Experimental evidence of a natural parity state in 26^{26}Mg and its impact to the production of neutrons for the s process

We have studied natural parity states in $^{26}$Mg via the $^{22}$Ne($^{6}$Li,d)$^{26}$Mg reaction. Our method significantly improves the energy resolution of previous experiments and, as a result, we report the observation of a natural parity state in $^{26}$Mg. Possible spin-parity assignments are suggested on the basis of published $\gamma$-ray decay experiments. The stellar rate of the $^{22}$Ne($\alpha$,$\gamma$)$^{26}$Mg reaction is reduced and may give rise to an increase in the production of s-process neutrons via the $^{22}$Ne($\alpha$,n)$^{25}$Mg reaction.Comment: Published in PR

Affine T-varieties of complexity one and locally nilpotent derivations

Let X=spec A be a normal affine variety over an algebraically closed field k of characteristic 0 endowed with an effective action of a torus T of dimension n. Let also D be a homogeneous locally nilpotent derivation on the normal affine Z^n-graded domain A, so that D generates a k_+-action on X that is normalized by the T-action. We provide a complete classification of pairs (X,D) in two cases: for toric varieties (n=\dim X) and in the case where n=\dim X-1. This generalizes previously known results for surfaces due to Flenner and Zaidenberg. As an application we compute the homogeneous Makar-Limanov invariant of such varieties. In particular we exhibit a family of non-rational varieties with trivial Makar-Limanov invariant.Comment: 31 pages. Minor changes in the structure. Fixed some typo

Measurement of O17(p,γ)F18 between the narrow resonances at Erlab=193 and 519keV

The O17(p,γ)F18 reaction sensitively influences hydrogen burning nucleosynthesis in a number of stellar sites, including classical novae. These thermonuclear explosions, taking place in close binary star systems, produce peak temperatures in the range of T=100-400 MK. Recent results indicate that the thermonuclear rates for this reaction in this particular temperature range are dominated by the direct capture process. We report on the measurement of the O17(p,γ)F18 cross section between the narrow resonances at Erlab=193 and 519keV, where the S factor is expected to vary smoothly with energy. We extract the direct capture contribution from the total cross section and demonstrate that earlier data are inconsistent with our results

Resonance strength in Ne22(p,γ)Na23 from depth profiling in aluminum

A novel method for extracting absolute resonance strengths has been investigated. By implanting Ne22 ions into a thick aluminum backing and simultaneously measuring the Ne22+p and Al27+p reactions, the strength of the Erlab=479 keV resonance in Ne22(p,γ)Na23 was determined to be ωγ=0.524(51) eV. This result has significantly reduced uncertainties compared to earlier work. Our results are important for the absolute normalizations of resonance strengths in the Ne22(p,γ)Na23 hydrogen-burning reaction and in the Ne22+α s-process neutron-source reactions

Atomic and Molecular Gas Components in Spiral Galaxies of the Virgo Cluster

Based on two models, we investigate the molecular-to-atomic gas ratio in Virgo cluster galaxies in comparison with field galaxies. We show that the enhanced metallicity for cluster members and the ram pressure stripping of atomic gas from the disk periphery cannot fully explain the observed gas component ratios. The additional environmental factors affecting the interstellar medium and leading to an increase in the molecular gas fraction should be taken into account for cluster galaxies.Comment: 11 pages, 4 figure

A systematic review of the effectiveness and cost-effectiveness of peer education and peer support in prisons.

BACKGROUND: Prisoners experience significantly worse health than the general population. This review examines the effectiveness and cost-effectiveness of peer interventions in prison settings. METHODS: A mixed methods systematic review of effectiveness and cost-effectiveness studies, including qualitative and quantitative synthesis was conducted. In addition to grey literature identified and searches of websites, nineteen electronic databases were searched from 1985 to 2012. Study selection criteria were: Population: Prisoners resident in adult prisons and children resident in Young Offender Institutions (YOIs). INTERVENTION: Peer-based interventions Comparators: Review questions 3 and 4 compared peer and professionally led approaches. OUTCOMES: Prisoner health or determinants of health; organisational/ process outcomes; views of prison populations. STUDY DESIGNS: Quantitative, qualitative and mixed method evaluations. RESULTS: Fifty-seven studies were included in the effectiveness review and one study in the cost-effectiveness review; most were of poor methodological quality. Evidence suggested that peer education interventions are effective at reducing risky behaviours, and that peer support services are acceptable within the prison environment and have a positive effect on recipients, practically or emotionally. Consistent evidence from many, predominantly qualitative, studies, suggested that being a peer deliverer was associated with positive effects. There was little evidence on cost-effectiveness of peer-based interventions. CONCLUSIONS: There is consistent evidence from a large number of studies that being a peer worker is associated with positive health; peer support services are also an acceptable source of help within the prison environment and can have a positive effect on recipients. Research into cost-effectiveness is sparse. SYSTEMATIC REVIEW REGISTRATION: PROSPERO ref: CRD42012002349

The rapid formation a large rotating disk galaxy three billion years after the Big Bang

[Abridged] Over the past two decades observations and theoretical simulations have established a global frame-work of galaxy formation and evolution in the young Universe. Galaxies formed as baryonic gas cooled at the centres of collapsing dark matter halos. Mergers of halos led to the build up of galaxy mass. A major step forward in understanding these issues requires well resolved physical information on individual galaxies at high redshift. Here we report adaptive optics, spectroscopic observations of a representative luminous star forming galaxy when the Universe was only twenty percent of its age. The superior angular resolution of these data reveals the physical and dynamical properties of a high redshift galaxy in unprecedented detail. A large and massive rotating proto-disk is channelling gas towards a growing central stellar bulge hosting an accreting massive black hole.Comment: Narure, accepted (Released Aug 17th

Spiral structure in nearby galaxies I. Sample, data analysis, and overview of results

This paper, the first of two, introduces an observational study of spiral structure in galaxies chosen from the SINGS survey. Near infrared (NIR) and optical data are used to produce mass surface density maps, and from these the morphology of the disc is examined. The aim of this work is to characterise the prevalence of spiral structure in this sample and, in the cases where a clear spiral pattern is found, include the findings in a comparative study (reported in paper II). A two-armed (`grand design') spiral pattern is found in approximately half the galaxies studied, including all those that are designated as grand design in the optical, but also including some, but not all, optically flocculent galaxies. It is found that the level of non-axisymmetric structure in the galaxies' mass distributions is only modestly higher in those galaxies that are classified as `grand design' compared with those that are not, implying that non-grand design galaxies possess significant power in higher order modes. There is no evidence that bars preferentially trigger the spirals, but they do appear to stir up non-axisymmetric structure in the disc. In contrast, there is evidence that strong/close tidal interactions with companion galaxies are associated with strong two-armed spiral structure in the infrared, though there are a number of galaxies with relatively weak infrared spiral structure that do not possess such companions.Comment: 28 pages, 56 figures. Accepted for publication in MNRA