Inversionless gain in a three-level system driven by a strong field and collisions

Inversionless gain in a three-level system driven by a strong external field and by collisions with a buffer gas is investigated. The mechanism of populating of the upper laser level contributed by the collision transfer as well as by relaxation caused by a buffer gas is discussed in detail. Explicit formulae for analysis of optimal conditions are derived. The mechanism developed here for the incoherent pump could be generalized to other systems.Comment: RevTeX, 9 pages, 4 eps figure

Formation of plasma around a small meteoroid: 1. Kinetic theory

This article is a companion to Dimant and Oppenheim [2017] https://doi.org/10.1002/2017JA023963.This paper calculates the spatial distribution of the plasma responsible for radar head echoes by applying the kinetic theory developed in the companion paper. This results in a set of analytic expressions for the plasma density as a function of distance from the meteoroid. It shows that at distances less than a collisional mean free path from the meteoroid surface, the plasma density drops in proportion to 1/R where R is the distance from the meteoroid center; and, at distances much longer than the mean‐free‐path behind the meteoroid, the density diminishes at a rate proportional to 1/R2. The results of this paper should be used for modeling and analysis of radar head echoes.This work was supported by NSF grant AGS-1244842. (AGS-1244842 - NSF

Combination of hypomorphic mutations of the Drosophila homologues of aryl hydrocarbon receptor and nucleosome assembly protein family genes disrupts morphogenesis, memory and detoxification

Aryl hydrocarbon receptor is essential for biological responses to endogenous and exogenous toxins in mammals. Its Drosophila homolog spineless plays an important role in fly morphogenesis. We have previously shown that during morphogenesis spineless genetically interacts with CG5017 gene, which encodes a nucleosome assembly factor and may affect cognitive function of the fly. We now demonstrate synergistic interactions of spineless and CG5017 in pathways controlling oxidative stress response and long-term memory formation in Drosophila melanogaster. Oxidative stress was induced by low doses of X-ray irradiation of flies carrying hypomorphic mutation of spineless, mutation of CG5017, and their combination. To determine the sensitivity of these mutants to pharmacological modifiers of the irradiation effect, we irradiated flies growing on standard medium supplemented by radiosensitizer furazidin and radioprotector serotonin. The effects of irradiation were investigated by analyzing leg and antenna morphological structures and by using real-time PCR to measure mRNA expression levels for spineless, Cyp6g1 and Gst-theta genes. We also examined long-term memory in these mutants using conditioned courtship suppression paradigm. Our results show that the interaction of spineless and CG5017 is important for regulation of morphogenesis, long-term memory formation, and detoxification during oxidative stress. Since spineless and CG5017 are evolutionary conserved, these results must be considered when evaluating the risk of combining similar mutations in other organisms, including humans

Компьютерная лексикография: традиционные и современные методологии

Nowadays there are a lot of modern technologies in electronic lexicography: speech synthesis technology, crossreferencing between dictionary modules, spell-checking functions, etc. The increasing availability of online information has necessitated intensive research in the area of automatic text summarization within the Natural Language Processing community. Belarusian scientists are also interested in this sphere and new lexicographical approaches for creating a linguistic database are shown in the paper. The authors present English-Belarusian-Russian electronic dictionary TechLex. This is the project of the 2nd English Department and the Department of Software for Information Systems and Technologies of the Belarusian National Technical University. The linguistic database of the dictionary is compiled not by the traditional method of processing a large number of paper dictionaries and combining the received translations, but by sequential processing of scientific and technical English-language periodicals. While the designing the dictionary the authors have taken into account the analysis of modern electronic multilingual translation dictionaries and created a client-server application in the Java programming language. The client part of the system contains a mobile application for the Android operating system, which has been tested on tablets and smartphones with different screen diagonals. The interface of the TechLex dictionary is designed taking into account the possibility of adding new subject areas and filling them with appropriate lexical material. The main advantage of our dictionary is that it is the first technical multilingual electronic dictionary having a Belarusian version

Multidimensional integration of RDF datasets

Data providers have been uploading RDF datasets on the web to aid researchers and analysts in finding insights. These datasets, made available by different data providers, contain common characteristics that enable their integration. However, since each provider has their own data dictionary, identifying common concepts is not trivial and we require costly and complex entity resolution and transformation rules to perform such integration. In this paper, we propose a novel method, that given a set of independent RDF datasets, provides a multidimensional interpretation of these datasets and integrates them based on a common multidimensional space (if any) identified. To do so, our method first identifies potential dimensional and factual data on the input datasets and performs entity resolution to merge common dimensional and factual concepts. As a result, we generate a common multidimensional space and identify each input dataset as a cuboid of the resulting lattice. With such output, we are able to exploit open data with OLAP operators in a richer fashion than dealing with them separately.This research has been funded by the European Commission through the Erasmus Mundus Joint Doctorate Information Technologies for Business Intelligence-Doctoral College (IT4BI-DC) program.Peer ReviewedPostprint (author's final draft

The physical and mechanical characteristics of cast steel 20ГЛ after electric spark alloing and ultrasonic impact treatment

