Search results for "MAGNETIC FIELD"
showing 10 items of 1488 documents
Experimental and Modeling Analyses of Human Motion Across the Static Magnetic Field of an MRI Scanner
2021
It is established that human movements in the vicinity of a permanent static magnetic field, such as those in magnetic resonance imaging (MRI) scanners induce electric fields in the human body; this raises potential severe risks of health to radiographers and cleaners exposed routinely to these fields in MRI rooms. The relevant directives and parameters, however, are based on theoretical models, and accurate studies on the simulation of the effects based on human movement data obtained in real conditions are still lacking. Two radiographers and one cleaner, familiar with MRI room activities and these directives, were gait analyzed during the execution of routine job motor tasks at different…
Study of a Novel High Permeability Ferrite Sheet Intended for Near Field Communication Systems
2019
The reduction of embedded portable devices involves a magnetic field interference problem when it integrates Near Field Communication (NFC) due to the presence of conductive surfaces such as ground planes, batteries or metallic enclosures. This contribution is focused on analyzing the ability of an innovative magnetic shielding based on flexible sintered ferrite sheets (FSFS) with the aim of improving the performance of that kind of systems. Thereby, a NFC emitter antenna is characterized when it is close to a conductive surface through an electromagnetic (EM) scanner. The EM scanner composed by a matrix of near field probes that make it possible to determine the effectiveness of the FSFS. …
A sampling method for detecting buried objects using electromagnetic scattering
2005
We consider a simple (but fully three-dimensional) mathematical model for the electromagnetic exploration of buried, perfect electrically conducting objects within the soil underground. Moving an electric device parallel to the ground at constant height in order to generate a magnetic field, we measure the induced magnetic field within the device, and factor the underlying mathematics into a product of three operations which correspond to the primary excitation, some kind of reflection on the surface of the buried object(s) and the corresponding secondary excitation, respectively. Using this factorization we are able to give a justification of the so-called sampling method from inverse scat…
Laboratory disruption of scaled astrophysical outflows by a misaligned magnetic field
2021
The shaping of astrophysical outflows into bright, dense, and collimated jets due to magnetic pressure is here investigated using laboratory experiments. Here we look at the impact on jet collimation of a misalignment between the outflow, as it stems from the source, and the magnetic field. For small misalignments, a magnetic nozzle forms and redirects the outflow in a collimated jet. For growing misalignments, this nozzle becomes increasingly asymmetric, disrupting jet formation. Our results thus suggest outflow/magnetic field misalignment to be a plausible key process regulating jet collimation in a variety of objects from our Sun’s outflows to extragalatic jets. Furthermore, they provide…
Interference of left and right cerebellar rTMS with procedural learning.
2004
Abstract Increasing evidence suggests cerebellar involvement in procedural learning. To further analyze its role and to assess whether it has a lateralized influence, in the present study we used a repetitive transcranial magnetic stimulation interference approach in a group of normal subjects performing a serial reaction time task. We studied 36 normal volunteers: 13 subjects underwent repetitive transcranial magnetic stimulation on the left cerebellum and performed the task with the right (6 subjects) or left (7 subjects) hand; 10 subjects underwent repetitive transcranial magnetic stimulation on the right cerebellum and performed the task with the hand ipsilateral (5 subjects) or contral…
The role of the dorsolateral prefrontal cortex in implicit procedural learning.
1996
We studied the role of the dorsolateral prefrontal cortex in procedural learning. Normal subjects completed several blocks of a serial reaction time task using only one hand without or with concurrent non-invasive repetitive transcranial magnetic stimulation. To disrupt their function transiently, stimulation was applied at low intensity over the supplementary motor area or over the dorsolateral prefrontal cortex contralateral or ipsilateral to the hand used for the test. Stimulation to the contralateral dorsolateral prefrontal cortex markedly impaired procedural implicit learning, as documented by the lack of significant change in response times during the task. Stimulation over the other …
Influenza di campi magnetici a bassa frequenza (ELF-MFS) sull'accrescimento in vitro di callo di Salvia officinalis "Maxima"
2012
La presente ricerca ha avuto lo scopo di valutare la risposta di una coltura cellulare di Salvia officinalis sottoposta ad un flusso magnetico della densità di 50 milliTesla per la durata di 0, 1, 2, 3, 4, o 5 minuti. Il callo è stato allevato su substrato agarizzato di Murashige e Skoog addizionato con 0,5 mg L-1 2,4-D e 0,5 mg L-1 chinetina. Dopo il trattamento le colture sono state poste in camera di crescita ad una temperatura di 24˚C ed in presenza di 16 ore di luce. Il tasso di crescita relativo, parametro indicativo del ritmo di accrescimento della coltura di cellule indifferenziate, è risultato crescente all’aumentare del periodo di esposizione al campo magnetico, raggiungendo dopo …
Orbital Evolution of an Accreting Millisecond Pulsar: Witnessing the Banquet of a Hidden Black Widow?
2007
We have performed a timing analysis of all the four X-ray outbursts from the accreting millisecond pulsar SAX J1808.4-3658 observed so far by the PCA on board RXTE. For each of the outbursts we derived the best-fit value of the time of ascending node passage. We find that these times follow a parabolic trend, which gives an orbital period derivative $\dot P_{\rm orb} = (3.40 \pm 0.18) \times 10^{-12}$ s/s, and a refined estimate of the orbital period, $P_{\rm orb} = 7249.156499 \pm 1.8 \times 10^{-5}$ s (reference epoch $T_0 = 50914.8099$ MJD). This derivative is positive, suggesting a degenerate or fully convective companion star, but is more than one order of magnitude higher than what is…
Magnetic activity and the solar corona: first results from the Hinode satellite
2007
The structure, dynamics and evolution of the solar corona are governed by the magnetic field. In spite of significant progresses in our insight of the physics of the so- lar corona, several problems are still under debate, e.g. the role of impulsive events and waves in coronal heating, and the origin of eruptions, flares and CMEs. The Hinode mis- sion has started on 22 september 2006 and aims at giving new answers to these questions. The satellite contains three main instruments, two high resolution telescopes, one in the optical and one in the X-ray band, and an EUV imaging spectrometer. On the Italian side, INAF/Osservatorio Astronomico di Palermo has contributed with the ground-calibrati…
Testing the Ability of Field Extrapolation Models to Predict the X-ray Emission Properties of Pre-Main Sequence Stars
2010
By extrapolating from observationally derived magnetic surface maps, obtained through Zeeman-Doppler imaging, models of stellar magnetospheres can be constructed. By assuming that the plasma trapped along the closed field lines is in hydrostatic equilibrium, coronal X-ray emission properties, such as the global X-ray emission measure and the amount of rotational modulation of X-ray emission, can be predicted. For pre-main sequence magnetospheres the analysis can be extended to incorporate accretion flows, and predict the amount of softer X-ray emission from accretion spots that would be observed. I will detail the preliminary results of an ambitious multi-wavelength, multi-observing site, a…