Nonlinear time-series analysis of Hyperion's lightcurves

Hyperion is a satellite of Saturn that was predicted to remain in a chaotic rotational state. This was confirmed to some extent by Voyager 2 and Cassini series of images and some ground-based photometric observations. The aim of this aticle is to explore conditions for potential observations to meet in order to estimate a maximal Lyapunov Exponent (mLE), which being positive is an indicator of chaos and allows to characterise it quantitatively. Lightcurves existing in literature as well as numerical simulations are examined using standard tools of theory of chaos. It is found that existing datasets are too short and undersampled to detect a positive mLE, although its presence is not rejected. Analysis of simulated lightcurves leads to an assertion that observations from one site should be performed over a year-long period to detect a positive mLE, if present, in a reliable way. Another approach would be to use 2---3 telescopes spread over the world to have observations distributed more uniformly. This may be achieved without disrupting other observational projects being conducted. The necessity of time-series to be stationary is highly stressed.Comment: 34 pages, 12 figures, 4 tables; v2 after referee report; matches the version accepted in Astrophysics and Space Scienc

На пути к автоматизированному мета-анализу биомедицинских текстов в области клеточной иммунотерапии

Cell-based immunotherapy is a promising approach for the treatment of chronic infections, autoimmune disorders, and malignant tumors. There are many strategies of cell-based immunotherapy of cancer; these include injection of various immune effector cells, propagated and «trained» in a cell culture. Alternatively, cells presenting tumor antigens on their surface in a form recognized by the immune system can be used to achieve a therapeutic effect. The research results in this field are presented in thousands of texts, and their manual analysis is very complicated. We have developed an approach for automated text analysis in this area of biomedical science. Here we present the first results of the automated analysis of the data extracted from abstracts of scientific articles available in PubMed. These results demonstrate the associations between types of tumors and the most commonly used methods of their cell-based immunotherapy.Клеточная иммунотерапия это перспективный подход к лечению хронических инфекций, аутоиммунных нарушений и злокачественных опухолей. Существует множество стратегий иммунотерапии рака, включая инъекции различных иммунных эффекторных клеток, размноженных и «обученных» в клеточной культуре. В качестве альтернативы для достижения терапевтического эффекта могут быть использованы клетки, представляющие опухолевый антиген на своей поверхности в «понятном» для иммунной системы виде. Результаты исследований в этой области представлены в тысячах текстов, ручной анализ которых затруднен. Мы разработали подход для автоматического анализа текстов в этой области биомедицинской науки. В данной работе мы представляем первые результаты автоматического анализа данных, извлеченных из абстрактов научных статей, доступных в PubMed. На корпусе извлеченных текстов мы демонстрируем ассоциации между типами опухолей и наиболее часто используемыми способами клеточной терапии

Project Struve

We present the current status of the space astrometry and photometry project STRUVE which is being designed at the Pulkovo Observatory (Russia) in cooperation with other Russian space institutes in order to extend the Hipparcos reference system. This project will include about 20 million stars down to V = 19:5 mag. The proper motions of the Hipparcos stars are to be determined with the mean accuracy of about 0.1 mas/yr. The mean accuracy of star positions in the output catalogue is expected to be better than 0.6 mas. A properly designed micrometer will give the possibility of observing all objects on the sky down to V = 14 mag. Key words: space astrometry; future projects. 1. INTRODUCTION The space astrometry and photometry project Struve (Yershov et al. 1995) is being designed at the Pulkovo Observatory in cooperation with other Russian space institutes. It is expected that launch will be before 2010 and a mission duration of at least 36 months is planned. The main objective is to ex..