Upper body balance control strategy during continuous 3D postural perturbation in young adults

We explored how changes in vision and perturbation frequency impacted upright postural control in healthy adults exposed to continuous multiaxial support-surface perturbation. Ten subjects were asked to maintain equilibrium in standing stance with eyes open (EO) and eyes closed (EC) during sinusoidal 3D rotations at 0.25 (L) and 0.50 Hz (H). We measured upper-body kinematics – head, trunk, and pelvis – and analyzed differences in horizontal displacements and roll, pitch, and yaw sways. The presence of vision significantly decreased upper-body displacements in the horizontal plane, especially at the head level, while in EC the head was the most unstable segment. H trials produced a greater segment stabilization compared to L ones in EO and EC. Analysis of sways showed that in EO participants stabilized their posture by reducing the variability of trunk angles; in H trials a sway decrease for the examined segments was observed in the yaw plane and, for the pelvis only, in the pitch plane. Our results suggest that, during continuous multiaxial perturbations, visual information induced: (i) in L condition, a continuous reconfiguration of multi-body-segments orientation to follow the perturbation; (ii) in H condition, a compensation for the ongoing perturbation. These findings were not confirmed in EC where the same strategy – that is, the use of the pelvis as a reference frame for the body balance was adopted both in L and H

reach to grasp interjoint coordination for moving objects in children with hemiplegia

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Shear wave splitting changes associated with the 2001 volcanic eruption on Mt. Etna

The time delays and polarizations of shear wave splitting above small earthquakes show variations before the 2001 July 17–August 9 2001 flank eruption on Mt Etna, Sicily. Normalized time delays, measured by singular value decomposition, show a systematic increase starting several days before the onset of the eruption. On several occasions before the eruption, the polarization directions of the shear waves at Station MNT, closest to the eruption, show 90◦- flips where the faster and slower split shear waves exchange polarizations. The last 90◦-flip being 5 days before the onset of the eruption. The time delays also exhibit a sudden decrease shortly before the start of the eruption suggesting the possible occurrence of a ‘relaxation’ phenomena, due to crack coalescence. This behaviour has many similarities to that observed before a number of earthquakes elsewhere

Excitonic mobility edge and ultra-short photoluminescence decay time in n-type GaAsN

We use time-resolved photoluminescence (PL) spectroscopy to study the recombination dynamics in Si-doped GaAsN semiconductor alloys with a nitrogen content up to 0.2%. The PL decay is predominantly monoexponential and exhibits a strong energy dispersion. We find ultra-short decay times on the high-energy side and long decay times on the low-energy side of the photoluminescence spectrum. This asymmetry can be explained by the existence of an additional non-radiative energy transfer channel and is consistent with previous studies on intrinsic GaAsN epilayers. However, the determined maximum decay times of GaAsN:Si are significantly reduced in comparison to undoped GaAsN. The determined excitonic mobility edge energy constantly decreases with an increase in the N content, in agreement with the two-level band anticrossing model

Shear wave splitting time variation by stress-induced magma uprising at Mount Etna volcano

Shear wave splitting exhibits clear time variations before the July 17th – August 9th, 2001 flanK eruption at Mount Etna. The normalized time delays, Tn, detected through an orthogonal transformation of singular value decomposition, exhibit a clearincrease starting 20 days before the occurrence of the eruption (July 17th); the qS1 polarization direction, obtained using a 3D covariance matrix decomposition, shows a 90°-flip several times during the analyzed period: the last flip 5 days before the occurrence of the eruption. Both splitting parameters also exhibit a relaxation phase shortly before the starting of the eruption. Our observations seem in agreement with Anisotropic Poro Elasticity (APE) modelling, suggesting a tool for the temporal monitoring of the build up of the stress leading to the occurrence of the 2001 eruption at Mt. Etna

In-stent restenosis of superficial femoral artery: use all arrows in the quiver.

