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We released five adult masu salmon (Oncorhynchus masou) tagged with external transmitters to track their ascending behaviour. The signals of all specimens were recorded in the upper area of the river system. Two patterns of ascending behaviour were recognized: ascending upward immediately after release and ascending during increased river discharge. The fastest ascending speed was about 1000 m h-1 . Active movements were detected at night. The signal recording duration at each receiver for each fish was generally brief. Most fish did not stay at the pools where the receivers were installed.

The unstable temporal behavior of atrial electrical activity during persistent atrial fibrillation (persAF) might influence ablation target identification, which could explain the conflicting persAF ablation outcomes in previous studies. We sought to investigate the temporal behavior and consistency of atrial electrogram (AEG) fractionation using different segment lengths. Seven hundred ninety-seven bipolar AEGs were collected with three segment lengths (2.5, 5,and 8 s) from 18 patients undergoing persAF ablation. The AEGs with 8-s duration were divided into three 2.5-s consecutive segments. AEG fractionation classification was applied off-line to all cases following the CARTO criteria; 43% of the AEGs remained fractionated for the three consecutive AEG segments, while nearly 30% were temporally unstable. AEG classification within the consecutive segments had moderate correlation (segment 1 vs 2: Spearman’s correlation ρ = 0.74, kappa score κ = 0.62; segment 1 vs 3: ρ = 0.726, κ = 0.62; segment 2 vs 3: ρ = 0.75, κ = 0.68). AEG classifications were more similar between AEGs with 5 and 8 s (ρ = 0.96, κ = 0.87) than 2.5 versus 5 s (ρ = 0.93, κ = 0.84) and 2.5 versus 8 s (ρ = 0.90, κ = 0.78). Our results show that the CARTO criteria should be revisited and consider recording duration longer than 2.5 s for consistent ablation target identification in persAF. Electronic supplementary material The online version of this article (doi:10.1007/s11517-017-1667-1) contains supplementary material, which is available to authorized users.

Introduction Sleep is the dominant vigilance state in pre-term infants, but its regulation is still poorly understood, with no underpinning quantitative framework. In animal studies, neonatal sleep-wake characteristics follow statistical patterns, e.g. wakefulness durations exhibit an exponential distribution.1 Here we investigated whether the same holds true for pre-term human infants. Methods We recorded electroencephalography (EEG), respiratory movement, electrocardiography (ECG), and behavioural observations for up to two hours from 54 non-mechanically ventilated infants being cared for on the neonatal unit (28+2–34+1 weeks+days corrected gestational age). Data were staged as sleep or wakefulness in 30-s epochs (figure 1). We characterised i) the distribution of wakefulness durations, using the Kolmogorov-Smirnov goodness-of-fit test, and ii) the likelihood of transitioning from sleep to wakefulness during the recording, using the Kaplan-Meier estimator which takes account of censored observations, i.e. when the event of interest (wakefulness) was not captured. Results 14/54 (26%) infants cycled through wakefulness during the recording: durations ranged from 2 to 29 minutes and did not deviate significantly from an exponential distribution (D(14)=0.733, p=0.657) (figure 2 left). There is a sharp increase in the likelihood of transitioning from sleep to wakefulness when recordings increase from 93 to 96 minutes, when the estimated percentage of subjects maintaining sleep falls from 75 to 50%. Nevertheless, 25% of subjects will still be asleep at 121 minutes (figure 2 right). Discussion In pre-term infants, the durations of awakenings are exponentially distributed, as in neonatal animals.¹ The likelihood of awakening does not increase linearly with recording duration, but is gated after approximately 100 minutes, demonstrating cyclicity. Future work will build on these preliminary data to model how demographic and environmental variables (e.g. necessary painful procedures) influence the neonatal sleep-wake cycle. Reference Blumberg, et al. PNAS ( 2005)

