Mean Peak Frequency Research Articles

Stress-Induced Ultrasonic Vocalization in Laboratory Rats and Mice: A Scoping Review

Introduction: Ultrasonic vocalization (USV) can indicate affective states—including psychosocial stress—in mice and rats. However, stress-induced USV changes could be confounded by laboratory experimental variables such as the type of behavioral stress paradigm, the elicitation method, rodent strain, etc. We sought to provide a review of the current literature to delineate how psychosocial stress-altered rodent USVs may be affected by factors of age, sex, strain, species, elicitation paradigm, and stressor. Methods: We used PubMed, Scopus (Elsevier), PsycINFO (EBSCO), and the following Web of Science (Clarivate) databases: Biological Abstracts, CAB Abstracts, Science Citation Index-Expanded, and Emerging Sources Citation Index. The studies identified by our search strategy were independently screened by two authors with the following inclusion criteria: peer-reviewed, in English, reported original data, and described USV in response to stress in rats or mice. The data extracted included USV acoustic parameters (mean peak frequency and mean amplitude (loudness)), details of the stress and USV elicitation paradigms, rodent species, age, and sex variables. Results: The following screening of 5309 titles/abstracts and 687 full-text articles revealed 148 articles. Footshock (20%), cold exposure (14%), and maternal separation (23.5%) were the most commonly used stress paradigms (duration and type of stressor varied across studies), with the total number of USV calls being the most commonly reported acoustic outcome. In rats, 121 articles described stress-altered USVs, while 25 studies reported the same in mice, and two reported multiple rodent species (rats and mice, alongside other rodent species such as gerbils). With respect to stress-altered USV changes with age, mice and rats increase USV rates after birth, with a peak around 6 to 10 days, and decrease USVs until weanling age. Of the five studies that reported sex-related differences in stress-induced USVs, females had an increased number of calls and lower average peak frequency in response to stress when compared to males. Only two to four studies reported strain-related differences in stress-induced vocalizations in rats and mice, respectively. Conclusions: The data from this review lay the groundwork for better understanding rodent USVs in response to psychosocial stress with effects of elicitation paradigm, stressor, age, and sex.

Novel approach of slow pathway ablation in common atrioventricular nodal reentrant tachycardia by peak frequency map

Abstract Background It is difficult to visualize slow pathway in atrioventricular nodal reentrant tachycardia (AVNRT) even with recent high-density mapping. This could be because the slow pathway potential is buried by the potential of atrial working cells during sinus rhythm and tachycardia. In other words, it is extremely difficult for conventional 3D mapping systems to annotate slow pathway potential even though the histological run of slow pathway is known .[1], [2] Purpose The purpose of this study is to visualize the atrial myocardial junction of rightward inferior extension by the peak frequency map of Ensite X in common AVNRT and to evaluate whether relative high frequency (HF) sites in low voltage area extending from Koch's triangle to tricuspid annulus (TA) is effective targets of slow pathway ablation and the characteristics of junctional rhythm (JR) after radiofrequency application. Methods This study is single-center prospective cohort study. In 37 consecutive common AVNRT patients, novel approach and conventional approach of slow pathway ablation were performed in 17 and 20 patients, respectively. The conventional approach is anatomical and electrophysiological approach. Peak frequency map was performed during sinus rhythm with HD-grid catheter in novel approach patients. A frequency scanning is performed to locate relative HF sites on the tricuspid annulus. Radiofrequencey application is 30 W, 30-60 sec, and the end point was no inducibility or until one echo under load of isoproterenol. Results The success rate was 100 % with two approaches. The relative HF sites in low voltage area were distributed at the TA side from 4 to 5 o'clock in all novel approach patients, mean peak frequency in success site was 419 ± 87 Hz. The distance to His bundle from success site was farther (24.8 ± 4.9 vs. 12.8 ± 4.4 mm, p<0.001), JR was slower (93 ± 14 vs. 118 ± 10 bpm, p=0.013), time to JR occurrence was shorter (3.0 ± 1.3 vs. 7.6 ± 4.6 sec, p=0.003), and elimination rate of jump up (78 % vs. 40 %, p=0.06) was higher in novel approach. Conclusions The relative HF sites in low voltage area at TA side from 4 to 5 o'clock by peak frequency map could be novel target of slow pathway ablation with high success rate and sufficient safety and efficiency.peak frequency map

