433 research outputs found

    STABILIZATION MEASURES TO IMPROVE THE FINANCIAL MARKET OF UKRAINE

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    The article analyzes the state and dynamics of modern functioning of the financial market of Ukraine, development of legislative, normative and institutional support for realization of the strategy of development of the domestic financial sector in the conditions of an open economic system. Some indicators of activity of banking and non-bank lending institutions were characterized and key problems of their functioning were determined. It has been established that medium- and long-term fiscal policy is dependent on the development of the financial sector, in particular the stock market. The lack of reliable instruments on the domestic securities market is identified, which is a deterrent to the development of institutional participants and hinders the development of the entire financial market. It is substantiated that further development of the financial sector requires strategic measures for its improvement, the definition of a single policy on the development of the financial market at the state level, a reorientation to the creation of domestic investment sources, increased transparency in the adoption of regulatory decisions and the role of associations of market entities, etc. It is noted that the key to stabilization and economic revival of the country is the creation of an effective system of control over the management of national resources and public finances. Corrective actions are proposed to develop the institutional structure of the market, develop its infrastructure, protect shareholders' rights, increase transparency and introduce effective and open regulatory policy and appropriate supervision. Also, a number of measures were proposed for successful implementation of Ukraine's European integration in the financial sector and, in the long run, to ensure macroeconomic stability in Ukraine under the conditions of an open economic system.The article analyzes the state and dynamics of modern functioning of the financial market of Ukraine, development of legislative, normative and institutional support for realization of the strategy of development of the domestic financial sector in the conditions of an open economic system. Some indicators of activity of banking and non-bank lending institutions were characterized and key problems of their functioning were determined. It has been established that medium- and long-term fiscal policy is dependent on the development of the financial sector, in particular the stock market. The lack of reliable instruments on the domestic securities market is identified, which is a deterrent to the development of institutional participants and hinders the development of the entire financial market. It is substantiated that further development of the financial sector requires strategic measures for its improvement, the definition of a single policy on the development of the financial market at the state level, a reorientation to the creation of domestic investment sources, increased transparency in the adoption of regulatory decisions and the role of associations of market entities, etc. It is noted that the key to stabilization and economic revival of the country is the creation of an effective system of control over the management of national resources and public finances. Corrective actions are proposed to develop the institutional structure of the market, develop its infrastructure, protect shareholders' rights, increase transparency and introduce effective and open regulatory policy and appropriate supervision. Also, a number of measures were proposed for successful implementation of Ukraine's European integration in the financial sector and, in the long run, to ensure macroeconomic stability in Ukraine under the conditions of an open economic system

    Density changes of aerosol particles as a result of chemical reaction

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    International audienceThis paper introduces the capability to study simultaneously changes in the density, the chemical composition, the mobility diameter, the aerodynamic diameter, and the layer thickness of multi-layered aerosol particles as they are being altered by heterogeneous chemical reactions. A vaporization-condensation method is used to generate aerosol particles composed of oleic acid outer layers of 2 to 30 nm on 101-nm polystyrene latex cores. The layer density is modified by reaction of oleic acid with ozone for variable exposure times. For increasing ozone exposure, the mobility diameter decreases while the vacuum aerodynamic diameter increases, which, for spherical particles, implies that particle density increases. The aerosol particles are confirmed as spherical based upon the small divergence of the particle beam in the aerosol mass spectrometer. The particle and layer densities are calculated by two independent methods, namely one based on the measured aerodynamic and mobility diameters and the other based on the measured mobility diameter and particle mass. The uncertainty estimates for density calculated by the second method are two to three times greater than those of the first method. Both methods indicate that the layer density increases from 0.89 to 1.12 g·cm?3 with increasing ozone exposure. Aerosol mass spectrometry shows that, concomitant with the increase in the layer density, the oxygen content of the reacted layer increases. Even after all of the oleic acid has reacted, the layer density and the oxygen content continue to increase slowly with prolonged ozone exposure, a finding which indicates continued chemical reactions of the organic products either with ozone or with themselves. The results of this paper provide new insights into the complex changes occurring for atmospheric particles during the aging processes caused by gas-phase oxidants

    Transport of North African dust from the Bodélé depression to the Amazon Basin: a case study