Background: Obstructive sleep apnoea (OSA) affects 1-6% of children & is linked to respiratory, cognitive & other morbidities. Cardiorespiratory polygraphy (CRPG) & pulse oximetry (PO) aid diagnosis in UK centres. There are no guidelines on minimum recording time for these studies. Aims: To inform quality standards for optimal CRPG & PO recording duration. Methods: Data were collected from 108 children aged 0.5-18y (60 male) having CRPG with simultaneous PO at Southampton Children’s Hospital. Differences between: apnoea/hypopnoea index (AHI); oximetry desaturation index 4% (ODI4) & Delta 12s index were assessed for the first 4, 5, 6 & 7 hrs of each recording. Clinical thresholds were set at ODI4≥4/hr & AHI≥5/hr. Results: Limits of agreement between AHI, ODI4 & Delta 12 index widened with increasing duration of recordings. Median absolute AHI differences increased with time difference (4vs5hr median=0.20, CI=0.15-0.35; 4vs7hr median=0.5, CI=0.39-0.82 [p Using 7vs4hr of CRPG, 3 more children (18 vs.15) were identified with AHI≥5 (p=0.453). No more children were identified using ≥4hrs oximetry data with ODI4≥4 (n=12). Conclusion: CRPG & PO values differ with longer recording time. Based on 7 vs. 4hrs of CRPG data, 3 extra children would be diagnosed with OSA. CRPG studies of 4hrs duration may underestimate AHI & influence treatment decisions. Replication of our data will inform study duration quality standards.

Electrophysiological study that records the action potential of cardiomyocyte served as excellent tool to explore cardiology and neuroscience, disease investigation and pharmacological screening. Advances of micro/nanotechnologies promote the development of three-dimensional (3D) nanodevices to record high-quality intracellular recordings by various perforation approaches of cells, however, the complicated fabrication processes limited their large-scale manufacture. In this work, a unique nanobranched microelectrode array (NBMEA) platform is developed to achieve high-quality intracellular recording of cultured cardiomyocytes in a minimally invasive manner. The NBMEA is consisting of high aspect ratio conductive nanobranches fabricated on patterned microelectrodes combining hydrothermal growth and standard microfabrication. The 3D structure of nanobranches enables the electrode to form tight coupling with cardiomyocytes to achieve the low voltage cell electroporation and high-quality intracellular recording. The recorded intracellular action potentials of cardiomyocytes by NBMEA exhibited significant enhancement on amplitude (~5 mV), signal-to-noise ratio (SNR) (~67.47 dB), recording duration (up to 105 min), and recording yield (69.5 ± 17.8%). This NBMEA platform is a promising and powerful tool for electrophysiology that opens up new opportunities for high-quality and stable intracellular recording of cardiomyocytes.

The capture of free-ranging individuals is often needed for research, population management and health assessment. Because of its iconic and threatened species status, methods to capture koalas (Phascolarctos cinereus) receive disproportionate scrutiny. We collated data on koala capture frequency, duration held by noose and incidents from six studies of koalas in Victoria and New South Wales that all used the ‘noose and flag’ method as the primary method of capture. Adverse events occurred in less than 1% of all captures (7 of 1236). Mean capture time in three of four locations recording duration held by noose was less than five minutes, minimising the duration of distress to the koala while allowing researchers to maintain control over the animal. The exception to this was a study in far south-west Victoria where trees were tall and koalas were relatively unresponsive to flagging, resulting in a longer mean duration held by noose (11.2 minutes). The reviewed capture data of the ‘noose and flag’ method suggest that this is an effective and safe capture method, allowing for capture of multiple individuals in a short period, and suitable for most habitat types and situations.