Deep learning for retrieving omni-directional ocean wave spectra from spaceborne synthetic aperture radar

Synthetic Aperture Radar (SAR) is a unique remote sensing instrument imaging ocean surface waves in two dimensions with high spatial resolution regardless of sunlight and weather conditions. However, due to the nonlinear imaging process, the ocean wave spectra cannot be retrieved directly from SAR data. The emergence of deep learning (DL) techniques provides a new paradigm for addressing this challenge. In this paper, a deep-learning-based model, called Wave-Spec-CNN, is proposed for retrieving omni-directional ocean wave spectra from SAR data. This model is constructed using approximately 21,000 collocations of Sentinel-1 Interferometric Wide swath mode images matched with global in-situ buoy data. The model adapts the convolution neural network (CNN) to accommodate the multi-valued nature of omni-directional ocean wave spectra, enhances performance by integrating a calibration branch and further incorporates physical characteristics into the training process. The results demonstrate consistency with buoy measurements for significant wave height (SWH) in the range of 0.5 m to 6 m, yielding a root-mean-square error (RMSE) of 0.51 m on the validation dataset, comparable to traditional physical-based methods. In terms of mean wave period (MWP) and peak frequency (PF), the achieved RMSEs are of 1.24 s and 0.03 Hz, respectively. The retrieved omni-directional ocean wave spectra also allow to separate swell and windsea components for respective comparisons with those derived by in-situ buoy data. The RMSEs of respective SWH comparisons are of 0.46 m and 0.42 m. This research represents an initial endeavor into utilizing DL for the long-standing challenge of SAR inversion for ocean wave spectra, as well as providing valuable insights for employing DL in multi-parameter inversion tasks in remote sensing.

Peak frequency mapping usefulness and utilization for typical AVNRT ablation

Abstract Background Accurate identification of slow pathway for the AVNRT ablation is important to achieve successful result and avoid complications mainly AV nodal block. There were some developments to produce precise image to locate this such as identify low voltage bridge (LVB) using electro-anatomical mapping and visualization of direct slow pathway capture (DCSP). The peak frequency (PF) associated with bipolar EGMs is a novel parameter which may serve to distinguish near filed (NF) from far field (FF) electrocardiogram (EGM) components. This technique can be used to differentiate sub-components derived from high density mapping. Previous study suggested this mapping appears to assist in substrate differentiation, pathway localization, and contact assessment. However, this approach has been never evaluated clinically in AVNRT ablation Objective This study conducted to evaluate the usefulness and utilization of the peak frequency mapping to identify the slow pathway location. Method The study conducted in November to December 2023 where twenty consecutive patients with common AVNRT were included in the study. Regular bipolar voltage and activation maps were generated with a regular 4 mm tip catheter. Following this, peak frequency maps (PF) were computed online prior ablation and displayed on the activation map with shadowed areas where PF was <200 Hz (figure, left panel). Focal radiofrequency application (RFa) was directed to the areas of late activation (figure, left panel) and low frequency (figure, right panel) (LA-LF). Successful ablation reached if junctional rhythm was recorded during RFa and AVNRT was no longer inducible afterwards. Results Twenty patients (48 ±15 years, 75% female) were enrolled in the study. A late activation low frequency area of 0.92±0.48 cm2 was found in 18 of them. This study revealed that there was a difference between PF in the slow pathway area compared to the adjacent area where the mean PF at the slow pathway area was 175.5 ± 37.1 Hz (analysis per patient) and 170.1 ± 48.10 Hz (analysis per recording site) which was lower and differed significantly than the PF recorded at the adjacent atrial area (279.71 ± 28.11 Hz per patient, 279.91 ± 69.47 Hz per recording site) (P<0.0001). Following the mapping, RFa were successfully applied at these late activation low-frequency (LA-LF) area induced junctional rhythm in 17 patients. AVNRT was no longer inducible after the ablation in all 17 patients. Additional RFa were often given to reinforce the result (11 ± 9 RFa, 4.03 ± 3.35 min RFa time). Conclusion The peak frequency mapping could be performed to map the slow nodal pathway which is often located in an area of late activation and low frequency.

