Comparison of surface EMG signals between electrode types, interelectrode distances and electrode orientations in isometric exercise of the erector spinae muscle

The influence of electrode type, interelectrode distance (IED) and electrode orientation on EMG signals from the paraspinal muscles was investigated. Bipolar electrodes were placed at distances 2, 3, 4, 6 and 8 cm over the erector spinae in the cranio-caudal direction ("in series") as well as in the direction perpendicular to it ("in parallel"). Ten subjects performed 5 s isometric contractions of the erector spinae at 20, 40, 60, 80 and 100% MVC by pulling upward on a handlebar attached to the floor. RMS EMG signals were analyzed for mean average amplitude (AA). Mean total power (TP) and mean median frequency (MF) of the raw EMG signal were determined using fast Fourier transform. In addition to graded loading, sustained fatiguing contractions were performed from which TP and MF were obtained. With increasing IED the AA and TP increased while MF decreased. Although a trend towards higher AA, TP and MF was found for electrodes "in series", as compared to those "in parallel", the difference never reached significance. It is concluded that consistent information about muscle activity was obtained with Miniature Biopotential Skin Electrodes and 14445C Hewlett-Packard electrodes independently from IED or orientation. Orientation "in parallel" prevented the electrodes from sliding during muscle contraction. The third tested type, electrodes developed in the Neuromuscular Research Center, Boston, proved extremely sensitive to movement.     

基于电热场耦合条件下稀土电解槽电极结构优化模拟

以3kA钕电解槽为研究模型,考虑到电热场在电解过程中的相互影响,运用COMSOL有限元模拟软件建立了的电热耦合模型,并对不同配比的电极插入深度、极间距进行仿真模拟。结果表明,在一定槽电压下,电极插入深度与极间距之间存在配比关系,配比关系影响电流和温度分布。电热场耦合后,在4.2V槽电压下,电极插入深度为220 mm、极间距75 mm时的电流效率较高,电解过程更加稳定。     

Motor unit recruitment during prolonged isometric contractions

Motor unit recruitment patterns were studied during prolonged isometric contraction using fine wire electrodes. Single motor unit potentials were recorded from the brachial biceps muscle of eight male subjects, during isometric endurance experiments conducted at relative workloads corresponding to 10% and 40% of maximal voluntary contraction (MVC), respectively. The recordings from the 10% MVC experiment demonstrated a characteristic time-dependent recruitment. As the contraction progressed both the mean number of motor unit spikes counted and the mean amplitude of the spikes increased significantly (P < 0.01). This progressive increase in spike activity was the result of a discontinuous process with periods of increasing and decreasing activity. The phenomenon in which newly recruited motor units replace previously active units is termed "motor unit rotation" and appeared to be an important characteristic of motor control during a prolonged low level contraction. In contrast to the 10% MVC experiment, there was no indication of de novo recruitment in the 40% MVC experiment. Near the point of exhaustion a marked change in action potential shape and duration dominated the recordings. These findings demonstrate a conspicuous difference in the patterns of motor unit recruitment during a 10% and a 40% MVC sustained contraction. It is suggested that there is a close relationship between intrinsic muscle properties and central nervous system recruitment strategies which is entirely different in fatiguing high and low level isometric contractions.     

A comparison of unipolar and bipolar electrograms for cardiac pacemaker sensing

Simultaneous unipolar and bipolar electrograms were recorded and compared from 49 pacemaker patients with bipolar endocardial electrodes. Average bipolar depolarization signal voltage equalled that of unipolar but showed greater variation. Bipolar and unipolar slew rates were equal in both mean and variance. The proximal pole voltage had little effect on the bipolar result in 8% of the cases, tended to cancel the tip voltage in 49% of the cases and augmented the tip voltage in 43% of the electrograms. The average bipolar R wave duration was 28% less, the T wave amplitude 34% less, and the ST-segment elevation 37% less than the unipolar values. By consistently attenuating the undersirable T waves and ST elevations, while leaving the depolarization signal unaffected, the bipolar electrode offered the advantage of a superior signal-to-noise ratio for sensing depolarization. In one case, however, the bipolar signal was so small as to cause a clinical sensing failure.     

