Bars and Cold Dark Matter Halos

The central part of a dark matter halo reacts to the presence and evolution of a bar. Not only does the halo absorb angular momentum from the disk, it can also be compressed and have its shape modified. We study these issues in a series of cosmologically motivated, highly resolved N-body simulations of barred galaxies run under different initial conditions. In all models we find that the inner halo's central density increases. We model this density increase using the standard adiabatic approximation and the modified formula by Gnedin et al. and find that halo mass profiles are better reproduced by this latter. In models with a strong bar, the dark matter in the central region forms a bar-like structure (``dark matter bar''), which rotates together with the normal bar formed by the stellar component (``stellar bar''). The minor-to-major axial ratio of a halo bar changes with radius with a typical value 0.7 in the central disk region. DM bar amplitude is mostly a function of the stellar bar strength. Models in which the bar amplitude increases or stays roughly constant with time, initially large (40%-60%) misalignment between the halo and disk bars quickly decreases with time as the bar grows. The halo bar is nearly aligned with the stellar bar (~10 degrees lag for the halo) after ~2 Gyr. The torque, which the halo bar exerts on the stellar bar, can serve as a mechanism to regulate the angular momentum transfer from the disk to the halo.Comment: Modified version after referee's suggestions. 17 pages, 12 figures, accepted by Ap

Incidence of seropositive myasthenia gravis in Cape Town and South Africa

Background. Myasthenia gravis (MG) is a treatable autoimmune disease characterised by fatiguable weakness of skeletal muscles. More than 85% of MG patients have antibodies to the acetylcholine receptor (AChR) at the neuromuscular junction or are seropositive for MG (SPMG). In the developed world the incidence of MG has increased, particularly among older individuals, but no epidemiological studies have been done on SPMG in Africa. Objectives. To determine the annual incidence rate (IR) of SPMG in the Cape Town (CT) municipality, and the crude annual IR of SPMG for the whole of South Africa (SA). Methods. Positive AChR antibody tests were identified between 1 January 2003 and 1 January 2005 for patients living in CT, and the age- and sex-specific incidences were calculated. To determine the national crude annual IR over the same period, positive assays were identified from the laboratories that process AChR assays for SA. National Census 2001 population statistics formed the denominators. Results. There were 65 positive assays in CT, and 230 nationwide. Based on these figures the annual IR for CT was 11.2 per million per year (95% confidence interval (CI) 8.7 - 14.3), and for South Africa 2.6 per million / year (95% CI 2.2 - 2.9). After a questionnaire response from CT neurologists regarding the routine use of the AChR antibody assay, the annual IR for CT was adjusted to 12.6 per million (95% CI 9.9 - 15.9) to incorporate those presumed to have SPMG without a confirmatory test. In CT, the IR in females was 15.3 per million / year (95% CI 11.2 - 20.4), and in males, 6.8 per million / year (95% CI 4.1 - 10.7). The CT IRs for blacks, coloureds and whites were not statistically different after adjusting for age and gender. The IR of SPMG in CT was 6 times greater in those presenting after the age of 50 years than in those with earlier disease onset (95% CI 3.7 - 9.7). Conclusions. The annual IR of SPMG in CT is much the same as rates recorded recently in other developed countries, but the rest of SA has a much lower IR. A preponderance of MG starting after the age of 50 years reflects a worldwide trend, although the CT data showed a relatively lower-than-expected incidence for older males. IRs for SPMG vary widely in different regions in SA; this is likely to be related to differences in regional health care delivery, and underdiagnosis

Using stochastic acceleration to place experimental limits on the charge of antihydrogen

Assuming hydrogen is charge neutral, CPT invariance demands that antihydrogen also be charge neutral. Quantum anomaly cancellation also demands that antihydrogen be charge neutral. Standard techniques based on measurements of macroscopic quantities of atoms cannot be used to measure the charge of antihydrogen. In this paper, we describe how the application of randomly oscillating electric fields to a sample of trapped antihydrogen atoms, a form of stochastic acceleration, can be used to place experimental limits on this charge

Environmental support for outdoor activities and older people’s Quality of Life

Information unavailable on Web of Knowledge and PubMed

Relationship between environmental exposure to pesticides and anthropometric outcomes of boys in the rural Western Cape, South Africa

