Demonstration of Scale-Invariant Rayleigh-Taylor Instability Growth in Laser-Driven Cylindrical Implosion Experiments.

Rayleigh-Taylor instability growth is shown to be hydrodynamically scale invariant in convergent cylindrical implosions for targets that varied in radial dimension and implosion timescale by a factor of 3. The targets were driven directly by laser irradiation providing a short impulse, and instability growth at an embedded aluminum interface occurs as it converges radially inward by a factor of 2.25 and decelerates on a central foam core.

Physiologic Electrical Fields Direct Retinal Ganglion Cell Axon Growth In Vitro.

Purpose: The purpose of this study was to characterize the ability of applied electrical fields (EFs) to direct retinal ganglion cell (RGC) axon growth as well as to assess whether Rho GTPases play a role in translating electrical cues to directional cues.

Methods: Full-thickness, early postnatal mouse retina was cultured in electrotaxis chambers and exposed to EFs of varying strengths (50-200 mV/mm). The direction of RGC axon growth was quantified from time-lapsed videos.

Self-Similar Multimode Bubble-Front Evolution of the Ablative Rayleigh-Taylor Instability in Two and Three Dimensions.

The self-similar nonlinear evolution of the multimode ablative Rayleigh-Taylor instability (ARTI) is studied numerically in both two and three dimensions. It is shown that the nonlinear multimode bubble-front penetration follows the α_{b}A_{T}(∫sqrt[g]dt)^{2} scaling law with α_{b} dependent on the initial conditions and ablation velocity. The value of α_{b} is determined by the bubble competition theory, indicating that mass ablation reduces α_{b} with respect to the classical value for the same initial perturbation amplitude.

How high energy fluxes may affect Rayleigh-Taylor instability growth in young supernova remnants.

Energy-transport effects can alter the structure that develops as a supernova evolves into a supernova remnant. The Rayleigh-Taylor instability is thought to produce structure at the interface between the stellar ejecta and the circumstellar matter, based on simple models and hydrodynamic simulations. Here we report experimental results from the National Ignition Facility to explore how large energy fluxes, which are present in supernovae, affect this structure.

A Highly Sensitive Enzymatic Catalysis System for Trace Detection of Arsenic in Water.

Arsenic (As) is an extremely toxic element that exists in the environment in different chemical forms. The detection of arsenic in potable water remains a challenging task. This study presents a highly sensitive enzymatic catalysis system for trace sensing of inorganic arsenic in water.

Enhanced accuracy of x-ray spectra reconstruction from filtered diode array measurements by adding a time integrated spectrometer.

A new approach for the spectral reconstruction of time-dependent emission of soft x-ray sources based on the measurement of filtered x-ray diode array systems is suggested. Two reconstruction methods, based on this approach, are demonstrated using both simulated and measured data. The methods use the filtered x-ray diode measurement together with a co-aligned, time-integrated, spectrally resolved measurement, such as transmission grating spectroscopy.

Measurements of laser generated soft X-ray emission from irradiated gold foils.

Soft x-ray emission from laser irradiated gold foils was measured at the Omega-60 laser system using the Dante photodiode array. The foils were heated with 2 kJ, 6 ns laser pulses and foil thicknesses were varied between 0.5, 1.

Observation of Single-Mode, Kelvin-Helmholtz Instability in a Supersonic Flow.

We report the first observation, in a supersonic flow, of the evolution of the Kelvin-Helmholtz instability from a single-mode initial condition. To obtain these data, we used a novel experimental system to produce a steady shock wave of unprecedented duration in a laser-driven experiment. The shocked, flowing material creates a shear layer between two plasmas at high energy density.

[Determination of molecular glioblastoma subclasses on the basis of analysis of gene expression].