A computer algorithm for defining the group electromyographic profile from individual gait profiles

A computer algorithm was developed to determine the group electromyographic (EMG) profile for the soleus muscle during free speed level walking. Subjects consisted of 50 adults (21 male, 29 female) with no history of musculoskeletal disease. EMG was recorded from the soleus muscle with wire electrodes, and was normalized by maximum muscle test. Two algorithms (time-adjusted mean profile (TAMP) and mean intensity profile (MIP)) were implemented to construct a group profile from identical individual EMG profiles. In addition, a grand ensemble average (GEAV) of the same individual data was performed. A high positive correlation (omega 2 > .995) was found between MIP and GEAV of EMG data. A control group was established based on mean timing and relative intensity of the individual EMG profiles. The MIP and GEAV were shown to have earlier onsets, later cessations, and extended EMG duration in comparison to control values. No significant differences were observed comparing TAMP and mean values for any measure.     

Motor control and cardiovascular responses during isoelectric contractions of the upper trapezius muscle: evidence for individual adaptation strategies

Ten females (25-50 years of age) performed isometric shoulder flexions, holding the right arm straight and in a horizontal position. The subjects were able to see the rectified surface electromyogram (EMG) from either one of two electrode pairs above the upper trapezius muscle and were instructed to keep its amplitude constant for 15 min while gradually unloading the arm against a support. The EMG electrodes were placed at positions representing a "cranial" and a "caudal" region of the muscle suggested previously to possess different functional properties. During the two contractions, recordings were made of: (1) EMG root mean square-amplitude and zero crossing (ZC) frequency from both electrode pairs on the trapezius as well as from the anterior part of the deltoideus, (2) supportive force, (3) heart rate (HR) and mean arterial blood pressure (MAP), and (4) perceived fatigue. The median responses during the cranial isoelectric contraction were small as compared to those reported previously in the literature: changes in exerted glenohumeral torque and ZC rate of the isoelectric EMG signal of -2.81% x min(-1) (P = 0.003) and 0.03% x min(-1) (P = 0.54), respectively, and increases in HR and MAP of 0.14 beats x min(-2) (P = 0.10) and 0.06 mmHg x min(-1) (P = 0.33), respectively. During the contraction with constant caudal EMG amplitude, the corresponding median responses were -2.51% x min(-1) (torque), 0.01% x min(-1) (ZC rate), 0.31 beats x min(-2) (HR), and 0.93 mmHg x min(-1) (MAP); P = 0.001, 0.69, 0.005, and 0.003, respectively. Considerable deviations from the "isoelectric" target amplitude were common for both contractions. Individuals differed markedly in response, and three distinct subgroups of subjects were identified using cluster analysis. These groups are suggested to represent different motor control scenarios, including differential engagement of subdivisions of the upper trapezius, alternating motor unit recruitment and, in one group, a gradual transition towards a greater involvement of type II motor units. The results indicate that prolonged low-level contractions of the shoulder muscles may in general be accomplished with a moderate metabolic stress, but also that neuromuscular adaptation strategies differ significantly between individuals. These results may help to explain why occupational shoulder-neck loads of long duration cause musculoskeletal disorders in some subjects but not in others.     

