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The advent of high-power lasers facilities such as the National Ignition Facility (NIF), and Laser Megajoule (LMJ) in the near future opens a new era in the field of High Energy Density Laboratory Astrophysics. The LMJ, keystone of the French Simulation Program, is under construction at CEA/CESTA and will deliver 1.5 MJ with 176 beamlines. The first physics experiments on LMJ will be performed at the end of 2014 with 2 quadruplets (8 beams). The operational capabilities (number of beams and plasma diagnostics) will increase gradually during the following years. We describe the current status of the LMJ facility and the first set of diagnostics to be used during the commissioning phase and the first experiments. The PETAL project (PETawatt Aquitaine Laser), part of the CEA opening policy, consists in the addition of one short-pulse (500 fs to 10 ps) ultra-high-power, high-energy beam (a few kJ compressed energy) to the LMJ facility. PETAL is focalized into the LMJ target chamber and could be used alone or in combination with LMJ beams. In the later case, PETAL will offer a combination of a very high intensity multi-petawatt beam, synchronized with the nanosecond beams of the LMJ. PETAL, which is devoted to the academic research, will also extend the LMJ diagnostic capabilities. Specific diagnostics adapted to PETAL capacities are being fabricated in order to characterize particles and radiation yields that can be created by PETAL. A first set of diagnostics will measure the particles (protons/ions/electrons) spectrum (0.1–200 MeV range) and will also provide point projection proton-radiography capability. LMJ/PETAL, like previously the LIL laser [X. Julien et al., Proc. SPIE 7916 (2011) 791610], will be open to the academic community. Laboratory astrophysics experiments have already been performed on the LIL facility, as for example radiative shock experiments and planetary interiors equation of state measurements.

Since the first experimental campaign conducted in 2014 with mid field Gated X-ray Imager (GXI) and two quadruplets (20 kJ at 351 nm) focused on target, the Laser MegaJoule (LMJ) operational capability is still growing up. New plasma diagnostics have been implemented: a large field 2D GXI, two broadband x-ray spectrometers (called DMX and miniDMX), a specific soft x-ray spectrometer and a Laser Entrance Hole (LEH) imaging diagnostic. A series of experiments have been performed leading to more than 60 shots on target. We will present the plasma diagnostics development status conducted at CEA for experimental purpose. Several diagnostics are now under manufacturing or development which include a Streaked Soft X-ray Imager (SSXI), an Equation Of State (EOS) diagnostic suite (“EOS pack”), a Full Aperture BackScattering (FABS) diagnostic, a Near Backscattered Imager (NBI), a high resolution 2D GXI, a high resolution x-ray spectrometer, a specific set of two polar hard x-ray imagers for LEH characterization and a set of Neutron Time of Flight (NTOF) detectors. We describe here the diagnostics design and performances in terms of spatial, temporal and spectral resolutions. Their designs have taken into account the harsh environment (neutron yields, gamma rays, electromagnetic perturbations, debris and shrapnel) and the safety requirements.

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.

Arrive E, Letenneur L, Matharan F, Laporte C, Helmer C, Barberger-Gateau P, Miquel JL, Dartigues JF. Oral health condition of French elderly and risk of dementia: a longitudinal cohort study. Community Dent Oral Epidemiol 2011. © 2011 John Wiley & Sons A/S Abstract – Objectives: Oral condition could be associated with cognitive impairment, but this is not yet well documented. We therefore hypothesized that people with poor oral condition would be more at risk to develop dementia. The objective of this study thus was to describe the oral condition of French community-dwelling elderly persons and to assess its relationship with the occurrence of dementia. Methods: Oral examination was conducted on a sample of individuals aged 66–80 years followed-up prospectively for screening of dementia over 15 years in Gironde, France. Univariate and multivariate analyses of the risk of dementia were performed using a Cox proportional hazard model with delayed entry. Results: Data from 405 individuals were analyzed; 45.4% men; median age at baseline: 70 years [interquartile range (IQR): 68–75]. The median number of decayed, missing, and filled teeth was 18 (IQR: 13–24) and was higher in women (median: 20 versus 17, P = 0.004) and in persons with lower school level (median: 21 versus 17, P = 0.003). Among 348 persons with sextant eligible for periodontal assessment, 2/3 required periodontal care: 5.2% had bleeding observed, 44.8% calculus, 17.8% 4–5 mm pockets, and 2.9%≥6 mm pockets. The incidence of dementia during a median follow-up of 10 years (IQR: 6.5–13.7) was 19 per 1000 person-years. The adjusted hazard ratio for a number of missing teeth≥11 (median) on the risk of dementia was 1.13 (95% confidence interval, CI = [0.60–2.12]) in people with higher education (n = 312) and 0.30 (CI = 0.11–0.79) in persons with lower school level (n = 93) (P for modification effect = 0.0002). Conclusions: Having eleven or more missing teeth seemed to be associated with a lower risk of dementia in people with lower education possibly owing to the suppression of source of chronic inflammation.

