770 research outputs found
Selective stimulation with intraneural electrodes for bionic limb prostheses can contribute to shed light on human touch sensorimotor integration
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Risposte agli stress ambientali in CYSTOSEIRA (C. AGARDH): effetti della temperatura sul contenuto dei composti fenolici
No full textPhenolic 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 (258C and 308C), 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
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
Administration of a selective beta 2 adrenergic receptor antagonist exacerbates neuropathology and cognitive deficits in a mouse model of Alzheimer's disease
No full textCurrently, there are no available approaches to cure or slow down the progression of Alzheimer's disease (AD), which is characterized by the accumulation of extracellular amyloid-beta (A beta) deposits and intraneuronal tangles that comprised hyperphosphorylated tau. The beta 2 adrenergic receptors (beta 2ARs) are expressed throughout the cortex and hippocampus and play a key role in cognitive functions. Alterations in the function of these receptors have been linked to AD; however, these data remain controversial as apparent contradicting reports have been published. Given the current demographics of growing elderly population and the high likelihood of concurrent beta-blocker use for other chronic conditions, more studies into the role of this receptor in AD animal models are needed. Here, we show that administration of ICI 118,551 (ICI), a selective beta 2AR antagonist, exacerbates cognitive deficits in a mouse model of AD, the 3xTg-AD mice. Neuropathologically, ICI increased A beta levels and A beta plaque burden. Concomitantly, ICI-treated 3xTg-AD mice showed an increase in tau phosphorylation and accumulation. Mechanistically, these changes were linked to an increase in amyloidogenic amyloid precursor protein processing. These results suggest that under the conditions used here, selective pharmacologic inhibition of beta 2ARs has detrimental effects on AD-like pathology in mice. Overall, these studies strengthen the notion that the link between beta 2ARs and AD is likely highly complex and suggest caution in generalizing the beneficial effects of beta blockers on AD. (C) 2014 Elsevier Inc. All rights reserved
Forme 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
A 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)
Total phenolic content in brown algae from the Sicilian coast
No full textPhlorotannins are polyphenolic secondary metabolites found in almost all brown algae that function as defense against grazers, pathogens and epiphytes but are also involved in photoprotection mechanisms. These com- pounds, produced in the Golgi apparatus, are accumulated in cytoplasm, within vesicules called physodes, or bound to the cell wall. The concentration of phlorotannins differs within and between species, shows geograph- ical variations but may be also affected by abiotic or biotic factors. We present here an overview of the studies carried out on total phenolic content in brown algae collected along the north-western coast of Sicily. The aims of these studies were in particular a) to analyse total phenolic content in four Mediterranean brown algae (Cys toseira amentacea, Cystoseira compressa, Dictyopteris polypodioides and Padina pavonica), b) to follow the sea- sonal changes in total phenolic content in D. polypodioides and C. amentacea and c) to test the effects of temperature on total phenolic content of C. amentacea. Results showed signiicant differences in total phenolic content between leathery and sheet-like algae and also within each morphological group. Among the four species, the sheet-like alga D. polypodioides showed the highest concentration of phenolic compounds. Differ- ences in the seasonal pattern of total phenolic content and in the period of maximum production were observed between D. polypodioides and C. amentacea. In D. polypodioides the peak was observed during winter and autumn whereas for C. amentacea the peak was observed during spring and summer. Moreover, C. amentacea responded signiicantly to the exposition to an increase of temperature, suggesting that increasing global temperatures predicted in the coming century might have effects on the chemical defences and then on the trophic interactions of these algae. The results of these studies seem to conirm that total phenolic content in brown algae is a re- sponse to a combination of several factors. However, due to the complexity of total phenolic content responses in brown algae and the multiple roles of phlorotannins, for a better understanding of this process, it is still nec- essary to identify which types of phlorotannins are responsible for the different activities in order to clarify who does what. Therefore, studies are currently in progress in order to characterize phlorotannins in some species belonging to the Fucales and Dictyotales and to test their biological activities
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