Generalized adaptive notch filters with frequency debiasing for tracking of polynomial phase systems

Generalized adaptive notch filters are used for identification/tracking of quasi-periodically varying dynamic systems and can be considered an extension, to the system case, of classical adaptive notch filters. For general patterns of frequency variation the generalized adaptive notch filtering algorithms yield biased frequency estimates. We show that when system frequencies change slowly in a smooth way, the estimation bias can be substantially reduced by means of post-filtering of the frequency estimates. The modified (debiased) algorithm has better tracking capabilities than the original algorithm.     

Expressing the equivalence of non‐isothermal and isothermal heat sterilization processes

Currently, the sterility of heat‐processed food and pharmaceuticals is assessed in terms of an F₀ value, based on the equivalence of the heat treatment to an isothermal process at a reference temperature. This F₀ value, however, has a meaning if, and only if, the inactivation kinetics of the targeted spores (or cells) follow a first‐order relationship and the temperature dependence of the D value, the reciprocal of the rate constant, is log‐linear. There is growing evidence that these conditions are not satisfied by many spores, including those of Clostridium botulinum and vegetative cells. Consequently, a replacement for the F₀ value is proposed in the form of a momentary equivalent time at the reference temperature based on the actual survival pattern of the spores, which need not be log‐linear. This equivalent time can be calculated together with the theoretical survival ratio in real time, thus enabling an operator to monitor the lethality of ongoing industrial heat processes. The concept is demonstrated with published survival data of C. botulinum, for which the Weibullian and log‐logistic models served as primary and secondary models, respectively. The safety factor according to the proposed method is in the number of added minutes of processing, beyond the theoretical time needed to reduce the survival ratio of the targeted spores or cells to a level that would produce practical (or commercial) sterility. Copyright © 2006 Society of Chemical Industry     

A mixture theory for heat conduction in heterogeneous media

A mixture theory based on the ensemble-averaging technique is proposed for studying the thermal behaviour of heterogeneous media. Balance equations with partial heat fluxes and interaction terms are introduced for a two-component medium. Relations between these quantities and the ensemble-averaged (mean) temperatures of separate components are derived. The limits of application of widely used postulates of proportionality of the interaction term of difference in mean temperature of components is discussed. The effective conductivities of components in the mixture and the interaction coefficient are introduced and related to the so-called microstructure functions, which are functions of the microgeometry of the medium and the thermal properties of its components. Examples of the application of the theory to the calculation of the mean properties of a heterogeneous medium are presented.     

Implicit induction in conditional theories

We propose a new procedure for proof by induction in conditional theories where case analysis is simulated by term rewriting. This technique reduces considerably the number of variables of a conjecture to be considered for applying induction schemes. Our procedure is presented as a set of inference rules whose correctness has been formally proved. Moreover, when the axioms are ground convergent and the functions are completely defined, it is possible to apply the system for refuting conjectures. The procedure is even refutationally complete for conditional equations with Boolean preconditions over free constructors. The method is entirely implemented in the proverSPIKE. This system has solved interesting problems in a completely automatic way, that is, without interaction with the user and without ad hoc heuristics. It has also proved the challenging Gilbreath card trick, with only two easy lemmas.Preliminary versions of the results have been presented at the 13th International Joint Conference on Artificial Intelligence, Chambéry (France), 1993 (Bouhoula and Rusinowith, 1993).     

Increased pressor function of central vasopressinergic system in hypertensive renin transgenic rats