By frequency-doubling the long pre-forming pulse in the now well-known transient collisional excitation (TCE) scheme, a two-color (2ω/1ω) pumping of the nickel-like silver x-ray laser (XRL) has been investigated both experimentally and theoretically. The angular XRL characteristics have been studied and compared to standard (1ω/1ω) and inverse 2-color (1ω/2ω) irradiations. Through a statistical treatment of the recorded data, a significant reduction of the beam divergence has then been noticed. Moreover, the influence of the required traveling wave irradiation on the amplification duration has been checked, the observed shortening being explained by either a simple propagation model or more sophisticated simulations.

Today, one of the key applications for X-ray Lasers is ICF-relevant plasma density diagnostics through interferometry techniques. Due to the peak reflectivity of the involved Mo/Si multilayer optics, the CEA/DAM studies have been focused on collisionnally excited population inversions in Ni-like silver plasmas. In order to optimize their X-ray output at 139 A, various configurations have been investigated. One of them has recently been demonstrated at the P102 facility and has allowed 1011 photons per pulse to be delivered, i.e. 2 μJ in 7 ps.

A detailed investigation of many aspects of the physics of laser–plasma interaction at very high laser intensities is required in order to assess the feasibility and the promise of the fast ignitor scheme for inertial confinement fusion. Relevant results, obtained in a series of experiments carried out at the Rutherford Appleton Laboratory, Chilton (UK) and at the Centre d'Etudes Atomique, Limeil Valenton (France), are presented and discussed here. In particular, the formation of plasma channels was observed following the propagation of relativistically intense, ps laser pulses through underdense plasmas. The channels persist long after the interaction, and their expansion has been measured. Efficient guiding of ultraintense laser pulses, both through preformed density channels and through solid guides, has been demonstrated. Finally, indication of collimated fast electron propagation through solid targets has been obtained from the observation of filamentary ionization tracks in laser irradiated solid targets.

Laser imprinting has been studied and, in particular, saturation of areal density perturbations induced by near single mode laser imprinting was observed. Several issues important for the foam buffered direct drive scheme have been investigated. These studies included measurements of the absolute levels of stimulated Brillouin and Raman scattering observed from laser irradiated low density foam targets, either bare or overcoated with a thin layer of gold. A novel scheme is proposed to increase the pressure in indirectly driven targets. By heating a foam supersonically that is attached to a solid target the pressure generated is not only the ablation pressure but also the combined pressure due to ablation at the foam-foil interface and the heated foam material. Planar brominated plastic foil targets overcoated with a low density foam were irradiated by a soft X ray pulse. The pressure was obtained by comparing the rear side trajectory of the driven target observed by soft X ray radiography with one dimensional radiation hydrodynamic simulations. Observations were also carried out of the transition from supersonic to subsonic propagation of an ionization front in low density chlorinated foam targets irradiated by an intense soft X ray pulse. The diagnostic for these measurements was K shell point projection absorption spectroscopy. In the fast ignitor area the channelling and guiding of picosecond laser pulses through underdense plasmas, preformed density channels and microtubes were investigated. It was observed that a large fraction of the incident laser energy can be propagated. Megagauss magnetic fields were measured, with a polarimetric technique, during and after propagation of intense picosecond pulses in preionized plasmas. Two types of toroidal fields, of opposite orientation, were detected. In addition, the production and propagation of an electron beam through solid glass targets irradiated at intensities above 1019W/cm2 were observed using optical probing techniques.

