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Over the course of two years, the contribution of fungi and bacteria to the process of net ammonification in soddy-pale podzolic soil under a wood-sorrel birch forest (Yaroslavl oblast, Russia) was determined, using inhibitory analysis. The mycobiota of saprotrophic fungi was dominated by representatives of Penicillium Link (46–99%) and Trichoderma Pers. (3–40%) genera. It was found that temperature and soil moisture can regulate seasonal changes in the total number of fungi and yeasts in the soil of a birch forest, and the relationships between seasonal changes in the contents of Corg and Norg in soil and the total numbers of fungi and yeasts were of an alternating nature. Inhibitory analysis showed a close contribution of fungi and bacteria to the mineralization of nitrogen compounds in soil of the birch forest, with a slight predominance of fungi in the first year of the study and a slight dominance of bacteria in the second year. Inhibitors increased ammonification activity in all soil horizons under a birch forest compared to the control. Microbial biomass nitrogen accounted for 0.8 to 3.9% of total soil nitrogen. [ABSTRACT FROM AUTHOR]

For two years, the contribution of fungi and bacteria to the process of net ammonification in soddy-podzolic soil of the sorrel–blueberry birch forest of Yaroslavl oblast was determined using inhibitory analysis. It was established that the litter is characterized by equal participation of fungi and bacteria in this process. In the humus horizon, a slight excess of fungi over bacteria was noted in years of normal moisture and there was a clear dominance of fungi in dry years. In the eluvial part of the profile, the close contribution of these groups was noted, with an insignificant prevalence of one of them over the years of study. The maximum air temperature is able to change the seasonal dynamics of the abundance of saprotrophic fungi in the soil and to some extent form the generic structure of the mycobiota in the horizons of the soil profile of the birch forest. [ABSTRACT FROM AUTHOR]

Denitrification losses of nitrogen-containing gases in the biome of boreal forests are discussed. In the soils of coniferous and deciduous forests of Western Europe, 0.57 ± 0.2 and 1.0 ± 0.2 kg N–N2O/ha/year are lost during denitrification. In North America this figure was 0.35 ± 0.29 kg N–N2O/ha/yr for all stands. The emission of N2O from forest soils correlated with the input of nitrogen from the atmosphere with r = 0.47 in coniferous forests and with r = 0.68 in deciduous plantations, returning to the atmosphere up to 30% of the nitrogen supplied with atmospheric precipitation. With a high input of nitrogen from the atmosphere, the emission of nitrogen-containing gases reached 20 kg N/ha/yr. Of these, NO, N2O, and N2 accounted for 21, 15, and 64%. Measurements of NO and especially N2 emissions remain very rare, leading to incomplete estimates of denitrification losses. Denitrification remains the most complex process in the nitrogen cycle, with no definitive methods for measuring it. [ABSTRACT FROM AUTHOR]

The study aims to assess the role of social support, sociocultural adjustment, and other social and demographic factors in international students' mental health. In total, 193 international first-year students studying Health and Technology Sciences in Lithuania filled out a self-report questionnaire. The study revealed that overall 59% of international students had symptoms of depression and 36%—of anxiety. Students' well-being was sufficient in 56% of the cases. The regression analyses were conducted to test the role of sociocultural adjustment, social support, English reading skills, and the study field for mental health and well-being. The multivariate regression model revealed that sociocultural adjustment is a stronger predictor compared to social support for depressiveness (βs = 0.42), anxiety (βs = 0.30), psychosomatic symptoms (βs = − 0.24), and subjective health (βs = 0.16), though social support was a stronger independent predictor for well-being (βs = 0.37). Moreover, sociocultural adjustment and social support were stronger predictors than gender, while English reading skills and study field were non-significant indicators. [ABSTRACT FROM AUTHOR]

