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Baker, Stuart N., et George L. Gerstein. « Determination of Response Latency and Its Application to Normalization of Cross-Correlation Measures ». Neural Computation 13, no 6 (1 juin 2001) : 1351–77. http://dx.doi.org/10.1162/08997660152002889.
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It is often of interest experimentally to assess how synchronization between two neurons changes following a stimulus or other behaviorally relevant marker. The joint peristimulus time histogram (JPSTH) achieves this, but assumes that changes in the cells' firing rate following the stimulus are stereotyped from one sweep to the next. Erroneous results can be generated if this is not the case. We here present a method to assess whether there are variations in response latency or amplitude from sweep to sweep. We then describe how the effects of response latency variation can be mitigated by realigning sweeps to their individual latencies. Three methods of detecting response latency are presented and their performance compared on simulated data. Finally, the effect on the JPSTH of sweep realignment using detected latencies is illustrated.
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Schmid, Andreas, David Halbhuber, Thomas Fischer, Raphael Wimmer et Niels Henze. « Small Latency Variations Do Not Affect Player Performance in First-Person Shooters ». Proceedings of the ACM on Human-Computer Interaction 7, CHI PLAY (29 septembre 2023) : 197–216. http://dx.doi.org/10.1145/3611027.
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In interactive systems high latency affects user performance and experience. This is especially problematic in video games. A large number of studies on this topic investigated the effects of constant, high latency. However, in practice, latency is never constant but varies by up to 100 ms due to variations in processing time and delays added by polling between system components. In a large majority of studies, these variations in latency are neither controlled for nor reported. Thus, it is unclear to which degree small, continuous variations in latency affect user performance. If these unreported variations had a significant impact, this might cast into doubt the findings of some studies. To investigate how latency variation affects player performance and experience in games, we conducted an experiment with 28 participants playing a first-person shooter. Participants played with two levels of base latency (50 ms vs. 150 ms) and variation (0 ms vs. 50 ms). As expected, high base latency significantly reduces player performance and experience. However, we found strong evidence that small variations in latency in the order of 50 ms, do not affect player performance significantly. Thus, our findings mitigate concerns that previous latency studies might have systematically ignored a confounding effect.
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Wu, Weixin, Yujie Dong et Adam Hoover. « Measuring Digital System Latency from Sensing to Actuation at Continuous 1-ms Resolution ». Presence : Teleoperators and Virtual Environments 22, no 1 (février 2013) : 20–35. http://dx.doi.org/10.1162/pres_a_00131.
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This paper describes a new method for measuring the end-to-end latency between sensing and actuation in a digital computing system. Compared to previous works, which generally measured the latency at 10–33-ms intervals or at discrete events separated by hundreds of ms, our new method measures the latency continuously at 1-ms resolution. This allows for the observation of variations in latency over sub 1-s periods, instead of relying upon averages of measurements. We have applied our method to two systems, the first using a camera for sensing and an LCD monitor for actuation, and the second using an orientation sensor for sensing and a motor for actuation. Our results show two interesting findings. First, a cyclical variation in latency can be seen based upon the relative rates of the sensor and actuator clocks and buffer times; for the components we tested, the variation was in the range of 15–50 Hz with a magnitude of 10–20 ms. Second, orientation sensor error can look like a variation in latency; for the sensor we tested, the variation was in the range of 0.5–1.0 Hz with a magnitude of 20–100 ms. Both of these findings have implications for robotics and virtual reality systems. In particular, it is possible that the variation in apparent latency caused by orientation sensor error may have some relation to simulator sickness.
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Kashio, Akinori, Viral D. Tejani, Rachel A. Scheperle, Carolyn J. Brown et Paul J. Abbas. « Exploring the Source of Neural Responses of Different Latencies Obtained from Different Recording Electrodes in Cochlear Implant Users ». Audiology and Neurotology 21, no 3 (2016) : 141–49. http://dx.doi.org/10.1159/000444739.
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In this study we measured the electrically evoked compound action potential (ECAP) from different recording electrodes in the cochlea. Under the assumption that different response latencies may be the result of differences in the neural population contributing to the response, we assessed the relationship between neural response latency and spread of excitation. First, we evaluated changes in N1 latency when the recording electrode site was varied. Second, we recorded channel interaction functions using a forward masking technique but with recording electrodes at different intracochlear locations. For most individuals, N1 latency was similar across recording electrodes. However, reduced N1 latencies were observed in 21% of cochlear implant users when ECAPs were recorded using a remote recording electrode. We hypothesized that if recordings from different electrodes represented contributions from different populations of neurons, then one might expect that channel interaction functions would be different. However, we did not observe consistent differences in channel interaction functions (neither peak location nor breadth of the functions), and further, any variation in channel interaction functions was not correlated with ECAP latency. These results suggest that ECAPs from different recording electrodes with different latencies originate from similar neural populations.
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Abdelkader, Hamed Ibrahem, Mona Abdelkader, Mohammed Kabeel et Malak Alya. « Visual Evoked potential signal processing and analysis for normal and galucomic eyes ». JOURNAL OF ADVANCES IN PHYSICS 8, no 2 (15 avril 2015) : 2106–21. http://dx.doi.org/10.24297/jap.v8i2.1516.
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Visual evoked potentials (VEPS) are obtained from optic tract by recording the evoked potentials generated by retinal stimulation. The flash VEP (FVEP) is used less frequently than pattern reversal VEP (PRVEP) because; it shows great variation in both latency and amplitude. The present study was undertaken to evaluate the effect of change of wavelength of flash and change of check size on the parameters of visual evoked potential (amplitude and latency) in normal individuals and glaucoma patients. The group of healthy subjects in the age of 20-45 years while the group of glaucoma subjects where  in the age of 25-50 years.  The two groups were exposed to flash VEP with white light and blue color and they also were exposed to checks subtending a visual angles of 15, 30,60 and 120 minutes of arc. The measured data were statistically analyzed and summarized by histograms. The interindividual and intraindividual in latencies and amplitudes for FVEP were assessed using  the coefficient of variation (COV). In conclusion, monochromatic flash VEP was preferred than white as there were minimal inter and intra individual variation of latencies and amplitudes. The most preferred check size in PRVEP was 120' for  the two groups. Â
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Ventura, Valérie. « Testing for and Estimating Latency Effects for Poisson and Non-Poisson Spike Trains ». Neural Computation 16, no 11 (1 novembre 2004) : 2323–49. http://dx.doi.org/10.1162/0899766041941952.
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Determining the variations in response latency of one or several neurons to a stimulus is of interest in different contexts. Two common problems concern correlating latency with a particular behavior, for example, the reaction time to a stimulus, and adjusting tools for detecting synchronization between two neurons. We use two such problems to illustrate the latency testing and estimation methods developed in this article. Our test for latencies is a formal statistical test that produces a p-value. It is applicable for Poisson and non-Poisson spike trains via use of the bootstrap. Our estimation method is model free, it is fast and easy to implement, and its performance compares favorably to other methods currently available.
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McGarry, Tim, Romeo Chua et Ian M. Franks. « Stopping and Restarting an Unfolding Action at Various Times ». Quarterly Journal of Experimental Psychology Section A 56, no 4 (mai 2003) : 1–20. http://dx.doi.org/10.1080/02724980244000549.