In-stent restenosis (ISR) is a common superficial femoral artery (SFA) stenting complication, occurring in more than one third of patients within 2-3 years after the index procedure. Moreover, there is no standard treatment for ISR, and although many options are available, there is still limited data regarding its optimal management. We report a paradigmatic case report of a patient complaining of symptomatic peripheral arterial disease, underwent multiple endovascular revascularizations for recurrent femoro-popliteal ISR. A step-by-step approach was followed. At the time of the first presentation, the ISR was treated by drug-eluting balloon (DEB) angioplasty. The repeated ISR was treated by laser debulking, achieving a good angiographic result. Finally, after the third repeated restenosis, a combined approach with laser debulking and DEB angioplasty guaranteed a good acute angiographic result. Long-term duplex-scan follow-up demonstrated the good patency of the femoro-popliteal target lesion

Controlling high-frequency collective electron dynamics via single-particle complexity

We demonstrate, through experiment and theory, enhanced high-frequency current oscillations due to magnetically-induced conduction resonances in superlattices. Strong increase in the ac power originates from complex single-electron dynamics, characterized by abrupt resonant transitions between unbound and localized trajectories, which trigger and shape propagating charge domains. Our data demonstrate that external fields can tune the collective behavior of quantum particles by imprinting configurable patterns in the single-particle classical phase space.Comment: 5 pages, 4 figure

Electron spin coherence near room temperature in magnetic quantum dots

We report on an example of confined magnetic ions with long spin coherence near room temperature. This was achieved by confining single Mn2+ spins in colloidal semiconductor quantum dots (QDs) and by dispersing the QDs in a proton-spin free matrix. The controlled suppression of Mn–Mn interactions and minimization of Mn–nuclear spin dipolar interactions result in unprecedentedly long phase memory (TM ~ 8 μs) and spin–lattice relaxation (T1 ~ 10 ms) time constants for Mn2+ ions at T = 4.5 K, and in electron spin coherence observable near room temperature (TM ~ 1 μs)

Acquisition and preliminary analysis of multi-channel seismic reflection data, acquired during the oceanographic cruises of the TOMO-ETNA experiment

The TOMO-ETNA experiment was performed in the framework of the FP7 “MED-SUV” (MEDiterranean SUpersite Volcanoes) in order to gain a detailed geological and structural model of the continental and oceanic crust concerning Etna and Aeolian Islands volcanoes (Sicily, Italy), by means of active and passive seismic exploration methodologies. Among all data collected, some 1410 km of marine multi-channel seismic (MCS) reflection profiles were acquired in the Ionian and Tyrrhenian Seas during two of the three oceanographic cruises of the TOMO-ETNA experiment, in July and November 2014, with the aim of shading light to deep, intermediate and shallow stratigraphy and crustal structure of the two above mentioned areas. The MCS sections, targeted to deep exploration, were acquired during the oceanographic cruise on board of the R/V “Sarmiento de Gamboa”, using an active seismic source of 16 air-guns, for a total volume of 4340 cu. in., and a 3000 m long, 240-channels digital streamer as receiving system. High-resolution seismic profiles were instead collected through the R/V “Aegaeo”, using two smaller air-guns (overall 270 cu. in. volume) and a 96 channels, 300 m long digital streamer. This paper provides a detailed description of the acquisition parameters and main processing steps adopted for the MCS data. Some processed lines are shown and preliminarily interpreted, to highlight the overall good quality and the high potential of the MCS sections collected during the TOMO-ETNA experiment. © 2016 by the Istituto Nazionale di Geofisica e Vulcanologia. All rights reserved

Toward Forecasting Volcanic Eruptions using Seismic Noise

During inter-eruption periods, magma pressurization yields subtle changes of the elastic properties of volcanic edifices. We use the reproducibility properties of the ambient seismic noise recorded on the Piton de la Fournaise volcano to measure relative seismic velocity variations of less than 0.1 % with a temporal resolution of one day. Our results show that five studied volcanic eruptions were preceded by clearly detectable seismic velocity decreases within the zone of magma injection. These precursors reflect the edifice dilatation induced by magma pressurization and can be useful indicators to improve the forecasting of volcanic eruptions.Comment: Supplementary information: http://www-lgit.obs.ujf-grenoble.fr/~fbrengui/brenguier_SI.pdf Supplementary video: http://www-lgit.obs.ujf-grenoble.fr/~fbrengui/brenguierMovieVolcano.av