Localization of critical isthmus in left atrial macroreentrant tachycardias: insights from peak frequency mapping during sinus rhythm and coronary sinus pacing

Abstract Background Successful ablation of left atrium macroreentrant tachycardia (LAMRT) has advanced significantly, benefiting from an enhanced understanding of reentrant mechanisms and technological innovations. However, challenges like difficult inductions and the presence of multiple coexistent LAMRTs can complicate tachycardia mapping, potentially resulting in recurrences during follow-up. Consequently, there is a growing need for strategies that focus on pinpointing the critical isthmus of conduction (CIC) in LAMRT circuits outside of tachycardia episodes. Peak frequency (PF) mapping, with its ability to discern near-field (NF) from far-field (FF) electrograms (EGMs) in low voltage areas, emerges as a valuable tool for precisely identifying these critical isthmuses. Purpose This study aims to investigate whether the accurate identification of the CIC in LAMRT circuits is achievable through PF mapping during sinus rhythm or coronary sinus pacing. Methods Patients with sustained LAMRT undergoing radiofrequency (RF) ablation were enrolled. Utilizing a 16-pole grid catheter (HD-Grid), bipolar voltage and activation maps were generated during LAMRT. PF maps were retrospectively computed. Voltage, activation, and PF maps were also created during sinus rhythm and coronary sinus pacing (500 ms). Potential CICs (P-CICs) were defined as areas with low voltage (<0.2 mV) and high PF (>250 Hz), covering a surface area of <2 cm2 by adjusting the PF threshold above 250 Hz. Only instances of LAMRT terminated by focal RF lesions (boundary <1.5 cm diameter) were included. Confirmed CICs (C-CICs) were identified at sites where LAMRT termination occurred due to RF application. The localization of P-CICs found during LAMRT, sinus rhythm (SR), and coronary sinus pacing (CSP) mapping, in relation to that of CIC, was analyzed, considering them matching if separated by <10 mm. Results Twenty-four consecutive patients with 26 atrial tachycardias (ATs) were prospectively enrolled, including 18 LAMRTs (270±63 ms) terminated by 2.2±2.9 focal RF lesions after 9.4±8.2 sec of energy delivery. A P-CIC was consistently identified at the tachycardia termination site during LAMRT mapping, with a visual cutoffs discrimination score (1-5) of 4.1±0.7, a mean P-P voltage cutoff <0.22±0.09 mV, and a mean PF cutoff >330±67 Hz in all patients. Importantly, P-CICs found during SR and CSP mapping matched those found during LAMRT mapping in all patients (figure). Conclusion PF mapping demonstrates precision in identifying the critical isthmus in LAMRT circuits during actual tachycardia episodes. Notably, the consistent identification of the CIC through PF mapping during sinus rhythm or coronary sinus pacing exhibits a high correlation with findings during LAMRT mapping. This approach holds promising potential for reducing arrhythmia recurrences, especially in scenarios involving multiple or unmappable LAMRTs.

Characterization of sound production by the pot-bellied seahorse (Hippocampus abdominalis) during feeding.

Sound production during feeding by the pot-bellied seahorse, Hippocampus abdominalis, was quantified with an observation of clicks (acoustic signal) and snicks (visual behavior). Female, male, and juvenile seahorses had feeding sounds characterized for peak (dominant) frequency (Hz), sound pressure level (SPL), and duration (ms). Subject body size and condition was estimated by standard length (SL, cm), to determine an estimate of body condition index (BCI). An inverse correlation between mean peak frequency (Hz) of clicks and SL was found for females. A negative correlation between peak frequency (Hz) of clicks and a residual BCI was determined for both males and females, suggesting that acoustic signals may contain information regarding fitness.

Investigation on the contribution of swim bladder to hearing in crucian carp (Carassius carassius).

