Stellar Motion around Spiral Arms: Gaia Mock Data

We compare the stellar motion around a spiral arm created in two different scenarios, transient/co-rotating spiral arms and density-wave-like spiral arms. We generate Gaia mock data from snapshots of the simulations following these two scenarios using our stellar population code, SNAPDRAGONS, which takes into account dust extinction and the expected Gaia errors. We compare the observed rotation velocity around a spiral arm similar in position to the Perseus arm, and find that there is a clear difference in the velocity features around the spiral arm between the co-rotating spiral arm and the density-wave-like spiral arm. Our result demonstrates that the volume and accuracy of the Gaia data are sufficient to clearly distinguish these two scenarios of the spiral arms.Comment: 5 pages, 1 figure, to appear in the proceedings of "The Milky Way Unravelled by Gaia: GREAT Science from the Gaia Data Releases", Barcelona, 1-5 December 2014, eds. N. Walton, F. Figueras, C. Soubira

Chromosome conformation maps in fission yeast reveal cell cycle dependent sub nuclear structure

Successful progression through the cell cycle requires spatial and temporal regulation of gene transcript levels and the number, positions and condensation levels of chromosomes. Here we present a high resolution survey of genome interactions in Schizosaccharomyces pombe using synchronized cells to investigate cell cycle dependent changes in genome organization and transcription. Cell cycle dependent interactions were captured between and within S. pombe chromosomes. Known features of genome organization (e.g. the clustering of telomeres and retrotransposon long terminal repeats (LTRs)) were observed throughout the cell cycle. There were clear correlations between transcript levels and chromosomal interactions between genes, consistent with a role for interactions in transcriptional regulation at specific stages of the cell cycle. In silico reconstructions of the chromosome organization within the S. pombe nuclei were made by polymer modeling. These models suggest that groups of genes with high and low, or differentially regulated transcript levels have preferred positions within the S. pombe nucleus. We conclude that the S. pombe nucleus is spatially divided into functional sub-nuclear domains that correlate with gene activity. The observation that chromosomal interactions are maintained even when chromosomes are fully condensed in M phase implicates genome organization in epigenetic inheritance and bookmarking

Healthcare choice: Discourses, perceptions, experiences and practices

Policy discourse shaped by neoliberal ideology, with its emphasis on marketisation and competition, has highlighted the importance of choice in the context of healthcare and health systems globally. Yet, evidence about how so-called consumers perceive and experience healthcare choice is in short supply and limited to specific healthcare systems, primarily in the Global North. This special issue aims to explore how choice is perceived and utilised in the context of different systems of healthcare throughout the world, where choice, at least in policy and organisational terms, has been embedded for some time. The articles are divided into those emphasising: embodiment and the meaning of choice; social processes associated with choice; the uncertainties, risks and trust involved in making choices; and issues of access and inequality associated with enacting choice. These sociological studies reveal complexities not always captured in policy discourse and suggest that the commodification of healthcare is particularly problematic

Economics of education research: a review and future prospects

In this paper we offer an appraisal of the economics of education research area, charting its history as a field and discussing the ways in which economists have contributed both to education research and to education policy-making. In particular, we highlight the theoretical and methodological contributions that economists have made to the field of education during the last 50 years. Despite the success of the economics of education as a field of inquiry, we argue that some of the contributions made by economists could be limited if the economics of education is seen as quite distinct from the other disciplines working in the field of education. In these areas of common interest, economists need to work side by side with the other major disciplines in the field of education if their contribution to the field is to be maximised, particularly in terms of applying improved methodology. We conclude that the study of education acquisition and its economic and social impact in the economics of education research area is very likely to remain a fertile research ground. Acknowledgement

