A conceptual model for changes in finger photoplethysmograph signals caused by hand posture and isothermic regulation

Objective. To observe changes in baseline and pulsatile light absorbance (photoplethysmograph, PPG) in the finger-tip, by raising the hand above the horizontal plane in recumbent subjects. We applied current knowledge of the circulation to the finger-tip, particularly arteriovenous anastomoses (AVAs), and the physiology of the venous circulation. Approach. We studied healthy young volunteers in a quiet thermoneutral environment. A finger plethysmograph on the non-dominant hand recorded transmission of red and infra-red light, and the values were converted into absorbance to allow comparisons within and between subjects. Breathing movements were recorded unobtrusively to assess any effect on absorbance and the pulse amplitude of the signals. All body movements were passive: the study arm was elevated in a trough to about 40° above the horizontal plane. The following conditions were studied, each for 15 minutes, using the last 10 minutes for analysis: recumbent, study arm elevated, study arm horizontal, and both legs elevated by 40°. Main results. There was a substantial time-related effect, and considerable variation between subjects. Arm elevation reduced red light absorbance and increased the range of amplitudes of the PPG waveform: only in subjects with large absorbances, did waveform amplitude increase. The other main effect was that spontaneous, thermoregulatory decreases in absorbance were associated with decreases in waveform amplitude. Significance. Finger-tip vessels distend with blood when AVAs open. The vessels pulsate more strongly if venous collapse allows the vessels to become more compliant. The postcapillary circulation is likely to be an important source of pulsation.

A Study on the Cavitation and Pressure Pulsation Characteristics in the Impeller of an LNG Submerged Pump

Based on CFD analysis technology, this paper studies the cavitation performance of an LNG submerged pump and the pressure pulsation characteristics under cavitation excitation. The variation laws of the waveform, amplitude and frequency of the pressure pulsation in the impeller of the LNG submerged pump under different flow rates and NPSHa are also analysed. By calculating the root mean square of the pressure coefficient of the low-frequency pulsation, the influence of the aggravation process of cavitation on the low-frequency pulsation in the LNG submerged pump is quantitatively analysed, and the characteristics of the pressure pulsation in the LNG submerged pump under the cavitation condition are revealed. The results show that with the increase in flow rate, the pressure pulsation in the impeller becomes stronger, periodically, and the amplitude decreases. The influence of cavitation on the pressure pulsation in the primary impeller is greater than that in the secondary impeller. When critical cavitation occurs, the low-frequency signal amplitude of pressure pulsation in the primary impeller increases and exceeds the blade frequency, becoming the main frequency.

Design of a New Seismoelectric Logging Instrument

To increase the accuracy of reservoir evaluation, a new type of seismoelectric logging instrument was designed. The designed tool comprises the invented sonde-structured array complex. The tool includes several modules, including a signal excitation module, data acquisition module, phased array transmitting module, impedance matching module and a main system control circuit, which are interconnected through high-speed tool bus to form a distributed architecture. UC/OS-II was used for the real-time system control. After constructing the experimental measurement system prototype of the seismoelectric logging detector, its performance was verified in the laboratory. The obtained results showed that the consistency between the multi-channel received waveform amplitude and benchmark spectrum was more than 97%. The binary phased linear array transmitting module of the instrument can realize 0° to 20° deflection and directional radiation. In the end, a field test was conducted to verify the tool’s performance in downhole conditions. The results of this test proved the effectiveness of the developed seismoelectric logging tool.

