Search results for "threshold"
showing 10 items of 688 documents
<title>Computerized device for critical flicker fusion frequency determination</title>
2003
The critical fusion flicker frequency of the human visual system is the threshold sensitivity for a sine wave-modulated patch of monochromatic flickering light measured as a function of its temporal frequency and average luminance level. The critical flicker fusion frequency changes in different ocular and non-ocular conditions, for example: high-myopia, AMR, glaucoma, schizophrenia, after alcohol intake, fatigue. A computerized test for critical flicker fusion frequency determination was developed. Visual stimuli are two monochromatic LED light sources that are connected to a microcircuit driven by a computer program. The control of the device is realized through the parallel port of the P…
Vitamin A deficiency increases noise susceptibility in guinea pigs.
1990
The effect of vitamin A deficiency in guinea pigs on noise-induced temporary threshold shift (TTS) was evaluated after short (15 min) acoustic overstimulation with a moderate (90 dB) broad-band white noise. Some guinea pigs were fed ad libitum a purified diet deficient in vitamin A (VAD group) until biochemical signs of deficiency occurred. A second, control group (VA group) received the same diet as well as 100 IU vitamin A daily by pharyngeal tube. Cochlear potentials were recorded by special computerized equipment using implanted electrodes. Before acoustic stimulation, a baseline value was determined with a test stimulus [90 dBA (A-filter according to usual DIN instructions)] correspond…
Ascorbic acid reduces noise-induced nitric oxide production in the guinea pig ear.
2008
Objectives: Noise-induced hearing loss can be caused, among other causes, by increased nitric oxide (NO) production in the inner ear leading to nitroactive stress and cell destruction. Some studies in the literature suggest that the degree of hearing loss (HL) could be reduced in an animal model through ascorbic acid supplementation. To identify the effect of ascorbic acid on tissue-dependent NO content in the inner ear of the guinea pig, we determined the local NO production in the organ of Corti and the lateral wall separately 6 hours after noise exposure. Study Design: Prospective animal study in guinea pigs. Methods: Over a period of 7 days, male guinea pigs were supplied with minimum (…
Practical thresholds to distinguish erosive and rill rainfall events
2019
Abstract In this paper, 1017 rainfall events from 2008 to 2017 are used to identify the rainfall threshold that produces upland erosion at the Masse (central Italy) and Sparacia (southern Italy) experimental stations. The rainfall events are classified into three classes: non-erosive, interrill-only and rill. The threshold values for separating as correctly as possible the erosive rains (case I) and the rill rains (case II) are derived solely from the hyetograph. Each threshold value is obtained by imposing that the long-term erosivity of the events above the threshold is equal to the long-term erosivity of all erosive events (case I) or only rill events (case II). The performances of selec…
Feature selection: A multi-objective stochastic optimization approach
2020
The feature subset task can be cast as a multiobjective discrete optimization problem. In this work, we study the search algorithm component of a feature subset selection method. We propose an algorithm based on the threshold accepting method, extended to the multi-objective framework by an appropriate definition of the acceptance rule. The method is used in the task of identifying relevant subsets of features in a Web bot recognition problem, where automated software agents on the Web are identified by analyzing the stream of HTTP requests to a Web server.
More clues about Sensory Impact of Sotolon in Some Flor Sherry Wines
1992
The olfactory impact of sotolon [4,5-dimethyl-3-hydroxy-2(5H)-furanone] in wines was first demonstrated in botrytized wines. In sherry wines it was recently found to occur at concentrations varying from 0 to 500 ppb. The olfactory detection threshold of a sample of purified racemic sotolon was determined to be lower (15 ppb) in white wine than its concentration in most sherries. Its flavor impact in sherries was calculated to be between 1 and 25 OUV. Using MCA of the data obtained from 22 wines (white wines, rancios, Spanish and French sherries) during two tasting sessions by wine professionals, significant positive correlations were found-between the concentration of sotolon and the typica…
Coexistence of quasi-CW and SBS-boosted selfQ-switched pulsing in ytterbium-doped fiber laser with low Q-factor cavity
2020
We report the results of an experimental study of an ytterbium-doped fiber laser with low Q-factor cavity. We demonstrate that the laser operates in two randomly alternating sub-regimes, quasi-CW (QCW) and self-Q-switching (SQS), the latter ignited by stimulated Brillouin scattering (SBS). We show that probability of each sub-regime depends on pump power: QCW dominates slightly above the laser threshold while SQS pulsing prevails at higher pump powers. We also discuss the featuring details of QCW sub-regime and its role in instabilities (jittering) of SBS-boosted SQS pulsing as well as the statistical properties of the latter.
Transient collisionally excited X-ray laser in nickel-like zirconium pumped with the PHELIX laser facility
2004
A transient collisionally excited X-ray laser has been put into operation using the front end of the PHELIX laser system as a pump laser. Strong lasing at 22 nm has been observed in nickel-like zirconium.
Filtering and emission area identification in the Time Resolved Imaging data
2012
Abstract Time Resolved Imaging (TRI) acquisitions allow precise timing analysis of emission spots. Up to date technologies deeply challenge their isolation by hiding the weak ones, under sizing or over sizing visually detectable emission spots and finally by jeopardizing timing resolution. We report on an algorithm based on 1 and 2D signal processing tools which automates the identification of emission sites and optimizes separation between noise and useful signal, even for weak spots surrounding strong emission areas. The application of the algorithm on several sets of data from different types of devices and their results are also discussed.
Étude de la Dynamique des Ondes Spirales à l'Échelle Cellulaire par Modèles Expérimental et Numérique
2012
Among the death due to the cardiac problems, the arrhythmias play a major role, particularly the atrial disorders. This alarming situation attracts an intense research, but it is still limited by the availability of experimental models to reproduce the triggering mechanisms of arrhythmias at the cellular level and extensions of these anomalies. Whether they occur on a healthy or pathological heart, or they are benign or potentially dangerous (risk of sudden death), the arrhythmias constitute an important chapter of the cardiology. This thesis is interested in the studying and modeling of the arrhythmias at a cellular scale. Thus the problems of this thesis can be summarized briefly by the f…