Showing papers on "Latency (engineering) published in 1984"

Abnormalities of proximal conduction in acute idiopathic polyneuritis: comparison of short latency evoked potentials and F-waves.

Abstract: Motor and sensory conduction studies, F-wave latency, and the latency of evoked potentials from the brachial plexus and cervical spine in response to median nerve stimulation were examined in 17 patients with acute idiopathic polyneuropathy. Short latency evoked potentials provided a higher yield of evidence of abnormalities of proximal conduction than did the F-wave latency. Both methods of studying conduction in the proximal segments of a peripheral nerve may be normal, however, in a small number of patients who have significant pathological lesions.

Herpes simplex virus latency in isolated human neurons.

Abstract: Herpes simplex virus is most probably maintained in the ganglion neurons of the peripheral nervous system of humans in a latent form that can reactivate to produce recurrent disease. As an approximation of this cell-virus interaction, we have constructed a herpes simplex virus latency in vitro model system using human fetus sensory neurons as the host cell. Human fetus neurons were characterized as neuronal in origin by the detection of the neuropeptide substance P and the neuron-specific plasma membrane A2B5 antigen. Virus latency was established by blocking complete expression of the virus genome by treatment of infected human neurons with a combination of human leukocyte interferon and (E)-5-(2-bromovinyl)-2'-deoxyuridine for 7 days. After removal of inhibitors, virus latency was maintained for at least 9 days. This in vitro model will provide a system to analyze, in a primary human neuron, the state of the herpes simplex virus genome during establishment and maintenance of experimental latency.

Naming latencies as evidence for two modes of lexical retrieval

Abstract: Data are reported for response latencies to naming pictures of objects which show a systematic relationship between naming latency and two measures of item difficulty. Of primary interest was a reanalysis of full latency distributions on a picture-by-picture basis to explore the possibility that overall mean latencies could in actuality be composed of multiple independent latency populations. Results are discussed in terms of “automatic” versus “voluntary search” modes of word retrieval.

Bifurcated method and apparatus for floating point addition with decreased latency time

Abstract: Apparatus for decreasing the latency time associated with floating point addition and subtraction in a computer, using a novel bifurcated, pre-normalization/post-normalization approach that distinguishes between differences of floating point exponents.

Median Nerve F-Wave Conduction in Healthy Subjects

Abstract: This study of the normal median nerve was designed 1) to compare techniques of using the shortest and average F-wave latencies, F-wave values between extremities, and F-wave values with the conventional motor response values and 2) to determine the relationships between F-wave latency and arm length. We examined 40 median nerves in 20 subjects with no known pathology. The motor response latency was measured from wrist and elbow stimulation sites by conventional techniques. We then applied multiple stimuli at the same sites to record a series of 10 F-wave latencies and determined shortest and average F-wave latencies. Values of F-wave and M-response conduction are reported. No significant difference was found in F-wave latency or velocity between extremities within subjects, using either the shortest or average latency technique. We propose a formula for calculating the estimated F-wave distal latency based on the conventional motor response distal latency. The F-wave conduction velocities of the forearm were faster and more variable than the motor nerve conduction velocities. A high correlation was found between F-wave distal latency and arm length. Using the method described, the F wave can be a useful measure in evaluating the conduction of proximal segments of peripheral motor nerves.

Effects of click duration on the latency of the early evoked response

Abstract: The effect of click duration on the latency of waves I, III, and V was investigated by testing 20 normal-hearing subjects at 60 dB HL using electric pulses of 25, 50, 100, 200, and 400 µs. Alternat...

