The impact of pollution on stellar evolution models

An approach is introduced for incorporating the concept of stellar pollution into stellar evolution models. The approach involves enhancing the metal content of the surface layers of stellar models. In addition, the surface layers of stars in the mass range of 0.5-2.0 Solar masses are mixed to an artificial depth motivated by observations of lithium abundance. The behavior of polluted stellar evolution models is explored assuming the pollution occurs after the star has left the fully convective pre main sequence phase. Stellar models polluted with a few Earth masses of iron are significantly hotter than stars of the same mass with an equivalent bulk metallicity. Polluted stellar evolution models can successfully reproduce the metal-rich, parent star tau Bootis and suggest a slightly lower mass than standard evolution models. Finally, the possibility that stars in the Hyades open cluster have accreted an average of 0.5 Earth masses of iron is explored. The results indicate that it is not possible to rule out stellar pollution on this scale from the scatter of Hyades stars on a color-magnitude diagram. The small amount of scatter in the observational data set does rule out pollution on the order of 1.5 Earth masses of iron. Pollution effects at the low level of 0.5 Earth masses of iron do not produce substantial changes in a star's evolution.Comment: 14 pages, 3 figures, AASTeX, to appear in the 10/10/03 issue of Ap

Obesity prevention in early life: An opportunity to better support the role of Maternal and Child Health Nurses in Australia

© 2015 Laws et al.; licensee BioMed Central. Background: Because parents with young children access primary health care services frequently, a key opportunity arises for Maternal and Child Health (MCH) nurses to actively work with families to support healthy infant feeding practices and lifestyle behaviours. However, little is known regarding the extent to which MCH nurses promote obesity prevention practices and how such practices could be better supported. Methods: This mixed methods study involved a survey of 56 MCH nurses (response rate 84.8%), 16 of whom participated in semi-structured qualitative interviews. Both components aimed to examine the extent to which nurses addressed healthy infant feeding practices, healthy eating, active play and limiting sedentary behavior during routine consultations with young children 0-5 years. Key factors influencing such practices and how they could be best supported were also investigated. All data were collected from September to December 2013. Survey data were analysed descriptively and triangulated with qualitative interview findings, the analysis of which was guided by grounded theory principles. Results: Although nurses reported measuring height/length and weight in most consultations, almost one quarter (22.2 %) reported never/rarely using growth charts to identify infants or children at risk of overweight or obesity. This reflected a reluctance to raise the issue of weight with parents and a lack of confidence in how to address it. The majority of nurses reported providing advice on aspects of infant feeding relevant to obesity prevention at most consultations, with around a third (37 %) routinely provided advice on formula preparation. Less than half of nurses routinely promoted active play and only 30 % discussed limiting sedentary behaviour such as TV viewing. Concerns about parental receptiveness and maintaining rapport were key barriers to more effective implementation. Conclusion: While MCH nurses are well placed to address obesity prevention in early life, there is currently a missed public health opportunity. Improving nurse skills in behaviour change counseling will be key to increasing their confidence in raising sensitive lifestyle issues with parents to better integrate obesity prevention practices into normal MCH service delivery

Blogging in the physics classroom: A research-based approach to shaping students' attitudes towards physics

Even though there has been a tremendous amount of research done in how to help students learn physics, students are still coming away missing a crucial piece of the puzzle: why bother with physics? Students learn fundamental laws and how to calculate, but come out of a general physics course without a deep understanding of how physics has transformed the world around them. In other words, they get the "how" but not the "why". Studies have shown that students leave introductory physics courses almost universally with decreased expectations and with a more negative attitude. This paper will detail an experiment to address this problem: a course weblog or "blog" which discusses real-world applications of physics and engages students in discussion and thinking outside of class. Specifically, students' attitudes towards the value of physics and its applicability to the real-world were probed using a 26-question Likert scale survey over the course of four semesters in an introductory physics course at a comprehensive Jesuit university. We found that students who did not participate in the blog study generally exhibited a deterioration in attitude towards physics as seen previously. However, students who read, commented, and were involved with the blog maintained their initially positive attitudes towards physics. Student response to the blog was overwhelmingly positive, with students claiming that the blog made the things we studied in the classroom come alive for them and seem much more relevant.Comment: 20 pages, 6 figure

Parent Stars of Extrasolar Planets. X. Lithium Abundances and vsini Revisited

We determine Li abundances and vsini values from new spectra of 53 stars with Doppler-detected planets not included in our previous papers in this series. We also examine two sets of stars without detected planets, which together serve as our comparison sample. Using the method of comparison of Li abundances and vsini values between two sets of stars we introduced in Gonzalez (2008), we confirm that these two quantities are smaller among stars with planets compared to stars without detected planets near the solar temperature. The transition from low to high Li abundance among SWPs occurs near 5850 K, a revision of about 50 K from our previous determination. The transition from low to high vsini occurs near 6000 K, but this temperature is not as well constrained.Comment: accepted for publication in MNRAS; 14 pages, 13 figures, 3 table

