Wave Amplitude Changes Research Articles

QEEG Measures of Attentional and Memory Network Functions in Medical Students: Novel Targets for Pharmacopuncture to Improve Cognition and Academic Performance.

ObjectivesAttentional and memory functions are important aspects of neural plasticity that, theoretically, should be amenable to pharmacopuncture treatments. A previous study from our laboratory suggested that quantitative electroencephalographic (qEEG) measurements of theta/beta ratio (TBR), an index of attentional control, may be indicative of academic performance in a first-semester medical school course. The present study expands our prior report by extracting and analyzing data on frontal theta and beta asymmetries. We test the hypothesis that the amount of frontal theta and beta asymmetries (fTA, fBA), are correlated with TBR and academic performance, thereby providing novel targets for pharmacopuncture treatments to improve cognitive performance.MethodsTen healthy male volunteers were subjected to 5–10 min of qEEG measurements under eyes-closed conditions. The qEEG measurements were performed 3 days before each of first two block examinations in anatomy-physiology, separated by five weeks. Amplitudes of the theta and beta waveforms, expressed in μV, were used to compute TBR, fTA and fBA. Significance of changes in theta and beta EEG wave amplitude was assessed by ANOVA with post-hoc t-testing. Correlations between TBR, fTA, fBA and the raw examination scores were evaluated by Pearson’s product-moment coefficients and linear regression analysis.ResultsfTA and fBA were found to be negatively correlated with TBR (P<0.03, P<0.05, respectively) and were positively correlated with the second examination score (P<0.03, P=0.1, respectively).ConclusionSmaller fTA and fBA were associated with lower academic performance in the second of two first-semester medical school anatomy-physiology block examination. Future studies should determine whether these qEEG metrics are useful for monitoring changes associated with the brain’s cognitive adaptations to academic challenges, for predicting academic performance and for targeting phamacopuncture treatments to improve cognitive performance.

T wave and ST segment amplitude changes in the supine and standing electrocardiograms of children with orthostatic hypertension and their clinical significance

To examine the changes in T wave and ST segment amplitude in the supine and standing electrocardiograms (ECG) of children with orthostatic hypertension (OHT) and to determine their clinical significance. A total of 49 children with OHT were included in the OHT group. Forty-three age- and sex-matched healthy children were included in the control group. Heart rate and T wave and ST segment amplitude were measured in both groups. T wave amplitude and ST segment amplitude in supine ECG were compared with those in standing ECG within each group. The differences in supine vs standing T wave amplitude and ST segment amplitude were compared between the OHT and control groups. In the control group, T wave amplitude in leads aVR, V1, and V4-V6 were significantly lower in standing ECG than in supine ECG (P<0.05); ST segment amplitude in leads V4 and V5 were significantly higher in standing ECG than in supine ECG (P<0.05). In the OHT group, T wave amplitude in leads II, aVR, aVF, and V4-V6 were significantly lower in standing ECG than in supine ECG (P<0.05); ST segment amplitude in lead II was significantly higher in standing ECG than in supine ECG (P<0.05). The differences in T wave amplitude in lead II and V6 between supine and standing ECG were significantly higher in the OHT group than in the control group (P<0.05). Difference in T wave amplitude in lead V6 between supine and standing ECG was a significant diagnostic marker for OHT (P<0.05). This marker had 72.10% sensitivity and 57.10% specificity for the diagnosis of OHT at the optimal cut-off value of 0.105 mV. Difference in T wave amplitude in lead V6 between supine and standing ECG has certain diagnostic value for OHT.

Experimental Relationship Between Compressional Wave Attenuation and Surface Strains in Brittle Rock

AbstractLinear ultrasonic testing (LUT) has been extensively used as a tool for the evaluation of damage processes in various materials ranging from synthetic metals to natural geomaterials, such as rocks. A key limitation of LUT‐based damage studies to date is the lack of explicit evidence used in associating material damage with the changes in measured LUT attributes (e.g., ultrasonic wave amplitude and velocity). In this study, the evolution of the full‐field strains in brittle rock specimens (Lyons sandstone) subjected to failure are analyzed in real time and linked with the changes in the ultrasonic wave amplitude in localized areas illuminated by ultrasonic beams, termed as the ultrasonic image areas. The noncontact optical full‐field displacement measurement method of 2‐D digital image correlation is implemented in combination with the LUT procedure to continuously track changes in the ultrasonic wave amplitude with the evolution of strains across the surface of the uniaxially loaded intact rock specimens. The ultrasonic amplitude showed near‐linear correlation with the intensity of inelastic tensile strain recorded in the rock specimens. The results from the study corroborate that the ultrasonic changes are in fact influenced by the regions of tensile cracking, which is the primary inelastic deformation mechanism in brittle rocks.