Muscle strain during aerial combat maneuvering exercise

BACKGROUND: Little is known about the in-flight muscular strain of fighter pilots. HYPOTHESIS: The purpose of this study was to measure fighter pilots' mean and peak muscular strain during aerial combat maneuvering exercises. The results obtained were compared against existing ergonomic recommendations. METHODS: Six pilots volunteered to serve as test subjects. Their mean age (+/- SD) was 28.5 +/- 5 yr, height 181 +/- 7 cm, and weight 75 +/- 10 kg. They performed one-to-one dog-fight exercises in the morning and in the afternoon. During the flights, the pilots' electromyographic activity (EMC) was measured from the thigh, abdomen, back, and lateral neck. The mean and peak muscular strain for each muscle was calculated as the percentage of maximal voluntary contraction (%MVC). RESULTS: The results showed that the mean muscular strain was 5.2-19.8% MVC, the strain in the lateral neck being the highest. Peak muscular strain (over 50% MVC) occurred almost only during the encounters and usually in the lateral neck. Other muscles were subjected to fewer peak strain episodes; most of these occurred in the back. At least one peak strain episode exceeding 100% MVC was recorded for every muscle studied. The highest peak strain 257% MVC, was measured in the lateral neck. This peak strain episode caused an injury to the lateral neck area, and the flight mission was discontinued. CONCLUSIONS: The mean muscular strain measured in this study was rather low. However, the strain occurring in the lateral neck and the back exceeds the ergonomic recommendations for static work. Especially in the lateral neck, and to some extent in the back, peak strain occurs frequently, in a magnitude that is well above the maximal voluntary contraction; in these areas, the peak strain presents a potential risk of injury and negative health effects. The level and frequent occurrence of peak strain episodes means that fighter pilots' muscular strength and muscular endurance, especially in the neck and shoulder area, are subjected to demands clearly higher than those of the average population.     

Enhancement of signal quality in esophageal recordings of diaphragm EMG

The crural diaphragm electromyogram (EMGdi) is recorded from a sheet of muscle, the fiber direction of which is mostly perpendicular to an esophageal bipolar electrode. The region from which the action potentials are elicited, the electrically active region of the diaphragm (EAR(di)) and the center of this region (EAR(di ctr)) may vary during voluntary contractions in terms of their position with respect to an esophageal electrode. Depending on the bipolar electrode's position with respect to the EAR(di ctr), the EMGdi is filtered to different degrees. The objectives of the present study were to reduce these filtering effects on the EMGdi by developing an analysis algorithm referred to as the "double-subtraction technique." The results showed that changes in the position of the EAR(di ctr) by +/- 5 mm with respect to the electrode pairs located 10 mm caudal and 10 mm cephalad provided a systematic variation in the EMG power spectrum center-frequency values by +/- 10%. The double-subtraction technique reduced the influence of movement of the EAR(di ctr) relative to the electrode array on EMG power spectrum center frequency and root mean square values, increased the signal-to-noise ratio by 2 dB, and increased the number of EMG samples that were accepted by the signal quality indexes by 50%.     

In vitro evaluation of the intravasal Doppler guide wire: determination of hemodynamic effects of stenoses in a flow model

PURPOSE: In a pulsatile hydraulic model, haemodynamic changes caused by stenoses were assessed using an intravascular Doppler guide wire. MATERIAL AND METHODS: In defined stenoses (25, 50, 75 and 87.5% diameter ratio), and with and without collateral flow, a 0.018 inch (0.46 mm) 12 MHz Doppler guide wire was assessed. Flow velocity measurements were taken 20 mm proximal, in, and 20 mm distal to the stenoses. Average peak velocity (APV) and ratios of pre-/poststenotic velocities and pre-/intrastenotic velocities of APV were compared with the grade of stenosis. The degree of the stenosis calculated by the ratio of the cross-sectional area, using the pre- and intrastenotic APV, was correlated with the actual stenosis. RESULTS: The intrastenotic APV increased significantly (APV proximal to the stenosis 15.15 +/- 4.5 cm/s, intrastenotic APV 134.8 +/- 130.9, p < 0.01, Wilcoxon-Mann-Whitney test). The difference between APV pre- and poststenotic was not significant (p > 0.5). Concerning the grade of stenosis the ratio APV pre-/intrastenotic and the consecutively calculated cross-sectional area stenoses was the best predictor (correlation with the known cross-sectional area stenosis r = 0.94 Pearson). CONCLUSION: Using the Doppler guide wire, APV measurements pre- and intrastenotic enable a reliable quantification of the grade of stenosis. The stenosis calculated via the cross-sectional area correlates significantly with the actual stenosis.     

