57 research outputs found
EEG theta dynamics within frontal and parietal cortices for error processing during reaching movements in a prism adaptation study altering visuo-motor predictive planning
Modulation of frontal midline theta (fmθ) is observed during error commission, but little is known about the role of theta oscillations in correcting motor behaviours. We investigate EEG activity of healthy partipants executing a reaching task under variable degrees of prism-induced visuo-motor distortion and visual occlusion of the initial arm trajectory. This task introduces directional errors of different magnitudes. The discrepancy between predicted and actual movement directions (i.e. the error), at the time when visual feedback (hand appearance) became available, elicits a signal that triggers on-line movement correction. Analysis were performed on 25 EEG channels. For each participant, the median value of the angular error of all reaching trials was used to partition the EEG epochs into high- and low-error conditions. We computed event-related spectral perturbations (ERSP) timelocked either to visual feedback or to the onset of movement correction. ERSP time-locked to the onset of visual feedback showed that fmθ increased in the high-but not in the lowerror condition with an approximate time lag of 200 ms. Moreover, when single epochs were sorted by the degree of motor error, fmθ started to increase when a certain level of error was exceeded and, then, scaled with error magnitude. When ERSP were time-locked to the onset of movement correction, the fmθ increase anticipated this event with an approximate time lead of 50 ms. During successive trials, an error reduction was observed which was associated with indices of adaptations (i.e., aftereffects) suggesting the need to explore if theta oscillations may facilitate learning. To our knowledge this is the first study where the EEG signal recorded during reaching movements was time-locked to the onset of the error visual feedback. This allowed us to conclude that theta oscillations putatively generated by anterior cingulate cortex activation are implicated in error processing in semi-naturalistic motor behaviours. © 2016 Arrighi et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Peripheral Purinergic Modulation in Pediatric Orofacial Inflammatory Pain Affects Brainstem Nitroxidergic System: A Translational Research
Physiology of orofacial pain pathways embraces primary afferent neurons, pathologic changes in the trigeminal ganglion, brainstem nociceptive neurons, and higher brain function regulating orofacial nociception. The goal of this study was to investigate the nitroxidergic system alteration at brainstem level (spinal trigeminal nucleus), and the role of peripheral P2 purinergic receptors in an experimental mouse model of pediatric inflammatory orofacial pain, to increase knowledge and supply information concerning orofacial pain in children and adolescents, like pediatric dentists and pathologists, as well as oro-maxillo-facial surgeons, may be asked to participate in the treatment of these patients. The experimental animals were treated subcutaneously in the perioral region with pyridoxalphosphate-6-azophenyl-2′,4′-disulphonic acid (PPADS), a P2 receptor antagonist, 30 minutes before formalin injection. The pain-related behavior and the nitroxidergic system alterations in the spinal trigeminal nucleus using immunohistochemistry and western blotting analysis have been evaluated. The local administration of PPADS decreased the face-rubbing activity and the expression of both neuronal and inducible nitric oxide (NO) synthase isoforms in the spinal trigeminal nucleus. These results underline a relationship between orofacial inflammatory pain and nitroxidergic system in the spinal trigeminal nucleus and suggest a role of peripheral P2 receptors in trigeminal pain transmission influencing NO production at central level. In this way, orofacial pain physiology should be elucidated and applied to clinical practice in the futur
Results from shallow geophysical investigations in the northwestern sector of the island of Malta
We performed geophysical investigations in the northwestern sector of the island of Malta to reconstruct velocity-depth models and provide shear-wave velocity profiles. We have chosen two sites, one located in Rabat (Malta) and another in the Golden Bay area. We used both active (seismic and electrical 2D-tomography, Multichanel Analysis of Surface Waves – MASW) and passive (2D arrays and single-station measurements using ambient noise) geophysical methods. Consistently with previous studies performed in this part of Malta, we have found that both sites are characterised by site resonance in the frequency range 1-2 Hz as an effect of the local lithostratigraphic succession that shows an impedance contrast at about 60-90 m depth. This resonance effect can have important implications on both seismic hazard as well as seismic risk evaluation of the region since the amplified frequency range coincides with the resonance frequencies typical of 5–10 storey buildings which are very diffuse in the Maltese Islands, especially after intense recent urbanization.Published41-484T. Sismologia, geofisica e geologia per l'ingegneria sismicaJCR Journa
