thermal ion-acoustic fluctuations with significantly different wave vectors. The plasma fluctuations are shown to become dispersive with increasing electron temperature. We demonstrate that this technique allows a time resolved local measurement of electron density and temperature in inertial confinement fusion plasmas.