117,571 research outputs found
Resting state brain networks: literature review and clinical applications.
No full textThis review focuses on resting-state functional connectivity, a functional MRI technique which allows the study of spontaneous brain activity generated under resting conditions. This approach is useful to explore the brain's functional organization and to examine if it is altered in neurological or psychiatric diseases. Resting-state functional connectivity has revealed a number of networks which are consistently found in healthy subjects and represent specific patterns of synchronous activity. In this review, we examine the behavioral, physiological and neurological evidences relevant to this coherent brain activity and, in particular, to each network. The investigation of functional connectivity appears promising from a clinical perspective, considering the amount of evidence regarding the importance of spontaneous activity and that resting-state paradigms are inherently simple to implement. We also discuss some examples of existing clinical applications, such as in Alzheimer's disease, and emerging possibilities such as in pre-operative mapping and disorders of consciousness
Efficient aerobic oxidation of alcohols in water catalysed by microgel-stabilised metal nanoclusters
No full textNoble metal nanoclusters stabilised by N,N-dimethylacrylamide-based soluble cross-linked polymers (microgels) have been prepared and tested as catalysts in the selective oxidation of secondary alcohols to the corresponding carbonyl compounds with molecular oxygen in water. Pd nanoclusters turned out to be superior catalysts compared with nanoclusters of other noble metals, such as Pt or An, they are efficient (TOF up to 70 h(-1)) and easily recoverable by simple extraction of the reaction product from the aqueous phase
A polymer support with controllable solubility in mutually immiscible solvents
No full textWe report on novel soluble macromolecules displaying rather peculiar solution behaviour, which allows us to gain full control of their partition into three mutually immiscible liquid media: water, dichloromethane and perfluoro(methylcyclohexane); such polymers may be used as soluble supports for reagents or catalysts, yielding supported species whose solubility preference for one out of three liquid phases can be quantitatively and reversibly switched, thereby simplifying separation considerably
First- and second-order phase transitions in electronic excitable units and neural dynamics under global inhibitory feedback
No full text<p>These are experimental time series and video data for an electronic model of neural dynamics consisting of a bi-dimensional array of neon glow lamps, where global inhibition can be simply introduced through a resistor in series with the supply voltage. They are provided to support the replication of the results reported in the associated publication, as well as any further public-domain academic research in the field of neural dynamics, nonlinear electronic circuits, and related aspects, in compliance with the specified license terms and all applicable legal clauses.</p>
<p>The following reference must be cited when using these data:</p>
<p>Minati L, Scarpetta S, Andelic M, Valdes-Sosa PA, Ricci L, de Candia A, First- and second-order phase transitions in electronic excitable units and neural dynamics under global inhibitory feedback, Chaos, Solitons and Fractals 182 (2024) 114701, DOI https://doi.org/10.1016/j.chaos.2024.114701.</p>
<p>L.M. gratefully acknowledges the support of the ``Hundred Talents'' program of the University of Electronic Science and Technology of China, and the support of the ``Excellent Young Scientists Fund Program (Overseas)'' program of the National Natural Science Foundation of China. All experimental activities were self-funded and conducted by L.M. during the period 2020--2021 using own independent assets located in Grigno TN, Italy; the manuscript was later finalized after joining the University of Electronic Science and Technology of China, to which no equipment was transferred. This work has been supported by the Chengdu Science and Technology Bureau Program under Grant 2022GH02-00042-HZ and the CNS program of UESTC No. Y0301902610100201. The authors are grateful to Gabriele Brugnoni of DVE Progettazione Elettronica (Casciago VA, Italy) for essential workshop and manufacturing support.</p>
Effects of abciximab and preprocedural glycemic control in diabetic patients undergoing elective coronary stenting
No full textAm Heart J. 2005 Jun;149(6):1135. Effects of abciximab and preprocedural glycemic control in diabetic patients undergoing elective coronary stenting. De Luca L, De Persio G, Minati M, Iacoboni C, Fedele F. Source Department of Cardiovascular and Respiratory Sciences, La Sapienza University, Rome, Italy. [email protected] Abstract BACKGROUND: In diabetic patients, the combination of abciximab with stenting has been demonstrated to be the standard of care to reduce target vessel revascularization (TVR) and mortality. Moreover, a preprocedural hyperglycemia has been associated with a higher rate of TVR after an elective stent implantation. We sought to evaluate the effects of abciximab and/or preprocedural glycemic control on 30 and 180 days of TVR and on 1-year major adverse cardiac events (MACE-cardiac mortality, TVR, and myocardial infarction) in diabetic patients undergoing elective coronary stenting. METHODS: From January 2002 through May 2003, diabetic patients undergoing elective stenting of de novo coronary artery lesions were randomized to abciximab or placebo infusion. Preprocedural hyperglycemia was defined as fasting plasma glucose >or=126 mg/dL (7.0 mmol/L) immediately before the procedure. RESULTS: A total of 122 consecutive patients with diabetes (62.4 +/- 10.2 years, 80 men) were enrolled in the study. Sixty-nine (56.5%) were randomly assigned to receive abciximab (34 with and 35 without preprocedural hyperglycemia) and 53 (43.5%) to placebo (23 with and 30 without hyperglycemia). Target vessel revascularization was significantly lower in diabetic patients who received abciximab at 30 days (2.9% and 2.8% vs 8.7% and 6.6% in nonabciximab group with or without hyperglycemia, respectively, P < .01) but not at 6 months (31.4% and 26.5% vs 30% and 28.7%, P = NS). Conversely, the cumulative incidence of MACE was significantly higher among diabetic patients with preprocedural hyperglycemia (64.7% and 65.2%) versus diabetic patients with preprocedural glycemic control (37.1% and 40%), treated with or without abciximab, respectively (P < .05). CONCLUSIONS: A preprocedural hyperglycemia is associated with a higher rate of MACE, regardless of the use of abciximab, in diabetic patients undergoing elective coronary stenting. PMID: 15976799 [PubMed - indexed for MEDLINE
