Ural State University

About: Ural State University is a based out in . It is known for research contribution in the topics: Magnetization & Magnetic field. The organization has 2816 authors who have published 3370 publications receiving 34825 citations.

The worldwide leaf economics spectrum

Abstract: Bringing together leaf trait data spanning 2,548 species and 175 sites we describe, for the first time at global scale, a universal spectrum of leaf economics consisting of key chemical, structural and physiological properties. The spectrum runs from quick to slow return on investments of nutrients and dry mass in leaves, and operates largely independently of growth form, plant functional type or biome. Categories along the spectrum would, in general, describe leaf economic variation at the global scale better than plant functional types, because functional types overlap substantially in their leaf traits. Overall, modulation of leaf traits and trait relationships by climate is surprisingly modest, although some striking and significant patterns can be seen. Reliable quantification of the leaf economics spectrum and its interaction with climate will prove valuable for modelling nutrient fluxes and vegetation boundaries under changing land-use and climate.

Synchronizing Automata and the Černý Conjecture

Abstract: We survey several results and open problems related to synchronizing automata. In particular, we discuss some recent advances towards a solution of the Cerný conjecture.

Models of class II methanol masers based on improved molecular data

Abstract: The class II masers of methanol are associated with the early stages of formation of high-mass stars. Modelling of these dense, dusty environments has demonstrated that pumping by infrared radiation can account for the observed masers. Collisions with other molecules in the ambient gas also play a significant role, but have not been well modelled in the past. Here we examine the effects on the maser models of newly available collision rate coefficients for methanol. The new collision data do not alter which transitions become masers in the models, but do influence their brightness and the conditions under which they switch on and off. At gas temperatures above 100 K the effects are broadly consistent with a reduction in the overall collision cross-section. This means, for example, that a slightly higher gas density than identified previously can account for most of the observed masers in W3(OH). We have also examined the effects of including more excited-state energy levels in the models, and find that these play a significant role only at dust temperatures above 300 K. An updated list of class II methanol maser candidates is presented.

Static conductivity of charged domain walls in uniaxial ferroelectric semiconductors

Abstract: By using Landau-Ginzburg-Devonshire theory, we numerically calculated the static conductivity of charged domain walls with different incline angles with respect to the spontaneous polarization vector in the uniaxial ferroelectric semiconductors of $n$ type. We used the effective mass approximation for the electron and hole density of states, which is valid at an arbitrary distance from the domain wall. Due to the electron accumulation, the static conductivity drastically increases at the inclined head-to-head wall by 1 order of magnitude for small incline angles \ensuremath{\theta} \ensuremath{\sim} \ensuremath{\pi}/40 and by 3 orders of magnitude for the perpendicular domain wall (\ensuremath{\theta} $=$ \ensuremath{\pi}/2). There are space-charge regions around the charged domain walls, but the quantitative characteristics of the regions (width and distribution of the carriers) appear very differently for the tail-to-tail and head-to-head walls in the considered donor-doped ferroelectric semiconductor. The head-to-head wall is surrounded by the space-charge layer with accumulated electrons and depleted donors with the same thickness (\ensuremath{\sim}40\ensuremath{-}100 correlation lengths). The tail-to-tail wall is surrounded by the thin space-charge layer with accumulated holes with thicknesses of \ensuremath{\sim}5--10 correlation lengths, a thick layer with accumulated donors with thicknesses of \ensuremath{\sim}100\ensuremath{-}200 correlation lengths, as well as the layer depleted by electrons with thicknesses of \ensuremath{\sim}100\ensuremath{-}200 correlation lengths. The conductivity across the tail-to-tail wall is at least an order of magnitude smaller than the one for the head-to-head wall due to the low mobility of the holes, which are improper carriers. The results are in qualitative agreement with recent experimental data for LiNbO${}_{3}$ doped with MgO.