Propagation of a high-contrast subpicosecond (400–600 fs) relativistic (Iλ2 up to 2×1019 W⋅cm−2⋅μm2) laser pulse through long preformed overdense plasmas is experimentally studied. Transmission values up to 10% are measured in plasmas with initial peak densities above 10×nc. We compare these results with one-dimensional (1D) analytical calculations of the hole boring effect. It is shown that the ponderomotive force of the laser beam can push forward the overdense plasma, create a channel, and lead to transmission levels similar to the experimental ones.

Propagation of a high-contrast frequency-doubled subpicosecond (300 fs) relativistic (Iλ2 up to 5×1018 W⋅cm−2⋅μm2) laser pulse through thin and initially solid foils is studied. Transmission values up to 10% are measured through targets with initial near solid densities. The strong intensity threshold observed for the transmitted energy is correlated with clear modifications of the transmitted and reflected spectra, electron generation, and beam imaging. Two-dimensional Cartesian particle-in-cell (PIC) simulations that qualitatively reproduce the experimental results suggest specific rapid heating of the thin targets by fast electrons, plasma expansion, and density decrease to relativistically transmissive conditions during the pulse.

Measurements of self-channeling of picosecond laser pulses due to relativistic and ponderomotive expulsion effects have been obtained in preformed plasmas at laser irradiances between 5–9×1018 Wcm−2. The self-focused channel was surrounded by a multi-megagauss magnetic field. The orientation of the field was consistent with a forward going relativistic electron beam propagating along the laser pulse. Self-channeling and magnetic field generation mechanisms were modeled by multidimensional particle-in-cell (PIC) simulations and good agreement was obtained with the experimental observations. Measurements of the channel expansion after the interaction were obtained and the rate of expansion was consistent with a blast wave solution. The level of transmission of an intense laser pulse through such performed density channels was observed to increase significantly compared to the case without a channel. High levels of transmission of an intense laser pulse through microtubes were also observed. The relevance of...

Neutron emission as high as ${10}^{7}$ is observed when a high intensity (a few ${10}^{19}\mathrm{W}/{\mathrm{cm}}^{2}$) subpicosecond laser pulse at 529 nm wavelength is focused on a deuterated polyethylene target. Neutron emission is also measured in different directions. The emission of neutrons along the laser axis is higher than in the transverse direction. Nonisotropic emission is consistent with neutrons generated by $\mathrm{D}(d,n){\ensuremath{-}}^{3}\mathrm{He}$ reaction for 0.3--1 MeV deuterons accelerated in the direction of the laser beam. The energy transferred to the ions is roughly estimated and compared with the energy carried out by the electrons.

The formation and evolution of density channels created by the interaction of a short bright (600 fs, $5\ifmmode\times\else\texttimes\fi{}{10}^{18}\mathrm{W}{\mathrm{cm}}^{\ensuremath{-}2}\ensuremath{\mu}{\mathrm{m}}^{2}$) laser pulse with a preformed plasma are studied by means of experiments and 2D particle-in-cell (PIC) simulations. Hollow density channels are observed by interferometry, and a fast radial expansion $(5\ifmmode\times\else\texttimes\fi{}{10}^{8}\mathrm{cm}/\mathrm{s})$ is measured. Magnetic fields around 50 MG inferred from Faraday rotation measurements suggest the occurrence of self-focusing. The PIC simulations support this hypothesis and show ion depletion during the laser pulse as well as radial expansion in agreement with experiments.

Relativistic electrons are produced, with energies up to 20MeV, by the interaction of a high-intensity subpicosecond laser pulse (1 {mu}m , 300 fs , 10{sup 19} W/cm{sup 2} ) with an underdense plasma. Two suprathermal electron populations appear with temperatures of 1 and 3MeV. In the same conditions, the laser beam transmission is increased up to 20{percent}{endash}30{percent}. We observe both features along with the evidence of laser pulse channeling. A fluid model predicts a strong self-focusing of the pulse. Acceleration in the enhanced laser field seems the most likely mechanism leading to the second electron population. {copyright} {ital 1997} {ital The American Physical Society}

Free electrons have been accelerated in vacuum to MeV energies by a high-intensity subpicosecond laser pulse (10{sup 19}W/cm{sup 2}, 300fs). The experimental data are in good agreement with the relativistic motion of electrons in a spatially and temporally finite electromagnetic field, both in terms of maximum energy and scattering angle. {copyright} {ital 1997} {ital The American Physical Society}

