Increased liking for a solution is not necessary for the attenuation of neophobia in rats.

Recent evidence suggests that liking and wanting of food rewards can be experimentally dissociated (e.g., Berridge, 1996); this dissociation extends to attenuated neophobia in the present study. Rats tend to eat less of a novel food than a familiar food, a phenomenon called neophobia. The present experiments evaluated whether attenuation of neophobia by prior exposure reflects enhanced liking of the flavor using the Taste Reactivity (TR) test. In Experiment 1, rats given five 10-s TR trials with water or various concentrations of saccharin solution (0.1%, 0.2%, 0.5%) did not show a change in the number of hedonic reactions displayed across trials. However, in a subsequent consumption test from a bottle containing 0.25% saccharin solution, rats with no prior saccharin exposure (group water) consumed less than rats with prior saccharin exposure; that is they displayed neophobia. In Experiment 2, whether rats received five 10-s TR trials with water or 0.5% saccharin solution, they did not display a difference in hedonic reactions to 0.25% saccharin solution in two 5-min TR test trials. These results suggest that the attenuation of neophobia is evidenced as an increase in the tendency to approach a bottle containing the flavored solution (wanting), but not as an enhanced liking of that solution. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of conditioning method and testing method on strength of lithium-induced taste aversion learning.

Here the authors evaluated the effect of the method of conditioning (bottle or intraoral [IO] infusion) on the strength of a flavor-drug association when measured in a standard 1-bottle consumption test or when measured by IO infusion in a taste reactivity test. When tested with the bottle test in Experiment 1, rats conditioned by bottle displayed stronger taste avoidance than those conditioned by IO infusion. When tested for rejection reactions with the taste reactivity test in Experiment 2, rats conditioned by infusion displayed a stronger aversion than did rats conditioned by bottle. The results suggest that when the contextual cues of conditioning are similar at conditioning and testing, a stronger association is evident regardless of the individual specifics of each method. These results may shed light on recent reports that different neural mechanisms are involved in conditioning by active consumption and passive infusion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synchronous machine stability using composite governor and voltage regulator models

Most designers neglect the effect of the governor loop when selecting a suitable voltage regulator transfer function and gain of a turbo-generator. However, with modern fast acting governors, this could lead to unwanted interloop interference and oscillations. This paper investigates the steady state and transient stability limits of such a synchronous turbo-generator using analogue governor and voltage regulator loops similar to those found on large machines (30 – 750 MW). It proposes a design technique which optimizes the gains of the two loops on the basis of maximum steady state stability. Results obtained by measurement on a special micro-machine laboratory simulation are presented. These agree closely with predicted values based upon the well-known two-axis theory of synchronous machines.     

Robust stability of interconnected systems

The concept of generalized block diagonal dominance is used to extend a number of recently developed robust stability results for multivariable systems to large-scale interconnected systems.     

An investigation of subsynchronous resonance by fourier transformation

This paper shows how additional insight into subsynchronous resonance of a series capacitive compensated turbogenerator power system can be obtained by a Fourier analysis of the time domain waveforms. These waveforms are generated by digital computer simulation of the IEEE bench mark model and then sampled, filtered and transformed into the frequency domain which shows up all the mechanical and electrical resonant modes. Different types of disturbances at different load values are used to evaluate their effect on the values of the resonant frequencies.     

A Motorcycle Model for Stability and Control Analysis

The observed dynamic behaviourof motorcycles suggests that interesting andsignificant motions occur that are not currentlyunderstood. The most elaborate modelling exercisecompleted so far has produced results that needconfirmation and extension. The construction of thesemodels necessitates the use of automated methods andone such modelling methodology is described. Theautomated model building platform that was used hereis AutoSim. This code was used to generate a varietyof linear and nonlinear models in symbolic form. Therelatively complex geometry of the steering system andthe front tyre force system is discussed in detail anda new method of checking the self-consistency of themodel is described and exploited. Sample results inthe form of root-locus plots for small perturbationsfrom straight running and cornering equilibrium statesare presented. These are used to reproduce importantfindings from the literature. Conclusions are drawnon the basis of the results presented.     

Amphetamine and morphine produce a conditioned taste and place preference in the house musk shrew (Suncus murinus).

Rats have been shown to avoid consuming a flavor, but prefer a location, previously paired with amphetamine or morphine. A series of 4 experiments evaluated the hedonic properties of amphetamine and morphine in the house musk shrew (Suncus murinus), an insectivore that (unlike rats) is capable of vomiting when exposed to toxins. Unlike rats, amphetamine (20 mg/kg) and morphine (20 mg/kg) produced both a conditioned sucrose (0.3 M) and saccharin (0.1%) preference in shrews (administered intraperitoneally), when measured by both a 1-and a 2-bottle test. At the same dose, both drugs also produced a place preference in shrews. These results suggest that the potential of rewarding drugs to produce taste avoidance may vary on the basis of the ability of the species to vomit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A structured approximation problem with applications to frequencyweighted model reduction

The authors consider the problem of finding necessary and sufficient conditions for the existence of a Q with no more than k poles in the closed left-half plane such that the norm of a certain matrix ⩽1. If solutions exist, a formula for all solutions is given. Special attention is given to the characterization of all optimal solutions. As an application, the frequency weighted optimal Hankel norm model reduction problem is recast as a problem of characterizing every Q which satisfies a certain condition. After reformulation, the model reduction problem is easily solved using the techniques presented in this work     

Normalized H∞ controller reduction with a priorierror bounds

This paper describes an approach to the reduction of controllers for the normalized coprime factor robustness problem as well as the normalized H_∞ problem. It is shown that a relative error approximation of a coprime factor representation of any suboptimal controller leads to a stability guarantee and an upper bound on the performance degradation when the reduced order controller is implemented. When the approximation is performed on the controller generator, guaranteed a priori stability and performance bounds are obtained in terms of the synthesis Riccati equation solutions of the normalized H_∞ control problems     

Vestibular lesions selectively abolish body rotation-induced, but not lithium-induced, conditioned taste aversions (oral rejection responses) in rats.

Pairing a novel taste with provocative vestibular stimulation results in conditioned taste aversions in both rats and humans. Vestibular system involvement in gustatory conditioning was examined in sham-lesioned or labyrinthectomized rats. Three conditioning trials consisted of 30 min access to a saccharin (0.1%) solution followed by 30 min of rotation (70 rpm) or sham rotation. In a taste reactivity test with saccharin, rotated sham-lesioned rats, but not labyrinthectomized rats, exhibited increased oral rejection reactions compared with control rats. When conditioned with lithium chloride, both labyrinthectomized and sham-lesioned rats displayed robust conditioned rejection reactions. The finding that normal vestibular function is necessary in obtaining rotation-induced conditioned taste aversions supports the face and construct validity of a rat model of motion sickness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)