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The micrometer-scale tube that fills capsules with thermonuclear fuel in inertial confinement fusion experiments at the National Ignition Facility is also one of the implosion's main degradation sources. It seeds a perturbation that injects the ablator material into the center, radiating away some of the hot-spot energy. This paper discusses how the perturbation arises in experiments using high-density carbon ablators and how the ablator mix interacts once it enters the hot-spot. Both modeling and experiments show an in-flight areal-density perturbation and localized x-ray emission at stagnation from the fill-tube. Simulations suggest that the fill-tube is degrading an otherwise 1D implosion by ∼2×, but when other degradation sources are present, the yield reduction is closer to 20%. Characteristics of the fill-tube assembly, such as the through-hole size and the glue mass, alter the dynamics and magnitude of the degradation. These aspects point the way toward improvements in the design, some of which (smaller diameter fill-tube) have already shown improvements. [ABSTRACT FROM AUTHOR]

During the first few hundred picoseconds of indirect drive for inertial confinement fusion on the National Ignition Facility, x-ray spots formed on the hohlraum wall when the drive beams cast shadows of the fuel fill-tube on the capsule surface. Differential ablation at the shadow boundaries seeds perturbations which are hydrodynamically unstable under subsequent acceleration and can grow to impact capsule performance. We have characterized this shadow imprint mechanism and demonstrated two techniques to mitigate against it using (i) a reduced diameter fuel fill-tube, and (ii) a pre-pulse to blow down the fill-tube before the shadow forming x-ray spots from the main outer drive beams develop. [ABSTRACT FROM AUTHOR]

Hydrodynamic instability growth of capsule support membranes (or “tents”) has been recognized as one of the major contributors to the performance degradation in high-compression plastic capsule implosions at the National Ignition Facility (NIF) [E. M. Campbell et al., AIP Conf. Proc. 429, 3 (1998)]. The capsules were supported by tents because the nominal 10-μm diameter fill tubes were not strong enough to support capsules by themselves in indirect-drive implosions on NIF. After it was recognized that the tents had a significant impact of implosion's stability, new alternative support methods were investigated. While some of these methods completely eliminated tent, other concepts still used tents, but concentrated on mitigating their impact. The tent-less methods included “fishing pole” reinforced fill tubes, cantilevered fill tubes, and thin-wire “tetra cage” supports. In the “fishing pole” concept, a 10-μm fill tube was inserted inside 30-μm fill tube for extra support with the connection point located 300 μm away from the capsule surface. The cantilevered fill tubes were supported by 12-μm thick SiC rods, offset by up to 300 μm from the capsule surfaces. In the “tetra-cage” concept, 2.5-μm thick wires (carbon nanotube yarns) were used to support a capsule. Other concepts used “polar tents” and a “foam-shell” to mitigate the effects of the tents. The “polar tents” had significantly reduced contact area between the tents and the capsule compared to the nominal tents. In the “foam-shell” concept, a 200-μm thick, 30 mg/cc SiO2 foam layer was used to offset the tents away from the capsule surface in an attempt to mitigate their effects. These concepts were investigated in x-ray radiography experiments and compared with perturbations from standard tent support. The measured perturbations in the “fishing pole,” cantilevered fill tube, and “tetra-cage” concepts compared favorably with (were smaller than) nominal tent perturbations and were recommended for further testing for feasibility in layered DT implosions. The “polar tents” were tested in layered DT implosions with a relatively-stable “high-foot” drive showing an improvement in neutron yield in one experiment compared to companion implosions with nominal tents. This article reviews and summarizes recent experiments on these alternate capsule support concepts. In addition, the concept of magnetic levitation is also discussed. [ABSTRACT FROM AUTHOR]