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The ability to inhibit an unfolding action is usually investigated using a stop signal (or go—stop) task. The data from the stop-signal task are often described using a horse-race model whose key assumption is that each process (i.e., go, stop) exhibits stochastic independence. Using three variations of a coincident-timing task (i.e., go, go—stop, and go—stop—go) we extend previous considerations of stochastic independence by analysing the go latencies for prior effects of stopping. On random trials in the go—stop—go task the signal sweep was paused for various times at various distances before the target. Significant increases in latency errors were reported on those trials on which the signal was paused (p <.005). Further analyses of the pause trials revealed significant effects for both the stopping interval (p <.001) and the pause interval (p <.05). Tukey post hoc analyses demonstrated increased latency errors as a linear function of the stopping interval, as expected, and decreased latency errors as a nonlinear function of the pause interval. These latter results indicate that the latencies of the go process, as reflected in the latency errors, may not exhibit stochastic independence under certain conditions. Various control mechanisms were considered in an attempt to explain these data.
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Lee, Joonyeol, Timothy R. Darlington et Stephen G. Lisberger. « The Neural Basis for Response Latency in a Sensory-Motor Behavior ». Cerebral Cortex 30, no 5 (11 décembre 2019) : 3055–73. http://dx.doi.org/10.1093/cercor/bhz294.
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Abstract We seek a neural circuit explanation for sensory-motor reaction times. In the smooth eye movement region of the frontal eye fields (FEFSEM), the latencies of pairs of neurons show trial-by-trial correlations that cause trial-by-trial correlations in neural and behavioral latency. These correlations can account for two-third of the observed variation in behavioral latency. The amplitude of preparatory activity also could contribute, but the responses of many FEFSEM neurons fail to support predictions of the traditional “ramp-to-threshold” model. As a correlate of neural processing that determines reaction time, the local field potential in FEFSEM includes a brief wave in the 5–15-Hz frequency range that precedes pursuit initiation and whose phase is correlated with the latency of pursuit in individual trials. We suggest that the latency of the incoming visual motion signals combines with the state of preparatory activity to determine the latency of the transient response that controls eye movement. Impact statement The motor cortex for smooth pursuit eye movements contributes to sensory-motor reaction time through the amplitude of preparatory activity and the latency of transient, visually driven responses.
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Ghozlan, A., et D. Widlöcher. « Decision Time and Movement Time in Depression : Differential Effects of Practice before and after Clinical Improvement ». Perceptual and Motor Skills 68, no 1 (février 1989) : 187–92. http://dx.doi.org/10.2466/pms.1989.68.1.187.
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Choice reaction time involves, at least two components of response latency, decision time and movement time. Studies of choice reaction time usually provide values of these two components averaged over a given number of trials. The aim of the present study of depressed subjects was to investigate changes across practice on Decision Time (DT) and Movement Time (MT) before and after clinical improvement. 19 depressed subjects were given two sessions of 50 trials each, one before treatment (Di) and one after recovery (Df). Decision time and movement time exhibited quite different patterns. Decision time significantly decreased with clinical improvement. No significant variation across trials was found, in either session. Movement time values varied across trials but the variations observed on Di and Df were significantly different, whereas before treatment latencies recorded at the end of the session were greater than those scored at the start, the contrary was observed after clinical recovery. No significant difference was found between values of movement time scored at the start of the two sessions.
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Gupta, Saket, et Sachin S. Sapatnekar. « Variation-Aware Variable Latency Design ». IEEE Transactions on Very Large Scale Integration (VLSI) Systems 22, no 5 (mai 2014) : 1106–17. http://dx.doi.org/10.1109/tvlsi.2013.2265662.
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Shu, Liu, Feng, Xu, Qian et Yang. « Analysis of Factors Affecting Asynchronous RTK Positioning with GNSS Signals ». Remote Sensing 11, no 10 (27 mai 2019) : 1256. http://dx.doi.org/10.3390/rs11101256.
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For short baseline real-time kinematic (RTK) positioning, the atmosphere and broadcast ephemeris errors can be usually eliminated in double-differenced (DD) processing for synchronous observations. However, in the case of possible communication latency time, these errors may not be eliminated in DD treatments due to their variations during latency time. In addition, the time variation of these errors may present different characteristics among GPS, GLONASS, BDS, and GALILEO due to different satellite orbit and clock types. In this contribution, the formulas for studying the broadcast orbit and clock offset errors and atmosphere error in asynchronous RTK (ARTK) model is proposed, and comprehensive experimental analysis is performed to numerically show time variations of these errors and their impacts on RTK results from short-baselines among four systems. Compared with synchronous RTK, the degradation of position precision for ARTK can reach a few centimeters, but the accuracy degradation to a different degree by different systems. BDS and Galileo usually outperform GPS and GLONASS in ARTK due to the smaller variation of broadcast ephemeris error. The variation of broadcast orbit error is generally negligible compared with the variation of broadcast clock offset error for GPS, BDS, and Galileo. Specifically, for a month of data, the root mean square (RMS) values for the variation of broadcast ephemeris error over 15 seconds are 11.2, 16.9, 7.3, and 3.0 mm for GPS, GLONASS, BDS, and Galileo, respectively. The variation of ionosphere error for some satellites over 15 seconds can reach a few centimeters during active sessions under a normal ionosphere day. In addition, compared with other systems, BDS ARTK shows an advantage under high ionosphere activity, and such advantage may be attributed to five GEO satellites in the BDS constellation.
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Mulder, Leslie J., et Dario Tedeschi. « An Examination of the Latencies Found in a Wi-SUN FAN Network ». International Journal of Media and Networks 2, no 9 (2 octobre 2024) : 01–06. http://dx.doi.org/10.33140/ijmn.02.09.02.
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This paper reports on the results of multicast latency and round trip time measurements for a particular deployment of nodes forming a Wi-SUN FAN 1.0 network [1]. The authors have explored in detail the behaviour of the WiSUN FAN network used by Hee-Jun Lee and Sang-Hwa Chung, the authors of a prior paper, in order to provide more detail regarding the latencies and delays cited in that paper [2]. We provide details regarding: • the timing of the component requests and responses that comprise the Lee and Chung round-trip and latency measurements, and • additional timing and packet delivery ratio results for variations of the MPL retransmission parameters for the Wi-SUN FAN protocol used on the Lee and Chung test network [3].
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Sarker, Shinjini, Sakhawat Hossain, Nawsabah Noor, Anjuman Ara Begum, Md Khairuzzaman et Pijous Biswas. « Electrophysiological variations of Guillain-Barre syndrome in Bangladesh- Hospital based study ». Journal of Medicine 25, no 1 (4 janvier 2024) : 11–16. http://dx.doi.org/10.3329/jom.v25i1.70520.
