63,461 research outputs found
Selective stimulation with intraneural electrodes for bionic limb prostheses can contribute to shed light on human touch sensorimotor integration
No full textA Biomimetic MEMS-based Tactile Sensor Array with Fingerprints integrated in a Robotic Fingertip for Artificial Roughness Encoding
No full textThis work shows the accomplishment of a full integration of a biomimetic 2 à 2 tactile array and related electronics in an artificial fingertip. The technological approach is based on merging 3D MEMS sensors and skin-like artificial materials that are moulded mimicking human epidermal ridges. Experimental results using a mechatronic tactile stimulator for indenting periodic gratings (spatial periodicity from 400 ¿m to 1900 ¿m) and sliding them at constant speeds (from 5 mm/s to 40 mm/s) under regulated normal contact forces (between 100 mN and 400 mN) show that the developed sensing technology is suitable for fine roughness encoding: a frequency shift of the principal spectral component arising from sensor outputs was observed coherently with the spatial periodicity of the used ridged stimuli and their sliding velocity. Such phenomenon is pointed out with fine gratings particularly when the stimulation is operated along the proximal-distal direction of the finger (i.e. with sliding motion of the ridges of the stimulus across the ridges of the packaging) showing a more marked frequency locked behavior if compared to the radial-ulnar stimulation (i.e. with sliding motion of the ridges of the grating along the ridges of the packaging)
Tradeoff between accuracy and computational cost of Euler and Runge Kutta ODE solvers for the Izhikevich spiking neuron model
No full textThe Izhikevich spiking neuron model is one of the most used in neural engineering and computational neuroscience. Due to its trade-off between physiological plausibility and computational efficiency it is being used also in embedded systems with constrained computational resources. Thus, it is crucial to find a compromise between computational cost and error while numerically integrating the equations of the model. This work aims at quantifying the error produced by fixed step Ordinary Differential Equation (ODE) solvers. Our focus is to provide design hints that could be useful for embedded neural engineering applications. We evaluated three types of input and three ODE solvers: Euler, Runge Kutta 2, Runge Kutta 4. First, we generated a dataset of spike trains to draw conclusions on their general behavior while varying the discretization step. Then we showed that, within a single non-interrupting spike train, the spike delay is positive and accumulates linearly with the spike count. Finally, we introduced a robust method to assess the discretization limits. This method exploits the Victor Purpura distance and confirms that the limits depend on the spike train duration. Our results lead the way to a robust and systematic investigation of the trade-off between computational cost and discretization accuracy of fixed step ODE solvers for neuronal models
Effects of temperature on total phenolic compounds in Cystoseira amentacea (C. Agardh) Bory (Fucales, Phaeophyceae) from southern Mediterranean Sea
No full textThe aim of this study was to test the effects of temperature on phenolic content of the brown seaweed Cystoseira amentacea. Phenolic compounds are secondary metabolites involved in different protection mechanisms as, for example, against grazers, epiphytes and UV radiation. Seasonal variations of phenolic content in C. amentacea were analysed and laboratory experiments, in which C. amentacea was exposed to an increase of temperature (25°C and 30°C), were performed. Total phenolic content (TPC) was determined colorimetrically with the Folin–Ciocalteu reagent. In C. amentacea, a seasonal
pattern in TPC was observed, with a maximum value in winter-spring. C. amentacea responded significantly to the temperature treatments with a consistent decrease in TPC after 48 h
Assessing satisfaction of tourists visiting Italian museums: eviden from the eWOM
No full textMuseum visitors’ satisfaction is a priority asset for those museums aiming at being competitive in the cultural tourism sector. In this study, evaluations by visitor-tourists, left in their reviews on museums on the TripAdvisor platform, are analysed. Through web scraping, we collected comments for twelve Italian museums left during the year 2019. The content analysis focussed on components of the tourists’ satisfaction among Italian and foreign museum visitors, with emotional response, management, and exhibitions emerging as key concepts in museum’s evaluation. Noticeably, some elements emerged as divisive: i.e., they appeared both among less and most satisfied tourist-visitor
Long-latency components of somatosensory evoked potentials during passive tactile perception of gratings
No full textPerception of tactile stimuli elicits Somatosensory Evoked Potentials (SEPs) that can be recorded via non-invasive electroencephalography (EEG). However, it is not yet clear how SEPs localization, shape and latency are modulated by different stimuli during mechanical tactile stimulation of fingertips. The aim of this work is thus to characterize SEPs generated by the tactile perception of gratings during dynamic passive stimulation of the dominant fingertip by means of a mechatronic platform. Results show that a random sequence of stimuli elicited SEPs with two long-latency components: (i) a negative deflection around 140 ms located in the frontal-central-parietal side in the contralateral hemisphere; (ii) a positive deflection around 250 ms located in the frontal-central midline. Time-frequency analysis revealed significant continuous bilateral desynchronization in the alpha band throughout the passive stimulation. These results are a fundamental step towards building a model of brain responses during perception of tactile stimuli for future benchmarking studies
A passively regulated full-toroidal continuously variable transmission
No full textThis work presents a novel self-regulated toroidal continuously variable transmission (ART-CVT) that features a passive control of the speed ratio, achieved with no need for supplementary actuation system. The proposed transmission system is based on a full-toroidal CVT topology which combines a specially shaped geometry of the conjugate profiles with a pre-load system to create a correlation between the speed ratio and the input torque. Such a solution is conceived to reduce the complexity that is usually associated with active regulated systems and it is envisaged to be applicable to low-power/low-cost systems such as small wind turbines, powered-two-wheelers, or bicycles. We illustrate a simplified mathematical model that is able to describe the response of the proposed ART-CVT in quasi-static steady-state operational conditions. Additionally, we propose a case-study in a realistic scenario: a design for an ART-CVT that matches the requirements of a low-power wind turbine coupled with a synchronous generator directly connected to the grid without additional power converters. The achieved results show that an ART-CVT is able to reach working conditions close to the maximum theoretical aerodynamic performance without any active regulation
Regulating Internet Trade in CITES Species
No full textWild collection of species that are or may be endangered by collection from the wild for international commerce is regulated under the The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) for 176 member States. Internet commerce is a relatively a new route for such trade and is rarely included in CITES statistics. By comparing information from an international on-line auction system with official CITES records on international trade, we discovered that only around 10% of the specimens of cacti listed on CITES Appendix I traded in 2010 were even potentially legal. Clearly, such trade over the Internet easily bypasses CITES trade regulations and should be monitored in future to ensure the effective protection of CITES listed species
- …
