Stellar populations of bulges at low redshift

This chapter summarizes our current understanding of the stellar population properties of bulges and outlines important future research directions.Comment: Review article to appear in "Galactic Bulges", Editors: Laurikainen E., Peletier R., Gadotti D., Springer Publishing. 34 pages, 12 figure

Physical inactivity in nine European and Central Asian countries: an analysis of national population-based survey results

Background Physical inactivity is a major risk factor for non-communicable diseases. However, recent and systematically obtained national-level data to guide policy responses are often lacking, especially in countries in Eastern Europe and Central Asia. This article describes physical inactivity patterns among adults in Armenia, Azerbaijan, Belarus, Georgia, Kyrgyzstan, Republic of Moldova, Tajikistan, Turkey and Uzbekistan. Methods Data were collected using the Global Physical Activity Questionnaire drawing nationally representative samples of adults in each country. The national prevalence of physical inactivity was calculated as well as the proportional contribution to total physical activity (PA) during work, transport and leisure-time. An adjusted logistic regression model was applied to analyze the association of age, gender, education, household status and income with physical inactivity. Results National prevalence of physical inactivity ranged from 10.1% to 43.6%. The highest proportion of PA was registered during work or in the household in most countries, whereas the lowest was during leisure-time in all countries. Physical inactivity was more likely with older age in eight countries, with female gender in three countries, and with living alone in three countries. There was no clear pattern of association with education and income. Conclusion Prevalence of physical inactivity is heterogeneous across the region. PA during leisure-time contributes minimally to total PA in all countries. Policies and programs that increase opportunities for active travel and leisure-time PA, especially for older adults, women and people living alone will be an essential part of strategies to increase overall population PA.The authors gratefully acknowledge support from a grant from the Government of the Russian Federation in the context of the WHO European Office for the Prevention and Control of NCDs

Gas Accretion and Galactic Chemical Evolution: Theory and Observations

This chapter reviews how galactic inflows influence galaxy metallicity. The goal is to discuss predictions from theoretical models, but particular emphasis is placed on the insights that result from using models to interpret observations. Even as the classical G-dwarf problem endures in the latest round of observational confirmation, a rich and tantalizing new phenomenology of relationships between $M_*$, $Z$, SFR, and gas fraction is emerging both in observations and in theoretical models. A consensus interpretation is emerging in which star-forming galaxies do most of their growing in a quiescent way that balances gas inflows and gas processing, and metal dilution with enrichment. Models that explicitly invoke this idea via equilibrium conditions can be used to infer inflow rates from observations, while models that do not assume equilibrium growth tend to recover it self-consistently. Mergers are an overall subdominant mechanism for delivering fresh gas to galaxies, but they trigger radial flows of previously-accreted gas that flatten radial gas-phase metallicity gradients and temporarily suppress central metallicities. Radial gradients are generically expected to be steep at early times and then flattened by mergers and enriched inflows of recycled gas at late times. However, further theoretical work is required in order to understand how to interpret observations. Likewise, more observational work is needed in order to understand how metallicity gradients evolve to high redshifts.Comment: Invited review to appear in Gas Accretion onto Galaxies, Astrophysics and Space Science Library, eds. A. J. Fox & R. Dav\'e, to be published by Springer. 29 pages, 2 figure

The Milky Way Bulge: Observed properties and a comparison to external galaxies

The Milky Way bulge offers a unique opportunity to investigate in detail the role that different processes such as dynamical instabilities, hierarchical merging, and dissipational collapse may have played in the history of the Galaxy formation and evolution based on its resolved stellar population properties. Large observation programmes and surveys of the bulge are providing for the first time a look into the global view of the Milky Way bulge that can be compared with the bulges of other galaxies, and be used as a template for detailed comparison with models. The Milky Way has been shown to have a box/peanut (B/P) bulge and recent evidence seems to suggest the presence of an additional spheroidal component. In this review we summarise the global chemical abundances, kinematics and structural properties that allow us to disentangle these multiple components and provide constraints to understand their origin. The investigation of both detailed and global properties of the bulge now provide us with the opportunity to characterise the bulge as observed in models, and to place the mixed component bulge scenario in the general context of external galaxies. When writing this review, we considered the perspectives of researchers working with the Milky Way and researchers working with external galaxies. It is an attempt to approach both communities for a fruitful exchange of ideas.Comment: Review article to appear in "Galactic Bulges", Editors: Laurikainen E., Peletier R., Gadotti D., Springer Publishing. 36 pages, 10 figure

