Search results for "Smooth"
showing 10 items of 710 documents
Automatic program for peak detection and deconvolution of multi-overlapped chromatographic signals
2005
Several interlinked algorithms for peak deconvolution by non-linear regression are presented. These procedures, together with the peak detection methods outlined in Part I, have allowed the implementation of an automatic method able to process multi-overlapped signals, requiring little user interaction. A criterion based on the evaluation of the multivariate selectivity of the chromatographic signal is used to auto-select the most efficient deconvolution procedure for each chromatographic situation. In this way, non-optimal local solutions are avoided in cases of high overlap, and short computation times are obtained in situations of high resolution. A new algorithm, fitting both the origin…
Mechanisms involved in the relaxant action of testosterone in the renal artery from male normoglycemic and diabetic rabbits.
2009
Kidney disease is a frequent complication in diabetes, and significant differences have been reported between male and female patients. Our working hypothesis was that diabetes might modify the vascular actions of testosterone in isolated rabbit renal arteries and the mechanisms involved in these actions. Testosterone (10(-8) to 10(-4)M) induced relaxation of precontracted arteries, without significant differences between control and diabetic rabbits. Both in control and diabetic rabbits endothelium removal inhibited testosterone relaxant action. In arteries with endothelium, incubation with indomethacin (10(-5)M), N(G)-nitro-l-arginine (10(-5)M) or tetraethylammonium (10(-5)M) did not modi…
PHOSPHODIESTERASE INHIBITORS PIROXIMONE AND ENOXIMONE INHIBIT PLATELET AGGREGATION IN VIVO AND IN VITRO
1997
The phosphodiesterase type III inhibitors piroximone (PIR) and enoximone (ENO) exert positive inotropic and vasodilating effects in patients with severe heart failure. PIR and ENO raise cyclic AMP levels in cardiac and vascular smooth muscle cells. Platelet activity is also regulated by intracellular levels of cyclic AMP. In this study we have investigated the effects of PIR and ENO on platelet activity in vivo and in vitro. PIR and ENO inhibited ADP induced platelet aggregation in a time- and concentration-dependent manner with IC50-values of 67 +/- 14 mumol/l and 129 +/- 6 mumol/l, respectively. Coincubation of PIR with the adenylate cyclase activator iloprost resulted in a synergistic po…
The development of a hybrid technique employing the boundary element method for thermoelastic stress separation
2000
: This paper presents a development of a hybrid technique employing a boundary element method for determining individual stress components in two-dimensional arbitrarily shaped domains from experimental isopachics only. The procedure consists of a numerical solution of two Poisson equations representing equilibrium for two-dimensional plane-stressed solids with zero body forces. An existing technique is employed for smoothing interior thermoelastic data and enhancing boundary information. The algorithm of stress separation has been implemented with the help of commercial codes. The whole procedure has been tested through a complete post-processing example of thermoelastic stress analysis da…
Quadrature rules for qualocation
2003
Qualocation is a method for the numerical treatment of boundary integral equations on smooth curves which was developed by Chandler, Sloan and Wendland (1988-2000) [1,2]. They showed that the method needs symmetric J–point–quadrature rules on [0, 1] that are exact for a maximum number of 1–periodic functions The existence of 2–point–rules of that type was proven by Chandler and Sloan. For J ∈ {3, 4} such formulas have been calculated numerically in [2]. We show that the functions Gα form a Chebyshev–system on [0, 1/2] for arbitrary indices a and thus prove the existence of such quadrature rules for any J.
Non-periodic Polynomial Splines
2015
In this chapter, we outline the essentials of the splines theory. By themselves, they are of interest for signal processing research. We use the Zak transform to derive an integral representation of polynomial splines on uniform grids. The integral representation facilitated design of different generators of spline spaces and their duals. It provides explicit expressions for interpolating and smoothing splines of any order. In forthcoming chapters, the integral representation of splines will be used for the constructions of efficient subdivision schemes and so also for the design spline-based wavelets and wavelet frames.
Evidence for a modulatory role of cannabinoids on the excitatory NANC neurotransmission in mouse colon
2007
Abstract It is well accepted that endogenous cannabinoids and CB1 receptors are involved in the regulation of smooth muscle contractility and intestinal motility, through a mechanism mainly related to reduction of acetylcholine release from cholinergic nerve endings. Because, few data exist on a possible modulatory action of the cannabinoid agents on the non-adrenergic non-cholinergic (NANC) excitatory and inhibitory neurotransmission, the aim of the present study was to investigate the effects of cannabinoid drugs on the NANC responses elicited by electrical field stimulation (EFS) in the circular muscle of mouse proximal colon. Colonic contractions were monitored as changes in endoluminal…
Endothelin: an endothelium-derived vasoactive peptide and its possible role in the pathogenesis of cerebral vasospasm
1991
The contractile response to endothelin has been examined in cerebral arteries from rats subjected to a prior subarachnoid haemorrhage (SAH) and compared with saline injected controls. Endothelin elicited strong concentration-dependent contraction of rat basilar artery segments. The response was slow in onset and long lasting. The endothelin-induced contraction was much stronger in the SAH compared to control animals. Our findings suggest a role of the peptide in the pathophysiology of cerebral vasospasm.
FILTERING CHAOS: A TECHNIQUE TO ESTIMATE DYNAMICAL AND OBSERVATIONAL NOISE IN NONLINEAR SYSTEMS
2005
Nonlinear dynamical models are frequently used to approximate and predict observed physical, biological and economic systems. Such models will be subject to errors both in the model dynamics, and the observations of the underlying system. In order to improve models, it is necessary to understand the causes of error growth. A complication with chaotic models is that small errors may be amplified by the model dynamics. This paper proposes a technique for estimating levels of both dynamical and observational noise, based on the model drift. The method is demonstrated for a number of models, for cases with both stochastic and nonstochastic dynamical errors. The effect of smoothing or treating …
Stochastic sensitivity of bull and bear states
2021
We study the price dynamics generated by a stochastic version of a Day–Huang type asset market model with heterogenous, interacting market participants. To facilitate the analysis, we introduce a methodology that allows us to assess the consequences of changes in uncertainty on the dynamics of an asset price process close to stable equilibria. In particular, we focus on noise-induced transitions between bull and bear states of the market under additive as well as parametric noise. Our results are obtained by combining the stochastic sensitivity function (SSF) approach, a mixture of analytical and numerical techniques, due to Mil’shtein and Ryashko (1995) with concepts and techniques from th…