Mesoscale subduction at the Almeria-Oran front. Part 2: biophysical interactions.

This paper presents a detailed diagnostic analysis of hydrographic and current meter data from three, rapidly repeated, fine-scale surveys of the Almeria–Oran front. Instability of the frontal boundary, between surface waters of Atlantic and Mediterranean origin, is shown to provide a mechanism for significant heat transfer from the surface layers to the deep ocean in winter. The data were collected during the second observational phase of the EU funded OMEGA project on RRS Discovery cruise 224 during December 1996. High resolution hydrographic measurements using the towed undulating CTD vehicle, SeaSoar, traced the subduction of Mediterranean Surface Water across the Almeria–Oran front. This subduction is shown to result from a significant baroclinic component to the instability of the frontal jet. The Q-vector formulation of the omega equation is combined with a scale analysis to quantitatively diagnose vertical transport resulting from mesoscale ageostrophic circulation. The analyses are presented and discussed in the presence of satellite and airborne remotely sensed data; which provide the basis for a thorough and novel approach to the determination of observational error

Physical activity attenuates the influence of FTO variants on obesity risk: A meta-analysis of 218,166 adults and 19,268 children

Background: The FTO gene harbors the strongest known susceptibility locus for obesity. While many individual studies have suggested that physical activity (PA) may attenuate the effect of FTO on obesity risk, other studies have not been able to confirm this interaction. To confirm or refute unambiguously whether PA attenuates the association of FTO with obesity risk, we meta-analyzed data from 45 studies of adults (n = 218,166) and nine studies of children and adolescents (n = 19,268). Methods and Findings: All studies identified to have data on the FTO rs9939609 variant (or any proxy [r2>0.8]) and PA were invited to participate, regardless of ethnicity or age of the participants. PA was standardized by categorizing it into a dichotomous variable (physically inactive versus active) in each study. Overall, 25% of adults and 13% of children were categorized as inactive. Interaction analyses were performed within each study by including the FTO×PA interaction term in an additive model, adjusting for age and sex. Subsequently, random effects meta-analysis was used to pool the interaction terms. In adults, the minor (A-) allele of rs9939609 increased the odds of obesity by 1.23-fold/allele (95% CI 1.20-1.26), but PA attenuated this effect (pinteraction= 0.001). More specifically, the minor allele of rs9939609 increased the odds of obesity less in the physically active group (odds ratio = 1.22/allele, 95% CI 1.19-1.25) than in the inactive group (odds ratio = 1.30/allele, 95% CI 1.24-1.36). No such interaction was found in children and adolescents. Concl

Electron accelerator based system for assay of transuranic waste barrels

A complete assay system for 208-liter barrels contianing transuranic wastes has been developed. The system consists of an 8-MeV commercial electron accelerator, neutron moderating cavity housing the waste barrel and containing neutron detectors, high resolution germanium gamma spectrometer, and x-ray radiography camera (both film and real time). The electron linac is used to produce bremsstrahlung and high-intensity pulsed neutron flux, both of which are used to interrogate the fissionable materials. The Differential Dieaway Technique is used to assay the amounts of fissile and fertile materials. The neutron flux is also used in the Prompt Gamma Activation Assay to determine and to quantify the matrix elements present in the barrels. This information is then used to correct the assay of fissionable material. The bremsstrahlung too, is also used by x-ray radiography system to further identify the matrix

Application of linear accelerator technology to the detection of trace amounts of transuranics in waste barrels

Electron linear accelerators (linacs), as sources of photons and neutrons, can produce a significant number of fissions in transuranic isotopes contained in large barrels of waste material. Both photons and thermal neutrons have been used to detect about 1 mg of plutonium in 105-kg matrices. A sequential interrogation with neutrons and photons, easily possible with linacs, can show both fertile and fissile constituents among the heavy-mass isotopes. The advantages of linacs in solving existing assay problems include: (1) high available beam current; (2) variable beam current, beam energy, pulse width, and pulse repetition frequency; and (3) beam-scanning ability. They also are compatible with passive assay instruments. Their versatility makes it likely that they will remain useful as assay technology advances

Recent developments at Los Alamos for the measurement of alpha contaminated waste

A comprehensive program is currently in progress for the development of sensitive, practical nondestructive assay techniques for the quantification of low level transuranics in bulk solid wastes. This program encompasses a broad range of nuclear and nonnuclear techniques including sophisticated passive gamma-ray and passive neutron detection systems, isotopic neutron source-based active interrogation systems, pulsed portable neutron generator active interrogation systems, electron accelerator based techniques and laser spectroscopy techniques. The mix of techniques ranges in development maturity from the well established (MEGAS, Shuffler, Passive 4..pi.. neutron counters) through the proof-of-principle stage (pulsed neutron generator techniques) to the under investigation stage (electron linac and laser spectroscopy techniques). Matrix compensation methods are being developed to improve the accuracy of waste screening and assay measurements. Specific detection systems have been designed to operate in the high level beta-gamma backgrounds associated with some commercial reactor wastes. The techniques being developed can be used with either low level or high level beta-gamma wastes in either low density or high density matrices

Advances in measurement of alpha-contaminated wastes

A comprehensive program is in progress at the Los Alamos National Laboratory for the development of sensitive, practical, nondestructive assay techniques for the quantification of low-level transuranics in bulk solid wastes. The program encompasses a broad range of techniques, including sophisticated active and passive gamma-ray spectroscopy, passive neutron detection systems, pulsed portable neutron generator interrogation systems, and electron accelerator-based techniques. The techniques can be used with either low-level or high-level beta-gamma wastes in either low-density or high-density matrices