Is there scope for community health nurses to address lifestyle risk factors? The community nursing SNAP trial

Background: This paper examines the opportunity and need for lifestyle interventions for patients attending generalist community nursing services in Australia. This will help determine the scope for risk factor management within community health care by generalist community nurses (GCNs). Methods: This was a quasi-experimental study conducted in four generalist community nursing services in NSW, Australia. Prior to service contacts, clients were offered a computer-assisted telephone interview to collect baseline data on socio-demographics, health conditions, smoking status, physical activity levels, alcohol consumption, height and weight, fruit and vegetable intake and \u27readiness-to-change\u27 for lifestyle risk factors. Results: 804 clients participated (a response rate of 34.1%). Participants had higher rates of obesity (40.5% vs 32.1%) and higher prevalence of multiple risk factors (40.4% vs 29.5%) than in the general population. Few with a SNAPW (S moking-N utrition-A lcohol-P hysical-Activity-Weight) risk factor had received advice or referral in the previous 3 months. The proportion of clients identified as at risk and who were open to change (i.e. contemplative, in preparation or in action phase) were 65.0% for obese/overweight; 73.8% for smokers; 48.2% for individuals with high alcohol intake; 83.5% for the physically inactive and 59.0% for those with poor nutrition. Conclusions: There was high prevalence of lifestyle risk factors. Although most were ready to change, few clients recalled having received any recent lifestyle advice. This suggests that there is considerable scope for intervention by GCNs. The results of this trial will shed light on how best to implement the lifestyle risk factor management in routine practice

Concepts of mental disorders in the United Kingdom : Similarities and differences between the lay public and psychiatrists

BACKGROUND: The lay public often conceptualise mental disorders in a different way to mental health professionals, and this can negatively impact on outcomes when in treatment. AIMS: This study explored which disorders the lay public are familiar with, which theoretical models they understand, which they endorse and how they compared to a sample of psychiatrists. METHODS: The Maudsley Attitude Questionnaire (MAQ), typically used to assess mental health professional's concepts of mental disorders, was adapted for use by a lay community sample (N = 160). The results were compared with a sample of psychiatrists (N = 76). RESULTS: The MAQ appeared to be accessible to the lay public, providing some interesting preliminary findings: in order, the lay sample reported having the best understanding of depression followed by generalised anxiety, schizophrenia and finally antisocial personality disorder. They best understood spiritualist, nihilist and social realist theoretical models of these disorders, but were most likely to endorse biological, behavioural and cognitive models. The lay public were significantly more likely to endorse some models for certain disorders suggesting a nuanced understanding of the cause and likely cure, of various disorders. Ratings often differed significantly from the sample of psychiatrists who were relatively steadfast in their endorsement of the biological model. CONCLUSION: The adapted MAQ appeared accessible to the lay sample. Results suggest that the lay public are generally aligned with evidence-driven concepts of common disorders, but may not always understand or agree with how mental health professionals conceptualise them. The possible causes of these differences, future avenues for research and the implications for more collaborative, patient-clinician conceptualisations are discussed.Peer reviewedFinal Accepted Versio

Stochastic dynamics of Francisella tularensis infection and replication

We study the pathogenesis of Francisella tularensis infection with an experimental mouse model, agent-based computation and mathematical analysis. Following inhalational exposure to Francisella tularensis SCHU S4, a small initial number of bacteria enter lung host cells and proliferate inside them, eventually destroying the host cell and releasing numerous copies that infect other cells. Our analysis of disease progression is based on a stochastic model of a population of infectious agents inside one host cell, extending the birth-and-death process by the occurrence of catastrophes: cell rupture events that affect all bacteria in a cell simultaneously. Closed expressions are obtained for the survival function of an infected cell, the number of bacteria released as a function of time after infection, and the total bacterial load. We compare our mathematical analysis with the results of agent-based computation and, making use of approximate Bayesian statistical inference, with experimental measurements carried out after murine aerosol infection with the virulent SCHU S4 strain of the bacterium Francisella tularensis, that infects alveolar macrophages. The posterior distribution of the rate of replication of intracellular bacteria is consistent with the estimate that the time between rounds of bacterial division is less than 6 hours in vivo

The impact of interventions to prevent obesity or improve obesity related behaviours in children (0-5 years) from socioeconomically disadvantaged and/or indigenous families: A systematic review

