Ballistic magnon heat conduction and possible Poiseuille flow in the helimagnetic insulator Cu2_2OSeO3_3

We report on the observation of magnon thermal conductivity $\kappa_m\sim$ 70 W/mK near 5 K in the helimagnetic insulator Cu$_2$OSeO$_3$, exceeding that measured in any other ferromagnet by almost two orders of magnitude. Ballistic, boundary-limited transport for both magnons and phonons is established below 1 K, and Poiseuille flow of magnons is proposed to explain a magnon mean-free path substantially exceeding the specimen width for the least defective specimens in the range 2 K $<T<$ 10 K. These observations establish Cu$_2$OSeO$_3$ as a model system for studying long-wavelength magnon dynamics.Comment: 10pp, 9 figures, accepted PRB (Editor's Suggestion

Contemplation as a Special Psychological Phenomenon and a Form of Self-Therapy

Созерцание представляется важной составной частью ментальных процессов, состояний, а также свойств личности, не совпадая полностью ни с одним из базисных психических процессов. Особенностью процесса созерцания является его фактическое осознание индивидом как особого состояния, при том что не вполне осознается содержание созерцания и его трехчастная структура (предсозерцание, собственно созерцание и постсозерцание). Функциональной особенностью созерцания является внутренняя, скрытая переработка либо коррекция или трансформация микро-, мезо- и макросмыслов жизнедеятельности человека. Немаловажно также то, что этот процесс переосмысления, согласно полученным данным, весьма эмоционально позитивен для индивида. Процесс созерцания можно квалифицировать так же, как спонтанную психологическую самотерапию личности.Contemplation seems to be an important component of mental processes, states, and personality traits, not completely coinciding with any of the basic mental processes. A feature of the process of contemplation is its actual awareness by the individual as a special state, despite the fact that the content of contemplation and its tripartite structure (pre-contemplation, contemplation proper and post-contemplation) are not fully realized. A functional feature of contemplation is the internal, hidden processing, or correction or transformation of micro-, meso- and macro-meanings of human life. It is also important that this process of rethinking, according to the data obtained, is very emotionally positive for the individual. The process of contemplation can also be qualified as a spontaneous psychological self-therapy of the individual

Magnetic-field dependence of low-energy magnons, anisotropic heat conduction, and spontaneous relaxation of magnetic domains in the cubic helimagnet ZnCr2Se4

Anisotropic low-temperature properties of the cubic spinel helimagnet ZnCr2Se4 in the single-domain spin-spiral state are investigated by a combination of neutron scattering, thermal conductivity, ultrasound velocity, and dilatometry measurements. In an applied magnetic field, neutron spectroscopy shows a complex and nonmonotonic evolution of the spin-wave spectrum across the quantum-critical point that separates the spin-spiral phase from the field-polarized ferromagnetic phase at high fields. A tiny spin gap of the pseudo-Goldstone magnon mode, observed at wave vectors that are structurally equivalent but orthogonal to the propagation vector of the spin helix, vanishes at this quantum critical point, restoring the cubic symmetry in the magnetic subsystem. The anisotropy imposed by the spin helix has only a minor influence on the lattice structure and sound velocity but has a much stronger effect on the heat conductivities measured parallel and perpendicular to the magnetic propagation vector. The thermal transport is anisotropic at T < 2 K, highly sensitive to an external magnetic field, and likely results directly from magnonic heat conduction. We also report long-time thermal relaxation phenomena, revealed by capacitive dilatometry, which are due to magnetic domain motion related to the destruction of the single-domain magnetic state, initially stabilized in the sample by the application and removal of magnetic field. Our results can be generalized to a broad class of helimagnetic materials in which a discrete lattice symmetry is spontaneously broken by the magnetic order.Comment: 13 pages, 8 figures + Supplemental Materia

ИЗМЕНЕНИЕ ФАУНЫ НЕКОТОРЫХ БИОГЕЛЬМИНТОВ РЫБ ОЗЕРА СЕВАН И ИХ ПРОМЕЖУТОЧНЫХ ХОЗЯЕВ В УСЛОВИЯХ ГИДРОЭКОЛОГИЧЕСКИХ ПРЕОБРАЗОВАНИЙ

