TESSUTI MIMMA GINI

Storia di un brand che ha saputo fondere artigianato indiano e stile europe

Building response to tunnelling

AbstractUnderstanding how buildings respond to tunnelling-induced ground movements is an area of great importance for urban tunnelling projects, particularly for risk management. In this paper, observations of building response to tunnelling, from both centrifuge modelling and a field study in Bologna, are used to identify mechanisms governing the soil–structure interaction. Centrifuge modelling was carried out on an 8-m-diameter beam centrifuge at Cambridge University, with buildings being modelled as highly simplified elastic and inelastic beams of varying stiffness and geometry. The Bologna case study presents the response of two different buildings to the construction of a sprayed concrete lining (SCL) tunnel, 12m in diameter, with jet grouting and face reinforcement.In both studies, a comparison of the building settlement and horizontal displacement profiles, with the greenfield ground movements, enables the soil structure interaction to be quantified. Encouraging agreement between the modification to the greenfield settlement profile, displayed by the buildings, and estimates made from existing predictive tools is observed. Similarly, both studies indicate that the horizontal strains, induced in the buildings, are typically at least an order of magnitude smaller than the greenfield values. This is consistent with observations in the literature. The potential modification to the settlement distortions is shown to have significant implications on the estimated level of damage. Potential issues for infrastructures connected to buildings, arising from the embedment of rigid buildings into the soil, are also highlighted

BREAKDOWN OF CAUSALITY AND CORTICAL DOWNSTATE WITHIN THE SLEEPING BRAIN

Theoretically, consciousness depends on the brain\u2019s ability to engage in complex activity patterns that are, at once, distributed among interacting cortical areas (integrated) and differentiated in space and time (information-rich). In a recent series of experiments the electroencephalographic response to a direct cortical stimulation in humans was recorded during wakefulness and non-rapid eyes movement sleep (NREM) by means of a combination of transcranial magnetic stimulation (TMS) and high-density electroencephalogram (hd-EEG). TMS/hd-EEG measurements showed that, while during wakefulness the brain is able to sustain long-range specific patterns of activation, during NREM sleep, when consciousness fades, this ability is lost: the thalamocortical system, despite being active and reactive, either breaks down in causally independent modules (producing a local slow wave), or it bursts into an explosive and non-specific response (producing a global EEG slow wave). We hypothesize that, like spontaneous sleep slow waves, the slow waves triggered by TMS during deep sleep are due to bistability between periods of hyperpolarized down-state in cortical neurons, and periods of activation (up-state). In this condition, the inescapable occurrence of a silent, down-state after an initial activation could impair the ability of thalamocortical circuits to sustain long-range, differentiated patterns of activation, a theoretical requisite for consciousness. According to animal experiments the extracellular signature of the downstate is a transient suppression of high frequency (20Hz) oscillations \u2013 that is followed by a loss of both PLF and PLV, in spite of restored levels of neuronal activity. These results point to bistability as the underlying critical mechanism that prevents the emergence of complex interactions in human thalamocortical networks when consciousness is lost during NREM sleep. This finding is particularly relevant because a similar mechanism may play a role in other conditions where loss of consciousness is paralleled by the appearance of spontaneous (or TMS evoked) slow waves such as some kind of anesthesia and in brain injured subjects

Loss of consciousness is related to hyper-1 correlated gamma-band activity in anesthetized macaques and sleeping humans

Loss of consciousness can result from a wide range of causes, including natural sleep and pharmacologically induced anesthesia. Important insights might thus come from identifying neuronal mechanisms of loss and re-emergence of consciousness independent of a specific manipulation. Therefore, to seek neuronal signatures of loss of consciousness common to sleep and anesthesia we analyzed spontaneous electrophysiological activity recorded in two experiments. First, electrocorticography (ECoG) acquired from 4 macaque monkeys anesthetized with different anesthetic agents (ketamine, medetomidine, propofol) and, second, stereo-electroencephalography (sEEG) from 10 epilepsy patients in different wake-sleep stages (wakefulness, NREM, REM). Specifically, we investigated co-activation patterns among brain areas, defined as correlations between local amplitudes of gamma-band activity. We found that resting wakefulness was associated with intermediate levels of gamma-band coupling, indicating neither complete dependence, nor full independence among brain regions. In contrast, loss of consciousness during NREM sleep and propofol anesthesia was associated with excessively correlated brain activity, as indicated by a robust increase of number and strength of positive correlations. However, such excessively correlated brain signals were not observed during REM sleep, and were present only to a limited extent during ketamine anesthesia. This might be related to the fact that, despite suppression of behavioral responsiveness, REM sleep and ketamine anesthesia often involve presence of dream-like conscious experiences. We conclude that hyper-correlated gamma-band activity might be a signature of loss of consciousness common across various manipulations and independent of behavioral responsiveness

Sleep-related epileptic behaviors and non-REM-related parasomnias: Insights from stereo-EEG

During the last decade, many clinical and pathophysiological aspects of sleep-related epileptic and non-epileptic paroxysmal behaviors have been clarified. Advances have been achieved in part through the use of intracerebral recording methods such as stereo-electroencephalography (S-EEG), which has allowed a unique "in vivo" neurophysiological insight into focal epilepsy. Using S-EEG, the local features of physiological and pathological EEG activity in different cortical and subcortical structures have been better defined during the entire sleep-wake spectrum. For example, S-EEG has contributed to clarify the semiology of sleep-related seizures as well as highlight the specific epileptogenic networks involved during ictal activity. Moreover, intracerebral EEG recordings derived from patients with epilepsy have been valuable to study sleep physiology and specific sleep disorders. The occasional co-occurrence of NREM-related parasomnias in epileptic patients undergoing S-EEG investigation has permitted the recordings of such events, highlighting the presence of local electrophysiological dissociated states and clarifying the underlying pathophysiological substrate of such NREM sleep disorders. Based on these recent advances, the authors review and summarize the current and relevant S-EEG literature on sleep-related hypermotor epilepsies and NREM-related parasomnias. Finally, novel data and future research hypothesis will be discussed

