Search results for "Stochastic Proce"
showing 10 items of 349 documents
Coupled stochastic dynamics of magnetic moment and anisotropy axis of a magnetic nanoparticle
2012
An algorithm is developed for numerical simulation of coupled stochastic dynamics of magnetic moment and magnetic anisotropy axis of a nanoparticle. Time-correlation functions of the magnetic moment and its components longitudinal and transverse to the magnetic anisotropy axis are calculated by averaging along the stochastic trajectory. The longitudinal and transverse relaxation times are found by fitting the time correlation functions. Existing theoretical relations derived by the effective field approach in the limit of small fields are confirmed. The time-correlation functions of magnetic moments of nanoparticles in dependence on their properties are calculated numerically for arbitrary …
Structure of rat behavior in hole-board: I) multivariate analysis of response to anxiety
2008
Aim of present paper was to carry out an analysis of rat behavior in hole-board following different multivariate approaches. Thirty male Wistar rats were observed in a hole-board apparatus and their behavior recorded for 10 min through a digital videocamera for a following frame-by-frame analysis. Both descriptive and multivariate analyses were used. Descriptive analysis showed that roughly 85% of the whole behavioral structure encompassed six patterns appearing during the first minute of observation: walking, climbing, rearing, immobile-sniffing, edge-sniff and head-dip. As to multivariate approach, cluster analysis showed three main dyadic associations: [edge-sniff/head-dip], [walking/cli…
Multivariate analysis of the modifications induced by an environmental acoustic cue on rat exploratory behavior.
2007
The aim of the present paper is to study by means of a multivariate analysis the modifications induced by an environmental acoustic cue on the structure of rat exploratory behavior. Adult male Wistar rats were observed during the exploration of a soundproof observation box. Each rat was acoustically stimulated after 150 s from the beginning of the experimental session, lasting 300 s, and recorded through a digital videocamera. A frame by frame analysis was thereafter carried out using a professional video-recording system. Thirteen behavioral patterns were selected: immobility, immobile-sniffing, walking, rearing, climbing, chewing, paw-licking, face-grooming, body-grooming, head-turning, t…
Effects of 7-OH-DPAT and U 99194 on the behavioral response to hot plate test, in rats
2005
Aim of present study was to investigate in male Wistar rats, whether behavioral response to hot plate test application could be influenced by systemic administration of 7-OH-DPAT, a dopaminergic (DA) D3 versus D2 receptor agonist, or U 99194, a DA D3 versus D2 receptor antagonist. Each trial lasted no more than 10 s and the whole experimental session lasted 120 min. Animal behavior was recorded by means of a digital videocamera and later, frame by frame examined using a professional videorecorder. Latency of each behavioral pattern, characterizing the response, was analysed, showing significant changes only with U 99194. A multivariate cluster analysis indicated the presence of three main b…
A stochastic approach for automatic registration and fusion of left atrial electroanatomic maps with 3D CT anatomical images.
2007
The integration of electroanatomic maps with highly resolved computed tomography cardiac images plays an important role in the successful planning of the ablation procedure of arrhythmias. In this paper, we present and validate a fully-automated strategy for the registration and fusion of sparse, atrial endocardial electroanatomic maps (CARTO maps) with detailed left atrial (LA) anatomical reconstructions segmented from a pre-procedural MDCT scan. Registration is accomplished by a parameterized geometric transformation of the CARTO points and by a stochastic search of the best parameter set which minimizes the misalignment between transformed CARTO points and the LA surface. The subsequent …
Prediction of leukocyte counts during paediatric acute lymphoblastic leukaemia maintenance therapy
2019
Maintenance chemotherapy with oral 6-mercaptopurine and methotrexate remains a cornerstone of modern therapy for acute lymphoblastic leukaemia. The dosage and intensity of therapy are based on surrogate markers such as peripheral blood leukocyte and neutrophil counts. Dosage based leukocyte count predictions could provide support for dosage decisions clinicians face trying to find and maintain an appropriate dosage for the individual patient. We present two Bayesian nonlinear state space models for predicting patient leukocyte counts during the maintenance therapy. The models simplify some aspects of previously proposed models but allow for some extra flexibility. Our second model is an ext…
Structure of rat behavior in hole-board: II) multivariate analysis of modifications induced by diazepam.
2009
In our previous study we suggested that multivariate analysis could improve hole-board test reliability providing a more useful tool to determine behavioral effects of anxiolytic drugs. To support this hypothesis, a multivariate analysis of rat behavior in hole-board, following administration of the reference anxiolytic drug diazepam, was carried out. Four groups, each composed of thirty male Wistar rats, were used: one saline and three diazepam injected (0.25, 0.5 and 2 mg/kg IP). Rat behavior was recorded for 10 min through a digital videocamera. Descriptive and multivariate analyses were carried out. In all groups, more than 80% of whole behavioral structure encompassed walking, climbing…
Tool replacement with adaptive control in a non-stationary non-periodic stochastic process
1991
Abstract The problem of optimum tool replacement is studied in the case in which tool performance is characterized by progressive decay over time following stochastic laws. A control system is assumed which detects, continuously or at fixed intervals, the service state of the tool. Assuming that the service state of the tool affects the marginal cost of production, the latter is used in order to minimize the unit production cost for an unlimited production horizon. The replacement policy proposed is able to update itself in process by means of an iterative procedure which converges to a conditioned optimum. The effectiveness of such a policy is demonstrated analytically, and illustrative ex…
New approach to delay-dependent H∞ control for continuous-time Markovian jump systems with time-varying delay and deficient transition descriptions
2015
Abstract This paper proposes an input–output (IO) approach to the delay-dependent stability analysis and H ∞ controller synthesis for a class of continuous-time Markovian jump linear systems (MJLSs). The concerned systems are with a time-varying delay in the state and deficient mode information in the Markov stochastic process, which simultaneously involves the exactly known, partially unknown and uncertain transition rates. It is first shown that the original system with time-varying delay can be reformulated by a new IO model through a process of two-term approximation and the stability problem of the original system can be transformed into the scaled small gain (SSG) problem of the IO mo…
Stationary and non-stationary stochastic response of linear fractional viscoelastic systems
2012
Abstract A method is presented to compute the stochastic response of single-degree-of-freedom (SDOF) structural systems with fractional derivative damping, subjected to stationary and non-stationary inputs. Based on a few manipulations involving an appropriate change of variable and a discretization of the fractional derivative operator, the equation of motion is reverted to a set of coupled linear equations involving additional degrees of freedom, the number of which depends on the discretization of the fractional derivative operator. As a result of the proposed variable transformation and discretization, the stochastic analysis becomes very straightforward and simple since, based on stand…