187,099 research outputs found
The updated GLE alert system by ANEMOS
No full textGround level enhancements (GLEs) of cosmic radiation are the result of solar energetic particles (SEPs) arriving at the Earth, potentially causing major damage to technological systems, but also posing a threat for human health. Intense SEPs, such as the GLE events, can influence the radiation exposure of aircrafts and consequently increase the radiation dose on human crew, but also have an impact on satellites and affect the design of space missions, i.e electronic devices onboard the satellite platforms etc. Therefore, predicting such events is challenging and one of the most important aspects of space weather research. In this work the updated GLE Alert++ System of the Athens Neutron Monitor Station (A.Ne.Mo.S.) implemented by the Athens Cosmic Ray Group of the National and Kapodistrian University of Athens (NKUA) is being presented. Moreover, the innovations of the updated system in relation to the previous version of the GLE Alert Plus are introduced. Finally, the most recent and the first of solar cycle 25 GLE event, GLE73, is discussed. This event was registered by several stations of the worldwide ground-based neutron monitor network. An accurate alert was issued successfully by the ESA R-ESC federated product GLE Alert Plus, as well as by the updated GLE Alert++ System of the NKUA/A.Ne.Mo.S. It should be emphasized that GLE Alert++ signal by NKUA/A.Ne.Mo.S. was issued 45 minutes earlier than the one issued by GOES satellites
GLE inhibits <i>C. violaceum</i> induced cell-lysis of HepG2 cells.
No full text<p>Phase contrast micrographs at 200X magnification showing (<b>A</b>) lysis of HepG2 cells after 4 h of infection with <i>C. violaceum</i> MTCC 2656 and (<b>B</b>) inhibition of lysis in presence of 400 µg ml<sup>−1</sup> GLE. (<b>C</b>) growth of HepG2 cells in presence of GLE alone (to nullify any effect of GLE on HepG2 growth).</p
Effect of GLE on violacein production and growth of wild-type <i>C. violaceum</i> MTCC 2656 cells.
No full text<p><b>A.</b> Violacein production in the presence of different concentrations of GLE. <b>B.</b> Viable cell number in batch culture grown without (Control) or with (Experimental) supplementation of 400 µg ml<sup>−1</sup>GLE. <b>C</b>. Quantitation of violacein in batch culture grown without (Control) or with (Experimental) supplementation of 400 µg ml<sup>−1</sup> GLE.</p
An Assessment of the GLE Alert++ Warning System
No full textOver the last years the Athens Cosmic Ray Group of the National & Kapodistrian University of Athens has implemented a warning tool called GLE Alert, which is a highly credible application that issues alerts when a ground level enhancement (GLE) starts due to very high energy solar energetic particles reaching the Earth. This application warns of a high intensity solar energetic particle event up to several minutes before it reaches near the near-Earth space environment. In this work, an assessment of the latest updated version of GLE Alert, GLE Alert++, is presented. GLE Alert++ is a federated product of the ESA S2P SWE Space Radiation Expert Service Centre, which is part of the ESA Space WEather Service NETwork (SWESNET) project. The assessment of the GLE Alert++, which was finalized in October 2022, focused on: (a) the availability of the real-time data provided by the neutron monitor stations that contribute to the GLE Alert++, (b) the behaviour of each station regarding the different Alert levels status (Watch, Warning and Alert), and (c) the definition of the real-time assessment index. The results of this work are of essential importance since they ensure a reliable and trustworthy warning tool, and can be highly useful in protecting humans during extreme solar energetic events
Long term ionization effect during several GLE events of solar cycle 23:comparative analysis
No full textAbstract
It is known that the galactic cosmic rays are the main source of ionization in the Earth’s stratosphere and troposphere. Occasionally, with greater probability during solar maximum periods eruptive solar processes, namely solar flares and coronal mass ejections (CMEs) lead to a production of high energy solar energetic particles (SEPs). Special class of events, called ground level enhancements (GLEs) can drastically enhance the atmospheric ionization. The induced by primary cosmic ray particles ionization is important in various processes related to atmospheric physics and chemistry, specifically the minor constituents. During the Solar cycle 23 (1996 May– 2008 January) we observed several strong GLEs, namely the Bastille day event on 14 July 2000 (GLE 59), the Easter event on 15 April 2001 (GLE 60), October–November 2003 Halloween events (GLEs 65, 66 and 67), mid–January 2005 (GLE 68 and 69) and the last event from the cycle on 13 December 2006 (GLE 70) (gle.oulu.fi). Here we study the long term ionization effect of two of the mentioned events (specifically GLE 59 and GLE 70) and perform a comparative analysis, studying the ionization in the tropospheric region. We use a full Monte Carlo 3-D model and compute the cosmic ray induced ionization as a function of the altitude above the sea level. Ionization maps of several altitudes in the troposphere and stratosphere are presented. The investigated ionization effects are much more essential at the altitudes above 12 km a.s.l., and especially in the Regener-Pfotzer maximum (15–20 km) and marginal at altitudes below 8 km
Significantly downregulated <i>C. violaceum</i> genes associated with quorum-sensing and pathogenicity, in presence of GLE.
No full text1<p>gene expression in cells grown for 24 h.</p>2<p>gene expression in cells grown for 24 h in presence of 400 µg ml<sup>−1</sup> of GLE.</p><p>Significantly downregulated <i>C. violaceum</i> genes associated with quorum-sensing and pathogenicity, in presence of GLE.</p
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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