Search results for "Diagonal"
showing 10 items of 124 documents
Nucleus incertus contribution to hippocampal theta rhythm generation.
2006
The hippocampal theta rhythm is generated by the pacemaker activity of the medial septum-diagonal band of Broca (MS/DBB) neurons. These nuclei are influenced by brainstem structures that modulate the theta rhythm. The aim of the present work is to determine whether the nucleus incertus (NI), which has important anatomical connections with the MS/DBB, contributes to the hippocampal theta rhythm generation in rats. Hippocampal field activity was recorded in urethane-anaesthetized rats. Electrical stimulation of the NI not only evoked theta rhythm in the hippocampus, but also decreased the amplitude of delta waves. Unit recordings in the NI revealed either a non-rhythm discharge pattern in mos…
Anatomical evidence for a ponto-septal pathway via the nucleus incertus in the rat.
2008
Abstract Hippocampal theta activity is involved in sensory–motor integration and constitutes a functional basis for mnemonic functions. The medial septum–diagonal band of Broca (MS/DBv) is a key structure as pacemaker of the oscillation. In addition, some brainstem reticular structures are crucial for the activation of MS/DBv. Specifically, the nucleus reticularis pontis oralis (RPO) is considered the most effective pontine site for eliciting theta rhythm. Nevertheless, its connection with the MS/DBv is not direct. A previous study by our group pointed out that the nucleus incertus (NI) could be considered as a relay in this multisynaptic pathway. From this study, the stimulation of RPO inc…
Changes in brain oxidative metabolism induced by inhibitory avoidance learning and acute administration of amitriptyline
2007
The effects of antidepressant drugs on memory have been somewhat ignored, having been considered a mere side effect of these compounds. However, the memory impairment caused by several antidepressants could be considered to form part of their therapeutic effects. Amitriptyline is currently one of the most prescribed tricyclic antidepressants, and exerts marked anticholinergic and antihistaminergic effects. In this study, we evaluated the effects of inhibitory avoidance (IA) learning and acute administration of amitriptyline on brain oxidative metabolism. Brain oxidative metabolism was measured in several limbic regions using cytochrome oxidase (CO) quantitative histochemistry. Amitriptyline…
Definition of diagonal Poisson's ratio and elastic modulus for infill masonry walls
2014
The prediction of the response of infilled frames through the simplified approach of substituting the infill with an equivalent pin-jointed strut is treated. In this framework the results of an experimental study for the mechanical characterization of different types of masonry infills having the aim of estimating strength, Young modulus and Poisson's ratio are presented. Four types of masonry were investigated and subjected to ordinary compressive tests orthogonally to the mortar beds and along the directions of the mortar beds. The experimental campaign confirmed the possibility of using an orthotropic plate model for prediction of the Poisson's ratio and Young modulus along the diagonal …
Infilled frames: developments in the evaluation of the stiffening effect of infills
2003
In order to consider the modified seismic response of framed structures in the presence of masonry infills, proper models have to be formulated. Because of the complexity of the problem, a careful definition of a diagonal pin-jointed strut, able to represent the horizontal force-interstorey displacement cyclic law of the actual infill, may be a solution. In this connection the present paper shows a generalized criterion for the determination of the ideal cross-section of the strut mentioned before. The procedure is based on the equivalence between the lateral stiffness of the actual infilled frame scheme during the conventional elastic stage of the response and the lateral stiffness of the …
Functional Differential and Difference Equations with Applications
2012
and Applied Analysis 3 solutions to a class of nonlocal boundary value problems for linear homogeneous secondorder functional differential equations with piecewise constant arguments are obtained. The last but not the least, this issue features a number of publications that report recent progress in the analysis of problems arising in various applications. In particular, dynamics of delayed neural network models consisting of two neurons with inertial coupling were studied, properties of a stochastic delay logistic model under regime switching were explored, and analysis of the permanence and extinction of a single species with contraception and feedback controls was conducted. Other applie…
Retrofit of External Beam-Column Concrete Joints with Diagonally Crossed Reinforcement: Experimental and Analytical Investigations
2022
AbstractExperimental research was carried out regarding the flexural behavior under cyclic reversal loading of six full-scale external beam-column concrete joints cast with plain concrete in the pr...
Diagonalization of large matrices: a new parallel algorithm.
2015
On the basis of a dressed matrices formalism, a new algorithm has been devised for obtaining the lowest eigenvalue and the corresponding eigenvector of large real symmetric matrices. Given an N × N matrix, the proposed algorithm consists in the diagonalization of (N - 1)2 × 2 dressed matrices. Both sequential and parallel versions of the proposed algorithm have been implemented. Tests have been performed on a Hilbert matrix, and the results show that this algorithm is up 340 times faster than the corresponding LAPACK routine for N = 10(4) and about 10% faster than the Davidson method. The parallel MPI version has been tested using up to 512 nodes. The speed-up for a N = 10(6) matrix is fair…
Reducing the bandwidth of a sparse matrix with tabu search
2001
The bandwidth of a matrix { } ij a A = is defined as the maximum absolute difference between i and j for which 0 ≠ ij a . The problem of reducing the bandwidth of a matrix consists of finding a permutation of the rows and columns that keeps the nonzero elements in a band that is as close as possible to the main diagonal of the matrix. This NP-complete problem can also be formulated as a labeling of vertices on a graph, where edges are the nonzero elements of the corresponding symmetrical matrix. Many bandwidth reduction algorithms have been developed since the 1960s and applied to structural engineering, fluid dynamics and network analysis. For the most part, these procedures do not incorpo…
Robust and Efficient IMEX Schemes for Option Pricing under Jump-Diffusion Models
2013
We propose families of IMEX time discretization schemes for the partial integro-differential equation derived for the pricing of options under a jump diffusion process. The schemes include the families of IMEX-midpoint, IMEXCNAB and IMEX-BDF2 schemes. Each family is defined by a convex parameter c ∈ [0, 1], which divides the zeroth-order term due to the jumps between the implicit and explicit part in the time discretization. These IMEX schemes lead to tridiagonal systems, which can be solved extremely efficiently. The schemes are studied through Fourier stability analysis and numerical experiments. It is found that, under suitable assumptions and time step restrictions, the IMEX-midpoint fa…