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.

Influence of a random phase plate on the growth of the backward stimulated Brillouin scatter.

We derive the analytical dispersion relation of a high-energy laser beam's backward stimulated Brillouin scattering (BSBS) in a hot plasma, that accounts both for the random phase plate (RPP) induced spatial shaping and its associated phase randomness. Indeed, phase plates are mandatory in large laser facilities where a precise control of the focal spot size is required. While the focal spot size is well controlled, such techniques produce small scale intensity variations that can trigger laser-plasma instabilities such as BSBS. Quantifying the resulting instability variability is shown to be crucial for understanding accurately the backscattering temporal and spatial growth as well as the asymptotic reflectivity. Our model, validated by means of a large number of three-dimensional paraxial simulations and experimental data, offers three quantitative predictions. The first one addresses the temporal exponential growth of the reflectivity by deriving and solving the BSBS RPP dispersion relation. A large statistical variability of the temporal growth rate is shown to be directly related to the phase plate randomness. Then, we predict the portion of the beam's section that is absolutely unstable, thus helping to precisely assess the validity of the vastly used convective analysis. Finally, a simple analytical correction to the plane wave spatial gain is extracted from our theory giving a practical and effective asymptotic reflectivity prediction that includes the impact of phase plates smoothing techniques. Hence, our study sheds light on the long-time studied BSBS, deleterious to many high-energy experimental studies related to the physics of inertial confinement fusion.

Interpretation of proton radiography experiments of hohlraums with three-dimensional simulations.

Proton radiography experiments of laser-irradiated hohlraums performed at the OMEGA laser facility are analyzed using three-dimensional (3D) hydrodynamic simulations coupled to a proton trajectography package. Experiments with three different laser irradiation patterns were performed, and each produced a distinct proton image. By comparing these results with synthetic proton images obtained by sending protons through plasma profiles in the hohlraum obtained from 3D radiation hydrodynamic simulations, it is found that the simulated images agree favorably with the experimental images when electric fields, due to the electron pressure gradients that arise from 3D structures occurring during plasma expansion, are included. These comparisons provide quantitative estimates of the electric field present inside the hohlraums.

Spondylolysis in the past: A case study of hunter-gatherers from Southern Patagonia.

Spondylolysis is a fracture of the pars interarticularis, the portion of the neural arch that lies between the superior articular facets and the inferior articular facets. Clinical evidence has suggested repetitive trauma to be the most probable cause, even though morphological weakness of the vertebra is probably also involved. Prevalence is between 3% and 8% in modern populations, while in archaeological samples it varies from 0% to 71.4%. Considering that very little data about this condition is available in past populations from the southern extreme of South America, the aim of this paper is to analyze the spondylolysis in a human skeletal sample from Southern Patagonia and, at the same time, to explore the prevalence of spondylolysis in archaeological contexts around the world to gain a better understanding of the results presented here. The Southern Patagonian skeletal series analyzed here showed a prevalence of 20%, with lower prevalence in the pre contact sample (11.1%) than in the contact period (23.1%). Skeletons from the Salesian Mission "Nuestra Señora de La Candelaria" showed a higher prevalence (25%) than the sample of skeletal remains recovered from outside the mission (20%), suggesting that changes in lifestyle of hunter-gatherers during contact could be implicated in the development of spondylolysis in this sample. A worldwide survey displays a wide range of prevalence figures in American and Asian samples and low diversity between African and European populations. Hunter-gatherers from Southern Patagonia showed similar values to those observed in other American samples.

Experimental Investigation of the Collective Raman Scattering of Multiple Laser Beams in Inhomogeneous Plasmas.

Experiments have been performed evidencing significant stimulated Raman sidescattering (SRS) at large angles from the density gradient. This was achieved in long scale-length high-temperature plasmas in which two beams couple to the same scattered electromagnetic wave further demonstrating for the first time this multiple-beam collective SRS interaction. The collective nature of the coupling and the amplification at large angles from the density gradient increase the global SRS losses and produce light scattered in novel directions out of the planes of incidence of the beams. These findings obtained in plasmas conditions relevant of inertial confinement fusion experiments similarly apply to the more complex geometry of these experiments where anomalously large levels of SRS were measured.

Spatial and Transient Effects during the Amplification of a Picosecond Pulse Beam by a Nanosecond Pump.

Amplification of a picosecond pulse beam by a lower intensity nanosecond pulse beam was experimentally observed in a flowing plasma. Modifications of intensity distributions in beam focal spots due to nonhomogeneous energy transfer and its transient regime were investigated. The mean transferred power reached 57% of the incident power of the nanosecond pulse beam. An imaging diagnostic allowed the intensity profile of the picosecond pulse beam to be determined, bringing to evidence the spatial nonuniformity of energy transfer in the amplified beam. This diagnostic also enabled us to observe the temporal evolution of the speckle intensity distribution because of the transfer. These results are reproduced by numerical simulations of two complementary codes. The method and the observed effects are important for the understanding of experiments with multiple crossing laser beams in plasmas.

