Cerebellar damage impairs detection of somatosensory input changes. A somatosensory mismatch-negativity study

Several recent studies support the view that the cerebellum's contribution to sensory processing is not limited to movement regulation. In a previous paper (Restuccia D, Valeriani M, Barba C, Le Pera D, Capecci M, Filippini V, Molinari M. Functional changes of the primary somatosensory cortex in patients with unilateral cerebellar lesions. Brain 2001; 124: 757-68) we showed that the cerebellum influences somatosensory input processing at very early stages. The present study was aimed at verifying whether an analogous influence is also exerted at higher levels. For some time it has been known that in the auditory modality a specific event-related potential (ERP), that is, mismatch negativity (MMN), reflects preattentive detection of changes in the incoming stimulus by comparing the new stimulus with sensory memory traces. To test the cerebellar influence on the processing of incoming somatosensory stimuli we first verified whether the electrical stimulation of fingers, according to an 'oddball' paradigm within a stimulus-ignored condition, was able to elicit event-related components specifically linked to the preattentive detection of change. We analysed scalp responses obtained from eight healthy volunteers during frequent and rare electrical stimulation of the first and fifth finger of the left hand, respectively. To ensure that responses to deviant stimuli were due to changes in detection mechanisms, rather than to activation of new afferents, we also analysed responses to rare stimulation alone ('standard-omitted' condition). The 'oddball' stimulation was able to elicit a parieto-occipital extra negativity that was different in scalp distribution and latency from the N140 response to the 'standard-omitted' stimulation. We considered that this response was related to changes in detection mechanisms and labelled it somatosensory mismatch negativity (S-MMN). When the same procedure was applied to six patients with unilateral cerebellar lesions we found that the S-MMN was clearly abnormal after stimulation of the affected hand (ipsilateral to the affected cerebellar hemisphere). Earlier ERPs, as well as ERPs elicited during the 'standard-omitted' condition, were fully normal. Present data indicate that cerebellar processing is involved in preattentive detection of somatosensory input changes. In conclusion, this study demonstrates the reliability of S-MMN recordings and indicates that subjects with cerebellar damage may be impaired in the cortical processing of incoming somatosensory inputs

Influence of biochar additions on the fracture behavior of foamed concrete

The present study concerns the experimental investigation of foamed concretes with 1600 kg/m3 density that incorporate biochar additions in the mix. A series of small notched beams are prepared to determine the fracture energy in CMOD (crack mouth opening displacement) mode and the mechanical properties in terms of flexural and compressive strength. Besides the evaluation of such properties for classical foamed concrete, the influence of the addition of biochar in the lightweight cementitious paste is comparatively investigated. Two different concentrations of biochar are analyzed, namely 2% and 4% of the cement weight, and two different curing conditions are studied, namely in air and in water at controlled temperature for 28 days. The results demonstrate that better fracture behavior are obtained with 2% biochar and air curing conditions. The biochar additions in moderate concentrations (e.g. 2%) seems to make the fracture surface more tortuous, thus justifying the numerical outcomes, and does not impair the flexural strength. Further microstructural investigation is underway to confirm the experimental observations. This research paves the way for a promising construction material that is more environmentally friendly and sustainable than traditional materials used in the building industry

Investigation on the fracture behavior of foamed concrete

Abstract The fracture behavior of lightweight foamed concrete (LWFC) is significantly influenced by microstructural properties, which are ascribed to the arrangement of air bubbles and pores as well as to the presence of different hydration products. In this contribution, an experimental investigation on the fracture behavior of LWFC is performed. Notched beams made of LWFC were tested in three-point bending to determine the fracture energy based on the load-CMOD (Crack Mouth Opening Displacement) curve. The influence of the dry density is explored considering one density for non-structural purposes (equal to 800 kg/m3) and another density for structural applications (1600 kg/m3). Moreover, two curing conditions are considered (air and water). The load-CMOD curves reveal that for lower dry densities the fracture behavior of LWFC is particularly affected by the curing conditions, with better results achieved in air curing conditions, but this influence decreases with higher dry densities. The improved performance in air curing conditions for lower dry densities is also observed in terms of flexural strength, but is not particularly evident for the compressive strength. Micrographs across the crack surface determined via Scanning Electron Microscopy (SEM) are finally presented to analyze the experimental findings and justify the results in terms of microstructural configuration of the specimens