The study aims to assess the role of social support, sociocultural adjustment, and other social and demographic factors in international students' mental health. In total, 193 international first-year students studying Health and Technology Sciences in Lithuania filled out a self-report questionnaire. The study revealed that overall 59% of international students had symptoms of depression and 36%—of anxiety. Students' well-being was sufficient in 56% of the cases. The regression analyses were conducted to test the role of sociocultural adjustment, social support, English reading skills, and the study field for mental health and well-being. The multivariate regression model revealed that sociocultural adjustment is a stronger predictor compared to social support for depressiveness (βs = 0.42), anxiety (βs = 0.30), psychosomatic symptoms (βs = − 0.24), and subjective health (βs = 0.16), though social support was a stronger independent predictor for well-being (βs = 0.37). Moreover, sociocultural adjustment and social support were stronger predictors than gender, while English reading skills and study field were non-significant indicators. [ABSTRACT FROM AUTHOR]

Abstract—The functioning of mycorrhizal associations in forest ecosystems is discussed. Mycorrhizae are involved in supplying plants with nutrients and improve their growth, but they can also inhibit plant development. The level of participation of ecto-ericoid mycorrhizae in the carbon cycle of boreal forests is considered to be very significant. According to isotope indications, the role of mycorrhizae in the nitrogen cycle is high in the tundra and less pronounced in boreal forests. Mycorrhizae are involved in the decomposition of soil OM to obtain available nitrogen, but the enzymatic mechanisms of this process and the pathways for the movement of N and P from fungal cells to plants are largely unknown. Mycorrhizae prevent nitrogen losses from forest soils during leaching. Mycorrhizal networks contribute to the processes of reforestation and structuring of plantations and protect against pathogens and pests. [ABSTRACT FROM AUTHOR]

We consider the projection method with a fractional smoothness stabilizer for approximating the problem of reconstructing the wavefront based on its slopes. The stability of the method is demonstrated on the scale of periodic functions of two arguments. Conditions for matching the stabilizer parameters with the grid step are found; this permits one to derive estimates of the convergence rate of the projection method that are consistent with the smoothness of the slopes. Using interpolation theory, we obtain estimates for the accuracy of the method under natural requirements for the smoothness of slopes from the scale of anisotropic Sobolev spaces of fractional smoothness. [ABSTRACT FROM AUTHOR]

The results of a two-year study conducted to assess the outcomes of a long-term forest isolation experiment are presented. A section of a spruce–birch forest in Yaroslavl oblast (6S4B, 100 years old, quality class I) was isolated from the presence of moose for 25 years. It is established that net mineralization of nitrogen compounds in the 0- to 12-cm soil horizon measured from May to October under field conditions was more intense in the unfenced area in comparison with the isolated area (15 ± 0.4 and 10.4 ± 0.5 g N/m2, respectively). Carbon dioxide emissions from the soil in that same time period were lower in the unfenced area (319 ± 47 g C/m2) than in the isolated area (552 ± 82 g C/m2). On the isolated site, 19 mg of nitrogen is mineralized in the soil per gram of С-СО2; while on the control site, it is 47 mg of nitrogen per gram of С‑СО2. In the isolated variant, the distribution of ammonium concentrations in the upper (0–4 cm) soil horizon is normal, while in the control variant, it is lognormal due to the presence of elk. [ABSTRACT FROM AUTHOR]

We study spiral waves in a mathematical model of a nonlinear optical system with a feedback loop. Starting from a delayed scalar diffusion equation in a thin annulus with oblique derivative boundary conditions, we shrink the annulus and derive the limiting equation on a circle. Based on the explicitly constructed normal form of the Hopf bifurcation for the one-dimensional delayed scalar diffusion equation, we make predictions about the existence and stability of two-dimensional spirals that we verify in direct numerical simulations, observing pulsating and rotating spiral waves. [ABSTRACT FROM AUTHOR]

We consider a new formulation of the Fourier-filtering problem that uses matrix Fourier-filters as the controls in nonlinear optical models described by quasi-linear functional-differential diffusion equations. Solvability of the control problem is proved for various classes of matrix Fourier-filters with a time-integral objective functional. Differentiability of the functional with respect to the matrix Fourier-filter and convergence of a variant of the gradient projection method are proved. Examples of numerical simulation of controlled structure formation are presented, and the advantages of matrix Fourier-filters compared with traditional multiplier filters are demonstrated. [ABSTRACT FROM AUTHOR]

