1,306 research outputs found

    The weight of time: gravitational force enhances discrimination of visual motion duration

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    In contrast with the anisotropies in spatial and motion vision, anisotropies in the perception of motion duration have not been investigated to our knowledge. Here, we addressed this issue by asking observers to judge the duration of motion of a target accelerating over a fixed length path in one of different directions. Observers watched either a pictorial or a quasi-blank scene, while being upright or tilted by 45° relative to the monitor and Earth's gravity. Finally, observers were upright and we tilted the scene by 45°. We found systematic anisotropies in the precision of the responses, the performance being better for downward motion than for upward motion relative to the scene both when the observer and the scene were upright and when either the observer or the scene were tilted by 45°, although tilting decreased the size of the effect. We argue that implicit knowledge about gravity force is incorporated in the neural mechanisms computing elapsed time. Furthermore, the results suggest that the effects of a virtual gravity can be represented with respect to a vertical direction concordant with the visual scene orientation and discordant with the direction of Earth's gravity

    Local seismic response studies in the north-western portion of the August 24th, 2016 Mw 6.0 earthquake affected area. The case of Visso village (Central Apennines).

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    In this work, we investigate the possible causes of the differential damaging observed in Visso village (Central Apennines, about 28 km north from the August 24th, 2016 Mw 6.0 earthquake epicenter). Following insights from the available geological cartography at 1:10.000 scale, a preliminary geophysical survey has been performed in the damaged area in order to constrain geometries and extent of the subsoil lithotypes. Then, these results have been used to retrieve a Vs profile close to the most heavily damaged buildings. This latter has been used as input for a numerical analysis aimed at deriving the motion at the ground level in the study area. In particular, a linear equivalent simulation has been performed by means of EERA code and the waveform has been obtained convolving the time history recorded during the August 24th, 2016 mainshock at Spoleto Monteluco (SPM) site. Our preliminary results indicate a possible correlation of damaging to the thickness and shape of the geological units. Nevertheless, further analyses are necessary to highlight any 2D basin and / non- linear soil behaviour effects in order to compare them to the intrinsic buildings vulnerability, according to the EMS98 guidelines

    Optimization of Plasmas for Recombination-Pumped Short-Wavelength Lasers

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    We report on experiments investigating the optimization of laser-ablated plasmas which are used to produce recombination-pumped, short-wavelength lasers. We evaluate the density of electrons and neutral atoms in laser ablated lithium and carbon plasmas as a function of time and distance away from the ablated target surface. We use an interferometric technique which can reveal information about the temperature of the plasma electrons. We find that the cold electrons which result in gain in recombination-pumped lithium lasers on the Lyman-α transition are produced by the high-intensity pump pulse rather than the lower intensity ablating pulse

    Evaluation of site effects by means of 3D numerical modeling of the Palatine Hill, Roman Forum, and Coliseum archaeological area

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    In this study we perform 3D nonlinear analyses of seismic site response of the Central Archaeological Area of Rome, which includes the Palatine Hill, Roman Forum, Circus Maximus, and Coliseum. The geological bedrock of the study area is constituted by a Pliocene marine sandy-clayey unit (MonteVaticano Formation, MVA). At top of this unit a continental Quaternary succession is superimposed. Previous studies available for this area (Pagliaroli et al. 2014a; Mancini et al. 2014; Moscatelli et al. 2014) enabled to define a detailed three-dimensional reconstruction of the subsoil conditions, characterized by complex surficial and buried morphology, lateral heterogeneities and dynamic properties of involved material, natural as well as anthropogenic. The area of Rome is affected by earthquakes from different seismogenic districts: i) the central Apennine mountain chain (D = 90–130km and M = 6.7–7.0); ii) the Colli Albani volcanic district (D = 20km and M=5.5); iii) Rome area itself, which is characterized by rare, shallow, low-magnitude events (M < 5). Both natural and artificial signals have been considered to define the input motion for the numerical modeling of the site response of the whole archeological area. This was accomplished by means of the finite differences code FLAC3D. To evaluate the seismic hazard and, consequently, to assess possible priorities for seismic retrofitting of the monuments, contour maps of Housner intensity amplification ratio FH (defined as the ratio between Housner intensity at the top of the model and the corresponding input at the bedrock outcrop), are carried out. To cover the entire range of natural periods pertaining to the monuments in the examined area, FH was evaluated over three ranges of period: 0.1–0.5s, 0.5–1.0s, and 1.0–2.0s. Numerical results shown that: 1) within the range of periods 0.1–0.5s, high values of FH = 2.2–2.6 occur both in correspondence of narrow valleys filled with soft alluvial deposits and at top of Palatine Hill; 2) within the range of periods 0.5–1.0s, high values of FH occur in correspondence of the deepest valleys; 3) within the range of periods 1.0–2.0s, low values of FH occur except in correspondence of the deepest valleys.Results show a good agreement with the previous 2D numerical modeling and with the microzonation maps (Pagliaroli et al 2014a, b), even if interesting differences show up highlighting the usefulness of 3D modeling in such complex settings. Such results are significantly relevant for the monumental and archaeological heritage of this area, as it is highly vulnerable due to its old age and state of conservation

    Use of PSInSAR data to map highly compressible soil layers

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    A new approach to the use of Persistent Scatterers (PS) Interferometry data in the reconstruction of the extension of compressible geological bodies is presented. The methodology was applied in the test area of the Tiber River delta (Italy), characterized by the presence of two large marshy zones, known as the Maccarese and Ostia Antica ponds. PSInSARâ\u84¢ data, derived from ERS1/2, ENVISAT and RADARSAT-1 images, and spanning a time interval between 1992 and 2006 were used to verify the possibility to reconstruct the spatial distribution of the peat levels inside the Maccarese and Ostia Antica ponds. Borehole information was analyzed to calibrate the InSAR data and the deformation rates were used to hypothesize the presence of a thick compressible layer where geological information is lacking. Variations in deformation rates registered by the single PS were assumed to be representative of a variation in the stratigraphic asset. The obtained results demonstrate that this approach could be satisfactorily used to investigate wide areas in a short time, reducing the number of boreholes to drill, and it could be a complementary technique to obtain information about the 2D geometry of specific geological levels

    The evaluation of tactile dysfunction in the hand in type 1 diabetes: a novel method based on haptics

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    Aims We present an innovative method based on haptics for the evaluation of the sense of touch in the hand, in people affected by type 1 diabetes. Methods Forty individuals affected by diabetes and 20 healthy controls took part in the study; the diabetes group was further divided into two subgroups based on vibration sensitivity in the lower limb. By means of a novel haptic device, tactile sensitivity in the fingertip was measured as the ability of the participants to discriminate slip motion speed. Results Tactile sensitivity was significantly lower in individuals affected by diabetes as compared to controls. Depending on the subgroup, the difference from the controls was equal to 0.11 (95% CI from 0.029 to 0.186) and to 0.267 (95% CI from 0.198 to 0.336). Within the diabetes group, tactile sensitivity correlated with vibration sensitivity in the upper (p = 0.001) and lower limb (p = 0.003). A significant relationship between nerve conduction parameters and tactile sensitivity was found (p = 0.03). Finally, we combined the different predictors (clinical, vibratory and electroneurography data) by using cluster analysis; tactile sensitivity was found to be significantly different between different clusters (p = 0.004). Conclusions Early signs of tactile dysfunction in the hand were found in individuals affected by diabetes, even in absence of diabetic neuropathy. The protocol presented in this study is a promising tool for the assessment of tactile dysfunction in the hand in people affected by type 1 diabetes
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