Large temperature dependence of the Casimir force at the metal-insulator transition

The dependence of the Casimir force on material properties is important for both future applications and to gain further insight on its fundamental aspects. Here we derive a general theory of the Casimir force for low-conducting compounds, or poor metals. For distances in the micrometer range, a large variety of such materials is described by universal equations containing a few parameters: the effective plasma frequency, dissipation rate of the free carriers, and electric permittivity in the infrared range. This theory can also describe inhomogeneous composite materials containing small regions with different conductivity. The Casimir force for mechanical systems involving samples made with compounds that have a metal-insulator transition shows an abrupt large temperature dependence of the Casimir force within the transition region, where metallic and dielectric phases coexist.Comment: 23 pages, 9 figure

Synthesis of phosphorylated piperazines

Heating 3-methyl-1,2-butadienyl phosphonates with piperazine leads to the formation of 2-piperazinyl-butenyl phosphonates containing the enamine functionality. From the reaction of piperazine with four equivalents of 1,2-butadienyl phosphonate a bis(phosphonate) is obtained, in which the piperazine bridge links two phosphorylbutene fragments. © 2013 Copyright Taylor and Francis Group, LLC

Stable topological textures in a classical 2D Heisenberg model

We show that stable localized topological soliton textures (skyrmions) with $\pi_2$ topological charge $\nu \geq 1$ exist in a classical 2D Heisenberg model of a ferromagnet with uniaxial anisotropy. For this model the soliton exist only if the number of bound magnons exceeds some threshold value $N_{\rm cr}$ depending on $\nu$ and the effective anisotropy constant $K_{\rm eff}$. We define soliton phase diagram as the dependence of threshold energies and bound magnons number on anisotropy constant. The phase boundary lines are monotonous for both $\nu=1$ and $\nu >2$, while the solitons with $\nu=2$ reveal peculiar nonmonotonous behavior, determining the transition regime from low to high topological charges. In particular, the soliton energy per topological charge (topological energy density) achieves a minimum neither for $\nu=1$ nor high charges, but rather for intermediate values $\nu=2$ or $\nu=3$.Comment: 8 pages, 4 figure

HISTORY AND MODERN MODEL Of NEPHROLOGY SERVICE IN MULTIPROfILE HOSPITAL

The purpose of the study was to present the stages of effective nephrological service forming and to evaluate the output results of the Regional Nephrological Center (RNC) as the unit of multidisciplinary hospital. Results and discussion. The nephrology service of State Novosibirsk Regional Clinical Hospital began to form in 1978 with the opening of nephrology hemodialysis and kidney transplantation departments. The RNC was established in 1993 on the base of a territorial register for patients with chronic renal failure. Currently, the RNC includes the department of nephrology, the register for patients with chronic kidney disease (CKD) of 3–5 stages, nephrological counseling office, offices for potential recipients of renal transplantation and for patients with transplanted kidney, the office of permanent outpatient peritoneal dialysis. As a result, the prevalence and structure of CKD 3–5 stages in the Novosibirsk region are comparable to those in Europe, the availability of the renal replacement therapy, including the number of patients with a functioning renal transplant exceeds the nationwide indicators. Conclusion. The model of the nephrological service of a multidisciplinary hospital provides accounting and dispensation of patients with CKD, increases the effectiveness of treatment, including methods of renal replacement therapy

К вопросу о придании статуса резервной валюты юаню

The presented article opens an essence of internationalization of currency, defines, what factors are necessary in order that the Yuan became the international currency, pays the main attention to international payments which are carried out by means of Yuan, in particular, analyzes prospects of the investments expressed in Yuan.Представленная статья раскрывает суть понятия «интернационализация» валюты, определяет какие факторы необходимы для того, чтобы юань стал международной валютой, уделяет основное внимание международным расчетам, которые проводятся с помощью юаня, в частности, анализирует перспективы инвестиций, выраженных в юане

Chirality tunneling in mesoscopic antiferromagnetic domain walls

We consider a domain wall in the mesoscopic quasi-one-dimensional sample (wire or stripe) of weakly anisotropic two-sublattice antiferromagnet, and estimate the probability of tunneling between two domain wall states with different chirality. Topological effects forbid tunneling for the systems with half-integer spin S of magnetic atoms which consist of odd number of chains N. External magnetic field yields an additional contribution to the Berry phase, resulting in the appearance of two different tunnel splittings in any experimental setup involving a mixture of odd and even N, and in oscillating field dependence of the tunneling rate with the period proportional to 1/N.Comment: 4 pages + 2 figures, references correcte

Validation of the SCID-hu Thy/Liv mouse model with four classes of licensed antiretrovirals.

BackgroundThe SCID-hu Thy/Liv mouse model of HIV-1 infection is a useful platform for the preclinical evaluation of antiviral efficacy in vivo. We performed this study to validate the model with representatives of all four classes of licensed antiretrovirals.Methodology/principal findingsEndpoint analyses for quantification of Thy/Liv implant viral load included ELISA for cell-associated p24, branched DNA assay for HIV-1 RNA, and detection of infected thymocytes by intracellular staining for Gag-p24. Antiviral protection from HIV-1-mediated thymocyte depletion was assessed by multicolor flow cytometric analysis of thymocyte subpopulations based on surface expression of CD3, CD4, and CD8. These mice can be productively infected with molecular clones of HIV-1 (e.g., the X4 clone NL4-3) as well as with primary R5 and R5X4 isolates. To determine whether results in this model are concordant with those found in humans, we performed direct comparisons of two drugs in the same class, each of which has known potency and dosing levels in humans. Here we show that second-generation antiretrovirals were, as expected, more potent than their first-generation predecessors: emtricitabine was more potent than lamivudine, efavirenz was more potent than nevirapine, and atazanavir was more potent than indinavir. After interspecies pharmacodynamic scaling, the dose ranges found to inhibit viral replication in the SCID-hu Thy/Liv mouse were similar to those used in humans. Moreover, HIV-1 replication in these mice was genetically stable; treatment of the mice with lamivudine did not result in the M184V substitution in reverse transcriptase, and the multidrug-resistant NY index case HIV-1 retained its drug-resistance substitutions.ConclusionGiven the fidelity of such comparisons, we conclude that this highly reproducible mouse model is likely to predict clinical antiviral efficacy in humans

Эхолокация рукокрылых (Chiroptera Blumenbach, 1779) как элемент их экологической пластичности

Aim. The aim of this work was to briefly summarize the current understanding of the phenomenon of echolocation in the order of bats (Chiroptera Blumenbach, 1779). Discussion. The paper discusses: The place of bats among other taxonomic groups of animals that have the ability of echolocation; the history of the discovery of "ear vision" in bats by L. Spallanzani in the 18th century; the first scientifically based assumptions regarding the use of ultrasound by bats and the discovery of this phenomenon in the middle of the last century; methods for emitting and receiving ultrasound by various taxonomic groups of bats; physical patterns underlying the propagation of ultrasonic waves; characteristics of the returned echo and algorithms for echolocation in bats; echolocation interactions between insectivorous bats and nocturnal moths and possibilities for ultrasonic monitoring of bat populations. Conclusion. The inclusion of ultrasound monitoring of bat populations in integrated ecological and virological studies could form a new point of growth in systems to ensure biological security at both national and global levels. © 2020 Kamerton. All rights reserved