In vivo and in vitro ketamine exposure exhibits a dose-dependent induction of activity-dependent neuroprotective protein in rat neurons.

Anesthetic doses of ketamine induce apoptosis, as well as gene expression of activity-dependent neuroprotective protein (ADNP), a putative homeodomain transcription factor in rat pups (P7). This study investigated if ketamine induced ADNP protein in a dose-dependent manner in vitro and in vivo using primary cultures of cortical neurons and neonatal pups (P7). In vivo immunohistochemistry demonstrated a sub-anesthetic dose of ketamine increased ADNP in the somatosensory cortex (SCC) which was previously identified to be damaged by repeated exposure to anesthetic doses of ketamine. Administration of low-dose ketamine prior to full sedation prevented caspase-3 activation in the hippocampus and SCC. Primary cultures of cortical neurons treated with ketamine (10 µM-10mM) at 3 days-in vitro (3 DIV) displayed a concentration-dependent decrease in expanded growth cones. Furthermore, neuronal production and localization of ADNP varied as a function of both ketamine concentration and length of exposure. Taken together, these data support the model that ADNP induction may be partially responsible for the efficacy of a low-dose ketamine pre-treatment in preventing ketamine-induced neuronal cell death.

A compact proton spectrometer for measurement of the absolute DD proton spectrum from which yield and ρR are determined in thin-shell inertial-confinement-fusion implosions.

A compact, step range filter proton spectrometer has been developed for the measurement of the absolute DD proton spectrum, from which yield and areal density (ρR) are inferred for deuterium-filled thin-shell inertial confinement fusion implosions. This spectrometer, which is based on tantalum step-range filters, is sensitive to protons in the energy range 1-9 MeV and can be used to measure proton spectra at mean energies of ∼1-3 MeV. It has been developed and implemented using a linear accelerator and applied to experiments at the OMEGA laser facility and the National Ignition Facility (NIF). Modeling of the proton slowing in the filters is necessary to construct the spectrum, and the yield and energy uncertainties are ±<10% in yield and ±120 keV, respectively. This spectrometer can be used for in situ calibration of DD-neutron yield diagnostics at the NIF.

Empirical assessment of the detection efficiency of CR-39 at high proton fluence and a compact, proton detector for high-fluence applications.

CR-39 solid-state nuclear track detectors are widely used in physics and in many inertial confinement fusion (ICF) experiments, and under ideal conditions these detectors have 100% detection efficiency for ∼0.5-8 MeV protons. When the fluence of incident particles becomes too high, overlap of particle tracks leads to under-counting at typical processing conditions (5 h etch in 6N NaOH at 80 °C). Short etch times required to avoid overlap can cause under-counting as well, as tracks are not fully developed. Experiments have determined the minimum etch times for 100% detection of 1.7-4.3-MeV protons and established that for 2.4-MeV protons, relevant for detection of DD protons, the maximum fluence that can be detected using normal processing techniques is ≲3 × 10(6) cm(-2). A CR-39-based proton detector has been developed to mitigate issues related to high particle fluences on ICF facilities. Using a pinhole and scattering foil several mm in front of the CR-39, proton fluences at the CR-39 are reduced by more than a factor of ∼50, increasing the operating yield upper limit by a comparable amount.

National Ignition Facility neutron time-of-flight measurements (invited).

The first 3 of 18 neutron time-of-flight (nTOF) channels have been installed at the National Ignition Facility (NIF). The role of these detectors includes yield, temperature, and bang time measurements. This article focuses on nTOF data analysis and quality of results obtained for the first set of experiments to use all 192 NIF beams. Targets produced up to 2×10(10) 2.45 MeV neutrons for initial testing of the nTOF detectors. Differences in neutron scattering at the OMEGA laser facility where the detectors were calibrated and at NIF result in different response functions at the two facilities. Monte Carlo modeling shows this difference. The nTOF performance on these early experiments indicates that the nTOF system with its full complement of detectors should perform well in future measurements of yield, temperature, and bang time.

Experimental comparison of a Shack-Hartmann sensor and a phase-shifting interferometer for large-optics metrology applications.

We performed a direct side-by-side comparison of a Shack-Hartmann wave-front sensor and a phase-shifting interferometer for the purpose of characterizing large optics. An expansion telescope of our own design allowed us to measure the surface figure of a 400-mm-square mirror with both instruments simultaneously. The Shack-Hartmann sensor produced data that closely matched the interferometer data over spatial scales appropriate for the lenslet spacing, and much of the <20-nm rms systematic difference between the two measurements was due to diffraction artifacts that were present in the interferometer data but not in the Shack-Hartmann sensor data. The results suggest that Shack-Hartmann sensors could replace phase-shifting interferometers for many applications, with particular advantages for large-optic metrology.