1,141 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)
Water Potential Gradients between Old and Developing Leaves in Lithops (Aizoaceae).
No full textLithops plants consist of a pair of opposite succulent leaves inserted on a short stem. The apical meristem produces a new pair of leaves
within the old one every growing season, recycling water from the old leaves. Since there are no data on water relations between the two
pairs of leaves, we measured leaf water potential at different stages of development with a pressure chamber. Osmotic potential of cell sap
was measured with a cryoscopic osmometer and turgor pressure was calculated indirectly. Leaf water potentials were never very low even
though plants were not irrigated. In old leaves water potential ranged between -0.5 and -0.28 MPa. In young leaves water potential
increased with size from -1.05 to -0.5 MPa and was always lower than in the corresponding old leaves. The water potential gradient
between old and new leaves was steeper in the early stages of development (0.6 MPa) and gradually decreased (0.15 MPa) when young
leaves had almost completed their expansion. Our data show that in Lithops water movement from old to young leaves occurs according
to a water potential gradient. The maintenance of this gradient may be ascribed to differences in turgor pressure, due to the more elastic
and plastic walls of cells of young leaves. The possibility to perform a complete life cycle without external water supply is an extreme
adaptation to the arid environment where Lithops grows
A nested pre-operational model for the Egyptian shelf zone: Model configuration and validation/calibration
No full textWe explored the variability of the Egyptian shelf zone circulation connected to atmospheric forcing by means of a numerical simulation of the general circulation. A high resolution model grid was used at 1/60° horizontal resolution and 25 sigma layers. The simulation was carried out using the most recent version of the Princeton Ocean Model (POM). The initialised model was run the whole year of 2006 using the analysis forcing data for the same year obtained from ECMWF and MFS (Mediterranean Forecasting System, Pinardi et al., 2003). The model skills were evaluated by means of the root mean square error (RMSE) and correlations. The Egyptian Shelf Model (EGYSHM) simulation suggests the presence of an Egyptian Shelf Slope Current (ESSC), which is flowing eastward at different depths in the domain. We found that the maximum velocity of the ESSC [0.25 m/s] is located near the continental slope during the summer time, while in winter the velocity of ESSC is weaker [0.12 m/s] in the same location. The ESSC appears to be directly affected by Mersa-Matruh gyre system. EGYSHM reproduced the main region circulation patterns, especially after adding the Nile River outflow. We found that wind stress is crucial to force the circulation of the Egyptian shelf zone. EGYSHM SST was significantly correlated to satellite SST in all months at a 95% confidence limit, with a maximum of 0.9743 which was obtained in May 2006. The RMSE between EGYSHM and Argo floats salinity data was about 0.09. We compared our results with satellite altimetry to verify the positions and shapes of mesoscale features
EFFECTS OF DIFFERENT WEED CONTROL PRACTICES ON SOIL QUALITY IN MEDITERRANEAN CROPS
No full textQuesta ricerca si occupa di un ramo della sostenibilità ambientale del controllo delle arvensi infestanti, dal punto di vista del mantenimento e del miglioramento della qualità del suolo. Oggi è disponibile sul mercato una vasta gamma di prodotti e di tecniche, ma la stessa definizione di “pratica sostenibile” non sempre tiene in considerazione la fertilità del suolo. I processi che avvengono nel suolo hanno infatti scale temporali più ampie rispetto a quelli produttivi, commerciali e legislativi. Anche la definizione dei protocolli di indagine è un processo più lento rispetto all'evoluzione commerciale dei metodi di controllo delle infestanti. In seguito ad una pressione esterna, la parte dell’ecosistema suolo che reagisce più velocemente sono gli organismi che in esso vivono, e la comunità microbica è in definitiva l’operatore più efficace nel riciclare i nutrienti del suolo.
In questo lavoro gli effetti sul suolo di alcune pratiche di gestione delle infestanti sono stati testati con un protocollo di analisi del suolo standardizzato. Si sono confrontate le variazioni delle proprietà del suolo dopo i diversi trattamenti di controllo delle infestanti.
In particolare è stato monitorato il Carbon pool del suolo e come la comunità microbica del suolo lo ricicla. È stato definito un protocollo standard che permette di valutare l’impatto delle pratiche di controllo delle infestanti sia sulle variazioni a lungo termine nella qualità del suolo, sia quelle a breve termine sui processi biologici.
L'ipotesi di base è che la gestione delle infestanti possa interagire con i processi di riciclaggio dei nutrienti che avvengono ad opera dei microrganismi che vivono nel terreno. Questi processi hanno un ruolo centrale nel mantenimento della fertilità del suolo, una delle risorse più importanti per l'agricoltura. Sotto particolare attenzione sono le pratiche di gestioni delle infestanti dei frutteti: l'uso di erbicidi sintetici (oxyfluorfene), di erbicidi naturali (oli essenziali ed estratti acquosi) e due metodi meccanici (aratura e pacciamatura). La fertilità del terreno è stata monitorata misurando variabili chimico-fisiche del suolo ed elaborando indici di qualità e bioindicatori.This research approaches the question of weed control sustainability, from the point of view of soil quality maintenance and enhancing.