We consider a model of nonlinear interaction of femtosecond pulses with a Kerr nonlinear medium, allowing for first and second order dispersion, nonlinear response dispersion, and mixed time and space derivatives. The invariants are constructed by a transformation of the generalized nonlinear Schrodinger equation that involves changing to new functions and reduces the original equation to a form without the nonlinear response derivatives and the mixed derivatives. Appropriate conservation laws are established for the transformed equation. The invariants derived in this article lead to conservative difference schemes and allow control of computer simulation results. [ABSTRACT FROM AUTHOR]

Wavefront reconstruction from local slope estimates is performed by a family of variational methods with a fractional order stabilizer designed to ensure best uniform reconstruction of the front on the entire frequency spectrum. Analytical and numerical investigation of the space-frequency characteristic of the family and numerical experiments with reconstruction of regular and turbulent wavefronts have demonstrated the advantage of the proposed method over the common Simpson method. [ABSTRACT FROM AUTHOR]

An iterative algorithm is described for three-dimensional deconvolution in the Fourier plane using parallel computations on CPU and GPU. The algorithm demonstrates easy scalability and can process any number of input images of any size. It is only limited by the local storage volume. [ABSTRACT FROM AUTHOR]

The purpose of the paper is to theoretically investigate 2D wave patterns in a nonlinear optical system with diffractive feedback. We consider a delayed functional differential diffusion equation on a thin annulus with Neumann boundary conditions. To study pattern formation phenomena, we construct the Faria normal form of a Hopf bifurcation, which is necessarily degenerate because the equation exhibits O(2) symmetry. The coefficients of the normal form determine the excitation of rotating or standing waves with the prescribed spatio-temporal characteristics, but these coefficients can be expressed only implicitly. However, for sufficiently thin annuli, the equation corresponds to a limit 1D model on a circle, which was carefully analysed in our previous papers and whose normal form was explicitly calculated. 2D wave stability predictions that we make based on the normal form of the limit 1D model are in good agreement with direct numerical simulations of the 2D model. To accelerate computation, we elaborated an efficient fast finite Hankel transform algorithm for thin annular domains. [ABSTRACT FROM AUTHOR]

A novel statement of the Fourier filtering problem based on the use of matrix Fourier filters instead of conventional multiplier filters is considered. The basic properties of the matrix Fourier filtering for the filters in the Hilbert-Schmidt class are established. It is proved that the solutions with a finite energy to the periodic initial boundary value problem for the quasi-linear functional differential diffusion equation with the matrix Fourier filtering Lipschitz continuously depend on the filter. The problem of optimal matrix Fourier filtering is formulated, and its solvability for various classes of matrix Fourier filters is proved. It is proved that the objective functional is differentiable with respect to the matrix Fourier filter, and the convergence of a version of the gradient projection method is also proved. [ABSTRACT FROM AUTHOR]

In this paper we construct an O(2)-equivariant Hopf bifurcation normal form for a model of a nonlinear optical system with delay and diffraction in the feedback loop whose dynamics is governed by a system of coupled quasilinear diffusion equation and linear Schrödinger equation. The coefficients of the normal form are expressed explicitly in terms of the parameters of the model. This makes it possible to constructively analyze the phase portrait of the normal form and, based on the analysis, study the stability properties of the bifurcating rotating and standing waves. [ABSTRACT FROM AUTHOR]

Surfactants with two and three monosaccharide-based heads and a perfluoroalkyl tail have been synthesized. Perfluoroalkyl C 3 -symmetric triol and C 2 -symmetric diol were conveniently prepared via Cu-catalyzed azide–alkyne cycloaddition between a fluorous alkyne and tertiary and secondary azides, respectively. Glycosylation of the perfluoroalkyl diol and triol led to orthoester-type structures, which were evaluated for their capacity to stabilize aqueous emulsions of highly fluorinated anesthetics. The self-assembly properties of the tri-sugar amphiphile were examined by transmission electron microscopy. [ABSTRACT FROM AUTHOR]