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Introduction: Guillain-Barre syndrome (GBS) is an immune mediated disorder of peripheral nerves which usually presents by rapidly evolving ascending weakness & mild sensory loss and hypo- or areflexia. Electrodiagnostic study (EDS) is the basis for classification of different subtypes of the disease. EDS also has a crucial role in diagnosis, ruling out of some differential diagnosis like myopathic and motor neuron disorders and confirming the neuropathic nature of GBS. The benefit of immunotherapy is greatest when introduced early. In addition, electrophysiological characteristic can predict the prognosis of patients with GBS. This study was conducted to determine the predominant subtype and electrophysiological pattern of GBS in the context of Bangladesh. Objectives: Objective of this study was to compare the electrophysiological variations among different electrophysiological subtypes of GBS. Methods: It is an observational cross sectional study conducted in Department of Medicine and Neurology, Sir Salimullah Medical College & Mitford Hospital and National Institute of Neuroscience (NINS), Dhaka, over a period of one year & four months. Total 30 patients were selected by purposive sampling technique. Demographic data were collected from the patients and recorded in structured case report form. Clinical examination and relevant investigations were done meticulously. Collected questionnaire were checked to identify any error in data. Data was analyzed with SPSS version 21 software. Result: In this study, maximum numbers of patients 53% were between 21-30 years of age group with mean value 27.47±8.1 years. Male to female ratio was 1.7:1. Frequency of Guillain-Barre syndrome is predominance at middle age group. Commonest presentation was limb weakness (parapledgia or quadripledgia) in 60% patients, paresthesias & numbness (40%), pain (100%) and deviation of mouth (63%) of GBS patients. Cerebrospinal fluid shows a mild pleocytosis (5 to 50 cells/µl) in majority of cases was found in 76% of patients. Whereas elevated CSF Protein (>45 mg/dl) was seen in all GBS patient. Increased distal motor latency (DML) was found in 93% patients, whereas 7% patients had normal DML. In the case of the lower limbs, increased distal motor latency was predominant. Decreased amplitude of sensory nerve action potential (SNAP) was seen in 83% patients while 16% patients had normal. Slowing of motor conduction velocities, decreased amplitude as well as increase in distal motor latencies were observed, being more pronounced in the lower limbs. F-wave was completely absent in 20.0% patients while 20% patients showed decreased conduction velocity with prolonged latency. Sensory nerve action potential revealed that decreased sensory conduction velocity (SCV) was seen in 26%, absent SCV in 10% and normal SCV in 63% patients. Present study demonstrated that Acute inflammatory demyelinating polyneuropathy (AIDP) was the commonest type of Guillain-Barré syndrome, present in 56% of patient. Around 30% of the patients belonged to acute motor axonal polyneuropathy (AMAN) and 13% were acute motor sensory axonal polyneuropathy (AMSAN). Conclusion: In this study AIDP was the most frequent subtype. The characteristic findings supportive of AIDP include prolonged distal motor latencies, reduced conduction velocities, conduction blocks at non-entrapment sites, temporal dispersion and prolonged F wave latencies. J MEDICINE 2024; 25: 11-16
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Perez, Ana, Karin Ziliotto et Liliane Pereira. « Test-Retest of Long Latency Auditory Evoked Potentials (P300) with Pure Tone and Speech Stimuli ». International Archives of Otorhinolaryngology 21, no 02 (26 avril 2016) : 134–39. http://dx.doi.org/10.1055/s-0036-1583527.
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Introduction Long latency auditory evoked potentials, especially P300, have been used for clinical evaluation of mental processing. Many factors can interfere with Auditory Evoked Potential - P300 results, suggesting large intra and inter-subject variations. Objective The objective of the study was to identify the reliability of P3 components (latency and amplitude) over 4–6 weeks and the most stable auditory stimulus with the best test-retest agreement. Methods Ten normal-hearing women participated in the study. Only subjects without auditory processing problems were included. To determine the P3 components, we elicited long latency auditory evoked potential (P300) by pure tone and speech stimuli, and retested after 4–6 weeks using the same parameters. We identified P300 latency and amplitude by waveform subtraction. Results We found lower coefficient of variation values in latency than in amplitude, with less variability analysis when speech stimulus was used. There was no significant correlation in latency measures between pure tone and speech stimuli, and sessions. There was a significant intrasubject correlation between measures of latency and amplitude. Conclusion These findings show that amplitude responses are more robust for the speech stimulus when compared with its pure tone counterpart. The P300 indicated stability for latency and amplitude measures when the test-retest was applied. Reliability was higher for amplitude than for latency, with better agreement when the pure tone stimulus was used. However, further research with speech stimulus is needed to clarify how these stimuli are processed by the nervous system.
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Morkavuk, G., et A. Leventoglu. « Small Fiber Neuropathy Associated with Hyperlipidemia : Utility of Cutaneous Silent Periods and Autonomic Tests ». ISRN Neurology 2014 (19 mars 2014) : 1–6. http://dx.doi.org/10.1155/2014/579242.
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Background. Established electrophysiological methods have limited clinical utility in the diagnosis of small fiber neuropathy. The cutaneous silent period (CSP) may be useful as a method for the evaluation of smaller and unmyelinated fiber dysfunctions. Hyperlipidemia is a very rare cause of small fiber neuropathy. In this study, hyperlipidemia and small fiber neuropathy in symptomatic patients with normal nerve conduction studies were evaluated with autonomic tests and cutaneous silent periods. Methods. Twenty-five patients with clinically suspected small fiber neuropathy and 23 healthy volunteers were included. CSP latency and duration, as well as CSP latency difference of the upper and lower extremities, were examined. Two tests were used to assess the autonomic nervous system, namely, the R-R interval variation test in basal and profound breath conditions and the sympathetic skin response. Results. Twenty-five patients with clinically suspected small fiber neuropathy and normal nerve conduction studies were compared with 23 controls. In the upper extremities, patients had prolonged CSP latencies (P=0.034) and shortened CSP durations (P=0.039), whereas in the lower extremities, patients had shortened CSP durations (P=0.001). The expiration-to-inspiration ratios were also reduced in patients groups. There was no significant difference between sympathetic skin response latencies and amplitude of the case and control groups. Conclusion. Our findings indicate that CSP may become a useful technique for the assessment of small fiber neuropathy in hyperlipidemic patients.
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Masapollo, Matthew, et Susan Nittrouer. « Immediate auditory feedback regulates inter-articulator speech coordination in service to phonetic structure ». Journal of the Acoustical Society of America 156, no 3 (1 septembre 2024) : 1850–61. http://dx.doi.org/10.1121/10.0028725.
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Research has shown that talkers reliably coordinate the timing of articulator movements across variation in production rate and syllable stress, and that this precision of inter-articulator timing instantiates phonetic structure in the resulting acoustic signal. We here tested the hypothesis that immediate auditory feedback helps regulate that consistent articulatory timing control. Talkers with normal hearing recorded 480 /tV#Cat/ utterances using electromagnetic articulography, with alternative V (/ɑ/-/ɛ/) and C (/t/-/d/), across variation in production rate (fast-normal) and stress (first syllable stressed-unstressed). Utterances were split between two listening conditions: unmasked and masked. To quantify the effect of immediate auditory feedback on the coordination between the jaw and tongue-tip, the timing of tongue-tip raising onset for C, relative to the jaw opening-closing cycle for V, was obtained in each listening condition. Across both listening conditions, any manipulation that shortened the jaw opening-closing cycle reduced the latency of tongue-tip movement onset, relative to the onset of jaw opening. Moreover, tongue-tip latencies were strongly affiliated with utterance type. During auditory masking, however, tongue-tip latencies were less strongly affiliated with utterance type, demonstrating that talkers use afferent auditory signals in real-time to regulate the precision of inter-articulator timing in service to phonetic structure.
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Chang, Kevin K., Abhijith Kashyap, Hasan Hassan, Saugata Ghose, Kevin Hsieh, Donghyuk Lee, Tianshi Li, Gennady Pekhimenko, Samira Khan et Onur Mutlu. « Understanding Latency Variation in Modern DRAM Chips ». ACM SIGMETRICS Performance Evaluation Review 44, no 1 (30 juin 2016) : 323–36. http://dx.doi.org/10.1145/2964791.2901453.
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White, A., S. Tatam, D. Linares et A. Holcombe. « Visuomotor compensation for variation in perceptual latency ». Journal of Vision 9, no 8 (3 septembre 2010) : 841. http://dx.doi.org/10.1167/9.8.841.
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Fagius, Jan, Göran Sundlöf et B. Gunnar Wallin. « Variation of sympathetic reflex latency in man ». Journal of the Autonomic Nervous System 21, no 2-3 (décembre 1987) : 157–65. http://dx.doi.org/10.1016/0165-1838(87)90018-x.
