A Renormalization Group For Treating 2D Coupled Arrays of Continuum 1D Systems

We study the spectrum of two dimensional coupled arrays of continuum one-dimensional systems by wedding a density matrix renormalization group procedure to a renormalization group improved truncated spectrum approach. To illustrate the approach we study the spectrum of large arrays of coupled quantum Ising chains. We demonstrate explicitly that the method can treat the various regimes of chains, in particular the three dimensional Ising ordering transition the chains undergo as a function of interchain coupling.Comment: 5 pages, 4 figure

A Numerical Renormalization Group for Continuum One-Dimensional Systems

We present a renormalization group (RG) procedure which works naturally on a wide class of interacting one-dimension models based on perturbed (possibly strongly) continuum conformal and integrable models. This procedure integrates Kenneth Wilson's numerical renormalization group with Al. B. Zamolodchikov's truncated conformal spectrum approach. Key to the method is that such theories provide a set of completely understood eigenstates for which matrix elements can be exactly computed. In this procedure the RG flow of physical observables can be studied both numerically and analytically. To demonstrate the approach, we study the spectrum of a pair of coupled quantum Ising chains and correlation functions in a single quantum Ising chain in the presence of a magnetic field.Comment: 4 pages, 4 figure

Human Capital Investments Among Veterinarians

Professional labor markets can be affected by alternating periods of excess or scarcity in labor. The phenomenon is most prevalent in labor markets where a substantial lag occurs between occupational choice and labor market entry. In this paper, a unique longitudinal dataset from veterinary labor markets is used to identify factors significantly associated with volatility in labor supply. Our econometric analysis establishes a statistically significant relationship between boom-bust cycles in labor and certain pertinent variables: entry-level earnings, a demand proxy, and supply-side features. Results support the notion that decision-makers gauge the expected levels of these variables when making career choices

Statistics of Heat Transfer in Mesoscopic Circuits

A method to calculate the statistics of energy exchange between quantum systems is presented. The generating function of this statistics is expressed through a Keldysh path integral. The method is first applied to the problem of heat dissipation from a biased mesoscopic conductor into the adjacent reservoirs. We then consider energy dissipation in an electrical circuit around a mesoscopic conductor. We derive the conditions under which measurements of the fluctuations of heat dissipation can be used to investigate higher order cumulants of the charge counting statistics of a mesoscopic conductor.Comment: 9 pages, 6 figure

Continuous Neel to Bloch Transition as Thickness Increases: Statics and Dynamics

We analyze the properties of Neel and Bloch domain walls as a function of film thickness h, for systems where, in addition to exchange, the dipole-dipole interaction must be included. The Neel to Bloch phase transition is found to be a second order transition at hc, mediated by a single unstable mode that corresponds to oscillatory motion of the domain wall center. A uniform out-of-plane rf-field couples strongly to this critical mode only in the Neel phase. An analytical Landau theory shows that the critical mode frequency varies as the square root of (hc - h) just below the transition, as found numerically.Comment: 4 pages, 4 figure

Analytical and micromagnetic study of a Neel domain wall

Journals published by the American Physical Society can be found at http://journals.aps.org/For ferromagnets with exchange, dipolar interaction, and uniaxial anisotropy, by both analytic methods and micromagnetic simulations we study Neel domain walls in thin ferromagnetic strips of finite width. Comparison of the numerical results with the analytics yields parameter values that had been unspecified by the analytics, and determines the modifications needed to describe the magnetization both near the strip center and near the boundaries. With no uniaxial anisotropy, the domain wall center can be described by the same hyperbolic secant form as with uniaxial anisotropy, but the effective anisotropy constant must now be thought of as increasing with increasing film thickness and decreasing with increasing film width

Interaction effects on magnetooscillations in a two-dimensional electron gas

Motivated by recent experiments, we study the interaction corrections to the damping of magnetooscillations in a two-dimensional electron gas (2DEG). We identify leading contributions to the interaction-induced damping which are induced by corrections to the effective mass and quantum scattering time. The damping factor is calculated for Coulomb and short-range interaction in the whole range of temperatures, from the ballistic to the diffusive regime. It is shown that the dominant effect is that of the renormalization of the effective electron mass due to the interplay of the interaction and impurity scattering. The results are relevant to the analysis of experiments on magnetooscillations (in particular, for extracting the value of the effective mass) and are expected to be useful for understanding the physics of a high-mobility 2DEG near the apparent metal-insulator transition.Comment: 24 pages; subsection adde

Comment on "Critique of the foundations of time-dependent density functional theory" [Phys. Rev.A. 75, 022513 (2007)]

A recent paper (Phys. Rev A. 75, 022513 (2007), arXiv:cond-mat/0602020) challenges exact time-dependent density functional theory (TDDFT) on several grounds. We explain why these criticisms are either irrelevant or incorrect, and that TDDFT is both formally exact and predictive.Comment: 4 pages; This is a Comment on the paper cited above, also at arXiv:cond-mat/060202

Homologous Seminal Plasma and Glutathione Promote Pre-capacitation Motility and Structural Stability of Cryopreserved Ram Spermatozoa

Reduced glutathione (GSH) and homologous ram seminal plasma (HSP), used as additives in cryopreserving (CP) media prior to freezing, showed conflicting results in retaining structural integrity and progressive motility in post-thawed ram spermatozoa. The aims of this research were (1) to assess the effect of GSH and/or HSP supplementation via soybean-lecithin CP extender on cryopreserved ram spermatozoa viability, morphology and motility pattern; and (2) to assess the effect of incubation in the context of the previous aim. Quantitatively and qualitatively, homogenized and pooled ram ejaculates (N=10) were extended with one of the following extenders Control (C)-tris-based, GSH and HSP-free, experimental-1 (E1)-C + GSH 5 mM, experimental-2 (E2)-C + HSP 20 % and experimental-3 (E3)-GSH 5 mM + HSP 20 %. Following thawing, samples were taken at 0-A nd 3-hours from each group (n=10) and were assessed for spermatozoa viability, morphology, and motility pattern. C-0h samples yielded a spermatozoa population with low viability, altered head morphology and highly deviated motility pattern. E3-3h samples yielded spermatozoa with unaffected viability, head morphology and high progressive motility. In conclusion, E3 extender added to cryopreserved-thawed ram spermatozoa is most efficient in obtaining high viability, unaltered head morphology, and progressive motility