169 research outputs found

    Method of control of efficiency of investment projects based on real option theory and method of analysis of hierarchies

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    The article is devoted to the development of a method for valuation and control of the efficiency of investment projects under conditions of high uncertainty. The limitations of the traditional valuation methods of the efficiency of investment projects are highlighted and a more relevant approach through the application of real option theory is proposed that allows for evaluating a project based on tis multivariance and the possibility of decision making at every stage of its development. The article shows that, despite the high relevance of the real options theory, its practical use is very difficult for a number of reasons. The main problem of estimating the value of real options is the need to use in the calculation a sufficient number of a priori statistics regarding the project, which is unfeasible. The authors propose a method in which the probabilistic characteristics of the model project are replaced with correct expert ratings. The method is referred to as the modified ROV-method (MROV). This method is based on the binomial model of assessing the value of real options by building a decision tree. At each node of the tree the project might develop in line with an “optimistic” or “pessimistic” forecast. Since the development of the project under any scenario depends on a number of criteria of the environment, the task of assessing the value of real options becomes a multicriteria one. One of the most sound and practically relevant methods of solving such problems is the method of analytic hierarchy process, which is the basis of the developed MROV method. The article also details the algorithm of implementing this method to determine quantitative estimates of the relative probabilities of the development of the project on “optimistic” or “pessimistic” scenarios in each node of the binomial tree. The resulting estimates subsequently used as weights in the calculation of the net present value of the optional investment project for a decision on the feasibility of its implementation and inclusion of the real options being evaluated in the project.Статья посвящена разработке метода оценки и управления эффективностью инвестиционных проектов в условиях высокой степени неопределенности. Обозначена ограниченность традиционных методов оценки эффективности инвестиционных проектов и предложен более актуальный подход на основе применения теории реальных опционов, который позволяет оценить проект с учетом его многовариантности и возможности принятия решений на каждом этапе его развития. В статье показано, что, несмотря на высокую актуальность теории реальных опционов, ее практическое использование весьма затруднительно по ряду причин. Основной проблемой в отношении оценки стоимости реальных опционов является необходимость использования в расчетах достаточного количества априорных статистических данных относительно проекта, что на практике является труднореализуемой задачей. Авторами предложен метод, в рамках которого вероятностные характеристики модели проекта заменяются корректными экспертными оценками, названный модифицированным ROV-методом (MROV). За основу данного метода взята биномиальная модель оценки стоимости реального опциона, основанная на построении дерева решений, в каждом узле которого возможно развитие проекта по оптимистическому или пессимистическому прогнозу. Поскольку развитие проекта по какому-либо сценарию зависит от ряда критериев среды, то задача оценки стоимости реального опциона становится многокритериальной задачей. Одним из наиболее обоснованных и практически адекватных методов решения подобных задач является метод анализа иерархий, который и положен в основу разрабатываемого MROV-метода. Также в статье подробно описан алгоритм реализации данного метода для определения количественных оценок относительных вероятностей развития проекта по «оптимистическому» или «пессимистическому» сценарию в каждом узле биномиального дерева решений. Полученные оценки в последующем используются в качестве весов при расчете чистой приведенной стоимости вариативного опционального инвестиционного проекта для принятия решения о целесообразности его реализации и включении в проект, оцениваемых реальных опционов

    Features of Morphometric Changes in Platelets and Red Blood Cells in Women with Various Forms of Hypertensive Disorders in the Third Trimester of Pregnancy

