Constraining global properties of the Draco dwarf spheroidal galaxy

By fitting a flexible stellar anisotropy model to the observed surface brightness and line-of-sight velocity dispersion profiles of Draco we derive a sequence of cosmologically plausible two-component (stars + dark matter) models for this galaxy. The models are consistent with all the available observations and can have either cuspy Navarro-Frenk-White or flat-cored dark matter density profiles. The dark matter halos either formed relatively recently (at z~2...7) and are massive (up to ~5x10^9 M_Sun), or formed before the end of the reionization of the universe (z~7...11) and are less massive (down to ~7x10^7 M_Sun). Our results thus support either of the two popular solutions of the "missing satellites" problem of Lambda cold dark matter cosmology - that dwarf spheroidals are either very massive, or very old. We carry out high-resolution simulations of the tidal evolution of our two-component Draco models in the potential of the Milky Way. The results of our simulations suggest that the observable properties of Draco have not been appreciably affected by the Galactic tides after 10 Gyr of evolution. We rule out Draco being a "tidal dwarf" - a tidally disrupted dwarf galaxy. Almost radial Draco orbits (with the pericentric distance <15 kpc) are also ruled out by our analysis. The case of a harmonic dark matter core can be consistent with observations only for a very limited choice of Draco orbits (with the apocentric-to-pericentric distances ratio of <2.5).Comment: 18 pages, 14 figures; accepted by Ap

The Theoretical Approaches to Structural Transformation of National Economic Systems

The article analyzes the current theoretical and methodological approaches to reforming and structural transformation of national economic systems, mainly the national economies of post-socialist space. The influence of non-economic factors on the structural transitional transformations is determined, among which the main emphasis is placed on social factors. In the applied aspect, a model of formation of social environment of the structural transformations of economic systems is proposed, allowing to integrate social factors in the reformation and transformational processes of the State

HIIphot: Automated Photometry of HII Regions Applied to M51

We have developed a robust, automated method, hereafter designated HIIphot, which enables accurate photometric characterization of HII regions while permitting genuine adaptivity to irregular source morphology. HIIphot utilizes object-recognition techniques to make a first guess at the shapes of all sources then allows for departure from such idealized ``seeds'' through an iterative growing procedure. Photometric corrections for spatially coincident diffuse emission are derived from a low-order surface fit to the background after exclusion of all detected sources. We present results for the well-studied, nearby spiral M51 in which 1229 HII regions are detected above the 5-sigma level. A simple, weighted power-law fit to the measured H-alpha luminosity function (HII LF) above log L_H-alpha = 37.6 gives alpha = -1.75+/-0.06, despite a conspicuous break in the HII LF observed near L_H-alpha = 10^38.9. Our best- fit slope is marginally steeper than measured by Rand (1992), perhaps reflecting our increased sensitivity at low luminosities and to notably diffuse objects. HII regions located in interarm gaps are preferentially less luminous than counterparts which constitute M51's grand-design spiral arms and are best fit with a power-law slope of alpha = -1.96+/-0.15. We assign arm/interarm status for HII regions based upon the varying surface brightness of diffuse emission as a function of position throughout the image. Using our measurement of the integrated flux contributed by resolved HII regions in M51, we estimate the diffuse fraction to be approximately 0.45 -- in agreement with the determination of Greenawalt et al. (1998). Automated processing of degraded datasets is undertaken to gauge systematic effects associated with limiting spatial resolution and sensitivity.Comment: 41 pages, 14 figures, Postscript version with high-resolution figures at ftp://ftp.aoc.nrao.edu/staff/dthilker/preprint

To the problems of modeling the brain ischemia in small animals

In the review article the problems of modeling cerebral ischemia in small mammals are consecrated. The advantages of experimental studies that are based on the similarity of the blood circulation of the brain in humans and animals are indicated. Classification of experimental models for the study of acute and chronic disorders of cerebral circulation, mechanisms of their development and preclinical approbation of new drugs is given. The authors indicate that all experimental models of brain ischemia can be divided into two groups: to study risk factors and pathophysiological studies of brain ischemia. And in the second case, the models of focal and global ischemia are described. In conclusion, the authors point out the difficulties and shortcomings of certain methods of ischemia reproduction, which await researchers to solve the above problems

The degeneracy between star-formation parameters in dwarf galaxy simulations and the Mstar-Mhalo relation