Studying functional networks in human brain through intracerebral spontaneous EEG

none6G.Arnulfo; A.Pigorini; M.Massimini; L.Nobili; A.Schenone; M.M. FatoArnulfo, Gabriele; Pigorini, A.; Massimini, M.; Nobili, L.; Schenone, Andrea; Fato, MARCO MASSIM

EEG Responses to TMS Are Sensitive to Changes in the Perturbation Parameters and Repeatable over Time

BACKGROUND: High-density electroencephalography (hd-EEG) combined with transcranial magnetic stimulation (TMS) provides a direct and non-invasive measure of cortical excitability and connectivity in humans and may be employed to track over time pathological alterations, plastic changes and therapy-induced modifications in cortical circuits. However, the diagnostic/monitoring applications of this technique would be limited to the extent that TMS-evoked potentials are either stereotypical (non-sensitive) or random (non-repeatable) responses. Here, we used controlled changes in the stimulation parameters (site, intensity, and angle of stimulation) and repeated longitudinal measurements (same day and one week apart) to evaluate the sensitivity and repeatability of TMS/hd-EEG potentials. METHODOLOGY/PRINCIPAL FINDINGS: In 10 volunteers, we performed 92 single-subject comparisons to evaluate the similarities/differences between pairs of TMS-evoked potentials recorded in the same/different stimulation conditions. For each pairwise comparison, we used non-parametric statistics to calculate a Divergence Index (DI), i.e., the percentage of samples that differed significantly, considering all scalp locations and the entire post-stimulus period. A receiver operating characteristic analysis showed that it was possible to find an optimal DI threshold of 1.67%, yielding 96.7% overall accuracy of TMS/hd-EEG in detecting whether a change in the perturbation parameters occurred or not. CONCLUSIONS/SIGNIFICANCE: These results demonstrate that the EEG responses to TMS essentially reflect deterministic properties of the stimulated neuronal circuits as opposed to stereotypical responses or uncontrolled variability. To the extent that TMS-evoked potentials are sensitive to changes and repeatable over time, they may be employed to detect longitudinal changes in the state of cortical circuits

Global and local complexity of intracranial EEG decreases during NREM sleep

Key to understanding the neuronal basis of consciousness is the characterisation of the neural signatures of changes in level of consciousness during sleep. Here we analysed three measures of dynamical complexity on spontaneous depth electrode recordings from 10 epilepsy patients during wakeful rest and different stages of sleep: (i) Lempel-Ziv complexity, which is derived from how compressible the data are; (ii) amplitude coalition entropy, which measures the variability over time of the set of channels active above a threshold; (iii) synchrony coalition entropy, which measures the variability over time of the set of synchronous channels. When computed across sets of channels that are broadly distributed across multiple brain regions, all 3 measures decreased substantially in all participants during early-night non-rapid eye movement (NREM) sleep. This decrease was partially reversed during late-night NREM sleep, while the measures scored similar to wakeful rest during rapid eye movement (REM) sleep. This global pattern was in almost all cases mirrored at the local level by groups of channels located in a single region. In testing for differences between regions, we found elevated signal complexity in the frontal lobe. These differences could not be attributed solely to changes in spectral power between conditions. Our results provide further evidence that the level of consciousness correlates with neural dynamical complexity

TAAC - TMS Adaptable Auditory Control: A universal tool to mask TMS clicks

Background: Coupling transcranial magnetic stimulation with electroencephalography (TMS-EEG) allows recording the EEG response to a direct, non-invasive cortical perturbation. However, obtaining a genuine TMS- evoked EEG potential requires controlling for several confounds, among which a main source is represented by the auditory evoked potentials (AEPs) associated to the TMS discharge noise (TMS click). This contaminating factor can be in principle prevented by playing a masking noise through earphones. New method: Here we release TMS Adaptable Auditory Control (TAAC), a highly flexible, open-source, Matlab®- based interface that generates in real-time customized masking noises. TAAC creates noises starting from the stimulator-specific TMS click and tailors them to fit the individual, subject-specific click perception by mixing and manipulating the standard noises in both time and frequency domains. Results: We showed that TAAC allows us to provide standard as well as customized noises able to effectively and safely mask the TMS click. Comparison with existing methods: Here, we showcased two customized noises by comparing them to two standard noises previously used in the TMS literature (i.e., a white noise and a noise generated from the stimulator-specific TMS click only). For each, we quantified the Sound Pressure Level (SPL; measured by a Head and Torso Simulator - HATS) required to mask the TMS click in a population of 20 healthy subjects. Both customized noises were effective at safe (according to OSHA and NIOSH safety guidelines) and lower SPLs with respect to standard noises. Conclusions: At odds with previous methods, TAAC allows creating effective and safe masking noises specifically tailored on each TMS device and subject. The combination of TAAC with tools for the real-time visualization of TEPs can help control the influence of auditory confounds also in non-compliant patients. Finally, TAAC is a highly flexible and open-source tool, so it can be further extended to meet different experimental requirements