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Chichibu, Shiko, Atsushi Chiba, Takahide Sugiyama et Takashi Kurita. « Latency variation and habituation in cremasteric reflex ». Neuroscience Research Supplements 9 (janvier 1989) : 43. http://dx.doi.org/10.1016/0921-8696(89)90590-2.
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Larsen, T. E., S. B. Mogensen et I. Holme. « Seasonal variations of pigmented naevi. Intercorrelations of clinical and histological variables with special reference to seasonal variation. » Acta Dermato-Venereologica 70, no 2 (1 mars 1990) : 115–20. http://dx.doi.org/10.2340/0001555570115120.
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During 1984, junctional and compound naevi were registered significantly more often during the summer half-year (May-October) than the total number of naevi, which showed no seasonal variation. A series of 342 of these junctional and compound naevi have been the subject of a blind histological classification. Clinical information was obtained by a questionnaire mailed to the patients. The intercorrelations of 19 histological and 10 clinical variables were studied by chi 2-test. The seasonal variation of these variables was further studied by chi 2-test and by Hewitt's test. Patient's hair colour, eye colour and sex as well as mitoses and localization showed a significant correlation to season of the year. The trends of these findings, compared with the information about tumour duration, indicate a short-term latency effect of UV light on naevi which are excised during the summer half-year.
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Ramteke, Bhimraj B., et Sushil N. Meshram. « Latency and amplitude of P300 using speech and non-speech stimuli - a normative study ». International Journal of Otorhinolaryngology and Head and Neck Surgery 6, no 10 (23 septembre 2020) : 1867. http://dx.doi.org/10.18203/issn.2454-5929.ijohns20204191.
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<p class="abstract"><strong>Background:</strong> The P300 was among the first auditory response in a collection of events related or endogenous evoked responses. The P300 is related to cognition and use of knowledge about the environment.</p><p class="abstract"><strong>Methods:</strong> The subjects (n=60) selected with an equal distribution of genders. P300 evoked potentials elicited by non-speech and speech stimuli is recorded. </p><p class="abstract"><strong>Results:</strong> There is a significant difference in latency of P300 for speech verses non-speech stimuli as well as there is a significant difference in the latency of P300 among males and females for speech versus non speech stimuli. No significant difference in amplitude of P300 for speech versus non-speech stimuli and for right versus left ears.</p><p class="abstract"><strong>Conclusions:</strong> P300 latency is influenced by stimulus used and gender variation. The present study showed that the non-speech stimuli had lower latencies compared with speech stimuli. For the P300 amplitude values, the difference between groups were not significant.</p>
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Young, E. D., J. M. Robert et W. P. Shofner. « Regularity and latency of units in ventral cochlear nucleus : implications for unit classification and generation of response properties ». Journal of Neurophysiology 60, no 1 (1 juillet 1988) : 1–29. http://dx.doi.org/10.1152/jn.1988.60.1.1.
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1. The responses of neurons in the ventral cochlear nucleus (VCN) of decerebrate cats are described with regard to their regularity of discharge and latency. Regularity is measured by estimating the mean and standard deviation of interspike intervals as a function of time during responses to short tone bursts (25 ms). This method extends the usual interspike-interval analysis based on interval histograms by allowing the study of temporal changes in regularity during transient responses. The coefficient of variation (CV), equal to the ratio of standard deviation to mean interspike interval, is used as a measure of irregularity. Latency is measured as the mean and standard deviation of the latency of the first spike in response to short tone bursts, with 1.6-ms rise times. 2. The regularity and latency properties of the usual PST histogram response types are shown. Five major PST response type classes are used: chopper, primary-like, onset, onset-C, and unusual. The presence of a prepotential in a unit's action potentials is also noted; a prepotential implies that the unit is recorded from a bushy cell. 3. Units with chopper PST histograms give the most regular discharge. Three varieties of choppers are found. Chop-S units (regular choppers) have CVs less than 0.35 that are approximately constant during the response; chop-S units show no adaptation of instantaneous rate, as measured by the inverse of the mean interspike interval. Chop-T units have CVs greater than 0.35, show an increase in irregularity during the response and show substantial rate adaptation. Chop-U units have CVs greater than 0.35, show a decrease in irregularity during the response, and show a variety of rate adaptation behaviors, including negative adaptation (an increase in rate during a short-tone response). Irregular choppers (chop-T and chop-U units) rarely have CVs greater than 0.5. Choppers have the longest latencies of VCN units; all three groups have mean latencies at least 1 ms longer than the shortest auditory nerve (AN) fiber mean latencies. 4. Chopper units are recorded from stellate cells in VCN (35, 42). Our results for chopper units suggest a model for stellate cells in which a regularly firing action potential generator is driven by the summation of the AN inputs to the cell, where the summation is low-pass filtered by the membrane capacitance of the cell.(ABSTRACT TRUNCATED AT 400 WORDS)
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Mogil, Jeffrey S., Shad B. Smith, Meghan K. O'Reilly et Gilles Plourde. « Influence of Nociception and Stress-induced Antinociception on Genetic Variation in Isoflurane Anesthetic Potency among Mouse Strains ». Anesthesiology 103, no 4 (1 octobre 2005) : 751–58. http://dx.doi.org/10.1097/00000542-200510000-00013.
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Background Genetic background influences anesthetic potency to suppress motor response to noxious stimulation (minimum alveolar concentration [MAC]) as well as nociceptive sensitivity in unmedicated animals. However, the influence on MAC of baseline sensitivity to the noxious stimuli used to assess MAC has virtually never been studied. The authors assessed room air nociceptive sensitivity and isoflurane MAC in multiple mouse strains. Isoflurane requirement for loss of righting response (MACLORR) was also measured. Methods One outbred and 10 inbred mouse strains were tested for latency to respond (in room air) to a tail clip (either 500 g or 2,000 g). Naive mice of the same 11 strains were tested for isoflurane MAC and MACLORR. To assess the role of opioid-mediated stress-induced antinociception, mice were also tested for nociceptive sensitivity after injection of naloxone (10 mg/kg) or saline. Results Robust strain differences were observed for all measures. The authors found that tail-clip latency (using a 500-g or 2,000-g clip, respectively) correlated significantly with MAC (r = -0.76 and -0.58, respectively) but not MACLORR (r = -0.10 and -0.26). Naloxone produced strain-dependent reductions in open air tail-clip latencies, and these reductions were also strongly correlated with MAC (r = -0.67 and -0.71). Conclusions The authors suggest that genetic variability in isoflurane MAC (but not MACLORR) may reflect genetic variability in the underlying sensitivity to the noxious stimulus being used to measure MAC. This variable sensitivity to nociception in the awake state is at least partially mediated by endogenous antinociceptive mechanisms activated by the tail-clip stimulus itself.
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Stecker, G. Christopher, Brian J. Mickey, Ewan A. Macpherson et John C. Middlebrooks. « Spatial Sensitivity in Field PAF of Cat Auditory Cortex ». Journal of Neurophysiology 89, no 6 (juin 2003) : 2889–903. http://dx.doi.org/10.1152/jn.00980.2002.