Experimental Evidence of the Collective Brillouin Scattering of Multiple Laser Beams Sharing Acoustic Waves.

The indirect-drive scheme to inertial confinement fusion uses a large number of laser beams arranged in a symmetric angular distribution. Collective laser plasma instabilities can therefore develop that couple all the incident laser waves located in a cone to the daughter wave growing along the cone symmetry axis [D. F. DuBois et al., Phys. Fluids B 4, 241 (1992)]. With complementary diagnostics of Thomson scattering and of the scattered light, we demonstrate the occurrence of collective stimulated Brillouin sidescattering driving collective acoustic waves in indirect-drive experiments.

Laser light triggers increased Raman amplification in the regime of nonlinear Landau damping.

Stimulated Raman backscattering (SRS) has many unwanted effects in megajoule-scale inertially confined fusion (ICF) plasmas. Moreover, attempts to harness SRS to amplify short laser pulses through backward Raman amplification have achieved limited success. In high-temperature fusion plasmas, SRS usually occurs in a kinetic regime where the nonlinear response of the Langmuir wave to the laser drive and its host of complicating factors make it difficult to predict the degree of amplification that can be achieved under given experimental conditions. Here we present experimental evidence of reduced Landau damping with increasing Langmuir wave amplitude and determine its effects on Raman amplification. The threshold for trapping effects to influence the amplification is shown to be very low. Above threshold, the complex SRS dynamics results in increased amplification factors, which partly explains previous ICF experiments. These insights could aid the development of more efficient backward Raman amplification schemes in this regime.

Driven spatially autoresonant stimulated Raman scattering in the kinetic regime.

The autoresonant behavior of Langmuir waves excited by stimulated Raman scattering (SRS) is clearly identified in particle-in-cell (PIC) simulations in an inhomogeneous plasma. As previously shown via a 3-wave coupling model [T. Chapman et al., Phys. Plasmas 17, 122317 (2010)], weakly kinetic effects such as trapping can be described via an amplitude-dependent frequency shift that compensates the dephasing of the resonance of SRS due to the inhomogeneity. The autoresonance (AR) leads to phase locking and to growth of the Langmuir wave beyond the spatial amplification expected from Rosenbluth's model in an inhomogeneous profile [M. N. Rosenbluth, Phys. Rev. Lett. 29, 565 (1972)]. Results from PIC simulations and from a 3-wave coupling code show very good agreement, leading to the conclusion that AR arises even beyond the so-called weakly kinetic regime.

Cancer genomics: promises and complexities.

The impending final deciphering of the complete human genome, coupled with the advancement of high-throughput technologies, is positioned to bring about a fundamental transformation in cancer research. The era of molecular biology is transforming into the era of genomic biology, with an unprecedented promise of understanding multifactorial diseases and of identifying specific targets that can be used to develop patient-tailored therapies. Although the genomic approach is in an early phase of its development and its tools need to be honed, the application of genomic technologies to cancer research has already generated exciting results both in target identification and in disease classification. In this article, we review some of the developments pertinent to cancer research, discuss potentially problematic areas associated with them, and comment on future trends and issues.

Burn patients' pain and anxiety experiences.

The purpose of this study was to examine burn patients' pain and anxiety experiences during resting conditions and procedures. The relationship of contextual factors and interventions to pain and anxiety were also explored. Procedural pain was significantly higher than resting pain (P = .02); however, there were no significant differences in anxiety between resting conditions and procedures (P = .16). There was a significant difference between burn patients' acceptable level of pain, resting pain, and procedural pain (P = .01). Resting pain was significantly lower than patients' acceptable level of pain (P = < .01). Procedural pain was slightly lower than patients' acceptable level of pain, but these results were not statistically significant (P = .37). Percent of total body surface burned was associated with increased procedural anxiety (P = .022). Family presence correlated with decreased procedural pain (P = .011) and midazolam use (P = .047). Prior experience with the procedure was associated with increased morphine(P = .003) and midazolam use (P = .029). These findings support the multifactorial nature of burn pain and anxiety and provide guidance for practice.

Cardiac anticholinergic effects of procainamide and its N-acetylated metabolite: experimental pharmacological and radioligand binding studies.

1. The cardiac anticholinergic effects of procainamide (1 mg kg(-1) min(-1)) and its N-acetylated metabolite (NAPA) at equimolar dose (1.16 mg kg(-1) min(-1)) were studied using in vivo experimental pharmacological and in vitro radioligand binding studies. 2. Procainamide and NAPA progressively reduced vagal stimulation-induced bradycardia in chloralose-anaesthetized dogs. As indicated by the ED50, the vagolytic activity of NAPA is 1.5-2.0 times weaker than that of procainamide. Both drugs increased heart rate, with lowering of mean blood pressure during the second part of procainamide infusion, but not during NAPA infusion. 3. Binding studies on rat heart membranes yielded Ki values that were 1.5 times higher for NAPA than for procainamide. 4. These results show that NAPA exerts a weaker cardiac vagolytic action than procainamide, which is probably linked to a lower ability to bind to cardiac muscarinic receptors.