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    Through long-range transport of dust, the North-African desert supplies essential minerals to the Amazon rain forest. Since North African dust reaches South America mostly during the Northern Hemisphere winter, the dust sources active during winter are the main contributors to the forest. Given that the Bodélé depression area in southwestern Chad is the main winter dust source, a close link is expected between the Bodélé emission patterns and volumes and the mineral supply flux to the Amazon. <br><br> Until now, the particular link between the Bodélé and the Amazon forest was based on sparse satellite measurements and modeling studies. In this study, we combine a detailed analysis of space-borne and ground data with reanalysis model data and surface measurements taken in the central Amazon during the Amazonian Aerosol Characterization Experiment (AMAZE-08) in order to explore the validity and the nature of the proposed link between the Bodélé depression and the Amazon forest. <br><br> This case study follows the dust events of 11–16 and 18–27 February 2008, from the emission in the Bodélé over West Africa (most likely with contribution from other dust sources in the region) the crossing of the Atlantic Ocean, to the observed effects above the Amazon canopy about 10 days after the emission. The dust was lifted by surface winds stronger than 14 m s<sup>−1</sup>, usually starting early in the morning. The lofted dust, mixed with biomass burning aerosols over Nigeria, was transported over the Atlantic Ocean, and arrived over the South American continent. The top of the aerosol layer reached above 3 km, and the bottom merged with the boundary layer. The arrival of the dusty air parcel over the Amazon forest increased the average concentration of aerosol crustal elements by an order of magnitude

    Binary pattern tile set synthesis is NP-hard

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    In the field of algorithmic self-assembly, a long-standing unproven conjecture has been that of the NP-hardness of binary pattern tile set synthesis (2-PATS). The kk-PATS problem is that of designing a tile assembly system with the smallest number of tile types which will self-assemble an input pattern of kk colors. Of both theoretical and practical significance, kk-PATS has been studied in a series of papers which have shown kk-PATS to be NP-hard for k=60k = 60, k=29k = 29, and then k=11k = 11. In this paper, we close the fundamental conjecture that 2-PATS is NP-hard, concluding this line of study. While most of our proof relies on standard mathematical proof techniques, one crucial lemma makes use of a computer-assisted proof, which is a relatively novel but increasingly utilized paradigm for deriving proofs for complex mathematical problems. This tool is especially powerful for attacking combinatorial problems, as exemplified by the proof of the four color theorem by Appel and Haken (simplified later by Robertson, Sanders, Seymour, and Thomas) or the recent important advance on the Erd\H{o}s discrepancy problem by Konev and Lisitsa using computer programs. We utilize a massively parallel algorithm and thus turn an otherwise intractable portion of our proof into a program which requires approximately a year of computation time, bringing the use of computer-assisted proofs to a new scale. We fully detail the algorithm employed by our code, and make the code freely available online

    Cloud Condensation Nuclei properties of model and atmospheric HULIS

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    Humic like substances (HULIS) have been identified as a major fraction of the organic component of atmospheric aerosols. These large multifunctional compounds of both primary and secondary sources are surface active and water soluble. Hence, it is expected that they could affect activation of organic aerosols into cloud droplets. We have compared the activation of aerosols containing atmospheric HULIS extracted from fresh, aged and pollution particles to activation of size fractionated fulvic acid from an aquatic source (Suwannee River Fulvic Acid), and correlated it to the estimated molecular weight and measured surface tension. A correlation was found between CCN-activation diameter of SRFA fractions and number average molecular weight of the fraction. The lower molecular weight fractions activated at lower critical diameters, which is explained by the greater number of solute species in the droplet with decreasing molecular weight. The three aerosol-extracted HULIS samples activated at lower diameters than any of the size-fractionated or bulk SRFA. The Köhler model was found to account for activation diameters, provided that accurate physico-chemical parameters are known

    Irreversible impacts of heat on the emissions of monoterpenes, sesquiterpenes, phenolic BVOC and green leaf volatiles from several tree species

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    Climate change will induce extended heat waves to parts of the vegetation more frequently. High temperatures may act as stress (thermal stress) on plants changing emissions of biogenic volatile organic compounds (BVOCs). As BVOCs impact the atmospheric oxidation cycle and aerosol formation, it is important to explore possible alterations of BVOC emissions under high temperature conditions. Applying heat to European beech, Palestine oak, Scots pine, and Norway spruce in a laboratory setup either caused the well-known exponential increases of BVOC emissions or induced irreversible changes of BVOC emissions. Considering only irreversible changes of BVOC emissions as stress impacts, we found that high temperatures decreased the <i>de novo</i> emissions of monoterpenes, sesquiterpenes and phenolic BVOC. This behaviour was independent of the tree species and whether the <i>de novo</i> emissions were constitutive or induced by biotic stress. <br><br> In contrast, application of thermal stress to conifers amplified the release of monoterpenes stored in resin ducts of conifers and induced emissions of green leaf volatiles. In particular during insect attack on conifers, the plants showed <i>de novo</i> emissions of sesquiterpenes and phenolic BVOCs, which exceeded constitutive monoterpene emissions from pools. The heat-induced decrease of <i>de novo</i> emissions was larger than the increased monoterpene release caused by damage of resin ducts. For insect-infested conifers the net effect of thermal stress on BVOC emissions could be an overall decrease. <br><br> Global change-induced heat waves may put hard thermal stress on plants. If so, we project that BVOC emissions increase is more than predicted by models only in areas predominantly covered with conifers that do not emit high amounts of sesquiterpenes and phenolic BVOCs. Otherwise overall effects of high temperature stress will be lower increases of BVOC emissions than predicted by algorithms that do not consider stress impacts

