Rapid heating of a compressed fusion fuel by a short-duration laser pulse is a promising route to generating energy by nuclear fusion, and has been demonstrated on an experimental scale using a novel fast-ignitor geometry. Here we describe a refinement of this system in which a much more powerful, pulsed petawatt (10(15) watts) laser creates a fast-heated core plasma that is scalable to full-scale ignition, significantly increasing the number of fusion events while still maintaining high heating efficiency at these substantially higher laser energies. Our findings bring us a step closer to realizing the production of relatively inexpensive, full-scale fast-ignition laser facilities.

e Genotypic HIV drug resistance testing is routinely used to guide clinical decisions. While genotyping methods can be standardized, a slow, labor-intensive, and subjective manual sequence interpretation step is required. We therefore performed external validation of our custom software RECall, a fully automated sequence analysis pipeline. HIV-1 drug resistance genotyping was performed on 981 clinical samples at the Stanford Diagnostic Virology Laboratory. Sequencing trace files were first interpreted manually by a laboratory technician and subsequently reanalyzed by RECall, without intervention. The relative performances of the two methods were assessed by determination of the concordance of nucleotide base calls, identification of key resistanceassociated substitutions, and HIV drug resistance susceptibility scoring by the Stanford Sierra algorithm. RECall is freely available at http://pssm.cfenet.ubc.ca. In total, 875 of 981 sequences were analyzed by both human and RECall interpretation. RECall analysis required minimal hands-on time and resulted in a 25-fold improvement in processing speed (ϳ150 technician-hours versus ϳ6 computation-hours). Excellent concordance was obtained between human and automated RECall interpretation (99.7% agreement for >1,000,000 bases compared). Nearly all discordances (99.4%) were due to nucleotide mixtures being called by one method but not the other. Similarly, 98.6% of key antiretroviral resistance-associated mutations observed were identified by both methods, resulting in 98.5% concordance of resistance susceptibility interpretations. This automated sequence analysis tool provides both standardization of analysis and a significant improvement in data workflow. The time-consuming, error-prone, and dreadfully boring manual sequence analysis step is replaced with a fully automated system without compromising the accuracy of reported HIV drug resistance data.

We present a supercritical radiative shock experiment performed with the LULI nanosecond laser facility. Using targets filled with xenon gas at low pressure, the propagation of a strong shock with a radiative precursor is evidenced. The main measured shock quantities (electronic density and propagation velocity) are shown to be in good agreement with theory and numerical simulations.

This research project examined the incidence, experience, salient features, and management of sexual attraction between psychologists and clients and assessed 908 American Psychological Association member psychologists who work in university counseling centers (43% return rate). Only 12% reported never having been attracted to any client, and 96% never had acted out sexually against a client. Almost half reported that their feelings of attraction benefited the therapy process, and 43% reported negative consequences. Sixty percent sought consultation or supervision to discuss this attraction. The results of this study support the need for increased awareness and education in this It is well documented that therapist-client sexual intimacy results in damaging, painful client experiences (

We report on shadowgraphic measurements showing the first space-and time-resolved snapshots of ultraintense laser pulse-generated fast electrons propagating through a solid target. A remarkable result is the formation of highly collimated jets (,20-mm) traveling at the velocity of light and extending up to 1 mm. This feature clearly indicates a magnetically assisted regime of electron transport, of critical interest for the fast ignitor scheme. Along with these jets, we detect a slower (ഠc͞2) and broader (up to 1 mm) ionization front consistent with collisional hot electron energy transport. 52.60. + h The fast ignitor scheme, which claims to relax some of the constraints hampering the standard approaches to inertial confinement fusion, has triggered a worldwide interest since its inception [1]. It hinges on the rapid additional heating of the core of a precompressed thermonuclear pellet due to the slowing down of a bunch of relativistic electrons generated by an ultraintense laser pulse. Now, the highly overcritical plasma surrounding the core should prevent any laser pulse from reaching it, whatever highintensity penetration mechanisms are at work (relativistic self-induced transparency [2] or ponderomotive hole boring [3]). An encouraging point is that particle-in-cell simulations predict a rather peaked hot electron distribution in the vicinity of the laser-solid interaction zone [4]. However, an efficient heating of the core requires the electron beam to remain collimated up to its final absorption zone, i.e., on a distance of several hundreds of microns. This can be achieved only through the pinching effect of the beam-driven magnetic field competing with multiple scattering. Therefore, fast electron transport from moderately to extremely dense regions appears as a key issue for the success of fast ignition, which must be thoroughly tackled both experimentally and theoretically.Over the past year, there has been a growing body of experimental evidence pointing to the existence of very collimated high intensity laser-produced electron jets traveling through solid targets. Tatarakis et al. have recently observed a narrow expanding plasma at the rear surface of thick plastic slabs irradiated by a 1 ps, 10 19 W͞cm 2 laser pulse [5]. By using a 2D Fokker-Planck hybrid code, they interpreted this localized rear heating as a magnetic field-enhanced electron energy deposition at the target/vacuum interface [6]. This effect has also been detected in other experiments [7]. Though very encouraging, these studies still provide an incomplete experimental picture of the phenomena arising in the bulk of the target.In the present paper, we report on optical shadowgraphic results showing what is, to our knowledge, the first comprehensive set of space-and time-resolved snapshots of fast electrons propagating through a solid target. In order to bypass the classical limitation of optical probing into an overcritical solid target, we use transparent glass slides. Our measurements pinpoint the existence of two types of fast...

In the last few years, high power lasers have demonstrated the possibility to explore a new state of matter, the so-called warm dense matter. Among the possible techniques utilized to generate this state, we present the dynamic compression technique using high power lasers. Applications to planetary cores material (iron) will be discussed. Finally new diagnostics such as proton and hard-x-ray radiography of a shock propagating in a solid target will be presented.

Electron transport within solid targets, irradiated by a high-intensity short-pulse laser, has been measured by imaging K(alpha) radiation from high- Z layers (Cu, Ti) buried in low- Z (CH, Al) foils. Although the laser spot is approximately 10 microm [full width at half maximum (FWHM)], the electron beam spreads to > or =70 microm FWHM within <20 microm of penetration into an Al target then, at depths >100 microm, diverges with a 40 degree spreading angle. Monte Carlo and analytic models are compared to our data. We find that a Monte Carlo model with a heuristic model for the electron injection gives a reasonable fit with our data.

We report on rear-side optical self-emission results from ultraintense laser pulse interactions with solid targets. A prompt emission associated with a narrow electron jet has been observed up to aluminum target thicknesses of 400 microm with a typical spreading half-angle of 17 degrees. The quantitative results on the emitted energy are consistent with models where the optical emission is due to transition radiation of electrons reaching the back surface of the target or due to a synchrotron-type radiation of electrons pulled back to the target. These models associated with transport simulation results give an indication of a temperature of a few hundred keV for the fast-electron population.