Effects of Laser Bandwidth in Direct-Drive High-Performance DT-Layered Implosions on the OMEGA Laser.

In direct-drive inertial confinement fusion, the laser bandwidth reduces the laser imprinting seed of hydrodynamic instabilities. The impact of varying bandwidth on the performance of direct-drive DT-layered implosions was studied in targets with different hydrodynamic stability properties. The stability was controlled by changing the shell adiabat from (α_{F}≃5) (more stable) to (α_{F}≃3.5) (less stable). These experiments show that the performance of lower adiabat implosions improves considerably as the bandwidth is raised indicating that further bandwidth increases, beyond the current capabilities of OMEGA, would be greatly beneficial. These results suggest that the future generation of ultra-broadband lasers could enable achieving high convergence and possibly high gains in direct drive ICF.

Impact of the boundary's sharpness on temporal reflection in dispersive media.

We investigate the impact of the finite rise time of a spatiotemporal boundary inside a dispersive medium used for reflection and refraction of optical pulses. We develop a matrix approach in the frequency domain for analyzing such spatiotemporal boundaries and use it to show that the frequency range over which reflection can occur is reduced as the rise time increases. We also show that total internal reflection can occur even for boundaries with long rise times. This feature suggests that spatiotemporal waveguides can be realized through cross-phase modulation even when pump pulses have relatively long rise and fall times.

Power balancing the multibeam OMEGA laser.

Multibeam lasers often require an output beam balance that specifies the degree of simultaneity of the laser output energy, instantaneous power, or instantaneous irradiance (power per unit area). This work describes the general problem of balancing a multibeam laser. Specific techniques used to balance the output power of the 60-beam pulsed OMEGA Laser System are discussed along with a measured reduction of beam-to-beam imbalance. In particular, the square-pulse distortion induced by a simple saturating amplifier operating with its output at some fraction of its saturation fluence is derived, and a method to exchange gain between saturated amplifiers in a single beam that have different saturation fluences to adjust balance is described.

What is the Temporal Analog of Reflection and Refraction of Optical Beams?

It is shown numerically and analytically that when an optical pulse approaches a moving temporal boundary across which the refractive index changes, it undergoes a temporal equivalent of reflection and refraction of optical beams at a spatial boundary. The main difference is that the role of angles is played by changes in the frequency. The frequency dependence of the dispersion of the material in which the pulse is propagating plays a fundamental role in determining the frequency shifts experienced by the reflected and refracted pulses. Our analytic expressions for these frequency shifts allow us to find the condition under which an analog of total internal reflection may occur at the temporal boundary.

Tackling the problem of blood culture contamination in the intensive care unit using an educational intervention.

Blood culture contamination (BCC) has been associated with unnecessary antibiotic use, additional laboratory tests and increased length of hospital stay thus incurring significant extra hospital costs. We set out to assess the impact of a staff educational intervention programme on decreasing intensive care unit (ICU) BCC rates to <3% (American Society for Microbiology standard). BCC rates during the pre-intervention period (January 2006-May 2011) were compared with the intervention period (June 2011-December 2012) using run chart and regression analysis. Monthly ICU BCC rates during the intervention period were reduced to a mean of 3.7%, compared to 9.5% during the baseline period (P < 0.001) with an estimated potential annual cost savings of about £250,100. The approach used was simple in design, flexible in delivery and efficient in outcomes, and may encourage its translation into clinical practice in different healthcare settings.

Inferred UV fluence focal-spot profiles from soft x-ray pinhole-camera measurements on OMEGA.

A method was developed with laser-irradiated Au planar foils to characterize the focal spot of UV laser beams on a target at full energy from soft x-ray emission. A pinhole camera with a back-thinned charge-coupled device detector and filtration with thin Be and Al foil filters provides images of the x-ray emission at photon energies <2 keV. This method requires a careful measurement of the relationship between the applied UV fluence and the x-ray signal, which can be described by a power-law dependence. The measured exponent γ ∼ 2 provides a dynamic range of ∼25 for the inferred UV fluence. UV fluence profiles of selected beams were measured for 100-ps and 1-ns laser pulses and were compared to directly measured profiles from an UV equivalent-target-plane diagnostic. The inferred spot size and super-Gaussian order from the x-ray technique agree within several percent with the values measured with the direct UV measurements.