Sub-surface characterization of the Anphiteatrum Flavium Area (Rome, Italy) through single-station ambient vibration measurements
The Amphiteatrum Flavium in Rome (Italy) is one of the most known monument in the world. With the aim of understand the seismic response of the area where the Amphiteatrum Flavium is build and investigate possible soil-structure interactions, we performed a seismic experiment in 2014, based on ambient vibration (AMV) recordings. The measurements were performed at the original ground level, on the foundation and at different floors of the monument. Data were analyzed in terms of standard Fourier analysis (FAS) and horizontal-to-vertical spectral ratio technique (H/V). Moreover, we performed an active P-wave seismic tomography analysis of the foundation materials to better understand their influence on the recorded signals. Our results point out that there is a strong temporal and spatial stability of the H/V curves, suggesting a uniform seismic response at the monument site. Conversely, spectral amplitudes of AMV show relevant temporal and spatial variability at the investigated site, due to the daily variations of AMV levels and to the low-pass filtering effect of the stiff Amphiteatrum Flavium foundation that strongly attenuates the signals for frequencies above 4 Hz, i.e. those mostly originated by traffic vibrations. Moreover, we observe that the main vibration frequencies of the super-structure are not present as energetic peaks in the spectra of the ground-motion recorded at its base
Site effect studies following the 2016 Mw 6.0 Amatrice Earthquake (Italy): the Emersito Task Force activities
On August 24, 2016, at 01:36 UTC a MW 6.0 earthquake struck an extensive area of the Central Apennines (Italy) be-tween the towns of Norcia and Amatrice. Due to the mainshock magnitude and the widespread damaging level of build-ings in the epicentral area, the Emersito task force has been mobilized by the Istituto Nazionale di Geofisica e Vulcanologia (INGV). The aim of Emersito is to carry out and coordinate the monitoring of local site effects, caused by geological and geomorphological settings. During the first days of the seismic emergency, Emersito installed a tempo-rary seismic network for site effect studies at 4 municipalities close to the epicentral area (Amandola, Civitella del Tronto, Montereale and Capitignano), using 22 stations equipped with both velocimetric and accelerometric sensors. The selection of the sites where stations have been installed was mainly driven by the proximity to the epicentral area (without interfere with the rescue operations) and by peculiar geologic and geomorphologic settings (topographic irregu-larities, fault zones, alluvial plains). Preliminary analyses performed on ambient noise and aftershocks signals show that directional amplification effects may have occurred at stations installed on the top of topographic irregularities. We also observed the lengthening and amplification of the seismograms and a variability of the peaked frequency across the sedi-mentary basin between Montereale and Capitignano, probably related to a different thickness of the deposits. Further analyses are necessary to assess the correlation with surface geology.Published4T. Sismologia, geofisica e geologia per l'ingegneria sismica1SR. TERREMOTI - Servizi e ricerca per la SocietĂ 1IT. Reti di monitoraggioJCR Journa
Temporary dense seismic network during the 2016 Central Italy seismic emergency for microzonation studies
In August 2016, a magnitude 6.0 earthquake struck Central Italy, starting a devastating seismic sequence, aggravated by other two events of magnitude 5.9 and 6.5, respectively. After the first mainshock, four Italian institutions installed a dense temporary network of 50 seismic stations in an area of 260 km2. The network was registered in the International Federation of Digital Seismograph Networks with the code 3A and quoted with a Digital Object Identifier ( https://doi.org/10.13127/SD/ku7Xm12Yy9 ). Raw data were converted into the standard binary miniSEED format, and organized in a structured archive. Then, data quality and completeness were checked, and all the relevant information was used for creating the metadata volumes. Finally, the 99 Gb of continuous seismic data and metadata were uploaded into the INGV node of the European Integrated Data Archive repository. Their use was regulated by a Memorandum of Understanding between the institutions. After an embargo period, the data are now available for many different seismological studies.Publishedid 1825T. Sismologia, geofisica e geologia per l'ingegneria sismicaJCR Journa
Energy efficiency analysis of an entire ceramic kiln: A numerical approach
