A compact filtered x-ray diode array spectrometer for the National Ignition Facility: SENTINEL.

Sentinel is a 16-channel, filtered x-ray diode array spectrometer that has been developed to measure ∼1 keV-20 keV x-ray emission generated by the National Ignition Facility (NIF) laser. Unlike the large, fixed-port versions of this diagnostic that currently exist on the NIF (known as Dante), Sentinel is a Diagnostic Instrument Manipulator compatible such that it can be fielded along the polar or equatorial lines-of-sight-an essential new capability for characterizing the often anisotropic x-ray emission from laser-driven sources. We present the diagnostic design along with preliminary diode calibrations and performance results. The novel, small-form-factor x-ray diode design allows for ≳5×-25× increased channel areal density over that of Dante, simultaneously enabling improved diagnostic robustness and fidelity of spectral reconstructions. While the Sentinel diagnostic is anticipated to improve line-of-sight spectral characterization of x-ray sources for a wide variety of programs on the NIF, the compact and portable design is also attractive to small- and mid-scale facilities with limited diagnostic real estate.

The effect of predator exposure and reproduction on oxidative stress parameters in the Catarina scallop Argopecten ventricosus.

Predation is known to impact growth and reproduction, and the physiological state of the prey, including its susceptibility to oxidative stress. In this study, we investigated how prolonged exposure to predators modulates tissue specific antioxidant defense and oxidative damage in the short-lived epibenthic scallop Argopecten ventricosus (2years maximum lifespan). Scallops that were experimentally exposed to predators had not only lower antioxidant capacities (superoxide dismutase and catalase), but also lower oxidative damage (protein carbonyls and TBARS=thiobarbituric acid reactive substances including lipid peroxides) in gills and mantle compared to individuals not exposed to predators. In contrast, oxidative damage in the swimming muscle was higher in predator-exposed scallops. When predator-exposed scallops were on the verge of spawning, levels of oxidative damage increased in gills and mantle in spite of a parallel increase in antioxidant defense in both tissues. Levels of oxidative damage increased also in the swimming muscle whereas muscle antioxidant capacities decreased. Interestingly, post-spawned scallops restored antioxidant capacities and oxidative damage to immature levels, suggesting they can recover from spawning-related oxidative stress. Our results show that predator exposure and gametogenesis modulate oxidative damage in a tissue specific manner and that high antioxidant capacities do not necessarily coincide with low oxidative damage.

Changes in oxidative stress parameters in relation to age, growth and reproduction in the short-lived catarina scallop Argopecten ventricosus reared in its natural environment.

Increase in oxidative damage and decrease in cellular maintenance is often associated with aging, but, in marine ectotherms, both processes are also strongly influenced by somatic growth, maturation and reproduction. In this study, we used a single cohort of the short-lived catarina scallop Argopecten ventricosus, to investigate the effects of somatic growth, reproduction and aging on oxidative damage parameters (protein carbonyls, TBARS and lipofuscin) and cellular maintenance mechanisms (antioxidant activity and apoptosis) in scallops, caged in their natural environment. The concentrations of protein carbonyls and TBARS increased steeply during the early period of fast growth and during reproduction in one-year-old scallops. However, oxidative damage was transient, and apoptotic cell death played a pivotal role in eliminating damage in gill, mantle and muscle tissues of young scallops. Animals were able to reproduce again in the second year, but the reduced intensity of apoptosis impaired subsequent removal of damaged cells. In late survivors low antioxidant capacity and apoptotic activity together with a fast accumulation of the age pigment lipofuscin was observed. Rates of oxygen consumption and oxidative stress markers were strongly dependent on somatic growth and reproductive state but not on temperature. Compared to longer-lived bivalves, A. ventricosus seems more susceptible to oxidative stress with higher tissue-specific protein carbonyl levels and fast accumulation of lipofuscin in animals surviving the second spawning. Superoxide dismutase activity and apoptotic cell death intensity were however higher in this short-lived scallop than in longer-lived bivalves. The life strategy of this short-lived and intensely predated scallop supports rapid somatic growth and fitness as well as early maturation at young age at the cost of fast cellular degradation in second year scallops.

Indium determination in different environmental materials by electrothermal atomic absorption spectrometry with Amberlite XAD-2 coated with 1-(2-pyridylazo)-2-naphthol.

Methods were developed for indium (In) determination in complex ores by electrothermal atomization atomic absorption spectrometry using matrix modification after its separation with Amberlite XAD-2 coated with 1-(2-pyridylazo)-2-naphthol (PAN). Palladium-magnesium, nickel, and zinc nitrates were used as matrix modifiers and were compared in terms of maximum pyrolysis temperature, sensitivity and background signal. They have enhanced the absorption signals for indium, respectively eliminating the matrix interferences. The standard additions method was applied. The relative standard deviations for six replicate determinations were in the range 0.3-4.0% for indium in different ores samples for indium concentrations 7.6-209mugg(-1). The recommended method was applied to the indium determination in real samples. The data obtained by this method were in good agreement with those obtained by ICP-AES.

Comparative susceptibility of veliger larvae of four bivalve mollusks to a Vibrio alginolyticus strain.

The susceptibility of 7 d old veliger larvae of the scallops Argopecten ventricosus and Nodipecten subnodosus, the penshell Atrina maura, and the Pacific oyster Crassostrea gigas to a pathogenic strain of Vibrio alginolyticus was investigated by challenging the larvae with different bacterial concentrations in a semi-static assay. The results indicate that the larvae of the 2 scallop species are more susceptible to the V. alginolyticus strain than those of the oyster and the penshell. Signs of the disease were similar to bacillary necrosis described in previous work. Interspecies differences in susceptibility to pathogens are discussed.

Sex differences in the epidemiology of tuberculosis in San Francisco.

SETTING: Worldwide differences in sex-specific tuberculosis case rates remain fundamentally unexplained. OBJECTIVE: To explore various factors that may explain sex differences in tuberculosis incidence rates for San Francisco from 1991-1996. DESIGN: A retrospective epidemiologic analysis of sex-specific tuberculosis incidence rates in San Francisco from 1991-1996. Stratified analyses were performed on age at diagnosis, racial/ethnic group, human immunodeficiency virus (HIV) status, and place of birth. Molecular fingerprinting with IS6110 data was used to study sex differences in the incidence of disease for recently transmitted and reactivated cases of tuberculosis. RESULTS: In the study period, the male to female incidence rate ratio was 2.1 (95% CI 1.9-2.3). Stratified analyses revealed differences in sex-specific rates after the age of 14 and the highest male:female ratios were seen in the US-born, white, and black populations. High ratios were also observed for cases with clustered fingerprints, similar to those observed for the US-born population. In sub-populations with predominantly reactivated cases of tuberculosis, ratios were also above unity after adolescence, but the effect was less pronounced. CONCLUSION: The ongoing transmission of tuberculosis in the US-born population is one of the factors that explains the difference in sex-specific rates of disease in San Francisco. Observed differences in tuberculosis rates between the sexes may be due to a difference in transmission dynamics rather than diagnosis or reporting biases.