Photoplethysmography-Based Continuous Systolic Blood Pressure Estimation Method for Low Processing Power Wearable Devices

Regardless of age, it is always important to detect deviations in long-term blood pressure from normal levels. Continuous monitoring of blood pressure throughout the day is even more important for elderly people with cardiovascular diseases or a high risk of stroke. The traditional cuff-based method for blood pressure measurements is not suitable for continuous real-time applications and is very uncomfortable. To address this problem, continuous blood pressure measurement methods based on photoplethysmogram (PPG) have been developed. However, these methods use specialized high-performance hardware and sensors, which are not available for common users. This paper proposes the continuous systolic blood pressure (SBP) estimation method based on PPG pulse wave steepness for low processing power wearable devices and evaluates its suitability using the commercially available CMS50FW Pulse Oximeter. The SBP estimation is done based on the PPG pulse wave steepness (rising edge angle) because it is highly correlated with systolic blood pressure. The SBP estimation based on this single feature allows us to significantly reduce the amount of data processed and avoid errors, due to PPG pulse wave amplitude changes resulting from physiological or external factors. The experimental evaluation shows that the proposed SBP estimation method allows the use of off-the-shelf wearable PPG measurement devices with a low sampling rate (up to 60 Hz) and low resolution (up to 8-bit) for precise SBP measurements (mean difference MD = −0.043 and standard deviation SD = 6.79). In contrast, the known methods for continuous SBP estimation are based on equipment with a much higher sampling rate and better resolution characteristics.

Slowing of Alpha Waves on EEG, an Early Marker of Minimal Hepatic Encephalopathy

Introduction: Minimal Hepatic Encephalopathy (MHE) is the mildest form of spectrum of Hepatic Encephalopathy (HE) which remains undiagnosed due to lack of awareness. MHE has a negative effect on patient's daily functioning due to cognitive impairment. Electro-Encephalo-Gram (EEG) and Mini Mental State Examination (MMSE) are useful in early diagnosis and follow up of MHE. Aim: To study evidence of MHE in patients with liver cirrhosis by psychometric tests and also its correlation with EEG changes. Materials and Methods: The study was carried out as a prospective case control study of 70 patients diagnosed with Cirrhosis of liver, over a period of two years in accordance with European Association for the Study of the Liver (EASL) and Asociacion Latinoamericana parael Estudio del Higado (ALEH) criteria with MMSE score &gt;24 and were diagnosed as Minimal Hepatic Encephalopathy if 2 out of 3 psychometric tests were abnormal EEG was performed in them and was compared with 70 healthy controls. Results: Study showed male predominance (90%) with mean age of 45.49 ± 11.76. Alcohol related cirrhosis (70%) was found to be more common than HBV (8.57%) and HCV (2.86%) infection related cirrhosis. Pedal edema, icterus, pallor and ascites were the most common presenting manifestations. Most cirrhotic cases (80%) were under Child Pugh Class-A. On USG of abdomen all cases had Coarse echotexture and nodular surface of liver among them 11 cases had Hepatomegaly, 10 cases had splenomegaly, 42 cases had ascites and 24 cases had increased portal venous diameter of mean size 14.02 ± 0.48 mm. MMSE score of all selected cirrhotic cases was &gt;24. Psychometric Tests i.e. Number Connection Test-A, Number Connection Test-B and Line tracing test were performed in all selected cirrhotic cases and they were not able to perform it within designated time. All cases were subjected to EEG and compared with equal number of comparable healthy controls, which shows change in frequency and amplitude of Alpha wave which was highly significant whereas no significant changes of frequency and amplitude of Beta, Theta and Delta waves between cases and controls. Conclusion: There is significant changes in alpha wave frequency and amplitude in patients with minimal hepatic encephalopathy.

Reversible Functional Changes Evoked by Anodal Epidural Direct Current Electrical Stimulation of the Rat Auditory Cortex.

