Long-term <i>hm</i>F2 trends in the Eurasian longitudinal sector from the ground-based ionosonde observations

International audienceThe method earlier used for the foF2 long-term trends analysis is applied to reveal hmF2 long-term trends at 27 ionosonde stations in the European and Asian longitudinal sectors. Observed M(3000)F2 data for the last 3 solar cycles are used to derive hmF2 trends. The majority of the studied stations show significant hmF2 linear trends with a confidence level of at least 95% for the period after 1965, with most of these trends being positive. No systematic variation of the trend magnitude with latitude is revealed, but some longitudinal effect does take place. The proposed geomagnetic storm concept to explain hmF2 long-term trends proceeds from a natural origin of the trends rather than an artificial one related to the thermosphere cooling due to the greenhouse effect

A revised approach to the ?<i>o</i>F2 long-term trends analysis

International audienceA new approach to extract foF2 long-term trends, which are free to a great extent from solar and geomagnetic activity effects, has been proposed. These trends are insensitive to the phase (increasing/decreasing) of geomagnetic activity, with long-term variations being small and insignificant for such relatively short time periods. A small but significant residual foF2 trend, with the slope Kr = - 2.2 × 10-4 per year, was obtained over a 55-year period (the longest avail-able) of observations at Slough. Such small trends have no practical importance. On the other hand, negative (although insignificant) residual trends obtained at 10 ionosonde stations for shorter periods (31 years) may be considered as a manifestation of a very long-term geomagnetic activity increase which did take place during the 20th century. All of the revealed foF2 long-term variations (trends) are shown to have a natural origin related to long-term variations in solar and geomagnetic activity. There is no indication of any manmade foF2 trends. Key words. Ionosphere (ionosphere-atmosphere interactions, ionospheric disturbances

Quasi elastic cross sections for the Bi-209(e, e \u27 p)Pb-208 reaction: Jefferson Lab experiment E06007

Quasi elastic cross sections were measured for the first time for both negative and positive missing momenta for the Bi-209(e, e\u27p)Pb-208 reaction leading to the ground state and hole states of Pb-208. Experimental cross sections obtained between -0.3 GeV/c to 0.3 GeV/c agree with theoretical calculations using RDWIA techniques both in shape and magnitude for the ground state. The data for the ground state production of Pb-208 are consistent with a theoretical model assuming a single proton(1.06 +/- 0.10) in the 1h9/2 orbit in Bi-209

Worst cases for a one-hop high frequency link

The characterisation of a HF channel by means of monthly electron density profiles can be complemented with a detailed study of radio propagation «worst cases» on situations with extremes conditions of radiopropagation for a given period. These «worst cases» correspond to conditions that can be identified by means of cumulative distributions of the key parameter f0F2. This paper analyses the main parameters of the HF channel: time delay, apogee, elevation angle and transmission frequency with mean and extreme conditions. The method used to characterise the ionospheric channel is based on ray-tracing techniques.National Institute of Aerospace Technology (INTA)Dr. Moorhead of Neptune Radar Ltd.Gloucester U.

Worst cases for an one-hop high frequency link

The characterisation of a HF channel by means of monthly electron density profiles can be complemented with a detailed study of radio propagation «worst cases» on situations with extremes conditions of radiopropagation for a given period. These «worst cases» correspond to conditions that can be identified by means of cumulative distributions of the key parameter f0F2. In this paper, the main parameters of the HF channel: time delay, apogee, elevation angle and transmission frequency with mean and extreme conditions are analysed. The method used to characterise the ionospheric channel is based on ray-tracing techniques

The 4q25 variant rs13143308T links risk of atrial fibrillation to defective calcium homoeostasis

Aims: Single nucleotide polymorphisms on chromosome 4q25 have been associated with risk of atrial fibrillation (AF) but the exiguous knowledge of the mechanistic links between these risk variants and underlying electrophysiological alterations hampers their clinical utility. Here, we tested the hypothesis that 4q25 risk variants cause alterations in the intracellular calcium homoeostasis that predispose to spontaneous electrical activity. Methods and results: Western blotting, confocal calcium imaging, and patch-clamp techniques were used to identify mechanisms linking the 4q25 risk variants rs2200733T and rs13143308T to defects in the calcium homoeostasis in human atrial myocytes. Our findings revealed that the rs13143308T variant was more frequent in patients with AF and that myocytes from carriers of this variant had a significantly higher density of calcium sparks (14.1¿±¿4.5 vs. 3.1¿±¿1.3 events/min, P¿=¿0.02), frequency of transient inward currents (ITI) (1.33¿±¿0.24 vs. 0.26¿±¿0.09 events/min, P¿<¿0.001) and incidence of spontaneous membrane depolarizations (1.22¿±¿0.26 vs. 0.56¿±¿0.17 events/min, P¿=¿0.001) than myocytes from patients with the normal rs13143308G variant. These alterations were linked to higher sarcoplasmic reticulum calcium loading (10.2¿±¿1.4 vs. 7.3¿±¿0.5¿amol/pF, P¿=¿0.01), SERCA2 expression (1.37¿±¿0.13 fold, P¿=¿0.03), and RyR2 phosphorylation at ser2808 (0.67¿±¿0.08 vs. 0.47¿±¿0.03, P¿=¿0.01) but not at ser2814 (0.28¿±¿0.14 vs. 0.31¿±¿0.14, P¿=¿0.61) in patients carrying the rs13143308T risk variant. Furthermore, the presence of a risk variant or AF independently increased the ITI frequency and the increase in the ITI frequency observed in carriers of the risk variants was exacerbated in those with AF. By contrast, the presence of a risk variant did not affect the amplitude or properties of the L-type calcium current in patients with or without AF. Conclusions: Here, we identify the 4q25 variant rs13143308T as a genetic risk marker for AF, specifically associated with excessive calcium release and spontaneous electrical activity linked to increased SERCA2 expression and RyR2 phosphorylation.Peer ReviewedPostprint (author's final draft

Indicadores de salud perinatal. Diferencias de la información registrada por el INE y la de los hospitales que atienden los nacimientos

La búsqueda de medidas objetivas del estado de salud de la población es una tradición en salud pública que se realiza desde hace dos siglos. Inicialmente, la descripción y análisis del estado de salud se basaba en medidas de mortalidad y supervivencia. Con el paso del tiempo se reconoció la necesidad de considerar también otras dimensiones del estado de salud, en parte para el control de enfermedades y en parte por tener una visión más amplia del concepto de salud y de sus determinantes poblacionales..

MAPPING OF CODA ATTENUATION AT THE EXTEND OF THE NATIONAL SEISMOLOGICAL NETWORK OF GREECE

Coda decay rates of 538 vertical components corresponding to local earthquakes which occurred in Greece during the period 1998 to 1999 were used to deduce the coda quality factor (Qc) characteristics in the Hellenic area. The seismograms have been selected from a broader sample of 776 records obtained at 8 stations of the National Seismographic Network operated by the Institute of Geodynamics of the National Observatory of Athens. Earthquake magnitudes range from 2.5 to 4.0; epicentral distances and depths are smaller than 100 km and 40 km, respectively. Using the Single Back Scattering model, the dependence of Qc on frequencies between 1 and 10 Hz has been investigated at each station and the usual Qc =Qo f relationships have been deduced. The spatial distribution of Qo has been drawn using waves that sample approximately equivalent ellipsoidal volumes with semiminor axis up to 100 km. The corresponding map shows a decreasing trend in SN direction