1,526 research outputs found
Fundamental Strings in Open String Theory at the Tachyonic Vacuum
We show that the world-volume theory on a D-p-brane at the tachyonic vacuum
has solitonic string solutions whose dynamics is governed by the Nambu-Goto
action of a string moving in (25+1) dimensional space-time. This provides
strong evidence for the conjecture that at this vacuum the full (25+1)
dimensional Poincare invariance is restored. We also use this result to argue
that the open string field theory at the tachyonic vacuum must contain closed
string excitations.Comment: LaTeX file, 16 pages, references and clarification adde
Two-Dimensional Dilaton-Gravity Coupled to Massless Spinors
We apply a global and geometrically well-defined formalism for
spinor-dilaton-gravity to two-dimensional manifolds. We discuss the general
formalism and focus attention on some particular choices of the dilatonic
potential. For constant dilatonic potential the model turns out to be
completely solvable and the general solution is found. For linear and
exponential dilatonic potentials we present the class of exact solutions with a
Killing vector.Comment: 21 pages, LaTeX, minor changes in text and format, final version to
appear in Classical and Quantum Gravit
Nutritive value and chemical composition of certain fresh-water plants of Minnesota
This archival publication may not reflect current scientific knowledge or recommendations
Constraining the source regions of lunar meteorites using orbital geochemical data
Lunar meteorites provide important new samples of the Moon remote from regions visited by the Apollo and Luna sample return missions. Petrologic and geochemical analysis of these meteorites, combined with orbital remote-sensing measurements have enabled additional discoveries about the composition and age of the lunar surface on a global scale. However, the interpretation of these samples is limited by the fact that we do not know the source region of any individual lunar meteorite. Here we investigate the link between meteorite and source region on the Moon using the Lunar Prospector Gamma Ray Spectrometer remote sensing dataset for the elements Fe, Ti and Th. The approach has been validated using Apollo and Luna bulk regolith samples and we have applied it to 48 meteorites excluding paired stones. Our approach is able broadly to differentiate the best compositional matches as potential regions of origin for the various classes of lunar meteorites. Basaltic and intermediate-Fe regolith breccia meteorites are found to have the best constrained potential launch sites, with some impact breccias and pristine mare basalts also having reasonably well defined potential source regions. Launch areas for highland feldspathic meteorites are much less well constrained and the addition of another element, such as Mg, will probably be required to identify potential source regions for these
Institutional trust and alcohol consumption in Sweden: The Swedish National Public Health Survey 2006
<p>Abstract</p> <p>Background</p> <p>Trust as a measure of social capital has been documented to be associated with health. Mediating factors for this association are not well investigated. Harmful alcohol consumption is believed to be one of the mediating factors. We hypothesized that low social capital defined as low institutional trust is associated with harmful alcohol consumption.</p> <p>Methods</p> <p>Data from the 2006 Swedish National Survey of Public Health were used for analyses. The total study population comprised a randomly selected representative sample of 26.305 men and 30.584 women aged 16–84 years. Harmful alcohol consumption was measured using a short version the Alcohol Use Disorders Identification Test (AUDIT), developed and recommended by the World Health Organisation. Low institutional trust was defined based on trust in ten main welfare institutions in Sweden.</p> <p>Results</p> <p>Independent of age, country of birth and socioeconomic circumstances, low institutional trust was associated with increased likelihood of harmful alcohol consumption (OR (men) = 1.52, 95% CI 1.34–1.70) and (OR (women) = 1.50, 95% CI 1.35–1.66). This association was marginally altered after adjustment for interpersonal trust.</p> <p>Conclusion</p> <p>Findings of the present study show that lack of trust in institutions is associated with increased likelihood of harmful alcohol consumption. We hope that findings in the present study will inspire similar studies in other contexts and contribute to more knowledge on the association between institutional trust and lifestyle patterns. This evidence may contribute to policies and strategies related to alcohol consumption.</p
The Influence of the Second Harmonic in the Current-Phase Relation on the Voltage-Current Characteristic of high TC DC SQUID
A theory for the voltage-current characteristic in high TC DC SQUIDs, which
