9,293 research outputs found
The Scottish adolescent e-cigarette user : profiling from the Scottish Adolescent Lifestyle and Substance Use Survey (SALSUS)
Objectives: Profiling the Scottish adolescent e-cigarette user Study design: 283 state, independent and grant maintained schools participated in the Scottish Adolescent Lifestyle and Substance Use Survey (SALSUS) between September 2013 and 2014. 33,685 13 and 15-year-old pupils who had completed the cross-sectional survey SALSUS questionnaire, and answered the question based on e-cigarette use were included in the analysis. Profiling of the typical Scottish adolescent e-cigarette user through gender, age, socioeconomic status, urban/rural location, weekly alcohol consumption, current drug use and current tobacco smoking was the main outcome measured. Results: 1.1% of adolescents were current e-cigarette users with 11% having tried the devices before. Current e-cigarette users were significantly more likely to be male (OR=1.9; CI= 1.5-1.9), rural (OR= 1.4; CI=1.1-1.9), smoke tobacco (OR=21.1; CI=15.3-29.1), weekly alcohol (OR=1.4; CI=1.1-1.9) and current drug users (OR=2.3; CI=1.7-3.0). There were no significance differences observed for socioeconomic status. Similar results were observed for those using both and those who only used e-cigarettes. Only tobacco smokers differed in that they were significantly more likely to be female than male (OR=0.56; CI=0.51-0.63) and of a lower socioeconomic status (OR=1.3; CI=1.1-1.4). Conclusions: The Scottish adolescent e-cigarette user is male, lives rurally, a weekly alcohol drinker, a current drug user and a tobacco smoker. This profiling study helps to inform policy makers targeting e-cigarette use. Further research requires a longitudinal study and monitoring the changing views of this group.PostprintPeer reviewe
Valence Bond Entanglement and Fluctuations in Random Singlet Phases
The ground state of the uniform antiferromagnetic spin-1/2 Heisenberg chain
can be viewed as a strongly fluctuating liquid of valence bonds, while in
disordered chains these bonds lock into random singlet states on long length
scales. We show that this phenomenon can be studied numerically, even in the
case of weak disorder, by calculating the mean value of the number of valence
bonds leaving a block of contiguous spins (the valence-bond entanglement
entropy) as well as the fluctuations in this number. These fluctuations show a
clear crossover from a small regime, in which they behave similar to those
of the uniform model, to a large regime in which they saturate in a way
consistent with the formation of a random singlet state on long length scales.
A scaling analysis of these fluctuations is used to study the dependence on
disorder strength of the length scale characterizing the crossover between
these two regimes. Results are obtained for a class of models which include, in
addition to the spin-1/2 Heisenberg chain, the uniform and disordered critical
1D transverse-field Ising model and chains of interacting non-Abelian anyons.Comment: 8 pages, 6 figure
Helicopter approach capability using the differential Global Positioning System
The results of flight tests to determine the feasibility of using the Global Positioning System (GPS) in the differential mode (DGPS) to provide high accuracy, precision navigation and guidance for helicopter approaches to landing are presented. The airborne DGPS receiver and associated equipment is installed in a NASA UH-60 Black Hawk helicopter. The ground-based DGPS reference receiver is located at a surveyed test site and is equipped with a real-time VHF data link to transmit correction information to the airborne DGPS receiver. The corrected airborne DGPS information, together with the preset approach geometry, is used to calculate guidance commands which are sent to the aircraft's approach guidance instruments. The use of DGPS derived guidance for helicopter approaches to landing is evaluated by comparing the DGPS data with the laser tracker truth data. Both standard (3 degrees) and steep (6 degrees and 9 degrees) glidescope straight-in approaches were flown. DGPS positioning accuracy based on a time history analysis of the entire approach was 0.2 m (mean) +/- 1.8 m (2 sigma) laterally and -2.0 m (mean) +/- 3.5 m (2 sigma) vertically for 3 degree glidescope approaches, -0.1 m (mean) +/- 1.5 m (2 sigma) laterally and -1.1 m (mean) +/- 3.5 m (2 sigma) vertically for 6 degree glidescope approaches, and 0.2 m (mean) +/- 1.3 m (2 sigma) laterally and -1.0 m (mean) +/- 2.8 (2 sigma) vertically for 9 degree glidescope approaches. DGPS positioning accuracy at the 200 ft decision height on a standard 3 degree glidescope approach was 0.3 m (mean) +/- 1.5 m (2 sigma) laterally and -2.3 m (mean) +/- 1.6 m (2 sigma) vertically. These errors indicate that the helicopter position based on DGPS guidance satisfies the International Civil Aviation Organization Category 1 lateral and vertical accuracy requirements
