74 research outputs found
Correlation of velocity and susceptibility in patients with aneurysmal subarachnoid hemorrhage
In many cerebral grey matter structures including the neocortex, spreading
depolarization (SD) is the principal mechanism of the near-complete breakdown
of the transcellular ion gradients with abrupt water influx into neurons.
Accordingly, SDs are abundantly recorded in patients with traumatic brain
injury, spontaneous intracerebral hemorrhage, aneurysmal subarachnoid
hemorrhage (aSAH) and malignant hemispheric stroke using subdural electrode
strips. SD is observed as a large slow potential change, spreading in the
cortex at velocities between 2 and 9 mm/min. Velocity and SD susceptibility
typically correlate positively in various animal models. In patients monitored
in neurocritical care, the Co-Operative Studies on Brain Injury
Depolarizations (COSBID) recommends several variables to quantify SD
occurrence and susceptibility, although accurate measures of SD velocity have
not been possible. Therefore, we developed an algorithm to estimate SD
velocities based on reconstructing SD trajectories of the wave-front's
curvature center from magnetic resonance imaging scans and time-of-SD-arrival-
differences between subdural electrode pairs. We then correlated variables
indicating SD susceptibility with algorithm-estimated SD velocities in twelve
aSAH patients. Highly significant correlations supported the algorithm's
validity. The trajectory search failed significantly more often for SDs
recorded directly over emerging focal brain lesions suggesting in humans
similar to animals that the complexity of SD propagation paths increase in
tissue undergoing injury
Twin digital short period seismic Array Experiment at Stromboli Volcano
Two small arrays composed by short period (1 Hz) digital seismic
stations, with an aperture of approximately 400 meters, were set up at
Stromboli volcano (one at semaforo Labronzo, the other at Ginostra-
Timpone del Fuoco) with the purpose of the spatial location of the high
frequency source of the explosion quakes.
About 75 explosion-quakes were recorded at both arrays, and
constitute the available data base.
We have planned to apply the zero-lag cross-correlation technique to
the whole data set in order to obtain back-azimuth and apparent
slowness of the coherent seismic phases. A preliminary analysis for
both arrays show that the predominant back-azimuth for the first phase
is oriented in the direction of , but not strictly coincident to, the crater
area. Moreover some back-scattered arrivals are quite evident in the
seismogram.INGV - Osservatorio VesuvianoUnpublishedope
Findings of the WMT 2020 Biomedical Translation Shared Task: Basque, Italian and Russian as New Additional Languages
A seismic array on Mt. Vesuvius
In November 1997 a seismic antenna (array) of short period seismometers was
installed on the south-western flank of Mt. Vesuvius; aim of the experiment was to test the
use of non-conventional devices for the seismic monitoring of this volcano. In 7 months local
seismicity, regional earthquakes and samples of seismic noise were recorded by the array and
organised in a data base.
Local earthquakes and seismic noise have been analysed with array techniques to
investigate the spectral, kinematic and polarization properties of the wavefield. Preliminary
results show that the backazimuth of local earthquakes is oriented in the direction of the crater
area. For some events, the source location has been constrained using a simplified back
propagation in a 2-D velocity structure.
The noise wavefield is characterized by the predominance of a sustained low frequency
component (< 1Hz) whose source is located S-SE of the array. This low frequency signal has
been interpreted as associated to the sea-loading in the gulf of Naples.Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio VesuvianoPublished1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attiveope
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