Animal-borne accelerometers are effective tools for quantifying the kinematics of animal behaviors, such as swimming, running, and flying, under natural conditions. However, quantifying burst movements of small and agile aquatic animals (e.g., small teleost fish), such as during predatory behavior, or while fleeing, remains challenging. To capture the details of burst movements, accelerometers need to sample at a very high frequency, which will inevitably shorten the duration of the recording or increase the size of the device. To overcome this problem, we developed a high-frequency acceleration data-logger that can be triggered by a manually-defined acceleration threshold, thus allowing the selective measurement of animal burst movements. We conducted experiments under laboratory and field conditions to examine the performance of the logger. The laboratory experiment using red seabream (Pagrus major) showed that the new logger could measure the kinematics of their escape behaviors (i.e., body beat cycles and maximum acceleration values). The field experiment using free-swimming yellowtail kingfish (Seriola lalandi) showed that the loggers trigger correctly (i.e., of the 18 burst movements, 17 were recorded by the loggers). We suggest that this new logger can be applied to measure the burst movements of various small and agile animals, whose movements may be otherwise difficult to measure.

BACKGROUND: The recent development of automated cough monitors has enabled objective assessment of cough frequency. A study was undertaken to determine whether short-duration recordings( < 6 h) accurately reflect 24-h cough frequency and to investigate their responsiveness. METHODS: One hundred adults with chronic cough underwent 24-h cough frequency monitoring with the Leicester Cough Monitor and completed cough visual analog scales (VASs) and the Leicester Cough Questionnaire (LCQ). Cough recordings were analyzed using customized software to derive cough frequencies from 1 to 6 h and 24-h recordings. Responsiveness was assessed with repeat assessments following therapeutic trials. RESULTS: The median (interquartile range) 24-h cough frequency was 11.5 (5.8-26.6) coughs/h. Four hours was considered the shortest recording duration that represented 24-h cough frequency( ρ= 0.9, P ≤ .001). Median 4-h cough frequency was 16.6 (7.3-36.8) coughs/h. Both 4-h and 24-h cough frequency correlated moderately with cough VAS ( ρ= 0.49, P ≤ .01 and ρ= 0.44, P ≤ .01)and LCQ ( ρ = - 0.48, P ≤ .01; ρ = - 0.50, P ≤ .01). Four-hour cough frequency was responsive to improvements in cough severity following trials of therapy. CONCLUSIONS: Four-hour cough frequency correlates highly with 24-h cough frequency recordings and relates equally well with subjective measures in chronic cough. Short-duration cough monitoring could be a practical tool to validate the presence of cough and assess response to trials of therapy in the clinic setting.

Dense-array EEG recordings are now commonplace in research and gaining acceptance in clinical settings. Application of many sensors with traditional electrolytes is time consuming. Saline electrolytes can be used to minimize application time but recording duration is limited due to evaporation. In the present study, we evaluate a NIPAm (N-isopropyl acrylamide:acrylic acid) base electrolyte extender for use with saline electrolytes.Sensor-scalp impedances and EEG data quality acquired with the electrolyte extender are compared with those obtained for saline and an EEG electrolyte commonly used in clinical exams (Elefix).The results show that when used in conjunction with saline, electrode-scalp impedances and data across the EEG spectrum are comparable with those obtained using Elefix EEG paste.When used in conjunction with saline, the electrolyte extender permits rapid application of dense-sensor arrays and stable, high-quality EEG data to be obtained for at least 4.5 h.This is an enabling technology that will make benefits of dense-array EEG recordings practical for clinical applications.

The following on testing for gastroesophageal reflux in the 21st century contains commentaries on wireless pH monitoring; extension of pH recording duration to 48 or 96 h; extraesophageal GERD syndromes, diagnosis paradigms, and related investigating tools; off- or on-PPI reflux monitoring in the preoperative setting; and the potential influence of PPIs on reflux parameters.

