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

A critique of narrative reviews of the evidence-base for ECT in depression

© The Author(s), 2022. Published by Cambridge University Press. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/)There has been recent debate regarding the efficacy of electroconvulsive therapy in the treatment of depression. This has been based on narrative reviews that contradict existing systematic reviews and meta-analyses. In this special article, we highlight the mistakes that occur when interpreting evidence using narrative reviews, as opposed to conventional systematic reviews and meta-analyses.Peer reviewedFinal Published versio

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

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

Promoting healthy weight for all young children: a mixed methods study of child and family health nurses' perceptions of barriers and how to overcome them.

Background:Childhood obesity is a global health concern. Early intervention to help parents adopt best practice for infant feeding and physical activity is critical for maintaining healthy weight. Australian governments provide universal free primary healthcare from child and family health nurses (CFHNs) to support families with children aged up to five years and to provide evidence-based advice to parents. This paper aims to examine factors influencing the child obesity prevention practices of CFHNs and to identify opportunities to support them in promoting healthy infant growth. Methods:This mixed methods study used a survey (n = 90) and semi-structured interviews (n = 20) with CFHNs working in two local health districts in Sydney, Australia. Survey data were analysed descriptively; interview transcripts were coded and analysed iteratively. Survey and interview questions examined how CFHNs addressed healthy infant feeding practices, healthy eating, active play and limiting sedentary behaviour during routine consultations; factors influencing such practices; and how CFHNs could be best supported. Results:CFHNs frequently advised parents on breastfeeding, introducing solid foods, and techniques for settling infants. They spent less time providing advice on evidence-based formula feeding practices or encouraging physical activity in young children. Although nurses frequently weighed and measured children, they did not always use growth charts to identify those at risk of becoming overweight or obese. Nurses identified several barriers to promoting healthy weight gain in infants and young children, including limited parental recognition of overweight in their children or motivation to change diet or lifestyle; socioeconomic factors (such as the cost of healthy food); and beliefs and attitudes about infant weight and the importance of breastfeeding and physical activity amongst parents and family members. Conclusions:CFHNs require further education and support for their role in promoting optimal child growth and development, especially training in behaviour change techniques to increase parents' understanding of healthy infant weight gain. Parent information resources should be accessible and address cultural diversity. Resources should highlight the health effects of childhood overweight and obesity and emphasise the benefits of breastfeeding, appropriate formula feeding, suitable first foods, responsiveness to infant feeding cues, active play and limiting screen time

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

Cymantrene–Triazole "Click" Products: Structural Characterization and Electrochemical Properties

We report the first known examples of triazole-derivatized cymantrene complexes (η5-[4-substituted triazol-1-yl]cyclopentadienyl)tricarbonylmanganese(I), obtained via a “click” chemical synthesis, bearing a phenyl, 3-aminophenyl, or 4-aminophenyl moiety at the 4-position of the triazole ring. Structural characterization data using multinuclear NMR, UV–vis, ATR-IR, and mass spectrometric methods are provided, as well as crystallographic data for (η5-[4-phenyltriazol-1-yl]cyclopentadienyl)tricarbonylmanganese(I) and (η5-[4-(3-aminophenyl)triazol-1-yl]cyclopentadienyl)tricarbonylmanganese(I). Cyclic voltammetric characterization of the redox behavior of each of the three cymantrene–triazole complexes is presented together with digital simulations, in situ infrared spectroelectrochemistry, and DFT calculations to extract the associated kinetic and thermodynamic parameters. The trypanocidal activity of each cymantrene–triazole complex is also examined, and these complexes are found to be more active than cymantrene alone

Orthographic facilitation in oral vocabulary acquisition

An experiment investigated whether exposure to orthography facilitates oral vocabulary learning. A total of 58 typically developing children aged 8-9 years were taught 12 nonwords. Children were trained to associate novel phonological forms with pictures of novel objects. Pictures were used as referents to represent novel word meanings. For half of the nonwords children were additionally exposed to orthography, although they were not alerted to its presence, nor were they instructed to use it. After this training phase a nonword-picture matching posttest was used to assess learning of nonword meaning, and a spelling posttest was used to assess learning of nonword orthography. Children showed robust learning for novel spelling patterns after incidental exposure to orthography. Further, we observed stronger learning for nonword-referent pairings trained with orthography. The degree of orthographic facilitation observed in posttests was related to children's reading levels, with more advanced readers showing more benefit from the presence of orthography

How well do police specialists risk assess Registered Sexual Offenders?

This study examined 91 Active Risk Management System (ARMS) assessments from four police areas across England and Wales. ARMS is a tool that guides criminal justice practitioners to assess and develop formal risk management plans based on the risks and strengths of individual clients convicted of sexual offending. This present study is particularly concerned with the application of this new tool and the quality of subsequent risk assessment as a result of police practitioner assessment. Findings indicate the quality of ARMS assessments were not to the expected standard. The study found while there were acceptable levels of detail and evidence documented by practitioners across individual areas; overall, assessor risk ratings and risk management plans were poor. This paper provides an outline of these findings, making suggestions for areas of improvement, along with recommendations for policy, practice, and research