A multi-Petawatt high-energy laser PETAL coupled to the Ligne d’Int´ Laser (LIL) is under construction in the Aquitaine Region in France. This Petawatt laser will be dedicated to academic experiments in the fields of high energy density physics and ultra high intensity. Nd : glass laser chain coupled with the chirped pulse amplification (CPA technique allows delivery of high energy. Optical parametric CPA for pre-amplification and a new compression scheme will be implemented. PETAL is designed to deliver 3.6 kJ of energy in 500 fs on a target corresponding to 7.2 PW. The PETAL beam linked to the up to 60 kJ ns UV beams from the LIL will present new scientific research opportunities. (Some figures in this article are in colour only in the electronic version)

Calibrated thermoluminescence dosimeters have been used to measure the angular and spectral dependence of hard x‐ray emission produced from intense subpicosecond laser irradiation of solid targets. A dosimeter detector set with nine filter channels (13.5–400 keV) has been tested successfully. Total bremsstrahlung conversion up to 0.23% and conversion of 8×10−5 from laser energy to Ta Kα line emission (photon energy ≊57 keV) was determined. The scaling of the hard x‐ray yield with laser intensities ranging from 3×1016 to 3×1018 W/cm2 was investigated.

The experimental images of the sidescattered light from a plasma, created by the multiterawatt laser pulse propagating in a hydrogen gas jet, exhibit clear dependence on both gas jet pressure and laser power. Two‐ and three‐dimensional simulations of wave propagation, in presence of the relativistic electron mass increase and the ponderomotive expel of electrons, have been performed to reproduce the Thomson radiation from the plasma electrons. They show electron cavitation induced by the beam focusing, self‐focusing, self‐guiding, smoothing of the beam nonuniformities and, at larger power, beam filamentation. A bremsstrahlung model with account of the ionization, heating, expansion, and recombination dynamics of the gas, provides the plasma emission background. Both Thomson emission and bremsstrahlung are required to recover the experimental emission patterns. Among the interpretations, a scenario of laser self‐guiding over five Rayleigh lengths can be found for 10 TW laser power and 5×1018 cm−3 electron density, which surprisingly disappears at larger powers and densities.

The first experiments on the National Ignition Facility (NIF) in the US started and will be followed by the Laser MegaJoule (LMJ) in France. Such facilities will provide unique tools for inertial confinement fusion (ICF) physics & for basic science. A petawatt short pulse laser (ps) is being added to the ns pulse beams of the LMJ. This is PETAL (PETawatt Aquitaine Laser), under construction on the LMJ site near Bordeaux (France). The Petal+ project is aiming at the design and construction of diagnostics dedicated to experiments with PETAL and LMJ laser beams. Within Petal+, three types of diagnostics are under study: a proton spectrometer, an electron spectrometer and a large-band X-ray spectrometer. The first goal of these diagnostics will be to characterize the secondary radiation and particle sources produced with PETAL. They will also be used for experiments using both ns and ps beams. In the present paper emphasis is put on the charged-particle diagnostics.

The laser Megajoule (LMJ) facility is designed to provide the experimental capabilities to study High Energy Density Physics (HEDP). The LMJ is part of the Simulation Program, which combines improvement of physics models, high performance numerical simulation, and experimental validation. Since the operational commissioning of the LMJ, in October 2014, several experimental campaigns have been achieved. They have demonstrated the good performances of LMJ and demonstrated its aptitudes to perform experiments for the Simulation Program. The PETAL project consists in the addition of one short-pulse (ps) ultra- high-power, high-energy beam (kJ) to the LMJ facility. The first high energy test shots in the compressor stage of PETAL, performed in May 2015, have reached a power of 1.2 PW. PETAL will offer a combination of a very high intensity multi-petawatt beam, synchronized with the nanosecond beams of the LMJ. This combination will expand the LMJ experimental field in HEDP. LMJ-PETAL is open to the academic communities; the first experiments are planned in 2017.