Introduction Ambulatory electroencephalography (aEEG) is a useful alternative to inpatient video EEG to differentiate epileptic versus nonepileptic attacks (1, 2, 3). It is a cost-effective tool for quantifying seizure activity (4). The diagnostic yield of 24–72 h aEEG has rarely been analyzed (5, 6). Our primary aim is to measure the overall capture rate of aEEG to detect epileptiform discharges or seizures at 1, 2, or 3 days of recording. Our secondary aim is to determine how frequently positive aEEGs leads to a confirmation of diagnosis or change in management at each time interval. We suspect that the yield declines after 2 days of recording. Methods At the Stanford Comprehensive Epilepsy Center, a total of 361 adult aEEG notes were identified and retrospectively analyzed. AEEGs were recorded with 10–20 electrode placement for at least 20 h. If a patient had multiple aEEGs, only the first study was analyzed. We categorized the aEEGs into 3 durations: 1 day (20–30 h), 2 days (30–50 h), and 3 days (50–76 h). For each interval, we determined the proportion of the studies which detected epileptic seizures or discharges. For the secondary aim, we counted positive aEEGs which led to a direct confirmation of diagnosis (i.e., new diagnosis of epilepsy in a patient who was not suspected of having epilepsy or detection of events of interest). We also counted aEEGs which led to direct change in management (i.e., increased or started medications, hospital admission, or changed the presurgical workup). The Cochran-Armitage Linear Trend Test was used to ascertain significant trends. Results Among 361 consecutive adults who underwent aEEG between 2010–2017, epileptiform discharges or seizures were detected in 101 records (28%). The yield of epileptiform discharges for each time interval was 22%, 17%, and 18% for 1 day (n = 142 studies), 2 days (n = 123), and 3 days (n = 96) respectively. Seizures were detected in 11%, 7%, and 8% for 1 day, 2 days, and 3 days. There was a significantly decreasing trend in detection of newly diagnosed epilepsy (p Conclusion This study confirmed that the yield for epileptic discharges or seizures did not increase with longer recordings over 24 h. AEEGs that recorded over 24 h have higher probability of detecting nonepileptic events and are associated with increasing the anti-seizure medication dosages. Limits of the study include the retrospective design and lack of chart review on 260 patients with a negative aEEG.

Chicks beg to solicit food and care from their parents. Previous studies of nocturnally feeding Thin-billed Prions (Pachyptila belcheri) showed that chicks convey information about their condition to their parents by means of begging calls. However, those studies used tape-recorders with a limited recording duration, which precluded the recording of complete nights, so only the first begging sessions per night were analysed. Here we present data on begging call intensities and the acoustic parameters of begging elements obtained using digital voice recorders, which enabled complete nights to be recorded. Chicks used from one to five begging sessions per night. We found that the parameters of the first calling sessions did not reflect body condition, whereas the duration of begging sessions and the number of begging calls over the whole night was correlated with the chicks' body condition and the sizes of the meals delivered by the parents. The acoustic parameters of begging call elements were no...

To evaluate the effect on diagnostic performance of reducing multifocal visual-evoked potential (mfVEP) recording duration from 16 to 8 minutes per eye.Both eyes of 185 individuals with high-risk ocular hypertension or early glaucoma were studied. Two 8-minute mfVEP recordings were obtained for each eye in an ABBA order using VERIS. The first recording for each eye was compared against single run (1-Run) mfVEP normative data; the average of both recordings for each eye was compared against 2-Run normative data. Visual fields (VFs) were obtained by standard automated perimetry (SAP) within 22.3+/-27.0 days of the mfVEP. Stereo disc photographs and Heidelberg Retina Tomograph images were obtained together, within 24.8+/-50.4 days of the mfVEP and 33.1+/-62.9 days of SAP. Masked experts graded disc photographs as either glaucomatous optic neuropathy or normal. The overall Moorfields Regression Analysis result from the Heidelberg Retina Tomograph was used as a separate diagnostic classification. Thus, 4 diagnostic standards were applied in total, 2 based on optic disc structure alone and 2 others based on disc structure and SAP.Agreement between the 1-Run and 2-Run mfVEP was 90%. Diagnostic performance of the 1-Run mfVEP was similar to that of the 2-Run mfVEP for all 4 diagnostic standards. Sensitivity was slightly higher for the 2-Run mfVEP, whereas specificity was slightly higher for the 1-Run mfVEP.If higher sensitivity is sought, the 2-Run mfVEP will provide better discrimination between groups of eyes with relatively high signal-to-noise ratio (eg, early glaucoma or high-risk suspects). But if higher specificity is a more important goal, the 1-Run mfVEP provides adequate sensitivity and requires only half the test time. Considered alongside prior studies, the present results suggest that the 1-Run mfVEP is an efficient way to confirm (or refute) the extent of VF loss in patients with moderate or advanced glaucoma, particularly in those with unreliable VFs, including malingering or other "functional" forms of VF loss.