The swim bladder in some teleost fish functions to transfer the sound energy of acoustic stimuli to the inner ears. This study uses the auditory evoked potential tests, micro-computed tomography scanning, reconstruction, and numerical modeling to assess the contribution of the swim bladder to hearing in crucian carp (Carassius carassius). The auditory evoked potential results show that, at the tested frequency range, the audiogram of fish with an intact swim bladder linearly increases, ranging from 100 to 600 Hz. Over this frequency, the sound pressure thresholds have a local lowest value at 800 Hz. The mean auditory threshold of fish with an intact swim bladder is lower than that of fish with a deflated swim bladder by 0.8-20.7 dB. Furthermore, numerical simulations show that the received pressure of the intact swim bladders occurs at a mean peak frequency of 826 ± 13.6 Hz, and no peak response is found in the deflated swim bladders. The increased sensitivity of reception in sound pressure and acceleration are 34.4 dB re 1 μPa and 40.3 dB re 1 m·s-2 at the natural frequency of swim bladder, respectively. Both electrophysiological measurement and numerical simulation results show that the swim bladder can potentially extend hearing bandwidth and further enhance auditory sensitivity in C. carassius.

Peak frequency mapping of atypical atrial flutter.

Peak frequency (PF) mapping is a novel method that may identify critical portions of myocardial substrate supporting reentry. The aim of this study was to describe and evaluate PFmapping combined with omnipolar voltage mapping in the identification of critical isthmuses of left atrial (LA) atypical flutters. LA omnipolar voltage and PF maps were generated in flutter using the Advisor HD-Grid catheter (Abbott) and EnSite Precision Mapping System (Abbott) in 12 patients. Normal voltage was defined as ≥0.5 mV, low-voltage as 0.1-0.5 mV, and scar as <0.1 mV. PF distributions were compared with ANOVA and post hoc Tukey analyses. The 1 cm radius from arrhythmia termination was compared to global myocardium with unpaired t-testing. The mean age was 65.8 ± 9.7 years and 50% of patients were female. Overall, 34 312 points were analyzed. Atypical flutters most frequently involved the mitral isthmus (58%) or anterior wall (25%). Mean PF varied significantly by myocardial voltage: normal (335.5 ± 115.0 Hz), low (274.6 ± 144.0 Hz), and scar (71.6 ± 140.5 Hz) (p < .0001 for all pairwise comparisons). All termination sites resided in low-voltage regions containing intermediate or high PF. Overall, mean voltage in the 1 cm radius from termination was significantly lower than the remaining myocardium (0.58vs. 0.95 mV, p < .0001) and PF was significantly higher (326.4vs. 245.1 Hz, p < .0001). Low-voltage, high-PF areas may be critical targets during catheter ablation of atypical atrial flutter.

Pulsed Vibro-Acoustic Analysis Technique for Monitoring Bone Health in Preterm Infants: A Pilot Study.

Despite advances in neonatal care, metabolic bone disease of prematurity (MBDP) remains a common problem in preterm infants. The development of non-invasive and affordable diagnostic approaches can be highly beneficial in the diagnosis and management of preterm infants at risk of MBDP. In this study, we present an ultrasound method called pulsed vibro-acoustic analysis to investigate the progression of bone mineralization in infants over time versus weight and postmenstrual age. The proposed pulsed vibro-acoustic analysis method is used to evaluate the vibrational characteristics of the bone. This method uses the acoustic radiation force of ultrasound to vibrate the bone. The generated acoustic waves are detected using a hydrophone placed on the skin over the tibia. The frequency of vibration and the speeds of received acoustic waves have information regarding the material property of the bone. We examined the feasibility of this method through an in vivo study consisting of 25 preterm and 10 full term infants. The pulsed vibro-acoustic data were acquired longitudinally in preterm infants with multiple visits and at a single visit in full term infants. Speed of sound and mean peak frequency of slow and fast sound waves recorded by hydrophone were used to analyze bone mineralization progress. Linear mixed model was used for statistical analysis in characterizing the mineralization progress in preterm infants compared to data from full term subjects. Significance changes in wave parameters (speed of sound and mean peak frequency) with respect to the postmenstrual age and weight in preterm infants were observed with p-values less than 0.05. Statistical significances in speed of sound measurement for both fast and slow waves were observed between preterm and full term infants, with p-values of <0.01 and 0.02, respectively. The results of this pilot study indicate the potential use of vibro-acoustic analysis for monitoring the progression of bone mineralization in preterm infants.

