High-Performance Indirect-Drive Cryogenic Implosions at High Adiabat on the National Ignition Facility.

To reach the pressures and densities required for ignition, it may be necessary to develop an approach to design that makes it easier for simulations to guide experiments. Here, we report on a new short-pulse inertial confinement fusion platform that is specifically designed to be more predictable. The platform has demonstrated 99%+0.5% laser coupling into the hohlraum, high implosion velocity (411 km/s), high hotspot pressure (220+60 Gbar), and high cold fuel areal density compression ratio (>400), while maintaining controlled implosion symmetry, providing a promising new physics platform to study ignition physics.

Longitudinal and Transverse Instability of Ion Acoustic Waves.

Ion acoustic waves are found to be susceptible to at least two distinct decay processes. Which process dominates depends on the parameters. In the cases examined, the decay channel where daughter modes propagate parallel to the mother mode is found to dominate at larger amplitudes, while the decay channel where the daughter modes propagate at angles to the mother mode dominates at smaller amplitudes. Both decay processes may occur simultaneously and with onset thresholds below those suggested by fluid theory, resulting in the eventual multidimensional collapse of the mother mode to a turbulent state.

Multibeam Stimulated Raman Scattering in Inertial Confinement Fusion Conditions.

Stimulated Raman scattering from multiple laser beams arranged in a cone sharing a common daughter wave is investigated for inertial confinement fusion (ICF) conditions in a inhomogeneous plasma. It is found that the shared electron plasma wave (EPW) process, where the lasers collectively drive the same EPW, can lead to an absolute instability when the electron density reaches a matching condition dependent on the cone angle of the laser beams. This mechanism could explain recent experimental observations of hot electrons at early times in ICF experiments, at densities well below quarter critical when two plasmon decay is not expected to occur.

Circular closure is associated with the lowest rate of surgical site infection following stoma reversal: a systematic review and multiple treatment meta-analysis.

AIM: Stoma reversal is frequently complicated by surgical site infection (SSI). To reduce SSI, several techniques for skin closure have been studied, with no agreement on which is best. The aim of this study was to identify the skin closure technique associated with the lowest rate of SSI following stoma reversal. METHOD: We systematically searched MEDLINE (PubMed and OvidSP), Scopus and clinical registries from 1 January 1980 to 24 March 2012, and included original reports on adult patients following stoma reversal. A network of treatments was created to map the comparisons between skin closure techniques, including primary closure, primary closure with a drain, secondary closure, delayed primary closure, loose primary closure and circular closure. Pairwise meta-analyses were performed for all available direct comparisons of closure types and heterogeneity was assessed. A multiple-treatments meta-analysis was conducted to estimate relative treatment effects between competing closure types (reported as an odds ratio with 95% credible interval, and a probability that each treatment is best). Several sensitivity analyses were performed. RESULTS: Fifteen studies were identified with a total of 2921 cases of stoma reversal. Overall, study quality was poor with observed low (one study), moderate (seven studies) and high (seven studies) risk of bias. Circular closure was associated with the lowest SSI risk (OR 0.12; 95% CI 0.02-0.40) and was the best of six skin closure techniques (probability of being best = 68.9%). Circular closure remained the best after sensitivity analyses. CONCLUSION: This study showed that circular closure is the best skin closure technique after stoma reversal in terms of SSI rate, but the quality of supporting evidence is limited, precluding definite conclusions.

Regional deposition of mometasone furoate nasal spray suspension in humans.

Nasal deposition studies can demonstrate whether nasal sprays treating allergic rhinitis and polyposis reach the ciliated posterior nasal cavity, where turbinate inflammation and other pathology occurs. However, quantifying nasal deposition is challenging, because in vitro tests do not correlate to human nasal deposition; gamma scintigraphy studies are thus used. For valid data, the radiolabel must distribute, as the drug, into different-sized droplets, remain associated with the drug in the formulation after administration, and not alter its deposition. Some nasal deposition studies have demonstrated this using homogenous solutions. However, most commercial nasal sprays are heterogeneous suspensions. Using mometasone furoate nasal suspension (MFS), we developed a technique to validate radiolabel deposition as a surrogate for nasal cavity drug deposition and characterized regional deposition and nasal clearance in humans. Mometasone furoate (MF) formulation was spiked with diethylene triamine pentacaetic acid. Both unlabeled and radiolabeled formulations (n = 3) were sprayed into a regionally divided nasal cast. Drug deposition was quantified by high pressure liquid chromatography within each region; radiolabel deposition was determined by gamma camera. Healthy subjects (n = 12) were dosed and imaged for six hours. Scintigraphic images were coregistered with magnetic resonance imaging scans to quantify anterior and posterior nasal cavity deposition and mucociliary clearance. The ratio of radiolabel to unlabeled drug was 1.05 in the nasal cast and regionally appeared to match, indicating that in vivo radiolabel deposition could represent drug deposition. In humans, MFS delivered 86% (9.2) of metered dose to the nasal cavity, approximately 60% (9.1) of metered dose to the posterior nasal cavity. After 15 minutes, mucociliary clearance removed 59% of the initial radiolabel in the nasal cavity, consistent with clearance rates from the ciliated posterior surface. MFS deposited significant drug into the posterior nasal cavity. Both nasal cast validation and mucociliary clearance confirm the radiolabel deposition distribution method accurately represented corticosteroid nasal deposition.