The infeсtion of biohelminths of fishes in Sevan Lake is studied. 9 types of biohelminths are revealed: in a body cavity, intestines, heart and crystalline lenses of eyes. The analysis of changes of specific composition of the helminths in dynamics, taking into account changes of fauna of their intermediate hosts, in conditions of hydroecological transformations of the lake is conducted.Изучена зараженность рыб озера Севан гельминтами. Выявлено 9 видов биогельминтов: в полости тела, кишечнике, сердце и хрусталиках глаз. Проведен анализ изменений видового состава обнаруженных гельминтов в динамике, с учетом изменений фауны их промежуточных хозяев, в условиях гидроэкологических преобразований озера

Chemomagnetism, magnetoconcentration effect and "fishtail" anomaly in chemically-induced granular superconductors

Within a 2D model of Josephson junction arrays (created by 2D network of twin boundary dislocations with strain fields acting as insulating barrier between hole-rich domains in underdoped crystals), a few novel effects expected to occur in intrinsically granular material are predicted including: (i) Josephson chemomagnetism (chemically induced magnetic moment in zero applied magnetic field) and its influence on a low-field magnetization (chemically induced paramagnetic Meissner effect), and (ii) magnetoconcentration effect (creation of oxygen vacancies in applied magnetic field) and its influence on a high-field magnetization (chemically induced analog of "fishtail" anomaly). The conditions under which these effects can be experimentally measured in non-stoichiometric high-T_c superconductors are discussed.Comment: 5 LaTeX pages (jetpl.sty included), 3 EPS figures. To be published in JETP Letters (January 2003

Association of the AGT, ACE, NOS3 polymorphism with subclinical arterial wall changes and cardiovascular diseases risk factors

Background. Renin-Angiotensin-Aldosterone System activation (RAAS) and nitric oxide (NO) reduction lead to the changes in the arterial wall, which, in turn, create a favourable environment for the development of cardiovascular diseases (CVD). There is only limited knowledge of the influence of proteins participating in the RAAS activation and providing NO bioavailability on the parameters of the arterial wall state (pulse wave velocity (PWV), carotid artery intima-media thickness (cIMT), endothelium-dependent vasodilation (EDVD), presence of atherosclerotic plaques) and risk factors of CVD. Aim. Finding the association between the AGT, ACE, NOS3 polymorphism and PWV, cIMT, EDV, presence of atherosclerotic plaques and risk factors of CVD in healthy subjects. Methods. Using intergroup analysis and models of multiple logistic regression, we examined the association of AGT с.521СТ polymorphism, AСE InsDel polymorphism, NOS3 с.894GT polymorphism with arterial wall changes and risk factors of CVD in 160 healthy people of different ages. Results. The CT genotype of AGT с.521СТ polymorphism was associated with lower levels of systolic blood pressure (BP) (p=0.013) and central systolic BP (p=0.029), higher level of Insulin-Like Growth Factor (IGF) (p=0.027). The DD genotype of ACE InsDel polymorphism was associated with a higher waist/hip ratio (p=0.044), lower level of high density lipoprotein cholesterol (p=0.01), lower index of EDVD (p=0.042), higher incidence ofendothelial dysfunction (ED) (p=0.026). The GG genotype of NOS3 с.894GT polymorphism was associated with higher levels of central systolic BP (p=0.022) and central mean BP (p=0.033), total cholesterol (p=0.025), low density lipoprotein cholesterol (p=0.014) and IGF (p=0.042), higher incidence of ED (p=0.007), albuminuria (p=0.032) and insulin resistance (p=0.03). Conclusion. We have found the association of the AСE and NOS3 polymorphism with endothelial dysfunction and the metabolic status

Voltage Responses to Optical Pulses of Unbiased Normal and Superconducting Samples

The direct transformation of the energy of an incident high-energy photon into a measurable potential difference within an absorbing metal is investigated. Experimental evidence is presented that the effect arises from the inherent energy dependence of the electronic density of states, rather than from a simple temperature excursion. The similarities between the results on Al and YBa2Cu3O7 samples indicate that the effect is universal in nature. We assert it may be used as the basis of a fast, energy resolving, individual photon detector for the ultraviolet radiation and x-rays