Muscle fiber conduction velocity (MFCV) after fatigue in elderly subjects

The changes in muscle fiber conduction velocity (MFCV) and median frequency (MDF) during and after muscle fatigue were investigated in 9 younger (mean age: 29.3) and 7 elderly (mean age: 72.0) healthy subjects to determine if age has any effect on them. The surface EMG of the abductor digiti minimi muscle was examined at 50% of maximal voluntary contraction (MVC) during a prefatigue session. The subjects were instructed to continue applying maximal force until the force declined to 50% MVC. EMG signals were measured during brief subsequent contractions at 50% MVC until 60 minutes after fatigue as a postfatigue session. The decrement in MFCV and MDF at 50% MVC before and after fatigue was 73.4%, 67.3% in the younger and 71.2%, 66.7% in the elderly subjects, respectively. MFCV and MDF recovered to initial value after fatigue more slowly in the elderly subjects (recovery time: elderly: MFCV 6.0 min., MDF 6.0 min.; younger: MFCV 2.77 min., MDF 3.00 min.) (P < 0.05, Mann-Whitney test). The over-shooting recovery phase was recognized in both age groups, but the elderly subjects had a smaller and shorter one. The slower recovery in the elderly suggested that they possibly had less potential to recovery the membrane potential propagation, metabolic capacity and more type 1 fiber composition. The smaller and shorter overshooting in the elderly might be due to less increase of muscle swelling and/or less membrane hyperpolarization.     

The impact of critical incidents in paediatric hospitals: a review

Recent data have implicated the size of surface electrodes as an important factor affecting peripheral nerve excitation. Therefore, we studied the effects of electrode size on the basic excitatory responses and on stimulus characteristics. Four different sizes of self-adhesive surface electrodes were applied over the medial and lateral gastrocnemius muscle of 20 healthy subjects. The excitatory levels were sensory threshold, motor threshold, pain threshold, and maximally tolerated painful stimulation. Stimulus parameters included a symmetric biphasic waveform, 200 microseconds phase duration, and a pulse repetition rate of 50 pps. Amplitude was increased until the appropriate excitatory response was achieved. At this amplitude level, the computerized recording system collected data of stimulus peak current, peak voltage, and phase charge as well as isometric plantar flexion force. Repeated measure analysis of variance and Newman-Keuls post hoc tests revealed that increasing electrode size significantly decreased voltage but increased current and phase charge magnitudes. With increasing electrode area, the ratios of voltage/current decreased nonlinearly, while the ratios of charge/voltage increased nonlinearly. The comfort of stimulation for the same amount of plantar flexion force improved significantly as electrode size became larger. We concluded that electrode size affects the stimulus parameters, comfort, and force generation associated with electrically induced excitatory responses. Electrode size should be considered an integral part of the attempt to improve subject response to transcutaneous electrical stimulation.     

Influence of upper airway pressure oscillations on soft palate muscle electromyographic activity