Objective: Traffic incidents occurring on roadways require the coordinated effort of multiple responder and recovery entities, including communications, law enforcement, fire and rescue, emergency medical services, hazardous materials, transportation agencies, and towing and recovery. The objectives of this study were to (1) identify and characterize transportation incident management (TIM)-related occupational fatalities; (2) assess concordance of surveillance data sources in identifying TIM occupations, driver vs. pedestrian status, and occupational fatality incident location; and (3) determine and compare U.S. occupational fatality rates for TIM industries.Methods: The Kentucky Fatality Assessment and Control Evaluation (FACE) program analyzed 2005-2016 TIM occupational fatality data using multiple data sources: death certificate data, Collision Report Analysis for Safer Highways (CRASH) data, and media reports, among others. Literal text analysis was performed on FACE data, and a multiple linear regression model and SAS proc sgpanel were used to estimate and visualize the U.S. TIM occupational mortality trend lines and confidence bounds.Results: There were 29 TIM fatalities from 2005 to 2015 in Kentucky; 41% of decedents were in the police protection occupation, and 21% each were in the fire protection and motor vehicle towing industries. Over one half of the TIM decedents were performing work activities as pedestrians when they died. Media reports identified the majority of the occupational fatalities as TIM related (28 of 29 TIM-related deaths); the use of death certificates as the sole surveillance data source only identified 17 of the 29 deaths as TIM related, and the use of CRASH data only identified 4 of the 29 deaths as TIM related. Injury scenario text analysis showed that law enforcement vehicle pursuit, towing and recovery vehicle loading, and disabled vehicle response were particular high-risk activities that led to TIM deaths. Using U.S. data, the motor vehicle towing industry had a significantly higher risk for occupational mortality compared to the fire protection and police protection industries.Conclusions: Multiple data sources are needed to comprehensively identify TIM fatalities and to examine the circumstances surrounding TIM fatalities, because no one data source in itself was adequate and undercounted the total number of TIM fatalities. The motor vehicle towing industry, in particular, is at elevated risk for occupational mortality, and targeted mandatory TIM training for the motor vehicle towing industry should be considered. In addition, enhanced law enforcement roadside safety training during vehicle pursuit and apprehension of suspects is recommended. [ABSTRACT FROM AUTHOR]

We report a reduced X-ray shadow imprint of hydrodynamic instabilities on the high-density carbon ablator surface of inertial confinement fusion (ICF) capsules using a reduced diameter fuel fill tube on the National Ignition Facility (NIF). The perturbation seed mass from hydrodynamic instabilities was reduced by approximately an order of magnitude by reducing both the diameter and wall thickness of the fill tube by ∼2×, consistent with analytical estimates. This work demonstrates a successful mitigation strategy for engineered features for ICF implosions on the NIF. [ABSTRACT FROM AUTHOR]

Objective:Prescription drug overdoses, abuse, and sales have increased dramatically in the United States in the last decade. The purpose of the present study was to link crash data with emergency department (ED) and inpatient hospitalization data to assess the concordance between the data sets in the identification of the presence of drugs among injured motor vehicle drivers (passenger cars, passenger trucks, light trucks, and semi-trucks) in Kentucky. Methods:Kentucky CRASH data were probabilistically linked to ED data sets for years 2008–2010 and to inpatient hospitalization data sets for years 2000–2010. Statistical analyses were performed. Results:Of the 72,529 linked crash/ED visits, there were 473 drivers with an associated nondependent abuse of drugs diagnosis in the ED, and 930 drivers had drug involvement recorded in the CRASH data (only 163 cases overlapped with drug involvement both recorded in CRASH data and coded as nondependent abuse of drugs in the ED); 64 drivers had multiple drug types present in their system. Of the 20,860 total linked crash/inpatient hospitalization cases, there were 973 drivers diagnosed with nondependent abuse of drugs in the inpatient hospitalization record and 499 drivers had drug involvement recorded in the CRASH data (only 207 overlapped); 250 drivers were diagnosed with multiple drugs in their system. Conclusions:Surveillance data from multiple public health data sets is necessary to identify the presence of drugs in injured drivers involved in motor vehicle crashes. The use of a single surveillance data set alone may significantly underreport the number of drugged drivers who were injured in a motor vehicle collision. [ABSTRACT FROM PUBLISHER]

