Proposed reference models for atomic oxygen in the terrestrial atmosphere

A provisional Atomic Oxygen Reference model was derived from average monthly ozone profiles and the MSIS-86 reference model atmosphere. The concentrations are presented in tabular form for the altitude range 40 to 130 km

Trapping of Pd, Au, and Cu by implantation-induced nanocavities and dislocations in Si

The gettering of metallic impurities by nanocavities formed in Si is a topic of both scientific importance and technological significance. Metallic precipitates observed in the regions where nanocavities were formed have been considered the result of the metal filling the nanocavities, either as elemental metal or a silicide phase. However, our transmission electron microscopy observations demonstrate that many of these precipitates are concentrated along dislocations, rather than randomly distributed as expected for precipitates formed by the filling of nanocavities. Consequently, the gettering contribution of dislocations in the lattice caused by nanocavity formation must be considered. For Pd, dislocations are the preferred sites for the precipitation of the metal silicide. We compare results of gettering by nanocavities and dislocations for Pd, Au, and Cu to determine which structure is the dominant influence for the formation of precipitates of these metals and/or their silicides

Unmasking quality: exploring meanings of health by doing art

This paper arises from a presentation at the ‘Quality in Healthcare’ symposium at Cumberland Lodge, England, in 2013. MK, CR and SH conceived the paper and led the writing of the manuscript. JF, JL-D, AC, DE contributed substantially to the intellectual content of the paper through providing critical commentary and interpretation. All authors read and approved the final manuscript

Gettering of Pd to implantation-induced nanocavities in Si

The gettering of Pd to nanocavities in Si for implantation doses ranging from 5×10¹³ to 1×10¹⁵ cm¯² and annealing temperatures ranging from 750 to 1050 °C was investigated using Rutherford backscattering and cross-sectional transmission electron microscopy. For a given annealing temperature, the gettering efficiency increased as the dose decreased. For a given dose, maximum gettering efficiency was achieved at the intermediate temperatures studied. Competition between silicide formation and nanocavity gettering limited gettering efficiency.The authors thank the Australian Research Council for their financial support. G.deM.A. acknowledges the Brazilian agency CNPq ~Conselho Nacional de Desenvolvimento Cientı´fico e Tecnolo´gico! for a postdoctoral fellowship

Retrieval of stratospheric aerosol size information from OSIRIS limb scattered sunlight spectra

International audienceRecent work has shown that the retrieval of stratospheric aerosol vertical profiles is possible using limb scattered sunlight measurements at optical wavelengths. The aerosol number density profile is retrieved for an assumed particle size distribution and composition. This result can be used to derive the extinction at the measured wavelength. However, large systematic error can result from the uncertainty in the assumed size distribution when the result is used to estimate the extinction at other wavelengths. It is shown in this work that the addition of information obtained from the near infrared limb radiance profile at 1530 nm measured by the imaging module of the OSIRIS instrument yields an indication of the aerosol size distribution profile that can be used to improve the fidelity of the retrievals. A comparison of the estimated extinction profile at 1020 nm with coincident occultation measurements demonstrates agreement to within approximately 15% from 12 to 27 km altitude

Amorphization of embedded Cu nanocrystals by ion irradiation

While bulk crystalline elemental metals cannot be amorphized by ion irradiation in the absence of chemical impurities, the authors demonstrate that finite-size effects enable the amorphization of embedded Cu nanocrystals. The authors form and compare the atomic-scale structure of the polycrystalline, nanocrystalline, and amorphous phases, present an explanation for the extreme sensitivity to irradiation exhibited by nanocrystals, and show that low-temperature annealing is sufficient to return amorphized material to the crystalline form

Gauge covariant fermion propagator in quenched, chirally-symmetric quantum electrodynamics

We discuss the chirally symmetric solution of the massless, quenched, Dyson-Schwinger equation for the fermion propagator in three and four dimensions. The solutions are manifestly gauge covariant. We consider a gauge covariance constraint on the fermion--gauge-boson vertex, which motivates a vertex Ansatz that both satisfies the Ward identity when the fermion self-mass is zero and ensures gauge covariance of the fermion propagator.Comment: 11 pages. REVTEX 3.0. ANL-PHY-7711-TH-9

Pt nanocrystals formed by ion implantation: a defect-mediated nucleation process

The influence of ion irradiation of SiO₂ on the size of metalnanocrystals (NCs) formed by ion implantation has been investigated. Thin SiO₂ films were irradiated with high-energy Ge ions then implanted with Pt ions. Without Geirradiation, the largest Pt NCs were observed beyond the Pt projected range. With irradiation, Ge-induced structural modification of the SiO₂ layer yielded a decrease in Pt NC size with increasing Ge fluence at such depths. A defect-mediated NC nucleation mechanism is proposed and a simple yet effective means of modifying and controlling the Pt NC size is demonstrated.The authors thank the Australian Research Council for financial support

Ground-state Spectrum of Light-quark Mesons

A confining, Goldstone theorem preserving, separable Ansatz for the ladder kernel of the two-body Bethe-Salpeter equation is constructed from phenomenologically efficacious $u$, $d$ and $s$ dressed-quark propagators. The simplicity of the approach is its merit. It provides a good description of the ground-state isovector-pseudoscalar, vector and axial-vector meson spectrum; facilitates an exploration of the relative importance of various components of the two-body Bethe-Salpeter amplitudes, showing that sub-leading Dirac components are quantitatively important in the isovector-pseudoscalar meson channels; and allows a scrutiny of the domain of applicability of ladder truncation studies. A colour-antitriplet diquark spectrum is obtained. Shortcomings of separable Ans\"atze and the ladder kernel are highlighted.Comment: 30 pages, LaTeX/REVTEX 3.0, no figure

Behavioural Susceptibility Theory: Professor Jane Wardle and the Role of Appetite in Genetic Risk of Obesity

Purpose of Review: There is considerable variability in human body weight, despite the ubiquity of the 'obesogenic' environment. Human body weight has a strong genetic basis and it has been hypothesised that genetic susceptibility to the environment explains variation in human body weight, with differences in appetite being implicated as the mediating mechanism; so-called 'behavioural susceptibility theory' (BST), first described by Professor Jane Wardle. This review summarises the evidence for the role of appetite as a mediator of genetic risk of obesity. Recent Findings: Variation in appetitive traits is observable from infancy, drives early weight gain and is highly heritable in infancy and childhood. Obesity-related common genetic variants identified through genome-wide association studies show associations with appetitive traits, and appetite mediates part of the observed association between genetic risk and adiposity. Summary: Obesity results from an interaction between genetic susceptibility to overeating and exposure to an 'obesogenic' food environment