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    Background. Arterial hypertension during pregnancy is accompanied by pronounced changes in microcirculation and hemostasis in the system, the state of which is largely determined by the structural and functional properties of red blood cells and platelets. The study of quantitative and morphometric characteristics of blood cells will expand the existing understanding of their role in the pathogenesis of hypertensive disorders.Aim of the research. To study the quantitative and morphometric indicators of red blood cells and platelets in pregnant women with various forms of hypertensive disorders, on the basis of which to develop an additional method for the diagnosis of preeclampsia. Materials and methods. 237 women in the third trimester of pregnancy were examined. The main group (167 women) included patients with various forms of hypertensive disorders. The comparison group included 70 pregnant women without signs of hypertensive disorders. The characteristic of clinical and anamnestic data of the studied groups is given. A comparative analysis of the number and morphometric parameters of red blood cells and platelets was performed.Results. With moderate and severe preeclampsia, a decrease in the level of red blood cells, hemoglobin and hematocrit was not accompanied by changes in red blood cell indices. In women with preeclampsia, regardless of the presence of chronic arterial hypertension, an increase in the average dry weight, average volume and degree of platelet anisocytosis was detected. In severe preeclampsia and preeclampsia with underlying of  chronic arterial hypertension, an increase in the number of large forms of platelets and their granulocytosis was revealed, and in addition, in severe cases of preeclampsia, a decrease in platelet level was noted.Conclusions. Modern hematological analyzers make it possible to establish the nature of not only quantitative, but also morphometric changes in red blood cells and platelets, thereby complementing the existing understanding of the pathogenetic mechanisms underlying hypertensive disorders in pregnancy. Using average dry platelet mass and average blood pressure may be useful in diagnosing preeclampsia

    Возможности использования амплитудно-угловых характеристик поверхностных и подповерхностных волн для контроля материалов с поверхностно упрочнённым неоднородным слоем

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    Improving the efficiency of ultrasonic control of hardened surface layers of metal products with a heterogeneous structure obtained using different technologies is a pressing problem of industrial production. The purpose of this work was to investigate the possibilities of measuring the depth of the surface inhomogeneous layer of steel objects on the basis of the use of amplitude and amplitude-angle characteristics of surface and subsurface transverse waves.The analysis of ultrasonic methods of control of physical and mechanical properties of metals by using surface and subsurface waves and experimentally investigated amplitude-angular characteristics of surface waves, the maximum angle of which increases by 3° at change of dimensionless layer depth hλ from zero to0.82. For the first time, the ratio of normalized amplitudes of surface waves taken at certain angles on theamplitude-angle characteristic curve obtained in the echo mode was proposed to be used as correlating parameters with the depth of the hardened layer. As a result of this research, the possibility of using a phased array transducers to solve the above problems.The effect of the hardened layer depth varying from zero to five in the working frequency range of 1.8– 10 MHz on the peculiarities of the refraction effect (including interference) and dependence of the subsurface wave amplitude on the acoustic base has been studied, making it possible to establish conditions that provide for the determination of the hardened layer depth.Circuit solutions have been offered in order to increase the efficiency of control of properties of the surface layers of metal articles on the basis of utilization of small-aperture transducers and ultrasonic reflectors making it possible to form fields of surface waves of different directional pattern. Повышение эффективности ультразвукового контроля упрочненных поверхностных слоев металлоизделий с неоднородной структурой, полученных по различным технологиям, является актуальной проблемой опытно-промышленного производства. Целью данной работы являлось исследование возможностей измерения глубины поверхностного неоднородного слоя стальных объектов на основе использования амплитудных и амплитудно-угловых характеристик поверхностных и подповерхностных поперечных волн.Проведён анализ ультразвуковых методов контроля физико-механических свойств металлов с использованием поверхностных и подповерхностных волн и экспериментально исследованы амплитудно-угловые характеристики поверхностных волн, максимальный угол которых увеличивается на 3°при изменении безразмерной глубины слоя hλ от нуля до 0,82. Впервые предложено использовать в качестве коррелирующих параметров с глубиной упрочнённого слоя отношение нормированных амплитуд поверхностных волн, взятых под определёнными углами на кривой амплитудно-угловой характеристики, полученной в эхо-режиме. В результате проведённых исследований была выявлена возможностьиспользования преобразователей с фазированной решёткой для решения вышеуказанных задач.Исследовано влияние глубины упрочнённого слоя, изменяющейся от нуля до пяти в рабочем диапазоне частот 1,8–10 МГц, на особенности эффекта преломления (в том числе интерференции) и импенданса амплитуды подповерхностной волны на акустической базе, что позволило установить условия, обеспечивающие определение глубины упрочнённого слоя.Предложены схемные решения для повышения эффективности контроля свойств поверхностных слоев металлических изделий на основе использования малоапертурных преобразователей и ультразвуковых отражателей, позволяющих формировать поля поверхностных волн различной направленности

