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Bioelectric and Biomagnetic Signal Analysis
Published in Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam, Introduction to Computational Health Informatics, 2019
Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam
MEG sensing technology includes magnetometers – a pickup coil to measure magnetism. The coils are put on the scalp. The magnetic wave has two components: vertical going away from the source of electrical activity and the scalp position and parallel to the scalp. The vertical component of the magnetic field generates an electric current in the coil, which is magnified using superconductors cooled by liquid helium. Since the magnetic activity is very weak, noise-filtering and boosting the signal are done in a magnetically shielded room. Signal-to-noise ratio is very important. The magnetic activity is sampled at 5,000 Hz. Magnetic activity is expressed in femto-Tesla (10−15 Tesla).
The Impact of Technology on Mental Health
Published in Bahman Zohuri, Patrick J. McDaniel, Electrical Brain Stimulation for the Treatment of Neurological Disorders, 2019
Bahman Zohuri, Patrick J. McDaniel
The MEG technique that is a functional way of mapping brain activity by recording magnetic fields that are driven by naturally occurring electrical currents in the brain. It uses very sensitive magnetometers as illustrated in Figure 4.23.
Brain stimulation: new directions
Published in Alan Weiss, The Electroconvulsive Therapy Workbook, 2018
Magnetoencephalography (MEG) is fast, non- invasive, patient-friendly functional neuroimaging technique for mapping brain activity. It is reputed to be the most modern imaging tool available to radiologists (Braeutigam, 2013). Magnetic fields that are produced naturally by electrical currents within the brain are detected by very sensitive magnetometers. There are two types: supercon-ducting quantum interference devices (SQUIDs), which are the most common, and spin exchange relation-free (SERF) magnetometers (Braeutigam, 2013).
Reliability and validity of smartphone applications to measure the spinal range of motion: A systematic review
Published in Expert Review of Medical Devices, 2021
Shibili Nuhmani, Moazzam Hussain Khan, Shaji J Kachanathu, Mohd Arshad Bari, Turki S Abualait, Qassim I Muaidi
Comparatively lower reliability and validity indices of smartphone applications for rotation ROM may be due to several factors. Static errors of smartphone sensors were three times higher in the transverse plane than in other cardinal planes [33]. Other factors include differences in smartphone sensors (magnetometers versus gravity-dependent gyroscopes) for ROM measurements in different planes. Magnetometers are preferable for the measurement of axial rotations in anti-gravity positions (e.g. sitting or standing). When compared to gyroscopes, magnetometers are more sensitive to signal distortion from environmental magnetic fields, which may reduce validity and reliability. The studies [27,30], which showed inadequate reliability and validity of smartphone applications, used magnetometer components for all measurements, as measurements were taken in the anti-gravity position. Similarly, Pourahmadi MR (25] also measured axial rotation in the supine position, using the gyroscope component of a smartphone sensor. This approach justified better reliability and validity of cervical rotation movements in their study compared with other studies [24,25]. A third influencing factor may have been the misalignment of the axis during measurement. This issue is more common in rotatory movements of the spine than other spinal movements, as there is a higher chance of secondary movements during rotation [34].
Assessment of cognitive instrumental activities of daily living: a systematic review
Published in Disability and Rehabilitation, 2021
Dulce Romero-Ayuso, Álvaro Castillero-Perea, Pascual González, Elena Navarro, José Pascual Molina-Massó, M. Jesús Funes, Patrocinio Ariza-Vega, Abel Toledano-González, José Matías Triviño-Juárez
In addition to virtual tasks, there were other methodologies used to evaluate ADLs by means of serious games platforms [70], combining game playing with a serious purpose such as that of assessing functional independence in older people through five ADL tasks in a family environment using the Smart Aging game [71]. Other types of assessments conducted with new technologies involve the use of sensors that collect data about participants’ gestures, movements, location, interactions and actions [72]. For example, accelerometers are sensors that have been used to monitor the activity of getting dressed; magnetometers measure the strength of the magnetic field in three dimensions, provide guidance to users and detect and locate metallic objects within their detection radius. The location of the sensor (and of the person carrying it) can be determined based on its proximity to the objects detected. Finally, emerging studies are exploring the relationship between eye movement and changes in ocular fixation as predictors of cognitive and functional impairment [73].
Attention Focus Does Not Influence Performance of Sit-to-Stand in Young and Older Adults
Published in Journal of Motor Behavior, 2021
Valéria A Pinto, Alice B Campolina, Alysson F Mazoni, Daniela J S Mattos, Daniela V Vaz
The angle (radians) of the cup with respect to the global vertical was calculated. The magnetometer was used to mark a three-dimensional vector whose variation from an initial position is taken as an inclination (the cup and smartphone were vertical while resting on a table before beginning and after the end of the movement). The inclination was then projected to the vertical axis to calculate the smartphone angle (parallel to the cup). Magnetometer signals are noisy so data from the other sensors are used to improve it. The magnetometer signal is interpolated to optimally reduce the error of its derivatives compared to the gyroscope and accelerometer. The resulting signal is an estimate of the cup angle. The average and standard deviation of the cup angle over time, for the duration of a sit-to-stand and stand-to-sit, were obtained for each trial.