393 research outputs found
Neural Substrates of Chronic Pain in the Thalamocortical Circuit
Chronic pain (CP), a pathological condition with a large repertory of signs and symptoms, has no recognizable neural functional common hallmark shared by its diverse expressions. The aim of the present research was to identify potential dynamic markers shared in CP models, by using simultaneous electrophysiological extracellular recordings from the rat ventrobasal thalamus and the primary somatosensory cortex. We have been able to extract a neural signature attributable solely to CP, independent from of the originating conditions. This study showed disrupted functional connectivity and increased redundancy in firing patterns in CP models versus controls, and interpreted these signs as a neural signature of CP. In a clinical perspective, we envisage CP as disconnection syndrome and hypothesize potential novel therapeutic appraisal
Chirality in halogen-bonded supramolecular architectures
Abstracts of the XXII IUCr Congres
Perfluoropolyethers coatings design for fouling reduction on heat transfer stainless steel surfaces
The scope of this research is to obtain a film coating on stainless steel surfaces in order to reduce the interaction between the metal surface and the precipitates, so to mitigate fouling in heat exchangers. Perfuoropolyethers were used to obtain nano-range fluorinated layers in order to make hydrophobic the stainless steel surfaces. A pilot plant with two identical heat exchangers was built to investigate the ability of the hydrophobic coating of preventing fouling. The heat exchangers, installed in parallel, operated at the same temperature and pressure conditions, i.e. laminar flow regime and inlet flow temperatures of 291\u2013293 K for cold streams and 313\u2013333 K for hot streams. We compared the heat transfer performance of the two heat exchangers. After a five months operation the decrease in the heat transferred was 56% for the coated heat exchanger and 62% for the uncoated heat exchanger. Moreover, the increase of heat transfer resistance due to scale on the uncoated heat exchanger, with respect to the coated one, was three times higher
Applicability of an orthogonal cutting slip-line field model for the microscale
Mechanical micromachining is a very flexible and widely exploited process, but its knowledge should still be improved
since several incompletely explained phenomena affect the microscale chip removal. Several models have been developed
to describe the machining process, but only some of them consider a rounded edge tool, which is a typical condition in
micromachining. Among these models, the Waldorf’s slip-line field model for the macroscale allows to separately evaluate
shearing and ploughing force components in orthogonal cutting conditions; therefore, it is suitable to predict cutting
forces when a large ploughing action occurs, as in micromachining. This study aims at demonstrating how this model is
suitable also for micromachining conditions. To achieve this goal, a clear and repeatable procedure has been developed
for objectively validating its force prediction performance at low uncut chip thickness (less than 50 mm) and relatively
higher cutting edge radius. The proposed procedure makes the model generally applicable after a suitable and nonextensive
calibration campaign. This article shows how calibration experiments can be selected among the available cutting
trial database based on the model force prediction capability. Final validation experiments have been used to show
how the model is robust to a cutting speed variation even if the cutting speed is not among the model quantities. A suitable
set-up, especially designed for microturning conditions, has been used to measure forces and chip thickness. Tests
have been performed on 6082-T6 Aluminum alloy with different cutting speeds and different ratios between uncut chip
thickness and cutting edge radius
Optimization of a 3D dynamic culturing system for in vitro modeling of Frontotemporal Neurodegeneration-relevant pathologic features
Frontotemporal lobar degeneration (FTLD) is a severe neurodegenerative disorder that is diagnosed with increasing frequency in clinical setting. Currently, no therapy is available and in addition the molecular basis of the disease are far from being elucidated. Consequently, it is of pivotal importance to develop reliable and cost-effective in vitro models for basic research purposes and drug screening. To this respect, recent results in the field of Alzheimer’s disease have suggested that a tridimensional (3D) environment is an added value to better model key pathologic features of the disease. Here, we have tried to add complexity to the 3D cell culturing concept by using a microfluidic bioreactor, where cells are cultured under a continuous flow of medium, thus mimicking the interstitial fluid movement that actually perfuses the body tissues, including the brain. We have implemented this model using a neuronal-like cell line (SH-SY5Y), a widely exploited cell model for neurodegenerative disorders that shows some basic features relevant for FTLD modeling, such as the release of the FTLD-related protein progranulin (PRGN) in specific vesicles (exosomes). We have efficiently seeded the cells on 3D scaffolds, optimized a disease-relevant oxidative stress experiment (by targeting mitochondrial function that is one of the possible FTLD-involved pathological mechanisms) and evaluated cell metabolic activity in dynamic culture in comparison to static conditions, finding that SH-SY5Y cells cultured in 3D scaffold are susceptible to the oxidative damage triggered by a mitochondrial-targeting toxin (6-OHDA) and that the same cells cultured in dynamic conditions kept their basic capacity to secrete PRGN in exosomes once recovered from the bioreactor and plated in standard 2D conditions. We think that a further improvement of our microfluidic system may help in providing a full device where assessing basic FTLD-related features (including PRGN dynamic secretion) that may be useful for monitoring disease progression over time or evaluating therapeutic interventions