Досліджено мікротвердість, структуру, фазовий склад і корозійну стійкість низьколегованої ливарної сталі 20ГЛ у вихідному стані після стандартної термообробки, а також після електроіскрового легування(ЕІЛ) різними елементами (Ni, Cr, Mo) і ультразвукової ударної обробки (УЗУО). Великий розмір феритної і перлітної складових обумовлює суттєву різницю між значеннями мікротвердості сталі як у вихідному, так і деформованому станах. Застосування ЕІЛ призводить до суттєвішого зміцнення, ніж УЗУО, особливо у випадку легування хромом та молібденом. Це зумовлено складними фазовими та структурними перетвореннями, які протікають при комбінованій обробці ЕІЛ+УЗУО: формування ОЦК твердих розчинів Fe-Cr і Fe-Mo, зміцнених інтерметалідними та карбідними фазами. Шорсткість поверхонь зразків при цьому значно знижувалась. Усі сформовані поверхневі шари на сталі 20ГЛ, леговані нікелем, хромом та молібденом, характеризуються більшим потенціалом корозії та меншим струмом корозії в порівнянні зі стальними зразками у вихідному стані, що свідчить про їх вищу стійкість до електрохімічної корозії. Згідно з аналізом морфології кородованих поверхонь найефективнішим виявилось ЕІЛ поверхневого шару нікелем, яке призводить до формування в ньому ГЦК твердого розчину залізо-нікель.Microhardness, structure, phase composition and corrosion resistance of low alloyed cast 20GL steel are studied in initial state after standard heat treatment, and after the electro-sparking alloying (ESA) by different elements (Ni, Cr, Mo) and ultrasonic impact treatment (UIT). Relatively large size of ferritic and pearlitic constituents determines a substantial difference between the microhardness values of the steel both in initial and in deformed states. The UIT process leads to slight increase in microhardness, and for the specimen after the UIT processing for 60 s the microhardness becomes 4 GPa, which is 1.45 times higher than that for initial state. Application of the ESA+UIT results in more substantial hardening than UIT, especially in the case of alloying with chromium (5.81 GPa) and molybdenum (7.47 GPa), which are 2.0 – 3.5 times and 2.7 – 4.3 times higher than initial specimen, respectively. It is due to complex phase and structural transformations, which occur at the combined ESA+UIT treatment. The ESA processes with chromium and molybdenum leads to formation of BCC Fe-Cr and Fe-Mo solid solutions strengthened by intermetallic phases and/or chromium-iron carbides. Using the nickel electrode at the ESA process promotes formation the FCC Fe-Ni solid solution. In all the cases, the UIT process decreases the surface roughness of specimens considerably. All the formed superficial layers on the 20GL steel, alloyed with nickel, chromium and molybdenum are characterized by higher corrosion potential and lower corrosion current in comparison with the initial steel specimens that testifies to their higher resistances to electrochemical corrosion. According to the analysis of morphology of corroded surfaces the ESA process of superficial layer with nickel electrode is the most effective one, which leads to formation the iron-nickel FCC solid solution. The superficial layers alloyed with chromium and molybdenum underwent more severe corrosion attack due to their heterogenic phase structure. Considerable misfit between lattices of BCC solid solutions (Fe-Cr or Fe-Mo) and intermetallic or carbide phases with crystalline lattices of low symmetry results in formation of defects and stresses can also promote higher corrosion rate

Cannibalism as a life boat mechanism

Under certain conditions a cannibalistic population can survive when food for the adults is too scarce to support a non-cannibalistic population. Cannibalism can have this lifeboat effect if (i) the juveniles feed on a resource inaccessible to the adults; and (ii) the adults are cannibalistic and thus incorporate indirectly the inaccessible resource. Using a simple model we conclude that the mechanism works when, at low population densities, the average yield, in terms of new offspring, due to the energy provided by one cannibalized juvenile is larger than one

Application of an Equilibrium Vaporization Model to the Ablation of Chondritic and Achondritic Meteoroids

We modeled equilibrium vaporization of chondritic and achondritic materials using the MAGMA code. We calculated both instantaneous and integrated element abundances of Na, Mg, Ca, Al, Fe, Si, Ti, and K in chondritic and achondritic meteors. Our results are qualitatively consistent with observations of meteor spectra.Comment: 8 pages, 4 figures; in press, Earth, Moon, and Planets, Meteoroids 2004 conference proceeding

Study on early inflorescence development in bread wheat (T. aestivum L.) lines with non-standard SCR-morphotype

Features of wheat (Triticum aestivum L.) inflorescence development define its architecture and have an impact on yield potential. Wheat lines and forms with altered inflorescence morphology are important genetic resources for the study on the genetic mechanisms underlying plant developmental programs and inflorescence architecture; they are also important for practical use to increase productivity. Normally, wheat spikelets are arranged in two parallel rows along the spike axis. The SCR (screwed spike rachis) lines represent a non-standard morphotype, which is characterized by a spiral arrangement of spikelets along the spiked rachis. The study of the early stages of the inflorescence development in SCR-lines using light and scanning electron microscopy revealed that the spiral arrangement of spikelets were not related to changes at the early stage of inflorescence development, and resulted from spiral growth of spike rachis cells at later stages of spike growth. Thus, the spiral arrangement of spikelets in cereal inflorescence may have resulted not only from peculiarities of the mutual arrangement of spikelet meristems (phyllotaxis), but also from cell growth features at later stages of inflorescence growth. It was shown that SCR is inherited as a dominant monogenic trait; its expression can be modified by genotypic background. The SCR-lines characterized using light and scanning electron microscopy represent an important genetic resource for further study of the molecular-genetic mechanisms determining plant architecture. Furthermore, they can be used to develop wheat lines and cultivars with new inflorescence phenotypes