Origin of the Metallicity Distribution in the Thick Disc

Aims. Using a suite of cosmological chemodynamical disc galaxy simulations, we assess how (a) radial metallicity gradients evolve with scaleheight; (b) the vertical metallicity gradients change through the thick disc; and (c) the vertical gradient of the stellar rotation velocity varies through the disc. We compare with the Milky Way to search for analogous trends. Methods. We analyse five simulated spiral galaxies with masses comparable to the Milky Way. The simulations span a range of star formation and energy feedback strengths and prescriptions, particle- and grid-based hydrodynamical implementations, as well as initial conditions/assembly history. Disc stars are identified initially via kinematic decomposition, with a posteriori spatial cuts providing the final sample from which radial and vertical gradients are inferred. Results. Consistently, we find that the steeper, negative, radial metallicity gradients seen in the mid-plane flatten with increasing height away from the plane. In simulations with stronger (and/or more spatially-extended) feedback, the negative radial gradients invert, becoming positive for heights in excess of !1 kpc. Such behaviour is consistent with that inferred from recent observations. Our measurements of the vertical metallicity gradients show no clear correlation with galactocentric radius, and are in good agreement with those observed in the Milky Way’s thick disc (locally). Each of the simulations presents a decline in rotational velocity with increasing height from the mid-plane, albeit the majority have shallower kinematic gradients than that of the Milky Way. Conclusions. Simulations employing stronger/more extended feedback prescriptions possess radial and vertical metallicity and kinematic gradients more in line with recent observations. The inverted, positive, radial metallicity gradients seen in the simulated thick stellar discs originate from a population of younger, more metal-rich, stars formed in-situ, superimposed upon a background population of older migrators from the inner disc; the contrast provided by the former increases radially, due to the inside-out growth of the disc. A similar behaviour may be responsible for the same flattening seen in the radial gradients with scaleheight in the Milky Way

The stellar orbit distribution in present-day galaxies inferred from the CALIFA survey

Galaxy formation entails the hierarchical assembly of mass, along with the condensation of baryons and the ensuing, self-regulating star formation. The stars form a collisionless system whose orbit distribution retains dynamical memory that can constrain a galaxy's formation history. The ordered-rotation dominated orbits with near maximum circularity $\lambda_z \simeq1$ and the random-motion dominated orbits with low circularity $\lambda_z \simeq0$ are called kinematically cold and kinematically hot, respectively. The fraction of stars on `cold' orbits, compared to the fraction of stars on `hot' orbits, speaks directly to the quiescence or violence of the galaxies' formation histories. Here we present such orbit distributions, derived from stellar kinematic maps via orbit-based modelling for a well defined, large sample of 300 nearby galaxies. The sample, drawn from the CALIFA survey, includes the main morphological galaxy types and spans the total stellar mass range from $10^{8.7}$ to $10^{11.9}$ solar masses. Our analysis derives the orbit-circularity distribution as a function of galaxy mass, $p(\lambda_z~|~M_\star)$, and its volume-averaged total distribution, $p(\lambda_z)$. We find that across most of the considered mass range and across morphological types, there are more stars on `warm' orbits defined as $0.25\le \lambda_z \le 0.8$ than on either `cold' or `hot' orbits. This orbit-based "Hubble diagram" provides a benchmark for galaxy formation simulations in a cosmological context

Genetic Evidence for Involvement of Neuronally Expressed S1P1 Receptor in Nociceptor Sensitization and Inflammatory Pain

Sphingosine-1-phosphate (S1P) is a key regulator of immune response. Immune cells, epithelia and blood cells generate high levels of S1P in inflamed tissue. However, it is not known if S1P acts on the endings of nociceptive neurons, thereby contributing to the generation of inflammatory pain. We found that the S1P1 receptor for S1P is expressed in subpopulations of sensory neurons including nociceptors. Both S1P and agonists at the S1P1 receptor induced hypersensitivity to noxious thermal stimulation in vitro and in vivo. S1P-induced hypersensitivity was strongly attenuated in mice lacking TRPV1 channels. S1P and inflammation-induced hypersensitivity was significantly reduced in mice with a conditional nociceptor-specific deletion of the S1P1 receptor. Our data show that neuronally expressed S1P1 receptors play a significant role in regulating nociceptor function and that S1P/S1P1 signaling may be a key player in the onset of thermal hypersensitivity and hyperalgesia associated with inflammation