Abstract 11156: Thoracic Bioimpedance Ventilation Waveforms: Increased Amplitude with Larger Tidal Volume and Female Sex

Introduction: Effective ventilation during 30:2 CPR has been linked to improved outcomes, but definitive evidence is lacking. We developed a method to identify thoracic bioimpedance ventilation waveforms from defibrillator recordings. Hypothesis: Bioimpedance ventilation waveform amplitude is proportional to tidal volume. It is possible to identify a minimum amplitude for a valid ventilation waveform. Methods: To determine the relationship between tidal volume and bioimpedance waveform amplitude, we studied 26 healthy volunteers (12 males and 14 females). Volunteers breathed fixed positive pressure tidal volumes (250mL, 300 mL, 400 mL, 600 mL, and 800 mL) given by a Maquet SERVO-I ventilator (Getinge US Sales, Wayne, NJ, USA) through a mouthpiece while a Lifepak12 (Physio-Control, Redmond, WA) defibrillator recorded thoracic bioimpedance through electrode pads placed on the chest. We measured the impedance amplitudes of six breaths at each tidal volume and the weight and height of each volunteer. We set the minimum effective tidal volume at 250 mL. Results: For males and females, respectively, mean (±SD) was 180.1±8 cm vs. 164±3.5 cm, and mean weight was 85.6±9.6 kg vs. 58.3±8.6 kg. Median (IQR) bioimpedance amplitude for each tidal volume split by sex is shown in the Figure (Y-axis, 1 mm = 0.25 Ohm). Conclusion: Bioimpedance amplitude is proportional to tidal volume and also varies by height, weight, and sex. Sex may be a possible surrogate for height and weight. The minimum amplitude is 0.375 Ohm for a valid bioimpedance ventilation waveform.

Preliminary Results of Automatic P-Wave Regional Earthquake Arrival Time Picking using Machine Learning with Kurtosis and Skewness as The Input Parameters

The traditional method in determining first arrival time of earthquake dataset is time consuming process due to waveform manual inspection. Additional waveform attributes can help determine events detection. One of the widely used attribute is The Short Term Averaging/Long Term Averaging (STA/LTA) which is simply division moving average of waveform amplitude between short time and longer time. Alternatively, waveform attribute can also be built using kurtosis and skewness. The kurtosis attribute is defined as sharpness of data distribution. By definition, the maximum signal should be at or close to the P wave arrival. The skewness is typically used to show normal distribution of the data. The uniqueness of this method is that it has an ability to determine whether the first P wave arrival has positive of negative number. The skewness calculation is similar to kurtosis but it uses the power of 3 instead of 4. With the objective of generating efficient scheme to pick first time arrival, we explore use artificial neural network and a combination of kurtosis and skewness attributes. We use a collection of magnitude events with moment magnitude larger than 3 located close to Moluccas island, Indonesia. We collected all events information from the Indonesian Agency of Meteorology, Climatology and Geophysics. The process is started with manually pick all P wave arrivals using manual inspection. Next, we trained the artificial neural network with attributes numbers as inputs and arrival time we manually picked as the output. In total we used 100 regional events that has clear P wave phases. Then, we validated the results until reaching 0.99 accuracy. In the last step, we tested the once trained procedures on new waveforms contained events. Current result shows an average of 0.4s different between manual pick and trained picked from machine learning. The accuracy can be improved by applying a band pass 0.1-2 Hz filtering with an average of 0.2s.

Preliminary Results of Automatic P-Wave Regional Earthquake Arrival Time Picking Using Machine Learning with STA/LTA As the Input Parameters

The Short Term Averaging/Long Term Averaging (STA/LTA) has been widely used to detect earthquake arrival time. The method simply calculates the ratio of moving average of the waveform amplitude at short and long-time windows. However, although STA/LTA signals can distinguish between real events and noise, we still recognize some lack of accuracies in first P wave arrival pickings. In this study, we attempt to implement one machine learning method popularly, Artificial Neural Network (ANN) that employ input, hidden and output layer similar as human brain works. Note that in this study, we also try to add input parameters with another derivative signal attributes such as Recursive STA/LTA and Carl STA/LTA. The processing step started by collecting event waveforms from the Agency of Meteorology, Climatology and Geophysics. We chose regional events with moment magnitude higher than 3 in the Maluku region Indonesia. Next, we apply all STA/LTA attributes to the input waveforms. We also tested our STA/LTA with synthetic data and additional noise. Further step, we manually picked the arrival of P wave events and used this as the output for ANN. In total, we used 100 events for arrival data training in P wave phases. In the validation process, an accuracy of more than 0.98 can be obtained after 200 iterations. Final outputs showed, that in average, the difference between manual picking and automatic picking from ANN is 0.45 s. We are able to increase the accuracy by band pass filter (0.1 – 3 Hz) all signal and improve the mean into 0.15s difference between manual picking and ANN picks.