Serum Albumin Is Inversely Associated With Portal Vein Thrombosis in Cirrhosis

We analyzed whether serum albumin is independently associated with portal vein thrombosis (PVT) in liver cirrhosis (LC) and if a biologic plausibility exists. This study was divided into three parts. In part 1 (retrospective analysis), 753 consecutive patients with LC with ultrasound-detected PVT were retrospectively analyzed. In part 2, 112 patients with LC and 56 matched controls were entered in the cross-sectional study. In part 3, 5 patients with cirrhosis were entered in the in vivo study and 4 healthy subjects (HSs) were entered in the in vitro study to explore if albumin may affect platelet activation by modulating oxidative stress. In the 753 patients with LC, the prevalence of PVT was 16.7%; logistic analysis showed that only age (odds ratio [OR], 1.024; P = 0.012) and serum albumin (OR, -0.422; P = 0.0001) significantly predicted patients with PVT. Analyzing the 112 patients with LC and controls, soluble clusters of differentiation (CD)40-ligand (P = 0.0238), soluble Nox2-derived peptide (sNox2-dp; P < 0.0001), and urinary excretion of isoprostanes (P = 0.0078) were higher in patients with LC. In LC, albumin was correlated with sCD4OL (Spearman's rank correlation coefficient [r(s)], -0.33; P < 0.001), sNox2-dp (r(s), -0.57; P < 0.0001), and urinary excretion of isoprostanes (r(s), -0.48; P < 0.0001) levels. The in vivo study showed a progressive decrease in platelet aggregation, sNox2-dp, and urinary 8-iso prostaglandin F2 alpha-III formation 2 hours and 3 days after albumin infusion. Finally, platelet aggregation, sNox2-dp, and isoprostane formation significantly decreased in platelets from HSs incubated with scalar concentrations of albumin. Conclusion: Low serum albumin in LC is associated with PVT, suggesting that albumin could be a modulator of the hemostatic system through interference with mechanisms regulating platelet activation

Study of the CP properties of the Higgs boson in pp->ZH->llbb with the ATLAS experiment at the LHC

