Ball Milled Gd Flakes Subjected to Heat Treatments: Structure, Magnetic and Magnetocaloric Properties

Gd flake samples were prepared by conventional ball milling technique starting from rapidly quenched Gd ribbons and followed by vacuum annealing in different conditions. Heat treatments were conducted in a vacuum at selected temperatures up to 600 K. The structural features, magnetic and magnetocaloric properties were comparatively analyzed. The change in magnetic entropy was calculated using an experimental set of magnetic isotherms measured in a wide range of temperatures. The variations in the refrigeration capacity and the exponent of the magnetic entropy change in the external magnetic field were carefully calculated and analyzed.The research funding from the Ministry of Science and Higher Education of the Russian Federation (Ural Federal University Program of Development within the Priority-2030 Program) is gratefully acknowledged. This research was supported in part by the Universidad del País Vasco/Euskal Herriko Unibertsitatea UPV/EHU Research Groups Funding

Propagation and interaction of ultrashort electromagnetic pulses in nonlinear media with a quadratic-cubic nonlinearity

Propagation of extremely short unipolar pulses of electromagnetic field ("videopulses") is considered in the framework of a model in which the material medium is represented by anharmonic oscillators (approximating bound electrons) with quadratic and cubic nonlinearities. Two families of exact analytical solutions (with positive or negative polarity) are found for the moving solitary pulses. Direct simulations demonstrate that the pulses are very robust against perturbations. Two unipolar pulses collide nearly elastically, while collisions between pulses with opposite polarities and a small relative velocity are inelastic, leading to emission of radiation and generation of a small-amplitude additional pulse.Comment: 12 pages, 10 figure

Genome analysis of American minks reveals link of mutations in Ras-related protein-38 gene to Moyle brown coat phenotype

Over 35 fur colours have been described in American mink (Neovison vison), only six of which have been previously linked to specific genes. Moyle fur colour belongs to a wide group of brownish colours that are highly similar to each other, which complicates selection and breeding procedures. We performed whole genome sequencing for two American minks with Moyle (m/m) and Violet (a/a m/m /p/p) phenotypes. We identified two frame-shift mutations in the gene encoding Ras-related protein-38 (RAB38), which regulates the trafficking of tyrosinase-containing vesicles to maturing melanosomes. The results highlight the role of RAB38 in the biogenesis of melanosomes and melanin and the genetic mechanism contributing to hair colour variety and intensity. These data are also useful for tracking economically valuable fur traits in mink breeding programmes

An easy and safe method of subconjunctival injection of antimetabolites in glaucoma surgery

Aim: The use of 5-fluorouracil in glaucoma surgery is associated with a high risk of corneal complications, as even minimal doses of the drug at the ocular surface inhibit corneal epithelial cell division and lead to corneal epitheliopathy and erosion. The aim of this study was to evaluate the clinical and functional results of the proposed method of postoperative adjuvant subconjunctival injection of 5-fluorouracil after non-penetrating deep sclerectomy (NPDS) in comparison with the control group. Methods: Patients with primary open-angle glaucoma who underwent NPDS and received at least 1 subconjunctival injection of 5-fluorouracil in the postoperative period were included in a two-group retrospective comparative study. Patients who received a subconjunctival injection of 5-fluorouracil after surgery using the standard technique were included in Group 1; Group 2 included patients who received an injection using the proposed method. Best-corrected visual acuity (BCVA), intraocular pressure (IOP), rate of corneal complications, and number of office visits during the first 4 weeks after surgery were analysed. Results: The compared groups did not differ in demographic characteristics, preoperative BCVA, and IOP parameters. Fluorescein-stained corneal epithelial defects were statistically significantly more frequent in Group 1 compared to Group 2, P < 0.001. Four weeks post NPDS IOP reduction was greater in Group 2, P = 0.042. Mean BCVA loss was 1.9 lines in Group 1 and 1.3 lines in Group 2, P < 0.001. The number of follow-up visits during the first month after surgery was lower in Group 2 than in Group 1, P = 0.002. Conclusions: The proposed method was simple and effective in reducing the risk of corneal epithelial defects after subconjunctival injection of 5-fluorouracil, significantly improving clinical and functional outcomes of NPDS and reducing the need for outpatient visits