Directional and amplitude characteristics of pulsed call sequences in captive free-swimming Pacific white-sided dolphins (Lagenorhynchus obliquidens).

We investigated the directional properties and gain control of a pulsed call sequence that functions as a contact call in Pacific white-sided dolphins (Lagenorhynchus obliquidens). The pulsed call sequences were stereotyped patterns composed of three or more pulsed call elements and were collected from two dolphins, separated into adjacent pools, and allowed to swim freely. Eight hydrophones and an overhead camera were used to determine the positions and directions of the participants. The mean peak frequency and source levels were 8.4 ± 4.4 (standard deviation)-18.7 ± 12.7 kHz and 160.8 ± 3.8 to 176.4 ± 7.9 dB re 1 μPa (peak-to-peak), respectively, depending on the element types. The elements were omnidirectional, with mean directivity index of 0.9 ± 3.4 dB. The dolphins produced sequences, regardless of their relative position and direction to the lattice, leading to the adjacent pool where the conspecific was housed. They increased the amplitude by 6.5 ± 4.6 dB as the distance from the caller to an arbitrary point in the adjacent pool doubled. These results suggest that callers broadcast pulsed call sequences in a wide direction to reach dispersed conspecifics. However, they can adjust the acoustic active space by controlling the source levels.

Flexible, high-resolution cortical arrays with large coverage capture microscale high-frequency oscillations in patients with epilepsy.

Effective surgical treatment of drug-resistant epilepsy depends on accurate localization of the epileptogenic zone (EZ). High-frequency oscillations (HFOs) are potential biomarkers of the EZ. Previous research has shown that HFOs often occur within submillimeter areas of brain tissue and that the coarse spatial sampling of clinical intracranial electrode arrays may limit the accurate capture of HFO activity. In this study, we sought to characterize microscale HFO activity captured on thin, flexible microelectrocorticographic (μECoG) arrays, which provide high spatial resolution over large cortical surface areas. We used novel liquid crystal polymer thin-film μECoG arrays (.76-1.72-mm intercontact spacing) to capture HFOs in eight intraoperative recordings from seven patients with epilepsy. We identified ripple (80-250 Hz) and fast ripple (250-600 Hz) HFOs using a common energy thresholding detection algorithm along with two stages of artifact rejection. We visualized microscale subregions of HFO activity using spatial maps of HFO rate, signal-to-noise ratio, and mean peak frequency. We quantified the spatial extent of HFO events by measuring covariance between detected HFOs and surrounding activity. We also compared HFO detection rates on microcontacts to simulated macrocontacts by spatially averaging data. We found visually delineable subregions of elevated HFO activity within each μECoG recording. Forty-seven percent of HFOs occurred on single 200-μm-diameter recording contacts, with minimal high-frequency activity on surrounding contacts. Other HFO events occurred across multiple contacts simultaneously, with covarying activity most often limited to a .95-mm radius. Through spatial averaging, we estimated that macrocontacts with 2-3-mm diameter would only capture 44% of the HFOs detected in our μECoG recordings. These results demonstrate that thin-film microcontact surface arrays with both highresolution and large coverage accurately capture microscale HFO activity and may improve the utility of HFOs to localize the EZ for treatment of drug-resistant epilepsy.

PO-05-040 APPLICATION OF ELECTROGRAM PEAK FREQUENCY VALUE FOR IDENTIFICATION OF SCAR-RELATED VENTRICULAR TACHYCARDIA ISTHMUS DURING SINUS RHYTHM

