283 research outputs found

    Daytime Electron Density At the F1-Region in Europe During Geomagnetic Storms

    Get PDF
    This study attempts to demonstrate changes in the ionospheric F1-region daytime ionization during geomagnetic storms. The F1-region is explored using available data from several European middle latitude and lower latitude observatories and a set of geomagnetic storms encompassing a range of seasons and solar activity levels. The results of analysis suggest systematic seasonal and partly latitudinal differences in the F1-region response to geomagnetic storm. The pattern of the response of the F1-region at higher middle latitudes, a decrease in electron density, does not depend on the type of response of the F2-region and on solar activity. A brief interpretation of these findings is presented

    Improvement of IRI B0, B1 and D1 at mid-latitude using MARP

    Get PDF
    Comparative analysis of predicted parameters B0, B1 and D1 by IRI-2001model (International Reference Ionosphere) and those obtained from the Monthly Averaged Representative Profiles (MARP) at mid-latitude station shows significant disagreement. The linear coefficient of determination between the model-predicted and expected (MARP) values are about R 2 ∼ 0.45, 0.22, and 0.15 for B0, B1 and D1, respectively. A Local Model (LM) created using a general least-square fit to a harmonic function of these parameters obtained by MARP simulating the diurnal, semidiurnal and seasonal variations improves the linear coefficient of determination between the expected and IRI-predicted parameters by factor of two. The coefficients obtained from this model could be implemented into the IRI software to improve calculations of the parameters B0, B1 and D1.Fil: Blanch, E.. Universitat Ramon Llull; EspañaFil: Arrazola, D.. Universitat Ramon Llull; EspañaFil: Altadill, D.. Universitat Ramon Llull; EspañaFil: Buresova, D.. Academy Of Sciences Of The Czech Republic. Institute Of Atmospheric Physics; República ChecaFil: Mosert, Marta Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Complejo Astronómico "El Leoncito". Universidad Nacional de Córdoba. Complejo Astronómico "El Leoncito". Universidad Nacional de la Plata. Complejo Astronómico "El Leoncito". Universidad Nacional de San Juan. Complejo Astronómico "El Leoncito"; Argentin

    Searching for effects caused by thunderstorms in midlatitude sporadic E layers

    Get PDF
    Possible thunderstorm - sporadic E (Es) layer coupling effects are investigated during two measurement periods, one in 2013 and one in 2014. The analysis was based on ionospheric observations obtained from a Digisonde at Pruhonice, the Czech Republic, an ionosonde at Nagycenk, Hungary, and a 3.59 MHz five-point continuous HF Doppler system located in the western part of the Czech Republic. The latter is capable of detecting ionospheric wave-like variations caused by neutral atmospheric waves generated by thunderstorms. The present study searches for possible impacts on Es layers caused by the presence of two active thunderstorms: one passing across the Czech Republic on June 20, 2013 (19:00 - 01:00 LT), and one through Hungary on July 30, 2014 (11:00 - 01:00 LT). During these two time periods, presence and parameters of Es layer were inferred from ionograms, recorded every minute at Pruhonice and every two minutes at Nagycenk, whereas concurrent lightning activity was monitored by the LINET detection network. In addition, transient luminous events (TLEs) were also observed during both nights from Sopron, Hungary and from Nydek, the Czech Republic. A noticeable fact was the reduction and disappearance of the ongoing Es layer activity during part of the time in both of the traversing thunderstorms. The analysis indicated that the critical frequency foEs dropped below ionosonde detection levels in both cases, possibly because of thunderstorm activity effects. This option, however, needs more case studies in order to be further substantiated

    Assessing the quality of ionogram interpretation using the HF Doppler technique

    Get PDF
    International audienceThe first joint common volume measurements by the Digisonde Portable Sounder (DPS-4) and a new Doppler type system has been run at the Pruhonice ionospheric observatory (49.99° N, 14.54° E) since January 2004. The measurement of the Doppler shift is carried out continuously on a frequency of 3.6 MHz, thus the radio wave is reflected predominantly from the ionospheric F layer. To compare digisonde measurements with the Doppler data, a phase path was calculated from both Doppler and digisonde records. Under stormy conditions and in the case where a sporadic E layer was present, a significant disagreement between both measurements has been found. The discrepancies could be related to the uncertainties of the observational inputs and to the interpretation of the digisonde data. The comparison of the phase paths shows that during geomagnetically quiet days, in the absence of the sporadic E layer, and when high quality ionograms are available and correctly scaled, the electron density N(h) profiles, calculated by the Automatic Real Time Ionogram Scaler with True height algorithm (ARTIST), can be considered reliable

    Successful management of a solitary simple renal cyst in a dog

    Get PDF
    In this report, a dog is described that was referred to the Small Animal Department, Faculty of Veterinary Medicine (Ghent University) for further work-up and treatment of a solitary renal cyst. The cyst was treated successfully with ultrasound-guided drainage and percutaneous sclerotherapy. The dog was followed-up during twenty-four months post procedure with renal sonography. The complaints of intermittent lethargy disappeared after the first treatment. The ultrasonographic appearance of the cyst evolved from a round, anechoic, sharply demarcated lesion to an ill-defined, hyperechoic lesion

    Molecular organization and comparative analysis of chromosome 5B of the wild wheat ancestor Triticum dicoccoides

    Get PDF
    Wild emmer wheat, Triticum turgidum ssp. dicoccoides is the wild relative of Triticum turgidum, the progenitor of durum and bread wheat, and maintains a rich allelic diversity among its wild populations. The lack of adequate genetic and genomic resources, however, restricts its exploitation in wheat improvement. Here, we report next-generation sequencing of the flow-sorted chromosome 5B of T. dicoccoides to shed light into its genome structure, function and organization by exploring the repetitive elements, protein-encoding genes and putative microRNA and tRNA coding sequences. Comparative analyses with its counterparts in modern and wild wheats suggest clues into the B-genome evolution. Syntenic relationships of chromosome 5B with the model grasses can facilitate further efforts for fine-mapping of traits of interest. Mapping of 5B sequences onto the root transcriptomes of two additional T. dicoccoides genotypes, with contrasting drought tolerances, revealed several thousands of single nucleotide polymorphisms, of which 584 shared polymorphisms on 228 transcripts were specific to the drought-tolerant genotype. To our knowledge, this study presents the largest genomics resource currently available for T. dicoccoides, which, we believe, will encourage the exploitation of its genetic and genomic potential for wheat improvement to meet the increasing demand to feed the world

    A method for real-time identification and tracking of traveling ionospheric disturbances using ionosonde data: first results

    Get PDF
    Traveling Ionospheric Disturbances (TIDs) are wave-like propagating irregularities that alter the electron density environment and play an important role spreading radio signals propagating through the ionosphere. A method combining spectral analysis and cross-correlation is applied to time series of ionospheric characteristics (i.e., MUF(3000)F2 or foF2) using data of the networks of ionosondes in Europe and South Africa to estimate the period, amplitude, velocity and direction of propagation of TIDs. The method is verified using synthetic data and is validated through comparison of TID detection results made with independent observational techniques. The method provides near real time capability of detection and tracking of Large-Scale TIDs (LSTIDs), usually associated with auroral activity.Postprint (published version
    corecore