Showing papers on "Latency (engineering) published in 1987"

Medium and long latency EMG responses in leg muscles: Parkinson's disease.

Abstract: Short, medium, and long latency EMG responses to muscle stretch from triceps surae and anterior tibialis muscles were recorded in normals and in 33 patients with Parkinson's disease. The latencies of all EMG responses except short latency were normal in patients with Parkinson's disease. The integrals of the medium latency responses in the stretched triceps surae muscle were significantly increased in patients. This result indicates a modulatory influence of the basal ganglia on medium latency EMG responses.

Herpes Simplex Virus Genes Involved in Latency in vitro

Abstract: Summary The properties of temperature-sensitive (ts), insertion or deletion mutants of herpes simplex virus (HSV) were investigated in an in vitro model system for latency. The studies defined virus gene products required for establishment of latency and for reactivation of latent virus. All mutants tested established latency in human foetal lung fibroblasts and could be reactivated by intertypic superinfection with HSV or with human cytomegalovirus. Two mutants of HSV type 1 used in these studies, tsK and in1411, failed to synthesize active immediate early (IE) polypeptide Vmw175 and were blocked at a very early stage of the virus replication cycle, showing that, at most, only limited gene expression is necessary for the establishment of latency. Mutant dl1403, which lacks the gene encoding IE polypeptide Vmw110, established latency as efficiently as wild-type HSV. Latent HSV type 2 was reactivated by superinfection with tsK or in1411 but not with dl1403, suggesting that polypeptide Vmw110, which is known to regulate gene expression by trans-activation, is required for reactivation in the in vitro system.

Measurement-Based Analysis of Error Latency

Abstract: This paper demonstrates a practical methodology for the study of error latency under a real workload. The method is illustrated with sampled data on the physical memory activity, gathered by hardware instrumentation on a VAX 11/780 during the normal workload cycle of the installation. These data are used to simulate fault occurrence and to reconstruct the error discovery process in the system. The technique provides a means to study the system under different workloads and for multiple days. An approach to determine the percentage of undiscovered errors is also developed and a verification of the entire methodology is performed. This study finds that the mean error latency, in the memory containing the operating system, varies by a factor of 10 to 1 (in hours) between the low and high workloads. It is found that of all errors occurring within a day, 70 percent are detected in the same day, 82 percent within the following day, and 91 percent within the third day. The increase in failure rate due to latency is not so much a function of remaining errors but is dependent on whether or not there is a latent error.

Long latency EMG responses in hand and leg muscles: cerebellar disorders.

Abstract: Electromyographic responses to stretches of hand muscles (first dorsal interosseus) and leg muscles (triceps surae, tibialis anterior) were investigated in patients with cerebellar disorders of different locations. Stimuli consisted of short dorsiflexions of the index finger during background force and in tilting (toe up) of a movable platform on which the subject stood. The most important findings were increased long latency responses in upper and lower extremities. For hand muscles it was the late part of the long latency complex, which was increased. For leg muscles it was the long latency response in the anterior tibialis muscle, the antagonist of the stretched triceps surae. The medium latency response in the triceps surae was unaffected. Latencies of the early segmental reflexes and the long latency responses were normal except for cases with peripheral neuropathy (moderate increase in latency of all EMG responses) and diseases affecting both the peripheral nerves and the dorsal columns (for example Friedreich's ataxia). The latter leads to a pronounced delay of the short latency response and a massive delay of the long latency complex in the first dorsal interosseus and of the long latency response in the anterior tibialis muscle.

Pattern-reversal visual evoked potentials: latency changes with gender and age.

Abstract: Pattern-reversal visual evoked potentials were studied in 123 volunteers with ages ranging from 20 to 77 years. The major positive component (P100) showed a shorter mean latency but a higher mean amplitude for females than males. The age-dependent increase in mean P100 latency was observed in the female group but not in the male group. The present data suggest that gender is more important than age in affecting the P100 latency.

Variation of sympathetic reflex latency in man.

Abstract: Microelectrode recordings of muscle nerve sympathetic activity (MSA) in man have shown a reflex relationship between heart beat and corresponding sympathetic burst, the latency of which is stable at rest and independent of heart rate. In peroneal nerve recordings in 35 healthy subjects this latency was reduced during the Valsalva manoeuvre by 120 ms (mean; range 40–245 ms; P < 0.001) from a mean value at rest of 1300 ms. Slow deep breathing and simulated diving shortened the latency by 60 (P < 0.001) and 80 ms (P < 0.05), respectively. When intrinsic heart rate was induced by i.v. administration of atropine and propranolol, the latency was increased by 70 ms (P < 0.001). A number of other manoeuvres affecting the outflow of MSA did not change the latency. It is suggested that the findings indicate the existence of more than one central pathway involved in the baroreflex regulation of MSA. Alternatively, altered central processing time may follow influence from other receptors in different manoeuvres.