Isolated late activation mappings (ILAMs) can identify possible ventricular tachycardia (VT) isthmus during sinus rhythm (SR). The interference of far-field potentials at the deceleration zone (DZ) may cause misleading results. Electrogram peak frequency (PF) has the potential to discriminate between far-field and near-field signals. We aimed to identify the VT isthmus by applying PF over SR substrate maps. Ten patients with scar-related VT (ischemic/nonischemic cardiomyopathy 6/4) were studied. VT isthmuses were identified based on the activation maps, entrainment, and ablation results during tachycardia. The accuracy of PF maps in detecting potential VT isthmuses during SR before ablation was assessed. Twelve VT isthmuses were identified. The bipolar mean voltage and PF of isthmus areas over the pre-ablation SR map were 0.25 ± 0.12 mV and 307.5 ± 54.3 Hz, respectively. All isthmuses were within low voltage zones (LVZ) with PF of more than 250Hz. Before ablation, 11 of 25 (44.0%) DZs identified from ILAM by annotating the last deflection EGMs in LVZ were compatible with VT isthmuses (mean PF 311.0 ± 66.0Hz); mean PF of DZs which were not isthmus locations was 177.6 ± 51.5 Hz. There were 12 of 15 (80.0%) DZs on ILAMs constructed by annotating PF EGMs compatible with VT isthmuses. VT isthmus is mostly located in LVZ (<0.5 mV) with PF value over 250Hz from pre-ablation SR maps. The DZs during SR with a low PF could be bystanders. Identifying DZs by annotating EGMs with PF, rather than last deflections, is better to discriminate critical VT substrates.

PO-05-092 BIPOLAR ELECTROGRAM PEAK FREQUENCY VALUE DERIVED FROM HIGH-DENSITY ELECTROANATOMIC MAPPING EFFICIENTLY IDENTIFIES THE CRITICAL ISTHMUS IN SCAR-RELATED VENTRICULAR TACHYCARDIA

It is of challenges to differentiate local activities from far-field potentials, especially the multicomponent electrograms of diastolic potentials in scar-related reentrant ventricular tachycardia (VT). The peak frequency (PF) of each electrogram has the potential to discriminate near-field from far-field potentials. The study aimed to identify the VT isthmus by applying PF criteria on VT activation maps. The study consisted of 10 patients with scar-related VT (ischemic/nonischemic cardiomyopathy 6/4). The characteristics of the VT circuits were assessed using high-density multielectrode catheters. VT isthmuses were identified based on activation maps, entrainment, and ablation results. The accuracy of applying PF value over the activation map in detecting VT isthmus was assessed. 12 VT isthmuses were identified. The mean bipolar voltage and PF of the VT isthmuses were 0.26 ± 0.13 mV and 319.3 ± 58.6 Hz respectively. All isthmuses were within areas of bipolar voltage less than 0.5 mV and PF of more than 250 Hz. With the automated -dv/dtmax annotation during VT, the isthmus could be identified in 5 of 12 (41.7%) VT circuits without manual annotation. By automated PF annotation, the VT isthmus could be identified in 9 of 12 (75.0%) VT circuits without the need for manual adjustment. VT isthmus was always located in the electrogram with bipolar LVZ (<0.5 mV) with a PF value over 250Hz during VT. Moreover, the VT isthmus could be more intuitively identified by the automated peak frequency annotation than -dv/dtmax annotation in the current daily practice using high-density 3D electroanatomic mapping system.

PO-03-119 ATRIAL SUBSTRATE CAN BE ASSESSED DURING PACING INSTEAD OF SINUS RHYTHM? – ADVANTAGE AND LIMITATION OF SINUS-NODE PACING MAP-

Atrial pacing (AP) is frequently used instead of sinus rhythm (SR) during substrate mapping to save time with stable pacing rhythm. However, the effect of pacing on atrial substrates such as activation, voltages and frequency of electrograms has not been systematically examined. We aimed to elucidate the advantage and limitation of AP-map. In patients who underwent catheter ablation for atrial fibrillation, atrial substrate maps of left atrium were created after the ablation during SR, AP with the cycle length of 300ms (AP300) and AP with the cycle length of 600ms (AP600) with a HD grid catheter using the Ensite X mapping system. AP was performed from high right atrium around sinus node with a spot catheter. Mapping time, the number of acquired electrograms points, mean omnipolar voltage of electrograms, and mean peak frequency of electrograms were compared among created maps. The pattern of activation in left atrium was also analyzed in each map. A total of 60 left atrium maps were created in 20 patients. The summary of the results is shown in the figure. The figure also exhibits voltage maps and peak frequency maps during SR, AP600, and AP300 of a representative case. When compared with during SR, mapping time was significantly reduced and mean voltage and mean peak frequency of electrograms significantly decreased during AP600. Moreover, mapping time was much shorter and mean peak-frequency of electrograms was much lower during AP300. The number of acquired electrogram points was significantly higher during AP300 compared with SR. Mean voltage of electrograms became significantly lower during AP300 compared with SR. Left atrial activation pattern during SR and that during AP were almost the same (Each wave front collided around the 4 o’clock or 5 o’clock of mitral annulus in all maps). Although AP-map allowed us to acquire higher-resolution maps in shorter time without changing activation pattern, amplitude and frequency of electrograms may be reduced as the cycle length of AP becomes shorter.