    Absorbing aerosols at high relative humidity: linking hygroscopic growth to optical properties

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    One of the major uncertainties in the understanding of Earth's climate system is the interaction between solar radiation and aerosols in the atmosphere. Aerosols exposed to high humidity will change their chemical, physical, and optical properties due to their increased water content. To model hydrated aerosols, atmospheric chemistry and climate models often use the volume weighted mixing rule to predict the complex refractive index (RI) of aerosols when they interact with high relative humidity, and, in general, assume homogeneous mixing. This study explores the validity of these assumptions. A humidified cavity ring down aerosol spectrometer (CRD-AS) and a tandem hygroscopic DMA (differential mobility analyzer) are used to measure the extinction coefficient and hygroscopic growth factors of humidified aerosols, respectively. The measurements are performed at 80% and 90%RH at wavelengths of 532 nm and 355 nm using size-selected aerosols with different degrees of absorption; from purely scattering to highly absorbing particles. The ratio of the humidified to the dry extinction coefficients (<i>f</i>RH<sub>ext</sub>(%RH, Dry)) is measured and compared to theoretical calculations based on Mie theory. Using the measured hygroscopic growth factors and assuming homogeneous mixing, the expected RIs using the volume weighted mixing rule are compared to the RIs derived from the extinction measurements. <br><br> We found a weak linear dependence or no dependence of <i>f</i>RH(%RH, Dry) with size for hydrated absorbing aerosols in contrast to the non-monotonically decreasing behavior with size for purely scattering aerosols. No discernible difference could be made between the two wavelengths used. Less than 7% differences were found between the real parts of the complex refractive indices derived and those calculated using the volume weighted mixing rule, and the imaginary parts had up to a 20% difference. However, for substances with growth factor less than 1.15 the volume weighted mixing rule assumption needs to be taken with caution as the imaginary part of the complex RI can be underestimated

    On Dice and Coins: Models of Computation for Random Generation

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    AbstractTo examine the concept of random generation in bounded, as opposed to expected, polynomial time, a model of a probabilistic Turing machine (PTM) with the ability to make random choices with any (small) rational bias is necessary. This ability is equivalent to that of being able to simulate rolling any k-sided die (where [k] is polynomial in the length of the input). We would like to minimize the amount of hardware required for a machine with this capability. This leads to the problem of efficiently simulating a family of dice with a few different types of biased coins as possible. In the special case of simulating one n-sided die, we prove that only two types of biased coins are necessary, which can be reduced to one if we allow irrationally biased coins. This simulation is efficient, taking O(log n) coin flips. For the general case we get a tight time vs number of biases tradeoff; for example, with O(log n) different biases, we can simulate, for any i < n, an i-sided die in O(log n) coin flips

    The formation, properties and impact of secondary organic aerosol: current and emerging issues

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    Secondary organic aerosol (SOA) accounts for a significant fraction of ambient tropospheric aerosol and a detailed knowledge of the formation, properties and transformation of SOA is therefore required to evaluate its impact on atmospheric processes, climate and human health. The chemical and physical processes associated with SOA formation are complex and varied, and, despite considerable progress in recent years, a quantitative and predictive understanding of SOA formation does not exist and therefore represents a major research challenge in atmospheric science. This review begins with an update on the current state of knowledge on the global SOA budget and is followed by an overview of the atmospheric degradation mechanisms for SOA precursors, gas-particle partitioning theory and the analytical techniques used to determine the chemical composition of SOA. A survey of recent laboratory, field and modeling studies is also presented. The following topical and emerging issues are highlighted and discussed in detail: molecular characterization of biogenic SOA constituents, condensed phase reactions and oligomerization, the interaction of atmospheric organic components with sulfuric acid, the chemical and photochemical processing of organics in the atmospheric aqueous phase, aerosol formation from real plant emissions, interaction of atmospheric organic components with water, thermodynamics and mixtures in atmospheric models. Finally, the major challenges ahead in laboratory, field and modeling studies of SOA are discussed and recommendations for future research directions are proposed
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