Immune-Complex Allergic Vasculitis in Association with the Immune-Complex Allergic Vasculitis in Association with the Development of Transverse Myelitis: A Case Report

A severe vasculitis, probably therapy related, in a sixty-four-year-old man being treated for possible subacute bacterial endocarditis, was associated with the development of transverse myelitis. It is hypothesized that the vasculitis affected the small vessels to the spinal cord in the same way that systemic vasculitis can also cause a transverse myelitis

Incipient ferroelectricity in 2.3% tensile-strained CaMnO3 films

Epitaxial CaMnO3 films grown with 2.3% tensile strain on (001)-oriented LaAlO3 substrates are found to be incipiently ferroelectric below 25 K. Optical second harmonic generation (SHG) was used for the detection of the incipient polarization. The SHG analysis reveals that CaMnO3 crystallites with in-plane orientation of the orthorhombic b axis contribute to an electric polarization oriented along the orthorhombic a (resp.\ c) axis in agreement with the predictions from density functional calculations

Existence of temperature on the nanoscale

We consider a regular chain of quantum particles with nearest neighbour interactions in a canonical state with temperature $T$. We analyse the conditions under which the state factors into a product of canonical density matrices with respect to groups of $n$ particles each and under which these groups have the same temperature $T$. In quantum mechanics the minimum group size $n_{min}$ depends on the temperature $T$, contrary to the classical case. We apply our analysis to a harmonic chain and find that $n_{min} = const.$ for temperatures above the Debye temperature and $n_{min} \propto T^{-3}$ below.Comment: Version that appeared in PR

Resonant cavity photon creation via the dynamical Casimir effect

Motivated by a recent proposal for an experimental verification of the dynamical Casimir effect, the macroscopic electromagnetic field within a perfect cavity containing a thin slab with a time-dependent dielectric permittivity is quantized in terms of the dual potentials. For the resonance case, the number of photons created out of the vacuum due to the dynamical Casimir effect is calculated for both polarizations (TE and TM). PACS: 42.50.Lc, 03.70.+k, 42.50.Dv, 42.60.Da.Comment: 4 pages, 1 figur

Neutrino-Mixing-Generated Lepton Asymmetry and the Primordial 4^4He Abundance

It has been proposed that an asymmetry in the electron neutrino sector may be generated by resonant active-sterile neutrino transformations during Big Bang Nucleosynthesis (BBN). We calculate the change in the primordial $^4$He yield $Y$ resulting from this asymmetry, taking into account both the time evolution of the $\nu_e$ and $\bar\nu_e$ distribution function and the spectral distortions in these. We calculate this change in two schemes: (1) a lepton asymmetry directly generated by $\nu_e$ mixing with a lighter right-handed sterile neutrino $\nu_s$; and (2) a lepton asymmetry generated by a $\nu_\tau\leftrightarrow\nu_s$ or $\nu_\mu\leftrightarrow\nu_s$ transformation which is subsequently partially converted to an asymmetry in the $\nu_e\bar\nu_e$ sector by a matter-enhanced active-active neutrino transformation. In the first scheme, we find that the percentage change in $Y$ is between -1% and 9% (with the sign depending on the sign of the asymmetry), bounded by the Majorana mass limit m_{\nu_e}\la 1 eV. In the second scheme, the maximal percentage reduction in $Y$ is 2%, if the lepton number asymmetry in neutrinos is positive; Otherwise, the percentage increase in $Y$ is \la 5% for m^2_{\nu_\mu,\nu_\tau}-m^2_{\nu_s}\la 10^4 eV. We conclude that the change in the primordial $^4$He yield induced by a neutrino-mixing-generated lepton number asymmetry can be substantial in the upward direction, but limited in the downward direction.Comment: 15 pages, 7 figures, submitted to PR

Non-Equilibrium Magnetization in a Ballistic Quantum Dot

We show that Aharonov-Bohm (AB) oscillations in the magnetic moment of an integrable ballistic quantum dot can be destroyed by a time dependent magnetic flux. The effect is due to a nonequilibrium population of perfectly coherent electronic states. For real ballistic systems the equilibrization process, which involves a special type of inelastic electron backscattering, can be so ineffective, that AB oscillations are suppressed when the flux varies with frequency $\omega\sim$ 10$^7$-10$^8$ s$^{-1}$. The effect can be used to measure relaxation times for inelastic backscattering.Comment: 11 pages LaTeX v3.14 with RevTeX v3.0, 3 post script figures available on request, APR 93-X2

A synthetic electric force acting on neutral atoms

Electromagnetism is a simple example of a gauge theory where the underlying potentials -- the vector and scalar potentials -- are defined only up to a gauge choice. The vector potential generates magnetic fields through its spatial variation and electric fields through its time-dependence. We experimentally produce a synthetic gauge field that emerges only at low energy in a rubidium Bose-Einstein condensate: the neutral atoms behave as charged particles do in the presence of a homogeneous effective vector potential. We have generated a synthetic electric field through the time dependence of an effective vector potential, a physical consequence even though the vector potential is spatially uniform

Semisimplicity of the quantum cohomology for smooth Fano toric varieties associated with facet symmetric polytopes

The degree zero part of the quantum cohomology algebra of a smooth Fano toric symplectic manifold is determined by the superpotential function, W, of its moment polytope. In particular, this algebra is semisimple, i.e. splits as a product of fields, if and only if all the critical points of W are non-degenerate. In this paper we prove that this non-degeneracy holds for all smooth Fano toric varieties with facet-symmetric duals to moment polytopes.Comment: 16 pages; corrected version, published in Electron. Res. Announc. Math. Sc