ALTIRISCH ERULB N. Pr. M.

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The mapping class group and the Meyer function for plane curves

For each d>=2, the mapping class group for plane curves of degree d will be defined and it is proved that there exists uniquely the Meyer function on this group. In the case of d=4, using our Meyer function, we can define the local signature for 4-dimensional fiber spaces whose general fibers are non-hyperelliptic compact Riemann surfaces of genus 3. Some computations of our local signature will be given.Comment: 24 pages, typo adde

Resolved Measurements of X_(CO) in NGC 6946

We present the largest sample to date of giant molecular clouds (GMCs) in a substantial spiral galaxy other than the Milky Way. We map the distribution of molecular gas with high resolution and image fidelity within the central 5 kpc of the spiral galaxy NGC 6946 in the ^(12)CO (J = 1-0) transition. By combining observations from the Nobeyama Radio Observatory 45 m single dish telescope and the Combined Array for Research in Millimeter Astronomy interferometer, we are able to obtain high image fidelity and accurate measurements of L_CO compared with previous purely interferometric studies. We resolve individual GMCs, measure their luminosities and virial masses, and derive X CO—the conversion factor from CO measurements to H2 masses—within individual clouds. On average, we find that X_CO = 1.2 × 10^(20) cm^(–2) (K km s^(–1))^(–1), which is consistent within our uncertainties with previously derived Galactic values as well as the value we derive for Galactic GMCs above our mass sensitivity limit. The properties of our GMCs are largely consistent with the trends observed for molecular clouds detected in the Milky Way disk, with the exception of six clouds detected within ~400 pc of the center of NGC 6946, which exhibit larger velocity dispersions for a given size and luminosity, as has also been observed at the Galactic center

ISPRM discussion paper: Proposing a conceptual description of health-related rehabilitation services.

There is a need for a comprehensive classification system of health-related rehabilitation services. For conceptual clarity our aim is to provide a health-related conceptual description of the term rehabilitation service . First, we introduce a common understanding of the term rehabilitation , based on the current definition in the World Health Organization\u27s World Report on Disability, and a conceptual description of rehabilitation agreed upon by international Physical and Rehabilitation Medicine organizations. From a health perspective, rehabilitation can be regarded as a general health strategy with the aim of enabling persons with health conditions experiencing or likely to experience disability to achieve and maintain optimal functioning. Secondly, we distinguish different meanings of the term service , that have originated in management literature. It is important to distinguish between micro, meso and macro level uses of the term service . On a meso level, which is central for the classification of rehabilitation services, 2 aspects of a service, i.e. an offer of an intangible product and an organizational setting in which the offer is upheld, are both essential. The results of this conceptual analysis are used to develop a conceptual description of health-related rehabilitation, which is set out at the end of this paper. This conceptual description may provide the basis of a classification of health-related rehabilitation services, and is open for comments and discussion

Star Formation on Subkiloparsec Scale Triggered by Non-linear Processes in Nearby Spiral Galaxies

We report a super-linear correlation for the star formation law based on new CO(J = 1-0) data from the CARMA and NOBEYAMA Nearby-galaxies (CANON) CO survey. The sample includes 10 nearby spiral galaxies, in which structures at sub-kpc scales are spatially resolved. Combined with the star formation rate surface density traced by Hα and 24 μm images, CO(J = 1-0) data provide a super-linear slope of N = 1.3. The slope becomes even steeper (N = 1.8) when the diffuse stellar and dust background emission is subtracted from the Hα and 24 μm images. In contrast to the recent results with CO(J = 2-1) that found a constant star formation efficiency (SFE) in many spiral galaxies, these results suggest that the SFE is not independent of environment, but increases with molecular gas surface density. We suggest that the excitation of CO(J = 2-1) is likely enhanced in the regions with higher star formation and does not linearly trace the molecular gas mass. In addition, the diffuse emission contaminates the SFE measurement most in regions where the star formation rate is law. These two effects can flatten the power-law correlation and produce the apparent linear slope. The super-linear slope from the CO(J = 1-0) analysis indicates that star formation is enhanced by non-linear processes in regions of high gas density, e.g., gravitational collapse and cloud-cloud collisions

Physical Conditions in Molecular Clouds in the Arm and Interarm Regions of M51

We report systematic variations in the emission line ratio of the CO J = 2-1 and J = 1-0 transitions (R_(2-1/1-0)) in the grand-design spiral galaxy M51. The R_(2-1/1-0) ratio shows clear evidence for the evolution of molecular gas from the upstream interarm regions into the spiral arms and back into the downstream interarm regions. In the interarm regions, R_(2-1/1-0) is typically 0.7 (often 0.8-1.0) in the spiral arms, particularly at the leading (downstream) edge of the molecular arms. These trends are similar to those seen in Galactic GMCs with OB star formation (presumably in the Galactic spiral arms). R_(2-1/1-0) is also high, ~0.8-1.0, in the central region of M51. Analysis of the molecular excitation using a Large Velocity Gradient radiative transfer calculation provides insight into the changes in the physical conditions of molecular gas between the arm and interarm regions: cold and low-density gas (≾ 10 K, ≾ 300 cm^(–3)) is required for the interarm GMCs, but this gas must become warmer and/or denser in the more active star-forming spiral arms. The ratio R_(2-1/1-0) is higher in areas of high 24 μm dust surface brightness (which is an approximate tracer of star formation rate surface density) and high CO(1-0) integrated intensity (i.e., a well-calibrated tracer of total molecular gas surface density). The systematic enhancement of the CO(2-1) line relative to CO(1-0) in luminous star-forming regions suggests that some caution is needed when using CO(2-1) as a tracer of bulk molecular gas mass, especially when galactic structures are resolved