OBJECTIVE: Renin transgenic hypertensive rats [TGR(mRen2)27] have increased contents of angiotensin II and arginine vasopressin (AVP) in the cardiovascular brain regions. The aim of the present study was to evaluate the effects of centrally released AVP on the regulation of baseline blood pressure in TGR(mRen2)27 rats and to determine the interaction between AVP and angiotensin II in the central control of blood pressure in this model of hypertension. DESIGN: Three basic series of experiments were performed on 20 TGR(mRen2)27 and 20 Hannover Sprague-Dawley conscious rats, chronically instrumented with lateral cerebral ventricle (LCV) cannulae and femoral artery catheters. In series 1, blood pressure and heart rate were recorded during an LCV infusion of artificial cerebrospinal fluid before and after LCV administration of angiotensin II. In series 2, the effects of an LCV administration of angiotensin 11 (100 ng) on mean arterial pressure and the heart rate were determined during LCV infusion of a selective AVP receptor (V1) antagonist [1-(1-mercapto-4-methylcyclohexaneacetic acid)-8-arginine vasopressin (MeCAAVP) and d(CH2)5[Tyr(Me)2,Ala-NH2(9)]AVP] or a selective angiotensin II type 1 (AT1) receptor antagonist (losartan) or both. In series 3, mean arterial pressure and the heart rate were determined after an LCV injection of either AVP (10 ng) or AVP together with angiotensin II. RESULTS: The LCV infusions of antagonists to V1 and AT1 receptors caused significant comparable decreases in baseline MAP in TGR(mRen2)27 but not in Sprague-Dawley rats. Angiotensin II elicited significant pressor responses, both in TGR(mRen2)27 and in Sprague-Dawley rats. Blockade of V1 receptors significantly reduced the duration and the maximum amplitude of the central pressor response to angiotensin II in TGR(mRen2)27 rats, whereas in Sprague-Dawley rats the maximum pressor effect was not significantly altered. In both strains, the pressor response to angiotensin II was abolished by blockade of AT1 receptors. CONCLUSIONS: The results indicate that the elevated blood pressure in TGR(mRen2)27 rats is partly caused by increased function of the brain angiotensinergic AT1 and vasopressinergic V1 systems. Centrally released AVP is involved in mediation of the pressor effect exerted by centrally applied angiotensin II in TGR(mRen2)27 rats.     

Influence of some lysosomotropic compounds on calcium ion desorption process from liposome membrane

The effect of a group of model lysosomotropic compounds on the process of Ca2+ ion desorption from lecithin liposome membranes was studied. The compounds studied were: hydrochlorides of fatty acids 2-dimethylaminoethyl esters (DM-n) for n = 9, 11, 13 and 15 carbon atoms in the fatty acid alkyl chain and methochloride of 2-dimethylaminoethyl laurate (DMS-11). It was found that all the compounds studied caused increased desorption with increasing concentration of the compound. Most effective was the quaternary ammonium salt, DMS-11. Moreover, it was found that the process of Ca2+ desorption from the membrane depended on pH of the medium. Compound DM-11 was more active at pH 8 than at pH 5. The action of DM-n compounds depended on the alkyl chain length, DM-11 and DM-13 being the most active. Apparently free amines penetrate the phospholipid membranes and incorporate into its hydrophobic core causing structural deformations. Hydrochlorides of fatty acids and the quaternary ammonium salt induce desorption of calcium ions mostly as a result of competitive electrostatic interactions. By quantum chemistry, PM3 method, and methods of molecular modelling we established the higher hydrophilicity of the polar head of DM-n series with respect to the polar head of the DMS-n compounds. DM-n compounds possess both acceptor and donor properties for hydrogen bonding while DMS-n are instrumental as acceptors only. It should be noted, that the results obtained in this paper for model membranes are in accordance with those for biological ones.     

CS modality transfer of two-way avoidance in rats with central and basolateral amygdala lesions

Post-lesion acquisition of two-way avoidance and subsequent transfer to two warning signals (conditioned stimulus, CS) of different modality were investigated in 60 rats. In Experiment I the animals were originally trained with less salient (darkness) CS, then transferred to more salient compound (darkness and white noise), and finally to white noise CS. The opposite arrangement of the conditioned stimuli (CSi) during the subsequent stages was employed in Experiment II. In control animals, avoidance acquisition was faster and the intertrial responding (ITR) rate lower with the auditory than with the visual CS. Lesioned rats learned avoidance responses more slowly, independently of CS modality. The transfer to other CSi revealed dramatic between-group difference in the level and consistency of avoidance response, shuttle-box latencies and ITR rate. In control animals, transfer to more salient CSi enhanced avoidance performance, whereas change to less salient CS decreased it. Rather small changes in shuttle-box performance and consistency of avoidance response due to CS modality were seen in rats with the basolateral lesions. In contrast, central nucleus injury caused a strong deterioration in the avoidance transfer, especially when the visual CS followed the acoustic one. The results indicate differential involvement of the basolateral and central amygdala nuclei in stimulus-processing mechanisms of instrumental defensive behavior.