Kinetic theory and Vlasov simulation of nonlinear ion-acoustic waves in multi-ion species plasmas.

The theory of damping and nonlinear frequency shifts from particles resonant with ion-acoustic waves (IAWs) is presented for multi-ion species plasma and compared to driven wave Vlasov simulations. Two distinct IAW modes may be supported in multi-ion species plasmas, broadly classified as fast and slow by their phase velocity relative to the constituent ion thermal velocities. In current fusion-relevant long pulse experiments, the ion to electron temperature ratio, T(i)/T(e), is expected to reach a level such that the least damped and thus more readily driven mode is the slow mode, with both linear and nonlinear properties that are shown to differ significantly from the fast mode. The lighter ion species of the slow mode is found to make no significant contribution to the IAW frequency shift despite typically being the dominant contributor to the Landau damping.

Kinetic simulations of the self-focusing and dissipation of finite-width electron plasma waves.

Two-dimensional simulations, both Vlasov and particle-in-cell, are presented that show the evolution of the field and electron distribution of finite-width, nonlinear electron plasma waves. The intrinsically intertwined effects of self-focusing and dissipation of field energy caused by electron trapping are studied in simulated systems that are hundreds of wavelengths long in the transverse direction but only one wavelength long and periodic in the propagation direction. From various initial wave states, both the width at focus Δm relative to the initial width Δ0 and the maximum field amplitude at focus are shown to be a function of the growth rate of the transverse modulational instability γTPMI divided by the loss rate of field energy νE to electrons escaping the trapping region. With dissipation included, an amplitude threshold for self-focusing γTPMI/νE∼1 is found that supports the analysis of Rose [Phys. Plasmas 12, 012318 (2005)].

Alpha heating of indirect-drive layered implosions on the National Ignition Facility.

In order to understand how close current layered implosions in indirect-drive inertial confinement fusion are to ignition, it is necessary to measure the level of alpha heating present. To this end, pairs of experiments were performed that consisted of a low-yield tritium-hydrogen-deuterium (THD) layered implosion and a high-yield deuterium-tritium (DT) layered implosion to validate experimentally current simulation-based methods of determining yield amplification. The THD capsules were designed to reduce simultaneously DT neutron yield (alpha heating) and maintain hydrodynamic similarity with the higher yield DT capsules. The ratio of the yields measured in these experiments then allowed the alpha heating level of the DT layered implosions to be determined. The level of alpha heating inferred is consistent with fits to simulations expressed in terms of experimentally measurable quantities and enables us to infer the level of alpha heating in recent high-performing implosions.

Stochastic ion heating from many overlapping laser beams in fusion plasmas.

In this Letter, we show through numerical simulations and analytical results that overlapping multiple (N) laser beams in plasmas can lead to strong stochastic ion heating from many (~N(2)) electrostatic perturbations driven by beat waves between pairs of laser beams. For conditions typical of inertial-confinement-fusion experiment conditions, hundreds of such beat waves are driven in mm(3)-scale plasmas, leading to ion heating rates of several keV/ns. This mechanism saturates cross-beam energy transfer, with a reduction of linear gains by a factor ~4-5 and can strongly modify the overall hydrodynamics evolution of such laser-plasma systems.

Demonstration of ignition radiation temperatures in indirect-drive inertial confinement fusion hohlraums.

We demonstrate the hohlraum radiation temperature and symmetry required for ignition-scale inertial confinement fusion capsule implosions. Cryogenic gas-filled hohlraums with 2.2 mm-diameter capsules are heated with unprecedented laser energies of 1.2 MJ delivered by 192 ultraviolet laser beams on the National Ignition Facility. Laser backscatter measurements show that these hohlraums absorb 87% to 91% of the incident laser power resulting in peak radiation temperatures of T(RAD)=300 eV and a symmetric implosion to a 100 µm diameter hot core.

Hotspot parameter scaling with velocity and yield for high-adiabat layered implosions at the National Ignition Facility.

