505 research outputs found

    Specific interplanetary conditions for CIR-, Sheath-, and ICME-induced geomagnetic storms obtained by double superposed epoch analysis

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    The comparison of specific interplanetary conditions for 798 magnetic storms with Dst < -50 nT for the period 1976-2000 was made on the basis of the OMNI archive data.We categorized various large-scale types of solar wind as interplanetary drivers of storms: corotating interaction region (CIR), Sheath, interplanetary CME (ICME) including magnetic cloud (MC) and Ejecta, separately MC and Ejecta, and "Indeterminate" type. The data processing was carried out by the method of double superposed epoch analysis which uses two reference times (onset of storm and the minimum Dst index) and make a re-scaling of main phase of storm a such way that after this transformation all storms have equal durations of main phase in new time reference frame. This method reproduced some well-known results and allowed us to obtain some new results. Specifically, obtained results demonstrate high importance of Sheath in generation of magnetic storms as well as a significant differences in properties of MC and Ejecta and in their geoeffectiveness.Comment: 21 pages, 9 figures, 1 table, submitted to J. of Advances in Space Research on 29 July, 2009 for Special Issue "Space Weather Advances

    Delivery features of pregnant women with a uterine scar

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    Vaginal delivery after a Caesarean section remains a controversial topic: there is a lack of reliable data to help doctors and women in labour to determine the best option for delivery during subsequent pregnancy. The review analyzed and summarized the results of the studies devoted to childbirth of pregnant women with scars on the uterus, considered the advantages and disadvantages of vaginal childbirth and repeat Caesarean section, the frequency of complications in the attempt of vaginal childbirth in women with scars on the uterus has been assessed. The modern medical literature available in open sources has been studied: Russian-language scientifc electronic libraries eLibrary and CyberLeninka, Englishlanguage database of medical and biological publications PubMed. It is necessary to consider the data of anamnesis and clinical-instrumental data when choosing the best management tactics of pregnancy and delivery for women with scars on the uterus. Attempting to deliver vaginally helps to reduce maternal and neonatal morbidity, and a large number of studies on this issue should help to reduce the number of unwarranted repeat Caesarean sections. Vaginal delivery after a Caesarean section is an opportunity to avoid severe abdominal surgery and negative consequences associated with repeated Caesarean sections

    Estimating the First-year Corrosion Losses of Structural Metals for Continental Regions of the World

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    The knowledge of the first-year corrosion losses of metals (K1) in various regions of the world is of great importance in engineering applications. The K1 values are used to determine the categories of atmospheric corrosivity, and K1 is also the main parameter in models for the prediction of long-term corrosion losses of metals. In the absence of experimental values of K1, their values can be predicted on the basis of meteorological and aerochemical parameters of the atmosphere using the dose-response functions (DRF). Currently, the DRFs presented in ISO 9223:2012(E) /1/ standard are used for predicting K1 in any region of the world, along with the unified DRFs /2/ and the new DRFs /3/. The predicted values of corrosion losses (K1pr) of carbon steel, zinc, copper and aluminum obtained by various DRFs for various continental regions of the world are presented. In this work we used the atmosphere corrosivity parameters and experimental data on the corrosion losses of metals for the first year of exposure (K1exp) for the locations of the tests performed under the international UN/ECE program, the MICAT project, and the Russian program. For the first time, a comparative assessment of the reliability of various DRFs is given by comparing the values of K1pr and K1ex using graphical and statistical methods. The statistical indicators of reliability of predicting the corrosion losses of metals are calculated for various categories of atmosphere corrosivity. It is shown that the new dose-response functions offer the highest reliability for all categories of atmosphere corrosivity
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