The laser Megajoule (LMJ), developed by the French Commissariat a l'Energie Atomique et aux Energies Alternatives (CEA), will be a cornerstone of the French Simulation Program, which combines improvement of physics models, high performance numerical simulation, and experimental validation. The LMJ facility is under construction at CEA CESTA near Bordeaux and will provide the experimental capabilities to study High-Energy Density Physics (HEDP). One of its goals is to obtain ignition and burn of DT-filled capsules imploded, through indirect drive scheme, inside rugby-shape hohlraum. The PETAL project consists in the addition of one short-pulse (ps) ultra-high-power, high-energy beam (kJ) to the LMJ facility. PETAL will offer a combination of a very high intensity multi-petawatt beam, synchronized with the nanosecond beams of the LMJ. This combination will expand the LMJ experimental field on HEDP. This paper presents an update of LMJ & PETAL status, together with the development of the overall program including targets, plasma diagnostics and simulation tools.

Oral condition could be associated with cognitive impairment, but this is not yet well documented. We therefore hypothesized that people with poor oral condition would be more at risk to develop dementia. The objective of this study thus was to describe the oral condition of French community-dwelling elderly persons and to assess its relationship with the occurrence of dementia.Oral examination was conducted on a sample of individuals aged 66-80 years followed-up prospectively for screening of dementia over 15 years in Gironde, France. Univariate and multivariate analyses of the risk of dementia were performed using a Cox proportional hazard model with delayed entry.Data from 405 individuals were analyzed; 45.4% men; median age at baseline: 70 years [interquartile range (IQR): 68-75]. The median number of decayed, missing, and filled teeth was 18 (IQR: 13-24) and was higher in women (median: 20 versus 17, P = 0.004) and in persons with lower school level (median: 21 versus 17, P = 0.003). Among 348 persons with sextant eligible for periodontal assessment, 2/3 required periodontal care: 5.2% had bleeding observed, 44.8% calculus, 17.8% 4-5 mm pockets, and 2.9%≥ 6 mm pockets. The incidence of dementia during a median follow-up of 10 years (IQR: 6.5-13.7) was 19 per 1000 person-years. The adjusted hazard ratio for a number of missing teeth ≥ 11 (median) on the risk of dementia was 1.13 (95% confidence interval, CI = [0.60-2.12]) in people with higher education (n = 312) and 0.30 (CI = 0.11-0.79) in persons with lower school level (n = 93) (P for modification effect = 0.0002).Having eleven or more missing teeth seemed to be associated with a lower risk of dementia in people with lower education possibly owing to the suppression of source of chronic inflammation.

Demonstrating ignition and net energy gain in the near future on MJ-class laser facilities will be a major step towards determining the feasibility of Inertial Fusion Energy (IFE), in Europe as in the United States. The current status of the French Laser MégaJoule (LMJ) programme, from the laser facility construction to the indirectly driven central ignition target design, is presented, as well as validating experimental campaigns, conducted, as part of this programme, on various laser facilities. However, the viability of the IFE approach strongly depends on our ability to address the salient questions related to efficiency of the target design and laser driver performances. In the overall framework of the European HiPER project, two alternative schemes both relying on decoupling target compression and fuel heating—fast ignition (FI) and shock ignition (SI)—are currently considered. After a brief presentation of the HiPER project's objectives, FI and SI target designs are discussed. Theoretical analysis and 2D simulations will help to understand the unresolved key issues of the two schemes. Finally, the on-going European experimental effort to demonstrate their viability on currently operated laser facilities is described.

Two diagnostics for the study of hard x‐ray emission produced by plasmas during inertial confinement fusion experiments, are described: (i) a hard x‐ray spectrometer to measure the high‐energy tail of the spectrum, with eight spectral bands in the 50–400‐keV range, by fluorescence and simple filter techniques; (ii) a time‐integrated pinhole imaging device using a microchannel plate converter tube and a 7.5‐μm‐thick tantalum photocathode adjusted for a mean spectral sensitivity around 200 keV. Adjustment and test of these diagnostics have been performed with a pulsed hard x‐ray generator using a plasma focus device. Absolute calibration of the spectrometer detectors (scintillator Photomultiplier) was obtained on an x‐ray tube with fluorescent emission lines (10–100 keV) and with a cobalt radioactive source at 1.23 MeV.

Magic angle spinning, high power decoupling, dipolar dephasing are useful techniques to provide information from solid materials. Through a selection of examples (silicas, calcium phosphate bioceramics and carbonaceous materials) these methods are shown to give essential information for the understanding of these materials.