BACKGROUND: Rural residents in the Western Cape (WC), South Africa (SA) are highly exposed to agricultural pesticides that could impact their reproductive development. However, epidemiological evidence of the effect of pesticides on pubertal growth is contradictory. OBJECTIVE: To investigate the effect of pesticide exposure measured using indices of environmental exposure to pesticides on the pubertal growth of boys in rural WC, SA. METHODS: A cross-sectional study of 269 boys (177 of whom gave a history of residing on farms) was conducted. A questionnaire was administered, height and weight were measured and body mass index was calculated. A proximity index (PI) and spraying index (SI) was developed, measuring the lifetime average home distance from pesticide spraying and average frequency of spraying pesticides on a farm, respectively. RESULTS: Median age of boys was 12.4 years (interquartile range 9.5 - 13.3). More than 60% boys had height and weight <50th percentile for age. After adjusting for confounders, PI was significantly associated with shorter stature and lower weight (-1.7 cm/10-fold decrease, p=0.02 and -1.24 kg/10-fold decrease, p=0.04; respectively) and SI was non-significantly associated (-1.4 cm/10-fold increase, p=0.05 and -1.1 cm/10-fold increase, p=0.06; respectively). Associations were stronger for boys aged <11 years and were weaker when excluding non- farm boys. There were no other associations between outcome and exposure. CONCLUSIONS: The use of quantitative exposure indices showed that lower heights and weights might be associated with pesticide exposure in farm boys v. non-farm boys, but not among farm boys. Lower anthropometric measurements among farm boys v. non-farm boys appear stronger at a younger age. The indices of environmental exposure to pesticides require further development

Eyewear for rugby union: wearer characteristics and experience with rugby goggles

YesUnlike many other sports, Rugby Union has not permitted players to wear spectacles or eye protection. With an industrial partner, World Rugby developed goggles suitable for use while playing rugby for the purposes of growing participation amongst those that need to wear corrective lenses. This study reports on the profile and experiences of goggle wearers. 387 players received the goggles. Data were obtained from 188 (49 %) using an online, 75-item questionnaire. 87 % “strongly agreed/agreed” that goggles are beneficial and 75 % are happy with goggle performance. Common problems reported by 49.7 and 32.6 % of respondents were issues with fogging-up and getting dirty. 15 (8 %) players stopped wearing the goggles because of fogging-up, limits to peripheral vision and poor comfort/fit. Injuries were reported in 3 % of respondents. In none of these cases did the player stop wearing the goggles. From the positive experience of players in the trial, the goggles were adopted into the Laws of the game on July 1, 2019. As the need to correct vision with spectacles is common, and contact lenses are not worn by 80 % + of spectacle wearers, the new Rugby goggles will widen participation for those that need to wear refractive correction, or have an existing/increased risk of uniocular visual impairment

Need for timely paediatric HIV treatment within primary health care in rural South Africa

&lt;p&gt;Background: In areas where adult HIV prevalence has reached hyperendemic levels, many infants remain at risk of acquiring HIV infection. Timely access to care and treatment for HIV-infected infants and young children remains an important challenge. We explore the extent to which public sector roll-out has met the estimated need for paediatric treatment in a rural South African setting.&lt;/p&gt; &lt;p&gt;Methods: Local facility and population-based data were used to compare the number of HIV infected children accessing HAART before 2008, with estimates of those in need of treatment from a deterministic modeling approach. The impact of programmatic improvements on estimated numbers of children in need of treatment was assessed in sensitivity analyses.&lt;/p&gt; &lt;p&gt;Findings: In the primary health care programme of HIV treatment 346 children &#60;16 years of age initiated HAART by 2008; 245(70.8%) were aged 10 years or younger, and only 2(&#60;1%) under one year of age. Deterministic modeling predicted 2,561 HIV infected children aged 10 or younger to be alive within the area, of whom at least 521(20.3%) would have required immediate treatment. Were extended PMTCT uptake to reach 100% coverage, the annual number of infected infants could be reduced by 49.2%.&lt;/p&gt; &lt;p&gt;Conclusion: Despite progress in delivering decentralized HIV services to a rural sub-district in South Africa, substantial unmet need for treatment remains. In a local setting, very few children were initiated on treatment under 1 year of age and steps have now been taken to successfully improve early diagnosis and referral of infected infants.&lt;/p&gt

Dynamical Friction and the Distribution of Dark Matter in Barred Galaxies

We use fully self-consistent N-body simulations of barred galaxies to show that dynamical friction from a dense dark matter halo dramatically slows the rotation rate of bars. Our result supports previous theoretical predictions for a bar rotating within a massive halo. On the other hand, low density halos, such as those required for maximum disks, allow the bar to continue to rotate at a high rate. There is somewhat meager observational evidence indicating that bars in real galaxies do rotate rapidly and we use our result to argue that dark matter halos must have a low central density in all high surface brightness disk galaxies, including the Milky Way. Bars in galaxies that have larger fractions of dark matter should rotate slowly, and we suggest that a promising place to look for such candidate objects is among galaxies of intermediate surface brightness.Comment: 6 pages, Latex, 3 figures, Accepted by Ap.J.L., revised copy, includes an added paragrap

Creative Little Scientists: enabling creativity through science and mathematics in preschool and first years of primary education: guidelines and curricula for teacher training (D5.2)