Rat auditory cortex was subjected to 0.1 mA anodal direct current in seven 10-min sessions on alternate days. Based on the well-known auditory cortex control of olivocochlear regulation through corticofugal projections, auditory brainstem responses (ABRs) were recorded as an indirect test of the effectiveness and reversibility of the multisession protocol of epidural stimulation. Increases of 20–30 dB ABR auditory thresholds shown after epidural stimulation reverted back to control levels 10 min after a single session. However, increases in thresholds revert 4 days after multisession stimulation. Less changes in wave amplitudes and threshold shifts were shown in ABR recorded contralaterally to the electrically stimulated side of the brain. To assess tissue effects of epidural electric stimulation on the brain cortex, well characterized functional anatomical markers of glial cells (GFAP/astrocytes and Iba1/microglial cells) and neurons (c-Fos) were analyzed in alternate serial sections by quantitative immunocytochemistry. Restricted astroglial and microglial reactivity was observed within the cytoarchitectural limits of the auditory cortex. However, interstitial GFAP overstaining was also observed in the ventricular surface and around blood vessels, thus supporting a potential global electrolytic stimulation of the brain. These results correlate with extensive changes in the distribution of c-Fos immunoreactive neurons among layers along sensory cortices after multisession stimulation. Quantitative immunocytochemical analysis supported this idea by showing a significant increase in the number of positive neurons in supragranular layers and a decrease in layer 6 with no quantitative changes detected in layer 5. Our data indicate that epidural stimulation of the auditory cortex induces a reversible decrease in hearing sensitivity due to local, restricted epidural stimulation. A global plastic response of the sensory cortices, also reported here, may be related to electrolytic effects of electric currents.

Maximum Power Control of Gyroscopic Wave Energy Converter

A new type of wave energy converter device, gyroscopic wave energy converter (GWEC) based on gyroscopic precession principle, is proposed in this paper. The dynamic model of the device is established, and a variable load maximum power point tracking (MPPT) method is adopted to achieve the goal of keeping the system near the maximum power when the wave amplitude changes. The maximum power point of the circuit is found by perturbation and observation method and incremental conductance method to form a specified PWM wave, which can control the switching on and off, then change the load of the circuit, and realizes the maximum power tracking of the system. Compared with the simulation results, the two methods have their own characteristics, but they can basically adjust the equivalent load adaptively with the change of wave amplitude, and achieve the maximum power output of the circuit.

EMG in piriformis syndrome diagnosis: Reliability of peroneal H-reflex according to results obtained after surgery, Botox injection and medical treatment

Diagnosing piriformis syndrome (PS) throughout the past decades was not that easy, however peroneal H-reflex was proved as reliable test for PS with the change in wave amplitude and delay in conduction as parameters for diagnosis. We interpreted these parameters according to treatment’s results carried out for patients presenting clinical PS, aiming to define a threshold value for peroneal H-reflex delay to accurately diagnose. A retrospective mono-centric review of 27 patients, 9 females and 18 males, aged 22–65 years, benefited from peroneal H-reflex test and treated for clinical PS. These patients were classified into 3 groups according to treatment modality they received: 11 patients underwent surgical treatment, 7 patients underwent Botox injections (4 of them benefited from surgery later on) and 9 patients received pharmacological treatment. From 11 operated patients with 4 < delay < 9 ms, 10 had complete improvement and 1 remained in pain. For 7 patients having injection of Botox 100–300 IU, with 5 < delay < 7 ms had a transient recovery, 4 of them have benefited later from surgery, the 3 others reproved pain. Between 9 patients who have declined invasive treatment, 7 patients with 4 < delay < 10 ms didn’t demonstrate any improvement after medical treatment and are suspected of PS, 2 others with delay < 4 ms recovered from a non-confirmed PS. A threshold value to diagnose PS was reached through peroneal H-reflex delay ranges, classified as: high with a delay > 5 ms, moderate: 4 < delay < 5 ms and poor: <4 ms.