Resolved Giant Molecular Clouds in Nearby Spiral Galaxies: Insights from the CANON CO (1-0) Survey

We resolve 182 individual giant molecular clouds (GMCs) larger than 2.5 × 10^5 M ☉ in the inner disks of 5 large nearby spiral galaxies (NGC 2403, NGC 3031, NGC 4736, NGC 4826, and NGC 6946) to create the largest such sample of extragalactic GMCs within galaxies analogous to the Milky Way. Using a conservatively chosen sample of GMCs most likely to adhere to the virial assumption, we measure cloud sizes, velocity dispersions, and ^(12)CO (J = 1-0) luminosities and calculate cloud virial masses. The average conversion factor from CO flux to H_2 mass (or X_(CO)) for each galaxy is 1-2 × 10^(20) cm^(–2) (K km s^(–1))^(–1), all within a factor of two of the Milky Way disk value (~2 × 10^(20) cm^(–2) (K km s^(–1))^(–1)). We find GMCs to be generally consistent within our errors between the galaxies and with Milky Way disk GMCs; the intrinsic scatter between clouds is of order a factor of two. Consistent with previous studies in the Local Group, we find a linear relationship between cloud virial mass and CO luminosity, supporting the assumption that the clouds in this GMC sample are gravitationally bound. We do not detect a significant population of GMCs with elevated velocity dispersions for their sizes, as has been detected in the Galactic center. Though the range of metallicities probed in this study is narrow, the average conversion factors of these galaxies will serve to anchor the high metallicity end of metallicity-X_(CO) trends measured using conversion factors in resolved clouds; this has been previously possible primarily with Milky Way measurements

Giant molecular clouds in the non-grand design spiral galaxy NGC 6946

We present high spatial resolution observations of Giant Molecular Clouds (GMCs) in the eastern part of the nearby spiral galaxy NGC 6946 obtained with the Combined Array for Research in Millimeter-wave Astronomy (CARMA). We have observed 12CO(1-0), 12CO(2-1) and 13CO(1-0), achieving spatial resolutions of 5.4" x 5.0", 2.5" x 2.0" and 5.6" x 5.4" respectively over a region of 6 x 6 kpc. This region extends from 1.5 kpc to 8 kpc galactocentric radius, thus avoiding the intense star formation in the central kpc. We have recovered short-spacing u-v components by using single dish observations from the Nobeyama 45m and IRAM 30m telescopes. Using the automated CPROPS algorithm we identified 44 CO cloud complexes in the 12CO(1-0) map and 64 GMCs in the 12CO(2-1) maps. The sizes, line widths, and luminosities of the GMCs are similar to values found in other extragalactic studies. We have classified the clouds into on-arm and inter-arm clouds based on the stellar mass density traced by the 3.6 um map. On-arm clouds present in general higher star formation rates than clouds located on inter-arm regions. Although the star formation efficiency shows no systematic trend with galactocentric radius, some on-arm clouds -- which are more luminous and more massive compared to inter-arm GMCs -- are also forming stars more efficiently than the rest of the identified GMCs. These structures appear to be located on two specific regions in the spiral arms. One of them shows a strong gradient, suggesting that this region of high star formation efficiency may be the result of gas flow convergence.Comment: 23 pages, 21 figures, 3 tables. To be published in The Astrophysical Journa

The impact of interactions, bars, bulges, and AGN on star formation efficiency in local massive galaxies

Using observations from the GASS and COLD GASS surveys and complementary data from SDSS and GALEX, we investigate the nature of variations in gas depletion time observed across the local massive galaxy population. The large and unbiased COLD GASS sample allows us to assess the relative importance of galaxy interactions, bar instabilities, morphologies and the presence of AGN in regulating star formation efficiency. Both the H2 mass fraction and depletion time vary as a function of the distance of a galaxy from the main sequence in the SFR-M* plane. The longest gas depletion times are found in below-main sequence bulge-dominated galaxies that are either gas-poor, or else on average less efficient than disk-dominated galaxy at converting into stars any cold gas they may have. We find no link between AGN and these long depletion times. The galaxies undergoing mergers or showing signs of morphological disruptions have the shortest molecular gas depletion times, while those hosting strong stellar bars have only marginally higher global star formation efficiencies as compared to matched control samples. Our interpretation is that depletion time variations are caused by changes in the ratio between the gas mass traced by the CO(1-0) observations, and the gas mass in high density star-forming cores, with interactions, mergers and bar instabilities able to locally increase pressure and raise the ratio of efficiently star-forming gas to CO-detected gas. Building a sample representative of the local massive galaxy population, we derive a global Kennicutt-Schmidt relation of slope 1.18+/-0.24, and observe structure within the scatter around this relation, with galaxies having low (high) stellar mass surface densities lying systematically above (below) the mean relation, suggesting that gas surface density is not the only parameter driving the global star formation ability of a galaxy.Comment: 19 pages, 12 figures, accepted for publication in Ap

Fighting Enemies and Noise: Competition of Residents and Invaders in a Stochastically Fluctuating Environment

The possible control of competitive invasion by infection of the invader and multiplicative noise is studied. The basic model is the Lotka-Volterra competition system with emergent carrying capacities. Several stationary solutions of the non-infected and infected system are identified as well as parameter ranges of bistability. The latter are used for the numerical study of invasion phenomena. The diffusivities, the infection but in particular the white and coloured multiplicative noise are the control parameters. It is shown that not only competition, possible infection and mobilities are important drivers of the invasive dynamics but also the noise and especially its color and the functional response of populations to the emergence of noise