Sites of complex fractionated atrial electrograms (CFAEs) and highest dominant frequency (DF) have been proposed as critical regions maintaining atrial fibrillation (AF). This study aimed to determine the minimum electrogram recording duration that accurately characterizes CFAE or DF sites for ablation without unduly lengthening the procedure.Fourteen patients with AF undergoing catheter ablation had high-density (498 +/- 174 points) biatrial mapping performed during AF before ablation. At each point, 8-second electrograms were recorded. CFAE characterization using the NavX software provided a representation of electrogram complexity (CFE-mean). CFE-mean for each point from 7-, 6-, 5-, 4-, 3-, 2-, and 1-second subsamples were compared with the index 8-second CFE-mean. Offline spectral analysis defined DF as the frequency with greatest power, and DF of subsamples were compared with index DF. Index 8-second electrogram CFE-mean was 114 +/- 20 ms for right atria and 102 +/- 17 ms for left atria (P = 0.01); DF was 5.7 +/- 0.8 Hz for right atria and 6.0 +/- 0.8 Hz for left atria (P = 0.02). Means from shorter electrograms were nonsignificantly decreased for CFE-mean and overestimated for DF (P0.001). Mean absolute differences between subsampled and index values ranged from 3.3 to 20.1 ms for CFE-mean and 0.11 to 1.18 Hz for DF. Subsampled electrograms deviating10% from index values ranged from 2.5 to 56% for CFE-mean and 3.5 to 41% for DF. Intraclass correlation coefficients ranged from 0.992 to 0.788 for CFE-mean and 0.897 to 0.233 for DF. Unacceptable differences from index values were found with CFE-mean and DF from electrograms5 seconds.Electrograms ofor=5-second duration are required to accurately characterize CFAE and DF sites for ablation.

The P300 of the event-related potential is typically obtained for infrequent target stimuli that are embedded in a sequence of frequent irrelevant stimuli. The P300 has been suggested as a marker of high-level cognitive processing and might be useful in ophthalmology to confirm the diagnosis of a functional disorder. However, typical P300 measurements require relatively lengthy recording sessions. It would therefore be desirable to minimize the required time and to maximize the signal-to-noise ratio by finding the optimal balance between parameters such as stimulus probability and the number of target trials or the recording time. This is different from previous studies, which assessed the amplitude only. We recorded event-related potentials to visual stimuli using standard oddball paradigms with various target frequencies ranging from 2:1 (target majority) to 1:16 (massive non-target majority). We compared the signal-to-noise ratios for a fixed number of target trials as well as for a fixed total recording time and assessed effects of the immediate stimulus history. As expected, P300 amplitudes depend strongly on target infrequency. This did not reach saturation within the range tested. For a given number of target trials, the signal-to-noise ratio also increases with target infrequency. For a given recording duration, the signal-to-noise ratio is optimal around 1:8. In the 1:4 condition, the signal-to-noise ratio can be improved by excluding trials that were preceded by a target trial.

Introduction: Dominant frequency (DF) analysis of atrial electrograms has been used to characterize atrial fibrillation (AF). The aim of this study was to explore technical issues that may affect the estimation of local activation rate during AF using DF analysis. Methods and Results: Epicardial atrial electrograms recorded during AF from 10 dogs were used to evaluate the effects of unipolar versus bipolar recordings, bipolar electrode spacing, postrecording processing, far field ventricular depolarizations, ventricular template subtraction, and signal duration on DF analysis. Simulated electrograms were used to evaluate the effect of far field ventricular depolarizations and signal-to-noise ratio. DFs were compared with activation rates obtained by manual marking and the reproducibility of the DFs was evaluated. Bipolar electrograms were found to be preferable to unipolar electrograms. Preprocessing was a necessary step for bipolar signals, but also aided analysis of unipolar recordings. Ventricular far field depolarizations significantly affected DFs. Ventricular template subtraction helped DF analysis in signals with both minimal and significant ventricular components. A recording duration above 2 seconds was required for reliable DF measurements. Signal-to-noise ratios below 13 dB could also affect DF, particularly for signals with significant amplitude and frequency variation. Conclusions: Various factors affect DF analysis. Proper interpretation of DF analysis requires careful evaluation of the AF signals and robust processing techniques.

