605 research outputs found
ON THE BELETSKY EQUATION
No full textThis paper was presented at the Beletsky Session of the 4th IAA Conference on University Satellite Missions and CubeSat Workshop held in Rome and dedicated to the memory of the great Russian mathematician and pioneer scientist of Astrodynamics. The paper is concentrated to the so called Beletsky equation, concerning the attitude motion of a satellite under gravity gradient torque. In fact Professor Beletsky dealt with many aspects of astrodynamics giving deep and useful contributions and establishing some theoretical basis for the development of the space activity in USSR, then it looks like disappointing that his name is so strictly linked to a simple equation such as(1 + e cos theta)theta '' - 2e sin theta ' + alpha sin theta = 4e sin thetadescribing the planar attitude motion of a satellite in elliptic orbit: The reason of the enormous success of the Beletsky equation is just in its simplicity and in the interesting characteristics of its phase space, where regular and periodic solutions are merged together with unstable and chaotic solutions. This is not unusual for a non linear differential equation, but in the Beletsky equation these characteristics can be understood in deep and the transition to chaos can be checked by various indices, so many researchers were attracted by the results that can be achieved from the abstract point of view of dynamical system theory while obtaining output of concrete interest in space applications. Most of the content presented in this paper is derived from my PhD thesis "Chaos in Astrodymanics" presented at the School of Aerospace Engineering of Rome in 1991 and developed under the supervision of Professor Filippo Graziani
Report on the ESO Workshop ''Spiral Structure in the Milky Way: Confronting Observations and Theory''
No full textThe main objectives of the workshop were to review current observational evidence for spiral arms in our Galaxy and confront them with models of spiral structure in order to arrive at a consistent picture. Of primary importance was to understand just what additional information is required to resolve outstanding issues related to the spiral structure in the Milky Way, especially as new survey instruments (e.g., ALMA, VISTA and VST) are coming online and major space missions like GAIA will be launched in the near future
Five old open clusters more in the outer Galactic disc
No full textNew photometric material is presented for six outer disc supposedly old, Galactic star clusters: Berkeley 76, Haffner 4, Ruprecht 10, Haffner 7, Haffner 11 and Haffner 15, which are projected against the rich and complex Canis Major overdensity at 225° ≤ l ≤ 248°, -7° ≤ b ≤ -2°. This CCD data set, in the UBVI passbands, is used to derive their fundamental parameters, in particular age and distance. Four of the program clusters turn out to be older than 1 Gyr. This fact makes them ideal targets for future spectroscopic campaigns aiming at deriving their metal abundances. This, in turn, contributes to increase the number of well-studied outer disc old open clusters. Only Haffner 15, previously considered an old cluster, is found to be a young, significantly reddened cluster, member of the Perseus arm in the third Galactic quadrant. As for Haffner 4, we suggest an age of about half a Gyr. The most interesting result we found is that Berkeley 76 is probably located at more than 17 kpc from the Galactic centre, and therefore is among the most peripherical old open clusters so far detected. Besides, for Ruprecht 10 and Haffner 7, which were never studied before, we propose ages larger than 1 Gyr
The red-winged blackbird : the biology of a strongly polygynous songbird /
No full textThe red-winged blackbird is not only one of North America's commonest birds, but also its best studied. It exemplifies the contribution that in-depth species studies can make to many of the central issues in behavioral ecology. In this book, Les Beletsky calls on 20 years experience of redwings to provide an up-to-date, comprehensive summary of all the major work done with these birds. These studies on the redwings' polygynous breeding system, strong territoriality, complex vocal communications, and broad distribution shed light on many themes of key interest to behaviorists and ecologists interested in the evolution of mate choice and species adaptations to habitats which vary in character in different parts of their range. An extra dimension is added in the consideration of redwings as pests, a widespread and often serious problem in crops of rice and corn. This book is written in an easy style, and will serve as an introduction, to both student and layperson, to redwings and what they can teach us of behavioural ecology. The red-winged blackbird provides the research worker with a balanced summary and comprehensive bibliography of one of ornithology's widest and deepest studies.Includes bibliographical references (pages 289-307) and index.The red-winged blackbird is not only one of North America's commonest birds, but also its best studied. It exemplifies the contribution that in-depth species studies can make to many of the central issues in behavioral ecology. In this book, Les Beletsky calls on 20 years experience