Landau-Stark states and cyclotron-Bloch oscillations of a quantum particle

Recent experimental progress in the creation of synthetic electric and magnetic fields, acting on cold atoms in a two-dimensional lattice, has attracted renewed interest to the problem of a quantum particle in the Hall configuration. The present work contains a detailed analysis of the eigenstates of this system, called Landau-Stark states, and of the associated dynamical phenomenon of cyclotron-Bloch oscillations. It is shown that Landau-Stark states and cyclotron-Bloch oscillations crucially depend on two factors. The first is the orientation of the electric field relative to the primary axes of the lattice. The second is ratio between the frequencies of Bloch and cyclotron oscillations, that is also the ratio between the magnitudes of electric and magnetic fields. The analysis is first carried out in the tight-binding approximation, where the magnetic field is characterized by the Peierls phase entering the hopping matrix elements. Agreement of this analysis with the full quantum theory is also studied.Comment: 39 pages, 26 figure

Can unilateral, progressive or sudden hearing loss be immune-mediated in origin?

OBJECTIVE: The aim of the present study was to demonstrate that the positivity of nonspecific immunological tests could be found not only in bilateral hearing loss but also in unilateral cases, either sudden or progressive. METHOD: An observational case series study included subjects suffering from unilateral or bilateral, sudden or progressive, symmetric or asymmetric sensorineural hearing loss (SNHL). All the patients underwent pure tone audiometry and the following battery of blood exams: anti-nuclear antibody (ANA), extractable nuclear antigen (ENA) antibody screening, anti-thyroperoxidase (anti-TPO), anti-thyroglobulin and anti-smooth muscle antibody (ASMA). RESULTS: The positivity to nonspecific immunological test was found in nearly 70% of the study groups. ASMA and ANA were found to be present in both bilateral and unilateral cases, without statistical difference. Considering the correlation between positivity/negativity and systemic autoimmune pathologies, in the bilateral forms of hearing loss, a high incidence of thyroid pathologies has been identified, with a higher percentage of systemic autoimmune diseases in respect to the normal population. CONCLUSIONS: The nonspecific autoimmune tests are worth to be performed also when SNHL is not bilateral and progressive, since an immunological mechanism could also underlie unilateral and sudden SNHL cases

Instability of Boost-invariant hydrodynamics with a QCD inspired bulk viscosity

We solve the relativistic Navier-Stokes equations with homogeneous boost-invariant boundary conditions, and perform a stability analysis of the solution. We show that, if the bulk viscosity has a peak around $T_c$ as inferred from QCD-based arguments, the background solution "freezes" at $T_c$ to a nearly constant temperature state. This state is however highly unstable with respect to certain inhomogeneous modes. Calculations show that these modes have enough time to blow up and tear the system into droplets. We conjecture that this is how freeze-out occurs in the QGP created in heavy ion collisions, and perhaps similar transitions in the early universe.Comment: Accepted for publication, Rapid Communication in Physical Review C Discussion extended, derivation and conclusions not change

Relaxation of Chemical Reactions to Stationary States in the Chemical Affinities Space

Using the mass balance equations for chemical reactions, we show how the system relaxes towards a steady state in and out of the Onsager region. In the chemical affinities space, after fast transients, the relaxation process is a straight line when operating in the Onsager region, while out of this regime, the evolution of the system is such that the projections of the evolution equations for the forces and the shortest path on the flows coincide. For spatially-extended systems, similar results are valid for the evolution of the thermodynamic mode (i.e., the mode with wave-number k = 0). These results allow us to obtain the expression for the affine connection of the space covered by the thermodynamic forces, close to the steady states. Through the affine connection, the nonlinear closure equations are derived.Comment: 23 pages