The paper focuses on the numerical analysis of an industrial ceramic kiln to improve the energy efficiency and the fuel consumption as well as the pollutant emissions. The entire ceramic kiln is modelled by means of a lumped and distributed parameter model; particular care is devoted to the modelling of the heat transfer phenomena occurring within the system under actual operating conditions. Models for the simulation of the different components that are used for the kiln functioning are included in the modelling, such as the burners, the fan, the valves and the control system. The numerical approach demonstrates to predict accurately the temperature distribution of both the tiles and the hot gases along the kiln length. Numerical results are validated against experimental measurements carried out on a real ceramic kiln during regular production operations. The developed numerical approach demonstrates to be an efficient tool for investigating different design solutions for the kiln's components as well as for developing new control strategies. The kiln numerical model is employed to compare different configurations of heat recovery and solutions for improving the tiles' heat transfer. The considered designs are simulated and the performance in terms of energy efficiency and fuel consumption is determined
Lumped Parameters Numerical Simulation of a Variable Displacement Vane Pump for High Speed ICE Lubrication
In this paper a detailed analysis focused on lumped parameters numerical modelling of a variable displacement vane pump for high-speed internal combustion engine lubrication is presented and discussed. This particular volumetric unit is characterized by very extreme performance, both in terms of rotational speed, delivery pressure and displacement variation.First of all, a comprehensive description of the simulation environment properly tailored for the numerical modelling of the vane pump operation is introduced and all its geometric, kinematic and fluid-dynamic characteristics are described in depth. Then, the results coming from an exhaustive experimental campaign have been compared with simulations, finding a general good accordance that demonstrates the reliability of this numerical approach. Finally, the capabilities of the validated model have been applied to investigate the influence exerted by the main geometrical parameters and internal leakages on the pump fluid dynamic behavior
A Lumped Parameter Approach for Simulation of ICE Cooling Systems
In this paper a detailed analysis focused on lumped parameters numerical modeling of high speed direct injected internal combustion engine cooling systems is presented and discussed. More in details, the cooling systems here studied are characterized by extreme performance, both in terms of circulating flow rates and thermal loads. First of all, a comprehensive description of the simulation environment properly tailored for cooling systems modeling is introduced and all its geometric, fluid-dynamic and thermodynamic characteristics are described in depth. Then, the model has been validated through an exhaustive numerical vs. experimental comparison, involving both cold and hot engine operation, for a wide range of rotational speeds. The general good accordance obtained between calculated and measured results clearly demonstrate the reliability of the numerical model. Finally, the main capabilities of the lumped parameters model as a useful design tool have been evidently showed by investigating different cooling circuit configurations and comparing the results here obtained with the baseline solution
Primi Risultati dello Sviluppo di un Motore Diesel Veloce a Due Tempi di Nuova Concezione
Fin dall’inizio degli anni Novanta, numerosi tentativi sono stati fatti per applicare il ciclo a due tempi ai motori Diesel veloci: si ricordano ad esempio i prototipi automobilistici realizzati da Toyota, Yamaha e AVL; nel campo aeronautico vi sono addirittura già alcuni esemplari in commercio (DeltaHawk, Zoche, Diesel Air, Wilksh Airmotive). La superiorità del Diesel due tempi rispetto al quattro tempi è ormai accertata in termini di rapporto peso-potenza ed emissioni di NOx; qualche dubbio sussiste tuttavia per quello che riguarda il consumo specifico e le emissioni di particolato. All’interno del Dipartimento di Ingegneria Meccanica e Civile dell’Università di Modena e Reggio Emilia è attivo da qualche tempo un progetto che ha come iniziale obiettivo lo studio della fattibilità e la previsione delle prestazioni di un nuovo tipo di motore a due tempi Diesel veloce. Tale studio, i cui principali risultati finora ottenuti sono presentati in questo articolo, si avvale principalmente di simulazioni CFD, sia mono che multi-dimensionali, includendo anche la combustione. Per poter valutare le potenzialità del nuovo motore si è assunto come riferimento un motore a quattro tempi Diesel automobilistico, del quale sono note sperimentalmente tutte le caratteristiche e di cui si sono effettuate anche svariate simulazioni. Dal confronto finora effettuato tra il quattro tempi di riferimento ed il nuovo motore due tempi, sono emerse indicazioni estremamente confortanti circa la validità del concetto proposto
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