Nonfrustrated magnetoelectric with incommensurate magnetic order in magnetic field

We discuss a model nonfrustrated magnetoelectric in which strong enough magnetoelectric coupling produces incommensurate magnetic order leading to ferroelectricity. Properties of the magnetoelectric in magnetic field directed perpendicular to wave vector describing the spin helix are considered in detail. Analysis of classical energy shows that in contrast to naive expectation the onset of ferroelectricity takes place at a field $H_{c1}$ that is lower than the saturation field $H_{c2}$. One has $H_{c1}=H_{c2}$ at strong enough magnetoelectric coupling. We show that at H=0 the ferroelectricity appears at $T=T_{FE}<T_N$. Qualitative discussion of phase diagram in $H-T$ plane is presented within mean field approach.Comment: 12 pages, 3 figures, accepted in JET

About assessment of training in competency-based education model

In article the questions of an assessment of results of training in education competence-based model are considered.В статье рассматриваются вопросы оценки результатов обучения в компетентностной модели образования

Modern education techniques: inverted training (experience)

В статье авторы рассматривают практический опыт применения метода перевернутого обучения. Показаны основные изменения в сфере высшего образования.In this article the experience of applying the method of inverted training is examined. The basic changes in the field of higher education are shown

Bose-Einstein condensation of magnons in magnets with predominant ferromagnetic interaction

We discuss Bose-Einstein condensation of magnons (BEC) in magnets with predominant ferromagnetic (FM) interaction in magnetic field $H$ near saturation ($H_c$). Because $H_c$ is independent of FM couplings, magnetic materials of this type can have small $H_c$ that makes them promising candidates for experimental investigation of BEC. Ferromagnets with easy-plane anisotropy and antiferromagnets (AFs) containing weakly coupled FM planes or chains are discussed in detail. We observe small effective interaction between magnons near the QCP in such magnets, in contrast to AFs with strong AF coupling previously discussed. In particular, this smallness allows us to find crossovers in the critical temperature $T_c(H)\propto (H_c-H)^{1/\phi}$ from $\phi=3/2$ to $\phi=1$ in quasi-1D magnets, and from $\phi=3/2$ to $\phi\approx1$ ($T_c\ln T_c\propto H_c-H$) in quasi-2D ones.Comment: 9 pages, 4 figure. The paper has been rewritten considerably. In particular, discussion of crossovers in the critical temperature in quasi-low-dimensional magnets is adde

Female reproductive tract microbiome and early miscarriages

The review presents new data on the impact of the vaginal and uterine microbiome on the local immunity, including defense against sexually transmitted infections, and its association with other factors of miscarriage

Late pleistocene sedimentation history of the Shirshov Ridge, Bering Sea

The analysis of the lithology, grain-size distribution, clay minerals, and geochemistry of Upper Pleistocene sediments from the submarine Shirshov Ridge (Bering Sea) showed that the main source area was the Yukon–Tanana terrane of Central Alaska. The sedimentary materials were transported by the Yukon River through Beringia up to the shelf break, where they were entrained by a strong northwestward-flowing sea current. The lithological data revealed several pulses of ice-rafted debris deposition, roughly synchronous with Heinrich events, and periods of weaker bottom-current intensity. Based on the geochemical results, we distinguished intervals of an increase in paleoproductivity and extension of the oxygen minimum zone. The results suggest that there were three stages of deposition driven by glacioeustatic sea-level fluctuations and glacial cycles in Alaska