Feature Selection and Mislabeled Waveform Correction for Water–Land Discrimination Using Airborne Infrared Laser

The discrimination of water–land waveforms is a critical step in the processing of airborne topobathy LiDAR data. Waveform features, such as the amplitudes of the infrared (IR) laser waveforms of airborne LiDAR, have been used in identifying water–land interfaces in coastal waters through waveform clustering. However, water–land discrimination using other IR waveform features, such as full width at half maximum, area, width, and combinations of different features, has not been evaluated and compared with other methods. Furthermore, false alarms often occur when water–land discrimination in coastal areas is conducted using IR laser waveforms because of environmental factors. This study provides an optimal feature for water–land discrimination using an IR laser by comparing the performance of different waveform features and proposes a dual-clustering method integrating K-means and density-based spatial clustering applications with noise algorithms to improve the accuracy of water–land discrimination through the clustering of waveform features and positions of IR laser spot centers. The proposed method is used for practical measurement with Optech Coastal Zone Mapping and Imaging LiDAR. Results show that waveform amplitude is the optimal feature for water–land discrimination using IR laser waveforms among the researched features. The proposed dual-clustering method can correct mislabeled water or land waveforms and reduce the number of mislabeled waveforms by 48% with respect to the number obtained through traditional K-means clustering. Water–land discrimination using IR waveform amplitude and the proposed dual-clustering method can reach an overall accuracy of 99.730%. The amplitudes of IR laser waveform and the proposed dual-clustering method are recommended for water–land discrimination in coastal and inland waters because of the high accuracy, resolution, and automation of the methods.

Waveform Amplitude and Temporal Symmetric/Asymmetric Characteristics of Phoneme and Syllable Segments in the W-1 Spondaic Words Recorded by Four Speakers

Background The amplitude and temporal asymmetry of the speech waveform are mostly associated with voiced speech utterances and are obvious in recent graphic depictions in the literature. The asymmetries are attributed to the presence and interactions of the major formants characteristic of voicing with possible contributions from the unidirectional air flow that accompanies speaking. Purpose This study investigated the amplitude symmetry/asymmetry characteristics (polarity) of speech waveforms that to our knowledge have not been quantified. Study Sample Thirty-six spondaic words spoken by two male speakers and two female speakers were selected because they were multisyllabic words providing a reasonable sampling of speech sounds and four recordings were available that were not related to the topic under study. Research Design Collectively, the words were segmented into phonemes (vowels [130], diphthongs [77], voiced consonants [258], voiceless consonants [219]), syllables (82), and blends (6). For each segment the following were analyzed separately for the positive and negative datum points: peak amplitude, the percent of the total segment datum points, the root-mean-square (rms) amplitude, and the crest factor. Data Collection and Analyses The digitized words (44,100 samples/s; 16-bit) were parsed into 144 files (36 words × 4 speakers), edited, transcribed to numeric values (±1), and stored in a spread sheet in which all analyses were performed with in-house routines. Overall approximately 85% of each waveform was analyzed, which excluded portions of silent intervals, transitions, and diminished waveform endings. Results The vowel, diphthong, and syllable segments had durations (180–220 ms) that were about twice as long as the consonant durations (∼90 ms) and peak and rms amplitudes that were 6 to 12 dB higher than the consonant peak and rms amplitudes. Vowel, diphthong, and syllable segments had 10% more positive datum points (55%) than negative points (45%), which suggested temporal asymmetries within the segments. With voiced consonants, the distribution of positive and negative datum points dropped to 52 and 48% and essentially was equal with the voiceless consonants (50.3 and 49.6%). The mean rms amplitudes of the negative datum points were higher than the rms amplitudes for the positive points by 2 dB (vowels, diphthongs, and syllables), 1 dB (voiced consonants), and 0.1 dB (voiceless consonants). The 144 waveforms and segmentations are illustrated in the Supplementary Material along with the tabularized positive and negative segment characteristics. Conclusions The temporal and amplitude waveform asymmetries were by far most notable in segments that had a voicing component, which included the voiced consonants. These asymmetries were characterized by larger envelopes and more energy in the negative side of the waveform segment than in the positive side. Interestingly, these segments had more positive datum points than negative points, which indicated temporal asymmetry. All aspects of the voiceless consonants were equally divided between the positive and negative domains. There were female/male differences but with these limited samples such differences should not be generalized beyond the speakers in this study. The influence of the temporal and amplitude asymmetries on monaural word-recognition performance is thought to be negligible.