A big choice of practices and products for weed control are available nowadays, but the actual definition of “sustainable practice” not always considers soil fertility. Soil processes timescale is wider than the productive, commercial and legislative ones. Also the definition of survey protocols is a process slower than the evolution of weed control methods.
The faster reaction in the soil ecosystem after an external pressure is given by the organisms living in it, and the microbial community is finally the most effective agent in nutrient recycling processes.
In this investigation, the same soil analysis protocol was applied on soil samples exposed to different weed management and control methods. Using soil quality indexes and bioindicators, soil properties variations after the different weed control treatments were compared. In particular soil carbon pool and how microbial community recycles was surveyed. A standard protocol to both find variations in long-term soil quality and survey the short-term impact of weed control practices on soil biological processes was defined.
Weed management practices can interact with the nutrients recycling processes performed by the microorganisms living in the soil. These processes have a central role in maintaining soil fertility, one of the most important resources for agriculture.
Three weed management practices were compared: the use of synthetic (oxyfluorfen) or natural (essential oils and aqueous extracts) herbicides and two mechanical methods (tillage and mulching).
Soil fertility was monitored measuring soil physical-chemical values and elaborating soil quality indexes and bioindicators
Neural correlates of obsessive-compulsive disorder with the compulsion to wash
No full textThiel A, Oddo S, Langnickel R, Brand M, Markowitsch HJ, Stirn A. Neural correlates of obsessive-compulsive disorder with the compulsion to wash. In: European Psychiatry. EUROPEAN PSYCHIATRY. Vol 23. Cambridge University Press (CUP); 2008
NEUROLOGICAL PROGNOSTICATION AFTER CARDIAC ARREST AND THERAPEUTIC HYPOTHERMIA: A PROSPECTIVE VALIDATION STUDY
No full textForme di intensificazione e identità degeneri. Strategie identitarie ed esempi di alterità nel De reditu suo di Rutilio Namaziano
No full textThis paper focuses on Rutilius Namatianus, praefectus Urbi, who around 417 AD. is forced from Rome to return to his native Gaul, to take care of his possessions. He tells of this journey in De reditu suo, after years of political commitment at the highest levels in the city: during the stops of the journey the author provides large portraits of friends and associates, which he praises virtutes and cursus honorum of. The constant reference to the office of the urban prefecture (or other high government offices) suggests the concern of Rutilius for what makes Rome an excellent place of civilization: temples, roads, aque-ducts, ports, infrastructures that were under direct responsibility of praefectus Urbi. These elements are very significant in the very moment of serious identity crisis in the senatorial class. Rutilius through the portraits of his associates builds the image of a so-cial structure that wants to present itself as the true custodian of the values of the senato-rial class, but not really compact and therefore in need of a renewed identity model. On the other side the invectives and the merciless portraits are served for the "others", the anti-models, who counterbalance this model to be renewed; perhaps the most insidious forms of otherness are the degenerate forms of identical, who - contrary to expectations - deny or subvert the identity model of the senatorial class. Finally, examples of perma-nent liminality are the iuvenis of Gorgona and the shameful lineage of Lepidi, real dys-functional models of identity
ENERGY RETROFIT AND SUSTAINIBILITY. SOCIAL HOUSING ESTATE IN THE MEDITERRANEAN CLIMATE
No full textIn the last years the global attention has increasingly been focusing on climate change and on the depletion of non-renewable energy sources. Recent analyses estimate that the building sector, with construction and activities that allow its normal functioning, is responsible for 50% of global CO2 emissions. In contemporary urban areas, post-war housing estates represent a great percentage of the whole building sector and the amount of new housing produced in EU each year is equivalent to 1% of the whole building stock, which indicates the importance of focusing the attention on the recovery of existing buildings and the optimization of their energetic performances.
The paper will show the first results of a study that is being carried out on a social housing estate in the city of Palermo, aiming to offer a proposal for a sustainable renovation of the district starting from interventions at the micro urban scale for the improvement of the outdoor comfort.
The district original design dates back to the 1970s and includes several social housing buildings that currently present a significant form of decay and very low energy efficiency. After the analysis of the context and the identifications of the problems affecting the district, the local climate will be investigated in order to propose solutions that can improve the inhabitants’ indoor and outdoor comfort. The proposals consist in possible greening scenarios aimed at verifying to what extent vegetation can affect the urban microclimate.
For this reason, simulations were performed by means of the software ENVI-met, which has been essential to quantify the results of the different hypotheses
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
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