© 2014 Laws et al.; licensee BioMed Central Ltd. Background: Children from disadvantaged families including those from low socioeconomic backgrounds and Indigenous families have higher rates of obesity, making early intervention a priority. The aim of this study was to systematically review the literature to examine the effectiveness of interventions to prevent obesity or improve obesity related behaviours in children 0-5 years from socioeconomically disadvantaged or Indigenous families. Methods. Searches of major electronic databases identified articles published from 1993-2013 targeting feeding practices, anthropometric, diet, activity or sedentary behaviour outcomes. This was supplemented with snowballing from existing reviews and primary studies. Data extraction was undertaken by one author and cross checked by another. Quality assessments included both internal and external validity. Results: Thirty-two studies were identified, with only two (both low quality) in Indigenous groups. Fourteen studies had a primary aim to prevent obesity. Mean differences between intervention and control groups ranged from -0.29 kg/m2to -0.54 kg/m2for body mass index (BMI) and -2.9 to -25.6% for the prevalence of overweight/obesity. Interventions initiated in infancy (under two years) had a positive impact on obesity related behaviours (e.g. diet quality) but few measured the longer-term impact on healthy weight gain. Findings amongst pre-schoolers (3-5 years) were mixed, with the more successful interventions requiring high levels of parental engagement, use of behaviour change techniques, a focus on skill building and links to community resources. Less than 10% of studies were high quality. Future studies should focus on improving study quality, including follow-up of longer-term anthropometric outcomes, assessments of cost effectiveness, acceptability in target populations and potential for implementation in routine service delivery. Conclusion: There is an urgent need for further research on effective obesity prevention interventions for Indigenous children. The findings from the growing body of intervention research focusing on obesity prevention amongst young children from socioeconomically disadvantaged families suggest intervention effects are modest but promising. Further high quality studies with longer term follow up are required. Trial registration. PROSPERO Registration no: CRD42013006536

Integrated stratigraphy of the Waitakian-Otaian Stage boundary stratotype, Early Miocene, New Zealand

The base of the type section of the Otaian Stage at Bluecliffs, South Canterbury, is recognised as the stratotype for the boundary between the Waitakian and Otaian Stages. Principal problems with the boundary are the restriction of existing bioevent proxies to shelf and upper slope environments and its uncertain age. These topics are addressed by a multidisplinary study of a 125 m section about the boundary, which examines its lithostratigraphy, depositional setting, biostratigraphy, correlation, and geochronology. The lower siltstone lithofacies (0-38.5 m) was deposited at upper bathyal depths (200-600 m) in a marginal basin which was partially sheltered from fully oceanic circulation by a submarine high and islands. The site was covered by cool-temperate water and was probably adjacent to the Subtropical Convergence. This unit is succeeded by the banded lithofacies (38.5-106 m) and the upper siltstone lithofacies (basal 19 m studied). Paleodepth probably declined up-sequence, but deposition at shelf depths is not definitely indicated. A cyclic pattern of abundance spikes in benthic and planktonic foraminifera commences 9 m above base and extends to 73 m in the banded lithofacies. Oxygen isotope excursions (up to 2.08%) in Euuvigerina miozea and Cibicides novozelandicus are greatest within the interval containing the abundance spikes. The stage boundary occurs in the banded lithofacies at the highest abundance spike (73 m). Although condensed intervals might affect the completeness of the section, they are not associated with sedimentary discontinuities, and we consider that the section is suitable as a biostratigraphic reference. Spores, pollens, dinoflagellates, calcareous nannofossils, foraminifera, bryozoans, and ostracods are preserved near the boundary, but molluscs principally occur higher, in the shallower upper siltstone lithofacies. Siliceous microfossils are rare. There is considerable scope for further biostratigraphic research. The primary event marking the boundary at 73 m is the appearance of the benthic foraminifer Ehrenbergina marwicki. This is a distinctive and widely distributed event but is restricted to shelf and upper bathyal environments. Supplementary events in planktonic foraminifera and calcareous nannofossils were researched. Highest occurrences of Globigerina brazieri and G. euapertura are recorded at 47 and 58 m. There is a marked decline in relative abundance of Paragloborotalia spp. at 62 m. Helicosphaera carteri becomes more abundant than H. euphratis between 56 and 87 m. These events are not exact proxies for the boundary but they may usefully indicate proximity to it. They occur in the interval of prominent spikes in foraminiferal abundance. The Waitakian-Otaian boundary is dated at 21.7 Ma by strontium isotopes. Stable primary remanence could not be determined in a pilot paleomagnetic study of Bluecliffs specimens. However, specimens trended towards reversed polarity, and remagnetisation great circle analysis will allow directions to be calculated in future collections

Are beryllium abundances anomalous in stars with giant planets?

In this paper we present beryllium (Be) abundances in a large sample of 41 extra-solar planet host stars, and for 29 stars without any known planetary-mass companion, spanning a large range of effective temperatures. The Be abundances were derived through spectral synthesis done in standard Local Thermodynamic Equilibrium, using spectra obtained with various instruments. The results seem to confirm that overall, planet-host stars have ``normal'' Be abundances, although a small, but not significant, difference might be present. This result is discussed, and we show that this difference is probably not due to any stellar ``pollution'' events. In other words, our results support the idea that the high-metal content of planet-host stars has, overall, a ``primordial'' origin. However, we also find a small subset of planet-host late-F and early-G dwarfs that might have higher than average Be abundances. The reason for the offset is not clear, and might be related either to the engulfment of planetary material, to galactic chemical evolution effects, or to stellar-mass differences for stars of similar temperature.Comment: 15 pages, 9 figures, accepted for publication in Astronomy & Astrophysic