Net mineralization of nitrogen was measured in the horizons of peaty podzolic gley soil (At1, 0-6 cm, At2, 6-10 cm, and A2, 10-20 cm) of the bilberry-sphagnum birch forest from May to the beginning of November in 2011 and 2012; it comprised 2.1 ± 0.4, 2.7 ± 0.4, 1.2 ± 0.4, and 1.9 ± 0.2, 1.9 ± 0.2, 0.8 ± 0.15 g N/m, respectively. The total of 6 ± 0.7 and 4.6 ± 0.3 g N/m were mineralized in the soil profile in the years 2011 and 2012, respectively, with the contribution of ammonification being more than 99%. The seasonal variations in nitrogen mineralization correlated with the temperature and soil moisture content in At1 and At2 horizons. The efficiency of nitrogen mineralization in soil horizons under the birch forest was expressed by similar values, namely, 0.005 ± 0.0008, 0.0064 ± 0.0008, and 0.003 ± 0.001 mg N/g C per day, and this suggests a high efficiency of substrate utilization in the eluvial part of the soil profile. The seasonal variation of carbon dioxide production correlated with the ammonification in the At1 horizon with r = 0.85 and p = 0.03 in 2011 and 2012, and in the At2 horizon with r = 0.65 and p = 0.16 in 2012. Over the studied period, production of ammonia depended on soil moistening in the dry year of 2011 ( r = 0.91; p = 0.01) and soil temperature in the wet year of 2012 ( r = 0.78; p = 0.06). The productivity of the process equaled 3 ± 0.9 mg N/m, or 30 g N/ha in both years of observation. [ABSTRACT FROM AUTHOR]

The parabolic functional differential equation $\frac{{\partial u}} {{\partial t}} = D\frac{{\partial ^2 u}} {{\partial x^2 }} - u + K(1 + \gamma \cos u(x + \theta ,t - T)) $ is considered on the circle [0, 2π]. Here, D > 0, T > 0, K > 0, and γ ∈ (0, 1). Such equations arise in the modeling of nonlinear optical systems with a time delay T > 0 and a spatial argument rotated by an angle θ ∈ [0, 2π) in the nonlocal feedback loop in the approximation of a thin circular layer. The goal of this study is to describe spatially inhomogeneous rotating-wave solutions bifurcating from a homogeneous stationary solution in the case of a Andronov-Hopf bifurcation. The existence of such waves is proved by passing to a moving coordinate system, which makes it possible to reduce the problem to the construction of a nontrivial solution to a periodic boundary value problem for a stationary delay differential equation. The existence of rotating waves in an annulus resulting from a Andronov-Hopf bifurcation is proved, and the leading coefficients in the expansion of the solution in powers of a small parameter are obtained. The conditions for the stability of waves are derived by constructing a normal form for the Andronov-Hopf bifurcation for the functional differential equation under study. [ABSTRACT FROM AUTHOR]

The total mineralization of nitrogen in the AO-A1 (0-6 cm), A1 (6-11 cm), and A2 (11-21 cm) horizons of a soddy pale-podzolic soil under an oxalis birch forest in Yaroslavl oblast was measured from May to November in 2009 and 2010 and comprised 6.7 ± 0.9, 3.0 ± 0.4, and 5.5 ± 0.6 g of N/m in 2009 and 5.6 ± 0.5, 2.5 ± 0.2, and 2.1 ± 0.5 g of N/m in 2010, respectively. The total nitrification reached 0.4 ± 0.1, 1.1 ± 0.2, and 1.4 ±0.1 g of N/m in 2009 and 1.0, 0.6, and 0.7 g of N/m in 2010. Overall, the amount of mineralized nitrogen in the 21-cm-deep soil layer in 2009 and 2010 constituted 15.2 ± 1.1 and 10.2 ± 0.7 g of N/m, respectively. The contribution of nitrification to the nitrogen mineralization amounted to 20%. The seasonal variations in the soil temperature and moistening affected the concentrations of ammonium in the upper horizons and the accumulation of ammonium in the AO-A1 and A1 horizons. The combined effect of the temperature and moisture controlled the ammonification in the AO-A1 horizon ( R = 0.83 at p = 0.16 in 2010), the nitrification in all the studied horizons ( R = 0.86 at p= 0.13 in 2009), and the ammonia emission from the soil surface ( R = 0.92 at p = 0.06 in 2010). A correlation between the seasonal dynamics of the ammonification and the CO emission was found for the AO-A1 horizon ( r = 0.64 at p = 0.16 in 2010) and was absent in the deeper layers of the soil profile. The nitrogen losses from the soil surface due to the ammonia emission in the investigated periods reached 95 ± 31 g of N/ha (2009) and 33 ± 30 g of N/ha (2010). [ABSTRACT FROM AUTHOR]

