[en] Biological systems interactions with Elf magnetic fields are presented: review of studies, standards and mitigation; also, measurements in occupational and residential environments in Medellin

[en] A tutorial introduction to transient electromagnetics, focusing on direct time-domain techniques, is presented. Physical, mathematical, numerical, and experimental aspects of time-domain methods, with emphasis on wire objects excited as antennas or scatters are examined. Numerous computed examples illustrate the characteristics of direct time-domain procedures, especially where they may offer advantages over procedures in the more familiar frequency domain. These advantages include greater solution efficiency for many types of problems, the ability to handle nonlinearities, improved physical insight and interpretability, availability of wide-band information from a single calculation, and the possibility of isolating interactions among various parts of an object using time-range gating

[en] The interplay between quantization and topology is investigated in the frame of a topological model of electromagnetism proposed by the author. In that model, the energy of electromagnetic radiation in a cubic cavity is E=(d/4)ℎω where d is a topological integer index equal to the degree of a map between two orbifolds

[en] Complete text of publication follows. On land more and more reliable observations show unambiguous signals before volcanic eruptions. In electromagnetism, many land observations outline resistivity changes, long time evolution of the magnetic field, transient magnetic and electric signals before volcanic outbursts. But, only some tens of volcanoes in the world are monitored by complex geophysical equipments, while a hundreds of volcanoes remain without any adequate observations and monitoring systems. Multi-platform satellites could partly contribute to the mitigation of volcanic risks and trap some of the pre-eruptive signals, even if the data sampling between consecutive orbits over a volcano is of some hours or more. Since June 2004, the micro-satellite Demeter, launched by CNES (French National Space Agency) records over the Earth several parameters (electrons (ISL) and plasma (IAP) temperature and density), along with the magnetic and electric fields. The objective of this study is to analyze Demeter data around the time of volcanic eruptions over several years. Therefore, a database was built as follow: (1) the period under study starts in September 2004 when DEMETER is fully in operation and ends in December 2007, (2) only volcanoes located between latitudes -55 deg and +55 degN are taken into account, (3) volcanoes characterized by a Volcanic Explosivity Index VEI≥1 are considered, independently of their location and eruptive behaviour, (4) the database is shaped by observations from downwards (north to south) and upwards (south to north) orbits, from 30 days before the eruption to 15 days after, and (4) for any orbit data are analysed if the maximum distance between the footprint of the satellite and the volcano under study is 500 km for VEI < 3 and 900 km for VEI≥3. 74 volcanic eruptions have respected the above criteria, which represents the analysis of about 6600 orbits. They concern 50 volcanoes. 30 eruptions are accompanied by anomalies during the time window starting 30 days before the eruption and ending 15 days after. It means that 41% of the considered eruptions are accompanied by anomalies recorded by Demeter satellite. In total, 48 anomalies are found and classified in three types. 81% of the anomalies are observed before the eruptions. For most of the eruptions only one type of anomaly is recorded, and anomalies seem to appear independently of the characteristics of the volcano (i.e. dynamism, VEI index, location, regional setting). It is still rather difficult to find any correlation between the characteristics of the anomalies (i.e. amplitude, duration, and frequency content) and the strength of the future activity. Nevertheless, one can noticed that the number of anomalies is at most 3 for 4 volcanoes, the VEI of which is ≥ 2 (Lascar, VEI=3; Lopevi, VEI=2; Kartala, VEI=2; Fernandina, VEI=2).

[en] The discovery of electromagnetic induction in the early part of the 19th century is one of the greatest scientific achievements of all time, and it has had tremendous technological consequences. The credit for this discovery rightfully goes to the great English experimental physicist Michael Faraday. However, the American physicist Joseph Henry made some observations comparable to Faraday’s at nearly the same time, and for that reason, Faraday and Henry are often considered to be co-discoverers of some aspects of electromagnetic induction. We examine Henry’s early research on electromagnetism, starting from his efforts to improve the electromagnet, which led directly to his investigations of induction. We describe his earliest experiments on both mutual and self-induction, and pay particular attention to the relationship of Henry’s research to that of Faraday. The approach is one in which the experiments are described and then analysed using modern theory and terminology. (paper)

No abstract available

[en] A phase transition has been studied in a random system of two-level atoms interacting with an electromagnetic field. It is shown that superradiation can arise when there is short-range order in a spin-subsystem. The existence of long-range order is irrelevant for this phase transition

[en] A fundamental theorem on particle acceleration is derived from the reciprocity principle of electromagnetism and a rigorous proof of the theorem is presented. The theorem establishes a relation between acceleration and radiation, which is particularly useful for insightful understanding of and practical calculation about the first order acceleration in which energy gain of the accelerated particle is linearly proportional to the accelerating field

[en] Electromagnetic induction is the most common technique used for geophysical survey of underground utilities. Hence, pipe and cable locator (PCL) is a device that used to detect the magnetic field that are performed. This project focussed on detect of passive signal and active signal. The application of pipe and cable locator in construction study is briefly reviewed. The various data through previous references used to discuss and analyse the capability of pipe and cable locator for further improvement in construction projects, which should be considered in future vision of standards. (author)

[en] The reflection, transmission, and absorption coefficients are derived for long-wavelength electromagnetic radiation propagating through a medium that exhibits a Gaussian conductivity. It is shown that, under certain circumstances, this applies to the ionosphere. The effects of different peak conductivities and Gaussian widths are examined, and a useful form for calculating transmission and reflection coefficients is presented. copyright 1997 American Institute of Physics