The Li Overabundance of J37: Diffusion or Accretion?

In September 2002 the discovery of a super Li-rich F-dwarf (J37) in NGC 6633, an iron poor analogue of the better studied Hyades and Praecepe open clusters, was announced. This unique star was thought to be the smoking gun for the action of diffusion, models of which predict a narrow "Li-peak" at approximately the correct temperature. However, with more detailed studies into J37s abundance pattern this star provides firm evidence for the accretion of planetesimals or other material from the circumstellar environment of new born stars. Thanks to the specific predictions made about the behaviour of Be abundances, (the most striking of which being no Be in super-Li-rich dwarfs subject to diffusion) the opposing diffusion/accretion predictions can be tested. Initial modelling of the Be line indicates that J37 is as Be rich as it is Li rich; log N(Be) = 2.25 +/- 0.25, and so is broadly consistent with an accretion-fuelled enhancement. However, that both Li and Be are enhanced by much more than the iron-peak elements (as determined in previous studies) suggests that diffusion also plays a role in increasing the abundances of Li and Be specifically. Furthermore, a new data set from the UVES/UT2 combination has allowed the elemental abundance of Iron to be measured, and the set of preliminary stellar parameters determined; Teff ~ 7340 K, log g ~ 4.1, microturbulence ~ 4.3 km/s, [Fe/H] ~ 0.50. This again provides distinct evidence for the effects of accretion in J37 and requires a new synthesis of the Be doublet.Comment: 5 pages, 2 figures. Poster presented at IAU Symposium 224 "The A Star Puzzle", 7-13 July 2004, Poprad, Slovaki

Beryllium Enhancement as Evidence for Accretion in a Lithium-Rich F Dwarf

The early F dwarf star ``J37'' in the open cluster NGC6633 shows an unusual pattern of photospheric abundances, including an order of magnitude enhancement of lithium and iron-peak elements, but an under-abundance of carbon. As a consequence of its thin convection zone these anomalies have been attributed to either radiative diffusion or the accretion of hydrogen-depleted material. By comparing high resolution VLT/UVES spectra of J37 (and other F stars in NGC 6633) with syntheses of the Be ii doublet region at 3131 Ang, we establish that J37 also has a Be abundance (A(Be)=3.0+/-0.5) that is at least ten times the cosmic value. This contradicts radiative diffusion models that produce a Li over-abundance, as they also predict photospheric Be depletion. Instead, since Be is a highly refractory element, it supports the notion that J37 is the first clear example of a star that has accreted volatile-depleted material with a composition similar to chondritic meteorites, although some diffusion may be necessary to explain the low C and O abundances.Comment: Accepted for publication in MNRAS letters, 5 page

Optical second harmonic generation probe of two-dimensional ferroelectricity

Optical second harmonic generation (SHG) is used as a noninvasive probe of two-dimensional (2D) ferroelectricity in Langmuir-Blodgett (LB) films of copolymer vinylidene fluoride with trifluorethylene. The surface 2D ferroelectric-paraelectric phase transition in the topmost layer of LB films and a thickness independent (almost 2D) transition in the bulk of these films are observed in temperature studies of SHG.Comment: 9 pages, 2 figures, Optics Letters, in prin

Insulin-Like Growth Factor-I Gene Polymorphism Associations with Growth, Body Composition, Skeleton Integrity, and Metabolic Traits

Molecular genetic selection on individual genes is a promising method to genetically improve economically important traits in chickens. A resource population was developed to study the genetics of growth, body composition, skeletal integrity, and metabolism traits. Broiler sires were crossed to dams of 2 diverse, highly inbred lines (Leghorn and Fayoumi), and the F1 birds were intermated by dam line to produce broiler-Leghorn and broiler-Fayoumi F2 offspring. Growth, body composition, skeletal integrity, and hormonal and metabolic factors were measured in 713 F2 individuals. Insulin-like growth factor-I (IGF1) was selected for study as a biological and positional candidate gene. A single nucleotide polymorphism (SNP) was identified between the founder lines in the IGF1 promoter region, and a PCR-RFLP assay was developed. A mixed model was used to statistically analyze associations of IGF1-SNP1 with phenotypic traits. The IGF1-SNP1 had significant associations with most recorded traits, except metabolic traits. Strong interactions between the IGF1 gene and genetic background on growth traits in the 2 F2 populations suggest that genetic interaction is an important aspect for consideration before using the IGF1-SNP1 in marker-assisted selection programs. Several beneficial effects (improved growth, increased breast muscle weight, decreased abdominal fat, and enhanced skeletal integrity) associated with 1 allele indicate the presence of 1 or more loci near IGF1-SNP1 controlling biologically diverse and economically important traits in chickens