Echolocation clicks of free-ranging Indo-Pacific finless porpoises (Neophocaena phocaenoides) in Hainan waters.

The echolocation clicks of free-ranging Indo-Pacific finless porpoises (IPFPs, Neophocaena phocaenoides) have been rarely studied in the wild. This paper aims at describing the echolocation-click characteristics of IPFPs and examining whether IPFPs adapt their sonar system to the habitats in Hainan waters, China. The echolocation clicks were recorded using a 13 elements star-shaped array of hydrophones. A total of 65 on-axis clicks were identified and analyzed. IPFPs use echolocation clicks with a source level (SL) of 158 ± 9 dB re: 1 μPa peak-peak, mean peak, and centroid frequency of 134 ± 3 kHz, -3 dB bandwidth of 14 ± 2 kHz and produce at inter-click intervals of 104 ± 51 ms. The results relative to other porpoises show that finless porpoises in Hainan waters produce clicks with moderate SLs and high peak frequency. These results could be useful in detecting the presence and estimating the density of IPFPs during passive acoustic monitoring in the study area and serve to shed light on the interpopulation variation of click characteristics of finless porpoises as well.

Initial results on the variation of whistle characteristics of bottlenose dolphins from two neighbouring regions of the Mediterranean Sea: Northern Ionian and Southern Adriatic Sea

Bottlenose dolphins have a complex vocal repertoire that varies depending on behavioral context, social structure, group composition, and anthropogenic pressures. This current study describes the whistle characteristics of bottlenose dolphins for the first time in the South Adriatic Sea while assessing the potential differences between whistle characteristics of geographically separated dolphins within neighbouring waters of the North Ionian Sea. The results show that whistle characteristics were similar between Taranto Gulf (Italy) and Boka Bay (Montenegro), despite their spatial differences. The mean peak frequency was 10kHz for each study location while the mean minimum and maximum frequency ranged from 7 to 14kHz. The average duration of whistles was 500 milliseconds. These results share similarities with previous literature, although several studies reported slightly different mean peak frequencies, ranging up to 15kHz in the neighbouring waters of Croatia and Italy. Further, harmonics were produced and formed in 40% of the whistles in Taranto Gulf and 30% of the whistles in Boka Bay. A high incidence of harmonics has previously been associated with behavioral states (i.e., travelling) and with certain types of marine traffic (i.e., fishing vessels). Therefore, it is important to collect simultaneous data on the visual behavior of the focal group as well as document the type and density of marine traffic within the proximity of the dolphins to have an in-depth understanding of vocal behavior. Despite the similarities of whistle characteristics of Taranto and Boka Bay, the whistle contours showed notable variations. Upsweep whistles were the most regularly produced whistle type in each location, which coincides with previous studies in the Mediterranean Sea. However, the least produced whistle had a concave contour in Taranto and was flat in Boka Bay. Previous studies have confirmed that flat whistles account for the least produced whistle contour in the Mediterranean Basin. Examining the whistle characteristics and the variation in whistle contours provides an in-depth understanding of the behavioral complexity as well as its plasticity in the presence of pressure. Therefore, future studies need to include behavior, group composition, noise levels, and human presence to enable an effective understanding of variation in whistle characteristics of bottlenose dolphins.