Ontogenesis of LH and FSH receptors in postnatal rabbit testes: age-dependent differential expression of long and short RNA transcripts.

The ontogeny of testicular LH and FSH receptors was studied in New Zealand rabbits from 20 to 180 days postpartum. The concentrations of free receptors (per mg total proteins) were very low at day 20. They increased steeply at day 30 for the LH receptor and at day 50 for the FSH receptor. Three RNA bands (1.2, 2.5 and 3 kb) were repeatedly detected on northern blots for the LH receptor and two bands (1.2 and 2.2 kb) were detected for the FSH receptor. The 1.2 kb band (which cannot give rise to full-length, membrane-anchored receptor) was present throughout the 20-180 day period for each receptor. However, the higher molecular mass bands were nearly undetectable at day 20. The 2.5 and 3 kb bands of the LH receptor increased twofold between day 20 and day 120, while the 2.2 kb band of the FSH receptor increased fivefold between day 20 and day 75. Thus the very low concentrations, or even absence, of the larger transcripts of both LH and FSH receptors were correlated with the inability to detect their cognate protein until 20 days of age. Subsequently, coordinated increases in high molecular mass transcripts and protein were observed for both receptors. Total LH receptor content increased in parallel to the previously reported increase in plasma testosterone between day 65 and day 100. FSH receptor density began to increase steeply at day 50, just at the onset of spermatogenesis. Thus, postnatal testicular development in the rabbit seems to entail the transcription of high molecular mass, translatable transcripts of the gonadotrophin receptors.

Reperfusion injury and exhaled hydrogen peroxide.

Reactive oxygen species have been implicated in the pathophysiology of lung injury associated with the sequence of ischemia-reperfusion. To study this, we measured the exhaled breath hydrogen peroxide concentration [H2O2] in human and canine models of reperfusion lung injury. Our models were patients subjected to cardiopulmonary bypass (CPB) (Group 1), patients undergoing pulmonary thromboendarterectomy (Group 2), canine single lung transplant (Group 3), and patients subjected to peripheral ischemia resulting from aortic cross-clamping or tourniquet application (Group 4). In addition, we studied two groups with severe lung injury as positive controls. These consisted of hydrochloric acid (HCl)-induced canine lung injury (Group 5) and patients with adult respiratory distress syndrome (Group 6). The exhaled H2O2 was collected by using a -2 degrees C glass coil and assayed by a spectrophotometric method. In Group 1 samples were collected before and immediately after CPB. Group 2 samples were obtained before CPB, immediately after CPB, 3 h later, and daily until extubation. Samples in Group 3 were collected before lung transplant, and hourly for 3 h beginning immediately afterward. Group 4 samples were collected at the onset of reperfusion. Samples from Group 5 were collected before HCl and after HCl injury, at 0.5-1.5 and 2-3 h. Group 6 samples were collected when criteria for adult respiratory distress syndrome were met. Groups 1, 3, and 4 exhibited no significant increases in exhaled [H2O2] compared to control values. Group 2 had significantly increased [H2O2] (5.59 +/- 3.07 x 10(-7) mol/L, P = 0.028) on postoperative Day 2, but there was no correlation of [H2O2] with physiologic indicators of lung injury.(ABSTRACT TRUNCATED AT 250 WORDS)

General anesthesia and exhaled breath hydrogen peroxide.

To study the role of free radical formation on the impairment of pulmonary function seen with general anesthesia, we measured the hydrogen peroxide (H2O2) concentration in the exhaled breath condensate of 27 patients. Patients were divided into three study groups: a healthy patient group (group 1, n = 15) consisting of ASA physical status 1 and 2 patients undergoing elective noncardiothoracic surgery; a specific anesthetic event group (group 2, n = 6) composed of patients undergoing cardiopulmonary bypass (CPB); and a positive control group (group 3, n = 6) consisting of patients with the adult respiratory distress syndrome (ARDS). The exhaled breath condensate was collected by diverting exhaled breath through a glass condensation coil submerged in an ice/salt water bath. The exhaled breath condensate samples were then assayed using a spectrophotometric method. In group 1, samples were collected before and after the induction of general anesthesia with intravenous drugs, and before and after the administration of the inhalational anesthetics isoflurane (1.5%) (n = 7) or N2O (70%) (n = 8). In group 2, samples were collected pre- and post-CPB, and in group 3, when specific diagnostic criteria for ARDS were met. There was no significantly detectable H2O2 (not significantly different from zero) in any of the samples from the group 1 patients. Similarly, group 2 patients had exhaled breath H2O2 concentrations near zero except for one patient who was positive for the lupus anticoagulant. Group 3 patients had a mean (+/- SE) exhaled breath H2O2 concentration of 0.55 (+/- 0.08) microM, which was significantly greater than zero (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)