The discovery of the Higgs boson in 2012 by the ATLAS and the CMS collaborations at the Large Hadron Collider was pivotal in particle physics. The existence of the Higgs boson, predicted in 1964, is deeply related to the mechanism of electroweak symmetry breaking, and the value of its mass, in conjunction with the value of the mass of the top quark, indicates whether the present electroweak vacuum state of the universe is likely to be stable or not. Given the importance of this new boson, its discovery has been followed by an extensive campaign of measurements of its properties. The analyses of the data collected at sqrt(s) = 7, 8 TeV during the LHC Run1 and at sqrt(s) = 13 TeV during the LHC Run 2 led the ATLAS and the CMS collaborations to observe the leading production modes (gluon gluon fusion, vector boson fusion, production in association with a vector bosons, and production in association with a top quarks), and to observe several decay modes (photon-photon , ZZ, W-W+, tau-tau, bb). By using these datasets, the ATLAS and the CMS collaborations measured the mass of the Higgs boson (mH = 124.97 +/- 0.27 GeV in the latest measurement), its couplings, its spin and its parity, with no significant deviation from the prediction of the Standard Model. The latest observations, in summer 2018, are the production in association with a vector boson (pp -> VH – where V can be either a W or a Z boson) and the decay mode in b-quarks (H -> bb), both guided by the analysis of the pp -> V H(bb) channel. This thesis investigates the possibility to obtain information on the CP properties of the Higgs boson exploiting this channel. The scope is to develop kinematic variables which are sensitive to the CP structure of the HVV coupling. This thesis profits of the analysis developed by the ATLAS collaboration that led to the evidence and observation of pp -> VH and of H -> bb. This work re-uses the event selection of the ATLAS analysis, and it contains two major personal contributions: i) the development of original and alternative tools to model the systematic uncertainties on the backgrounds, which strongly affect this kind of analyses, and ii) the study of the CP structure of the HVV coupling using the pp -> ZH -> llbb channel. In the current pp -> VH(bb) analysis, the signal over background ratio is approximately 2% after a typical event pre-selection. An optimization on the sensitivity is reached thanks to multi variate techniques. As a consequence, any future measurement of the pp -> VH process in the H -> bb channel will depend on the capabilities of the experimental collaborations to model with high accuracy the backgrounds. The estimate of the background is based on Monte Carlo simulations, but their reliability has been verified by only few measurements in the past. The program of the experimental collaborations foresees new accurate measurements of these backgrounds and improvements in the models used in simulations. An additional important aspect is how to include these models and their variations into the pp -> VH(bb) analysis. A natural procedure would be to generate Monte Carlo simulations for all possible variations of a certain background model, and include them in the appropriate statistical treatment of the analysis. The weakness of this option comes from the fact that the simulation of all the needed samples asks for very high computing resources (CPU and disk space). An attractive alternative is to change the shape of the multidimensional distribution of the nominal background model to match the one of an alternative model. This can be done with a multidimensional re-weighting of several kinematic variables, using event-by-event weights. This method is using only the theoretical predictions and it would prevent from simulating the particles-detector interactions (which typically are the most resource demanding) for the alternative models. My original contribution has been the testing of multidimensional reweighting techniques which allows to consistently change the shape of several kinematic variables. This is done by re-using, in an original way, the regression techniques based on gradient boosting algorithms, and demonstrating that it is possible to obtain a good re-weighting of O(10) variables, and that it is a suitable option for future analysis. The second topic, which is the main subject of this work, is to develop variables to study the CP properties of the Higgs boson in pp -> ZH -> llbb. The ATLAS and CMS collaborations already excluded alternative hypothesis for CP++ state of the discovered Higgs boson. On the other side, some models beyond Standard Model, like the Two Higgs Doublet Model, predict the existence of more scalar and pseudoscalar bosons. In these models, if the Higgs potential is not CP symmetric, the lightest mass eigenstate could be a superposition of CP even and odd states, introducing the possibility of non trivial CP structures in the Higgs sector. This option has been already studied by the ATLAS and CMS collaborations, using the kinematic information in the WW and ZZ decays, and more recently, using the production modes. In this context, the study of pp -> VH production mode was proposed in many theoretical work. The effects foreseen by the mixing of CP states are encoded in modifications of the HVV coupling structure, with a mixing of the SM couplingwith a CP-odd tensor. Monte Carlo simulations of events produced by these changes have been used to study the performance of the developed kinematic variables used to investigate the Higgs CP. This thesis represents a first original attempt to study the Higgs CP in this production mode using the data collected by the ATLAS experiment, profiting of the recent observation of the pp -> VH(bb) production

Auditory stimulation enhances thalamic somatosensory high-frequency oscillations in healthy humans: a neurophysiological marker of cross-sensory sensitization?

Electrical stimulation of upper limb nerves evokes a train of high-frequency wavelets (high-frequency oscillations, HFOs) on the human scalp. These HFOs are related to the influence of arousal-promoting structures on somatosensory input processing, and are generated in the primary somatosensory cortex (post-synaptic HFOs) and the terminal tracts of thalamocortical radiations (pre-synaptic HFOs). We previously reported that HFOs do not undergo habituation to repeated stimulations; here, we verified whether HFOs could be modulated by external sensitizing stimuli. We recorded somatosensory evoked potentials (SSEPs) in 15 healthy volunteers before and after sensitization training with an auditory stimulus. Pre-synaptic HFO amplitudes, reflecting somatosensory thalamic/thalamocortical activity, significantly increased after the sensitizing acoustic stimulation, whereas both the low-frequency N20 SSEP component and post-synaptic HFOs were unaffected. Cross-talk between subcortical arousal-related structures is a probable mechanism for the pre-synaptic HFO effect observed in this study. We propose that part of the ascending somatosensory input encoded in HFOs is specifically able to convey sensitized inputs. This preferential involvement in sensitization mechanisms suggests that HFOs play a critical role in the detection of potentially relevant stimuli, and act at very early stages of somatosensory input processing

Discovery Design prodotti e/o servizi per popolazioni del Sud del Mondo

Capó Ivars, D.; Zindato, D.; Restuccia, D.; Di Ciommo, M.; Matteo, R. (2010). Discovery Design prodotti e/o servizi per popolazioni del Sud del Mondo. http://hdl.handle.net/10251/65827.Archivo delegad