Atypical transistor-based chaotic oscillators: Design, realization, and diversity
No full textIn this paper, we show that novel autonomous chaotic oscillators based on one or two bipolar junction transistors and a limited number of passive components can be obtained via random search with suitable heuristics. Chaos is a pervasive occurrence in these circuits, particularly after manual adjustment of a variable resistor placed in series with the supply voltage source. Following this approach, 49 unique circuits generating chaotic signals when physically realized were designed, representing the largest collection of circuits of this kind to date. These circuits are atypical as they do not trivially map onto known topologies or variations thereof. They feature diverse spectra and predominantly anti-persistent monofractal dynamics. Notably, we recurrently found a circuit comprising one resistor, one transistor, two inductors, and one capacitor, which generates a range of attractors depending on the parameter values. We also found a circuit yielding an irregular quantized spike-train resembling some aspects of neural discharge and another one generating a double-scroll attractor, which represent the smallest known transistor-based embodiments of these behaviors. Through three representative examples, we additionally show that diffusive coupling of heterogeneous oscillators of this kind may give rise to complex entrainment, such as lag synchronization with directed information transfer and generalized synchronization. The replicability and reproducibility of the experimental findings are good. Published by AIP Publishing
Estimation of Granger Causality through Artificial Neural Networks: applications to Physiological Systems and Chaotic Electronic Oscillators
No full textOne of the most challenging problems in the study of complex dynamical systems is to find the statistical interdependencies among the system components. Granger causality (GC) represents one of the most employed approaches, based on modeling the system dynamics with a linear vector autoregressive (VAR) model and on evaluating the information flow between two processes in terms of prediction error variances. In its most advanced setting, GC analysis is performed through a state-space (SS) representation of the VAR model that allows to compute both conditional and unconditional forms of GC by solving only one regression problem. While this problem is typically solved through Ordinary Least Square (OLS) estimation, a viable alternative is to use Artificial Neural Networks (ANNs) implemented in a simple structure with one input and one output layer and trained in a way such that the weights matrix corresponds to the matrix of VAR parameters. In this work, we introduce an ANN combined with SS models for the computation of GC. The ANN is trained through the Stochastic Gradient Descent L1 (SGD-L1) algorithm, and a cumulative penalty inspired from penalized regression is applied to the network weights to encourage sparsity. Simulating networks of coupled Gaussian systems, we show how the combination of ANNs and SGD-L1 allows to mitigate the strong reduction in accuracy of OLS identification in settings of low ratio between number of time series points and of VAR parameters. We also report how the performances in GC estimation are influenced by the number of iterations of gradient descent and by the learning rate used for training the ANN. We recommend using some specific combinations for these parameters to optimize the performance of GC estimation. Then, the performances of ANN and OLS are compared in terms of GC magnitude and statistical significance to highlight the potential of the new approach to reconstruct causal coupling strength and network topology even in challenging conditions of data paucity. The results highlight the importance of of a proper selection of regularization parameter which determines the degree of sparsity in the estimated network. Furthermore, we apply the two approaches to real data scenarios, to study the physiological network of brain and peripheral interactions in humans under different conditions of rest and mental stress, and the effects of the newly emerged concept of remote synchronization on the information exchanged in a ring of electronic oscillators. The results highlight how ANNs provide a mesoscopic description of the information exchanged in networks of multiple interacting physiological systems, preserving the most active causal interactions between cardiovascular, respiratory and brain systems. Moreover, ANNs can reconstruct the flow of directed information in a ring of oscillators whose statistical properties can be related to those of physiological networks
FMRI/ERP of musical syntax: comparison of melodies and unstructured note sequences.
No full textTo date, the neural correlates of musical syntax processing have been investigated mainly by means of paradigms in which isolated chords are made incongruent with the harmonic context. Here, we present results obtained contrasting unfamiliar one-part piano melodies with unstructured note sequences, comparable in pitch and rhythm but devoid of any syntactic structure. This paradigm indexes a superset of the cognitive functions involved in processing of harmonic rules. Using functional magnetic resonance imaging, differential activation of a bilateral cortical network comprising the inferior frontal gyrus, superior temporal gyrus and premotor cortex was found. Using event-related potentials, the N2 evoked by each note in melodies was found to have longer latency and a more frontal distribution than that evoked in unstructured sequences
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