This paper presents a study on hotspot parameters in indirect-drive, inertially confined fusion implosions as they proceed through the self-heating regime. The implosions with increasing nuclear yield reach the burning-plasma regime, hotspot ignition, and finally propagating burn and ignition. These implosions span a wide range of alpha heating from a yield amplification of 1.7-2.5. We show that the hotspot parameters are explicitly dependent on both yield and velocity and that by fitting to both of these quantities the hotspot parameters can be fit with a single power law in velocity. The yield scaling also enables the hotspot parameters extrapolation to higher yields. This is important as various degradation mechanisms can occur on a given implosion at fixed implosion velocity which can have a large impact on both yield and the hotspot parameters. The yield scaling also enables the experimental dependence of the hotspot parameters on yield amplification to be determined. The implosions reported have resulted in the highest yield (1.73×10^{16}±2.6%), yield amplification, pressure, and implosion velocity yet reported at the National Ignition Facility.

Calcium hydroxide: its role in the fracture of tricalcium silicate paste.

The large areas of crystalline calcium hydroxide [Ca(OH)(2)] formed during the hydration of tricalcium silicate (Ca(3)SiO(5)) correspond to low-porosity regions in the hydrated paste. During the early stage of hydration, areas between Ca(OH)(2) crystals which consist of Ca(3)SiO(5) particles bonded together by calcium silicate hydrate represent the high-porosity portion of the paste. Because of the presence of Ca(OH)(2), fracture in the hardened paste during this period propagates preferentially through the areas bonded by the calcium silicate hydrate phase and around the Ca(OH)(8), crystals. Calcium hydroxide also acts as a crack arrester. The influence of Ca(OH)(2) on fracture diminishes with increased hydration.

Physiological concentrations of lactate dehydrogenases and substrate inhibition.

Lactate dehydrogenases at physiological concentrations are inhibited by high concentrations of pyruvate when the enzyme and the pyruvate are incubated in the presence of oxidized nicotinamide-adenine dinucleotide before assay. The inhibition is much more pronounced with the H-type than with the M-type lactate dehydrogenase. These results suggest that substrate inhibition may be operative in vivo.

Collisional damping rates for electron plasma waves reassessed.

Collisional damping of electron plasma waves, the primary damping for high phase velocity waves, is proportional to the electron-ion collision rate, ν_{ei,th}. Here, it is shown that the damping rate normalized to ν_{ei,th} depends on the charge state, Z, on the magnitude of ν_{ei,th} and the wave number k in contrast with the commonly used damping rate in plasma wave research. Only for weak collision rates in low-Z plasmas for which the electron self-collision rate is comparable to the electron-ion collision rate is the damping rate given by the commonly accepted value. The result presented here corrects the result presented in textbooks at least as early as 1973. The complete linear theory requires the inclusion of both electron-ion pitch-angle and electron-electron scattering, which itself contains contributions to both pitch-angle scattering and thermalization.

Beyond the gain exponent: Effect of damping, scale length, and speckle length on stimulated scatter.

Three-dimensional wave propagation simulations and experiments show that the gain exponent, an often used metric to assess the likelihood of stimulated Brillouin scatter, is insufficient and must be augmented with another parameter, Nr, the ratio of the resonance length, Lres, to the laser speckle length. The damping rate of ion acoustic waves, ν, and thus Lres, which is proportional to ν, are easily varied with plasma species composition, e.g., by varying the ratio of hydrogen and carbon ions. As Nr decreases, stimulated Brillouin scattering increases despite the same gain exponent.

Dental nerve regeneration in rats. II. Autoradiographic studies of nerve regeneration to molar pulp and dentin.

The autoradiographic technique was used to analyze the degeneration and regeneration of sensory nerves to rat molars and gingiva following cut or crush injury to the right inferior alveolar nerve. At 2 days after nerve injury there was almost complete denervation of the first molar, partial denervation of the second molar, and minimal effect on the innervation to the third molar and gingiva. The degree of sensory deficit and recovery for these same rats had been previously determined. Reinnervation of the first molar was analyzed in terms of axon number and location, intensity of axon labeling, and type of nerve injury. At 6 days, neither the cut injury nor crush injury rats had any reinnervation of their first molars. By 7 days, 3 of 4 rats had axons reinnervating first molars; in those teeth there was approximately one-fourth of the normal number of axons in the pulp, and very few axons in the dentin. These rats still had as large a molar sensory deficit as the 7 day rat and 6 day rats that had no reinnervation. By 3 weeks there were one-half to three-fourths of the normal axon numbers in the pulp, one-fourth to one-half of the normal axon numbers in dentin; and sensitivity was at least half-recovered. By 6 weeks, numbers of axons in the pulp and dentin were either normal or slightly less than normal; axons had grown back into dentin to the same depth as in normal teeth; and complete recovery of sensitivity had occurred. The regenerating axons had greater than normal labeling intensity at 1 week and 3 weeks in all rats. Those with the crush nerve injury had somewhat greater numbers of reinnervating axons at 1 week and 3 weeks than the cut injury rats. A structure-function comparison for the molars showed that return of sensitivity correlated with reinnervation of both pulp and dentin.

