Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Differential Threshold”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 487 records · Page 27Linked to original sources
PubMed1984

Effects of previous exercise on the ventilatory determination of the aerobic threshold.

To study the effects of previous submaximal exercise on the ventilatory determination of the Aerobic Threshold (AeT), 16 men were subjected to three maximal exercise tests (standard test = ST, retest = RT, and test with previous exercise = TPE ) on a cycle ergometer. The protocol for the three tests consisted of 3 min pedalling against 25 W, followed by increments of 25 W every minute until volitional fatigue. TPE was preceded by 10 min cycling at a power output corresponding to the AeT as determined in ST, followed by a recovery period pedalling against 25 W until VO2 returned to values consistent with the initial VO2 response to 25 W. AeT was determined from the gas exchange curves (ventilatory equivalent for O2, fraction of expired O2, excess of VCO2, ventilation, and respiratory gas exchange ratio) printed every 30 s. The results showed good ST X RT reliability (r = 0.89). TPE showed significantly higher AeT values (2.548 +/- 0.44 1 X min-1) when compared with ST (2.049 +/- 0.331 X min-1) and RT (2.083 +/- 0.30 1 X min-1). There were no significant differences for the sub-threshold respiratory gas exchange ratios among the trials. The sub-threshold VO2 response showed significantly higher values for TPE at power outputs above 50 W. It was concluded that the performance of previous exercise can increase the value for the ventilatory determination of the AeT due to a faster sub-threshold VO2 response.

Adult↗
PubMed1980

Mouse-killing in rats induces a naloxone-blockable increase in nociceptive threshold.

Mouse-killing behaviour in rats increased the nociceptive threshold for paw licking, as measured in the hot-plate test. This effect was prevented by the opiate antagonist naloxone, which, on the other hand, had no influence on mouse-killing behavior per se. It is concluded that opioid mechanisms may be involved in changes of nociceptive threshold associated with aggressive behavior.

Aggression↗
PubMed1996

Mechanisms underlying the detection of increments in parafoveal retina.

It is well established that the spectral sensitivity under photopic conditions varies across the human retina. We investigate the mechanisms underlying these spectral changes. Through the use of color appearance, flicker sensitivity, additivity, discrimination at threshold and modeling, we show that the changes in spectral sensitivity on a photopic white background across parafoveal retina are consistent with shifts in cone weightings to (L-M) and (M-L) chromatic channels. This two channel model, developed to account for foveal spectral sensitivity curves (Sperling & Harwerth, 1971 Science, 172, 180-184), provides a better description of parafoveal data than both a single color channel upper envelope model (comprised of a single red-green opponent channel and an achromatic mechanism) and a vector model (combining a red-green opponent channel with an achromatic component). Thus while the two channel model ([L-M] and [M-L]) of foveal color vision is generalizable to the parafovea, simple models with a unitary red/green process are not. Although the two channel model can accurately fit parafoveal spectral sensitivity curves without it, a small contribution from a luminance mechanism might improve the ability of the two channel model to account for threshold discrimination and additivity data.

Color Perception↗
PubMed1994

Life-span of Drosophila melanogaster in highly oxygenated atmospheres.

The life-span of Drosophila melanogaster males kept for their entire life in atmospheres of differing O2 concentration (21%, 30%, 40%) was measured. The life-span decreased linearly with the increase in O2 proportion. In order to test the rate of living and the threshold theories of ageing, Drosophila melanogaster males were kept for 15 days in a given atmosphere and from day 16 on in another one. The life-spans observed in these alternate conditions were very close to the values predicted by the rate of living theory and are thus not compatible with the threshold theory.

Animals↗
PubMed2000

An anatomically based frequency-place map for the mouse cochlea.

