Returns to Education in Four Transition Countries: Quantile Regression Approach

This paper uses quantile regression techniques to analyze heterogeneous patterns of return to education across the conditional wage distribution in four transition countries. We correct for sample selection bias using a procedure suggested by Buchinsky (2001), which is based on a Newey (1991, 2009) power series expansion. We also examine the empirical implications of allowing for the endogeneity of schooling, using the control function approach proposed by Lee (2007). Using household data from Bulgaria, Russia, Kazakhstan and Serbia in 2003, we show that the return to education is heterogeneous across the earnings distribution. It is also found that accounting for the endogeneity of schooling leads to a higher rate of return to education.sample selection, endogeneity, rate of return to education, quantile regression

Returns to education in four transition countries: Quantile regression approach

This paper uses quantile regression techniques to analyze heterogeneous patterns of return to education across the conditional wage distribution in four transition countries. We correct for sample selection bias using a procedure suggested by Buchinsky (2001), which is based on a Newey (1991, 2009) power series expansion. We also examine the empirical implications of allowing for the endogeneity of schooling, using the control function approach proposed by Lee (2007). Using household data from Bulgaria, Russia, Kazakhstan and Serbia in 2003, we show that the return to education is heterogeneous across the earnings distribution. It is also found that accounting for the endogeneity of schooling leads to a higher rate of return to education

NATURAL AND ARTIFICIAL RADIOACTIVITY IN BULGARIAN SOILS ALONG THE DANUBE RIVER

Data from gamma-spectrometry analyses of soils and sediments samples taken along the Danube river is presented in the paper. Results about the content of natural and artifi cial radionuclides like Sr-90 and Cs-137 are discussed. The region around the Kozloduj NPP including its exclusion zone is investigated in more details. Data from the last years is compared with such from former investigations of similar samples from the region. The soil is a natural depot and initial reservoir for spreading of all man-made radionuclides and natural radioactivity. The man-made isotopes with the longest half-life time, like Sr-90 and Cs-137 are mainly investigated. Because of their feature to be bioelements, that is to include themselves in human’s metabolism, they are especially dangerous when their concentrations in the nutritious chain increase. That is why the investigation of these nuclides together with the natural once like uranium, thorium and radium started in 1978 with annual determination of their concentrations in soils collected from the region of “Kozloduj” NPP and some places along the Danube river potentially exposed to radioactive contamination. The aim was to make a picture of the radioecological status of the soils along the Danube river. The period after 1986 is concerned as the accident in Chernobyl’s NPP changed basically the radioactive situation in the country

ВЛИЯНИЕ НА ПОЧВЕНИТЕ ХАРАКТЕРИСТИКИ ВЪРХУ УСВОЯВАНЕТО НА Ce-144, Ag – 110m, Sb – 125 И Ru – 106 ОТ РАСТЕНИЯТА

The soil special features as a sorbent, its complicated composition and the differences in its characteristics impose the necessity of a research on the uptake of certain radio-isotopes by the plants, cultivated on the most typical soil types of Bulgaria. Carrying this goal a series of cultivation vegetative experiments on fi ve different soil types, with wheat, bean, spinage, turnip and alfalfa were made. After the analysis of the results of the vegetation experiments could be concluded that the transfer of Ce-144, Ag-110m, Sb-125, Ru-106 from the soil into the plants depends on a high extent on the soil characteristics, as the accumulation in the different plants organs considerably differs. After the so made correlation analysis, it was found out the existence of functional dependence between the coeffi cients of transfer for the researched radio-active isotopes and some soil characteristics as pH, consistence of humus, concentration of exchangeable Ca and Mg in the soil, which all is presented below in this research.Особеностите на почвата като сорбент, сложния и състав и различията в свойствата и, налагат изследване на усвояването на радиоизотопите от растения, отглеждани на типични за България почви. За целта бяха изведени серия съдови вегетационни опити върху пет почвени различия, типични за България с ечемик, пшеница, фасул, спанак, репички и люцерна. След направения анализ на резултатите от вегетационните опити, може да се направи изводът, че преминаването на церий-144, сребро-110m, антимон-125, рутений-106 от почва в растенията зависи в значителна степен от свойствата на почвата, като и натрупването в различните органи на растенията се различава съществено. След направения корелационен анализ беше установено съществуването на функционални зависимости межу коефициентите на трансфер за изследваните радиоактивни изотопи и някои характеристики на почвите като рН, съдържание на хумус, концентрацията на обменните катойни на калции и магнезий в почвата, които са представени в статията