Texte intégralRésumé :
We compared the spatial tuning properties of neurons in two fields [primary auditory cortex (A1) and posterior auditory field (PAF)] of cat auditory cortex. Broadband noise bursts of 80-ms duration were presented from loudspeakers throughout 360° in the horizontal plane (azimuth) or 260° in the vertical median plane (elevation). Sound levels varied from 20 to 40 dB above units' thresholds. We recorded neural spike activity simultaneously from 16 sites in field PAF and/or A1 of α-chloralose-anesthetized cats. We assessed spatial sensitivity by examining the dependence of spike count and response latency on stimulus location. In addition, we used an artificial neural network (ANN) to assess the information about stimulus location carried by spike patterns of single units and of ensembles of 2–32 units. The results indicate increased spatial sensitivity, more uniform distributions of preferred locations, and greater tolerance to changes in stimulus intensity among PAF units relative to A1 units. Compared to A1 units, PAF units responded at significantly longer latencies, and latencies varied more strongly with stimulus location. ANN analysis revealed significantly greater information transmission by spike patterns of PAF than A1 units, primarily reflecting the information transmitted by latency variation in PAF. Finally, information rates grew more rapidly with the number of units included in neural ensembles for PAF than A1. The latter finding suggests more accurate population coding of space in PAF, made possible by a more diverse population of neural response types.
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Bidelman, Gavin M., Monique Pousson, Calli Dugas et Amy Fehrenbach. « Test–Retest Reliability of Dual-Recorded Brainstem versus Cortical Auditory-Evoked Potentials to Speech ». Journal of the American Academy of Audiology 29, no 02 (février 2018) : 164–74. http://dx.doi.org/10.3766/jaaa.16167.
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AbstractAuditory-evoked potentials have proven useful in the objective evaluation of sound encoding at different stages of the auditory pathway (brainstem and cortex). Yet, their utility for use in clinical assessment and empirical research relies critically on the precision and test–retest repeatability of the measure.To determine how subcortical/cortical classes of auditory neural responses directly compare in terms of their internal consistency and test–retest reliability within and between listeners.A descriptive cohort study describing the dispersion of electrophysiological measures.Eight young, normal-hearing female listeners.We recorded auditory brainstem responses (ABRs), brainstem frequency-following responses (FFRs), and cortical (P1-N1-P2) auditory-evoked potentials elicited by speech sounds in the same set of listeners. We reassessed responses within each of four different test sessions over a period of 1 mo, allowing us to detect possible changes in latency/amplitude characteristics with finer detail than in previous studies.Our findings show that brainstem and cortical amplitude/latency measures are remarkably stable; with the exception of slight prolongation of the P1 wave, we found no significant variation in any response measure. Intraclass correlation analysis revealed that the speech-evoked FFR amplitude and latency measures achieved superior repeatability (intraclass correlation coefficient >0.85) among the more widely used obligatory brainstem (ABR) and cortical (P1-N1-P2) auditory-evoked potentials. Contrasting these intersubject effects, intrasubject variability (i.e., within-subject coefficient of variation) revealed that while latencies were more stable than amplitudes, brainstem and cortical responses did not differ in their variability at the single subject level.We conclude that (1) the variability of auditory neural responses increases with ascending level along the auditory neuroaxis (cortex > brainstem) between subjects but remains highly stable within subjects and (2) speech-FFRs might provide a more stable measure of auditory function than other conventional responses (e.g., click-ABR), given their lower inter- and intrasubject variability.
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Pelletier, J. Guillaume, et Denis Paré. « Uniform Range of Conduction Times From the Lateral Amygdala to Distributed Perirhinal Sites ». Journal of Neurophysiology 87, no 3 (1 mars 2002) : 1213–21. http://dx.doi.org/10.1152/jn.00623.2001.
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Much data indicate that the perirhinal (PRH) cortex plays a critical role in declarative memory and that the amygdala facilitates this process under emotionally arousing conditions. However, assuming that the amygdala does so by promoting Hebbian interactions in the PRH cortex is hard to reconcile with the fact that variable distances separate amygdala neurons from their PRH projection sites. Indeed, to achieve a synchronized activation of distributed PRH sites, amygdala axons should display a uniform range of conduction times, irrespective of distance to target. To determine if amygdala axons meet this condition, we measured the antidromic response latencies of lateral amygdala (LA) neurons to electrical stimuli delivered at various rostrocaudal levels of the PRH cortex in cats anesthetized with isoflurane. Although large variations in antidromic response latencies were observed, they were unrelated to the distance between the PRH stimulation sites and LA neurons. To determine whether this result was an artifact due to current spread, two control experiments were performed. First, we examined the antidromic response latency of intrinsic PRH neurons. Although we used the same methods as in the first experiment, the antidromic response latency of PRH neurons to electrical stimuli applied in the PRH cortex increased linearly with the distance between the stimulating and recording sites. Second, we measured the antidromic response latency of PRH neurons projecting to the LA. In this pathway, we also found a statistically significant correlation between conduction times and distance to target. Thus these results support the intriguing possibility that the conduction velocity and/or trajectory of LA axons are adjusted to compensate for variations in distance between the LA and distinct rostrocaudal PRH sites. We hypothesize that because of their uniform range of conduction times to the PRH cortex, LA neurons can generate short time windows of depolarization facilitating Hebbian associations between coincident, but spatially distributed, activity patterns in the PRH cortex. In this context, the temporal scatter of conduction times in the LA to PRH pathway is conceived as a mechanism used to lengthen the period of depolarization to compensate for conduction delays within intrinsic PRH pathways. In part, this mechanism might explain how the amygdala promotes memory storage in emotionally arousing conditions.
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Ray, Kaustabha, et Ansuman Banerjee. « Horizontal Auto-Scaling for Multi-Access Edge Computing Using Safe Reinforcement Learning ». ACM Transactions on Embedded Computing Systems 20, no 6 (30 novembre 2021) : 1–33. http://dx.doi.org/10.1145/3475991.
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Multi-Access Edge Computing (MEC) has emerged as a promising new paradigm allowing low latency access to services deployed on edge servers to avert network latencies often encountered in accessing cloud services. A key component of the MEC environment is an auto-scaling policy which is used to decide the overall management and scaling of container instances corresponding to individual services deployed on MEC servers to cater to traffic fluctuations. In this work, we propose a Safe Reinforcement Learning (RL)-based auto-scaling policy agent that can efficiently adapt to traffic variations to ensure adherence to service specific latency requirements. We model the MEC environment using a Markov Decision Process (MDP). We demonstrate how latency requirements can be formally expressed in Linear Temporal Logic (LTL). The LTL specification acts as a guide to the policy agent to automatically learn auto-scaling decisions that maximize the probability of satisfying the LTL formula. We introduce a quantitative reward mechanism based on the LTL formula to tailor service specific latency requirements. We prove that our reward mechanism ensures convergence of standard Safe-RL approaches. We present experimental results in practical scenarios on a test-bed setup with real-world benchmark applications to show the effectiveness of our approach in comparison to other state-of-the-art methods in literature. Furthermore, we perform extensive simulated experiments to demonstrate the effectiveness of our approach in large scale scenarios.
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Lee, Donghyuk, Samira Khan, Lavanya Subramanian, Saugata Ghose, Rachata Ausavarungnirun, Gennady Pekhimenko, Vivek Seshadri et Onur Mutlu. « Design-Induced Latency Variation in Modern DRAM Chips ». ACM SIGMETRICS Performance Evaluation Review 45, no 1 (18 septembre 2017) : 54. http://dx.doi.org/10.1145/3143314.3078533.
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Lee, Donghyuk, Samira Khan, Lavanya Subramanian, Saugata Ghose, Rachata Ausavarungnirun, Gennady Pekhimenko, Vivek Seshadri et Onur Mutlu. « Design-Induced Latency Variation in Modern DRAM Chips ». Proceedings of the ACM on Measurement and Analysis of Computing Systems 1, no 1 (13 juin 2017) : 1–36. http://dx.doi.org/10.1145/3084464.