Interaction of reed and acoustic resonator in clarinetlike systems

Sound emergence in clarinetlike instruments is investigated in terms of instability of the static regime. Various models of reed-bore coupling are considered, from the pioneering work of Wilson and Beavers ["Operating modes of the clarinet", J. Acoust. Soc. Am. 56, 653--658 (1974)] to more recent modeling including viscothermal bore losses and vena contracta at the reed inlet. The pressure threshold above which these models may oscillate as well as the frequency of oscillation at threshold are calculated. In addition to Wilson and Beavers' previous conclusions concerning the role of the reed damping in the selection of the register the instrument will play on, the influence of the reed motion induced flow is also emphasized, particularly its effect on playing frequencies, contributing to reduce discrepancies between Wilson and Beavers' experimental results and theory, despite discrepancies still remain concerning the pressure threshold. Finally, analytical approximations of the oscillating solution based on Fourier series expansion are obtained in the vicinity of the threshold of oscillation. This allows to emphasize the conditions which determine the nature of the bifurcation (direct or inverse) through which the note may emerge, with therefore important consequences on the musical playing performances

Spin Dependent Fragmentation Functions for Heavy Flavor Baryons and Single Heavy Hyperon Polarization

Spin dependent fragmentation functions for heavy flavor quarks to fragment into heavy baryons are calculated in a quark-diquark model. The production of intermediate spin 1/2 and 3/2 excited states is explicity included. $\Lambda_b$ , $\Lambda_c$ and $\Xi_c$ production rate and polarization at LEP energies are calculated and, where possible, compared with experiment. A different approach, also relying on a heavy quark-diquark model, is proposed for the small momentum transfer inclusive production of polarized heavy flavor hyperons. The predicted $\Lambda_c$ polarization is roughly in agreement with experiment.Comment: LaTeX2e 11 pages with 4 PostScript figures. To be published in Proceedings of the International Workshop ``Symmetries and spin'', Praha-SPIN-200

Hyperon Polarization in the Constituent Quark Model

We consider mechanism for hyperon polarization in inclusive production. The main role belongs to the orbital angular momentum and polarization of the strange quark-antiquark pairs in the internal structure of the constituent quarks. We consider a nucleon as a core consisting of the constituent quarks embedded into quark condensate. The nonperturbative hadron structure is based on the results of chiral quark models.Comment: 14 pages, LaTeX, 2 Figures, References adde

Evidence of ongoing radial migration in NGC 6754: Azimuthal variations of the gas properties

Understanding the nature of spiral structure in disk galaxies is one of the main, and still unsolved questions in galactic astronomy. However, theoretical works are proposing new testable predictions whose detection is becoming feasible with recent development in instrumentation. In particular, streaming motions along spiral arms are expected to induce azimuthal variations in the chemical composition of a galaxy at a given galactic radius. In this letter we analyse the gas content in NGC 6754 with VLT/MUSE data to characterise its 2D chemical composition and H$\alpha$ line-of-sight velocity distribution. We find that the trailing (leading) edge of the NGC 6754 spiral arms show signatures of tangentially-slower, radially-outward (tangentially-faster, radially-inward) streaming motions of metal-rich (poor) gas over a large range of radii. These results show direct evidence of gas radial migration for the first time. We compare our results with the gas behaviour in a $N$-body disk simulation showing spiral morphological features rotating with a similar speed as the gas at every radius, in good agreement with the observed trend. This indicates that the spiral arm features in NGC 6754 may be transient and rotate similarly as the gas does at a large range of radii.Comment: 8 pages, 4 figures, accepted for publication in ApJL 2016 September 2

Ridge subduction sparked reorganization of the Pacific plate-mantle system 60-50 million years ago

A reorganization centered on the Pacific plate occurred ~53–47 million years ago. A “top-down” plate tectonic mechanism, complete subduction of the Izanagi plate, as opposed to a “bottom-up” mantle flow mechanism, has been proposed as the main driver. Verification based on marine geophysical observations is impossible as most ocean crust recording this event has been subducted. Using a forward modeling approach, which assimilates surface plate velocities and shallow thermal structure of slabs into mantle flow models, we show that complete Izanagi plate subduction and margin-wide slab detachment induced a major change in sub-Pacific mantle flow, from dominantly southward before 60 Ma to north-northeastward after 50 Ma. Our results agree with onshore geology, mantle tomography, and the inferred motion of the Hawaiian hot spot and are consistent with a plate tectonic process driving the rapid plate-mantle reorganization in the Pacific hemisphere between 60 and 50 Ma. This reorganization is reflected in tectonic changes in the Pacific and surrounding ocean basins