Snoring is characterized by high-frequency (30-50 Hz) pressure oscillations (HFPO) in the upper airway (UA). The soft palate is a major oscillating structure during snoring, and soft palate muscle (SPM) activity is an important determinant of velopharyngeal patency. Consequently, we examined the effect of artificial HFPO applied to the UA on the integrated electromyographic (EMG) activity of the SPMs in 11 supine mouth-closed anesthetized (pentobarbital sodium/chloralose) dogs breathing spontaneously via a tracheostomy. The EMGs of the palatinus (Pal; n = 11), levator veli palatini (LP; n = 9), and tensor veli palatini (TP; n = 8) were monitored with intramuscular fine-wire electrodes. Peak inspiratory and peak expiratory EMG activity was measured in arbitrary units (au) as the mean of five consecutive breaths. HFPO [+/- 4.5 +/- 0.4 (SE) cmH2O; 30 Hz] applied at the laryngeal end of the isolated UA increased peak inspiratory EMG from 3.3 +/- 2.0 to 8.4 +/- 1.7 au (P < 0.05) for Pal and from 2.0 +/- 1.1 to 7.3 +/- 2.7 au (P < 0.05) for LP. For the TP, increases were evident in four dogs, but mean values for the group did not change (5.8 +/- 2.4 to 11.0 +/- 4.1 au, P = 0.5). The peak expiratory EMG did not change for any SPM (all P > 0.3). Thus HFPO applied to the UA augments inspiratory SPM activity. Reflex augmentation of SPM activity by HFPO may serve to dilate the retropalatal airway and/or stiffen the soft palate during inspiration in an attempt to stabilize UA geometry during snoring.     

Influence of posture and training on the endurance time of a low-level isometric contraction

Classically, the critical force of a muscle (the relative force below which an isometric contraction can be maintained for a very long time without fatigue) is comprised of between 15 and 20% of its maximum voluntary contraction (MVC). However, some authors believe that the value is below 10% MVC. If such is the case, signs that accompany the establishment of muscle fatigue (EMG changes, continuous increase in systolic blood pressure [SBP] and heart rate [HR]) would have to appear more rapidly and with a higher intensity if the muscle is already partially fatigued at the start of maintaining a contraction at 10% MVC. Twelve healthy untrained participants carried out two isometric contractions with the digit flexors: one (test A) began with a maximum contraction sustained for 4 min followed without interruption by a contraction at 10% MVC for 61 min; the other (test B) was a contraction maintained at 10% MVC for 65 min. For test B, after an initial increase of 4 bpm with respect to at rest, HR remained stable until the end of contraction, SBP progressively increased by 24 mm Hg in 28 min, then remained unchanged until the end, and there were no significant changes in EMG (absence of spectral deviation towards low frequencies). For test A, in spite of the initial maximum contraction, changes in the parameters being studied (total maintenance time, HR, SBP, EMG) during maintenance at 10% MVC were identical to those for test B. The results show that (1) when the number and intensity of the co-contractions are minimized by applying an appropriate posture, it is possible to sustain an isometric contraction at 10% MVC for at least 65 min without the appearance of signs of muscle fatigue; (2) the critical force of the digit flexors is higher than 10% MVC.     

Integration of excitatory postsynaptic potentials in dendrites of motoneurons of rat spinal cord slice cultures

We examined the attenuation and integration of spontaneous excitatory postsynaptic potentials (sEPSPs) in the dendrites of presumed motoneurons (MNs) of organotypic rat spinal cord cultures. Simultaneous whole cell recordings in current-clamp mode were made from either the soma and a dendrite or from two dendrites. Direct comparison of the two voltage recordings revealed that the membrane potentials at the two recording sites followed each other very closely except for the fast-rising phases of the EPSPs. The dendritic recording represented a low-pass filtered version of the somatic recording and vice versa. A computer-assisted method was developed to fit the sEPSPs with a generalized alpha-function for measuring their amplitudes and rise times (10-90%). The mean EPSP peak attenuation between the two recording electrodes was determined by a maximum likelihood analysis that extracted populations of similar amplitude ratios from the fitted events at each electrode. For each pair of recordings, the amplitude attenuation ratio for EPSP traveling from dendrite to soma was larger than that traveling from soma to dendrite. The linear relation between mean ln attenuation and distance between recording electrodes was used to map 1/e attenuations into units of distance (micron). For EPSPs with typical time course traveling from the somatic to the dendritic recording electrode, the mean 1/e attenuation corresponded to 714 micron for EPSPs traveling in the opposite direction, the mean 1/e attenuation corresponded to 263 micron. As predicted from cable analysis, fast EPSPs attenuated more in both the somatofugal and somatopetal direction than did slow EPSPs. For EPSPs with rise times shorter than approximately 2.0 ms, the attenuation factor increased steeply. Compartmental computer modeling of the experiments with biocytin-filled and reconstructed MNs that used passive membrane properties revealed amplitude attenuation ratios of the EPSP traveling in both the somatofugal and somatopetal direction that were comparable to those observed in real experiments. The modeling of a barrage of sEPSPs further confirmed that the somato-dendritic compartments of a MN are virtually isopotential except for the fast-rising phase of EPSPs. Large, transient differences in membrane potential are locally confined to the site of EPSP generation. Comparing the modeling results with the experiments suggests that the observed attenuation ratios are adequately explained by passive membrane properties alone.     