We present results based on a set of N-Body/SPH simulations of isolated dwarf galaxies. The simulations take into account star formation, stellar feedback, radiative cooling and metal enrichment. The dark matter halo initially has a cusped profile, but, at least in these simulations, starting from idealised, spherically symmetric initial conditions, a natural conversion to a core is observed due to gas dynamics and stellar feedback. A degeneracy between the efficiency with which the interstellar medium absorbs energy feedback from supernovae and stellar winds on the one hand, and the density threshold for star formation on the other, is found. We performed a parameter survey to determine, with the aid of the observed kinematic and photometric scaling relations, which combinations of these two parameters produce simulated galaxies that are in agreement with the observations. With the implemented physics we are unable to reproduce the relation between the stellar mass and the halo mass as determined by Guo et al. (2010), however we do reproduce the slope of this relation.Comment: Accepted for publication in MNRAS | 12 pages, 8 figure

Natural population movement and COVID-19: data from Russia

The COVID-19 pandemic is highly infectious, so it paralyzed the health systems of many countries causing a high mortality rate. Official data on COVID-19 deaths at many sites are questioned, and the figures are considered several times higher than official data. In this sense, the objective of the study was to determine the impact of the COVID-19 pandemic on the natural movement of the population and, in addition, to evaluate the real mortality rate from COVID-19 in Russia from the construction of predictive mortality models. The study used data from the World Health Organization and the Statistical Service of the Federal State of Russia; se used linear and polynomial models to construct mortality models. The study revealed an underestimation of the official COVID-19 death rate by 2.4 to 6.8 times, depending on the data source. There was a sharp increase in mortality in Russia in 2020 among people over 50 years of age, and with the increase in age, mortality increased. The main reasons for the sharp increase in mortality were coronary heart disease, cerebrovascular diseases, and respiratory diseases, among others

Modern Paradigm of Secured Management of the Development of Complex Hierarchical Systems

The restructuring of the national economy, the processes of transformation taking place in it, actualize the problems of controlled vector development of complex hierarchical systems in the economy. The purpose of this study is to analyze the theoretical and methodological aspects of the development of complex hierarchical systems (CIS) in the economy in the context of unpredictability and stochasticity of the external and internal environment, as well as the uneven development of socioeconomic processes that require controlled vector development. It is the controllability of the vector development of the CIS that makes it possible to ensure the security of the processes of non-linear development of the CIS. The object of the research is the processes of non-linear development of the CIS in the conditions of unpredictability, stochasticity of the external environment and uneven development of socioeconomic processes caused by globalization transformations of the world economy. The study used general and special methods to achieve the goal and solve the tasks. The general methods include the abstract and logical method, which was used to explain the theoretical foundations of the security of the development of complex hierarchical systems, and the methods of theoretical generalization, system and behavioral-economic analysis, which helped to formulate the qualitative goals and objectives of the CIS, identify the problems of managing controlled dynamic processes, conduct a critical analysis of development concepts and find out the genesis of approaches. Special research methods include system-structural analysis, which was used for the formation, selection and implementation of hypotheses, construction of forecasts, and the system approach and methods of analysis and synthesis, which helped to identify and aggregate the qualitative characteristics of the concept of management of secured development of CIS. As a result of the application of these methods, a synergistic approach to the management of CIS processes was achieved and the problems related to stochasticity and uncertainty of the external and internal environment, uneven development of socioeconomic processes and other factors affecting the security of the development of the intellectual economy are addressed. The influence of endogenous and exogenous factors on the development of CIS is substantiated. A methodology based on process-functional management has been proposed to analyze the level of development of the CIS, which can help to increase the efficiency of the use of production resources. The conception of modeling mechanisms for the development of information security systems (ISS) based on the transformation of management processes and investment processes has been developed

The Galactic Distribution of Large HI Shells

We report the discovery of nineteen new HI shells in the Southern Galactic Plane Survey (SGPS). These shells, which range in radius from 40 pc to 1 kpc, were found in the low resolution Parkes portion of the SGPS dataset, covering Galactic longitudes l=253 deg to l=358 deg. Here we give the properties of individual shells, including positions, physical dimensions, energetics, masses, and possible associations. We also examine the distribution of these shells in the Milky Way and find that several of the shells are located between the spiral arms of the Galaxy. We offer possible explanations for this effect, in particular that the density gradient away from spiral arms, combined with the many generations of sequential star formation required to create large shells, could lead to a preferential placement of shells on the trailing edges of spiral arms. Spiral density wave theory is used in order to derive the magnitude of the density gradient behind spiral arms. We find that the density gradient away from spiral arms is comparable to that out of the Galactic plane and therefore suggest that this may lead to exaggerated shell expansion away from spiral arms and into interarm regions.Comment: 25 pages, 20 embedded EPS figures, uses emulateapj.sty, to appear in the Astrophysical Journa