1,387 research outputs found
Recombination Rate Coefficients for KLL Di-electronic Satellite Lines of Fe XXV and Ni XXVII
The unified method for total electron-ion recombination is extended to study
the dielectronic satellite (DES) lines. These lines, formed from radiative
decay of autoionizing states, are highly sensitive temperature diagnostics of
astrophysical and laboratory plasma sources. The computation of the unified
recombination rates is based on the relativistic Breit-Pauli R-matrix method
and close coupling approximation. Extending the theoretical formulation
developed earlier we present recombination rate coefficients for the 22
satellite lines of KLL complexes of helium-like Fe XXV and Ni XXVII. The
isolated resonance approximation, commonly used throughout plasma modeling,
treats these resonances essentially as bound features except for dielectronic
capture into, and autoionization out of, these levels. A line profile or cross
section shape is often assumed. On the other hand, by including the coupling
between the autoionizing and continuum channels, the unified method gives the
intrinsic spectrum of DES lines which includes not only the energies and
strengths, but also the natural line or cross section shapes. A formulation is
presented to derive autoionization rates from unified resonance strengths and
enable correspondence with the isolated resonance approximation. While the
rates compare very well with existing rates for the strong lines to <20%, the
differences for weaker DES lines are larger. We also illustrate the application
of the present results to the analysis of K ALPHA complexes observed in
high-temperature X-ray emission spectra of Fe XXV and Ni XXVII. There are
considerable differences with previous results in the total KLL intensity for
Fe XXV at temperatures below the temperature of maximum abundance in coronal
equilibrium. (Abbreviated Abstract)Comment: 21 pages, 5 figures, to appear in Physica Script
Ionization state, excited populations and emission of impurities in dynamic finite density plasmas: I. The generalized collisional-radiative model for light elements
The paper presents an integrated view of the population structure and its role in establishing the ionization state of light elements in dynamic, finite density, laboratory and astrophysical plasmas. There are four main issues, the generalized collisional-radiative picture for metastables in dynamic plasmas with Maxwellian free electrons and its particularizing to light elements, the methods of bundling and projection for manipulating the population equations, the systematic production/use of state selective fundamental collision data in the metastable resolved picture to all levels for collisonal-radiative modelling and the delivery of appropriate derived coefficients for experiment analysis. The ions of carbon, oxygen and neon are used in illustration. The practical implementation of the methods described here is part of the ADAS Project
A novel role for syndecan-3 in angiogenesis.
Syndecan-3 is one of the four members of the syndecan family of heparan sulphate proteoglycans and has been shown to interact with numerous growth factors via its heparan sulphate chains. The extracellular core proteins of syndecan-1,-2 and -4 all possess adhesion regulatory motifs and we hypothesized that syndecan-3 may also possess such characteristics. Here we show that a bacterially expressed GST fusion protein consisting of the entire mature syndecan-3 ectodomain has anti-angiogenic properties and acts via modulating endothelial cell migration. This work identifies syndecan-3 as a possible therapeutic target for anti-angiogenic therapy.This work was funded by Arthritis Research-UK (Grant No. 19207) and funds from the William Harvey Research Foundation both to JRW
Using coloured filters to reduce the symptoms of visual stress in children with reading delay
Background: Meares Irlen Syndrome (MIS), otherwise known as “visual stress”, is one condition that can cause difficulties with reading. Aim: This study aimed to compare the effect of two coloured-filter systems on the symptoms of visual stress in children with reading delay. Methods: The study design was a pre-test, post-test, randomized head-to-head comparison of two filter systems on the symptoms of visual stress in school children. A total of 68 UK mainstream schoolchildren with significant impairment in reading ability completed the study. Results: The filter systems appeared to have a large effect on the reported symptoms between pre and post three-month time points (d = 2.5, r = 0.78). Both filter types appeared to have large effects (Harris d = 1.79, r = 0.69 and DRT d = 3.22, r = 0.85). Importantly, 35% of participants’ reported that their symptoms had resolved completely; 72% of the 68 children appeared to gain improvements in three or more visual stress symptoms. Conclusion and significance: The reduction in symptoms, which appeared to be brought about by the use of coloured filters, eased the visual discomfort experienced by these children when reading. This type of intervention therefore has the potential to facilitate occupational engagement
Dynamics and Radiation of Young Type-Ia Supernova Remnants: Important Physical Processes
We examine and analyze the physical processes that should be taken into
account when modeling young type-Ia SNRs, with ages of several hundred years.
It is shown, that energy losses in the metal-rich ejecta can be essential for
remnants already at this stage of evolution. The influence of electron thermal
conduction and the rate of the energy exchange between electrons and ions on
the temperature distribution and the X-radiation from such remnants is studied.