The purpose of this study was to assess the oral health status among a population of students enrolled in the first year at the Paul Sabatier University in Toulouse (France), and to compare the results with those of similar investigations.An epidemiologic survey of 1,500 students at the Centre for Preventive Medicine at Paul Sabatier University (UPS) will enable us to obtain the prevalence of certain variables such as DMFT, sugar consumption, tooth-brushing frequency, and mouthwash use, through a structured questionnaire and a standardised oral health examination.The Decayed, Missing and Filled Teeth (DMFT) index of these students was 4.4 (Standard Deviation = 3.72) (D = 1, M = 0.042 F = 3,454). Of the 1500 subjects, 27.6% smoke, while 43% eat sweets on a regular basis. The female students are more careful with their dental health (tooth-brushing frequency and mouthwash use are statistically significant (p0.001).Although the result of the DMFT index is lower in comparison to similar previous studies, a decrease in dental caries seems certain. The multifactorial knowledge of the caries aetiology motivates us to search for new, more sensitive indexes.

Acquired or congenital loss of structure can cause facial deformity. This can destroy identity and lead to certain forms of exclusion. Surgical and sometimes prosthetic reconstruction is required. The Maxillofacial Prosthesis (P.M.F) can be defined as the art and science of artificial reconstruction of facial bones. There is a continual increase in patient demand for this type of prosthesis with the development of new materials, methodologies and techniques.In Toulouse, the Rangueil University Hospital houses a maxillofacial prosthesis consultation facility linked to the Odontology Service. An exhaustive descriptive study carried out retrospectively on the basis of the files of all patients examined between July 1996 and July 2002 will provide us with an understanding of patient characteristics and also enable us to quantify the level of satisfaction of requirements for rehabilitation of these losses of maxillofacial structure.215 patient files were processed between July 1996 and July 2002. Separating the patients by sex shows a male prevalence of 66%. An analysis of variations between male and female patients for different aetiologies shows that tumour pathologies are more common in men and that this distinction is all the more marked as regards traumatic facial injuries and in particular suicide attempts. In total, 401 maxillofacial prostheses were carried out, including 116 facial epitheses (new prostheses or renewal of prosthesis).Loss of facial structure, whatever its aetiology constitutes a real public health issue. The maxillofacial prosthesis will allow cancer monitoring of the site while at the same time offering out patient treatment. Above and beyond its crafted or empirical aspect, it should find its place in medicine thanks to the overall scope of the rehabilitation that it can offer from both an aesthetic point of view but also a the psychological one, but above all from a functional perspective.

This work concerns a retrospective study of prevalence records and the clinical characteristics of localised aggressive periodontitis in the breast of consultants in the periodontitis service in Dental Medicine Faculty of Rabat (Morocco) from 1997 to 1999.

There are many ways of identifying victims of catastrophes but in disasters where most soft tissue has been lost, the hard tissues of teeth can be used. This article describes the important role that forensic odontology can play in these cases. This role has not been recognised in most countries, particularly developing countries, where forensic odontology has been restricted to legal affairs.

Location of the apical foramen using an electronic apex locator to determine working length is more accurate than using radiographs alone. The Neosono Co-pilote is not adversely affected by the presence of sodium hypochlorite and gives us acceptable results in dry canals. Hence, it is today possible to realize endodontic treatment without X ray determination.

The aim of this study was to evaluate the importance of the dental aesthetic for the patients, the dental surgeon and the dental teachers by the study of the consultation reason, the complaints, the post-university congress program, the practical program of the dental students and the programs of the IADR congress. It appears that in odontology, patients ask strongly for aesthetic care, in consultation and litigation. The content of congress and professional literature shows that dental surgeons answer to that request. Only the practical teaching was a bit less but it was recently modify. The research workers are also very interesting for aesthetic care.

A student, future decision-maker, has to measure the consequences of his indecision. In this study, a model of work with doubt is tested. We observe that the indecision is correlate with knowledge. His taking into consideration from continuous assessments allows us to predict his academic standard.

