6,490 research outputs found
Thickening of galactic disks through clustered star formation
(Abridged) The building blocks of galaxies are star clusters. These form with
low-star formation efficiencies and, consequently, loose a large part of their
stars that expand outwards once the residual gas is expelled by the action of
the massive stars. Massive star clusters may thus add kinematically hot
components to galactic field populations. This kinematical imprint on the
stellar distribution function is estimated here by calculating the velocity
distribution function for ensembles of star-clusters distributed as power-law
or log-normal initial cluster mass functions (ICMFs). The resulting stellar
velocity distribution function is non-Gaussian and may be interpreted as being
composed of multiple kinematical sub-populations. The notion that the formation
of star-clusters may add hot kinematical components to a galaxy is applied to
the age--velocity-dispersion relation of the Milky Way disk to study the
implied history of clustered star formation, with an emphasis on the possible
origin of the thick disk.Comment: MNRAS, accepted, 27 pages, 9 figure
Dissolving star cluster candidates
We present a list of 34 neglected entries from star cluster catalogues
located at relatively high galactic latitudes ( 15) which
appear to be candidate late stages of star cluster dynamical evolution.
Although underpopulated with respect to usual open clusters, they still present
a high number density contrast as compared to the galactic field. This was
verified by means of (i) predicted model counts from different galactic
subsystems in the same direction, and (ii) Guide Star Catalog equal solid angle
counts for the object and surrounding fields. This suggests that the objects
are physical systems, possibly star clusters in the process of disruption or
their fossil remains. The sample will be useful for followup studies in view of
verifying their physi cal nature.Comment: manuscript in LATEX with 7 pages, 7 figures .ps Accepted for
Astronomy and Astrophysics main journa
Illicit cigarettes and hand-rolled tobacco in 18 European countries: a cross-sectional survey
Objective Little evidence, other than that commissioned by the tobacco industry, exists on the size of the illicit tobacco trade. This study addresses this gap by examining the level and nature of illicit cigarettes and hand-rolled tobacco in 18 European countries. Design Face-to-face cross-sectional survey on smoking. Setting 18 European countries. Participants For each country, around 1000 subjects representative of the population aged 15 and over were enrolled. Current cigarette smokers were asked to show their latest purchased pack of cigarettes or hand-rolled tobacco. Main outcome measure A comprehensive measure called an Identification of an Illicit Pack (IIP) was used to study the extent of illicit trade, defining a pack as illicit if it had at least one of the following tax evasion indicators: (1) it was bought from illicit sources, as reported by smokers, (2) it had an inappropriate tax stamp, (3) it had an inappropriate health warning or (4) its price was substantially below the known price in their market. Results Overall, the proportion of illicit packs was 6.5%. The highest prevalence of IIP was observed in Latvia (37.8%). Illicit packs were more frequent among less educated smokers and among those living in a country which shared a land or sea border with Ukraine, Russia, Moldova or Belarus. No significant association was found with price of cigarettes. Conclusions This study indicates that IIP is less than 7% in Europe and suggests that the supply of illicit tobacco, rather than its price, is a key factor contributing to tax evasion
Roll-your-own cigarettes in Europe:Use, weight and implications for fiscal policies
Excise duties on roll-your-own (RYO) tobacco, which are generally based on RYO cigarettes containing 1 g of tobacco, are lower than duties on factory-made (FM) cigarettes. This provides a price incentive for smokers to switch to RYO, the use of which is increasing across Europe. To effectively approximate duties on the two types of products, accurate data on the weight of RYO cigarettes are required. We provide updated information on RYO use and RYO cigarette weight across Europe. From a representative face-to-face survey conducted in 2010 in 18 European countries (Albania, Austria, Bulgaria, Czech Republic, Croatia, England, Finland, France, Greece, Hungary, Ireland, Italy, Latvia, Poland, Portugal, Romania, Spain and Sweden), we considered data from 5158 current smokers aged 15 years or above, with available information on daily consumption of FM and RYO cigarettes separately. In Europe, 10.4% of current smokers (12.9% of men and 7.5% of women) were 'predominant' RYO users (i.e. >50% of cigarettes smoked). This proportion was highest in England (27.3%), France (16.5%) and Finland (13.6%). The median weight of one RYO cigarette is 0.75 g (based on 192 smokers consuming exclusively RYO cigarettes). The proportion of RYO smokers is substantial in several European countries. Our finding on the weight of RYO cigarettes is consistent with the scientific literature and industry documents showing that the weight of RYO cigarettes is substantially lower than that of FM ones. Basing excise duties on RYO on an average cigarette weight of 0.75 g rather than 1 g would help increase the excise levels to those on FM cigarettes