The data for Tycho SNR from the XMM-Newton X-ray telescope have been employed
for the comparison of calculations with observations.Comment: 19 pages, 8 figure
The National Food Consumption Survey (NFCS): South Africa, 1999
Objective: The aim of the National Food Consumption Survey (NFCS) in South Africa was to determine the nutrient intakes and anthropometric status of children (1-9 years old), as well as factors that influence their dietary intake. Design: This was a cross-sectional survey of a nationally representative sample of all children aged 1-9 years in South Africa. A nationally representative sample with provincial representation was selected using 1996 Census information. Subjects: Of the 3120 children who were originally sampled data were obtained from 2894, a response rate of 93%. Methods: The sociodemographic status of each household was assessed by a questionnaire. Dietary intake was assessed by means of a 24-hour recall and a food-frequency questionnaire from the caregivers of the children. Food purchasing practices were determined by means of a food procurement questionnaire. Hunger was assessed by a modified hunger scale questionnaire. Nutritional status was determined by means of anthropometric measurements: height, weight, head circumference and arm circumference. Results: At the national level, stunting (height-for-age below minus two standard deviations (< -2SD) from the reference median) was by far the most common nutritional disorder, affecting nearly one in five children. The children least affected (17%) were those living in urban areas. Even with regard to the latter, however, children living in informal urban areas were more severely affected (20%) compared with those living in formal urban areas (16%). A similar pattern emerged for the prevalence of underweight (weight-for-age < -2SD), with one in 10 children being affected at the national level. Furthermore, one in 10 (13%) and one in four (26%) children aged 1-3 years had an energy intake less than half and less than two-thirds of their daily energy needs, respectively. For South African children as a whole, the intakes of energy, calcium, iron, zinc, selenium, vitamins A, D, C and E, riboflavin, niacin, vitamin B6 and folic acid were below two-thirds of the Recommended Dietary Allowances. At the national level, data from the 24-hour recalls indicated that the most commonly consumed food items were maize, sugar, tea, whole milk and brown bread. For South African children overall, one in two households (52%) experienced hunger, one in four (23%) were at risk of hunger and only one in four households (25%) appeared food-secure. Conclusion: The NFCS indicated that a large majority of households were food-insecure and that energy deficit and micronutrient deficiencies were common, resulting in a high prevalence of stunting. These results were used as motivation for the introduction of mandatory fortification in South Africa. © The Authors 2005.Conference Pape
Fast Ion Charge Exchange Spectroscopy Measurement Using Radially Injected Neutral Beam on Large Helical Device
Microbiome profiling by Illumina sequencing of combinatorial sequence-tagged PCR products
We developed a low-cost, high-throughput microbiome profiling method that
uses combinatorial sequence tags attached to PCR primers that amplify the rRNA
V6 region. Amplified PCR products are sequenced using an Illumina paired-end
protocol to generate millions of overlapping reads. Combinatorial sequence
tagging can be used to examine hundreds of samples with far fewer primers than
is required when sequence tags are incorporated at only a single end. The
number of reads generated permitted saturating or near-saturating analysis of
samples of the vaginal microbiome. The large number of reads al- lowed an
in-depth analysis of errors, and we found that PCR-induced errors composed the
vast majority of non-organism derived species variants, an ob- servation that
has significant implications for sequence clustering of similar high-throughput
data. We show that the short reads are sufficient to assign organisms to the
genus or species level in most cases. We suggest that this method will be
useful for the deep sequencing of any short nucleotide region that is
taxonomically informative; these include the V3, V5 regions of the bac- terial
16S rRNA genes and the eukaryotic V9 region that is gaining popularity for
sampling protist diversity.Comment: 28 pages, 13 figure
Being well, being musical: Music composition as a resource and occupation for older people
Introduction: Participatory music making for older people has tended to focus on singing and performance. In a community music project undertaken by Manchester Camerata (a chamber orchestra), Blacon Community Trust and a small group of older adults, participants were given the opportunity to compose individual pieces of music interactively with professional musicians. This paper reports the findings of the research project. Method: An arts-based research method was adopted and incorporated action research and interpretive interactionism to articulate the experiences and perceptions of participants. Participants and Manchester Camerata musicians also worked together to represent the thematic findings of the research in a group composition. Findings: The findings demonstrate that individual and group music composition contributed to a sense of wellbeing through control over musical materials, opportunities for creativity and identity making, validation of life experience and social engagement with other participants and professional musicians. Conclusion; The results emphasised occupation as essential to health and wellbeing in the later stages of life. The findings also highlight the particularly innovative aspects of this research: (i) the use of music composition as a viable arts-in-health occupation for older people and (ii) the arts-based research method of group composition. (PsycINFO Database Record (c) 2016 APA, all rights reserved
The Occupational Wellbeing of People Experiencing Homelessness
This paper reports findings of a study that utilised an occupational perspective to explore how wellbeing was achieved and sustained by the occupations of people experiencing homelessness in Australia. Thirty three in-depth qualitative interviews were conducted with homeless individuals in a regional city in Australia. Data from the interviews were thematically analysed to understand the relationship between wellbeing, as defined by the individual, and the occupations engaged in by people experiencing homelessness. The findings are reported here as three collective narratives that illustrate the experiences of diverse groups within the homelessness population explored in this study. The study demonstrates how occupations go beyond the individual experience and choice; to explore the social and cultural value of occupations as a means to wellbeing. The findings are discussed in relation to three key themes that emerged from the study: survival, self-identity and social connectedness. These three interconnected concepts complement the existing occupational science literature, and offer a preliminary framework for understanding and improving wellbeing for disadvantaged and marginalised people where occupations are restricted by societal forces. The findings support the urgent need to redirect services to support occupational opportunities that are socially and culturally valued and enhance survival, self-identity and connectedness of homeless people
- …