International audience; Neanderthal dental remains were discovered in the cave at Rochelot (Charente, France) which is known to have been inhabited by hyenas. Two left teeth, PMI and PM2 presented subvertical grooves located on their antagonist interproximal facets. Macroscopic and microscopic examination revealed that each vertical groove of an interproximal facet resembled its antagonist groove. Bibliographical research and our experiments on modern teeth have led us to develop a chonological classification of the elements leading to the ante mortern formation of these subvertical grooves.; Des restes dentaires néandertaliens ont été mis au jour dans la grotte de Rochelot (Charente, France) reconnue comme un repaire d'hyènes. Deux dents, PM1 et PM2 gauches, présentent des sillons subverticaux sur leurs facettes d'attrition interproximales et antagonistes. L'étude macroscopique et microscopique (MEB) révèle que chaque sillon d'une facette interproximale présente une concordance d'orientation et de dimensions avec son antagoniste. L'analyse bibliographique et notre expérimentation sur des dents actuelles nous conduisent à l'élaboration d'une classification chronologique des phénomènes aboutissant la formation ante mortem de ces sillons subverticaux.

The paper describes the preparation of the short-pulse high-energy laser PETawatt Aquitaine Laser (PETAL), which will be coupled to the Laser Megajoule (LMJ) laser of CEA. The LMJ/PETAL facility will be opened for the academic access of European researchers. In parallel, diagnostics are being developed within the PETAL + project and many physical problems are being addressed ranging from the study of the problems of radiation generation and activation issues to the problem of generation of large electromagnetic pulses.

In hearing the masking consists to disturb the information perception which means its reception, codeage and transmission are distorted in the auditory system. The electrophysiological technique by auditory evoked potentials on brain has permitted to study the noise effects with homolateral and contralateral masking method in monaural hearing. The results show that the noise distorts the maximal amplitude of the evoked response and lengthens latency. They do to appear a better resistance of a left ear preference and a superiority of right hemisphere corresponding: they characterize by an important development of auditory evoked potentials with or without masking. As a result for men who are exposed to excessive noise like teachers and students in Odontology, we suggest an inequality protection of auditory system considering the both ear sensibility difference.

The objective of this study is to describe the teeth decay affect of Moroccan children. The works of reference regroup a sample of 3004 children from 6 to 15 years old. The results are the next: the teeth decay concern 3 children for 5, the DMFT is 2 (bad) and 2 children for 3 have cariogenic dental plaque which means a bad bucco-dental hygiene and a great risk of decay recurrence. One child for two hasn't a toothbrush that increases the bad bucco-dental status. It appears that there is a cause-response relationship between the rate of decay the rate of cariogenic dental plaque and missing bucco-dental hygiene and also exaggerated consumption of sugar-refineries.

In order to extend plasma accelerators, the laser beam has to be guided inside gas or plasma over a distance of the order of the dephasing length, which is typically much larger than the diffraction length z/sub R/ of the laser. A capillary tube can be used as a waveguide for high-intensity laser pulses over distances well in excess of z/sub R/. Experimental demonstration of monomode guiding over 100 z/sub R/ of 10/sup 16/ W/cm/sup 2/ pulses has been obtained in evacuated capillary tubes (45-70-/spl mu/m inner diameter). A drop of transmission has been observed when the intensity of the amplified spontaneous emission (ASE) is high enough to ionize the capillary tube entrance. Propagation in helium gas-filled (10-40 mbar) capillary tubes has been studied at intensities up to 10/sup 16/ W/cm/sup 2/; a plasma column with on-axis density of the order of 10/sup 17/ cm/sup -3/ has been created on a length of the order of 4 cm. The use of a capillary tube for an extended accelerator is discussed for the ease of linear, resonant excitation of plasma waves by laser wakefield.

We present new progress in the optimization and understanding of the transient collisional pumping scheme using an ultra-short sub-ps heating pulse. The effect of traveling-wave irradiation in enhancing the lasing output of the 4d-4p Ni-like Ag line is studied in detail. A new irradiation scheme using a frequency-doubled 600 ps pulse to preform a plasma is tested. Strong lasing is also obtained on a new line at 16.05 nm that we identify to a 4f-4d transition in Ni-like Ag. Finally we review our recent work in the development of applications of the 21.2 nm zinc laser for imaging or exciting matter. New experiments include the probing of a plasma by imaging Fresnel interferometry and a first attempts to demonstrate two-photon ionization in a xenon gas.

