1,550 research outputs found
Non-Linear Realisation of the Pure N=4, D=5 Supergravity
We perform the non-linear realisation or the coset formulation of the pure
N=4, D=5 supergravity. We derive the Lie superalgebra which parameterizes a
coset map whose induced Cartan-Maurer form produces the bosonic field equations
of the pure N=4, D=5 supergravity by canonically satisfying the Cartan-Maurer
equation. We also obtain the first-order field equations of the theory as a
twisted self-duality condition for the Cartan-Maurer form within the
geometrical framework of the coset construction.Comment: 12 page
Eigenfunctions of the Laplacian and associated Ruelle operator
Let be a co-compact Fuchsian group of isometries on the Poincar\'e
disk \DD and the corresponding hyperbolic Laplace operator. Any
smooth eigenfunction of , equivariant by with real
eigenvalue , where , admits an integral
representation by a distribution \dd_{f,s} (the Helgason distribution) which
is equivariant by and supported at infinity \partial\DD=\SS^1. The
geodesic flow on the compact surface \DD/\Gamma is conjugate to a suspension
over a natural extension of a piecewise analytic map T:\SS^1\to\SS^1, the
so-called Bowen-Series transformation. Let be the complex Ruelle
transfer operator associated to the jacobian . M. Pollicott showed
that \dd_{f,s} is an eigenfunction of the dual operator for the
eigenvalue 1. Here we show the existence of a (nonzero) piecewise real analytic
eigenfunction of for the eigenvalue 1, given by an
integral formula \psi_{f,s} (\xi)=\int \frac{J(\xi,\eta)}{|\xi-\eta|^{2s}}
\dd_{f,s} (d\eta), \noindent where is a -valued
piecewise constant function whose definition depends upon the geometry of the
Dirichlet fundamental domain representing the surface \DD/\Gamma
Measuring patchy reionisation with kSZ-21 cm correlations
We study cross-correlations of the kinetic Sunyaev-Zel'dovich effect (kSZ)
and 21 cm signals during the epoch of reionisation (EoR) to measure the effects
of patchy reionisation. Since the kSZ effect is proportional to the
line-of-sight velocity, the kSZ-21 cm cross correlation suffers from
cancellation at small angular scales. We thus focus on the correlation between
the kSZ-squared field (kSZ) and 21 cm signals. When the global ionisation
fraction is low (), the kSZ fluctuation is dominated by
rare ionised bubbles which leads to an anti-correlation with the 21 cm signal.
When , the correlation is dominated by small pockets of
neutral regions, leading to a positive correlation. However, at very high
redshifts when , the spin temperature fluctuations change the sign of
the correlation from negative to positive, as weakly ionised regions can have
strong 21 cm signals in this case. To extract this correlation, we find that
Wiener filtering is effective in removing large signals from the primary CMB
anisotropy. The expected signal-to-noise ratios for a 10-hour integration
of upcoming Square Kilometer Array data cross-correlated with maps from the
current generation of CMB observatories with 3.4~K arcmin noise and
1.7~arcmin beam over 100~deg are 51, 60, and 37 for , 0.5, and
0.9, respectively.Comment: 7pages, 7 figure
Operator Product on Locally Symmetric Spaces of Rank One and the Multiplicative Anomaly
The global multiplicative properties of Laplace type operators acting on
irreducible rank one symmetric spaces are considered. The explicit form of the
multiplicative anomaly is derived and its corresponding value is calculated
exactly, for important classes of locally symmetric spaces and different
dimensions.Comment: Int. Journal of Modern Physics A, vol. 18 (2003), 2179-218
Medical concepts related to individual risk are better explained with "plausibility" rather than "probability"
BACKGROUND: The concept of risk has pervaded medical literature in the last decades and has become a familiar topic, and the concept of probability, linked to binary logic approach, is commonly applied in epidemiology and clinical medicine. The application of probability theory to groups of individuals is quite straightforward but can pose communication challenges at individual level. Few articles by the way have tried to focus the concept of "risk" at the individual subject level rather than at population level. DISCUSSION: The author has reviewed the conceptual framework which has led to the use of probability theory in the medical field in a time when the principal causes of death were represented by acute disease often of infective origin. In the present scenario, in which chronic degenerative disease dominate and there are smooth transitions between health and disease the use of fuzzy logic rather than binary logic would be more appropriate. The use of fuzzy logic in which more than two possible truth-value assignments are allowed overcomes the trap of probability theory when dealing with uncertain outcomes, thereby making the meaning of a certain prognostic statement easier to understand by the patient. SUMMARY: At individual subject level the recourse to the term plausibility, related to fuzzy logic, would help the physician to communicate to the patient more efficiently in comparison with the term probability, related to binary logic. This would represent an evident advantage for the transfer of medical evidences to individual subjects
