Search results for " Conduction"
showing 10 items of 373 documents
Electrophysiology of sensory neuropathies
1995
In sensory neuropathy maximal conduction velocity is a crude measure. Variations up to 10 m/s have to be considered normal. The relation to clinical impairment is poor in either axonal/neuronal lesions or demyelination as indicated by a small normal latency and a delayed broad polyphasic nerve action potential (NAP), respectively. Conduction block evaluated on NAP changes has not yet been established. Mild disorder of impulse conduction may be disclosed by evaluating a) conduction along long nerve segments studying the H-reflex or SSEP, b) late components of the averaged NAP which make > 10% of the main deflection, c) velocities of slow conducting fibers utilizing the collision technique or…
Efficient High-Order Iterative Methods for Solving Nonlinear Systems and Their Application on Heat Conduction Problems
2017
[EN] For solving nonlinear systems of big size, such as those obtained by applying finite differences for approximating the solution of diffusion problem and heat conduction equations, three-step iterative methods with eighth-order local convergence are presented. The computational efficiency of the new methods is compared with those of some known ones, obtaining good conclusions, due to the particular structure of the iterative expression of the proposed methods. Numerical comparisons are made with the same existing methods, on standard nonlinear systems and a nonlinear one-dimensional heat conduction equation by transforming it in a nonlinear system by using finite differences. From these…
Dendritic Ih selectively blocks temporal summation of unsynchronized distal inputs in CA1 pyramidal neurons.
2004
The active dendritic conductances shape the input-output properties of many principal neurons in different brain regions, and the various ways in which they regulate neuronal excitability need to be investigated to better understand their functional consequences. Using a realistic model of a hippocampal CA1 pyramidal neuron, we show a major role for the hyperpolarization-activated current, I-h, in regulating the spike probability of a neuron when independent synaptic inputs are activated with different degrees of synchronization and at different distances from the soma. The results allowed us to make the experimentally testable prediction that the I-h in these neurons is needed to reduce ne…
Heat transfer by using TiO2 nanofluids
2021
Abstract In the last decades, nanofluids have been proposed as thermo-vector fluids thanks to their interesting properties of thermal conduction and stability, which allow interesting performance in heat transfer applications. Consequently, different studies on the thermal properties, the potential benefits, and the possible applications of nanofluids appeared in the scientific literature. This chapter deals with heat transfer characteristics of TiO2 nanofluids, which nowadays appear to be almost ready for practical applications. Particular attention has been given to the preparation, the characterization, and the effects of different parameters on heat transfer. Moreover, challenges and op…
Asymmetric nanopore rectification for ion pumping, electrical power generation, and information processing applications
2011
Single-track, asymmetric nanopores can currently be functionalised with a spatially inhomogeneous distribution of fixed charges and a variety of pore tip shapes. Optimising the asymmetric nanopore characteristics is crucial for practical applications in nanofluidics. We have addressed here this question for three cases based on different input/output chemical and electrical signals: (i) ion pumping up a concentration gradient by means of a periodic, time-dependent bias potential, (ii) information processing with a single nanopore acting as the nanofluidic diode of a logic gate, and (iii) electrical energy harvesting using a nanopore that separates two solutions of different salt concentrati…
Mapping of local conductivity variations on fragile nanopillar arrays by scanning conductive torsion mode microscopy.
2010
A gentle method that combines torsion mode topography imaging with conductive scanning force microscopy is presented. By applying an electrical bias voltage between tip and sample surface, changes in the local sample conductivity can be mapped. The topography and local conductivity variations on fragile free-standing nanopillar arrays were investigated. These samples were fabricated by an anodized aluminum oxide template process using a thermally cross-linked triphenylamine-derivate semicondcutor. The nanoscale characterization method is shown to be nondestructive. Individual nanopillars were clearly resolved in topography and current images that were recorded simultaneously. Local current−…
Electronic transport measurements and Raman spectroscopy on carbon nanotube devices
2009
An individual single wall carbon nanotube (SWCNT) device has been fabricated and measured using both low temperature transport and Raman measurements. With these mutually independent methods we can study the correlation between the techniques on semiconducting or metallic behavior of the tube. Furthermore, we study the structure of the nanotube by probing Raman measurements at different spots along the tube axis.
Quantum Transport and Current Distribution at Radio Frequency in Multiwall Carbon Nanotubes
2012
Multiwall carbon nanotubes represent a low-dimensional material that could serve as building blocks for future carbon-based nanoelectronics. The understanding of the electromagnetic performances at radio frequency of these materials for use in nanointerconnects is strictly related to the analysis of their transport properties as function of the working conditions. In this paper, we present an explicit expression of the conducting channels as function of diameter, temperature, doping, and supply voltage for both metallic and semiconducting carbon nanotubes. The proposed formula is based on the Dirac cone approximation of the conducting band energy of graphene nearby the Fermi points, combine…
Resonance properties of different neuronal populations in the immature mouse neocortex
2012
In vivo recordings in the immature neocortex revealed spontaneous and sensory-driven oscillatory activity from delta (0.5-4 Hz) to gamma (30-100 Hz) frequencies. In order to investigate whether the resonance properties of distinct neuronal populations in the immature neocortex contribute to these network oscillations, we performed whole-cell patch-clamp recordings from visually identified neurons in tangential and coronal neocortical slices from postnatal day (P)0-P7 C57Bl/6 mice. Subthreshold resonance was analysed by sinusoidal current injection of varying frequency. All Cajal-Retzius cells showed subthreshold resonance, with an average frequency of 2.6 ± 0.1 Hz (n = 60), which was massiv…
Vulnerability of different nerves to intrafascicular injection by different needle types and at different approach angles: a mathematical model
2019
Background and objectivesWe assume that intrafascicular spread of a solution can only occur if a large enough portion of the distal needle orifice is placed inside the fascicle. Our aim is to present and evaluate a mathematical model that can calculate the theoretical vulnerability of fascicles, analyzing the degree of occupancy of the needle orifice in fascicular tissue by performing simulations of multiple positions that a needle orifice can take inside a cross-sectional nerve area.MethodsWe superimposed microscopic images of two routinely used nerve block needles (22-gauge, 15° needle and 22-gauge, 30° needle) over the microscopic images of cross-sections of four nerve types photographed…