A picosecond beam-timing system for the OMEGA laser.

A timing system is demonstrated for the OMEGA Laser System that guarantees all 60 beams will arrive on target simultaneously with a root mean square variability of 4 ps. The system relies on placing a scattering sphere at the target position to couple the ultraviolet light from each beam into a single photodetector.

Paternal and maternal major histocompatibility complex class I antigens are expressed co-dominantly by equine trophoblast.

Invasive equine trophoblast cells of the chorionic girdle express high levels of paternally inherited Major Histocompatibility Complex (MHC) class I antigens prior to migration into the endometrium to form the so-called endometrial cups. Three groups of experiments were performed to determine if maternally inherited MHC class I antigens are expressed on chorionic girdle cells. Results indicated that maternally and paternally inherited MHC class I antigens are co-dominantly expressed by cells of the invasive equine trophoblast, and therefore, that the expression of polymorphic equine MHC class I genes does not appear to be affected by genomic imprinting in this tissue. The demonstration that cells of the chorionic girdle were immunogenic supports the hypothesis that invasion of the maternal endometrium by chorionic girdle cells stimulates the production of anti-paternal alloantibodies normally observed in early horse pregnancy. The co-dominant expression of MHC class I antigens by invasive chorionic girdle cells has important implications for the mechanism of recognition of allogeneic fetal MHC class I antigens by the maternal immune system.

Measuring recognition memory.

Recent years have seen an expanded interest in recognition memory tasks. This resurgence of interest has also renewed concerns with measurement problems. Comparing 4 models of recognition memory, Snodgrass and Corwin (1988) found that measures of bias from the distribution-free (nonparametric) model were inadequate. However, their analysis was based on bias measures that can be shown a priori to be nonindependent of discrimination. This article traces the history of the nonparametric model and develops a better measure of bias. The consequence of developing this better measure is that the nonparametric model deserves serious consideration.

Biotin effects on fatty acid synthesis in chicks.

Data are summarized from several papers on the effects of biotin deficiency on lipid metabolism, especially fatty acid synthesis, in chicks. Biotin deficiency inhibits in vivo lipogenesis and hepatic acetyl-CoA carboxylase (ACC) activity. Although acetate incorporation into fatty acids is inhibited in biotin-deficient chicks, malonate incorporation is not inhibited. In fact, dietary malonic acid stimulates lipogenesis during biotin deficiency as measured by total carcass fatty acid content. Biotin-deficient chicks exhibit altered hepatic and whole body fatty acid composition in comparison with control chicks. The deficiency results in an increased proportion of the 16-carbon to 18-carbon fatty acids, and the most striking increase is for palmitoleic (16:1) acid. Biotin deficiency increases the relative incorporation of palmitate and stearate into phospholipids and decreases the relative incorporation of these fatty acids into triglycerides. Finally, mercury stimulates lipogenesis in biotin-deficient, but not in control, chicks by an unknown mechanism.

Selenium inhibition of avian fatty acid synthetase complex.

Injection of 0.48 or 0.72 mg of selenium/100 g body weight (as Na2SeO3) into 3-week-old chicks depressed hepatic activity of fatty acid synthetase compared with saline-injected controls. In in vitro experiments with fatty acid synthetase purified to homogeneity, Na2SeO3 was a competitive inhibitor (Ki = ca. 70 micronM). Dithiothreitol (DTT) at low concentrations increased the inhibition of the enzyme by Na2SeO3. At higher DTT concentrations the potentiating effect of DTT on selenium inhibition of the enzyme disappeared. At still higher DTT concentrations, selenium inhibition of fatty acid synthetase was partically relieved. If DTT and Na2SeO3 (2 : 1 molar ratio, respectively) in inhibitory concentrations, were reacted together prior to addition to enzyme and substrate, no inhibition was observed. Potentiation of selenium inhibition of fatty acid synthetase was observed with 2-mercaptoethanol but not with ascorbate. Several organic seleno-compounds were not inhibitory. The data suggest that selenium inhibits fatty acid synthetase by reversible bonding to the sulfhydryl (SH) groups (possibly at the active sites for acetyl-CoA and/or malonyl-CoA binding) of the enzyme. Selenotrisulfide formation involving selenium and the SH groups from the enzyme and thiol compounds is advanced as a possible explanation for the interaction among Se, DTT and enzyme observed in these experiments.