Surveillance, latency and the two levels of MCA‐induced tumor immunogenicity

Abstract: Among 154 different, MCA-induced mouse sarcomas, the immunogenicities of those tumors that had had the shortest original latencies in their autochthonous hosts were of an intermediate level with relatively little scatter. This fact is not predicted by the theory of immunological surveillance, but does fit the predictions of the immunological facilitation theory of oncogenesis. The frequency distribution of the tumor immunogenicities showed 2 peaks; the cluster of higher immunogenicity had a shorter latency than did the cluster of lower immunogenicity. The data for tumors initiated within in vivo diffusion chambers also showed 2 immunogenicity clusters, suggesting that the discrete clusters were not caused by host immunity. However, immunity apparently reduced the mean latency of the more immunogenic cluster and/or lengthened the mean latency of the less immunogenic, a result also inconsistent with the theory of immunological surveillance.

Using Response Latency to Assess Spokesperson Effectiveness

Abstract: A response latency methodology was developed and used to assess spokesperson effectiveness. Results indicate that when a product identification decision was primed by a correct spokesperson name, subjects were able to identify product names as such significantly faster than when the decision was unprimed or misprimed. Based on the results of the latency experiment, characteristics of successful spokespersons were identified using multiple regression. Theoretical and methodological implications of the response latency technique are discussed.

Estimating the distribution of fault latency in a digital processor

Abstract: Presented is a statistical approach to measuring fault latency in a digital processor. The method relies on the use of physical fault injection where the duration of the fault injection can be controlled. Although a specific fault's latency period is never directly measured, the method indirectly determines the distribution of fault latency.

Gaze-position dependence of saccadic latency and accuracy

Abstract: Publisher Summary This chapter discusses the latency of saccadic eye movements. Some papers note that the latency of saccadic eye movements slightly increases with the size of the target displacement, whereas others find no latency increase up to 20 degrees. There may be a gaze-position dependence of saccadic latency and accuracy, and understanding the central mechanisms responsible for the generation of saccadic commands as well as their possible levels of action is essential. The study described involved experimental subjects who were asked to follow a dot visual target either with maximum velocity or maximum accuracy. The target moved randomly in time, with jumps of amplitude in a range of +/–35 degrees in the horizontal plane. The experiment concludes that latency variations, which were previously thought to result from the amplitude of the target displacement, are instead caused by the final target eccentricity. The bidirectional map represents the percent probability of occurrence of a corrective saccade at the coordinates.

Evaluating a Spatial Task: Behavioral, Subjective, and Physiological Correlates

Abstract: A spatial task, taken from the Criterion Task Set (CTS) battery, was used to examine task load effects on a variety of physiological indices. This task had been shown with earlier validation data (reaction time and subjective ratings) to possess three different levels of task load (Shingledecker, 1984). Task event-related evoked potentials (EPs), heart rate and heart rate variability, and eyeblink measures were obtained while ten subjects performed the three levels of the spatial task. The amplitudes of the P2, N2, and P3 of the EPs differentiated between the low task level, and the medium and high. Medium and high did not differentiate. The latencies of the N1, N2, and P3 were shorter for the low task level than for the medium and high. Again, medium and high did not differentiate. The amplitude and latency of the EP components suggest that this task possesses only two levels of information processing complexity. Heart rate and heart rate variability did not differentiate between task levels, only betwee...

Latency of the acoustic evoked stapedius reflex and its clinical significance

Abstract: We measured the mean latency of the stapedius reflex by normal listeners. We observed a prolongation of the latency by patients with operative and histological confirmed neurinoma of the VIII. nerve. Even if the measured stapedius reflex latency considerably varies, this method represents, any way, an important support to BERA to discover tumours of the cerebello-pontine angle.

The effect of eyespan training on P-300 latency

Abstract: A visual enhancement training program utilizing the Eyespan was evaluated for its effect on the P-300 latency. The P-300 latency is a cortical response occuring appoximately 300 ms. after a stimulus is presented. The latency of 16 subjects was measured under identical conditions before and after a training program. Eight subjects participated in three weeks of training involving 16 five minute sessions with the Eyespan. The other eight subjects served as control for the study. After the training program, results showed an insignificant change in latency of the experimental group, while the control group showed an increase in latency.

Evaluation of visual evoked potentials in chronic Parkinson disease patients

Abstract: The P-100 latency of the evoked visual potentials in 20 cases of idiopathic Parkinson's disease were examined. As indicated in earlier studies, P-100 latency was significantly higher in Parkinson patients than in healthy controls. The hypotheses about the pathogenesis of such anomalies are then discussed.