A projection-difference method is developed for approximating controlled Fourier filtering for quasilinear parabolic functional-differential equations. The method relies on a projection-difference scheme (PDS) for the approximation of the differential problem and derives a O(τ + h) bound on the rate of convergence of PDS in the weighted energy norm without prior assumptions of additional smoothness of the generalized solutions. The PDS leads to a natural approximation of the objective functional in the optimal Fourier filtering problem. A bound of the same order is obtained for the rate of convergence in the functional of the problems approximating the Fourier filter control problem. [ABSTRACT FROM AUTHOR]

novel technique is proposed for analyzing the convergence of a projection difference scheme as applied to the initial value problem for a quasilinear parabolic operator-differential equation with initial data u ∈ H. The technique is based on the smoothing property of solutions to the differential problem for t > 0. Under certain conditions on the nonlinear term, a new estimate of order $O(\sqrt \tau + h)$ for the convergence rate in a weighted energy norm is obtained without using a priori assumptions on the additional smoothness of weak solutions. [ABSTRACT FROM AUTHOR]

Imaging of enzyme activity in living subjects promises many applications in both basic and translational researches from helping elucidate the enzyme function and mechanism in biology to better disease detection and monitoring, but the complexity and dynamics of enzymatic reactions in living systems present unique challenges for probe design. This critical reviewexamines the approaches in recent literature to in vivoimaging of the activity of a variety of enzyme targets with an emphasis on the chemical perspective of probe design, structure and function. Strategies for designing enzyme-activated probes based on a variety of molecular scaffolds including small molecules, organic and inorganic nanoparticles, and genetically encoded proteins for commonly used molecular imaging modalities—whole body optical (fluorescence, bioluminescence) imaging, magnetic resonance imaging, and radionuclide-based tomographic imaging, are critically evaluated. Recent advances in combining multiple modalities to imaging enzyme activity in living subjects are also highlighted (255 references). [ABSTRACT FROM AUTHOR]

The article coments on the analytical and numerical methods of control transformation problem in the space arguments, and differential equations. The paper suggests the control problem statement of a two-dimensional transformation for the spatial arguments and the analysis of its properties like uniform quasidifferentiability of the objective function, its gradient HÖlder condition, the gradient projection method convergence, and the control problem solvability on a compact set.

An interaction of laser pulse, containing a few cycles, with substance is a modern problem, attracting attention of many researches. The frequency conversion is a key problem for a generation of such pulses in various ranges of frequencies. Adequate description of such pulse interaction with a medium is based on a slowly evolving wave approximation (SEWA), which has been proposed earlier for a description of propagation of the laser pulse, containing a few cycles, in a medium with cubic nonlinear response. Despite widely applicability of the frequency conversion for various nonlinear optics problems solutions, SEWA has not been applied and developed for a theoretical investigation of the frequency doubling process until present time. In this study the set of generalized nonlinear Schrödinger equations describing a second harmonic generation of the super-short femtosecond pulse is derived. The equations set contains terms, describing the pulses self-steepening, and the second order dispersion (SOD) of the pulse, a diffraction of the beam as well as mixed derivatives. We propose the transform of the equations set to a type, which does not contain both the mixed derivatives and time derivatives of the nonlinear terms. This transform allows us to derive the integrals of motion of the problem: energy, spectral invariants and Hamiltonian. We show the existence of two specific frequencies (singularities in the Fourier space) inherent to the problem. They may cause an appearance of non-physical absolute instability of the problem solution if the spectral invariants are not taken into account. Moreover, we claim that the energy preservation at the laser pulses propagation may not occur if these invariants do not preserve. Developed conservation laws, in particular, have to be used for developing of the conservative finite-difference schemes, preserving the conservation laws difference analogues, and for developing of adequate theory of the modulation instability of the laser pulses, containing a few cycles. [ABSTRACT FROM AUTHOR]