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Jacobsen, Frederick M., Adriana Dreizzen et Thomas A. Wehr. « Diurnal mood variation and REM latency in depression ». Biological Psychiatry 22, no 8 (août 1987) : 1045–47. http://dx.doi.org/10.1016/0006-3223(87)90020-5.
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Jacobsen, Frederick M., Adriana Dreizzen et Thomas A. Wehr. « Diurnal mood variation and REM latency in depression ». Biological Psychiatry 22, no 6 (juin 1987) : 800–801. http://dx.doi.org/10.1016/0006-3223(87)90220-4.
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Arnarson, Hallgrímur, Arnar Pálsson, Margrét Gudnadóttir et Valgerdur Andrésdóttir. « Maedi-visna virus persistence : Antigenic variation and latency ». Comparative Immunology, Microbiology and Infectious Diseases 55 (décembre 2017) : 6–12. http://dx.doi.org/10.1016/j.cimid.2017.08.003.
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Burton, M. J., J. M. Miller et P. R. Kileny. « Middle-Latency Responses : II. Variation Among Stimulation Sites ». Archives of Otolaryngology - Head and Neck Surgery 115, no 4 (1 avril 1989) : 458–61. http://dx.doi.org/10.1001/archotol.1989.01860280056017.
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Opara, Ralf, et Florentin Wörgötter. « Using Visual Latencies to Improve Image Segmentation ». Neural Computation 8, no 7 (octobre 1996) : 1493–520. http://dx.doi.org/10.1162/neco.1996.8.7.1493.
Texte intégralRésumé :
An artificial neural network model is proposed that combines several aspects taken from physiological observations (oscillations, synchronizations) with a visual latency mechanism in order to achieve an improved analysis of visual scenes. The network consists of two parts. In the lower layers that contain no lateral connections the propagation velocity of the activity of the units depends on the contrast of the individual objects in the scene. In the upper layers lateral connections are used to achieve synchronization between corresponding image parts. This architecture assures that the activity that arises in response to a scene containing objects with different contrast is spread out over several layers in the network. Thereby adjacent objects with different contrast will be separated and synchronization occurs in the upper layers without mutual disturbance between different objects. A comparison with a one-layer network shows that synchronization in the latency dependent multilayer net is indeed achieved much faster as soon as more than five objects have to be recognized. In addition, it is shown that the network is highly robust against noise in the stimuli or variations in the propagation delays (latencies), respectively. For a consistent analysis of a visual scene the different features of an individual object have to be recognized as belonging together and separated from other objects. This study shows that temporal differences, naturally introduced by stimulus latencies in every biological sensory system, can strongly improve the performance and allow for an analysis of more complex scenes.
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Prévost, François, et Alexandre Lehmann. « Saliency of Vowel Features in Neural Responses of Cochlear Implant Users ». Clinical EEG and Neuroscience 49, no 6 (24 avril 2018) : 388–97. http://dx.doi.org/10.1177/1550059418770051.
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Cochlear implants restore hearing in deaf individuals, but speech perception remains challenging. Poor discrimination of spectral components is thought to account for limitations of speech recognition in cochlear implant users. We investigated how combined variations of spectral components along two orthogonal dimensions can maximize neural discrimination between two vowels, as measured by mismatch negativity. Adult cochlear implant users and matched normal-hearing listeners underwent electroencephalographic event-related potentials recordings in an optimum-1 oddball paradigm. A standard /a/ vowel was delivered in an acoustic free field along with stimuli having a deviant fundamental frequency (+3 and +6 semitones), a deviant first formant making it a /i/ vowel or combined deviant fundamental frequency and first formant (+3 and +6 semitones /i/ vowels). Speech recognition was assessed with a word repetition task. An analysis of variance between both amplitude and latency of mismatch negativity elicited by each deviant vowel was performed. The strength of correlations between these parameters of mismatch negativity and speech recognition as well as participants’ age was assessed. Amplitude of mismatch negativity was weaker in cochlear implant users but was maximized by variations of vowels’ first formant. Latency of mismatch negativity was later in cochlear implant users and was particularly extended by variations of the fundamental frequency. Speech recognition correlated with parameters of mismatch negativity elicited by the specific variation of the first formant. This nonlinear effect of acoustic parameters on neural discrimination of vowels has implications for implant processor programming and aural rehabilitation.
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Elias, Heidi, et Kellie Thiessen. « Management of Previable Rupture of Membranes with Prolonged Latency ». Canadian Journal of Midwifery Research and Practice 23, no 1 (22 octobre 2024) : 104–11. http://dx.doi.org/10.22374/cjmrp.v23i2.17.
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Preterm prelabor rupture of membranes at pre-viable gestations (<23–24 weeks) complicates approximately 0.1–0.8% of pregnancies. Few cases of pre-viable preterm prelabor rupture of membranes (pPPROM) have resulted in term delivery, and even fewer have experienced no complications. The case presented sustained a 21-week (147-day) latency period after confirmed pPPROM at 18+6 weeks gestation, resulting in term delivery with exceptional outcomes for both mother and baby. Expectant management with minimal intervention, due to the client’s decline of more invasive options, makes this case unique. A focused literature review was conducted to identify other rare cases of pPPROM. We were particularly interested in understanding the different approaches to managing two similar cases with prolonged latency. We highlight the variations and outcomes of expectant management of pPPROM. Despite the demonstrated benefits of recommended interventions in the expectant management of pPPROM cases, the potential side effects and outcomes of these interventions may be undesirable for patients, leading to their decline. This case underscores the importance of careful counseling regarding management options and the individualization of care based on client risk tolerance. RÉSUMÉLa rupture prématurée des membranes avant travail à des stades de gestation pré-viables (<23-24 semaines) complique environ 0,1-0,8% des grossesses. Peu de cas ont connu une rupture prématurée des membranes avant travail (RPMT), qui aboutit à un accouchement à terme, et encore moins de cas n’ont pas eu de complications. Le cas présenté a connu une période de latence de 21 semaines (147 jours) après une RPPM confirmée à 18+6 semaines de gestation et s’est soldé par un accouchement à terme avec des résultats exceptionnels pour la mère et le bébé. La gestion de l’attente avec une intervention minimale en raison du déclin de la cliente rend cette gestion de cas unique. Une analyse documentaire ciblée a été réalisée afin d’identifier d’autres cas rares de pPPROM. Nous voulions en particulier comprendre les différentes approches de la gestion de deux cas similaires avec une latence prolongée. Nous soulignons ensuite les variations et les résultats de la prise en charge attendue de la pPPROM. Malgré les avantages démontrés des interventions recommandées dans la prise en charge des cas de pPPROM, les effets secondaires potentiels et les résultats des interventions peuvent être indésirables pour les patients et entraîner leur déclin. Ce cas souligne l’importance d’un conseil attentif sur les options de prise en charge et de l’individualisation des soins en fonction de la tolérance au risque du client.
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Althoubi, Asaad, Reem Alshahrani et Hassan Peyravi. « Delay Analysis in IoT Sensor Networks ». Sensors 21, no 11 (4 juin 2021) : 3876. http://dx.doi.org/10.3390/s21113876.