Helicopter precision approach capability using the Global Positioning System
The period between 1 July and 31 December, 1992, was spent developing a research plan as well as a navigation system document and flight test plan to investigate helicopter precision approach capability using the Global Positioning System (GPS). In addition, all hardware and software required for the research was acquired, developed, installed, and verified on both the test aircraft and the ground-based reference station
Diamonds are Forever
We defend the thesis that every necessarily true proposition is always true. Since not every proposition that is always true is necessarily true, our thesis is at odds with theories of modality and time, such as those of Kit Fine and David Kaplan, which posit a fundamental symmetry between modal and tense operators. According to such theories, just as it is a contingent matter what is true at a given time, it is likewise a temporary matter what is true at a given possible world; so a proposition that is now true at all worlds, and thus necessarily true, may yet at some past or future time be false in the actual world, and thus not always true. We reconstruct and criticize several lines of argument in favor of this picture, and then argue against the picture on the grounds that it is inconsistent with certain sorts of contingency in the structure of time
HESS J1507-622: an unique unidentified source off the Galactic Plane
Galactic very high energy (VHE, > 100 GeV) gamma ray sources in the inner
Galaxy H.E.S.S. survey tend to cluster within 1 degree in latitude around the
Galactic plane. HESS J1507-622 instead is unique, since it is located at
latitude of ~3.5 degrees. HESS J1507-622 is slightly extended over the PSF of
the instrument and hence its Galactic origin is clear. The search for
counterparts in other wavelength regimes (radio, infrared and X-rays) failed to
show any plausible counterparts; and given its position off the Galactic plane
and hence the absorption almost one order of magnitude lower, it is very
surprising to not see any counterparts especially at X-rays wavelengths (by
ROSAT, XMM Newton and Chandra). Its latitude implies that it is either rather
close, within about 1 kpc, or is located well off the Galactic plane. And also
the models reflect the uniqueness of this object: a leptonic PWN scenario would
place this source due to its quite small extension to multi-kpc distance
whereas a hadronic scenario would preferentially locate this object at
distances of < 1 kpc where the density of target material is higher
Infinite-Randomness Fixed Points for Chains of Non-Abelian Quasiparticles
One-dimensional chains of non-Abelian quasiparticles described by
Chern-Simons-Witten theory can enter random singlet phases analogous to that of
a random chain of ordinary spin-1/2 particles (corresponding to ). For this phase provides a random singlet description of the
infinite randomness fixed point of the critical transverse field Ising model.
The entanglement entropy of a region of size in these phases scales as for large , where is the quantum
dimension of the particles.Comment: 4 pages, 4 figure
FINE STRUCTURE OF CHROMOSOMES
Electron micrographs of staminate hair cells of Tradescantia reflexa indicate that early prophase chromosomes are composed of a number of helically arranged chromonemata. Favorable preparations reveal as many as 64 identifiable subsidiary strands, assumedly arranged as intertwined pairs to form a hierarchy of pairs of pairs. The helices of the smallest discernible units have a diameter of about 125 A, with highly electron-scattering material disposed peripherally around a less dense "core." The wall of this peripheral ring has a thickness of about 40 A, and apparently represents another pair of coiled threads surrounding a 40 A central axis. The implications of the findings are discussed briefly
Non-equilibrium Relaxation Study of Ferromagnetic Transition in Double-Exchange Systems
Ferromagnetic transition in double-exchange systems is studied by
non-equilibrium relaxation technique combined with Monte Carlo calculations.
Critical temperature and critical exponents are estimated from relaxation of
the magnetic moment. The results are consistent with the previous Monte Carlo
results in thermal equilibrium. The exponents estimated by these independent
techniques suggest that the universality class of this transition is the same
as that of short-range interaction models but is different from the mean-field
one.Comment: 3 pages including 1 figure, submitted to J. Phys. Soc. Jp
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