Safety Study of an Original Mesenchymal Stromal Cell Secretome-Based Medicinal Product for Spermatogenesis Restoration

Currently, there are no effective and safe medicinal products for idiopathic male infertility. Previous studies in two animal models of infertility (short-term cryptorchidism in rats and doxorubicin-induced testicular injury in mice) have shown the effectiveness of an originator medicinal product based on the mesenchymal stromal cell (MSC) secretome.The aim of the study was to evaluate the toxicity profile of the MSC secretome-based medicinal product in rats after local intratesticular or intramuscular administration.Materials and methods. The MSC secretome is a combination of factors secreted by MSCs in low-glucose Dulbecco’s modified Eagle’s medium (DMEM-LG) for MSC conditioning. In the single-dose toxicity study, the MSC secretome-based medicinal product was injected under the testicular tunica albuginea of male Wistar rats (15 per group) at doses of 15 and 25 relative units (RU) per animal, which are 1.5 and 2.5 times higher than the therapeutic dose (10 RU). In the repeat-dose toxicity study, male Wistar rats (10 per group) received intramuscular thigh injections of the medicinal product on days 1, 6, and 12 at doses of 15 and 25 RU per animal. The local tolerance study involved histopathological examination of the testes and thighs at the injection site. All studies included control groups of intact animals and animals similarly injected with blank DMEM-LG. The early follow-up period was 14 days, and the late follow-up period was 42 days.Results. The rats showed no changes in the general condition after single and repeated doses of the MSC secretome-based medicinal product. Single subtunical doses induced moderate irritation; its signs included pathological changes in individual seminiferous tubules: epithelial atrophy (70% of the animals on day 14; 55% at late follow-up) and sperm stasis (70% of the animals). Similar changes were observed in the blank DMEM-LG group (up to 80% of the animals). There were no pathological changes in the tissues after repeated injections. A transient increase in alkaline phosphatase activity was detected in animals after their third intramuscular injection at a dose of 25 RU; the other biochemical parameters were normal in all study groups.Conclusions. The MSC secretome-based medicinal product has a favourable safety profile following both intratesticular and intramuscular administration, as it does not cause any permanent changes in the studied organs and tissues

The regulatory role of cystatin C in autophagy and neurodegeneration

Autophagy is a dynamic cellular process involved in the turnover of proteins, protein complexes, and organelles through lysosomal degradation. It is particularly important in neurons, which do not have a proliferative option for cellular repair. Autophagy has been shown to be suppressed in the striatum of a transgenic mouse model of Parkinson’s disease. Cystatin C is one of the potent regulators of autophagy. Changes in the expression and secretion of cystatin C in the brain have been shown in amyotrophic lateral sclerosis, Alzheimer’s and Parkinson’s diseases, and in some animal models of neurodegeneration, thus proving a protective function of cystatin C. It has been suggested that cystatin C plays the primary role in amyloidogenesis and shows promise as a therapeutic agent for neurodegenerative diseases (Alzheimer’s and Parkinson’s diseases). Cystatin C colocalizes with the amyloid β-protein in the brain during Alzheimer’s disease. Controlled expression of a cystatin C peptide has been proposed as a new approach to therapy for Alzheimer’s disease. In Parkinson’s disease, serum cystatin C levels can predict disease severity and cognitive dysfunction, although the exact involvement of cystatin C remains unclear. The aim: to study the role of cystatin C in neurodegeneration and evaluate the results in relation to the mechanism of autophagy. In our study on humans, a higher concentration of cystatin C was noted in cerebrospinal fluid than in serum; much lower concentrations were observed in other biological fluids (intraocular fluid, bile, and sweat). In elderly persons (61–80 years old compared to practically healthy people at 40–60 years of age), we revealed increased cystatin C levels both in serum and intraocular fluid. In an experiment on C57Bl/6J mice, cystatin C concentration was significantly higher in brain tissue than in the liver and spleen: an indication of an important function of this cysteine protease inhibitor in the brain. Using a transgenic mouse model of Parkinson’s disease (5 months old), we demonstrated a significant increase in osmotic susceptibility of brain lysosomes, depending on autophagy, while in a murine model of Alzheimer’s disease, this parameter did not differ from that in the appropriate control