    Possibilities of Using of Surface and Subsurface Waves’ Amplitude-Angle Characteristics for Control of Materials with Surface-Hardened Inhomogeneous Layer

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    Improving the efficiency of ultrasonic control of hardened surface layers of metal products with a heterogeneous structure obtained using different technologies is a pressing problem of industrial production. The purpose of this work was to investigate the possibilities of measuring the depth of the surface inhomogeneous layer of steel objects on the basis of the use of amplitude and amplitude-angle characteristics of surface and subsurface transverse waves. The analysis of ultrasonic methods of control of physical and mechanical properties of metals by using surface and subsurface waves and experimentally investigated amplitude-angular characteristics of surface waves, the maximum angle of which increases by 3° at change of dimensionless layer depth hλ from zero to 0.82. For the first time, the ratio of normalized amplitudes of surface waves taken at certain angles on the amplitude-angle characteristic curve obtained in the echo mode was proposed to be used as correlating parameters with the depth of the hardened layer. As a result of this research, the possibility of using a phased array transducers to solve the above problems. The effect of the hardened layer depth varying from zero to five in the working frequency range of 1.8– 10 MHz on the peculiarities of the refraction effect (including interference) and dependence of the subsurface wave amplitude on the acoustic base has been studied, making it possible to establish conditions that provide for the determination of the hardened layer depth. Circuit solutions have been offered in order to increase the efficiency of control of properties of the surface layers of metal articles on the basis of utilization of small-aperture transducers and ultrasonic reflectors making it possible to form fields of surface waves of different directional pattern

    РАСПРОСТРАНЕНИЕ ВОЛНЫ РЭЛЕЯ В ТВЕРДЫХ ТЕЛАХ С ТЕХНОЛОГИЧЕСКИМ ВЫСТУПОМ

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    New distinctive features of the elastic wave excitation and propagation when the Rayleigh wave probes used have been discussed. It was principally shown that such probes can be used not only to find surface defects but to find vertically oriented defects of the low reflection ability. Experimental dependences of the coefficient transformation of Rayleigh wave into edge waves vs. radius of the fillet transition have been got. Influence of the «accompanying» transverse mode excited simultaneously with Rayleigh wave on the resulting acoustic field formation in the projection volume have been investigated. Выявлены особенности возбуждения, распространения и трансформации волны Рэлея в краевые волны на радиусном переходе прямоугольного выступа. Показана принципиальная возможность применения краевых объемных волн для контроля объектов с технологическими выступами и выявления не только поверхностных дефектов, но и дефектов со слабой отражающей способностью, расположенных в объеме выступа. Получены зависимости коэффициента преобразования волны Рэлея в краевые волны при прохождении поверхностной волны по радиусному переходу выступа. Установлено влияние сопутствующей поперечной волны, возбуждаемой совместно с волной Рэлея, на формируемое в объеме выступа результирующее поле.

    Destination development in Western Siberia:Tourism governance and evolutionary economic geography

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    Tourism development has often been identified as a tool for balancing negative effects of economic restructuring, especially in peripheral regions. Tourism-based activities often utilize the availability of abundant nature, but although most English language studies of destination development are presented from western contexts, examples from post-Soviet Russia are rare. Western Siberia is a periphery with access to natural resources and heavy industrialization but remotely located from domestic (Russian) and international markets, where tourism is often considered a saviour, especially for the regional economies. Stakeholders in this Russian resource periphery face challenges in managing governance and cooperation in destinations development due to frequent institutional, economic and social changes. Using evolutionary economic geography and based on primary sources and interview data, tourism development and stakeholder relations are assessed in three Western Siberia regions: Tomsk, Kemerovo and Altai Krai. Findings show that for tourism to make a significant contribution, it must be more central to the economic development agenda in all three regions. However, it is currently only achieving a permanent high-profile in one of them, being crowded out by other (mostly primary) industries in the other two. Although the specific tourism governance set-up varies between the three regions, it is clear that public tourism governance still sits somewhat uneasily between state control and the market economy. Tourism receives substantial public subsidies, especially in large-scale investment projects, which depend on federal support within a governance system where decentralization seems to be somewhat limited and unstable. As a result, the tourism path development in the Siberian periphery is highly dependent on state intervention and success in other sectors.</p

