1,721,780 research outputs found
The contribution of resident vascular stem cells to arterial pathology
No full textIntimal accumulation of smooth muscle cells contributes to the development and progression of atherosclerotic lesions and restenosis following endovascular procedures. Arterial smooth muscle cells display heterogeneous phenotypes in both physiological and pathological conditions. In response to injury, dedifferentiated or synthetic smooth muscle cells proliferate and migrate from the tunica media into the intima. As a consequence, smooth muscle cells in vascular lesions show a prevalent dedifferentiated phenotype compared to the contractile appearance of normal media smooth muscle cells. The discovery of abundant stem antigen-expressing cells in vascular lesions also rarely detected in the tunica media of normal adult vessels stimulated a great scientific debate concerning the possibility that proliferating vascular wall-resident stem cells accumulate into the neointima and contribute to the progression of lesions. Although several experimental studies support this hypothesis, others researchers suggest a positive effect of stem cells on plaque stabilization. So, the real contribute of vascular wall-resident stem cells to pathological vascular remodelling needs further investigation. This review will examine the evidence and the contribution of vascular wall-resident stem cells to arterial pathobiology, in order to address future investigations as potential therapeutic target to prevent the progression of vascular diseases
Advances in numerical solution algorithms for time domain MTL equations
No full textThis paper is primarily a guide for computer-implementing the direct time domain solution of the Multiconductor Transmission Line equations. The numerical treatment of frequency dependent conductor losses and generic termination of the lines are discussed highlighting the main problems and their solutions
Instrument-specific effects of musical expertise on audiovisual processing (Clarinet vs. Violin)
No full textA large body of evidence has shown that musicians' brains differ in many ways from nonmusicians' brains due to the particularly intense and prolonged sensorimotor training involved. Not much is known about the effects of the specific musical instrument played on brain processing of audiovisual information. In this study the effect of musical expertise was investigated in professional clarinetists and violinists. One hundred and eighty videos showing fragments of musical performances played on a violin or a clarinet were presented to musicians of G. Verdi Milan Conservatory and age-matched controls. Half of the musicians were violinists, the other half were clarinetists; eventrelated potentials (ERPs) were recorded from 128 scalp sites and analyzed. Participants judged how many notes were played in each clip. The task was extremely easy for all participants. Over prefrontal areas an anterior negativity response was found to be much larger in controls than in musicians, and in musicians for the unfamiliar over the familiar musical instrument. Furthermore, a later central negativity response showed a lack of note numerosity effect in the brains of musicians for their own instrument, but not for unfamiliar instrument. The data indicate that music training is instrument-specific and that it profoundly affects prefrontal encoding of music-related information and auditory processing
Left-hemispheric asymmetry for object-based attention: an ERP study
Full text linkIt has been shown that selective attention enhances the activity in visual regions associated with stimulus processing. The left hemisphere seems to have a prominent role when non-spatial attention is directed towards specific stimulus features (e.g., color, spatial frequency). The present electrophysiological study investigated the time course and neural correlates of object-based attention, under the assumption of left-hemispheric asymmetry. Twenty-nine right-handed participants were presented with 3D graphic images representing the shapes of different object categories (wooden dummies, chairs, structures of cubes) which lacked detail. They were instructed to press a button in response to a target stimulus indicated at the beginning of each run. The perception of non-target stimuli elicited a larger anterior N2 component, which was likely associated with motor inhibition. Conversely, target selection resulted in an enhanced selection negativity (SN) response lateralized over the left occipito-temporal regions, followed by a larger centro-parietal P300 response. These potentials were interpreted as indexing attentional selection and categorization processes, respectively. The standardized weighted low-resolution electromagnetic tomography (swLORETA) source reconstruction showed the engagement of a fronto-temporo-limbic network underlying object-based visual attention. Overall, the SN scalp distribution and relative neural generators hinted at a left-hemispheric advantage for non-spatial object-based visual attentio
Bilateral engagement of the occipito-temporal cortex in response to dance kinematics in experts
Full text linkPrevious evidence has shown neuroplastic changes in brain anatomy and connectivity associated with the acquisition of professional visuomotor skills. Reduced hemispherical asymmetry was found in the sensorimotor and visual areas in expert musicians and athletes compared with non-experts. Moreover, increased expertise with faces, body, and objects resulted in an enhanced engagement of the occipito-temporal cortex (OTC) during stimulus observation. The present study aimed at investigating whether intense and extended practice with dance would result in an enhanced symmetric response of OTC at an early stage of action processing. Expert ballet dancers and non-dancer controls were presented with videos depicting ballet steps during EEG recording. The observation of the moving dancer elicited a posterior N2 component, being larger over the left hemisphere in dancers than controls. The source reconstruction (swLORETA) of the negativity showed the engagement of the bilateral inferior and middle temporal regions in experts, while right-lateralized activity was found in controls. The dancers also showed an early P2 and enhanced P300 responses, indicating faster stimulus processing and subsequent recognition. This evidence seemed to suggest expertise-related increased sensitivity of the OTC in encoding body kinematics. Thus, we speculated that long-term whole-body practice would result in enriched and refined action processin
Effect of environmental data uncertainty in the framework of second generation intact stability criteria
Full text linkThe framework of second generation intact stability criteria in MSC.1/Circ.1627 includes a number of novelties for intact stability assessment. One of such novelties is the inherent possibility of designing a vessel for a specific operational area, by embedding area-specific environmental conditions. This is practically achieved through modification of the relevant calculation parameters in the criteria, on the basis of available MetOcean data. However, MetOcean data for a given area are generally available from multiple sources, and different sources provide information on environmental conditions on the basis of different approaches. This leads to a source-related variability that eventually reflects in the results of stability assessment, to an extent that is yet to be fully explored. The present study aims at providing quantitative indications in this respect. The Mediterranean Sea is considered as operational area, five different sources of MetOcean data are used, and level 1 and level 2-check 1 vulnerability criteria for parametric rolling are applied to two sample ships. The variability in the obtained safe zones of loading conditions is presented and discussed, also with reference to the effect of bilge keels. Some difficulties in the practical implementation of the procedure for embedding operational limitations are also highlighted and discussed
ERP indices of an orientation-dependent recognition of the human body schema
No full textWhile it is well-established that the face perception is orientation-dependent, less evidence has been provided on the effects of the orientation on the body schema processing and related attentive mechanisms. Poorer performance in same/different judgment tasks and increased occipito-temporal N1 response to the inverted (vs. upright) body schema seem to hint at an orientation-dependent perceptual mechanism. The present electrophysiological study investigated the role of attentive selection processes required to recognize the inverted (vs. upright) body schema by means of the event-related potentials (ERP). 320 different images depicting body shapes (wooden dummies) as opposed to random structures of cubes were created in 3D graphics. Thirty-two right-handed participants were presented with the stimuli in an upright and inverted orientation. They were required to alternatively recognize one of the two categories of stimuli (by button press) regardless of the orientation, during EEG recording. The body inversion led to increased reaction times during body schema recognition. A slower anterior N2, larger N1, Selection Negativity (SN), and increased parietal P300 components were elicited by the perception of the inverted body schema. Slower stimulus processing and increased attention allocation were associated with the processing of the inverted body schema. The swLORETA source reconstruction (in the SN time window) showed enhanced engagement of prefrontal, limbic, and temporal regions during the perception of the inverted body schema. At the same time, the cubes’ orientation did not affect ERP amplitudes. Overall, these pieces of evidence seem to suggest a crucial role of the upright orientation in the visual recognition of the human body schema
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