849 research outputs found

    Strong variable linear polarization in the cool active star II Peg

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    Magnetic fields of cool active stars are currently studied polarimetrically using only circular polarization observations. Including linear polarization in the reconstruction of stellar magnetic fields allows more information about the magnetic field to be extracted and significantly improves the reliability of stellar magnetic field maps. The goal of this study is to initiate systematic observations of active stars in all four Stokes parameters and to identify cool stars for which linear polarization can be detected at a level sufficient for Zeeman Doppler imaging (ZDI). Four active RS CVn binaries, II Peg, HR 1099, IM Peg, and sigma Gem, were observed with the ESPaDOnS spectropolarimeter at the Canada-France-Hawaii Telescope during a time period from February 2012 to January 2013. The least-squares deconvolution procedure was applied to derive mean polarization profiles of all four Stokes parameters. Linear polarization was detected in all four stars in at least one observation. At the same time, II Peg showed an exceptionally strong and highly variable linear polarization signature throughout all observations. This establishes II Peg as the first promising target for ZDI in all four Stokes parameters and suggests the feasibility of such an analysis with existing equipment for at least a few of the most active cool stars.Comment: 5 pages, 2 figures, 1 table; Accepted for publication in MNRA

    Sublinear Random Access Generators for Preferential Attachment Graphs

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    A Constant Approximation Algorithm for Scheduling Packets on Line Networks

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    European Community Multi-Center Trial "Fetal ECG Analysis During Labor": ST plus CTG analysis

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    This report form part of the European Community Multi-Center Trial "Fetal ECG Analysis during Labor". Aim of this prospective trial was to identify changes in the fetal ECG waveform with cases of verified fetal hypoxia. In this paper we also report on the use of a newly developed automatic system for identification of ST waveform changes (ST Log). All ECG were recorded with the STAN recorder (Neoventa Medical AB, Gothenburg, Sweden). The ECG information was not displayed during labor in order not to influence the clinical management. This report includes data from 320 cases and include six cases of fetal intrapartum hypoxia. Twenty seven cases showed changes in ST waveform. All five cases with the most marked ST change (a rise in T/QRS of >0.10 units and lasting more then 10 minutes) had signs of ongoing intrapartum hypoxia. Six out of six cases with evidence of intrapartum asphyxia, showed ST changes. On the basis of our multi-center trial it appears that the combined analysis of CTG and ST waveform changes provides an accurate way to identify adverse events during labor. The work is continuing with a new STAN recorder developed by Neoventa Medical in Goteborg and currently being tested in a Swedish randomized, controlled multi-center trial

    Dianion diagnostics in DESIREE: High-sensitivity detection of Cn2\text{C}_{n}^{2-} from a sputter ion source

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    A sputter ion source with a solid graphite target has been used to produce dianions with a focus on carbon cluster dianions, Cn2\text{C}_{n}^{2-}, with n=724n=7-24. Singly and doubly charged anions from the source were accelerated together to kinetic energies of 10 keV per atomic unit of charge and injected into one of the cryogenic (13 K) ion-beam storage rings of the Double ElectroStatic Ion Ring Experiment facility at Stockholm University. Spontaneous decay of internally hot Cn2\text{C}_{n}^{2-} dianions injected into the ring yielded C\text{C}^{-} anions with kinetic energies of 20 keV, which were counted with a microchannel plate detector. Mass spectra produced by scanning the magnetic field of a 9090^{\circ} analyzing magnet on the ion injection line reflect the production of internally hot C72C242\text{C}_{7}^{2-}-\text{C}_{24}^{2-} dianions with lifetimes in the range of tens of microseconds to milliseconds. In spite of the high sensitivity of this method, no conclusive evidence of C62\text{C}_{6}^{2-} was found while there was a clear C72\text{C}_{7}^{2-} signal with the expect isotopic distribution. An upper limit is deduced for a C62\text{C}_{6}^{2-} signal that is two orders-of-magnitue smaller than that for C72\text{C}_{7}^{2-}. In addition, CnO2\text{C}_{n}\text{O}^{2-} and CsCu2\text{CsCu}^{2-} dianions were detected.Comment: 6 pages, 6 figure

    Adsorption of CO on a Platinum (111) surface - a study within a four-component relativistic density functional approach

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    We report on results of a theoretical study of the adsorption process of a single carbon oxide molecule on a Platinum (111) surface. A four-component relativistic density functional method was applied to account for a proper description of the strong relativistic effects. A limited number of atoms in the framework of a cluster approach is used to describe the surface. Different adsorption sites are investigated. We found that CO is preferably adsorbed at the top position.Comment: 23 Pages with 4 figure

    Carotenoids and chlorophyll content in natural soap with addition of vegetative raw material

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    In the present study, we performed quantitative and qualitative determination of carotenoids and chlorophyll in five samples of natural soap with addition of vegetative raw material: Green tea, Chamerion angustifolium (L.) Holub, Trifolium pratense L., Alchemilla vulgaris L. and Urtica dioica L. There was developed the method of quantitative content of carotenoids and chlorophyll using spectrophotometry with analytical wavelength at 450 nm (carotenoids) and 667 nm (chlorophyll). Qualitative determination was carried out by the comparative TLC analysis. As mobile phases were used in the experiment following a mixed solvent of hexane-acetone (3: 1). Identification of carotenoids was carried out according to standard samples β -carotene and literature data

    Multivariate Modelling of Pedestrian Fatality Risk Through on the Spot Accident Investigation

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    Pedestrians are the most vulnerable users of public roads and represent one of the largest groups of road casualties; their death rate around the world due to vehicle-pedestrian collisions is high and tending to rise. In Spain, as in other countries of the European Union, steps have been taken to reduce the number and consequences of such accidents, with encouraging results in recent years. A key to countering this concern is the accident research activity that has obtained remarkable achievements in different fields, especially when multidisciplinary approaches are taken. This paper describes the development of a multivariate model that is able to detect the most influential parameters on the consequences of vehicle-pedestrian collision and to quantify their impact on pedestrian fatality risk. First, an accident database containing detailed information and parameters of vehicle-pedestrian collisions in Madrid has been developed. The accidents were investigated on the spot by INSIA accident investigation teams and analyzed using advanced reconstruction techniques. The model was then developed with two components: (1) a classification tree that characterizes and selects the explanatory variables, identifying their interactions, and (2) a binary logistic regression to quantify the influence of each variable and interaction resulting from the classification tree. The whole model represents an important tool for identifying, quantifying and predicting the potential impact of measures aimed at reducing injuries in vehicle-pedestrian collisions
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