From Galaxy Clusters to Ultra-Faint Dwarf Spheroidals: A Fundamental Curve Connecting Dispersion-supported Galaxies to Their Dark Matter Halos
We examine scaling relations of dispersion-supported galaxies over more than
eight orders of magnitude in luminosity by transforming standard fundamental
plane parameters into a space of mass (M1/2), radius (r1/2), and luminosity
(L1/2). We find that from ultra-faint dwarf spheroidals to giant cluster
spheroids, dispersion-supported galaxies scatter about a one-dimensional
"fundamental curve" through this MRL space. The weakness of the M1/2-L1/2 slope
on the faint end may imply that potential well depth limits galaxy formation in
small galaxies, while the stronger dependence on L1/2 on the bright end
suggests that baryonic physics limits galaxy formation in massive galaxies. The
mass-radius projection of this curve can be compared to median dark matter halo
mass profiles of LCDM halos in order to construct a virial mass-luminosity
relationship (Mvir-L) for galaxies that spans seven orders of magnitude in
Mvir. Independent of any global abundance or clustering information, we find
that (spheroidal) galaxy formation needs to be most efficient in halos of Mvir
~ 10^12 Msun and to become inefficient above and below this scale. Moreover,
this profile matching technique is most accurate at the high and low luminosity
extremes (where dark matter fractions are highest) and is therefore quite
complementary to statistical approaches that rely on having a well-sampled
luminosity function. We also consider the significance and utility of the
scatter about this relation, and find that in the dSph regime observational
errors are almost at the point where we can explore the intrinsic scatter in
the luminosity-virial mass relation. Finally, we note that purely stellar
systems like Globular Clusters and Ultra Compact Dwarfs do not follow the
fundamental curve relation. This allows them to be easily distinguished from
dark-matter dominated dSph galaxies in MRL space. (abridged)Comment: 27 pages, 18 figures, ApJ accepted. High-res movies of 3D figures are
available at http://www.physics.uci.edu/~bullock/fcurve/movies.htm
Support for a tobacco endgame strategy in 18 European countries
OBJECTIVE
The feasibility of a tobacco endgame strategy, aiming to bring smoking prevalence to near-zero levels, is currently under debate. We provide information on public support for such a strategy in Europe.
METHODS
In 2010 we conducted a face-to-face representative survey in 18 European countries (Albania, Austria, Bulgaria, the Czech Republic, Croatia, England, Finland, France, Greece, Hungary, Ireland, Italy, Latvia, Poland, Portugal, Romania, Spain and Sweden). The present analysis is based on 16,947 individuals aged ≥15years providing information on their attitudes towards a complete ban on the use or sale of tobacco.
RESULTS
Overall, 34.9% of adults (32.8% in men and 37.0% in women; p<0.001) supported a complete ban strategy on use or sale of tobacco, 41.2% of never, 29.4% of ex- and 25.6% of current smokers. The highest support was observed in southern Europe (42.5%), followed by eastern (39.1%), northern (27.5%) and western Europe (23.0%; p<0.001). A significant inverse trend was observed with both age and education.
CONCLUSION
Approximately one in three adults (and one in four smokers) supports a comprehensive tobacco endgame intervention. This first study in Europe provides a baseline for evaluating future trends in public support for extreme propositions to end or drastically cut smoking
The Geometry of Quantum Mechanics
A recent notion in theoretical physics is that not all quantum theories arise
from quantising a classical system. Also, a given quantum model may possess
more than just one classical limit. These facts find strong evidence in string
duality and M-theory, and it has been suggested that they should also have a
counterpart in quantum mechanics. In view of these developments we propose
"dequantisation", a mechanism to render a quantum theory classical.