Computer model of gastric electrical stimulation

The aim of the study was to simulate gastric electrical stimulation using a computer model of gastric electrical activity and suggest a possible avenue toward reliable gastric pacing. Modeling was based on the conoidal dipole model of gastric electrical activity described earlier. It was assumed that local, nonpropagated contractions can be produced circumferentially using 4 rings of stimulating electrodes supplied with 2-sec phase-locked bipolar trains of 50 Hz, 15 V (peak to peak) rectangular voltage. Temporal and propagation organizations of gastric electrical activity described in the conoidal dipole model were used to derive the geometry of the stimulating electrodes and the time shifts for phase-locking of the electrical stimuli applied to the different circumferential electrode sets. The major assumptions and findings of the model were tested on two unconscious dogs. The model produced completely controllable simulated gastric contractions that could be propagated distally by phase-locking the stimulating voltage. The values of interelectrode distances in different rings, as well as the distances between the successive rings, were also derived. The concept of invoked circumferential contractions that are artificially propagated by phase-locking the stimulating voltage could be an avenue toward reliable gastric pacing of gastroparetic patients.     

Limits to milk flow and energy allocation during lactation of the hispid cotton rat (Sigmodon hispidus)

INTRODUCTION: Epicardial and endocardial defibrillation electrode systems affect myocardial electrophysiology and sympathetic function differently. Thus, we postulate that antiarrhythmic drugs will interact with these electrode systems differently. METHODS AND RESULTS: Defibrillation energy requirements (DER) at 20% (ED20), 50% (ED50), and 80% (ED80) success were measured at baseline and during lidocaine (10 mg/kg per hour) or D5W treatment for epicardial and endocardial electrodes. Pigs were randomized to treatment (lidocaine or D5W) and electrode system, which resulted in four experimental groups: (1) epicardial electrode + D5W; (2) epicardial electrode + lidocaine; (3) endocardial electrode + D5W; and (4) endocardial electrode + lidocaine. ED50 DER (mean +/- SEM) values at baseline for groups 1-4 were 10.6+/-1, 8.5+/-1, 12.6+/-1, and 12.3+/-1 J, respectively. DER values for groups 1 and 3 during D5W were similar to baseline. Conversely, lidocaine increased ED50 DER values from 8.5+/-1 to 13.5+/-2 J (P < 0.05) in group 2 animals (epicardial electrodes). When lidocaine was administered to group 4 animals (endocardial electrodes), however, ED50 DER values remained similar to baseline values (12.3+/-1 to 14.3+/-2 J, P = NS). Lidocaine increased ED50 DER values by 59% with the epicardial electrode system, which was significantly greater than the 16% increase with the endocardial electrode system (P < 0.05). Electrophysiologic response and electrode impedance were similar between electrode systems. CONCLUSION: Lidocaine increases DER values to a greater extent when using epicardial versus endocardial electrode system. Thus, drug-device interactions are dependent on the electrode system. These data suggest that the electrophysiologic milieu created by endocardial defibrillation mitigates the effects that lidocaine has on DER values.     