of redwings to provide an up-to-date, comprehensive summary of all the major work done with these birds. These studies on the redwings' polygynous breeding system, strong territoriality, complex vocal communications, and broad distribution shed light on many themes of key interest to behaviorists and ecologists interested in the evolution of mate choice and species adaptations to habitats which vary in character in different parts of their range. An extra dimension is added in the consideration of redwings as pests, a widespread and often serious problem in crops of rice and corn. This book is written in an easy style, and will serve as an introduction, to both student and layperson, to redwings and what they can teach us of behavioural ecology. The red-winged blackbird provides the research worker with a balanced summary and comprehensive bibliography of one of ornithology's widest and deepest studies
Art Critic, Artist and Teacher Platon Beletsky (the 80th anniversary of his birth)
No full textЙдеться про історика мистецтва, художника і педагога Платона Білецького (1922-1998). Характерною особливістю є розробка ним декількох тем: творчість Г. Нарбута і Т. Шевченка, український портрет ХVІІ- ХVІІІ ст. Відмічається послідовний історизм мислення вченого.The article is about the art historian, artist and teacher Platon Beletsky (1922-1998). A characteristic feature of the article is the development of its several themes: G. Narbut’s and Shevchenko’s creativity, Ukrainian portrait of the seventeenth and eighteenth centuries. The consistent historicism of scientist’s thinking is noted
Model-independent diagnostics of highly reddened Milky Way star clusters: age calibration
No full textContext: The next generation near- and mid-infrared Galactic surveys will yield a large number of new highly obscured star clusters. Detailed characterization of these new objects with spectroscopy is time-consuming.
Aims: Diagnostic tools that will be able to characterize clusters based only on the available photometry will be needed to study large samples of the newly found objects.
Methods: The brightness difference between the red clump and the main-sequence turn-off point have been used as a model-independent age calibrator for clusters with ages from a few 108 to 1010 yr in the optical. Here we apply for the first time the method in the near-infrared.
Results: We calibrated this difference in K-band, which is likely to be available for obscured clusters, and we apply it to a number of test clusters with photometry comparable to the one that will be yielded by the current or near-future surveys.
Conclusions: The new calibration yields reliable ages over the range of ages for which the red clump is present in clusters. The slope of the relation is smoother than that of the corresponding V-band relation, reducing the uncertainty in the age determinations with respect to the optical ones
Estudio en el infrarrojo cercano de agrupaciones estelares en M 83
No full textNear infrared photometric observations (JHKBr) have been made in the field of the galaxy M 83, reaching a magnitude limit K = 20. The quality of data has allowed the systematic search and identification of large numbers of stellar clusters which are intended to determine their fundamental param- eters, as the number of prospective members, reddening, age and luminosity function
DS_10.1177_0363546519851506 – Supplemental material for Analysis of Return to Sport and Weight Training After Repair of the Pectoralis Major Tendon
No full textSupplemental material, DS_10.1177_0363546519851506 for Analysis of Return to Sport and Weight Training After Repair of the Pectoralis Major Tendon by Joseph N. Liu, Anirudh K. Gowd, Grant H. Garcia, Brandon J. Manderle, Alexander Beletsky, Gregory P. Nicholson, Brian Forsythe, Anthony A. Romeo and Nikhil N. Verma in The American Journal of Sports Medicine</p
DS_10.1177_0363546519881638 – Supplemental material for Return to Work and Sport After Proximal Tibial Osteotomy and the Effects of Opening Versus Closing Wedge Techniques on Adverse Outcomes: A Systematic Review and Meta-analysis
No full textSupplemental material, DS_10.1177_0363546519881638 for Return to Work and Sport After Proximal Tibial Osteotomy and the Effects of Opening Versus Closing Wedge Techniques on Adverse Outcomes: A Systematic Review and Meta-analysis by Kyle N. Kunze, Alexander Beletsky, Charles P. Hannon, Robert F. LaPrade, Adam B. Yanke, Brian J. Cole, Brian Forsythe and Jorge Chahla in The American Journal of Sports Medicine</p
DTHA as a Smithery of Art Specialists
No full textУ статті вихованця Київського державного художнього інституту йдеться про факультет теорії та історії мистецтва. Автор згадує викладачів кафедри факультету, які читали курси з історії мистецтва у 1970-х-поч.1980-х рр. (П. Білецький, А. Заварова, П. Говдя, В. Клєваєв та ін.), які відіграли значну роль у навчальному процесі.
Article of educatee of Kiev State Art Institute is talking about the theory and history of art. The author mentions the department teachers, who read courses in art history in the 1970s-early 1980's (P. Beletsky, A. Zavarova, P. Hovdya, V. Klyevayev et al.), who played a significant role in the learning process
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