Construction of a model of the Venus surface and its use in processing radar observations

An algorithm is described for constructing the model of the Venus surface as an expansion in spherical functions. The relief expansion coefficients were obtained up to the coefficient S sub 99. The surface picture representation is given according to this expansion. The surface model constructed was used for processing radar observations. The use of the surface model allows improved agreement between the design and measured values of radar ranges

Motion Parameters Determination of the SC and Phobos in the Project Phobos-Grunt

The SC "Phobos-Grunt" flight is planned to 2009 in Russia with the purpose to deliver to the Earth the soil samples of the Mars satellite Phobos. The mission will pass under the following scheme [1-4]: the SC flight from the Earth to the Mars, the SC transit on the Mars satellite orbit, the motion round the Mars on the observation orbit and on the quasi-synchronous one [5], landing on Phobos, taking of a ground and start in the direction to the Earth. The implementation of complicated dynamical operations in the Phobos vicinity is foreseen by the project. The SC will be in a disturbance sphere of gravitational fields from the Sun, the Mars and the Phobos. The SC orbit determination is carried out on a totality of trajectory measurements executed from ground tracking stations and measurements of autonomous systems onboard space vehicle relatively the Phobos. As ground measurements the radio engineering measurements of range and range rate are used. There are possible as onboard optical observations of the Phobos by a television system and ranges from the SC up to the Phobos surface by laser locator. As soon as the Phobos orbit accuracy is insufficient for a solution of a problem of landing its orbit determination will be carried out together with determination of the SC orbit. Therefore the algorithms for joint improving of initial conditions of the SC and the Phobos are necessary to determine parameters of the SC relative the Phobos motion within a single dynamical motion model. After putting on the martial satellite orbit, on the Phobos observation orbit, on the quasi-synchronous orbit in the Phobos vicinity the equipment guidance and the following process of the SC orbit determination relatively Phobos requires a priori knowledge of the Phobos orbit parameters with sufficiently high precision. These parameters should be obtained beforehand using both all modern observations and historical ones

Transformation of internal waves at the bottom ledge

Transformation of internal gravity waves on the oceanic shelf is studied theoretically and numerically within the framework of the linear approximation. It is assumed that internal waves pass over the continental shelf experiencing partial transmission and reflection. The problem is studied for the simplified model of the shelf represented by the sharp bottom ledge. The fluid stratification is assumed to be a two-layer with the density of the upper layer being rho_0, and the density of the lower layer being rho_1. The theoretical approximate formulae are proposed for the transmission and reflection coefficients as the functions of an incoming wave number, density ratio, a depth of the interface between the layers, and depth ratio before and after the ledge edge. Results of direct numerical modelling of linear internal waves transformation are presented as functions of all aforementioned parameters. The modelling was undertaken by means of the numerical code MITgcm. The results obtained are analysed in details and compared against the proposed formulae

RadioAstron as a target and as an instrument: Enhancing the Space VLBI mission's scientific output

The accuracy of orbit determination has a strong impact on the scientific output of the Space VLBI mission RadioAstron. The aim of this work is to improve the RadioAstron orbit reconstruction by means of sophisticated dynamical modelling of its motion in combination with multi-station Doppler tracking of the RadioAstron spacecraft. The improved orbital solution is demonstrated using Doppler measurements of the RadioAstron downlink signal and by correlating VLBI observations made by RadioAstron with ground-based telescopes using the enhanced orbit determination data. Orbit determination accuracy has been significantly improved from ~ 600 m in 3D position and ~ 2 cm/s in 3D velocity to several tens of metres and mm/s, respectively.Comment: 8 pages, 8 figures. Astronomy and Astrophysics, accepte

Beyond the KdV: post-explosion development

Several threads of the last 25 years’ developments in nonlinear wave theory that stem from the classical Korteweg–de Vries (KdV) equation are surveyed. The focus is on various generalizations of the KdV equation which include higher-order nonlinearity, large-scale dispersion, and a nonlocal integral dispersion. We also discuss how relatively simple models can capture strongly nonlinear dynamics and how various modifications of the KdV equation lead to qualitatively new, non-trivial solutions and regimes of evolution observable in the laboratory and in nature. As the main physical example, we choose internal gravity waves in the ocean for which all these models are applicable and have genuine importance. We also briefly outline the authors’ view of the future development of the chosen lines of nonlinear wave theory