Two glioblastoma groups, which are distinguished from each other by expression level of 416 genes (P < 0.05), were determined using a mathematical model of linear Boolean programming on the basis of gene expression data, obtained by microarray analysis of the glioblastomas and available in Gene Expression Omnibus (GEO) data base. The expression level of 15 genes was more than two-fold higher in the first group of glioblastoma (80 samples) in comparison with the second group (144 samples) and 401 genes and--more than two-fold lower as compared to the second group.

Generalized measurable ignition criterion for inertial confinement fusion.

A multidimensional measurable criterion for central ignition of inertial-confinement-fusion capsules is derived. The criterion accounts for the effects of implosion nonuniformities and depends on three measurable parameters: the neutron-averaged total areal density (rhoR(n)(tot)), the ion temperature (T(n)), and the yield over clean (YOC=ratio of the measured neutron yield to the predicted one-dimensional yield). The YOC measures the implosion uniformity.

Rayleigh-Taylor growth measurements in the acceleration phase of spherical implosions on OMEGA.

The Rayleigh-Taylor (RT) growth of 3D broadband nonuniformities was measured using x-ray radiography in spherical plastic shells accelerated by laser light at an intensity of approximately 2 x 10(14) W/cm(2). The 20- and 24-microm-thick spherical shells were imploded with 54 beams on the OMEGA laser system. The shells contained diagnostic openings for backlighter x rays used to image shell modulations.

Validation of thermal-transport modeling with direct-drive, planar-foil acceleration experiments on OMEGA.

We present for the first time the experimental validation of the nonlocal thermal-transport model for a National Ignition Facility relevant laser intensity of approximately 10(15) W/cm(2) on OMEGA. The measured thin target trajectories are in good agreement with predictions based on the nonlocal model over the full range of laser intensities from 2 x 10(14) to 10(15) W/cm(2}) The standard local thermal-transport model with a constant flux limiter of 0.06 disagrees with experimental measurements at a high intensity of approximately 10(15) W/cm(2) but agrees at lower intensities.

Rayleigh-Taylor growth stabilization in direct-drive plastic targets at laser intensities of approximately 1 x 10(15) W/cm2.

Direct-drive, planar-target Rayleigh-Taylor growth experiments were performed for the first time to test fundamental physics in hydrocodes at peak drive intensities of ignition designs. The unstable modulation growth at a drive intensity of approximately 1 x 10(15) W/cm2 was strongly stabilized compared to the growth at an intensity of approximately 5 x 10(14) W/cm2. The experiments demonstrate that standard simulations based on a local model of electron thermal transport break down at peak intensities of ignition designs (although they work well at lower intensities).

Monoenergetic-proton-radiography measurements of implosion dynamics in direct-drive inertial-confinement fusion.

Time-gated, monoenergetic radiography with 15-MeV protons provides unique measurements of implosion dynamics in direct-drive inertial-confinement fusion. Images obtained during acceleration, coasting, deceleration, and stagnation display a comprehensive picture of spherical implosions. Critical information inferred from such images, hitherto unavailable, characterizes the spatial structure and temporal evolution of self-generated fields and plasma areal density.

High-areal-density fuel assembly in direct-drive cryogenic implosions.

The first observation of ignition-relevant areal-density deuterium from implosions of capsules with cryogenic fuel layers at ignition-relevant adiabats is reported. The experiments were performed on the 60-beam, 30-kJUV OMEGA Laser System [T. R.

Role of hot-electron preheating in the compression of direct-drive imploding targets with cryogenic D2 ablators.

The compression of direct-drive, spherical implosions is studied using cryogenic D2 targets on the 60-beam, 351-nm OMEGA laser with intensities ranging from approximately 3x10(14) to approximately 1x10(15) W/cm2. The hard-x-ray signal from hot electrons generated by laser-plasma instabilities increases with laser intensity, while the areal density decreases. Mitigating hot-electron production, by reducing the laser intensity to approximately 3x10(14) W/cm2, results in areal density of the order of approximately 140 mg/cm2, in good agreement with 1D simulations.

Studies of plastic-ablator compressibility for direct-drive inertial confinement fusion on OMEGA.

