68,646 research outputs found
The Frozen Core Approximation and Nuclear Screening Effects in Single Electron Capture Collisions
Fully Differential Cross Sections (FDCS) for single electron capture from
helium by heavy ion impact are calculated using a frozen core 3-Body model and
an active electron 4-Body model within the first Born approximation. FDCS are
presented for H+, He2+, Li3+, and C6+ projectiles with velocities of 100
keV/amu, 1 MeV/amu, and 10 MeV/amu. In general, the FDCS from the two models
are found to differ by about one order of magnitude with the active electron
4-Body model showing better agreement with experiment. Comparison of the models
reveals two possible sources of the magnitude difference: the inactive
electron's change of state and the projectile-target Coulomb interaction used
in the different models. Detailed analysis indicates that the uncaptured
electron's change of state can safely be neglected in the frozen core
approximation, but that care must be used in modeling the projectile-target
interaction
Radial Velocities of Newly Discovered Globular Clusters in NGC 5128
We present radial velocity measurements for 74 globular clusters (GCs) in the
nearby giant elliptical NGC 5128, of which 31 are newly discovered clusters.
All the GC candidates were taken from the list of possible new clusters given
in the Harris, Harris, & Geisler (2004) photometric survey. In addition to the
newly confirmed clusters, we identified 24 definite foreground stars and 31
probable background galaxies. From a combined list of 299 known GCs in NGC 5128
with measured radial velocities and metallicity-sensitive (C - T_1) photometric
indices, we construct a new metallicity distribution function (MDF) for the
cluster system. The MDF shows an approximately bimodal form, with centroids at
[Fe/H] = -1.46 and -0.53, and with nearly equal numbers of metal-poor and
metal-rich clusters in the two modes. However, there are many
intermediate-color clusters in the distribution, and the fainter clusters tend
to have a higher proportion of red clusters. These features of the MDF may
indicate a widespread age range within the cluster system as well as an
intrinsically broad metallicity spread.Comment: 10 pages, 7 figures, 4 tables - accepted in Astronomical Journa
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Employers' policies for third age employment â the case for action and the rational for reaction
This paper reports on findings from a study which explores employersâ perceptions of the careers of those in third age employment and the extent to which these organisations have in place policies and practices to manage older worker careers. Drawing on interviews with UK HR managers and advisory bodies, the study finds that there was an absence of formal policies which addressed the career needs of older works despite employers being aware of the issue associated with an aging workforce. Instead employers responded to career related requests from older workers on an ad hoc basis as they felt that specific policies for this group of people would potentially create legal issues for the organisation. Employers also believed that the aged workforce had little impact on their business and as a result did not engage in collective dialogue with older workers about their requirements and instead made assumptions about their career needs
Does settlement plate material matter? The influence of substrate type on fouling community development
Benthic community composition and ascidian abundance can differ dramatically between adjacent man-made and natural substrates. Although multiple factors, including light exposure, surface orientation, predation exposure, and habitat type, are known to contribute to these patterns, few studies have directly tested the influence of substrate identity on community development. We compared fouling communities on settlement plates composed of commonly occurring natural (granite) and artificial (concrete, high density polyethylene, and PVC) marine materials deployed from late May to mid November 2014 from a floating dock in Newcastle, NH. We sought to determine if observed patterns resulted from differential recruitment onto substrate materials or post-settlement survival and growth. To do this, half of the plates were cleaned during bi-weekly examinations, and half were left un-cleaned. Preliminary analyses indicate that community composition differs between substrate types. These results will help us understand how substrate features contribute to non-native species establishment and habitat dominance, and may inform decisions regarding material usage in marine construction. These findings also underline the importance of settlement substrate choice in scientific studies, as plate material may influence experimental conclusions
Spine-sheath layer radiative interplay in subparsec-scale jets and the TeV emission from M87
Simple one-zone homogeneous synchrotron self-Compton models have severe
difficulties in explaining the TeV emission observed in the radiogalaxy M87.
Also the site of the TeV emission region is uncertain: it could be the
unresolved jet close to the nucleus, analogously to what proposed for blazars,
or an active knot, called HST-1, tens of parsec away. We explore the
possibility that the TeV emission of M87 is produced in the misaligned subpc
scale jet. We base our modelling on a structured jet, with a fast spine
surrounded by a slower layer. In this context the main site responsible for the
emission of the TeV radiation is the layer, while the (debeamed) spine accounts
for the emission from the radio to the GeV band: therefore we expect a more
complex correlation with the TeV component than that expected in one-zone
scenarios, in which both components are produced by the same region. Observed
from small angles, the spine would dominate the emission, with an overall
Spectral Energy Distribution close to those of BL Lac objects with a
synchrotron peak located at low energy (LBLs).Comment: 5 pages, 2 figures. Accepted for publication in MNRAS Letter
A qualitative study exploring why adults with intellectual disabilities and obesity want to lose weight and views of their carers
Background:
Obesity is more prevalent in adults with intellectual disabilities (ID) compared to the general population. Motivations for weight loss may influence engagement with weight management programmes and have only been studied in adults without ID. Aims: To determine reasons given by adults with ID and obesity for seeking weight loss and whether these reasons differ from those of their carers.
Methods:
Prior to a multi-component weight management intervention, participants were asked âwhy do you want to lose weight?â Carers were asked their views and these were compared to the answers given by the adult with ID. Responses were themed. The Fisherâs Exact analysis was used to test for any relationship between reasons for seeking weight loss and participantsâ level of ID, age, gender and BMI.
Results:
Eighteen men and 32 women; age 41.6 SD 14.6 years; BMI 40.8 SD 7.5 kg/m2; Level ID Mild (28 %), Moderate (42 %), Severe (22 %), Profound (8 %). Eleven were unable to respond. Six themes emerged; Health; Fitness / Activity / Mobility; Appearance / Clothes; Emotional / Happiness; For Others; Miscellaneous. The most frequent reason given overall and by women was âappearance.â Carers cited âhealthâ most frequently and âappearanceâ least, rarely agreeing with participants. âHealthâ was given as a reason more from older adults and those with milder ID. No statistically significant associations were found between reasons for seeking weight loss and BMI age, gender or level of ID but the differing views of adults with ID and their carers were clear.
Conclusions:
Views of adults with obesity and mild or moderate ID can be collected. The opposing views of adults and their carers may affect motivation for weight loss
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