Significant advancements have been made in the development of procedures to systematically identify preferred stimuli that may function as reinforcers for persons with developmental disabilities. Indirect assessment procedures include care provider and client interviews, whereas direct assessment procedures involve systematically exposing participants to stimuli while recording their responses. These types of direct assessment procedures can be categorized as either approach-based or engagement-based. Approach-based procedures involve recording the individuals’ approach responses to stimuli presented singly or concurrently with other stimuli, whereas engagement-based procedures involve recording duration of engagement with stimuli. Although the predictive validity of indirect preference assessment procedures has yet to be established, using them in combination with direct measures of preferencemaybe most efficacious for identifying potential reinforcers. Recent research on preference assessment procedures used with persons with developmental disabilities is reviewed and the variables that one might consider prior to selecting which procedure to use in a given situation are discussed.

The pharmacological effect of the active albendazole metabolite, albendazole sulphoxide (ABZSO), depends on its sustained presence at the site of parasite location and its binding to helmith beta-tubulin. ABZSO is found in the plasma and tissues of albendazole-treated animals in two enantiomeric forms: (+)ABZSO and (-)ABZSO. Knowledge of enantioselectivity in drug action is necessary, since any difference in target proteins affinity between enantiomers may have implications on the pharmacological effect of this anthelmintic molecule. The binding of ABZSO to mammalian and helminth parasites cytosolic proteins, as well as the differential binding of both enantiomers, were studied. Cytosolic proteins from Moniezia expansa (cestode), Ascaris suum (nematode), Fasciola hepatica (trematode), rat liver and brain as well as purified porcine brain tubulin were used. Drug analysis was performed by HPLC using both C18 and chiral columns. ABZSO protein binding was quantitatively different between parasite species (4.17, 2.5 and 1.07 ng/mg for cestode, nematode and trematode, respectively); this binding to helminth cytosolic proteins was enantioselective. Enantiomeric ratios of (-)ABZSO/(+)ABZSO as a percentage were: 43/57 (Ascaris), 36/64 (Moniezia) and 91/9 (Fasciola). Conversely, the binding of ABZSO to mammalian cytosolic proteins showed no enantioselectivity. The overall binding affinity of ABZSO for mammalian cytosolic proteins was lower than that observed in helminth proteins. The characterization of the comparative binding pattern of ABZSO enantiomers to cytosolic proteins from helminth parasites and mammalian tissues may contribute to understanding the pharmacological properties of this chiral anthelmintic molecule.

Quantitative EEG is a sensitive method used to assess the effects of pharmacological substances on the central nervous system (CNS) activity. A standard technique is to measure the EEG under vigilance-controlled and resting conditions for a short duration, for example 5 min. The aim of the present study was to investigate the stability of 5-min EEG recordings. While the time course of the EEG was fairly stable during the recording session under the vigilance-controlled condition, systematic trends became apparent under the resting condition. Pharmaco-sensitivity of the EEG and its reliability increased with the recording duration. Five minutes of EEG recording seem to be sufficient and well chosen to evaluate the influence of drugs on the EEG.