Evolution of Elastic Wave Velocities and Amplitudes During Triaxial Deformation of Aji Granite Under Dry and Water‐Saturated Conditions

AbstractElastic wave velocities and amplitudes in fine‐grained Aji granite are measured during a series of deformation experiments under both dry and fluid‐saturated conditions, where compressional and shear waves traveled in a direction normal to the compressional axis, and shear wave was polarized normal to the compressional axis. In the early stages of deformation, both VP and VS increase slightly due to closure of preexisting cracks and then decrease due to nucleation and crack growth as the sample approaches failure. During deformation, the different sensitivities of compressional and shear waves to fluid‐filled cracks mean that the ratio VP/VS tends to increase for wet experiments and decrease for dry experiments prior to failure. The relative changes in elastic wave amplitudes are also related to deformation and fluid saturation: amplitude decreases at high differential stresses due to the opening of cracks oriented subparallel to the axis of maximum compression, whereas a relatively minor change in amplitude was observed under fluid‐saturated conditions. Thus, the changes in velocity and amplitude during the deformation experiments are linked to crack development and geometry. However, this sensitivity differs between dry and fluid‐saturated conditions. The monitoring of fluid injection volumes during fluid‐saturated experiments shows that decreasing elastic wave velocities and amplitudes coincide with increasing fluid injection. These systematic relationships among elastic wave velocity, amplitude, crack development, and fluid saturation suggest that understanding changes in seismic wave properties can offer significant insights into the temporal changes in the structure of fracture zones.

Modeling studies of tidal dynamics and the associated responses to coastline changes in the Bohai Sea, China

Over the past 30 years, reclamation projects and related changes have impacted the hydrodynamics and sediment transport in the Bohai Sea. Three-dimensional tidal current models of the Bohai Sea and the Yellow Sea were constructed using the MIKE 3 model. We used a refined grid to simulate and analyze the effects of changes in coastline, depth, topography, reclamation, the Yellow River estuary, and coastal erosion on tidal systems, tide levels, tidal currents, residual currents, and tidal fluxes. The simulation results show that the relative change in the amplitude of the half-day tide is greater than that of the full-day tide. The changes in the tidal amplitudes of M2, S2, K1, and O1 caused by coastline changes accounted for 27.76–99.07% of the overall change in amplitude from 1987 to 2016, and water depth changes accounted for 0.93–72.24% of the overall change. The dominant factor driving coastline changes is reclamation, accounting for 99.55–99.91% of the amplitude changes in tidal waves, followed by coastal erosion, accounting for 0.05–0.40% of the tidal wave amplitude changes. The contribution of changes in the Yellow River estuary to tidal wave amplitude changes is small, accounting for 0.01–0.12% of the amplitude change factor. The change in the highest tide level (HTL) is mainly related to the amplitude change, and the correlation with the phase change is small. The dominant factor responsible for the change in the HTL is the tide amplitude change in M2, followed by S2, whereas the influence of the K1 and O1 tides on the change in the HTL is small. Reclamation resulted in a decrease in the vertical average maximum flow velocity (VVAM) in the Bohai Sea. Shallower water depths have led to an increase in the VVAM; deeper water depths have led to a decrease in the maximum flow velocity. The absolute value of the maximum flow velocity gradually decreases from the surface to the bottom, but the relative change value is basically constant. The changes in the tidal dynamics of the Bohai Sea are proportional to the degree of change in the coastline. The maximum and minimum changes in the tidal flux appear in Laizhou Bay (P-LZB) and Liaodong Bay (P-LDB), respectively. The changes in the tidal flux are related to the change in the area of the bay. Due to the reduced tidal flux, the water exchange capacity of the Bohai Sea has decreased, impacting the ecological environment of the Bohai Sea. Strictly controlling the scale of reclamation are important measures for reducing the decline in the water exchange capacity of the Bohai Sea and the deterioration of its ecological environment.

The Numerical Simulation of Sector Cement Missing Characteristic Wave in Vertical Well

Numerical simulate the sound field of the Ⅱ interface sector cement missing in the vertical well. And study the influencing factors of the characteristic wave amplitude and travel time by the sector missing angle, the fluid ring thickness, and the formation media and so on. It is considered that the sector missing angle has a great influence on the amplitude of the characteristic wave, but has little influence on the first wave travel time. As the sector missing angle increases, the characteristic wave amplitude also increases. When the thickness of the fluid ring is greater than a certain value (5mm), the thickness of the fluid ring increases. The amplitude of the characteristic wave increases gradually when the sector missing angle is the same. From the influencing factors of characteristic wave amplitude change, we can see that the angle change of sector cement missing is equivalent to the fluid ring thickness change.