Recent experiments, performed at the C.E.A./Limeil-Valenton P102 laser facility on the Ni-like transient collisional scheme, are reported in this paper. They mainly aimed at enhancing the efficiency and improving the optical properties of the already demonstrated 4d J equals 0/4p J equals 1 Ag 19+ x-ray laser at 13.9 nm. The now classical 2- stage traveling-wave irradiation of slab targets was used, the illumination sequence being constituted of a long (600 ps) low-flux (0.5 - 11 J) laser pulse followed (200 ps later) by a short (< 1 ps) high intensity (1 - 20 J) one. The work novelty was the use of frequency-doubled pulses, either for the pre-forming or the pumping one. Various combinations ((omega) -(omega) , 2(omega) -(omega) , (omega) - 2(omega) ) have been investigated in terms of lasing performances. High gains, around 34/cm, have been measured and saturation achieved for target lengths above 4 mm. A strong enhancement, up to a few (mu) J, of the x-ray laser output has been observed, due to traveling-wave irradiation method, while the emission duration was decreased to less than 10 ps, resulting in a 300 kW source. Moreover, under specific laser conditions, a second lasing line at 16 nm was detected. Finally, the possibility of cavity operating transient collisional x-ray lasers has been demonstrated.

Ultra-high intensity femtosecond laser pulses have been used to irradiate foil targets to study the concept of isochoric heating of dense matter. The ionization dynamics and electron density evolution of Al targets (thickness between 500 A and 2 μm) irradiated at laser intensity between 1018 W/cm2 and 1020 W/cm2, were inferred from time-resolved keV x-ray spectroscopy with 750fs resolution.

The numerical optimization of the temporal shape of the pump laser for the design of a 38.8 angstrom H-like x-ray laser is presented. Enhancement of local and integrated gains is obtained by smoothing the pulse rise, without drastic increase of the x-ray emission duration. Sensitivity of the results to the pulse intensity is also examined. High temporal resolution spectroscopy of aluminum targets performed in the keV range at the P102 facility in Limeil is finally presented.

We present and discuss time resolved spectra (KeV range) of solid density plasmas produced by the interaction of clean high intensity laser pulses (400 fs, 0.53 im light) with solid and foil targets at intensities between 1018 W/cm2 and 1020 W/cm2. Results have been obtained with the new PX1 x-ray streak camera which hasa temporal resolution of 750 fs in the KeV x-ray range.Keywords: X-ray Spectroscopy, Femtosecond temporal resolution, High density plasmas, Ultrashort laser producedplasmas. 1. INTRODUCTION Over the past seven years, a revolution has occurred in our ability to produce extremely compact, highaverage power and high intensity lasers. These recent progresses are the direct results of the use of both a newamplification technique, namely the technique of Chirped Pulse Amplification (CPA)[1}, and new broadbandamplification media such as Ti:sapphire and Cr:LiSAF[2]. Laser pulse lengths are now compressed down todurations of less than 100 femtosecond. Although the laser energy is not so high, large intensity can be achieved dueto extremely short pulse duration and very good focusability. Furthermore extremely high repetition rates are nowcurrently achieved[3}. These advances have made possible the production and the study ofhot solid density plasmaswhich are unique sources of ultrafast x-ray pulses[4,5]. These short pulses of x-rays could be a very useful tool to

First measurements of relativistic electrons produced by the interaction between a 400-fs, 1.06- $\ensuremath{\mu}\mathrm{m}$ ultrahigh-intensity laser pulse $(Ig{10}^{19}\mathrm{W}/{\mathrm{cm}}^{2})$ and a solid target are presented. For electrons ejected along the laser propagation axis in the forward direction, the relation of the hot temperature ${T}_{h}$ versus the laser intensity $I$ is found to be in very good agreement with a $\mathbf{J}\ifmmode\times\else\texttimes\fi{}\mathbf{B}$ ponderomotive model described by S. C. Wilks et al. [Phys. Rev. Lett. 69, 1383 (1992)], where ${T}_{h}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}({\ensuremath{\gamma}}_{\mathrm{osc}}\ensuremath{-}1){\mathrm{mc}}^{2}$. Hot temperature of transverse electrons scales as ${T}_{h}\ensuremath{\sim}{I}^{1/3}$.

The use of different shifted narrow band amplifying media in the chirped pulse amplification technique allows us to produce sub-100 TW pulses with duration in the 250 - 300 fs range. By focusing these pulses on target we have obtained peak intensities above 2.1019 W/cm2.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.