Search results for "threshold"

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…

Jauna stereoredzes testa izstrāde krustotās un nekrustotās disparitātes novērtēšanai

2017

Darbs uzrakstīts angļu valodā uz 49 lappusēm. Tas satur 47 attēlus, 3 tabulas un atsauces uz 27 literatūras avotiem. Darba mērķis bija izstrādāt jaunu datorizētu stereoredzes testu krustotās un nekrustotās disparitātes novērtēšanai. Lokālās un globālās stereoredzes sliekšņi tika novērtēti pielietojot psihofizikālo trepju metodi. Pētījuma dalībnieku uzdevums bija atpazīt telpiskus attēlus. Stimuliem tika izvēlēti dažādi ekspozīcijas laiki – 5 sekundes (ilgais laiks), 550 ms un 250 ms (īsie laiki). Stereoredzes novērtēšanai papildus tika pielietoti tradicionālie stereotesti – TNO, Titmus tests. Pētījumā piedalījās 37 dalībnieki vecumā no 16 līdz 42 gadiem. Rezultāti tika salīdzināti ņemot vēr…

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 …

Quadriceps and hamstring muscle EMG activity during a football match

2012

Roudi Kalema (2012). Quadriceps and hamstring muscle EMG activity during a football match. Department of Biology of Physical, University of Jyvaskyla. Master’s Thesis in Exercise Physiology. 58 pages. Fatigue represents a reduction in the ability of muscle to generate force and in the context of football, it has been often related with injury. Surface electromyography is a valuable technique for evaluating muscle activation and fatigue but it has never been applied during a football match. The development of washable textile electrodes has opened up possibilities to investigate muscular activity in non-laboratory settings, without skin preparation and wires hanging around the body. It has a…

A fully automatic method for biological target volume segmentation of brain metastases

2016

Leksell Gamma Knife is a mini-invasive technique to obtain a complete destruction of cerebral lesions delivering a single high dose radiation beam. Positron Emission Tomography (PET) imaging is increasingly utilized for radiation treatment planning. Nevertheless, lesion volume delineation in PET datasets is challenging because of the low spatial resolution and high noise level of PET images. Nowadays, the biological target volume (BTV) is manually contoured on PET studies. This procedure is time expensive and operator-dependent. In this article, a fully automatic algorithm for the BTV delineation based on random walks (RW) on graphs is proposed. The results are compared with the outcomes of…

The interplay between cooperativity and diversity in model threshold ensembles

2014

The interplay between cooperativity and diversity is crucial for biological ensembles because single molecule experiments show a significant degree of heterogeneity and also for artificial nanostructures because of the high individual variability characteristic of nanoscale units. We study the cross-effects between cooperativity and diversity in model threshold ensembles composed of individually different units that show a cooperative behaviour. The units are modelled as statistical distributions of parameters (the individual threshold potentials here) characterized by central and width distribution values. The simulations show that the interplay between cooperativity and diversity results …

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…