3-10-01. Intraoperative detection using transcranial electrical stimulated muscle evoked potentials (TcMsEP) of postoperative upper extremity palsies after cervical spine surgery – The difference between C5 and C7 palsies

Although intraoperative TcMsEP monitoring is useful to detect postoperative palsy following spine surgeries, a controversy remains in the detection of segmental upper extremity palsies. In this study, we investigated the difference between C5 and C7 palsies after cervical spine surgeries that were detected by TcMsEP monitoring. This study included 5 patients with C5 palsies and 3 with C7 palsies. TcMsEP monitoring was performed in the biceps brachii, triceps brachii, abductor digiti minimi, and abductor halluces. A more than 50% decrease in the wave amplitude was defined as an alarm criterion. Postoperative C5 palsies were defined as muscle weakness in deltoid and biceps and C7 palsies were defined as muscle weakness in triceps. C5 palsy cases showed segmental wave decrease in biceps and triceps waves although there was no palsy in triceps muscle. In contrast, C7 palsy cases showed segmental wave decrease in Triceps without no wave decrease in the other muscles. Our results showed unique difference of wave amplitude changes between C5 and C7 palsies, especially in the triceps muscles. We speculated that the difference of innervation of the biceps and triceps muscles might cause the contradiction. Further examination will be necessary.

Long-Term Synergistic Interaction of Cisplatin- and Noise-Induced Hearing Losses.

Past experiments in the literature have shown that cisplatin interacts synergistically with noise to create hearing loss. Much of the previous work on the synergistic interaction of noise and cisplatin tested exposures that occurred very close together in time. The present study assessed whether rats that have been exposed to cisplatin continue to show increased susceptibility to noise-induced hearing loss months after conclusion of the cisplatin exposure. Thirty-two Fischer 344/NHsd rats were exposed to one of five conditions: (1) cisplatin exposure followed by immediate cochlear tissue harvest, (2) cisplatin exposure and a 20-week monitoring period before tissue harvest, (3) cisplatin exposure followed immediately by noise exposure, (4) cisplatin exposure followed by noise exposure 16 weeks later, and (5) noise exposure without cisplatin exposure. The cisplatin exposure was an 8-week interval in which cisplatin was given every 2 weeks. Cochlear injury was evaluated using auditory brainstem response thresholds, P1 wave amplitudes, and postmortem outer hair cell counts. The 8-week cisplatin exposure induced little threshold shift or P1 amplitude loss, and a small lesion of missing outer hair cells in the basal half of the cochlea. The rats exposed to noise immediately after the cisplatin exposure interval showed a synergistic interaction of cisplatin and noise. The group exposed to noise 16 weeks after the cisplatin exposure interval also showed more severe threshold shift and outer hair cell loss than control subjects. The controls exposed to cisplatin and monitored for 20 weeks showed little threshold shift or outer hair cell loss, but did show P1 wave amplitude changes over the 20-week monitoring period. The results from the groups exposed to cisplatin followed by noise, combined with the findings from the cisplatin- and noise-only groups, suggest that the cisplatin induced cochlear injuries that were not severe enough to result in threshold shift, but left the cochlea in a state of heightened susceptibility to future injury. The heightened susceptibility to noise injury was still present 16 weeks after the conclusion of the cisplatin exposure.

Ranolazine reduces atrial fibrillatory wave frequency.

Antiarrhythmic medications for the treatment of atrial fibrillation (AF) have limited efficacy and rare but potentially life-threatening side effects. Ranolazine is an antianginal agent that may have antiarrhythmic activity in AF. Using the Duke Enterprise Data Unified Content Explorer database, we analysed a cohort of AF patients on ranolazine. Patients served as their own historic control. Electrocardiograms (ECGs) were analysed before and after ranolazine initiation to determine the effect of ranolazine on dominant frequency (DF), f-wave amplitude, and organizational index (OI). We identified 15 patients with ECGs in AF before and after ranolazine. Ranolazine was associated with lower DF by an average of 10% (5.10 ± 0.74 vs. 5.79 ± 0.96 Hz, P = 0.04) but not with changes in OI (0.47 ± 0.11 vs. 0.50 ± 0.12, P = 0.71) or amplitude (0.47 ± 0.43 vs. 0.41 ± 0.40 mV, P = 0.82). Ranolazine was also associated with lower DF in patients (n = 10) not on concomitant antiarrhythmic therapy (5.25 ± 0.78 vs. 6.03 ± 0.79 Hz, P = 0.04). Ranolazine is associated with lower AF DF but no change in OI or fibrillatory wave amplitude. Prospective trials are needed to evaluate ranolazine's potential as a novel antiarrhythmic drug for AF.