Mercury inhibition of avian fatty acid synthetase complex.

(1) Subcutaneous or intra-abdominal injections of 8 mg of HgCl2/100 g body weight markedly depressed hepatic fatty acid synthetase activity of chicks at 1 h post-injection. The depression occurred despite the fact that the chicks continued to eat up until the time they were killed. Under these same conditions, the hepatic activity of acetyl-CoA carboxylase (EC 6.4.1.2) was not affected by HgCl2, while the activity of the mitochondrial system of fatty acid elongation was stimulated. (2) When 2-mercaptoethanol was included in the incubation medium for a highly purified preparation of fatty acid synthetase, 500 muM HgCl2 was required to show definite inhibition of the enzyme. When 2-mercaptoethanol was omitted, 50 muM HgCl2 was inhibitory and 100 muM HgCl2 abolished enzyme activity. (3) 2 mM dithiothreitol completely protected the purified fatty acid synthetase preparation from inhibition by 100 muM HgCl2. When dithiothreitol was added after the addition of enzyme to the mercury-containing medium, protection of the enzyme was not complete. (4) Dialysis of cytosol fractions from chicks injected with HgCl2 against 500 vol. of 0.2 M potassium phosphate buffer (pH 7.0) containing 1 mM EDTA and 10 mM dithiothreitol for 4 h at 4 degrees stimulated the fatty acid synthetase activity of the fractions. Dialysis of cytosol fractions from noninjected chicks under the same conditions was without effect on fatty acid synthetase activity. (5) These data support the hypothesis that the inhibitory effect of HgCl2 administered in vivo on hepatic fatty acid synthetase activity in chicks is mediated through the interaction of mercury with the sulfhydryl groups of the enzyme.

Mercury inhibition of fatty acid synthesis in chicks.

Male chicks were fed a commercial ration and were given drinking water which contained 0, 50, 100, 150, 200 or 300 mug of mercury/ml as mercuric chloride from hatching to 3 weeks of age. In one experiment, the mercuric chloride was administered by injection into the abdominal cavity rather than in the drinking water. At 3 weeks the chicks were killed, and the livers were removed and weighed. The activity of fatty acid synthetase in the 800 X gav supernatant fractions of the liver homogenates and in vivo incorporation of [14C]acetate into liver and carcass fatty acids and respiratory 14CO2 was determined as indicated. Administration of mercury at a treatment level of 300 mug/ml of drinking water depressed growth, feed and water consumption, liver weight, hepatic fatty acid synthetase activity, and in vivo incorporation of [14C]acetate into liver and carcass fatty acids, and increased the production of respiratory 14CO2 as compared with controls. In experiments in which graded doses of mercury were administered, body weights, liver weights, and feed and water intakes of the chicks receiving 0, 50 and 100 mug of mercury/ml of drinking water were similar to each other, but these parameters were severely depressed by 200 mug of mercury/ml of drinking water. Mercury caused a dose-related decrease of fatty acid synthetase activity. Incorporation of [14C]acetate into carcass fatty acid was depressed by 50 and 200 mug of mercury/ml of drinking water; incorporation into liver fatty acids and production of respiratory 14CO2 was not affected by mercury. Intra-abdominal injection of 6 mg of mercury/100 g body weight (as mercuric chloride) into well alimented chicks depressed hepatic fatty acid synthetase activity at 1 h post-injection. The data are consistent with the hypothesis that a portion of the effects of mercury on fatty acid synthesis are direct rather than a secondary effect of inanition.

Preliminary experience with a method of quadricepsplasty in recurrent subluxation of the patella.

Nineteen knees were treated for recurrent subluxation or dislocation of the patella by lateral and distal transfer of the vastus medialis with or without release of the lateral retinaculum. Fifty-eight per cent has good or excellent and 42 per cent had poor results after a mean follow-up of twenty-nine months. The factors that predisposed to failure were genu valgum greater than 15 degrees and, to a lesser extent, palpable synovitis associated with symptomatic chondromalacia patellae.

Extraspinal causes of lumbosacral radiculopathy.