The Euclidean distance degree of an algebraic variety

The nearest point map of a real algebraic variety with respect to Euclidean distance is an algebraic function. For instance, for varieties of low rank matrices, the Eckart-Young Theorem states that this map is given by the singular value decomposition. This article develops a theory of such nearest point maps from the perspective of computational algebraic geometry. The Euclidean distance degree of a variety is the number of critical points of the squared distance to a generic point outside the variety. Focusing on varieties seen in applications, we present numerous tools for exact computations.Comment: to appear in Foundations of Computational Mathematic

Monte Carlo Update for Chain Molecules: Biased Gaussian Steps in Torsional Space

We develop a new elementary move for simulations of polymer chains in torsion angle space. The method is flexible and easy to implement. Tentative updates are drawn from a (conformation-dependent) Gaussian distribution that favors approximately local deformations of the chain. The degree of bias is controlled by a parameter b. The method is tested on a reduced model protein with 54 amino acids and the Ramachandran torsion angles as its only degrees of freedom, for different b. Without excessive fine tuning, we find that the effective step size can be increased by a factor of three compared to the unbiased b=0 case. The method may be useful for kinetic studies, too.Comment: 14 pages, 4 figure

Randomizing world trade. II. A weighted network analysis

Based on the misleading expectation that weighted network properties always offer a more complete description than purely topological ones, current economic models of the International Trade Network (ITN) generally aim at explaining local weighted properties, not local binary ones. Here we complement our analysis of the binary projections of the ITN by considering its weighted representations. We show that, unlike the binary case, all possible weighted representations of the ITN (directed/undirected, aggregated/disaggregated) cannot be traced back to local country-specific properties, which are therefore of limited informativeness. Our two papers show that traditional macroeconomic approaches systematically fail to capture the key properties of the ITN. In the binary case, they do not focus on the degree sequence and hence cannot characterize or replicate higher-order properties. In the weighted case, they generally focus on the strength sequence, but the knowledge of the latter is not enough in order to understand or reproduce indirect effects.Comment: See also the companion paper (Part I): arXiv:1103.1243 [physics.soc-ph], published as Phys. Rev. E 84, 046117 (2011

Anomalous vortex ring velocities induced by thermally-excited Kelvin waves and counterflow effects in superfluids

Dynamical counterflow effects on vortex evolution under the truncated Gross-Pitaevskii equation are investigated. Standard longitudinal mutual friction effects are produced and a dilatation of vortex rings is obtained at large counterflow. A strong temperature-dependent anomalous slowdown of vortex rings is observed and attributed to the presence of thermally exited Kelvin waves. This generic effect of finite-temperature superfluids is estimated using energy equipartition and orders of magnitude are given for weakly interacting Bose-Einstein condensates and superfluid $^4{\rm He}$

Jevic\u27s Minimal Impact on Structured Dismissals and Bankruptcy Sales

(Excerpt) Recently, courts have been confronted with issues concerning the permissibility of structured dismissals and bankruptcy sales in a way they had not before. In general, a successful case under Chapter 11 of title 11 of the United States Code (the Bankruptcy Code ) culminates in a confirmation of a plan of reorganization, pursuant to which the debtor\u27s liabilities will be addressed. In certain instances, confirmation of a plan may be impossible or cost-prohibitive, but the debtor and its creditors have achieved a consensus regarding the treatment of the debtor\u27s liabilities. There, the debtor and its creditors may agree to the treatment of claims, following which the case will be dismissed through a structured dismissal. While there are magic words in the Bankruptcy Code that allow for structured dismissals, [n]ot much law, statutorily or otherwise, exists regarding structured dismissals. The Supreme Court addressed structured dismissals in the first instance in Czyzewski v. Jevic Holding Corp. The Court held that a structured dismissal is a permissible means to resolve a Chapter 11 case so long as it does not violate the priority scheme set out in the Bankruptcy Code. Post-Jevic, courts have had to evaluate whether proposed structured dismissals violate the priority scheme in a way that they had not before. Moreover, courts have confronted suggestions to expand Jevic’s limitation on structured dismissals to bankruptcy sales and even beyond conflicts with the priority scheme. However, courts have been reluctant to expand Jevic beyond its core holding