187 research outputs found
Fluctuation induced first order phase transition in thin films of type I superconductors
The effect of fluctuation induced weakly first order phase transition known
for three dimensional (3D) type I superconductors appears in a modified and
strongly enhanced variant in thin (quasi-2D) superconducting films. The unusual
thermodynamic properties of this new type of first order phase transitions and
the possibility for an experimental verification of the effect are established
and discussed
New features of the phase transition to superconducting state in thin films
The Halperin-Lubensky-Ma (HLM) effect of a fluctuation-induced change of the
order of phase transition in thin films of type I superconductors with
relatively small Ginzburg-Landau number is considered. Numerical data
for the free energy, the order parameter jump, the latent heat, and the
specific heat of W, Al and In are presented to reveal the influence of film
thickness and material parameters on the properties of the phase transition. We
demonstrate for the first time that in contrast to the usual notion the HLM
effect occurs in the most distinct way in superconducting films with high
critical magnetic field rather than in materials with small .
The possibility for an experimental observation of the fluctuation change of
the order of superconducting phase transition in superconducting films is
discussed.Comment: 11 pages, MikTexTeX, 3 fig, 2 Tables, corrected some typos, Submitted
J.Phys:Cond Ma
Effective spatial dimension of extremal non-dilatonic black p-branes and the description of entropy on the world volume
By investigating the critical behavior appearing at the extremal limit of the
non-dilatonic, black p-branes in (d+p) dimensions, we find that some critical
exponents related to the critical point obey the scaling laws. From the scaling
laws we obtain that the effective spatial dimension of the non-dilatonic black
holes and black strings is one, and is p for the non-dilatonic black p-branes.
For the dilatonic black holes and black p-branes, the effective dimension will
depend on the parameters in theories. Thus, we give an interpretation why the
Bekenstein-Hawking entropy may be given a simple world volume interpretation
only for the non-dilatonic black p-branes.Comment: 4 pages, RevTex, no figures, to appear in Phys. Rev. Let
Critical behavior in 2+1 dimensional black holes
The critical behavior and phase transition in the 2+1 dimensional Ba\~nados,
Teitelboim, and Zanelli (BTZ) black holes are discussed. By calculating the
equilibrium thermodynamic fluctuations in the microcanonical ensemble,
canonical ensemble, and grand canonical ensemble, respectively, we find that
the extremal spinning BTZ black hole is a critical point, some critical
exponents satisfy the scaling laws of the ``first kind'', and the scaling laws
related to the correlation length suggest that the effective spatial dimension
of extremal black holes is one, which is in agreement with the argument that
the extremal black holes are the Bogomol'nyi saturated string states. In
addition, we find that the massless BTZ black hole is a critical point of
spinless BTZ black holes.Comment: RevTex, 9 pages, nofigur
Global and Regional IUCN Red List Assessments: 2
In this contribution the conservation status assessment of six plant species according to IUCN categories and criteria are presented. It includes the assessment at global level of Charybdis glaucophylla Bacch., Brullo, D'Emerico, Pontec. & Salmeri, Euphorbia nicaeensis All. subsp. japygica (Ten.) Arcang., Hieracium australe Fr. subsp. australe, Limonium multiforme Pignatti, Onosma helvetica Boiss. em. Teppner subsp. lucana (Lacaita) Peruzzi, Aquaro & Cesca and the assessment at national level (Italy) of Lathyrus laxiflorus (Desf.) Kuntze subsp. laxiflorus
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