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Internet of Things (IoT) devices, particularly those used for sensor networks, are often latency-sensitive devices. The topology of the sensor network largely depends on the overall system application. Various configurations include linear, star, hierarchical and mesh in 2D or 3D deployments. Other applications include underwater communication with high attenuation of radio waves, disaster relief networks, rural networking, environmental monitoring networks, and vehicular networks. These networks all share the same characteristics, including link latency, latency variation (jitter), and tail latency. Achieving a predictable performance is critical for many interactive and latency-sensitive applications. In this paper, a two-stage tandem queuing model is developed to estimate the average end-to-end latency and predict the latency variation in closed forms. This model also provides a feedback mechanism to investigate other major performance metrics, such as utilization, and the optimal number of computing units needed in a single cluster. The model is applied for two classes of networks, namely, Edge Sensor Networks (ESNs) and Data Center Networks (DCNs). While the proposed model is theoretically derived from a queuing-based model, the simulation results of various network topologies and under different traffic conditions prove the accuracy of our model.
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Young, Keith A., Marinell Smith, Tammie Rawls, Denise B. Elliott, I. Steele Russell et Paul B. Hicks. « N100 evoked potential latency variation and startle in schizophrenia ». Neuroreport 12, no 4 (mars 2001) : 767–73. http://dx.doi.org/10.1097/00001756-200103260-00031.
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Carrasco, Andres, et Stephen G. Lomber. « Neuronal activation times to simple, complex, and natural sounds in cat primary and nonprimary auditory cortex ». Journal of Neurophysiology 106, no 3 (septembre 2011) : 1166–78. http://dx.doi.org/10.1152/jn.00940.2010.
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Interactions between living organisms and the environment are commonly regulated by accurate and timely processing of sensory signals. Hence, behavioral response engagement by an organism is typically constrained by the arrival time of sensory information to the brain. While psychophysical response latencies to acoustic information have been investigated, little is known about how variations in neuronal response time relate to sensory signal characteristics. Consequently, the primary objective of the present investigation was to determine the pattern of neuronal activation induced by simple (pure tones), complex (noise bursts and frequency modulated sweeps), and natural (conspecific vocalizations) acoustic signals of different durations in cat auditory cortex. Our analysis revealed three major cortical response characteristics. First, latency measures systematically increase in an antero-dorsal to postero-ventral direction among regions of auditory cortex. Second, complex acoustic stimuli reliably provoke faster neuronal response engagement than simple stimuli. Third, variations in neuronal response time induced by changes in stimulus duration are dependent on acoustic spectral features. Collectively, these results demonstrate that acoustic signals, regardless of complexity, induce a directional pattern of activation in auditory cortex.
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Ludwig, Casimir J. H., John W. Mildinhall et Iain D. Gilchrist. « A Population Coding Account for Systematic Variation in Saccadic Dead Time ». Journal of Neurophysiology 97, no 1 (janvier 2007) : 795–805. http://dx.doi.org/10.1152/jn.00652.2006.
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During movement programming, there is a point in time at which the movement system is committed to executing an action with certain parameters even though new information may render this action obsolete. For saccades programmed to a visual target this period is termed the dead time. Using a double-step paradigm, we examined potential variability in the dead time with variations in overall saccade latency and spatiotemporal configuration of two sequential targets. In experiment 1, we varied overall saccade latency by manipulating the presence or absence of a central fixation point. Despite a large and robust gap effect, decreasing the saccade latency in this way did not alter the dead time. In experiment 2, we varied the separation between the two targets. The dead time increased with separation up to a point and then leveled off. A stochastic accumulator model of the oculomotor decision mechanism accounts comprehensively for our findings. The model predicts a gap effect through changes in baseline activity without producing variations in the dead time. Variations in dead time with separation between the two target locations are a natural consequence of the population coding assumption in the model.
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Rahman, M. Obaidur, et K. Siddique-e. Rabbani. « Distribution of Conduction Velocity (DCV) from measured F-Wave Latency for detection of cervical spondylotic radiculopathy and myelopathy (CRM) ». Bangladesh Journal of Medical Physics 7, no 1 (6 octobre 2015) : 56–65. http://dx.doi.org/10.3329/bjmp.v7i1.25260.
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In the previous work of our extended group at Dhaka, Distribution of Conduction Velocity (DCV) of motor nerve fibres in a peripheral nerve trunk was established as an approximate mirror image of Distribution of F-Latency (DFL), for which consecutive 30 to 40 F-latencies were used through multiple stimulation of a peripheral nerve trunk. Using patterns of DFL a considerable amount of experience has been built up in the detection of Cervical Spondylotic Radiculopathy and Myelopathy (CRM). In the present work we have obtained DCV directly from the Conduction Velocity (CV) values obtained from each of the F-latencies. Because of the inverse relationship between latency and velocity, a small variation to the mirror image should be present, particularly when discrete bin widths are used to obtain the frequency distribution. Therefore, one challenge was to choose an appropriate bin width while obtaining DCV directly so that the patterns can be related to those of DFL easily for the detection of CRM. To obtain DFL our extended group at Dhaka had used a bin width of 2 ms which gave good results. To choose a corresponding bin width for DCV four recognized measures of central tendency: Average of the range, Median, Mode and Mean (weighted average) were used and the resulting patterns of DCV were compared to that of DFL to determine the percentage of matches with respect to the detection of CRM. It was observed that Median gave the best DCV with 89% matches followed closely by Mode giving 83% match. The other two gave much lower values, 67% and 50%. Therefore, median value gave the best match which could be used to obtain DCV from the CV values directly, for the determination of CRM.Bangladesh Journal of Medical Physics Vol.7 No.1 2014 56-65
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Kommana, Kusuma, et Lolugu SandhyaRani. « A Survey on Challenges of Millimeter Wave Communications for Fifth-Generation Wireless Networks ». INTERANTIONAL JOURNAL OF SCIENTIFIC RESEARCH IN ENGINEERING AND MANAGEMENT 07, no 12 (23 décembre 2023) : 1–13. http://dx.doi.org/10.55041/ijsrem27765.
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Abstract-Cellular networks rely heavily on downlink beamforming; however, calculating beamformers that maximize the weighted sum rate (WSR) under power constraints is an NP-hard problem. A weighted minimum mean square error (WMMSE) algorithm variant is suggested for a MU-MISO downlink channel in order to address this trade-off between complexity and performance. This variation avoids bisection searches, eigendata compositions, and matrix inversions—all of which are challenging to implement as conventional network layers. With a reduced complexity, the suggested network architecture outperforms the WMMSE algorithm truncated to the same number of iterations and adapts well to variations in the channel distribution. Many use cases for vehicles that demand high capacity, extremely low latency, and high reliability can be made possible by 5G. To facilitate this, 5G For a MU-MISO downlink channel, a variation of the weighted minimum mean square error (WMMSE) algorithm is proposed to address this trade-off between complexity and performance. This variation avoids complex network layer implementations such as matrix inversions, eigendata compositions, and bisection searches. The suggested network architecture generalizes well to changes in the channel distribution and performs comparably to the WMMSE algorithm truncated to the same number of iterations, but at a lower complexity. Numerous automotive use cases requiring high capacity, extremely low latency, and high reliability can be made possible by 5G. 5G suggests using highly directed mm Wave system deployment and dense small cell technology to support this. To reduce the cost of signaling, however, enabling vehicular communication necessitates strong mobility management strategies. KEYWORD: Millimetre wave communications, propagation, channel measurements, channel models, MIMO, hybrid precoding, non-orthogonal multiple access (NOMA), multiple access techniques, simultaneous wireless information and power transfer (SWIPT), RF energy harvesting.
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Haseeb, Shariq, et Ahmad Faris Ismail. « Handoff latency analysis of mobile IPv6 protocol variations ». Computer Communications 30, no 4 (février 2007) : 849–55. http://dx.doi.org/10.1016/j.comcom.2006.10.010.
