Search results for "MAGNETIC FIELD"
showing 10 items of 1488 documents
Heavy metal exposure in patients suffering from electromagnetic hypersensitivity
2009
Abstract Background Risks from electromagnetic devices are of considerable concern. Electrohypersensitive (EHS) persons attribute a variety of rather unspecific symptoms to the exposure to electromagnetic fields. The pathophysiology of EHS is unknown and therapy remains a challenge. Objectives Heavy metal load has been discussed as a potential factor in the symptomatology of EHS patients. The main objective of the study was to test the hypothesis of a link between EHS and heavy metal exposure. Methods We measured lead, mercury and cadmium concentrations in the blood of 132 patients ( n = 42 males and n = 90 females) and 101 controls ( n = 34 males and n = 67 females). Results Our result…
Effects of an Earth-strength magnetic field on electrical activity of pineal cells
1980
Although magnetic fields can influence biological systems, including those of man and other vertebrates1–5, no central nervous structure has been identified that might be involved in their detection. From a theoretical point of view, the pineal organ might be such a structure for the following reasons: (1) It is involved in the regulation of circadian rhythms6 and is thus essential for migratory restlessness (‘Zugunruhe’)7. Orientation at that time can be altered by an artificial magnetic field (MF) with a direction differing by 90° from that of the Earth. Circadian rhythms can be inhibited from phase shifting by compensation of the Earth's MF and can be influenced by an artificial MF8. (2)…
No effects of mobile phone use on cortical auditory change-detection in children: an ERP study
2010
We investigated the effect of mobile phone use on the auditory sensory memory in children. Auditory event-related potentials (ERPs), P1, N2, mismatch negativity (MMN), and P3a, were recorded from 17 children, aged 11–12 years, in the recently developed multi-feature paradigm. This paradigm allows one to determine the neural change-detection profile consisting of several different types of acoustic changes. During the recording, an ordinary GSM (Global System for Mobile Communications) mobile phone emitting 902 MHz (pulsed at 217 Hz) electromagnetic field (EMF) was placed on the ear, over the left or right temporal area (SAR1g = 1.14 W/kg, SAR10g = 0.82 W/kg, peak value = 1.21 W/kg). The EMF…
1 Hz repetitive transcranial magnetic stimulation of the unaffected hemisphere ameliorates contralesional visuospatial neglect in humans
2002
The aim of the study was to investigate whether low-frequency repetitive transcranial magnetic stimulation (rTMS) over the unaffected hemisphere can ameliorate visuospatial neglect. We treated three right brain damaged patients with left neglect. 900 pulses (1 Hz frequency) were given over left posterior parietal cortex every other day for 2 weeks. Patients performed a computerized task requiring length judgement of prebisected lines, tachistoscopically presented for 150 ms. With respect to rTMS the task was given 15 days before, at the beginning, at the end and 15 days after. At these times patients performed also line bisection and clock drawing tasks. rTMS induced a significant improveme…
A case study of Primary Progressive Aphasia: improvement on verbs after rTMS treatment.
2006
This case-report shows that high frequency repetitive Transcranial Magnetic Stimulation (hf-rTMS), applied to the left prefrontal cortex, may improve the linguistic skills in Primary Progressive Aphasia (PPA). The patient's performance was evaluated on a battery of language production and memory span tasks, before and after two hf-rTMS treatments and one SHAM treatment. We observed a significant and lasting improvement of the patient's performance on verb production following the application of hf-rTMS versus Baseline and SHAM conditions. This finding suggests that hf-rTMS may directly strengthen the neural connections within an area of metabolic dysfunction and encourages the use of rTMS a…
Non-isothermal separation of ferrofluid particles through grids: Abnormal magnetic Soret effect
2013
Abstract Nanoparticle transport through thin non-isothermal ferrofluid layer between permeable walls is investigated. The transient mass flux is determined from measurements of particle concentration changes in two fluid chambers of different temperatures which are attached on both sides of the layer. Experiments are performed employing fluid samples of small ordinary magnetic Soret effect, which is detected by thermal grating technique. The separation measurements say that a magnetic field, aligned along a temperature gradient, causes a remarkable increase in the mass diffusion coefficient and a simultaneous decrease in particle thermodiffusion mobility. It is proposed that the observed ef…
Formation of magnetoconvection by photoabsorptive methods in ferrofluid layers
2013
Abstract A periodic concentration grating was induced in a layer of ferrofluid by photoabsorption and thermophoresis under the action of the applied uniform magnetic field. The application of the external field causes the appearance of an internal demagnetizing field within the layer and of magnetic forces due to the non-uniform distribution of concentration. The induced magnetic forces cause the appearance of parasitic microconvection within the layer. The experimental observations of the formation stage of the grating are interpreted to explain magnetoconvection, making use of numerical simulations.
Microstructure Design for Fast Lifetime Measurements of Magnetic Tunneling Junctions
2019
The estimation of the reliability of magnetic field sensors against failure is a critical point concerning their application for industrial purposes. Due to the physical stochastic nature of the failure events, this can only be done by means of a statistical approach which is extremely time consuming and prevents a continuous observation of the production. Here, we present a novel microstructure design for a parallel measurement of the lifetime characteristics of a sensor population. By making use of two alternative designs and the Weibull statistical distribution function, we are able to measure the lifetime characteristics of a CoFeB/MgO/CoFeB tunneling junction population. The main param…
Modulating the polarization of broadband terahertz pulses from a spintronic emitter at rates up to 10 kHz
2021
Reliable modulation of terahertz electromagnetic waveforms is important for many applications. Here, we rapidly modulate the direction of the electric field of linearly polarized terahertz electromagnetic pulses with 1–30 THz bandwidth by applying time-dependent magnetic fields to a spintronic terahertz emitter. Polarity modulation of the terahertz field with more than 99% contrast at a rate of 10 kHz is achieved using a harmonic magnetic field. By adding a static magnetic field, we modulate the direction of the terahertz field between angles of, for instance, −53° and 53° at kilohertz rates. We believe our approach makes spintronic terahertz emitters a promising source for low-noise modula…
Approach to quantitative spectroscopy of atomic vapor in optical nanocells
2019
We present a method for recovery of narrow homogeneous spectral features out of a broad inhomogeneous overlapped profile based on second-derivative processing of the absorption spectra of alkali metal atomic vapor nanocells. The method is shown to preserve the frequency positions and amplitudes of spectral transitions, thus being applicable for quantitative spectroscopy. The proposed technique was successfully applied and tested for measurements of hyperfine splitting and atomic transition probabilities, development of an atomic frequency reference, determination of isotopic abundance, study of atom-surface interaction, and determination of magnetic-field-induced modification of atomic tran…