A modified bispectral method is proposed for solving the inverse problem of image reconstruction in ophthalmology. Modeling shows that the method produces stable results for typical symmetric aberrations of the human eye's imaging system in the presence of turbulent distortions leading to a signalternating optical transfer function. [ABSTRACT FROM AUTHOR]

Abstract: The paper is devoted to development of the laser ektacytometry technique for evaluation of the statistical characteristics of inhomogeneous ensembles of red blood cells (RBCs). We have analyzed theoretically laser beam scattering by the inhomogeneous ensembles of elliptical discs, modeling red blood cells in the ektacytometer. The analysis shows that the laser ektacytometry technique allows for quantitative evaluation of such population characteristics of RBCs as the cells mean shape, the cells deformability variance and asymmetry of the cells distribution in the deformability. Moreover, we show that the deformability distribution itself can be retrieved by solving a specific Fredholm integral equation of the first kind. At this stage we do not take into account the scatter in the RBC sizes. [Copyright &y& Elsevier]

A Tikhonov-regularized bispectral variational method is proposed for image restoration in the presence of strong phase distortions. This method combines a number of advantages of the bispectral approach, such as preservation and restoration of phase information, invariance to random shifts of the original signal, and no requirement of high-accuracy prior information about statistical properties of observed signals. In combination with the Tikhonov-regularized variational method, which is adapted to stable processing of large images, we obtain a fairly efficient image restoration method. Test results in the presence of atmospheric and underwater phase distortions reported in this article establish the advantages of the proposed method relative to the traditional recursive bispectral method. [ABSTRACT FROM AUTHOR]

A comparative analysis of the most promising photovoltaic systems for the measurement of linear and angular quantities is presented. It is shown that by means of such a comparison it becomes possible to optimize a measurement system with respect to individual elements and converters as well as with respect to circuit designs so as to increase the performance and precision characteristics. [ABSTRACT FROM AUTHOR]

We give a comparative analysis of the most competitive photoelectric systems for measuring linear and angular quantities. As the basic parameters for the comparison, we select the most important characteristics of such systems: the possibility for automating them, improving response speed, accuracy, and reliability. [ABSTRACT FROM AUTHOR]

The article reports on the significance of WhozThat protocol to computer users in the U.S. The mobile social networking revolution is prevalent, thus paving the way in enriching local social interaction among users. Online social networks is important because it provide a wealth of personal contextual information including name, picture, contact information, gender, relationship status/interests and friendship information concerning user interconnection. WhozThat is motivated by the idea that the rich contextual information from online social networks into the real world of local human interactions, thus enriching local social interaction. Such protocol is advantageous due to its simplicity, energy/bandwidth efficiency, agnosticism and extensibility.

Abstract  The range of measuring instruments developed at the N. . Bauman Moscow State Technical University is considered. All of the measuring heads of these instruments are built according the same fundamental scheme with the use of periodic measures in the form of raster, diffraction grating, and interference structures. These heads may be used in multicoordinate and multiposition instruments for measuring linear and angular quantities, and they are also built into contemporary optical-mechanical devices for their modernization. [ABSTRACT FROM AUTHOR]

Abstract  Questions related to efforts aimed at decreasing the position error of the moving parts of measuring transducers when measuring displacements are considered. It is remarked that scanning by the indicator element of the measurement coupling is most effective in photoelectric transducers, since it makes it possible to optimize the measuring circuit of the system and mode of operation of the system’s transducers. [ABSTRACT FROM AUTHOR]