Specifically, we present a geometric procedure to "dequantise" a given quantum
mechanics (regardless of its classical origin, if any) to possibly different
classical limits, whose quantisation gives back the original quantum theory.
The standard classical limit arises as a particular case of our
approach.Comment: 15 pages, LaTe
A novel source of arterial valve cell linked to bicuspid aortic valve without rephe in mice
Abnormalities of the arterial valve leaflets, predominantly bicuspid aortic valve, are the commonest congenital malformations. Although many studies have investigated the development of the arterial valves, it has been assumed that, as with the atrioventricular valves, endocardial to mesenchymal transition (EndMT) is the predominant mechanism. We show that arterial is distinctly different from atrioventricular valve formation. Whilst the four septal valve leaflets are dominated by NCC and EndMT-derived cells, the intercalated leaflets differentiate directly from Tnnt2-Cre+/Isl1+ progenitors in the outflow wall, via a Notch-Jag dependent mechanism. Further, when this novel group of progenitors are disrupted, development of the intercalated leaflets is disrupted, resulting in leaflet dysplasia and bicuspid valves without raphe, most commonly affecting the aortic valve. This study thus overturns the dogma that heart valves are formed principally by EndMT, identifies a new source of valve interstitial cells, and provides a novel mechanism for causation of bicuspid aortic valves without raphe.British Heart Foundation RG/12/15/29935 Lorriane Eley Rachel V Richardson Lindsay Murphy Bill Chaudhry Deborah J Henderson; British Heart Foundation PG/15/46/31589 Lorriane Eley Bill Chaudhry Deborah J Henderson; Ministerio de Ciencia, Innovacion y Universidades of Spain CB16/11/00399 (Ciber Cardiovascular) Donal MacGrogan Alejandro Salguero-Jimenez Jose Luis de La Pompa; Ministerio de Ciencia, Innovacion y Universidades of Spain SAF2016-78370-R Donal MacGrogan Alejandro Salguero-Jimenez Jose Luis de La Pompa; Ministerio de Ciencia, Innovacion y Universidades of Spain RD16/0011/0021 (Red de Terapia Celular, TERCEL) Donal MacGrogan Alejandro Salguero-Jimenez Jose Luis de La Pompa; The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.S
Smokeless tobacco use in Sweden and other 17 European countries
Introduction: The purpose of this study is to report prevalence and determinants of use of smokeless tobacco in a representative sample of men and women from Sweden, where Swedish snus sales are legal, and from 17 other European countries, where sales of smokeless tobacco are restricted. Methods: In 2010, a face-to-face survey including information on current smokeless tobacco use was conducted in a representative sample of around 1000 individuals aged 6515 years per country in Albania, Austria, Bulgaria, Czech Republic, Croatia, England, Finland, France, Greece, Hungary, Ireland, Italy, Latvia, Poland, Portugal, Romania, Spain and Sweden. Results: In Sweden, the overall prevalence of smokeless tobacco use was 12.3% (20.7% in men, 3.5% in women). The corresponding estimate for other European countries combined was 1.1% (1.2% in men, 1.1% in women). Compared with never smokers, former smokers in Sweden were significantly more likely to use smokeless tobacco (odds ratio, OR: 2.67), whereas no difference in use was observed in other countries (OR: 1.04). Use of smokeless tobacco was similar among current smokers in Sweden (OR: 1.96) and in other countries (OR: 2.40) when contrasted to never smokers. In Sweden there were no differences in the number of cigarettes/day between smokers who also use smokeless tobacco (13.3 cigarettes/day) and exclusive cigarette smokers (12.9 cigarettes/day; P = 0.785). Conclusions: Excluding Sweden, current oral tobacco use was not commonly reported in the European countries surveyed and was similarly rare both in men and in women. In Sweden, however, use of smokeless tobacco was about 10-fold higher than the rest of Europe and more prevalent in men than in women
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