One of the key objectives of the Creative Little Scientists project is to propose a set of curriculum design principles as guidelines for European initial teacher education (ITE) and continuous professional development (CPD) programmes that will foster creative approaches to science and mathematics learning in preschool and the first years of primary education in the frame of inquiry-based educational environments. Work Package 5 is based on the findings of the theoretical review (Work Package 2), comparative studies (Work Package 3), and in-depth field research (Work Package 4). In addition it has been informed by the involvement of communities of stakeholders – teachers, student teachers, school staff members, teacher educators, researchers, out-of-the box thinkers, policy makers and experts in the field of inquiry, creativity or science – in online and face-to-face focus groups. This document offers teacher education policy makers and institutions a set of curriculum design principles and accompanying conceptual recommendations in order to design and apply curricula that will foster creative approaches to science and mathematics learning in preschool and first years of primary education. Furthermore it offers teacher education institutions a related set of teacher outcomes about what teachers should know and be able to do in order to develop such creative approaches. These can be seen as concrete recommendations for teacher educators and teacher education institutions to frame their sessions, workshops and courses. They are directly linked to the implications for teacher training which arose from deliverables D2.2 Conceptual Framework, D3.2 Report on Mapping and Comparing Recorded Practices, D3.3 Report on First Survey of School Practice and D4.4 Report on Practices and their Implications (see also Figure below)

Creative Little Scientists: enabling creativity through science and mathematics in preschool and first years of primary education: exemplary teacher training materials (D5.3)

This report focuses on the Exemplary Teacher Training Materials. The aim of these materials is to illustrate the teacher education Curriculum Design Principles and related Teacher Outcomes, which were developed during Work Package 5 as part of D5.2 Guidelines and Curricula for Teacher Training and can also be found in this report. They are designed for teacher educators to use in Initial Teacher Education (ITE) and teacher Continuing Professional Development (CPD). They aim to extend professional understanding and enhance professional development in order to foster creativity in science and mathematics education in the early years. This report explains the methodology used to develop the materials, the nature and structure of the materials and includes suggestions for their use in all phases of teacher education. Methodology used to develop the exemplary teacher training materials In the Creative Little Scientists project, the comparative research and the in-depth fieldwork in particular identified significant issues that need to be tackled in teacher education in order to foster creativity in science and mathematics education in the early years. Based on these issues the teacher education Content Design Principles, created during the curriculum design research, were refined, and a set of Teacher Outcomes developed. To produce the Exemplary Teacher Training Materials, classroom examples of creative learning and teaching were selected using these Content Design Principles and related Teacher Outcomes. All partners re-visited their data from the in-depth fieldwork (Work Package 4) to select pertinent images, interviews or classroom extracts that evidenced one or more of the Teacher Outcomes. To support and record the selection process a grid was provided where partners could record links between the fieldwork data selected, Teacher Outcomes and factors associated with creativity in learning and teaching in science and mathematics. Templates were then used to structure the classroom materials and provide consistent information about the contexts from which they were drawn. Teacher training materials: an overview and how to use them In total 169 templates are available containing exemplary materials from fieldwork for use in teacher education. These are structured in an Excel-file and can be found on the website http://www.creative-little-scientists.eu. In order to support the full use of this diverse range of resources for teacher training, suggestions are provided in this report of selection and use of these exemplary materials in relation to particular themes and associated Content Design Principles as follows: o Suggestion 1: Use of questions and ideas of children by teachers (Principles 10 and 11) o Suggestion 2: Resources and learning environment as essential context factors for Creativity and Inquiry (Principles 10, 14, 17) o Suggestion 3: Focus on the nature of science – a link with creativity (Principle 3) o Suggestion 4: Focus on Inquiry Based Science Education – link with creativity (Principle 6) o Suggestion 5: Focus on Practical Investigations which foster creativity (Principles 2, 17) o Suggestion 6: Collaboration/group work in inquiry and creativity based approaches (Principle 15) o Suggestion 7: The role of play in inquiry and creativity based approaches (Principles 7, 8, 17) o Suggestion 8: The use of the various modes of expression and representation of science and mathematics learning to support inquiry and the development of creativity – link with assessment (Principles 7, 9) o Suggestion 9: The role of the teacher in Inquiry and Creativity approaches (Principles 1, 7, 11) o Suggestion 10: Cross curricular project work to foster inquiry and creativity (Principle 6) The suggestions above are carefully chosen since they encourage inquiry and creativity in science and mathematics education for early years, by focusing on the synergies between Inquiry-Based Science Education (IBSE) and Creative Approaches (CA): play and exploration; motivation and affect; dialogue and collaboration; problem solving and agency; questioning and curiosity; reflection and reasoning; teacher scaffolding and involvement; and assessment for learning. As noted in the Conceptual Framework (D2.2) and experienced during the in-depth fieldwork, developing contexts for inquiry and exploration which foster creative learning, and achieving a balance between teacher intervention and children collaboration, as well as teacher standing back and learner agency, represent considerable professional challenges. The provided exemplary teacher training materials and associated suggestions for their use help address these challenges