We report the information that in the days of the radio anomaly presented in the paper Biagi et al. (2009) an interruption of the broadcasting from the transmitter (RMC, France) happened. It remains unclear if the action resulted in a complete power off of the system, or in a reduction in the radiated power, and if this has affected France only, or every direction. Should a complete power off have occurred, the proposed pre-seismic efocusing is inexistent. Our doubts on this action are reported.

In a previous study, an apparatus generating 1.8 GHz electromagnetic radiation for “in vivo” biomedical study was designed and implemented. The apparatus consisted of a reverberation chamber and it reproduced a habitat similar to the usual one for the laboratory animals. Plexiglas boxes with 300 cc physiological liquid were utilized as simple phantoms. For the measurements a small Electric Field Probe was used. The maximum SAR (Specific Absorption Rate) and average Power Efficiency Pe (SAR/input power) values obtained were quite low (“in vivo experiments”) and this was the drawback of the apparatus. In the present work, different modifications introduced in order to increase SAR and Power Efficiency are presented. In the new configuration, the dosimetry for the previous phantoms and for oil-in-gelatine phantoms was investigated and quite satisfactory SAR and Power Efficiency values were obtained, overcoming the previous drawback. In the first case the sensor was waterproofed, as in the previous study; in the other case a Plexiglas box with inside a tight shaped allocation for the measurement probe was realized. These measurement technologies could be applied to other media used for the phantoms.

We report the information that in the days of the radio anomaly presented in the paper Biagi et al. (2009) an interruption of the broadcasting from the transmitter (RMC, France) happened. It remains unclear if the action resulted in a complete power off of the system, or in a reduction in the radiated power, and if this has affected France only, or every direction. Should a complete power off have occurred, the proposed pre-seismic defocusing is inexistent. Our doubts on this action are reported.

In this paper we present results obtained from more than two years continuous very low frequency (VLF) measurements between a network of VLF transmitters and receivers. The focus is on VLF amplitude and phase variations in the Earth lithosphere-ionosphere cavity with the scientific objective to characterise long term trends possibly related to planetary waves and climatological factors. After considering the nominal diurnal and seasonal behaviour of the individual paths in the VLF waveguide, we distinguish between natural and artifical disturbances on different temporal and spatial scales. We conclude that it is too early to speak of a clear trend, but VLF investigations together with complementary measurements can be a useful tool in long term environmental and climatological studies on medium spatial scales

In this article we present results from very low frequency (VLF) observations of transient and intermittent phenomena in the Earth-ionosphere waveguide. The scientific objectives are remote localisation and characterisation of short time disturbances. The VLF amplitude and phase variations aid to physically investigate the atmospheric media from the Earth's surface up to the lower ionosphere ( 70-90 km, D- and E-region) which is part of propagation channels for satellite communications and navigational applications. We consider two common types of anomalies in the waveguide, these events are associated with (i) solar flares and (ii) geomagnetic storms. We conclude that with a continuous operating VLF receiver network a service for lower atmospheric channel monitoring / characterisation can be established.

We consider a broad area heterostructured semiconductor laser with an integrated saturable absorber in a monolithic configuration. We extend beyond the single-longitudinal mode approximation a model already used to predict transversely localized structures or cavity solitons (CSs) in a shorter device and we numerically demonstrate the existence of self-pulsing transverse localized structures. Like CSs, these structures can simultaneously coexist in different transverse locations.

The Romanian VLF / LF monitoring system consists in a radio receiver and the infrastructure that is necessary to record and transmit the collected data, and is part of the international initiative INFREP and was put into operation in December 2009 on the Black-Sea shore (Dobruja Seismologic Observatory - Dob-RO). Since then the system was developed by replacing the vertical antenna with a magnetic loop-type one, by installing a vertical electric field monitor and a weather station, and by designing special software for the transfer, storage and initial processing of data using the LabView software platform.

In the last years disturbances in VLF/LF radio signals related to seismic activity have been presented. The radio data were collected by receivers located on the ground or on satellites. The ground-based research implies systematic data collection by a network of receivers. Since 2000 the "Pacific VLF network", conducted by Japanese researchers, has been in operation. During 2008 a radio receiver was developed by the Italian factory Elettronika (Palo del Colle, Bari). The receiver is equipment working in VLF and LF bands. It can monitor 10 frequencies distributed in these bands and, for each of them, it saves the power level. At the beginning of 2009, five receivers were made for the realization of the "European VLF/LF Network"; two were planned for Italy and one for Greece, Turkey and Romania, respectively. In 2010 the network was enlarged to include a new receiver installed in Portugal. In this work, first the receiver and its setting up in the different places are described. Then, several disturbances in the radio signals related to the transmitters, receivers, meteorological/geomagnetic conditions are presented and described.