Case History: Using time‐lapse vertical seismic profiling data to constrain velocity–saturation relations: the Frio brine pilot CO2 injection

ABSTRACTCO2 sequestration projects benefit from quantitative assessment of saturation distribution and plume extent for field development and leakage prevention. In this work, we carry out quantitative analysis of time‐lapse seismic by using rock physics and seismic modelling tools. We investigate the suitability of Gassmann's equation for a CO2 sequestration project with 1600 tons of CO2 injected into high‐porosity, brine‐saturated sandstone. We analyze the observed time delays and amplitude changes in a time‐lapse vertical seismic profile dataset. Both reflected and transmitted waves are analyzed qualitatively and quantitatively. To interpret the changes obtained from the vertical seismic profile, we perform a 2.5D elastic, finite‐difference modelling study. The results show a P‐wave velocity reduction of 750 m/s in the proximity of the injection well evident by the first arrivals (travel‐time delays and amplitude change) and reflected wave amplitude changes. These results do not match with our rock physics model using Gassmann's equation predictions even when taking uncertainty in CO2 saturation and grain properties into account. We find that time‐lapse vertical seismic profile data integrated with other information (e.g., core and well log) can be used to constrain the velocity–saturation relation and verify the applicability of theoretical models such as Gassmann's equation with considerable certainty. The study shows that possible nonelastic factors are in play after CO2 injection (e.g., CO2–brine–rock interaction and pressure effect) as Gassmann's equation underestimated the velocity reduction in comparison with field data for all three sets of time‐lapse vertical seismic profile attributes. Our work shows the importance of data integration to validate the applicability of theoretical models such as Gassmann's equation for quantitative analysis of time‐lapse seismic data.

Therapeutic Value of Ginkgo biloba Extract EGb 761® in an Animal Model (Meriones unguiculatus) for Noise Trauma Induced Hearing Loss and Tinnitus.

Noise induced hearing loss (NIHL) is a common disease in modern societies and may lead to maladaptations within the auditory system that finally result in subjective tinnitus. Available therapies may only alleviate the symptoms rather than restore normal hearing. In a previous study we demonstrated that the prophylactic application of Ginkgo biloba extract EGb 761® significantly reduces NIHL and tinnitus development in our Mongolian gerbil (Meriones unguiculatus) animal model. Here, we tested whether the application of EGb 761® has beneficial effects after the formation of permanent NIHL and tinnitus. To this end we monitored the therapeutic effects of EGb 761® on noise trauma-induced changes in signal processing within the auditory system of our animal model by behavioral (acoustic startle response, ASR) and electrophysiological approaches (auditory brainstem responses, ABR). We found that–in contrast to vehicle–three weeks of daily oral EGb 761® treatment (100 mg/kg body weight) led to a restoration of hearing thresholds back to pre-trauma conditions. In addition, all 9 animals that displayed behavioral signs of subjective tinnitus showed improvement, with 7 of them showing complete relief of tinnitus symptoms during the time of EGb 761® treatment. After discontinuation of EGb 761® treatment, tinnitus related behavior reappeared in all but one of these animals while auditory thresholds remained restored. A detailed analysis of ABR waves revealed that EGb 761® treatment did not simply change auditory processing back to pre-trauma conditions, but led to subtle changes of ABR wave amplitude and latency at different levels of the auditory pathway, with an overall increase of response to low stimulus intensities and a decrease at high intensities. The functional relevance of these changes may be the observed improvement of hearing thresholds while at the same time suppression of responses to high stimulus intensities may point to a global inhibitory mechanism that counteracts tinnitus.

