Observation of small scale structure using sextupole lensing

Weak gravitational lensing seeks to determine shear by measuring induced quadrupole (elliptical) shapes in background galaxy images. Small impact parameter (a few kpc) gravitational lensing by foreground core masses between 2 10^{9} and 2 10^{12} M_\odot will additionally induce a sextupole shape with the quadrupole and sextupole minima aligned. This correlation in relative orientation of the quadrupole and sextupole provides a sensitive method to identify images which have been slightly curved by lensing events. A general theoretical framework for sextupole lensing is developed which includes several low order coefficients in a general lensing map. Tools to impute map coefficients from the galaxy images are described and applied to the north Hubble deep field. Instrumental PSFs, camera charge diffusion, and image composition methods are modelled in the coefficient determination process. Estimates of Poisson counting noise for each galaxy are used to cut galaxies with signals too small to reliably establish curvature. Curved galaxies are found to be spatially clumped, as would be expected if the curving were due to small impact parameter lensing by localized ensembles of dark matter haloes. Simulations provide an estimate of the total required lensing mass and the acceptable mass range of the constituent haloes. The overdensities and underdensities of visible galaxies and their locations in the Hubble foreground is found to be consistent with our observations and their interpretation as lensing events.Comment: 40 pages, 44 figure

Опыт использования сетевого курса «Физика» для студентов, обучающихся по дистанционной технологии

The implementation of web course on discipline of Physics into distance learning technologies is discussed. The main stages of web course development and implementation into the educational process have been considered. The web course structure is comprehensive and includes theoretical materials, practical training, and laboratory work. It is shown than implementation of web course into distance learning technologies promotes the accessibility of high quality education for students.Статья посвящена применению сетевого курса по дисциплине «Физика» для студентов, обучающихся по дистанционной технологии. Рассмотрены основные этапы разработки и внедрения сетевого курса в образовательный процесс. Структура сетевого курса носит комплексный характер, включающий в себя теоретический материал, практические занятия и лабораторные практикум. Показано, что внедрение сетевых курсов с использованием дистанционных образовательных технологий способствует обеспечению доступности качественного образования студентов

Role of metallurgical factors in structure and property formation for thick plates of alloys of the Al-Cu-Mg-Mn system

The role of chemical composition is studied in thick plate structure and property formation for alloys of the Al-Cu-Mg-Mn system. It is shown that in order to correct the chemical composition of aluminum alloys it is necessary to consider the alloying element compatible solubility limit within an aluminum matrix at the heating temperature for hardening and the proportion of alloying elements participating in forming almost insoluble phases with impurity elements. An important role is also played by alloying elements formed with reaction of excess phases, although they are soluble but cannot be dissolved during heating for hardening due to saturation of α-solid solution with alloying elements. © 2013 Springer Science+Business Media New York

Phase formation during nonequilibrium crystallization of Al-Mg-Si system alloys

Nonequilibrium crystallization of alloys of the Al-Mg-Si system, and also their structure and phase composition in a cast condition are studied. Thermal analysis is used to establish phase transformation temperature ranges, occurring during nonequilibrium crystallization of industrial aluminum alloys AD31 and AD33. x-Ray microanalysis is used to determine metastable phase composition in the alloys in a cast condition. © 2013 Springer Science+Business Media New York

Types of geoecological research and areas of their application

Planning for the environmental management, construction, as well as forecasting the impact of human activity on the environment, should be carried out based on the provisions of geoecology, which combines relationships in geographical, biological (ecological) and social-production systems. In this case, a systematic approach, as well as knowledge of the links between different systems, will allow us to simulate the level of human impact on the environment and calculate the optimal degree of intervention in its structure. Modern methods of geoecological studies used to assess the impact of human economic activity on the environment are considered, a comparison of geoecological mapping in Russian and foreign studies is carried out, the main stages necessary for conducting geoecological studies are indicated. © 2019 Published under licence by IOP Publishing Ltd.Authors are grateful for the support of experimental works by Act 211 Government Russian Federation, contract no. 02.A03.21.0006

Obtaining statistical data on industrial accidents in Russia

The article investigates the problem of industrial accidents statistical data collecting in Russian Federation. The industrial injuries concealment causes, including those with a fatal outcome, are analyzed. Possible purposes is indicated to use reliable statistics on industrial injuries. © 2020 The Authors, published by EDP Sciences

From D3-Branes to Lifshitz Space-Times

We present a simple embedding of a z=2 Lifshitz space-time into type IIB supergravity. This is obtained by considering a stack of D3-branes in type IIB supergravity and deforming the world-volume by a plane wave. The plane wave is sourced by the type IIB axion. The superposition of the plane wave and the D3-branes is 1/4 BPS. The near horizon geometry of this configuration is a 5-dimensional z=0 Schroedinger space-time times a 5-sphere. This geometry is also 1/4 BPS. Upon compactification along the direction in which the wave is traveling the 5-dimensional z=0 Schroedinger space-time reduces to a 4-dimensional z=2 Lifshitz space-time. The compactification is such that the circle is small for weakly coupled type IIB string theory. This reduction breaks the supersymmetries. Further, we propose a general method to construct analytic z=2 Lifshitz black brane solutions. The method is based on deforming 5-dimensional AdS black strings by an axion wave and reducing to 4-dimensions. We illustrate this method with an example.Comment: version 3: version published in Classical and Quantum Gravit