For several years researches about correlation between seismicity and disturbances in radio broadcasting are being carried out: in particular, the Japanese Pacific VLF radio network and the European VLF–LF radio network have been developed during the last years. The European network has been developed starting from two LF receivers located in central Italy in 1996. Up to now, 11 receivers of a new type, able to sample the VLF and LF intensity of ten radio signals, are being into operation in different European countries. The daily updating of data is effective and the data bank is located at the Department of Physics of the University of Bari (Italy) which is the central node of the network. In order to discover anomalies, the software able to carry out automatically a daily data analysis by the Wavelet spectra method has been planned and realized. At the moment, the software operates on four signals (two LF and two VLF) collected by one of the receiver located in Italy. If the anomaly is particularly strong a warning system gives an advise on the work station into operation in the central node of the Network. In any case, before assuming an anomaly as a seismic anomaly, geomagnetic and meteorological data must be checked as well as any possible instrumental malfunction. At present these controls are carried out only discontinuously by the researchers of the Bari Team.

The paper presents the Romanian VLF / LF monitoring system consisting in a radio receiver - made by Elettronika S.R.L. (Italy) and provided by the Bari University - and the infrastructure that is necessary to record and transmit the collected data. This system is a part of the international initiative INFREP. Through this initiative, originated in Italy, VLF / LF radio receivers are deployed in different locations in Europe. Each one is monitoring up to ten different transmissions of radio stations across the continent. Information on electromagnetic fields' intensities created by transmitters at each receiving site and gathered from this network are indicating the quality of the propagation along the paths between the receivers and transmitters. Studying the ionosphere influences on the electromagnetic waves' propagation along a certain path is a method to put into evidence possible modifications of ionosphere lower structure and composition as earthquakes' precursor. The VLF / LF receiver installed in Romania was put into operation in February 2009 and has proved its utility in the case of Abruzzo earthquake that occurred on 6th of April 2009 (M-w = 6.3). Since then, the receiver was relocated from Bucharest to the Black-Sea shore (Dobrogea Seismologic Observatory). Changing the receiving site produced unsatisfactory monitoring data, characterized by large fluctuations of the received signals' intensities. Trying to understand this behavior has led to the conclusion that the electric component of the electromagnetic field was possibly influenced by the local atmospheric conditions (as aerosols' concentrations could be). Starting from this observation we have run some tests which have indicated that a loop-type antenna is more appropriate than a vertical antenna, especially for highly electric-field polluted environments. Very good results were obtained with this new configuration, even in the site located at the Black-Sea shore. Future improvements of the receiver analog front-end are still possible in order to get better monitoring data by rejecting the off-band noise induced by the aerial high-voltage lines that are surrounding the site, so that for us to accomplish the best achievable surveillance in VLF / LF bands, related to seismo-electromagnetic phenomena.

In 2008, a radio receiver that works in very low frequency (VLF; 20-60 kHz) and LF (150-300 kHz) bands was developed by an Italian factory. The receiver can monitor 10 frequencies distributed in these bands, with the measurement for each of them of the electric field intensity. Since 2009, to date, six of these radio receivers have been installed throughout Europe to establish a 'European VLF/LF Network'. At present, two of these are into operation in Italy, and the remaining four are located in Greece, Turkey, Portugal and Romania. For the present study, the LF radio data collected over about two years were analysed. At first, the day-time data and the night-time data were separated for each radio signal. Taking into account that the LF signals are characterized by ground-wave and sky-wave propagation modes, the day-time data are related to the ground wave and the night-time data to the sky wave. In this framework, the effects of solar activity and storm activity were defined in the different trends. Then, the earthquakes with M ≥5.0 that occurred over the same period were selected, as those located in a 300-km radius around each receiver/transmitter and within the 5th Fresnel zone related to each transmitter-receiver path. Where possible, the wavelet analysis was applied on the time series of the radio signal intensity, and some anomalies related to previous earthquakes were revealed. Except for some doubt in one case, success appears to have been obtained in all of the cases related to the 300 km circles in for the ground waves and the sky waves. For the Fresnel cases, success in two cases and one failure were seen in analysing the sky waves. The failure occurred in August/September, and might be related to the disturbed conditions of the ionosphere in summer. © 2012 by the Istituto Nazionale di Geofisica e Vulcanologia. All rights reserved