Variability of nonlinear internal waves in the South China Sea affected by the Kuroshio and mesoscale eddies

AbstractLong‐term observations of nonlinear internal waves in the South China Sea reveal seasonal to interannual variability. During two selected segments of inverted echo sounder observations, tidal forcing in Luzon Strait is almost identical, but the observed amplitudes of nonlinear internal waves in the South China Sea are very different. The effects of the Kuroshio and mesoscale eddies, reproduced by HYbrid Cooridnate Ocean Model (HYCOM) reanalysis simulation, are then investigated. The Kuroshio can enhance the zonal tilt of the thermocline and induce intruding flow in Luzon Strait. During the two selected segments, different thermocline slopes did not significantly change the internal tide generation, but the intruding flow may result in a 11% difference in the amplitude of generated M2 internal tides. During the two selected segments, mesoscale eddies appeared on the path of internal wave propagation, a cold eddy in one case and a warm one in the other. The eddies changed local stratification and induced additional background currents, thus affecting the nonlinear evolution of internal tides. In addition, wave front steering due to the mesoscale eddies dramatically affected the observed amplitude changes of the nonlinear internal waves: the edge, rather than the center, of the nonlinear internal wave front passed through the observational stations, resulting in reduced amplitude in the observations.

Modified limb lead ECG system effects on electrocardiographic wave amplitudes and frontal plane axis in sinus rhythm subjects.

Objective:Modified Limb Lead (MLL) ECG system may be used during rest or exercise ECG, or atrial activity enhancement. Because of modification in the limb electrode placement, changes are likely to happen in ECG wave amplitudes and frontal plane axis, which may alter the clinical limits of normality and ECG diagnostic criteria. The present study investigated the effects of the modified limb electrode position on the electrocardiographic waveforms, ST segment amplitudes (STa) and frontal plane axis.Methods:The observational study included sixty sinus rhythm subjects of mean age 38.85±8.76 (SD) in the range 25 to 58 years. In addition to 12-lead ECG, MLL ECG was recorded with, the RA electrode placed in the 3rd right intercostal space to the right of the parasternal line, the LA electrode placed in the 5th right intercostal space to the right of the mid-clavicular line and the LL electrode placed in the 5th right intercostal space on the mid-clavicular line.Results:The modification produced profound changes in ECG wave amplitudes and STa amplitudes in frontal plane leads. The QRS and T wave axis shifted on the average by –17° and 41°, respectively, with considerable individual variation, which altered the diagnostic criteria.Conclusion:The ECG amplitudes and STa changes produced by the MLL system showed that all remains within the clinical limits, except the R wave amplitude in the modified lead I. It is evident that the MLL system produced deviations in frontal plane QRS axis which altered the diagnostic interpretation.

Influences of active control on elastic wave propagation in a weakly nonlinear phononic crystal with a monoatomic lattice chain

Different from the linear phononic crystals, elastic waves can exhibit more interesting phenomena in periodic structures with nonlinear properties. By the active control action, elastic wave characteristics can be tuned based on the demand in practical application. This work discusses the possibility of the active control action on elastic waves in phononic crystals with the weakly nonlinear monoatomic lattice chain. Based on the Lindstedt-Poincaré method, the approximate solution of the dispersion relation is derived. Numerical calculations are performed to discuss the influences of the active control action on wave propagation properties. In order to present the features of nonlinear elastic wave dynamics, it is mainly focused on the effects of active control accompanied by the changes of the elastic wave amplitude, nonlinear degree, hard and soft nonlinearities. It is expected to extend the analysis and design of new phononic crystal devices for both the theory and application fields.

Effects of partial sleep deprivation on slow waves during non-rapid eye movement sleep: A high density EEG investigation

ObjectiveChanges in slow waves during non-rapid eye movement (NREM) sleep in response to acute total sleep deprivation are well-established measures of sleep homeostasis. This investigation utilized high-density electroencephalography (hdEEG) to examine topographic changes in slow waves during repeated partial sleep deprivation. MethodsTwenty-four participants underwent a 6-day sleep restriction protocol. Spectral and period-amplitude analyses of sleep hdEEG data were used to examine changes in slow wave energy, count, amplitude, and slope relative to baseline. ResultsChanges in slow wave energy were dependent on the quantity of NREM sleep utilized for analysis, with widespread increases during sleep restriction and recovery when comparing data from the first portion of the sleep period, but restricted to recovery sleep if the entire sleep episode was considered. Period-amplitude analysis was less dependent on the quantity of NREM sleep utilized, and demonstrated topographic changes in the count, amplitude, and distribution of slow waves, with frontal increases in slow wave amplitude, numbers of high-amplitude waves, and amplitude/slopes of low amplitude waves resulting from partial sleep deprivation. ConclusionsTopographic changes in slow waves occur across the course of partial sleep restriction and recovery. SignificanceThese results demonstrate a homeostatic response to partial sleep loss in humans.