Connecting geodesics and security of configurations in compact locally symmetric spaces
A pair of points in a riemannian manifold makes a secure configuration if the
totality of geodesics connecting them can be blocked by a finite set. The
manifold is secure if every configuration is secure. We investigate the
security of compact, locally symmetric spaces.Comment: 27 pages, 2 figure
Dualisation of the D=9 Matter Coupled Supergravity
We perform the bosonic dualisation of the matter coupled N=1, D=9
supergravity. We derive the Lie superalgebra which parameterizes the coset map
whose Cartan form realizes the second-order bosonic field equations. Following
the non-linear coset construction we present the first-order formulation of the
bosonic field equations as a twisted self-duality condition.Comment: 16 page
Treating tobacco addiction. Praxis and barriers amongst Icelandic general practitioners
Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenObjective: To assess praxis and identify the most common barriers for engaging in tobacco prevention in general practice in the Nordic countries. Material and methods: All 167 practicing general practitioners in Iceland received a questionnaire at home assessing praxis and barriers for systematic involvement in tobacco prevention. Results: The over all response rate was 77%. Few general practitioners asked patients if they smoked if the patient had no smoking related symptoms. Few supported patients who wanted to stop smoking. However, a big majority agreed that tobacco prevention was a part of their job. The main reasons for not engaging in tobacco prevention was lack of time and the feeling that the time spent may not be worth the effort since few patients quit. A big majority stated that they would prefer to reefer smokers to smoking cessation specialist. Conclusions: Smoking cessation expertise needs to be more accessible to Icelandic patients and doctors.Tilgangur: Að kanna meðferðarvenjur heilsugæslulækna við meðhöndlun á tóbaksfíkn og greina helstu þröskulda (hindranir) sem standa í vegi fyrir því að heilsugæslulæknar á Íslandi sinni tóbaksvörnum. Efniviður og aðferðir: Spurningalisti var sendur heim til allra 167 starfandi heilsugæslulækna á Íslandi vorið 1999. Spurt var um tóbaksvarnastarf, hindranir fyrir að sinna tóbaksvörnum og eigin tóbaksneyslu heilsugæslulækna. Niðurstöður: Svarshlutfall var 77%. Af þeim sem svöruðu reyktu 7% daglega og 14% af og til. Fáir heilsugæslulæknar höfðu það sem reglu að spyrja sjúklinga sín hvort þeir reyktu ef þeir höfðu engin einkenni sem líklegt er að rekja megi til reykinga. Fáir buðu sjúklingum sínum upp á stuðning við að hætta að reykja. Flestir töldu tóbaksvarnir þó vera innan síns verksviðs. Aðalástæðan fyrir að sinna ekki tóbaksvörnum var tímaskortur og sú tilfinning að fáir hætti að reykja þrátt fyrir stuðning. Mikill meirihluti taldi æskilegt að geta vísað reykingamönnum til sérfræðinga í reykbindindi. Ályktanir: Auka þarf aðgengi sjúklinga og heilsugæslulækna að sérfræðingum í reykbindindi
Extremal Black Attractors in 8D Maximal Supergravity
Motivated by the new higher D-supergravity solutions on intersecting
attractors obtained by Ferrara et al. in [Phys.Rev.D79:065031-2009], we focus
in this paper on 8D maximal supergravity with moduli space
[SL(3,R)/SO(3)]x[SL(2,R)/SO(2)] and study explicitly the attractor mechanism
for various configurations of extremal black p- branes (anti-branes) with the
typical near horizon geometries AdS_{p+2}xS^{m}xT^{6-p-m} and p=0,1,2,3,4;
2<=m<=6. Interpretations in terms of wrapped M2 and M5 branes of the 11D
M-theory on 3-torus are also given.
Keywords: 8D supergravity, black p-branes, attractor mechanism, M-theory.Comment: 37 page
Representations of the -algebra and the loop representation in -dimensions
We consider the phase-space of Yang-Mills on a cylindrical space-time () and the associated algebra of gauge-invariant functions, the
-variables. We solve the Mandelstam identities both classically and
quantum-mechanically by considering the -variables as functions of the
eigenvalues of the holonomy and their associated momenta. It is shown that
there are two inequivalent representations of the quantum -algebra. Then we
compare this reduced phase space approach to Dirac quantization and find it to
give essentially equivalent results. We proceed to define a loop representation
in each of these two cases. One of these loop representations (for ) is
more or less equivalent to the usual loop representation.Comment: 15 pages, LaTeX, 1 postscript figure included, uses epsf.sty,
G\"oteborg ITP 93-3
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