ACCUMULATION OF 134CS IN THE PEPPER DEPENDING ON SOIL CHARACTERISTICS AND METHODS FOR REDUCTION OF THE TRANSFER OF RADIONUCLIDES FROM THE SOIL INTO THE VEGETATION PRODUCTION

The particularities of the soil as sorbent, its complex composition and the differences in its properties impose the research of the accumulation of the The development of methods for reduction of the transfer of radionuclides from the soil into the vegetation production being of particular signifi cance for the implementation agricultural activities in conditions of radioactive pollution of the soil, the impact of potassium, calcium and EDTA or ethylenediaminetetraac etic acid over the accumulation of radio-caesium from the soil into the plants. As it is seen from the results presented, the input of potassium, calcium and EDTA in the Orthic Luvisols signifi cantly decreased the input of Сs-134 into the pepper plants.Особеностите на почвата като сорбент, сложния и състав и различията в свойствата и налагат изследването на усвояването на радиоактивните елементи от растения, отглеждани на типични за България почви. От особена важност за провеждането на земеделска дейност в условия на радиактино замърсяване на почвата е разработването на методи за намаляване трансфера на радионуклидите от почвата в растителната продукция, беше изследвано влиянието на калий, калций и ЕДТА върху натрупването на радиоцезия от почвата в растенията. От получените резултати може да се каже, че с внасянето на калий, калций и ЕДТА в сивата горска почва, значително се намалява постъпването на Сs-134 в растенията

Newly Identified Star Clusters in M33. III. Structural Parameters

We present the morphological properties of 161 star clusters in M33 using the Advanced Camera For Surveys Wide Field Channel onboard the Hubble Space Telescope using observations with the F606W and F814W filters. We obtain, for the first time, ellipticities, position angles, and surface brightness profiles for a significant number of clusters. On average, M33 clusters are more flattened than those of the Milky Way and M31, and more similar to clusters in the Small Magellanic Cloud. The ellipticities do not show any correlation with age or mass, suggesting that rotation is not the main cause of elongation in the M33 clusters. The position angles of the clusters show a bimodality with a strong peak perpendicular to the position angle of the galaxy major axis. These results support the notion that tidal forces are the reason for the cluster flattening. We fit King and EFF models to the surface brightness profiles and derive structural parameters including core radii, concentration, half-light radii and central surface brightness for both filters. The surface brightness profiles of a significant number of clusters show irregularities such as bumps and dips. Young clusters (Log age < 8) are notably better fitted by models with no radial truncation (EFF models), while older clusters show no significant differences between King or EFF fits. M33 star clusters seem to have smaller sizes, smaller concentrations, and smaller central surface brightness as compared to clusters in the MW, M31, LMC and SMC. Analysis of the structural parameters presents a age-radius relation also detected in other star cluster systems. The overall analysis shows differences in the structural evolution between the M33 cluster system and cluster systems in nearby galaxies. These differences could have been caused by the strong differences in these various environments.Comment: 30 pages, 12 figures, accepted for publication in MNRA

Wissenschaftliche Monitoringkonzepte für die Deutsche Bucht (WIMO) - Abschlussbericht

The state and development of coastal marine systems and an understanding of the interaction of organisms, sea floor, water column, and biochemical and physical processes can only be obtained by a combination of long-term monitoring and modelling approaches of different complexity. A need for the development and evaluation of monitoring strategies is driven by a framework of different European and German regulations. The research project WIMO (Scientific Monitoring Concepts for the German Bight) has developed concepts and methods that aim at a fundamental scientific understanding of marine systems and also meet monitoring requirements of European legislation and regulations like the EU Marine Strategy Framework Directive. In this final report examples of common descriptors of ecosystem state like seabed integrity, eutrophication, and biodiversity are discussed. It has been assessed to what extent established measuring procedures used to survey the characteristics of the sea floor, and newly developed technologies are eligible for governmental monitoring. The significance of integrative modelling for linking and visualising results of measurements and models is illustrated. It is shown how new concepts have been implemented into governmental monitoring in the form of web based data sheets. These insights enable continuous analyses and developments in the future