An anatomically based frequency-place map was created for the mouse using C57BL/CBA F1 hybrids by matching noise-induced lesions in the organ of Corti with permanent hearing losses as determined by auditory brainstem response (ABR) thresholds. Twenty-six mice developed 'notched' ABR threshold shifts after exposure to an octave band of noise with a center frequency of 2 kHz at 120 dB SPL for 24 h, 4 kHz at 110 dB SPL for 4 h or 8 kHz at 100 dB SPL for 1 or 2 h. ABR thresholds were determined at several intervals post-exposure until thresholds stabilized (14-27 days). Once thresholds had stabilized, the mice were killed and their cochleas were prepared for phase-contrast microscopic examination as plastic-embedded flat preparations. Hair cell loss, stereocilia damage, and myelinated nerve fiber degeneration as a function of percentage distance from the cochlear apex were determined. Frequency-position matches could be made for 22 of the 26 mice by correlating areas of hair cell loss/stereocilia damage with permanent changes in ABR thresholds. These frequency-position data were fitted with the equation: % Distance from apex=56.6 log (f(Hz))-179.1; r(2)=0.810. This frequency-place function agrees well with Ehret's (1975) theoretical function based on critical bands and masked auditory thresholds.

Animals↗
PubMed1984

Discrimination of velocities and mechanisms of motion perception.

In a first experiment, velocity discrimination thresholds were measured in twenty-one experimental conditions by presentation of successive pairs of standard/comparison motions of a single spot target. Exposure times between 300 to 900 ms did not affect velocity discrimination. However, very slow velocity increased discrimination thresholds. Velocity discrimination is improved by the presence of stationary references and decreased by eccentricity. At slow velocities, in the absence of a motion phase, a discrete mode of presentation of the translation leads to higher discrimination thresholds than those observed with the continuous and stop-go-stop modes of the same translation. In a second experiment, it was shown that for shorter exposure time (100 ms), discrimination thresholds are much higher for the discrete mode. It is concluded that at long exposure time, velocity discrimination thresholds are essentially independent of the presence of a motion phase.

Differential Threshold↗
PubMed2004

Statistical modeling of sequencing errors in SAGE libraries.

MOTIVATION: Sequencing errors may bias the gene expression measurements made by Serial Analysis of Gene Expression (SAGE). They may introduce non-existent tags at low abundance and decrease the real abundance of other tags. These effects are increased in the longer tags generated in LongSAGE libraries. Current sequencing technology generates quite accurate estimates of sequencing error rates. Here we make use of the sequence neighborhood of SAGE tags and error estimates from the base-calling software to correct for such errors. RESULTS: We introduce a statistical model for the propagation of sequencing errors in SAGE and suggest an Expectation-Maximization (EM) algorithm to correct for them given observed sequences in a library and base-calling error estimates. We tested our method using simulated and experimental SAGE libraries. When comparing SAGE libraries, we found that sequencing errors can introduce considerable bias. High abundance tags may be falsely called as significantly differentially expressed, especially when comparing libraries with different levels of sequencing errors and/or of different size. Truly, differentially expressed tags have decreased significance as 'true'-tag counts are generally underestimated. This may alter if tags near the threshold of differential expression are called significant. Moreover, the number of different transcripts present in a library is overestimated as false tags are introduced at low abundance. Our correction method adjusts the tag counts to be closer to the true counts and is able to partly correct for biases introduced by sequencing errors. AVAILABILITY: An implementation using R is distributed as an R package. An online version is available at http://tagcalling.mbgproject.org

Algorithms↗
PubMedDate not supplied

Amplitude and pulse rate difference limens for electrical stimulation of the cochlea following graded degeneration of the auditory nerve.

Experimentally deafened cats with differing populations of residual spiral ganglion cells were implanted with cochlear electrodes and were electrically stimulated. They were conditioned to respond to changes in electrical pulse rate and amplitude, and both electrical pulse rate and amplitude difference limens were determined. It was found that although there were some variations in difference limens between animals, these showed no correlation with residual cell populations over the range 8-44%.

Acoustic Stimulation↗