Dental nerve regeneration in rats. I. Electrophysiological studies of molar sensory deficit and recovery.

Return of sensory nerve function in rat molars following cut or crush injury to the inferior alveolar nerve (IAN) was measured by observing the jaw opening reflex (JOR) response of the digastric muscle to electrical stimulation of individual molars or the gingiva. The IAN was injured from a lateral approach to the mandibular ramus at a site approximately 2 mm proximal to the incisor apex. Following nerve injury, the JOR threshold to stimulation of the first molars increased 6-fold: preoperative threshold mean = 47.4 +/- 21.3 microA (n = 27), postoperative threshold mean = 248.5 +/- 127.1 microA (n = 25). A 4-fold postoperative increase in JOR threshold was found for the second molars, and the thresholds were not significantly affected for third molars or gingiva. These postoperative results indicated that the major pathway of sensory innervation to the first and second molars was affected by the IAN injury, whereas the third molars and gingiva had alternate sources of innervation which remained unaffected by the IAN injury. At 1 week following injury, there was partial return of sensitivity, by 3 weeks there was approximately 50% recovery, and by 6 weeks complete return to normal JOR thresholds was found. The degree of sensory deficit, as reflected in JOR inhibition, and the rate of recovery were not significantly different after cut or crush injury in these experiments; however, there was a tendency for greater sensory loss and for more rapid recovery after crush injury. This study forms the basis for a subsequent autoradiographic analysis of nerve location in rat molars of known sensory deficit, partial recovery, or full sensory recovery.

Left ventricular false aneurysm after coronary bypass surgery: radionuclide diagnosis and surgical resection.

A patient with left ventricular pseudoaneurysm formation resulting from myocardial infarction 4 years after coronary bypass surgery is described. The pseudoaneurysm was diagnosed with gated cardiac blood pool imaging and was subsequently successfully surgically repaired. Postoperative pericardial abnormalities predisposing to the possible development of a false aneurysm are discussed. Also, clinical situations in which pseudoaneurysm should be suspected are described, and appropriate diagnostic approaches are outlined.

Effect of coronary bypass surgery on survival patterns in subsets of patients with left main coronary artery disease. Report of the Collaborative Study in Coronary Artery Surgery (CASS).

The 3 year cumulative survival rate of 1,492 patients with left main coronary artery disease (50 percent or greater stenosis of luminal diameter) enrolled in the Collaborative Study in Coronary Artery Surgery (CASS) was 91 percent for the surgical group and 69 percent for patients treated medically (p less than 0.0001). Mortality was significantly greater in patients with impaired left ventricular function. The difference between medical and surgical therapy was significant for patients who had normal, moderately abnormal and severely impaired left ventricular function and for patients with stenosis of the left main coronary artery of 50 to 59, 60 to 69, 70 to 79 and 80 percent or greater. Aortocoronary bypass surgery did not significantly improve survival in patient subgroups who had (1) a nonstenotic dominant right or balanced coronary circulation, (2) a stenotic dominant right coronary artery and normal left ventricular function, and (3) left main coronary stenosis of 50 to 59 percent and normal or mildly abnormal left ventricular function. The Cox proportional hazards model was used to select baseline variables that were independent predictors of long-time mortality. The model selected left ventricular score, age, congestive heart failure score, hypertension, percent left main coronary arterial stenosis and coronary arterial dominance as the baseline variables most predictive of long-term survival. A clinical and angiographic prognostic risk index developed from these six baseline variables showed significantly improved survival for the surgical cohort in each of four risk categories. In the best and worst risk category, the 3 year survival rate was 97 and 82 percent, respectively, for the surgical group and 85 and 34 percent, respectively, for the medical group (p less than or equal to 0.0002). The data from this observational study show that coronary bypass surgery prolongs life in most patients with left main coronary artery disease, particularly those who have severe narrowing of the left main coronary artery or impaired left ventricular function. The results permit a better understanding of the natural history of left main coronary artery disease and permit a more accurate estimate of long-term survival for individual patients through the use of a clinical-angiographic risk index.

Infection in remnant of left ventricular assist device after successful separation from assisted circulation.

There have been two long-term and two short-term survivors among 10 patients in our hospital in whom the left ventricular assist device (LVAD) was implanted for cardiogenic shock after cardiac operations. Two of these four patients developed graft infection in the LVAD remnants left attached to the ascending aorta and left ventricle; one died of sepsis and the other required repeat operations for a chronic draining sinus and hemorrhage from a left ventricular--cutaneous fistula. This experience with infection and demonstration of the feasibility of total removal of both limbs of the LVAD without cardiopulmonary bypass lead us to recommend complete removal of the LVAD conduits in patients weaned from assisted circulation.