Twelve of 12,125 patients who had been referred during a seven-year period to a specialist in spinal disorders were found to have an extraspinal cause of radiculopathy or neuropathy of the lower extremity. The records of these twelve patients were reviewed retrospectively. The average age of the twelve patients was sixty-five years (range, forty-two to seventy-seven years). The cause of the symptoms was an occult malignant tumor in nine patients and a hematoma, an aneurysm of the obturator artery, or a neurilemoma of the sciatic nerve in the others. The average time from the onset of symptoms to the final diagnosis was eight months (range, one month to two years). The most useful test for determination of the correct diagnosis was computed tomography or magnetic resonance imaging of the abdomen and pelvis. Computed tomography or magnetic resonance imaging of the spine and bone-scanning of the whole body were of little help in localizing the disease. In four of the twelve patients, an operation was performed on the basis of an incorrect diagnosis. In dealing with elderly patients who have radiculopathy, one should be suspicious that the cause is outside the spine.

Effect of lead toxicity on the organ concentration of glutathione and glutathione-related free amino acids in the chick.

Total non-protein sulfhydryl (NPSH) and glutathione (GSH) concentrations in liver and kidney and GSH-related free amino acid concentrations in liver, kidney and plasma were examined in the chick following intoxication with 2000 ppm dietary lead (Pb). After 3 weeks, NPSH content was significantly (P less than 0.05) increased by Pb in both liver and kidney while only liver GSH was increased by Pb treatment. The concentrations of glutamate, glycine and methionine were elevated in liver by Pb while glycine, cysteine and cystathionine concentrations were increased in the kidney. In plasma, Pb significantly decreased cysteine, taurine and cystathionine concentrations.

An equine B cell surface antigen defined by a monoclonal antibody.

A surface antigen of equine B lymphocytes was identified using the Equine Leucocyte Antigen Workshop antibody WS 65. This marker was expressed on almost all equine B cells, but not on T cells, granulocytes or thymocytes. WS 65 strongly stained cells in the follicular areas of lymph nodes and cells in the splenic nodules when tested on frozen tissue sections by immunohistochemistry. Equine leukemic T cells were not labeled by WS 65, and neither were the cells from a horse with B cell leukemia, although these latter cells carried surface immunoglobulin. Immunoprecipitation of lymphocyte membrane molecules with the antibody produced a band at 85-90 kDa under reducing conditions. The equine B cell antigen defined by WS 65 appears to be different from surface immunoglobulin by its molecular characteristics and its lack of expression on malignant B cells.

A comparison of recollective memory and source monitoring.

Participants in recognition memory experiments are often asked for additional information about their memories after each positive recognition response. Two experiments were conducted that were identical, except that the first asked participants to make remember/familiar judgments about the items they recognized, and the second asked them to make source judgments. The similarity between the recollection and source judgment data has implications for measurement issues and theory development.

Symptomatic gas-containing disc herniation. Report of four cases.

Intradiscal gas collection, causing the radiographic vacuum phenomenon, is a common finding on radiographic studies of the lumbar spine. Four cases of radiographically documented and surgically confirmed cases of herniated discs containing gas are presented. All four patients presented with radicular symptoms secondary to the gas-containing herniations. Minimal nuclear material was found at surgery; however, all patients experienced relief after the operation.

Surgical treatment for the far lateral herniated lumbar disc.

Twenty-nine patients underwent surgery for far lateral herniated nucleus pulposus. Average patient age was 65 years in the 14 male and 15 female patients involved. The L4-5 disc was the most commonly herniated level (59%) followed by L3-4 (31%), L5-S1 (7%), and L2-3 (3%). All patients were initially seen with radiculopathy and 23 patients (79%) had motor weakness. A pars interarticularis sparing technique is described for approaching this type of disc herniation. This approach allows direct visualization of the disc and involved root. The results are encouraging with 72% of patients having good or excellent relief of pain. Seventy-one percent of those with preoperative weakness had no weakness or improvement in strength postoperatively. In general, far lateral herniated nucleus pulposus occurs in older patients and at high lumbar disc levels. Postoperative results are similar to the more common posterolateral herniated nucleus pulposus in patients of the same age group. A surgical approach is described to better address the less familiar anatomy.