Introduction The Leicester Cough Monitor (LCM) is a validated 24-h automated cough frequency monitor. Shorter recordings are more convenient for patients and take less time to analyse but their validity for assessing cough is not known. We assessed the relationship between short duration and 24-h recordings. Methods 100 patients (57 females) with chronic cough underwent 24-h ambulatory cough frequency monitoring with the LCM. Patients completed diaries to identify awake and sleep periods. Cough frequency was determined by automated analysis and presented as 24-h cough frequency (CF 24 ), awake cough frequency, sleep cough frequency, and short duration (1–6 h). Subjective cough severity was assessed by cough visual analogue scale and quality of life questionnaire (Leicester Cough Questionnaire, LCQ). The optimal short cough recording duration was determined by assessing its relationship with awake cough frequency and subjective cough severity. The responsiveness of short duration recordings was tested in 20 patients undergoing trials of therapy. Results The median (IQR) 24-h cough frequency was 11.5 (5.8 to 26.6) coughs/h, awake cough frequency 13.2 (7.6 to 37.5) coughs/h and sleep cough frequency 4.2 (1.0 to 9.2) coughs/h. 4-h cough counts correlated strongly with both awake and 24-h cough counts; r 2 =0.88 and r 2 =0.87 respectively (Abstract S117 Figure 1). There was a moderate relationship between 4-h cough frequency (CF 4 ) and LCQ and cough VAS (r=−0.48, p 4 after therapeutic trials was 0.55. Conclusions Shorter duration cough frequency recordings with the LCM accurately reflect daytime and 24-h cough frequency in patients with chronic cough. They can be used to assess daytime cough frequency and the response to trials of therapy.

An apparatus for automatically recording the duration of narcosis in mice is described. Following induction of anaesthesia the animals may be left unattended for the remainder of the experiment.

The first objective of this study was to quantify computer-identified breathing pauses in excess of two sec duration in relation to sleep states. The second objective was to examine which respiratory variables at one wk and one month of age predicted total apnea at 2 and 3 months of age. Short apnea (2 to 5 sec) were abundant in recordings of normal infants during the first one-half year of life. Apnea between 6 and 9 sec should be considered normal, whereas apnea in excess of 9 sec occurred most frequently in the first wk of life and declined sharply thereafter. Recording duration substantially affected apnea counts. Apnea at later ages could not be reliably predicted from recordings during the first wk of life.

SUMMARY To determine the effect of varying the duration of electrocardiographic recording on the detection of high premature ventricular complex (PVC) rates (30 or more PVCs/hour) and/or complex PVCs (multiform PVCs, couplets or runs) in survivors of myocardial infarction, we evaluated 175 24-hour ECG tapes with such arrhythmias for their occurrences detected in the first 1, 2, 6, 12 and 18 hours of the recordings. The first hour of recording disclosed only 47% of the tapes that, over 24 hours, showed high PVC rates or complex PVCs or both, whereas 6 hours of recording uncovered 89% of the tapes with these arrhythmias. Although a 12-hour ECG recording uncovered only 84% of the tapes with couplets and 75% of those with runs, it identified 92% of the tapes with high PVC rates and/or complex PVCs. The detection rate of high PVC rates or complex PVCs is logarithmically related to the recording duration. Seventy-eight percent of the tapes that had complex PVCs and peak PVC rates greater than 100 beats/hour, and 63% of the tapes with these complex PVCs and peak PVC rates of 30–100 beats/hour, showed these complex PVCs in the first hour. In contrast, only 22% of the tapes with complex PVCs and peak PVC rates less than 30 beats/hour were identified during the same interval. We also found that the average number of PVCs/hour was slightly higher in the first than the last 12 hours of the tapes (51 vs 43 PVCs/hour). This study demonstrates that (1) the detection rate for complex PVCs during the first hour of recording is related to the peak PVC rate, (2) a 12-hour recording during the waking period is sufficient to identify most survivors of myocardial infarction who have high PVC rates and/or complex PVCs, and (3) the detection of tapes with high PVC rates or complex PVCs can be predicted from its logarithmic relationship with the recording duration.

