121,997 research outputs found
Statistics of Mesoscopic Fluctuations of Quantum Capacitance
The Thouless formula for the two-probe dc
conductance of a d-dimensional mesoscopic cube is re-analysed to relate its
quantum capacitance to the reciprocal of the level spacing . To
this end, the escape time-scale occurring in the Thouless correlation
energy is interpreted as the {\em time constant} with 1, giving at once . Thus,
the statistics of the quantum capacitance is directly related to that of the
level spacing, which is well known from the Random Matrix Theory for all the
three universality classes of statistical ensembles. The basic questions of how
intrinsic this quantum capacitance can arise purely quantum-resistively, and of
its observability {\em vis-a-vis} the external geometric capacitance that
combines with it in series, are discussed
Fractional Power-Law Spectral Response of CaCu3Ti4O12 Dielectric: Many-Body Effects
Spectral character of dielectric response in CaCu3Ti4O12 across 0.5Hz-4MHz
over 45-200K corresponding to neither the Debyean nor the KWW relaxation
patterns rather indicates a random-walk like diffusive dynamics of moments.
Non-linear relaxation here is due to the many body dipole-interactions, as
confirmed by spectral-fits of our measured permittivity to the Dissado-Hill
behaviour. Fractional power-laws observed in {\epsilon}*({\omega})
macroscopically reflect the fractal microscopic configurations. Below ~100K,
the power-law exponent m (n) steeply decreases (increases), indicating finite
length-scale collective response of moment-bearing entities. At higher
temperatures, m gradually approaches 1 and n falls to low values, reflecting
tendency towards the single-particle/Debyean relaxation.Comment: 10 pages, 3 figures, 22 reference
Strings, Junctions and Stability
Identification of string junction states of pure SU(2) Seiberg-Witten theory
as B-branes wrapped on a Calabi-Yau manifold in the geometric engineering limit
is discussed. The wrapped branes are known to correspond to objects in the
bounded derived category of coherent sheaves on the projective line \cp{1} in
this limit. We identify the pronged strings with triangles in the underlying
triangulated category using Pi-stability. The spiral strings in the weak
coupling region are interpreted as certain projective resolutions of the
invertible sheaves. We discuss transitions between the spiral strings and
junctions using the grade introduced for Pi-stability through the central
charges of the corresponding objects.Comment: 15 pages, LaTeX; references added. typos correcte
Lagrangian and Hamiltonian formulations of higher order Chern-Simons theories
We consider models involving the higher (third) derivative extension of the
abelian Chern-Simons (CS) topological term in D=2+1 dimensions. The
polarisation vectors in these models reveal an identical structure with the
corresponding expressions for usual models which contain, at most, quadratic
structures. We also investigate the Hamiltonian structure of these models and
show how Wigner's little group acts as gauge generator.Comment: 13 pages, Late
An interesting case of suicidal poisoning
Aconite is one of the most poisonous known herbs. It has been known to be used as a homicidal poison from long time in history. However this is rarely known to be used as suicidal poison. Poisoning with aconite is usually fatal and death commonly occurs due to arrhythmias and cardiotoxicity. We report a case of attempted suicidal poisoning by aconite where patient survived in spite of documented cardiotoxic effects of the poison
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