Effects of Supplementation With Iron Syrup or Iron-Containing Multiple Micronutrient Powders on Neural Indices of Cognitive Functioning in Bangladeshi Children

Objectives Micronutrients, especially iron, play a critical role in the developing infant brain. Yet, the causal effects of iron supplementation on neurocognitive functioning in a low-income anemic population of children have not been examined. This study sought to evaluate the effects of supplementation with iron syrup and iron-containing multiple micronutrient powders (MNPs) in Bangladeshi children on habituation to familiar sounds, a marker for healthy memory development, using auditory event-related brain potentials (ERPs). Methods This study was nested within the Benefits and Risks of Iron Supplementation in Children (BRISC) trial, a double blinded double dummy randomized controlled trial (RCT). At 8 months of age, 3300 children were randomized to receive 3 months of 1) iron syrup + placebo MNPs, or 2) MNPs (containing iron, retinol, zinc, and Vitamin C) + placebo iron syrup, or 3) placebo iron syrup and placebo MNPs. ERPs in response to an auditory roving oddball paradigm were measured in a random subset of 441 children at 3 months post-intervention (11 months of age) and 595 children after a further 9 months follow-up (20 months of age). ERP measures indexing aspects of habituation included the [deviant minus standard] difference waveform amplitude, N2 waveform amplitude, and the difference in deviant-evoked ERP amplitudes between the first and second half of the paradigm. Intention-to-treat analyses on ERP outcomes using linear models were used at 11 and 20 months of age separately. Results Baseline characteristics were balanced between treatment groups. Overall prevalence of anemia was 43.7% and iron deficiency was 28.4%. Intention-to-treat analyses indicated no significant treatment effects of iron or MNPs on the difference waveform amplitude at 11 months of age [mean difference (MD, 95% CI) iron vs placebo 0.24 (–1.03, 1.51); MNP vs placebo 0.59 (–0.70, 1.88)] and 20 months of age [(MD, 95% CI) iron vs placebo 0.50 (–0.62, 1.63); MNP vs placebo 0.24 (–0.89, 1.38)]. There were no differences by treatment arm for the other ERP measures. Conclusions Results from a rigorous prospectively powered sub-study of an RCT in an iron deficient population indicated no significant effects of supplementation with iron or MNPs on neural indices of habituation. Funding Sources NHMRC and The University of Melbourne.

Diseño de un sistema inalámbrico de estimulación eléctrica funcional adaptativo

In recent years, Functional Electrical Stimulation (FES) became a promising rehabilitation treatment for Spinal Cord Injuries (SCI). Different topologies for FES systems have been implemented to rehabilitate specific muscles, but this limits their adaptability for the stimulation of any other one. On the other hand, many of these designs are limited in portability because they do not use wireless technology. In this paper, we propose the design of an FES system that generates monophasic and biphasic current pulses in an amplitude range of 0 to 26 mA. In addition, the output stage of the FES system we propose, includes the use of a differential current source, whose amplitude can be manipulated by means of two digital potentiometers. Waveform, amplitude, frequency and pulse width can be manipulated directly from the Graphical User Interface (GUI) of the FES system. Moreover, a wireless interface was implemented between the computer and the system to give greater portability to the user and more movility to the patient. All these features make our design adaptable for different rehabilitation treatments.