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Raymann, Roy J. E. M., Dick F. Swaab et Eus J. W. Van Someren. « Cutaneous warming promotes sleep onset ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 288, no 6 (juin 2005) : R1589—R1597. http://dx.doi.org/10.1152/ajpregu.00492.2004.
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Sleep occurs in close relation to changes in body temperature. Both the monophasic sleep period in humans and the polyphasic sleep periods in rodents tend to be initiated when core body temperature is declining. This decline is mainly due to an increase in skin blood flow and consequently skin warming and heat loss. We have proposed that these intrinsically occurring changes in core and skin temperatures could modulate neuronal activity in sleep-regulating brain areas (Van Someren EJW, Chronobiol Int 17: 313–54, 2000). We here provide results compatible with this hypothesis. We obtained 144 sleep-onset latencies while directly manipulating core and skin temperatures within the comfortable range in eight healthy subjects under controlled conditions. The induction of a proximal skin temperature difference of only 0.78 ± 0.03°C (mean ± SE) around a mean of 35.13 ± 0.11°C changed sleep-onset latency by 26%, i.e., by 3.09 minutes [95% confidence interval (CI), 1.91 to 4.28] around a mean of 11.85 min (CI, 9.74 to 14.41), with faster sleep onsets when the proximal skin was warmed. The reduction in sleep-onset latency occurred despite a small but significant decrease in subjective comfort during proximal skin warming. The induction of changes in core temperature (δ = 0.20 ± 0.02°C) and distal skin temperature (δ = 0.74 ± 0.05°C) were ineffective. Previous studies have demonstrated correlations between skin temperature and sleep-onset latency. Also, sleep disruption by ambient temperatures that activate thermoregulatory defense mechanisms has been shown. The present study is the first to experimentally demonstrate a causal contribution to sleep-onset latency of skin temperature manipulations within the normal nocturnal fluctuation range. Circadian and sleep-appetitive behavior-induced variations in skin temperature might act as an input signal to sleep-regulating systems.
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Balconi, Michela, et Claudio Lucchiari. « Consciousness and Emotional Facial Expression Recognition ». Journal of Psychophysiology 21, no 2 (janvier 2007) : 100–108. http://dx.doi.org/10.1027/0269-8803.21.2.100.
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Abstract. In this study we analyze whether facial expression recognition is marked by specific event-related potential (ERP) correlates and whether conscious and unconscious elaboration of emotional facial stimuli are qualitatively different processes. ERPs elicited by supraliminal and subliminal (10 ms) stimuli were recorded when subjects were viewing emotional facial expressions of four emotions or neutral stimuli. Two ERP effects (N2 and P3) were analyzed in terms of their peak amplitude and latency variations. An emotional specificity was observed for the negative deflection N2, whereas P3 was not affected by the content of the stimulus (emotional or neutral). Unaware information processing proved to be quite similar to aware processing in terms of peak morphology but not of latency. A major result of this research was that unconscious stimulation produced a more delayed peak variation than conscious stimulation did. Also, a more posterior distribution of the ERP was found for N2 as a function of emotional content of the stimulus. On the contrary, cortical lateralization (right/left) was not correlated to conscious/unconscious stimulation. The functional significance of our results is underlined in terms of subliminal effect and emotion recognition.
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Cozzi, Francesca, Luc Poncelet, Charles Michaux et Marc Balligand. « Effect of stimulus intensity on spine recorded somatosensory evoked potential in dogs ». American Journal of Veterinary Research 59, no 2 (1 février 1998) : 217–20. http://dx.doi.org/10.2460/ajvr.1998.59.02.217.
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SUMMARY Objective To investigate the effect of stimulus intensity on the characteristics of the spine recorded somatosensory evoked potentials (SEP) in dogs. Animals 11 healthy Beagles, 1 to 2 years old. Design and Procedure In 10 dogs, square-wave stimuli (0.1-ms duration, 4 Hz) were delivered through needle electrodes inserted close to the right tibial nerve at the tibiotarsal joint. A standard stimulus strength (reference effective stimulus [RS]) was established for each dog by determining the stimulus necessary to induce a maximal M wave (muscle evoked potential) in the plantar interosseus muscles. The polarity of the stimulating electrodes was then reversed, and an SEP was recorded at the level of the T13-L1 interarcuate ligament. Subsequently, stimuli at fractions (¼X, ½X) and multiples (2X, 4X) of RS were delivered. Recordings, using 10X RS stimuli, also were obtained in 2 dogs; in 1 of them, the recordings were obtained before and after curarization. In each instance, the latencies and the amplitudes of the first 3 reproducible deflections were measured and evaluated. Results The SEP waveform recorded at the T13-L1 level using RS was similar in all dogs; at least 3 deflections were recognized. Altering stimulus intensity did not significantly change latency of the first 3 peaks; conversely, amplitudes of the first 3 peaks increased (P < 0.01) when the stimulus intensity was increased from ¼X RS to 1X RS. Stimulation at 10X RS induced the recording of a large potential, which was suppressed by the curarization. Conclusion Only slight variations affect latency data through a wide range of stimulus intensities; latency measurement can be considered a robust tool in the vicinity of RS. Slight variations in the electrode position during an SEP session should not invalidate the results. Differences in the definition of the stimulus intensity among laboratories should not preclude the comparison of the results. (Am J Vet Res 1998; 59:217–220)
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Campbell, Jackie, et Massimo Leandri. « Measuring Latency Variations in Evoked Potential Components Using a Simple Autocorrelation Technique ». Computational and Mathematical Methods in Medicine 2021 (22 septembre 2021) : 1–8. http://dx.doi.org/10.1155/2021/8875445.
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Interpretation of averaged evoked potentials is difficult when the time relationship between stimulus and response is not constant. Later components are more prone to latency jitter, making them insufficiently reliable for routine clinical use even though they could contribute to greater understanding of the functioning of polysynaptic components of the afferent nervous system. This study is aimed at providing a simple but effective method of identifying and quantifying latency jitter in averaged evoked potentials. Autocorrelation techniques were applied within defined time windows on simulated jittered signals embedded within the noise component of recorded evoked potentials and on real examples of somatosensory evoked potentials. We demonstrated that the technique accurately identifies the distribution and maximum levels of jitter of the simulated components and clearly identifies the jitter properties of real evoked potential recording components. This method is designed to complement the conventional analytical methods used in neurophysiological practice to provide valuable additional information about the distribution of latency jitter within an averaged evoked potential. It will be useful for the assessment of the reliability of averaged components and will aid the interpretation of longer-latency, polysynaptic components such as those found in nociceptive evoked potentials.
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Ueno, Yuki, Mari Hirano et Atsushi Oshio. « The development of resilience in Japanese adults : A two-wave latent change model ». Health Psychology Open 7, no 1 (janvier 2020) : 205510292090472. http://dx.doi.org/10.1177/2055102920904726.
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This study examined the development of resilience in Japanese adults using a two-wave latent change model with 1284 Japanese adults (865 men, aged 20–69 years). The Bidimensional Resilience Scale was administered at both waves over a 2-year interval: January 2017 (Time 1) and January 2019 (Time 2). The results showed no significant mean-level change between Time 1 and Time 2, and relatively high stability. The latent change model indicated that changes in resilience varied significantly among individuals; however, sociodemographic variables were not significantly associated with variations in resilience. Resilience appears relatively stable in Japanese adults, despite individual variation.
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Lee, Joonyeol, Mati Joshua, Javier F. Medina et Stephen G. Lisberger. « Signal, Noise, and Variation in Neural and Sensory-Motor Latency ». Neuron 90, no 1 (avril 2016) : 165–76. http://dx.doi.org/10.1016/j.neuron.2016.02.012.
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