Winter Adaptations in the Willow Ptarmigan

The willow ptarmigan, Lagopus lagopus, dwells in a vast area with a variety of climatic and biotic conditions. Populations from northeast Asia must cope with extremely low temperatures along with progressive depletion of food resources throughout the winter. Being unable to roost in the snow at -40 degrees C, a ptarmigan's daily life would cost 3.2-3.5 basal metabolic rate (BM), but by burrowing in snow for up to 21 hours per day, the bird saves at least 1.0 BM. To meet daily energy demands on a midwinter day a ptarmigan needs about 60 g of food (dry weight), consisting mostly of willow buds and twigs. Early in winter the diet contains 12-15% protein and 20-25% fiber, declining later to 7-8% protein and increasing up to 35% fiber. Nitrogen concentration, crucial for food digestibility, declines by half (from 0.35 to 0.18%) during the six winter months. Nitrogen also causes increased food consumption in a feedback pattern. Nevertheless, many birds lose body weight constantly. To recover losses they need a more nutritious diet after the snow starts to melt. Thus, the willow ptarmigan's adaptation to the polar winter appears as an individual balancing act within a few specific limits. Higher density of conspecific birds, colder winters and/or later springs may cause physiological damage to individuals, which eventually would lower the reproduction rate within the breeding population.Key words: willow ptarmigan, winter ecology, metabolic rates, food quality, fiber digestionMots clés: lagopède des saules, écologie hivernale, taux de métabolisme, qualité alimentaire, digestion des fibre

Laparoscopic Repair of a Posttraumatic Left-Sided Diaphragmatic Hernia Complicated by Strangulation and Colon Obstruction

Posttraumatic diaphragmatic hernia complicated with colonic obstruction can be managed by experienced surgeons with minimally invasive methods

Closed Abrikosov Vortices in a Superconducting Cylinder

The new type of solutions of the London equation for type-II superconductors is obtained to describe the ring-shaped (toroidal) Abrikosov vortices. The specific feature of these solutions is the self-consistent localization of both the supercurrent and the magnetic field, enabling one to construct compact magnetic structures inside a superconductor. The torus vortex contraction caused by the vortex instability leads to the destruction of the Cooper pairing and the formation of a normal electron stream in the vicinity of the torus axis. The thermodynamic condition for the excitation of a small closed vortex by a bunch of charged particles contains the fine-structure constant as a determining parameter.Comment: LaTex using revtex, 12 pages. 5 Figures available upon request from [email protected] Accepted for publication in Physica

Rate of equilibration of a one-dimensional Wigner crystal

We consider a system of one-dimensional spinless particles interacting via long-range repulsion. In the limit of strong interactions the system is a Wigner crystal, with excitations analogous to phonons in solids. In a harmonic crystal the phonons do not interact, and the system never reaches thermal equilibrium. We account for the anharmonism of the Wigner crystal and find the rate at which it approaches equilibrium. The full equilibration of the system requires umklapp scattering of phonons, resulting in exponential suppression of the equilibration rate at low temperatures.Comment: Prepared for the proceedings of the International School and Workshop on Electronic Crystals, ECRYS-201

Геологічні умови комплексування і сепарації рідкіснометалевого, рідкісноземельного та благородного зруденіння в Приазовському блоці Українського щита

Найбільш перспективні корінні комплексні рідкіснометалеві, рідкісноземельні родовища і рудопрояви Приазовського геоблоку УЩ мають унікальну комплексність зруденіння: Zr-Hf, Nb, ta, TR, Y, Ce, La, Th та інші – вони пов’язані з проникненням перегрітих мантійних плюмів (діапірів) в проміжок часу 1,9-1,6 млрд. років тому. Родовища золота (Au-Ag, Cu, Zn, Pb, W, Mo-Re, Bi, Te) локалізовані в тектонічних зонах геоблоку. The most promising indigenous complex rare-metal, rare earth deposits and ore Priazovsky geoblock Ukrainian shield have the unique complexity of the mineralization: Zr-Hf, Nb, Ta, TR, Y, Ce, La, Th and others - they are linked to the penetration of superheated mantle plumes (diapirs) in the interval time 1,9-1,6 billion years ago. Deposits of gold (Au-Ag, Cu, Zn, Pb, W, Mo-Re, Bi, Te) localized in the tectonic zones geoblock

Thermopower of a single electron transistor in the regime of strong inelastic cotunneling

We study Coulomb blockade oscillations of thermoelectric coefficients of a single electron transistor based on a quantum dot strongly coupled to one of the leads by a quantum point contact. At temperatures below the charging energy E_C the transport of electrons is dominated by strong inelastic cotunneling. In this regime we find analytic expressions for the thermopower as a function of temperature T and the reflection amplitude $r$ in the contact. In the case when the electron spins are polarized by a strong external magnetic field, the thermopower shows sinusoidal oscillations as a function of the gate voltage with the amplitude of the order of $e^{-1}|r|\frac{T}{E_C}$. We obtain qualitatively different results in the absence of the magnetic field. At temperatures between $E_C$ and $E_C|r|^2$ the thermopower oscillations are sinusoidal with the amplitude of order $e^{-1}|r|^2 \ln \frac{E_C}{T}$. On the other hand, at $T\ll E_C|r|^2$ we find non-sinusoidal oscillations of the thermopower with the amplitude $\sim e^{-1} |r| \sqrt{T/E_C} \ln(E_C/T)$.Comment: 14 pages, 3 figure

Role of interference in MM-wave driven DC transport in two dimensional electron gas

In this paper we point out that in addition to the density of states effect proposed in Ref.\cite{durst,anderson} one should consider the effect of constructive interference between the multi-MM-wave-photon processes shown in Fig.2. This process enhances the dark value of the conductivity. When the sample is very pure, i.e., when the transport life time is very long, this interference effect quickly diminishes as the MM-wave frequency deviates from the cyclotron frequency. In this paper we also present the linear response theory in the presence of strong harmonic time-dependent perturbation

Quasideterminant solutions of a non-Abelian Toda lattice and kink solutions of a matrix sine-Gordon equation

Two families of solutions of a generalized non-Abelian Toda lattice are considered. These solutions are expressed in terms of quasideterminants, constructed by means of Darboux and binary Darboux transformations. As an example of the application of these solutions, we consider the 2-periodic reduction to a matrix sine-Gordon equation. In particular, we investigate the interaction properties of polarized kink solutions.Comment: 14 pages; 4 picture