accounts for a second harmonic in the junction current-phase relation, is
developed. The comparison with experiment is performed. It is shown that if the
second harmonic is prevailed, the theory can explain the large deviations of
the experimental voltage modulation from theoretical predictions and computer
simulations based on conventional sinusoidal current-phase relation.Comment: Eq. 13 is correcte
From Vicious Walkers to TASEP
We propose a model of semi-vicious walkers, which interpolates between the
totally asymmetric simple exclusion process and the vicious walkers model,
having the two as limiting cases. For this model we calculate the asymptotics
of the survival probability for particles and obtain a scaling function,
which describes the transition from one limiting case to another. Then, we use
a fluctuation-dissipation relation allowing us to reinterpret the result as the
particle current generating function in the totally asymmetric simple exclusion
process. Thus we obtain the particle current distribution asymptotically in the
large time limit as the number of particles is fixed. The results apply to the
large deviation scale as well as to the diffusive scale. In the latter we
obtain a new universal distribution, which has a skew non-Gaussian form. For
particles its asymptotic behavior is shown to be
as and
as .Comment: 37 pages, 4 figures, Corrected reference
Dirac-Born-Infeld Action on the Tachyon Kink and Vortex
The tachyon effective field theory describing the dynamics of a non-BPS
D-brane in superstring theory has an infinitely thin but finite tension kink
solution describing a codimension one BPS D-brane. We study the world-volume
theory of massless modes on the kink, and show that the world volume action has
precisely the Dirac-Born-Infeld (DBI) form without any higher derivative
corrections. We generalize this to a vortex solution in the effective field
theory on a brane-antibrane pair. As in the case of the kink, the vortex is
infinitely thin, has finite energy density, and the world-volume action on the
vortex is again given exactly by the DBI action on a BPS D-brane. We also
discuss the coupling of fermions and restoration of supersymmetry and
-symmetry on the world-volume of the kink. Absence of higher derivative
corrections to the DBI action on the soliton implies that all such corrections
are related to higher derivative corrections to the original effective action
on the world-volume of a non-BPS D-brane or brane-antibrane pair.Comment: LaTeX file, 34 pages; references and other minor comments adde
Multi-Jet Event Rates in Deep Inelastic Scattering and Determination of the Strong Coupling Constant
Jet event rates in deep inelastic ep scattering at HERA are investigated
applying the modified JADE jet algorithm. The analysis uses data taken with the
H1 detector in 1994 and 1995. The data are corrected for detector and
hadronization effects and then compared with perturbative QCD predictions using
next-to-leading order calculations. The strong coupling constant alpha_S(M_Z^2)
is determined evaluating the jet event rates. Values of alpha_S(Q^2) are
extracted in four different bins of the negative squared momentum
transfer~\qq in the range from 40 GeV2 to 4000 GeV2. A combined fit of the
renormalization group equation to these several alpha_S(Q^2) values results in
alpha_S(M_Z^2) = 0.117+-0.003(stat)+0.009-0.013(syst)+0.006(jet algorithm).Comment: 17 pages, 4 figures, 3 tables, this version to appear in Eur. Phys.
J.; it replaces first posted hep-ex/9807019 which had incorrect figure 4
Energy Flow in the Hadronic Final State of Diffractive and Non-Diffractive Deep-Inelastic Scattering at HERA
An investigation of the hadronic final state in diffractive and
non--diffractive deep--inelastic electron--proton scattering at HERA is
presented, where diffractive data are selected experimentally by demanding a
large gap in pseudo --rapidity around the proton remnant direction. The
transverse energy flow in the hadronic final state is evaluated using a set of
estimators which quantify topological properties. Using available Monte Carlo
QCD calculations, it is demonstrated that the final state in diffractive DIS
exhibits the features expected if the interaction is interpreted as the
scattering of an electron off a current quark with associated effects of
perturbative QCD. A model in which deep--inelastic diffraction is taken to be
the exchange of a pomeron with partonic structure is found to reproduce the
measurements well. Models for deep--inelastic scattering, in which a
sizeable diffractive contribution is present because of non--perturbative
effects in the production of the hadronic final state, reproduce the general
tendencies of the data but in all give a worse description.Comment: 22 pages, latex, 6 Figures appended as uuencoded fil
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