P300 Latency in Chronic Alcoholics and Depressed Patients

Abstract: The report by Goodin et al. (1978) that there is a significant correlation between impaired cognitive function in dementia and the latency of P300 has stimulated considerable interest in the use of P300 as a diagnostic tool. More recently, we demonstrated that P300 latency is also prolonged in chronic alcoholics (Pfefferbaum et al., 1979). This finding is consistent with that of Goodin et al. in that long-term alcoholism is known to lead to significant cognitive impairment (Eckardt et al., 1978). The P300 tasks used by Goodin et al. and by us in 1979 were simple, auditory discrimination, “oddball” paradigms. The extent of the delay in P300 latency observed in these studies was 40 to 50 ms. There are a t least two stages of stimulus processing that could account for delays of this magnitude. For example, Johnson and Kopell (1 980) demonstrated that stimulus-encoding time, as indexed by both reaction time (RT) and P300 latency, could be varied by this amount simply as a function of the preceding sequence of stimuli. If stimulus-encoding processes were impaired, we would expect P300 latency to be delayed by a constant amount regardless of task difficulty, provided the same stimuli were used. A more likely explanation is that stimulusencoding processes are normal in these patients and that the delays occur during stimulus evaluation. If this latter hypothesis is correct, then latency differences between patients and controls should increase as a function of task difficulty. In the present study, we test the latter hypothesis by using a set of three progressively more difficult tasks to elicit P300s. The tasks were chosen in order that we might localize the processing stage(s) responsible for the delayed P300 activity. Chronic alcoholics (i.e., 10 or more years of alcoholic drinking) served as subjects. They are compared to normal controls and drug-free depressed patients. The depressed patients were included because they often present with an apparent cognitive deficit which is

Two components of motor time: the tension lag and the tension-developing phase.

Abstract: Motor time (MT) of the rectus femoris muscle for knee extension under loading on the leg with different weights and latency of isometric tension from the onset of electromyographic activities of the muscle were examined in 7 normal men. MT was linearly related to weights-loaded, indicating that the rate of rapid development of tension was almost linear even in its early phase. MT without a load obtained by calculation using the regression equation and the estimated weight of the leg and foot coincided with latency of isometric tension. It is assumed that MT is composed of two consecutive phases, a tension-lag phase and a rapid tension-developing phase.

Short communication: The minimal average latency of multiconfigurable pipelines

Abstract: It is shown that the average latencies of all sequences of optimal cycles through a fixed vertex in the state graph of a multiconfigurable pipeline have a common limit, provided that their initiation numbers are unbounded and approximate the same ratio of the underlying operations. This leads to a definition of the minimal average latency of a multiconfigurable pipeline.

Contiguous approach conditioning: a model for sidman avoidance learning

Abstract: The study sought to extend M. R. Denny's contiguous approach conditioning model of instrumental reinforcement effects to account for Sidman avoidance conditioning. Experimental subjects (rats) received a 15-sec. duration light which was paired, independently of the subject's behavior, with the nonoccurrence of regularly scheduled 1-ma. shocks. Controls received light and shock unpaired. All subjects were then tested in a simple T-maze for approach to the light. Groups did not differ significantly in the direction of their initial response (approach or nonapproach to the light) but did differ in latency of approach to the light. Further, a significantly higher proportion of experimental subjects than control subjects approached the light within the 15 sec. that had been the “safety” period during pairing. While these findings are largely consistent with Denny's theory, they might also be taken to support expectancy or informational interpretations of Sidman avoidance.

Components of response latency in simple mental tasks

Abstract: Some models are presented that account for the effects of speed and precision 1n mental test scores as measured by time-limit intelligence tests. Focusing on the number of items correct and the number of items attempted, usually taken as estimators of these effects, it is shown that the Rasch model, and as a special case the binomial error model, can be used to estimate precision. As to speed, a model called the Poisson-Erlang model Is presented. It is shown that speed can be analysed into two components: processing time and distraction time. Parameters of the Poisson-Erlang model are used to estimate these components. Combining the different models an outline is given of a new method for analyzing time-limit tests. In addition, it is shown that the Poisson-Erlang model can be used to account for response latencies commonly observed in mental concentration tests. 2.

Maturational Changes in the Waveform of Auditory Middle Latency Responses

Abstract: The investigation using digital filtering on the auditory middle latency response (MLR) to click was performed and the results were compared in infants and adults.The subjects were 10 children aged 8 to 10, and 7 children aged 11 to 14. All of them were proved to have normal hearing. The waveforms of the infants changed gradually into the waveforms of the adults during the age of 8 to 14. Pa detectability on high pass filtering of 40Hz and Pb detectability of 20-40Hz increased gradually with aging, and reached to the adults score (100%). The peak Pa and Nb decreased in latency with aging. From these results, the existence of the maturational effects on the MLR is recognized, and the infant MLR changes into the adult MLR in around 13 to 14 years old.