An integrated development facility for the calibration of low-energy charged particle flight instrumentation

A system was developed for the calibration and development of thermal ion instrumentation. The system provides an extended beam with usable current rates, approx. 1 pA/sq cm, at beam energies as low as 1 eV, with much higher values available with increasing energy. A tandem electrostatic and variable geometry magnetic mirror configuration within the ion source optimizes the use of the ionizing electrons. The system is integrated under microcomputer control to allow automatic control and monitoring of the beam energy and composition and the mass and angle-dependent response of the instrument under test. The system is pumped by a combination of carbon vane and cryogenic sorption roughing pumps and ion and liquid helium operating pumps

Deep subsurface microbiology : a guide to the research topic papers

© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Microbiology 4 (2013): 122, doi:10.3389/fmicb.2013.00122.Deep subsurface microbiology is a rising field in geomicrobiology, environmental microbiology and microbial ecology that focuses on the molecular detection and quantification, cultivation, biogeographic examination, and distribution of bacteria, archaea, and eukarya that permeate the subsurface biosphere. The deep biosphere includes a variety of subsurface habitats, such as terrestrial deep aquifer systems or mines, deeply buried hydrocarbon reservoirs, marine sediments and the basaltic ocean crust. The deep subsurface biosphere abounds with uncultured, only recently discovered and—at best—incompletely understood microbial populations. So far, microbial cells and DNA remain detectable at sediment depths of more than 1 km and life appears limited mostly by heat in the deep subsurface. Severe energy limitation, either as electron acceptor or donor shortage, and scarcity of microbially degradable organic carbon sources are among the evolutionary pressures that may shape the genomic and physiological repertoire of the deep subsurface biosphere. Its biogeochemical importance in long-term carbon sequestration, subsurface elemental cycling and crustal aging, is a major focus of current research at the interface of microbiology, geochemistry, and biosphere/geosphere evolution

Clustering and correlates of screen-time and eating behaviours among young children

Background: Screen-time and unhealthy dietary behaviours are highly pervasive in young children and evidence suggests that these behaviours often co-occur and are associated. Identifying clusters of unhealthy behaviours, and their influences early in childhood, can assist in the development of targeted preventive interventions. The purpose of this study was to examine the sociodemographic, behavioural, and home physical environmental correlates of co-occurring screen-time and unhealthy eating behaviours and to assess the clustering of screen-time and unhealthy dietary behaviours in young children. Methods: Parents of 126 children, from the UK, aged 5–6 years (49% boys) completed a questionnaire which assessed their child’s screen-time (ST), fruit and vegetable (FV), and energy-dense (ED) snack consumption. Categories of health behaviours were created based on frequencies of children meeting recommendations for FV and ST and median splits of frequencies for ED snacks. Parents reported on their own behaviours (ST, FV, and ED snack consumption), how often they ate meals and watched TV with their child, and on the availability and accessibility of foods within the home. An observed over expected ratio (O/E) was used to assess behavioural clustering. Multivariable multinomial logistic regression was used to examine correlates of behaviour patterns. Results: Approximately 25% of children had two or three health risk behaviours. Correlates consistently associated with clusters included parental income, eating meals at the TV, parental ST and ED snack food consumption, and home availability of ED snack foods. Observed over expected ratios were close to 1 and ranged from 0.78 to 1.43. The three-risk behaviour combination of insufficient FV consumption, high ED snack consumption, and excessive ST occurred more frequently than expected (1.23 (95% CI 0.89, 1.58)). Conclusions: ST and unhealthy dietary behaviours cluster in children as young as 5 years of age and parents’ own behaviours appear to be important influencing factors. Further research into the development of behavioural clustering in young children to identify and further understand the mechanisms underlying the synergy among health behaviours is needed. Feasibility interventions promoting reductions in both screen-time and unhealthy dietary behaviours reciprocally, while simultaneously focusing on changing parental behaviours, are warranted

Cultivation-dependent and cultivation-independent characterization of hydrocarbon-degrading bacteria in Guaymas Basin sediments

Marine hydrocarbon-degrading bacteria perform a fundamental role in the biodegradation of crude oil and its petrochemical derivatives in coastal and open ocean environments. However, there is a paucity of knowledge on the diversity and function of these organisms in deep-sea sediment. Here we used stable-isotope probing (SIP), a valuable tool to link the phylogeny and function of targeted microbial groups, to investigate polycyclic aromatic hydrocarbon (PAH)-degrading bacteria under aerobic conditions in sediments from Guaymas Basin with uniformly labeled [13C]phenanthrene. The dominant sequences in clone libraries constructed from 13C-enriched bacterial DNA (from phenanthrene enrichments) were identified to belong to the genus Cycloclasticus. We used quantitative PCR primers targeting the 16S rRNA gene of the SIP-identified Cycloclasticus to determine their abundance in sediment incubations amended with unlabeled phenanthrene and showed substantial increases in gene abundance during the experiments. We also isolated a strain, BG-2, representing the SIP-identified Cycloclasticus sequence (99.9% 16S rRNA gene sequence identity), and used this strain to provide direct evidence of phenanthrene degradation and mineralization. In addition, we isolated Halomonas, Thalassospira and Lutibacterium spp. with demonstrable phenanthrene-degrading capacity from Guaymas Basin sediment. This study demonstrates the value of coupling SIP with cultivation methods to identify and expand on the known diversity of PAH-degrading bacteria in the deep-sea

Do Clawback Adoptions Influence Capital Investments?

We present evidence that clawback provision adoptions influence capital investment mix via managerial compensation incentives. Specifically, we find for a propensity-matched sample of 931 voluntary clawback adoptions that capital investments shift away from R&D and toward capital expenditures, and for firms with enabling liquidity toward acquisitions, consistent with clawback effects on earnings-linked compensation. Corroborating evidence confirms that these effects are positively related to performance-based pay, growth opportunities, and invariant to risk-toleration incentives, with firms adopting clawbacks also exhibiting capital over-investment. This evidence is timely given a pending SEC rule that would mandate clawbacks for all firms listing on US exchanges.postprin

DE 1 RIMS operational characteristics

The Retarding Ion Mass Spectrometer (RIMS) on the Dynamics Explorer 1 spacecraft observes both the thermal and superthermal (50 eV) ions of the ionosphere and inner magnetosphere. It is capable of measuring the detailed species distribution function of these ions in many cases. It was equipped with an integral electrometer to permit in-flight calibration of the detector sensitivities and variations thereof. A guide to understanding the RIMS data set is given. The reduction process from count rates to physical quantities is discussed in some detail. The procedure used to establish in-flight calibration is described, and results of a comparison with densities from plasma wave measurements are provided. Finally, a discussion is provided of various anomalies in the data set, including changes of channeltron efficiency with time, spin modulation of the axial sensor heads, apparent potential differences between the sensor heads, and failures of the radial head retarding potential sweep and of the -Z axial head aperture plane bias. Studies of the RIMS data set should be conducted only with a thorough awareness of the material presented here, or in collaboration with one of the scientists actively involved with RIMS data analysis