117,566 research outputs found
Flows in the solar atmosphere due to the eruptions on the 15th July, 2002
No full text<p>Which kind of flows are present during flares? Are they compatible with the present understanding of energy release and which model best describes the observations? We analyze successive flare events in order to answer these questions. The flares were observed in the magnetically complex NOAA active region (AR) 10030 on 15 July 2002. One of them is of GOES X-class. The description of these flares and how they relate to the break-out model is presented in Gary & Moore (2004). The Coronal Diagnostic Spectrometer on board SOHO observed this active region for around 14 h. The observed emission lines provided data from the transition region to the corona with a field of view covering more than half of the active region. In this paper we analyse the spatially resolved flows seen in the atmosphere from the preflare to the flare stages. We find evidence for evaporation occurring before the impulsive phase. During the main phase, the ongoing magnetic reconnection is demonstrated by upflows located at the edges of the flare loops (while downflows are found in the flare loops themselves). We also report the impact of a filament eruption on the atmosphere, with flows up to 300 km s<sup>-1</sup> observed at transition-region temperatures in regions well away from the location of the pre-eruptive filament. Our results are consistent with the predictions of the break out model before the impulsive phase of the flare; while, as the flare progresses, the directions of the flows are consistent with flare models invoking evaporation followed by cooling and downward plasma motions in the flare loops.</p>
Biofertilizer and Bioherbicide Potential of Microalgae-Based Wastewater and Diplotaxis harra Boiss for Sustainable Barley Production
No full textThe dual benefit of wastewater and microalgal biomass is a major advantage of high-rate algal ponds, enabling the environmental valorization of these byproducts. This research explored the effect of treated wastewater on the agri-food species Hordeum vulgare (L.) and its associated weed, Emex spinosa (L.) Campd., along with the effects of algal biomass (primarily composed of Closterium, Chlorella, and Scenedesmus spp.) and Diplotaxis harra leaf powder. Initial pot trials applied microalgae and D. harra at 2, 4, and 6 g·kg−1 soil, also confirming that the treated wastewater met reuse standards and did not affect plant growth. The combined treatment at 4 g·kg−1 led to the highest H. vulgare increases in fresh weight (162.71%), root length (73.75%), and shoot length (72.87%), while reducing E. spinosa shoot and root lengths by 30.79% and 52.18%, and fresh weight by 68.24%. Subsequent field experiments using 1.26 t ha−1 of 0.5-cm-applied D. harra and microalgae powders enhanced H. vulgare growth, while reducing the growth of E. spinosa. The reduction in E. spinosa growth was associated with increased electrolyte leakage and malondialdehyde content. These results support the integration of high-rate algal ponds into agriculture, promoting water reuse and reducing reliance on synthetic fertilizers and herbicides in barley production
Isolation and identification of an antibacterial compound from Diplotaxis harra (Forssk.) Boiss
No full textThe emergence of the antibiotic resistance is an ongoing problem in public health, and therefore the search for new natural molecules represents an alternative to synthetic drugs. The aim of this study was to test the antibacterial activity of ten Mediterranean plants (Diplotaxis harra, Ecballium elaterium, Pergularia tomentosa, Myrtus communis, Solanum villosum, Solanum sodomaeum, Peganum harmala, Lepidium sativum, Pistacia lentiscus, and Calendula arvensis) against seven pathogenic bacteria (Staphylococcus aureus, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Klebsiella sp., Salmonella enteritidis, and Bacillus cereus) using the disk diffusion method, in order to isolate and identify the active compound(s). Dichloromethane extract of D. harra flower showed the best activity against S. aureus and L. monocytogenes (MIQ = 30 μg/disk and 15 μg/disk, respectively). This extract was submitted to a bio-guided purification using Thin Layer Chromatography (TLC)-bioautography, and an antibacterial fraction (MIQ = 2 μg/disk) was isolated. The active fraction was characterized by RP-HPLC-DAD-ESI-MSn and GC–MS. Sulforaphane, an isothiocyanate known for its anti-cancer, antioxidant, and anti-inflammatory properties, was identified as antibacterial agent in D. harra for the first time. Due to its high antibacterial activity, sulforaphane could be considered a good candidate for the selection of new natural antibacterial molecules
Properties of EUV and X-ray emission in solar active regions
No full textUsing observations from the Coronal Diagnostic Spectrometer (CDS) on SoHO and the Soft. X-ray Telescope (SXT) on Yohkoh we investigate how the spatial properties of active region emission observed in the EUV and X-ray range varies with temperature. We examine the contrast per unit area of the EUV emission from a number of active regions, and employ correlation techniques and Fourier methods with which we obtain the two dimensional power spectrum of the intensity distribution for a number of images in emission lines formed at different temperatures. Integrating this over polar angle we find isotropic power-law behaviour at all temperatures irt a number of topologically different active regions, with a tendency for flatter spectra at lower temperatures. The existence of power-law spectra indicates that there is no preferred length scale within the regions, at least not a resolvable one, while flatter spectra at lower temperatures indicate that the structures are relatively smaller in this temperature range, possibly providing support for the idea of a multi-component transition region (TR). Implications for various heating models are discussed
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
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
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
Erratum: "Outflows at the edges of active regions: Contribution to solar wind formation?"
No full textFil: Harra, L. K.. Mullard Space Science Laboratory; Reino UnidoFil: Sakao, T.. Institute of Space and Astronautical Science; JapónFil: Mandrini, Cristina Hemilse. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Hara, H.. National Astronomical Observatory of Japan; JapónFil: Imada, S.. National Astronomical Observatory of Japan; JapónFil: Young, P.R.. Rutherford Appleton Laboratory; Reino UnidoFil: van Driel Gesztelyi, Lidia. Centre National de la Recherche Scientifique. Observatoire de Paris; FranciaFil: Baker, D.. Mullard Space Science Laboratory; Reino Unid
Letter from unknown writer to Jesse L. Boyce
No full textLetter to Jesse L. Boyce from unknown author (possibly Jack) about the investigation into the powder magazine located in the Grand Canyon. Some personal news is included in the letter such as the writer's marriage to the daughter of C.A. Taylor, former Supervisor of Cochise County
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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