Open globe eye injury: structure, features of diagnostics and treatment

The following article evaluates results of retrospective analysis of eye traumatism in Sverdlovsk region during 1999-2007. The open globe injuries takes basic place (36% among all eye trauma) in structure of eye damages. Scheme of complex eye injury diagnostics and authors experience of usage are also revealed. Tactics of treatment among patients with double-perforating injuries, subconjunctival retroequatorial scleral ruptures and difficult of access foreign bodies are also shown in the job. Detection of retroequatorial scleral ruptures is the hardest part of diagnostics, therefore authors suggested usage of extra methods like CT, OCT, MRT. Enumerated method combination allows to make diagnostics of double-perforating injuries, subconjunctival scleral ruptures easier and recognize exact localization of damaged structures for opportune surgical treatment, that allows eye preservation.В работе приводятся результаты ретроспективного анализа структуры глазного травматизма в Свердловской области за период с 1999 по 2007 гг., ведущее место в которой занимают открытые травмы глазного яблока (36,0% от общего количества травм). Сообщается о схеме комплексной диагностики данной патологии, используемой авторами, и результатах ее применения. Изложена тактика ведения пациентов с двойными ранениями, субконъюнктивальными разрывами склеры ретроэкваториальной локализации и труднодоступными инородными телами. Наибольшие трудности вызывает обнаружение повреждений заднего отдела склеры, для повышения эффективности диагностики которых авторы предлагают использование по показаниям дополнительных методов — КТ, МРТ и ОКТ. Их использование позволяет не только упростить обнаружение двойных ранений и субконъюнктивальных разрывов склеры, но и достаточно точно диагностировать повреждения внутриглазных и орбитальных структур, что способствует своевременному проведению адекватного хирургического лечения, обеспечивающего сохранение глазного яблока

Clinical case of combined eye injury: penetrating corneoscleral wound with concussion of the third degree. Advanced surgical approach to treatment

The purpose of the study is to present a clinical case of severe combined injury of the eyeball: penetrating corneoscleral injury, concussion of the III degree, as well as an advanced surgical approach to the treatment of this pathology.Цель исследования – представить клинический случай комбинированной травмы глазного яблока: проникающее корнеосклеральное ранение, контузия III степени, а также расширенный хирургический подход к лечению данной патологии

Клинический опыт успешного хирургического лечения гигантской метастатической саркомы легкого

Introduction. Sarcomas refer to a group of heterogeneous non-epithelial malignant tumors originating from connective tissue. These tumors are characterized by extremely aggressive local growth, relatively low incidence of lymphogenic metastases, predominant and early hematogenic generalization. These tumors most oft en metastasize to the lungs.Materials and methods. The paper describes a case of successful surgical treatment for a giant retroperitoneal fibrosarcoma metastasis to the lung.Results. Successful treatment for sarcoma depends primarily on a global understanding by oncologists of the complex pathogenesis, histological forms and principles of comprehensive treatment for this complex, polymorphic group of malignant pathologies. The earlier the primary site is diagnosed, the sooner and more definitely the surgical treatment is performed, and the more correctly the drug therapy is carried out, the better the result of the complex treatment approach. Similarly, sarcoma secondary sites should be treated proactively – without waiting until their size and local spread contraindicate surgical treatment. Conclusion. Neglected sarcoma cases indicate the need for combined and extended surgical interventions, one successful example of which is described in this paper.Введение. Саркомы – группа гетерогенных неэпителиальных злокачественных опухолей, происходящих из соединительной ткани. Данные опухоли характеризуются крайне агрессивным местным ростом, относительно малой частотой лимфогенных метастазов, преимущественной и ранней гематогенной генерализацией. Наиболее часто эти опухоли метастазируют в легкие.Материалы и методы. В статье описан случай успешного хирургического лечения гигантского метастаза фибросаркомы забрюшинного пространства в легкое.Результаты. Успех лечения больных саркомами зависит прежде всего от глобального понимания врачами-онкологами сложных вопросов патогенеза, гистологических форм и принципов комплексной терапии этой сложной, полиморфной группы злокачественной патологии. Чем более рано диагностирован первичный очаг, чем скорее и радикальнее выполнено хирургическое лечение и чем более верно проведена лекарственная терапия, тем лучше результат комплексного лечебного подхода. Аналогичным образом следует действовать и при вторичных очагах саркомы, не дожидаясь момента, когда их размеры и местное распространение будут являться противопоказанием к хирургическому лечению.Заключение. Запущенные случаи сарком диктуют необходимость комбинированных и расширенных хирургических вмешательств, один из успешных примеров которых описан в данной статье

An optimal transient growth of small perturbations in thin gaseous discs

A thin gaseous disc with an almost keplerian angular velocity profile, bounded by a free surface and rotating around point-mass gravitating object is nearly spectrally stable. Despite that the substantial transient growth of linear perturbations measured by the evolution of their acoustic energy is possible. This fact is demonstrated for the simple model of a non-viscous polytropic thin disc of a finite radial size where the small adiabatic perturbations are considered as a linear combination of neutral modes with a corotational radius located beyond the outer boundary of the flow.Comment: 15 pages, 5 figures, accepted for publication in Ast