Genetic and neuronal regulation of sleep by neuropeptide VF

Sleep is an essential and phylogenetically conserved behavioral state, but it remains unclear to what extent genes identified in invertebrates also regulate vertebrate sleep. RFamide-related neuropeptides have been shown to promote invertebrate sleep, and here we report that the vertebrate hypothalamic RFamide neuropeptide VF (NPVF) regulates sleep in the zebrafish, a diurnal vertebrate. We found that NPVF signaling and npvf-expressing neurons are both necessary and sufficient to promote sleep, that mature peptides derived from the NPVF preproprotein promote sleep in a synergistic manner, and that stimulation of npvf-expressing neurons induces neuronal activity levels consistent with normal sleep. These results identify NPVF signaling and npvf-expressing neurons as a novel vertebrate sleep-promoting system and suggest that RFamide neuropeptides participate in an ancient and central aspect of sleep control

Obituary: Professor Alexander Kessenikh (1932-2021)

On September 15, 2021, professor Alexander V. Kessenikh died. He was known for his works on nuclear magnetic resonance (NMR) and history of science

Quantum Phase Transition in Frustrated Two-Dimensional Antiferromagnets

We study frustrated, two-dimensional, quantum antiferromagnets in the vicinity of a quantum transition from a non-collinear, magnetically-ordered ground state to a quantum disordered phase. The general scaling properties of this transition are described. A detailed study of a particular field-theoretic model of the transition, with bosonic spin-1/2 spinon fields, is presented. Explicit universal scaling forms for a variety of observables are obtained and the results are compared with numerical data on the spin-1/2 triangular antiferromagnet. Universal properties of an alternative field-theory, with confined spinons, are also briefly noted.Comment: 51 pages, REVTEX 3.0, 5 uuencoded EPS figures appended, YCTP-xxz

Search for pseudoscalar bosons decaying into e+e− pairs in the NA64 experiment at the CERN SPS

We report the results of a search for a light pseudoscalar particle a that couples to electrons and decays to e+e− performed using the high-energy CERN SPS H4 electron beam. If such light pseudoscalar exists, it could explain the ATOMKI anomaly (an excess of e+e− pairs in the nuclear transitions of 8Be and 4He nuclei at the invariant mass ≃17  MeV observed by the experiment at the 5 MV Van de Graaff accelerator at ATOMKI, Hungary). We used the NA64 data collected in the “visible mode” configuration with a total statistics corresponding to 8.4×1010 electrons on target (EOT) in 2017 and 2018. In order to increase sensitivity to small coupling parameter ε we also used the data collected in 2016-2018 in the “invisible mode” configuration of NA64 with a total statistics corresponding to 2.84×1011 EOT. The background and efficiency estimates for these two configurations were retained from our previous analyses searching for light vector bosons and axionlike particles (ALP) (the latter were assumed to couple predominantly to γ). In this work we recalculate the signal yields, which are different due to different cross section and lifetime of a pseudoscalar particle a, and perform a new statistical analysis. As a result, the region of the two dimensional parameter space ma−ε in the mass range from 1 to 17.1 MeV is excluded. At the mass of the central value of the ATOMKI anomaly (the first result obtained on the beryllium nucleus, 16.7 MeV) the values of ε in the range 2.1×10−4<ε<3.2×10−4 are excluded

Nonlinearity and disorder: Classification and stability of nonlinear impurity modes

We study the effects produced by competition of two physical mechanisms of energy localization in inhomogeneous nonlinear systems. As an example, we analyze spatially localized modes supported by a nonlinear impurity in the generalized nonlinear Schr\"odinger equation and describe three types of nonlinear impurity modes --- one- and two-hump symmetric localized modes and asymmetric localized modes --- for both focusing and defocusing nonlinearity and two different (attractive or repulsive) types of impurity. We obtain an analytical stability criterion for the nonlinear localized modes and consider the case of a power-law nonlinearity in detail. We discuss several scenarios of the instability-induced dynamics of the nonlinear impurity modes, including the mode decay or switching to a new stable state, and collapse at the impurity site.Comment: 18 pages, 22 figure