alternating dynamics of segregation and integration in human eeg functional networks during working memory task
Abstract Brain functional networks show high variability in short time windows but mechanisms governing these transient dynamics remain unknown. In this work, we studied the temporal evolution of functional brain networks involved in a working memory (WM) task while recording high-density electroencephalography (EEG) in human normal subjects. We found that functional brain networks showed an initial phase characterized by an increase of the functional segregation index followed by a second phase where the functional segregation faded after the prevailing the functional integration. Notably, wrong trials were associated with different or disrupted sequences of the segregation-integration profiles and measures of network centrality and modularity were able to identify crucial aspects of the oscillatory network dynamics. Additionally, computational investigations further supported the experimental results. The brain functional organization may respond to the information processing demand of a WM task following a 2-step atomic scheme wherein segregation and integration alternately dominate the functional configurations
An analysis of the first-arrival times picked on the DSS and wide-angle seismic section recorded in Italy since 1968
We performed an analysis of refraction data recorded in Italy since 1968 in the frame of the numerous deep seismic
sounding and wide-angle reflection/refraction projects. The aims of this study are to construct a parametric
database including the recording geometric information relative to each profile, the phase pickings and the results
of some kinematic analyses performed on the data, and to define a reference 1D velocity model for the Italian
territory from all the available refraction data. As concerns the first goal, for each seismic section we picked
the P-wave first-arrival-times, evaluated the uncertainties of the arrival-times pickings and determined from each
travel time-offset curve the 1D velocity model. The study was performed on 419 seismic sections. Picking was
carried out manually by an algorithm which includes the computation of three picking functions and the picking-
error estimation. For each of the travel time-offset curves a 1D velocity model has been calculated. Actually,
the 1D velocity-depth functions were estimated in three different ways which assume: a constant velocitygradient
model, a varying velocity-gradient model and a layered model. As regards the second objective of this
work, a mean 1D velocity model for the Italian crust was defined and compared with those used for earthquake
hypocentre locations and seismic tomographic studies by different institutions operating in the Italian area, to
assess the significance of the model obtained. This model can be used in future works as input for a next joint
tomographic inversion of active and passive seismic data
Caratterizzazione della risposta sismica nella città di Benevento.
L'ampiezzà de1 moto del suolo, ed il suo contenuto in frequenza, alla súpeúcie
della TerIa dÃpede dale caratte stiche della, sorgente sismica e dalle
proprietà meccaniche del úezzo in cui si propagano le onde sismiche. In pa.rtico
lare, gli strati pmssimi alla superficie possono modifrcare in modo sigdficativo
il segnale sismlco. InJatti la presenza, di uno strato con un fo e contraato di im
pedenza, spetto ad un basarnento sottostà nte prÌò indurc etretti di risonanza
alterando sensibilmente il livelo di anpiezza, il conterùto in Îrequenza e la, durata
delle oscilla.zioni del suolo. Un esempio estîemo di questo fenomeno è stato
evidenziatoi n occasiored el terremoto di Michoacan,M essico,d el 1985.Q uesto
evento, pur essendo a-r.venuto ad alcune centinaia di chilometri da.lla capitale,
ha, eccitato con il pe.iodo proprio di oscillnzioÈe( cilca 2 secondi)i depositi di
riempimento di un antico lago prosciugato, su cui è costruita parte di Città , del
Messico, pmvocaùdo iI crollo di nurerosi edifici e misliaia di morti (Singh et
al., 198
K+ accumulation and clearance in the calyx synaptic cleft of type I mouse vestibular hair cells
Vestibular organs of Amniotes contain two types of sensory cells, named Type I and Type II hair cells. While Type II hair cells are contacted by several small bouton nerve terminals, Type I hair cells receive a giant terminal, called a calyx, which encloses their basolateral membrane almost completely. Both hair cell types release glutamate, which depolarizes the afferent terminal by binding to AMPA post-synaptic receptors. However, there is evidence that non-vesicular signal transmission also occurs at the Type I hair cell-calyx synapse, possibly involving direct depolarization of the calyx by K+ exiting the hair cell. To better investigate this aspect, we performed whole-cell patch-clamp recordings from mouse Type I hair cells or their associated calyx. We found that [K+] in the calyceal synaptic cleft is elevated at rest relative to the interstitial (extracellular) solution and can increase or decrease during hair cell depolarization or repolarization, respectively. The change in [K+] was primarily driven by GK,L, the low-voltage-activated, non-inactivating K+ conductance specifically expressed by Type I hair cells. Simple diffusion of K+ between the cleft and the extracellular compartment appeared substantially restricted by the calyx inner membrane, with the ion channels and active transporters playing a crucial role in regulating intercellular [K+]. Calyx recordings were consistent with K+ leaving the synaptic cleft through postsynaptic voltage-gated K+ channels involving KV1 and KV7 subunits. The above scenario is consistent with direct depolarization and hyperpolarization of the calyx membrane potential by intercellular K+
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