    ТРАНСФОРМАЦИЯ И РАССЕЯНИЕ ПОВЕРХНОСТНЫХ ВОЛН НА АКУСТИЧЕСКОЙ НАГРУЗКЕ ДЛЯ УЛЬТРАЗВУКОВОГО КОНТРОЛЯ И ИЗМЕРЕНИЙ. Ч. 2. Объект исследования – тело с выступом

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    The lack of information about the features of processes of the surface wave's transformation into volume waves and its scattering in metal objects with ledge, slots, grooves and the others is one of the obstacles to improve of the acoustical testing reliability and widening of technical application. The aim of this work was to study of mechanism of acoustical mode's transformation and determination the laws of the fields forming of scatted volume edge wave's in solids with ledge of different geometry and to suggest direction of the study application in area of acoustical testing and measurements.The features of transformation of surface waves into edge transverse and longitudinal wave modes scatted and their fields forming in the volume of the object with ledge vs. its angle of the slope front surface side (0–135°) and a dimensionless transition radius (0–10,2) varied were studied. Theoretical analysis and experimental data shown that in general case the field of the edge transverse waves in the volume of ledge can be imagined as a superposition of the field of edge waves (scatted on ledge) and accompany waves too, radiated simultaneously with the surface waves to radiate. If dimensionless size of the ledge's transition radius lesser than 1 the resulting field of the edge transverse waves is the summary field of two sources. One of them (with small aperture) is localized in the vicinity of the place of intersection of contact surface with ledge's front side surface. As it was found, the second source of the edge transverse waves – the edge head longitudinal waves to appear in the results of transformation of surface waves on the ledge′s radius transition. The structure of the edge acoustic fields including their extremes vs. ledge's angle and its radius transition, position of the surface wave's probe were experimentally studied and theoretically analyzed.Some directions of the results of researches using are the next: а) ultrasonic testing of hard-to-make technological objects in which defects have low sound reflection; b) ultrasonic structure diagnostics of solid (specimens) set far from the ultrasonic by using edge volume transverse and longitudinal modes; c) creation of new ultrasonic arrangements to sound and to receive transverse waves of different polarization.Недостаток информации об особенностях процессов трансформации и рассеяния поверхностных волн в металлоизделиях с выступами, проточками, радиусными переходами и др. сказывается как на достоверности акустического контроля, так и на расширении его технических возможностей. Цель данной работы заключалась в уточнении механизма трансформации упругих мод и закономерностей формирования полей рассеянных краевых объемных волн в объектах с выступами разной геометрии, а также в установлении возможностей использования результатов исследований в области ультразвукового контроля и измерений.Теоретически и экспериментально показано, что результирующее поле объемных мод в объекте с углом выступа 0–135° и безразмерным радиусом радиусного перехода 0–10,2 является суперпозицией поля сопутствующих и трансформированных на выступе из поверхностной волны краевой продольной и поперечной моды, существенно различающихся по направленности и амплитуде. Превалирующий по величине на ~ 10 дБ и более глобальный максимум поля поперечной моды, лежит в окрестности продолжения плоскости контактной поверхности, а обнаруженные при радиусном переходе выступа менее 1 локальные угловые осцилляции поля до ~10–20 дБ обусловлены влиянием отходящей поперечной моды, возникающей при прохождении вдоль поверхности передней грани выступа головной моды.Данные исследований предложено использовать для ультразвукового контроля объектов сложного профиля на наличие слабо отражающих звук дефектов, изучение акустических свойств материалов по данным скорости краевых мод на разных частотах при удаленном расположении их от изучаемого объекта, а также – для излучения-приема поперечной моды разной поляризации

