850 research outputs found
Triangulating Abuse Liability Assessment for Flavoured Cigar Products Using Physiological, Behavioural Economic and Subjective Assessments: A Within-subjects Clinical Laboratory Protocol
Introduction In the USA, Food and Drug Administration regulations prohibit the sale of flavoured cigarettes, with menthol being the exception. However, the manufacture, advertisement and sale of flavoured cigar products are permitted. Such flavourings influence positive perceptions of tobacco products and are linked to increased use. Flavourings may mask the taste of tobacco and enhance smoke inhalation, influencing toxicant exposure and abuse liability among novice tobacco users. Using clinical laboratory methods, this study investigates how flavour availability affects measures of abuse liability in young adult cigarette smokers. The specific aims are to evaluate the effect of cigar flavours on nicotine exposure, and behavioural and subjective measures of abuse liability.
Methods and analyses Participants (projected n=25) are healthy smokers of five or more cigarettes per day over the past 3 months, 18–25 years old, naive to cigar use (lifetime use of 50 or fewer cigar products and no more than 10 cigars smoked in the past 30 days) and without a desire to quit cigarette smoking in the next 30 days. Participants complete five laboratory sessions in a Latin square design with either their own brand cigarette or a session-specific Black & Mild cigar differing in flavour (apple, cream, original and wine). Participants are single-blinded to cigar flavours. Each session consists of two 10-puff smoking bouts (30 s interpuff interval) separated by 1 hour. Primary outcomes include saliva nicotine concentration, behavioural economic task performance and response to various questionnaire items assessing subjective effects predictive of abuse liability. Differences in outcomes across own brand cigarette and flavoured cigar conditions will be tested using linear mixed models
Classical Cepheid Pulsation Models. III. The Predictable Scenario
Within the current uncertainties in the treatment of the coupling between
pulsation and convection, limiting amplitude, nonlinear, convective models
appear the only viable approach for providing theoretical predictions about the
intrinsic properties of radial pulsators. In this paper we present the results
of a comprehensive set of Cepheid models computed within such theoretical
framework for selected assumptions on their original chemical composition.Comment: 24 pages, 1 latex file containing 6 tables, 10 postscript figures,
accepted for publication on Ap
DEM of triaxial tests on crushable cemented sand
Using the discrete element method, triaxial simulations of cemented sand consisting of crushable particles are presented. The triaxial model used features a flexible membrane, allowing realistic deformation to occur, and cementation is modelled using inter-particle bonds. The effects of particle crushing are explored, as is the influence of cementation on the behaviour of the soil. An insight to the effects that cementation has on the degree of crushing is presented
Localized-magnon states in strongly frustrated quantum spin lattices
Recent developments concerning localized-magnon eigenstates in strongly
frustrated spin lattices and their effect on the low-temperature physics of
these systems in high magnetic fields are reviewed. After illustrating the
construction and the properties of localized-magnon states we describe the
plateau and the jump in the magnetization process caused by these states.
Considering appropriate lattice deformations fitting to the localized magnons
we discuss a spin-Peierls instability in high magnetic fields related to these
states. Last but not least we consider the degeneracy of the localized-magnon
eigenstates and the related thermodynamics in high magnetic fields. In
particular, we discuss the low-temperature maximum in the isothermal entropy
versus field curve and the resulting enhanced magnetocaloric effect, which
allows efficient magnetic cooling from quite large temperatures down to very
low ones.Comment: 21 pages, 10 figures, invited paper for a special issue of "Low
Temperature Physics " dedicated to the 70-th anniversary of creation of
concept "antiferromagnetism" in physics of magnetis
Spectroscopic Signatures of Extra-Tidal Stars Around the Globular Clusters NGC 6656 (M22), NGC 3201 and NGC 1851 from RAVE
Stellar population studies of globular clusters have suggested that the
brightest clusters in the Galaxy might actually be the remnant nuclei of dwarf
spheroidal galaxies. If the present Galactic globular clusters formed within
larger stellar systems, they are likely surrounded by extra-tidal halos and/or
tails made up of stars that were tidally stripped from their parent systems.
The stellar surroundings around globular clusters are therefore one of the best
places to look for the remnants of an ancient dwarf galaxy. Here an attempt is
made to search for tidal debris around the supernovae enriched globular
clusters M22 and NGC 1851 as well as the kinematically unique cluster NGC 3201.
The stellar parameters from the Radial Velocity Experiment (RAVE) are used to
identify stars with RAVE metallicities, radial velocities and
elemental-abundances consistent with the abundance patterns and properties of
the stars in M22, NGC 1851 and NGC 3201. The discovery of RAVE stars that may
be associated with M22 and NGC 1851 are reported, some of which are at
projected distances of ~10 degrees away from the core of these clusters.