The compression of planar plastic targets was studied with x-ray radiography in the range of laser intensities of I approximately 0.5 to 1.5x10(15) W/cm2 using square (low-compression) and shaped (high-compression) pulses.

High-rhoR implosions for fast-ignition fuel assembly.

Thick, 40 microm plastic shells filled with 25-35 atm of D2 or D3He were imploded on a low-adiabat (alpha approximately 1.3) and with a low-implosion velocity ( approximately 2 x 10(70 cm/s) on the OMEGA laser to generate massive cores of compressed plasma with high areal densities optimal for fast ignition. The targets are driven by 20-kJ relaxation adiabat-shaping laser pulses to keep the inner portion of the shell nearly Fermi degenerate.

p300 and p53 levels determine activation of HIF-1 downstream targets in invasive breast cancer.

In previous studies, we noted that overexpression of hypoxia-inducible factor (HIF)-1alpha in breast cancer, especially the diffuse form, does not always lead to functional activation of its downstream genes. Transcriptional activity of HIF-1 may be repressed by p53 through competition for transcriptional coactivators such as p300. The aim of this study was therefore to explore the role of p53 and p300 in relation to overexpression of HIF-1alpha and activation of HIF-1 downstream genes in invasive breast cancer.

Shock-wave mach-reflection slip-stream instability: a secondary small-scale turbulent mixing phenomenon.

Theoretical and experimental research, on the previously unresolved instability occurring along the slip stream of a shock-wave Mach reflection, is presented. Growth rates of the large-scale Kelvin-Helmholtz shear flow instability are used to model the evolution of the slip-stream instability in ideal gas, thus indicating secondary small-scale growth of the Kelvin-Helmholtz instability as the cause for the slip-stream thickening. The model is validated through experiments measuring the instability growth rates for a range of Mach numbers and reflection wedge angles.

Self-assembled electrical circuits and their electronic properties.

A straightforward method for the self assembly of single walled carbon nanotubes (SWNTs) between gold electrodes was developed. The technique utilizes the hybridization between short complementary DNA sequences located on metal contacts and SWNTs. new technique enables simple production of hundreds of devices with high yields.

Observation of self-similar behavior of the 3D, nonlinear Rayleigh-Taylor instability.

The Rayleigh-Taylor unstable growth of laser-seeded, 3D broadband perturbations was experimentally measured in the laser-accelerated, planar plastic foils. The first experimental observation showing the self-similar behavior of the bubble size and amplitude distributions under ablative conditions is presented. In the nonlinear regime, the modulation sigma(rms) grows as alpha(sigma)gt(2), where g is the foil acceleration, t is the time, and alpha(sigma) is constant.

High initial amplitude and high Mach number effects on the evolution of the single-mode Richtmyer-Meshkov instability.

Effects of high-Mach numbers and high initial amplitudes on the evolution of the single-mode Richtmyer-Meshkov shock-wave induced hydrodynamic instability are studied using theoretical models, experiments, and numerical simulations. Two regimes in which there is a significant deviation from the linear dependence of the initial velocity on the initial perturbation amplitude are defined and characterized. In one, the observed reduction of the initial velocity is primarily due to large initial amplitudes.

Synthesis and characterization of a new tetradentate ligand for Cu(II) metal ions.

The synthesis and characterization of a tailor-made ligand 1 is described. Self-assembly of 1 on a GaAs surface was studied by FT-IR spectroscopy. The IR spectrum of the thin film points to the conclusion that the monolayer adsorbs to the surface via both carboxylates of the malonic acid derivative.

Direct detection of low-concentration NO in physiological solutions by a new GaAs-based sensor.

Nitric oxide (NO) acts as a signal molecule in the nervous system, as a defense against infections, as a regulator of blood pressure, and as a gate keeper of blood flow to different organs. In vivo, it is thought to have a lifetime of a few seconds. Therefore, its direct detection at low concentrations is difficult.