Gender-based differences in immunotoxicity induced by the heavy metal lead (Pb) have been observed both in the juvenile chicken and the adult rat following low-level exposure during embryonic development. To better define the gender-based differences, as related to dose following in utero exposure to Pb, potential differential sensitivities were examined after exposure of F344 rats to low concentrations of Pb (0, 50, 100, or 250 ppm Pb) ad libitum throughout gestation. Immune assessment was performed in juveniles (5 wk old) and young adults (13 wk old). At the highest (250 ppm) Pb concentration examined, the delayed-type hypersensitivity (DTH) response was depressed in females relative to gender-matched controls at both ages; relative spleen weights and relative neutrophil numbers were increased while relative and absolute monocyte numbers and relative basophil numbers were decreased at 13 but not 5 wk of age. In contrast, 250 ppm Pbtreated males did not differ in these endpoints. With in utero exposure to 100 ppm Pb, 13- wk-old females again had decreased relative and absolute monocyte numbers and increased relative neutrophil numbers, although the DTH response was unchanged. Males (with 100 ppm Pb) had increased relative neutrophil numbers, decreased relative lymphocytes, and transiently increased nitrite production seen at 5, but not 13, wk of age. After gestational exposure to 50 ppm Pb, minimal immunotoxic effects were observed in either males or females at either developmental age assessed. These results suggest that differential gender-based immunotoxicity profiles exist after gestational Pb exposure depending on the concentration of Pb administered to the dam. In utero exposure of dams to 250 ppm Pb results in more profound immunotoxicity in females than males. Males are not more sensitive to lower concentrations of Pb than females. Since the 50 ppm exposure produced minimal changes, these data may provide information to establish a noobserved-adverse-effect level (NOAEL) for in utero exposure to Pb. Additionally, while most effects were evident at both juvenile and adult ages, some changes were not fully evident until measured in the adult. Most changes were persistent with only one exception (male nitrite levels at 100 ppm). [ABSTRACT FROM AUTHOR]

Lead has been shown previously to induce immunotoxic effects on macrophage and T-cell-associated functions after full-gestational exposure. To gain a better understanding of a single developmental exposure and the potential role of gender in immunotoxic responses to low levels of lead, 5-d-old avian embryos were injected once with lead acetate (5 or 10 μg). As juveniles (4 wk of age), animals were immunized with a foreign antigen, bovine serum albumin (BSA). At 6 and 8 wk, animals were sensitized with a self antigen, thyroglobulin (Tg). Immune parameters were examined at 6 and 10 wk of age. In males, anti-BSA immunoglobulin G (IgG) levels were significantly increased at the highest lead treatment level compared to sodium acetate controls, while female antibody production was unaltered. Similarly, after early exposure to lead, males (which were noninducible for anti-thyroglobulin antibodies in sodium acetate controls) were induced to produce autoanti-thyroglobulin IgG. Lead exposure did not markedly alter autoantibody levels in females, although, unlike males, control females could be induced to produce autoantibody to thyroglobulin. Males differed significantly in total leukocyte counts between treatment groups, whereas females did not. No marked differences were observed in males or females in the delayed-type hypersensitivity response, lymphocytic infiltration of thyroids, or in spleen, thymus, or bursa weights following exposure to lead. These results suggest that there is a differential immunotoxic effect based on gender after a single in ovo exposure to lead. Therefore, when examining the developmental immunotoxic effects of a metal such as lead, gender is a potential risk factor. [ABSTRACT FROM AUTHOR]

