Search results for " Threshold"

Liquid crystalline polymers and elastomers

2002

The results of experiments and theory correlate increasingly well in the investigation of liquid crystalline polymers. Current work focuses on rheology and the behavior of blends of thermotropic LC polymers, due to reemerging economic interest in these materials. Research on liquid crystalline elastomers concentrates on potential applications such as artificial muscles and lasing.

Protective coloration of European vipers throughout the predation sequence

2020

Antipredator adaptations in the form of animal coloration are common and often multifunctional. European vipers (genus Vipera) have a characteristic dorsal zigzag pattern, which has been shown to serve as a warning signal to potential predators. At the same time, it has been suggested to decrease detection risk, and to cause a motion dazzle or flicker-fusion effect during movement. We tested these hypotheses by asking whether (1) the zigzag pattern decreases detection risk and (2) the detection is dependent on the base coloration (grey or brown) or the snake's posture (coiled, basking form or S-shaped, active form). Additionally, (3) we measured the fleeing speed of adders, Vipera berus, an…

Pitch tilt rendering for an 8-DOF driving simulator

2015

International audience; Tilt coordination technique is used for reproducing a sustained linear acceleration in driving simulation by tilting the simulator cabin. Thus a part of gravity is interpreted as a horizontal acceleration. Between the slow rotational motion limited by the rotational perception threshold of semi-circular canals of vestibular system and the fast change of acceleration to render, the design of coupling motions of rotation and translation plays a critical role in the realism of driving simulator. We present here an experiment focusing on longitudinal accelerations rendering with pitch tilt coordination technique. Eight drivers experienced the same accelerations and decel…

Intranasal oxytocin decreases fear generalization in males, but does not modulate discrimination threshold

2021

Background: A previously acquired fear response often spreads to perceptually or conceptually close stimuli or contexts. This process, known as fear generalization, facilitates the avoidance of danger, and dysregulations in this process play an important role in anxiety disorders. Oxytocin (OT) has been shown to modulate fear learning, yet effects on fear generalization remain unknown. Methods: We employed a randomized, placebo-controlled, double-blind, between-subject design during which healthy male participants received either intranasal OT or placebo (PLC) following fear acquisition and before fear generalization with concomitant acquisition of skin conductance responses (SCRs). Twenty-…

Physiological loading during normal daily life and exercise assessed with electromyography

2014

Electromagnetic wave propagation in non-homogeneous waveguides

2015

We investigate an electromagnetic waveguide, having several cylindrical ends. The waveguide is assumed to be empty and to have a perfectly conductive boundary. We study the electromagnetic field, excited in the waveguide in the presence of charges and currents. The field can be described as a solution of the stationary Maxwell system with conductive boundary conditions and “intrinsic” radiation conditions at infinity. We prove the problem to be well-posed. Electromagnetic waves propagation in the waveguide can be described by means of a scattering matrix. We introduce such a matrix for all values of the spectral parameter k in the waveguide continuous spectrum and study its properties. Moreove…

Vizuālās informācijas ietekme uz sāpju slieksni.

2020

Maģistra darbs ir uzrakstīts angļu valodā uz 36 lapam. Tas satur 17 attēlus, 4 tabulas u 82 atsauces. Mērķis: Izpētīt, kā dažādas tematiskās fotogrāfijas modulē sāpju noteikšanas sliekšņus, un novērtētu emocionālās fotogrāfijas izmantojot pašnovērtējuma manekenu metodi (SAM). Metodes: 21 sievietei sāpju noteikšanas sliekšņi tika izmērīti ar pakāpeniski pieaugoša sprieguma padevi dalībnieku apakšdelmiem. Rezultāti: Sāpju noteikšanas sliekšņi tika samazināti ar negatīvām valences fotogrāfijām (attēlojot vardarbību, dzīvnieku un cilvēku uzbrukumus, zaudējumus). Skatoties neitrālās un pozitīvās fotogrāfijas, sāpju noteikšanas sliekšņi neatšķīrās. SAM pozitīvo fotogrāfiju vērtējumi atklāja augst…

Use of electronic nose to determine defect percentage in oils. Comparison with sensory panel results

2010

Abstract An electronic nose based on an array of 6 metal oxide semiconductor sensors was used, jointly with linear discriminant analysis (LDA) and artificial neural network (ANN) method, to classify oils containing the five typical virgin olive oil (VOO) sensory defects (fusty, mouldy, muddy, rancid and winey). For this purpose, these defects, available as single standards of the International Olive Council, were added to refined sunflower oil. According to the LDA models and the ANN method, the defected samples were correctly classified. On the other hand, the electronic nose data was used to predict the defect percentage added to sunflower oil using multiple linear regression models. All …

Temporal resolution and temporal transfer properties: gabaergic and cholinergic mechanisms.

2007

Temporal resolution is a basic property of the visual system and critically depends upon retinal temporal coding properties which are also of importance for directional coding. Whether the temporal coding properties for directional coding derive form inherent properties or critically depend upon the temporal coding mechanisms is unclear. Here, the influence of acetylcholine and GABA upon photopic temporal coding was investigated in goldfish, using flicker stimuli, in a behavioral and an electrophysiological (ERG) approach. The goldfish temporal resolution ability decreased from more than 90% correct choices at 20 Hz flicker frequency to about 65% at 45 Hz flicker frequency with a flicker fu…

Color stimuli perception in presence of light scattering.

2006

Perception of different color contrast stimuli was studied in the presence of light scattering: in a fog chamber in Clermont-Ferrand and in laboratory conditions where light scattering of similar levels was obtained, using different light scattering eye occluders. Blue (shortest wavelength) light is scattered in fog to the greatest extent, causing deterioration of vision quality especially for the monochromatic blue stimuli. However, for the color stimuli presented on a white background, visual acuity in fog for blue Landolt-C optotypes was higher than for red and green optotypes on the white background. The luminance of color Landolt-C optotypes presented on a LCD screen was chosen corresp…