    The Antimicrobial Peptide Histatin-5 Causes a Spatially Restricted Disruption on the Candida albicans Surface, Allowing Rapid Entry of the Peptide into the Cytoplasm

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    Antimicrobial peptides play an important role in host defense against microbial pathogens. Their high cationic charge and strong amphipathic structure allow them to bind to the anionic microbial cell membrane and disrupt the membrane bilayer by forming pores or channels. In contrast to the classical pore-forming peptides, studies on histatin-5 (Hst-5) have suggested that the peptide is transported into the cytoplasm of Candida albicans in a non-lytic manner, and cytoplasmic Hst-5 exerts its candicidal activities on various intracellular targets, consistent with its weak amphipathic structure. To understand how Hst-5 is internalized, we investigated the localization of FITC-conjugated Hst-5. We find that Hst-5 is internalized into the vacuole through receptor-mediated endocytosis at low extracellular Hst-5 concentrations, whereas under higher physiological concentrations, Hst-5 is translocated into the cytoplasm through a mechanism that requires a high cationic charge on Hst-5. At intermediate concentrations, two cell populations with distinct Hst-5 localizations were observed. By cell sorting, we show that cells with vacuolar localization of Hst-5 survived, while none of the cells with cytoplasmic Hst-5 formed colonies. Surprisingly, extracellular Hst-5, upon cell surface binding, induces a perturbation on the cell surface, as visualized by an immediate and rapid internalization of Hst-5 and propidium iodide or rhodamine B into the cytoplasm from the site using time-lapse microscopy, and a concurrent rapid expansion of the vacuole. Thus, the formation of a spatially restricted site in the plasma membrane causes the initial injury to C. albicans and offers a mechanism for its internalization into the cytoplasm. Our study suggests that, unlike classical channel-forming antimicrobial peptides, action of Hst-5 requires an energized membrane and causes localized disruptions on the plasma membrane of the yeast. This mechanism of cell membrane disruption may provide species-specific killing with minimal damage to microflora and the host and may be used by many other antimicrobial peptides

    In Vitro Megakaryocyte Differentiation and Proplatelet Formation in Ph-Negative Classical Myeloproliferative Neoplasms: Distinct Patterns in the Different Clinical Phenotypes

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    Background: Ph-negative myeloproliferative neoplasms (MPNs) are clonal disorders that include primary myelofibrosis (PMF), polycythemia vera (PV) and essential thrombocythemia (ET). Although the pathogenesis of MPNs is still incompletely understood, an involvement of the megakaryocyte lineage is a distinctive feature. Methodology/Principal Findings: We analyzed the in vitro megakaryocyte differentiation and proplatelet formation in 30 PMF, 8 ET, 8 PV patients, and 17 healthy controls (CTRL). Megakaryocytes were differentiated from peripheral blood CD34+ or CD45+ cells in the presence of thrombopoietin. Megakaryocyte output was higher in MPN patients than in CTRL with no correlation with the JAK2 V617F mutation. PMF-derived megakaryocytes displayed nuclei with a bulbous appearance, were smaller than ET- or PV-derived megakaryocytes and formed proplatelets that presented several structural alterations. In contrast, ET- and PV-derived megakaryocytes produced more proplatelets with a striking increase in bifurcations and tips compared to both control and PMF. Proplatelets formation was correlated with platelet counts in patient peripheral blood. Patients with pre-fibrotic PMF had a pattern of megakaryocyte proliferation and proplatelet formation that was similar to that of fibrotic PMF and different from that of ET. Conclusions/Significance: In conclusion, MPNs are associated with high megakaryocyte proliferative potential. Profound differences in megakaryocyte morphology and proplatelet formation distinguish PMF, both fibrotic and prefibrotic, from ET and PV
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