The naturally occurring polymorphism at codon 129 of the human prion protein gene (PRNP) influences susceptibility to sporadic Creutzfeldt–Jakob Disease (CJD); the majority of the patients are methionine homozygotes at this locus, while valine homozygotes represent only 10% of cases. The aim was to study the clinical and neuropathological phenotype of sporadic CJD in valine homozygotes, to estimate the reliability of current clinical diagnostic criteria, and to identify any consistent and distinct features. Twelve cases of sporadic CJD with a codon 129 valine homozygote genotype were identified at the National CJD Surveillance Unit in Edinburgh. In addition to a retrospective clinical analysis, tissue blocks were stained by conventional techniques and by immunocytochemistry for prion protein. Frozen brain tissue was available from five cases for Western blot analysis of PrPRES, which in all cases showed a type 2 mobility. The cases included four males and eight females, average age 63.6 years, with a mean duration of illness of 6 months. Eleven patients presented with ataxia, and none had the characteristic EEG changes found in sporadic CJD. The neuropathological phenotype comprised spongiform change and prion protein immunopositivity most marked in the subcortical grey matter and cerebellum, prion protein positive plaque-like deposits in all regions, laminar deposition of prion protein in the cerebral cortex, and hippocampal involvement (which is seldom reported in sporadic CJD). In conclusion, these cases exhibited a fairly uniform phenotype, which is relatively distinct from sporadic CJD in methionine homozygotes, and thus diagnosis may be difficult using existing clinical criteria. [ABSTRACT FROM AUTHOR]

Sociologists have been interested in education for a long time. Among the main issues have been inequality of opportunity, transmission of culture and socialisation. Until quite recently Special Education has been largely overlooked. As an illustration of this, the education section of the bibliography of Recent British Sociology, (Eldridge, 1980) contains only one book which makes explicit reference to special education in its title, How the West Indian Child is Made Educationally Sub‐Normal in British Schools (Coard, 1971). This article attempts to summarise how sociologists have begun to take special education as an area worth studying. In the first part, Tomlinson's work, which is perhaps more a ‘pure sociology’ approach than any other, is described and analysed in some detail. In the second part, the work of more pragmatic authors is considered. Finally a ‘programme’ of empirical questions and possible methods for the sociology of special education is suggested. [ABSTRACT FROM PUBLISHER]

Lead has been shown to exert toxic effects during early development. In these in vivo and ex vivo experiments, the effect of lead on the immune system of the developing embryo was assessed. Nine-week-old female Fischer 344 rats were exposed to lead acetate (0,100,250, and 500 ppm lead) in their drinking water during breeding and pregnancy (exposure was discontinued at parturition). Offspring received no additional lead treatment after birth. Immune function was assessed in female offspring at 13 weeks of age. Dams in lead-exposed groups were not different from controls with respect to the immune endpoints used in these experiments; however, in the offspring, lead modulated important immune parameters at modest exposure levels. Macrophage cytokine and effector function properties (tumor necrosis factor-α and nitric oxide production) were elevated in the 250 ppm group, while cell-mediated immune function was depressed, as shown by a decrease in delayed-type hypersensitivity reactions in the 250 ppm group. Interferon-γ levels were decreased in the 500 ppm treatment group. Serum levels of IgE were increased in rats exposed to 100 ppm lead. These results indicate that exposure of mothers to moderate levels of lead produces chronic immune modulation in their F344 rat offspring exposed in utero. Since the mothers were not susceptible to chronic immune alterations, a developmental bias to the immunotoxic effects of lead is indicated. The differences observed are consistent with the possibility that lead may bias T helper subset development and/or function, resulting in alterations in the balance among type 1 and type 2 immune responses. [ABSTRACT FROM PUBLISHER]

Direct measurements of hydrodynamic instability growth at the fuel-ablator interface in inertial confinement fusion (ICF) implosions are reported for the first time. These experiments investigate one of the degradation mechanisms behind the lower-than-expected performance of early ICF implosions on the National Ignition Facility. Face-on x-ray radiography is used to measure instability growth occurring between the deuterium-tritium fuel and the plastic ablator from well-characterized perturbations. This growth starts in two ways through separate experiments--either from a preimposed interface modulation or from ablation front feedthrough. These experiments are consistent with analytic modeling and radiation-hydrodynamic simulations, which say that a moderately unstable Atwood number and convergence effects are causing in-flight perturbation growth at the interface. The analysis suggests that feedthrough from outersurface perturbations dominates the interface perturbation growth at mode 60. [ABSTRACT FROM AUTHOR]