Methane Fluxes Into Atmosphere from Fennoskandian Lakes

The experimental data on methane fluxes into the atmosphere from Fennoscandian lakes is analyzed. The contribution made by the lake network of this northern region to the atmospheric methane budget is estimated as 320 +/- 23 KtCH(4) per year. From 16 to 37% of the annual methane emission from Fennoscandian lakes is carried out by methane produced during the ice cover period. The methane fluxe rate from studied lakes is estimated as 2.6 +/- 0.2 gCH(4)m(-2) yr(-1). Among lakes of the region, small lakes (areaPeer reviewe

Stratifications and foliations in phase portraits of gene network models

Periodic processes of gene network functioning are described with good precision by periodic trajectories (limit cycles) of multidimensional systems of kinetic-type differential equations. In the literature, such systems are often called dynamical, they are composed according to schemes of positive and negative feedback between components of these networks. The variables in these equations describe concentrations of these components as functions of time. In the preparation of numerical experiments with such mathematical models, it is useful to start with studies of qualitative behavior of ensembles of trajectories of the corresponding dynamical systems, in particular, to estimate the highest likelihood domain of the initial data, to solve inverse problems of parameter identification, to list the equilibrium points and their characteristics, to localize cycles in the phase portraits, to construct stratification of the phase portraits to subdomains with different qualities of trajectory behavior, etc. Such an à priori geometric analysis of the dynamical systems is quite analogous to the basic section “Investigation of functions and plot of their graphs” of Calculus, where the methods of qualitative studies of shapes of curves determined by equations are exposed. In the present paper, we construct ensembles of trajectories in phase portraits of some dynamical systems. These ensembles are 2-dimensional surfaces invariant with respect to shifts along the trajectories. This is analogous to classical construction in analytic mechanics, i. e. the level surfaces of motion integrals (energy, kinetic moment, etc.). Such surfaces compose foliations in phase portraits of dynamical systems of Hamiltonian mechanics. In contrast with this classical mechanical case, the foliations considered in this paper have singularities: all their leaves have a non-empty intersection, they contain limit cycles on their boundaries. Description of the phase portraits of these systems at the level of their stratifications, and that of ensembles of trajectories allows one to construct more realistic gene network models on the basis of methods of statistical physics and the theory of stochastic differential equations

ВОЗМОЖНОСТИ ОПТИЧЕСКОЙ ДИФФУЗИОННОЙ СПЕКТРОСКОПИИ В ДИАГНОСТИКЕ РАКА МОЛОЧНОЙ ЖЕЛЕЗЫ (КЛИНИЧЕСКИЙ СЛУЧАЙ)

Breast cancer (BC) is one of the most common malignancies and the leading cause of cancer-related death in women worldwide. Currently, mammography and ultrasound are the methods most commonly used for the detection of BC, but these methods have significant limitations in the absence of “classic” visual symptoms of cancer in the breast tissue. In the complicated clinical situations, such methods as magnetic resonance imaging and positron emission tomography are used for the differential diagnosis of breast cancer. Over the past 20 years, the BC imaging capabilities have expanded due to the introduction of optical methods into clinical practice. These methods are based on differences in the optical properties between normal and pathological breast tissues. Optical imaging provides the ability to obtain indirect information about oxygenation, blood supply, delivery and consumption of oxygen in the breast tissue, as well as changes in its scattering properties. We present a clinical case of a woman with enlarged axillary lymph nodes. After the core biopsy of the lymph node, histological examination reveled breast cancer metastasis. The standard imaging modalities, such as digital mammography and ultrasound, did not show the evidence of breast cancer. However, the use of diffuse optical spectroscopy (DOS) allowed the detection of changes in the absorption and scattering coefficients in a small part of the breast tissue characteristic of a malignant tumor. Ultrasound and mammography images of this site of the breast demonstrated the features of benign lesion. After ultrasound-guided biopsy, cytological examination revealed cancer cells. Thus, the method of DOS allowed identification of changes characteristic to malignant tumor that was not detected by routine imaging modalities.Рак молочной железы (РМЖ) является одной из ведущих проблем клинической онкологии. Общепринятыми методами диагностики РМЖ являются рентгеновская маммография и ультразвуковое исследование, которые имеют существенные ограничения при отсутствии «классических» визуальных симптомов рака в ткани молочной железы. В сложных клинических ситуациях для дифференциальной диагностики РМЖ применяются такие методы, как МРТ и ПЭТ. В течение последних 20 лет возможности уточняющей диагностики РМЖ расширились благодаря внедрению в клиническую практику оптических методов, основанных на различиях оптических свойств нормальных и патологических тканей. Использование различных длин волн зондирующего излучения позволяет детектировать различные тканевые составляющие в зависимости от их спектра поглощения. Использование оптических методов позволяет получить косвенную информацию об оксигенации, кровенаполнении, доставке и потреблении кислорода в ткани молочной железы, а также об изменении ее рассеивающих свойств. В представленном клиническом случае метод оптической диффузионной спектроскопии (ОДС) позволил выявить существенные изменения оптических свойств образования молочной железы, не имеющего никаких «классических» визуальных симптомов рака. У пациентки заболевание проявилось увеличением аксиллярных лимфоузлов. После выполнения core-биопсии лимфатического узла при гистологическом исследовании был выявлен метастаз рака молочной железы. При этом в молочных железах по стандартным методам исследования (цифровая рентгеновская маммография, УЗИ) данных за наличие злокачественной опухоли не было. Однако методом ОДС в небольшом участке ткани молочной железы слева были выявлены изменения коэффициентов поглощения и рассеяния, характерные для злокачественной опухоли. По данным УЗИ и рентгеновской маммографии этот участок соответствовал доброкачественным изменениям. После пункции образования под ультразвуковым контролем цитологически были обнаружены раковые клетки. Таким образом, метод ОДС позволил выявить изменения, присущие злокачественной опухоли, в случае образования, не имеющего признаков малигнизации при использовании рутинных методов диагностики

Scientific rationale for replacing macrokinetic problem mikrokinetic level solutions for modeling of drying of disperse materials in a fluidized bed

It is shown that the drying process in a fluidized bed can be investigated at the level of individual particles, since the entire set of particles is equal to the hydro-and heat and mass transfer conditions

Vegetation and soils of tundra landscapes in the Pur-Taz interfluvial region

The landscape diversity of the tundra area in the Pur–Taz interfluvial region are analyzed using field and remote sensing data. For each land unit (microlandscape), botanical, microrelief, and soil descriptions are produced, projective covers of plant species are estimated, and seasonal soil thawing depths are defined. Additionally, the water table levels, pH, and electrical conductivity (EC) of peatland waters are measured in waterlogged microlandscapes