Electrodeposited iridium oxide pH electrode for measurement of extracellular myocardial acidosis during acute ischemia

In the present paper, fabrication, characterization, and physiological applications of a solid-state pH electrode are described. The pH sensing layer was based on an anodic electrodeposited iridium oxide film (AEIROF). Sputtered platinum electrodes (1 mm diameter) fabricated on flexible Kapton films or platinum wires were used as planar or cylindrical supports. Each electrode site was coated with Nafion to attenuate the interference of anionic redox species and to protect the electrode surface during in vivo measurements. Performance of the AEIROF was evaluated, for the first time, as a pH electrode and proved to have a slightly super-Nernstian response with slope of -63.5 +/- 2.2 mV/pH unit for both wire and planar sputtered platinum electrodes. Linear pH responses were obtained in the pH range 2-10. The electrodes have a working lifetime of at least 1 month with accuracy of about 0.02 pH unit and fast response time. The electrodes showed very low sensitivities for different species, such as Na+, K+, Li+, NH4+, Ca2+, Mg2+, dissolved oxygen, lactate, ascorbate, and urate, which are important for physiological applications. The electrodes were applied in extracellular pH measurements during brief regional ischemia in a swine heart and no-flow ischemia in an isolated rabbit papillary muscle. A first report on extracellular pH, K+, and lactate simultaneous measurements during no-flow ischemia using the AEIROF pH electrode and the previously described K+ and lactate electrodes is presented as well.     

Information processing, social cognition, and psychiatric rehabilitation in schizophrenia

Pattern electroretinograms are small physiologic signals that require good patient cooperation and long recording times, particularly when conditions are not optimal. Six electrodes were compared to evaluate their efficacy. Pattern electroretinograms were recorded in eight healthy volunteers to high-contrast, pattern-reversal checks (40' width) with Burian-Allen, DTL fiber, C-glide, gold foil, HK loop and skin electrodes. Raw data for 320 reversals were analyzed off-line to evaluate signal amplitude, quality, P50 and N95 peak times, artifact rate and electrical noise. Insertion time, impedance and subjective comfort were also assessed. The Burian-Allen contact lens electrode gave the largest signal and lowest impedance but was the least comfortable and had the highest artifact rate (p < 0.01). A skin electrode on the lower eyelid produced the smallest pattern electroretinogram with the poorest quality (p < 0.05). The four other electrodes were foil or fiber electrodes in contact with the tear film, conjunctiva and/or the inferior cornea. The signal from these showed only minor differences. When electrodes are compared for pattern electroretinograms recording, the foil and fiber electrodes do not differ substantially but contact lens and skin electrodes show substantial disadvantages.     

电极插入不同深度下稀土电解槽电热场耦合模拟

运用数值模拟软件COMSOL研究了不同电极插入深度下3kA钕电解槽的电热场。结果表明,电解槽槽电压随着阴阳极插入深度的递增而降低,槽体的整体温度随着阴阳极插入深度的增加而下降。结合实际生产经验与本研究结果,认为电极插入深度220mm比较适宜,且整个电解过程相对稳定,能够达到槽体电压、温度分布等方面的要求。     

Novel popout with nonsense strings: effects of predictability of string length and spatial location

The implanted system was composed of four silver ball electrodes placed in the burr hole of the skull, a reference placed subcutaneously near the nose, two electrodes for EMG, and a ground. The dural attachment was 0.1 mm in diameter. A cassette connector was placed on the back. Implanted cables between the cassette connector and all electrodes consist of twisted fine wires placed in a silicone tube 0.5 mm in diameter. The implanted electrode system weighed 0.8 g. The outlet cables were of the same materials used for implanted cables and placed in a silicone tube 1.5 mm in diameter. The impedance matching between these cables was successful and assured the minimum contamination of artifacts in the EEG recording of freely moving mice. Long-term (4-5 weeks) recording, thus, became possible without damage to the implanted materials. Monopolar recordings demonstrated the localized paroxysmal discharges during general tonic clonic convulsion in El mice. Several artifacts are presented.