Heart rate variability (HRV) is non-invasive and commonly used for monitoring responses to training loads, fitness or overreaching in athletes. Yet, the recording duration for a series of RR-intervals varies from 1 to 15 min in the literature. The aim of the present work was to assess the minimum record duration to obtain reliable HRV results. RR-intervals from 159 orthostatic tests (7min supine, SU, followed by 6 min standing, ST) were analyzed. Reference windows were 4 min in SU (min 3 to 7) and 4 min in ST (min 9 to 13). Those windows were subsequently divided and the analyses were repeated on eight different fractioned windows: the first min (0-1), the second min (1-2) the third min (2-3), the fourth min (3-4), the first two min (0-2), the last two min (2-4), the first three min (0-3) and the last three min (1-4). Correlation and Bland & Altman statistical analyses were systematically performed. The analysis window could be shortened to 0-2 instead of 0-4 for RMSSD only, whereas the 4-min window was necessary for LF and total power. Since there is a need for 1 min of baseline to obtain a steady signal prior the analysis window, we conclude that studies relying on RMSSD may shorten the windows to 3 min (= 1+2) in SU or seated position only and to 6 min (=1+2 min SU plus 1+2 min ST) if there is an orthostatic test. Studies relying on time- and frequency-domain parameters need a minimum of 5 min (=1+4) min SU or seated position only but require 10 min (=1+4 min SU plus 1+4 min ST) for the orthostatic test.

The aim of this study was to investigate the use of inexpensive and easy-to-use hydrogel “marble” electrodes for the recording of electrical potentials of the human visual cortex using visual evoked potentials (VEPs) as example. Top hat-shaped holders for the marble electrodes were developed with an electrode cap to acquire the signals. In 12 healthy volunteers, we compared the VEPs obtained with conventional gold-cup electrodes to those obtained with marble electrodes. Checkerboards of two check sizes—0.8° and 0.25°—were presented. Despite the higher impedance of the marble electrodes, the line noise could be completely removed by averaging 64 single traces, and VEPs could be recorded. Linear mixed-effect models using electrode type, stimulus, and recording duration revealed a statistically significant effect of the electrode type on only VEP N75 peak latency (mean ± SEM: 1.0 ± 1.2 ms) and amplitude (mean ± SEM: 0.8 ± 0.9 µV) The mean amplitudes of the delta, theta, alpha, beta, and gamma frequency bands of marble electrodes were statistically significantly different and, on average, 25% higher than those of gold-cup electrodes. However, the mean amplitudes showed a statistically significant strong correlation (Pearson’s r = 0.8). We therefore demonstrate the potential of the inexpensive and efficient hydrogel electrode to replace conventional gold-cup electrodes for the recording of VEPs and possibly other recordings from the human cortex.

Le Sacre du printemps constitue une oeuvre clé pour l’histoire de l’enregistrement et pour la musicologie de l’interprétation. Igor Stravinski considérait ses enregistrements comme établissant un modèle d’interprétation faisant autorité, mais c’est un fait connu qu’il ne respecte pas ses propres indications de tempo et fait un usage plus ou moins important du rubato. Ces incertitudes sur les tempi ont créé le doute et ont ouvert un espace de liberté pour les interprètes. Cet article s’est donné pour objectif d’examiner à nouveaux frais l’évolution de l’interprétation du Sacre des points de vue de la durée et du tempo. Le recours à un vaste corpus de 96 versions discographiques enregistrées entre 1929 et 2019 a permis d’obtenir une représentation claire de l’évolution de l’interprétation de l’oeuvre sur 90 ans, de dégager la marge de liberté dans les choix des tempi et d’établir une cartographie des styles d’interprétation., The Rite of Spring is a key work for the history of recording and for the musicology of performance. Stravinsky regarded his recordings as establishing an authentic model of interpretation, but it is a well-known fact that he does not respect his own tempo indications and makes use of rubato to varying degrees. These uncertainties about tempi have created doubt and opened a space of freedom for conductors. This article aims to take a fresh look at how the interpretation of the Rite evolved, from the point of view of duration and tempo. Using a vast corpus of 96 discographic versions recorded between 1929 and 2019 has made it possible to obtain a clear representation of the evolution of the work’s interpretation over 90 years, to identify the margin of freedom in the choice of tempi, and to establish a cartography of the interpretive styles.