Numerous RAVE stars associated with NGC 3201 suggest that either the tidal
radius of this cluster is underestimated, or that there are some unbound stars
extending a few arc minutes from the edge of the cluster's radius. No further
extra-tidal stars associated with NGC 3201 could be identified. The bright
magnitudes of the RAVE stars make them easy targets for high resolution
follow-up observations, allowing an eventual further chemical tagging to
solidify (or exclude) stars outside the tidal radius of the cluster as tidal
debris. In both our radial velocity histograms of the regions surrounding NGC
1851 and NGC 3201, a peak of stars at 230 km/s is seen, consistent with
extended tidal debris from omega Centauri.Comment: accepted to A&
Stellar archaeology with Gaia: the Galactic white dwarf population
Gaia will identify several 1e5 white dwarfs, most of which will be in the
solar neighborhood at distances of a few hundred parsecs. Ground-based optical
follow-up spectroscopy of this sample of stellar remnants is essential to
unlock the enormous scientific potential it holds for our understanding of
stellar evolution, and the Galactic formation history of both stars and
planets.Comment: Summary of a talk at the 'Multi-Object Spectroscopy in the Next
Decade' conference in La Palma, March 2015, to be published in ASP Conference
Series (editors Ian Skillen & Scott Trager
Linear nonadiabatic properties of SX Phoenicis variables
We present a detailed linear, nonadiabatic pulsational scenario for
oscillating Blue Stragglers (BSs)/SX Phoenicis (SX Phe) in Galactic Globular
Clusters (GGCs) and in Local Group (LG) dwarf galaxies. The sequences of models
were constructed by adopting a wide range of input parameters and properly
cover the region of the HR diagram in which these objects are expected to be
pulsationally unstable. Current calculations together with more metal-rich
models already presented by Gilliland et al. suggest that the pulsation
properties of SX Phe are partially affected by metal content. Our calculations
also suggest that the secular period change seems to be a good observable to
identify the pulsation mode of cooler SX Phe variables. The dependence of
pulsation properties on the helium envelope content is discussed and we find
that the secular period change for He-enhanced models is approximately a factor
of two larger than for canonical ones. According to this evidence we suggest
that the pulsation properties of SX Phe can be soundly adopted to constrain the
evolutionary history of BSs, and in turn to single out the physical mechanisms
which trigger their formation.Comment: 25 pages, 9 postscript figures, 1 latex file containing five tables,
accepted for publication on Astrophysical Journa
Search for a new gauge boson in the Experiment (APEX)
We present a search at Jefferson Laboratory for new forces mediated by
sub-GeV vector bosons with weak coupling to electrons. Such a
particle can be produced in electron-nucleus fixed-target scattering and
then decay to an pair, producing a narrow resonance in the QED trident
spectrum. Using APEX test run data, we searched in the mass range 175--250 MeV,
found no evidence for an reaction, and set an upper limit of
. Our findings demonstrate that fixed-target
searches can explore a new, wide, and important range of masses and couplings
for sub-GeV forces.Comment: 5 pages, 5 figures, references adde
RR-Lyrae-type pulsations from a 0.26-solar-mass star in a binary system
RR Lyrae pulsating stars have been extensively used as tracers of old stellar
populations for the purpose of determining the ages of galaxies, and as tools
to measure distances to nearby galaxies. There was accordingly considerable
interest when the RR Lyr star OGLE-BLG-RRLYR-02792 was found to be a member in
an eclipsing binary system4, as the mass of the pulsator (hitherto constrained
only by models) could be unambiguously determined. Here we report that
RRLYR-02792 has a mass of 0.26 M_sun and therefore cannot be a classical RR
Lyrae star. Through models we find that its properties are best explained by
the evolution of a close binary system that started with 1.4 M_sun and 0.8
M_sun stars orbiting each other with an initial period of 2.9 days. Mass
exchange over 5.4 Gyr produced the observed system, which is now in a very
short-lived phase where the physical properties of the pulsator happen to place
it in the same instability strip of the H-R diagram occupied by RR Lyrae stars.
We estimate that samples of RR Lyr stars may contain a 0.2 percent
contamination with systems similar to this one, implying that distances
measured with RR Lyrae stars should not be significantly affected by these
binary interlopers
The Large Magellanic Cloud and the Distance Scale
The Magellanic Clouds, especially the Large Magellanic Cloud, are places
where multiple distance indicators can be compared with each other in a
straight-forward manner at considerable precision. We here review the distances
derived from Cepheids, Red Variables, RR Lyraes, Red Clump Stars and Eclipsing
Binaries, and show that the results from these distance indicators generally
agree to within their errors, and the distance modulus to the Large Magellanic
Cloud appears to be defined to 3% with a mean value of 18.48 mag, corresponding
to 49.7 Kpc. The utility of the Magellanic Clouds in constructing and testing
the distance scale will remain as we move into the era of Gaia.Comment: 23 pages, accepted for publication in Astrophysics and Space Science.
From a presentation at the conference The Fundamental Cosmic Distance Scale:
State of the Art and the Gaia Perspective, Naples, May 201
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