Chicken Quantitative Trait Loci for Growth and Body Composition Associated with Transforming Growth Factor-β Genes1

Transforming growth factor-β (TGF-β) belongs to a large family of multifunctional growth factors that regulate a broad spectrum of biological activities involved in morphogenesis, development, and differentiation. The current study was designed to investigate the effects of TGF-β genes on chicken growth and body composition traits. The Iowa Growth and Composition Resource Population was established by crossing broiler sires with dams from two unrelated highly inbred lines (Leghorn and Fayoumi). The F1 birds were intercrossed, within dam line, to produce two related F2 populations. Body weight and body composition traits were measured in the F 2 population. Primers for TGF-β2, TGF-β3, and TGF-β4 were designed from database chicken sequence. Polymorphisms between parental lines were detected by DNA sequencing, and PCR-RFLP methods were then developed to screen the F2 population. The TGF-β2 polymorphisms between broiler and Leghorn and the TGF-β4 polymorphism between broiler and Fayoumi were associated with traits of skeletal integrity, such as tibia length, bone mineral content, bone mineral density, and the percentage of each measure to BW. The TGF-β3 polymorphism between broilers and Leghorns was associated with traits of growth and body composition, such as BW, average daily gain, weight of breast muscle, abdominal fat pad and spleen, as well as the percentage of these organ weights to BW, and the percentage of shank weight and length to BW. The current research supports the broad effects of TGF-β genes on growth and development of chickens

Medical students’ experiences of health inequalities and inclusion health education

Background Inclusion health groups experience a significantly larger burden of morbidity and mortality than the general public. Despite this, undergraduate medical education is often limited in its approach to inclusion health curricula, leaving students disengaged and lacking understanding. Methods We conducted two research studies to explore medical students’ experiences of inclusion health education. All participants were studying medicine at the University of Leeds at the time of data collection. We gathered experiences of both compulsory and elective inclusion health education via semi-structured interviews. Interview responses were audio-recorded, transcribed and analysed thematically. Findings We identified several key findings across the two studies. Firstly, medical students felt unprepared to work with inclusion health groups. Further to this, medical students have a preference for interactive teaching and learning in inclusion health education. Finally, encountering inclusion health groups by chance (on placement) or choice (optional initiatives) present different opportunities. Discussion and Conclusion Our research suggests that simply being exposed to inclusion health groups through lectures and on placement is not considered sufficient by medical students, and in fact can lead to the perpetuation of misinformation and stigma. Participants perceived that optional initiatives or ‘choice encounters’ had profoundly positive impacts on attitudes and interest, particularly when there were opportunities to learn directly from individuals with lived experience of exclusion. We suggest that a flipped classroom approach to inclusion health education along with integrated experiential learning would provide medical students with comprehensive and patient-focused learning opportunities

Properties of Ridges in Elastic Membranes

When a thin elastic sheet is confined to a region much smaller than its size the morphology of the resulting crumpled membrane is a network of straight ridges or folds that meet at sharp vertices. A virial theorem predicts the ratio of the total bending and stretching energies of a ridge. Small strains and curvatures persist far away from the ridge. We discuss several kinds of perturbations that distinguish a ridge in a crumpled sheet from an isolated ridge studied earlier (A. E. Lobkovsky, Phys. Rev. E. 53 3750 (1996)). Linear response as well as buckling properties are investigated. We find that quite generally, the energy of a ridge can change by no more than a finite fraction before it buckles.Comment: 13 pages, RevTeX, acknowledgement adde

4-Amino­pyridinium picrate

In the title compound, C5H7N2 +·C6H2N3O7 −, the 4-amino­pyridinium cation is essentially planar (r.m.s. deviation = 0.002 Å). The three nitro groups in the picrate anion are twisted away from the attached benzene ring [dihedral angles = 24.1 (1), 9.3 (3) and 21.4 (1)°]. In the crystal structure, the ions are linked into a three-dimensional network by N—H⋯O and C—H⋯O hydrogen bonds