A data-driven predictive maintenance model to estimate RUL in a multi-rotor UAS

Unmanned Aircraft Systems (UAS) has become widespread over the last decade in various commercial or personal applications such as entertainment, transportation, search and rescue. However, this emerging growth has led to new challenges mainly associated with unintentional incidents or accidents that can cause serious damage to civilians or disrupt manned aerial activities. Machine failure makes up almost 50% of the cause of accidents, with almost 40% of the failures caused in the propulsion systems. To prevent accidents related to mechanical failure, it is important to accurately estimate the Remaining Useful Life (RUL) of a UAS. This paper proposes a new method to estimate RUL using vibration data collected from a multi-rotor UAS. A novel feature called mean peak frequency, which is the average of peak frequencies obtained at each time instance, is proposed to assess degradation. The Long Short-Term Memory (LSTM) is employed to forecast the subsequent 5 mean peak frequency values using the last 7 computed values as input. If one of the estimated values exceeds the predefined 50 Hz threshold, the time from the estimation until the threshold is exceeded is calculated as the RUL. The estimated mean peak frequency values are compared with the actual values to analyze the success of the estimation. For the 1st, 2nd, and 3rd replications, RUL results are 4 s, 10 s, and 10 s, and root mean square error (RMSE) values are 3.7142 Hz, 1.4831 Hz, and 1.3455 Hz, respectively.

Assessing uterine electrophysiology prior to elective term induction of labor

ObjectiveThe purpose of this study was to determine if uterine electrophysiological signals gathered from 151 non-invasive biomagnetic sensors spread over the abdomen were associated with successful induction of labor (IOL). Study designUterine magnetomyogram (MMG) signals were collected using the SARA (SQUID Array for Reproductive Assessment) device from 33 subjects between 37 and 42 weeks gestational age. The signals were post-processed, uterine contractile related MMG bursts were detected, and parameters in the time and frequency domain were extracted. The modified Bishop score calculated at admission was used to determine the method of IOL. Wilcoxon's rank-sum test was used to compare IOL successes and failures for differences in gestational age (GA), parity, modified Bishop's score, maximum oxytocin, and electrophysiological parameters extracted from MMG. ResultsThe average parity was three times (3x) higher (1.53 versus 0.50; p = 0.039), and the average modified Bishop score was 2x higher (3.32 versus 1.63; p = 0.032) amongst IOL successes than failures, while the average GA and maximum oxytocin showed a small difference. For the MMG parameters, successful IOLs had, on average, 3.5x greater mean power during bursts (0.246 versus 0.070; p = 0.034) and approximately 1.2x greater mean number of bursts (2.05 versus 1.68; p = 0.036) compared to the failed IOLs, but non-significant differences were observed in mean peak frequency, mean burst duration, and mean duration between bursts. ConclusionThe study showed that inductions of labor that took less than 24 h to deliver have a higher mean power in the baseline electrophysiological activity of the uterus when recorded prior to planned induction. The results are indicative that baseline electrophysiological activity measured prior to induction is associated with successful induction.

Abstract 14754: Peak Frequency Mapping in Low Voltage Zones Can Identify the Critical Isthmus in Atypical Atrial Flutters

Introduction: Atypical atrial flutters (AFL) are a heterogeneous group of reentrant arrhythmias and can be challenging to map. Peak frequency (PF) mapping is a novel method of identifying local conductivity and may help identify critical portions of myocardial substrate supporting reentry. Hypothesis: The critical isthmuses of left atrial (LA) AFLs demonstrate a combination of low-voltage and high PF. Methods: LA omnipolar voltage and PF maps were generated using the EnSite Precision Mapping System and HD-Grid catheter in 13 patients undergoing AFL ablation. For the purpose of this study, mapping was performed during AFL and normal voltage was defined as ≥ 0.5 mV, low-voltage (LV) 0.1 - 0.5 mV, and scar &lt; 0.1 mV. PF distributions were analyzed in each tissue type. Conduction velocity (CV) was characterized across PF with correlational analysis. The 1-cm radius from sites of arrhythmia termination with ablation were analyzed to characterize mean PF and voltage in nearby myocardial tissue. Results: Mean age was 65.8 ± 9.3 years and 54% were female. A total of 37,331 points were analyzed. Sites of slow conduction included the mitral isthmus (46%), LA roof (23%), pulmonary vein antra (15%), posterior wall (8%), and anterior wall (8%). In normal voltage tissue, mean PF was 337.7 ± 115.4 Hz. LV and scar tissue had left-skewed PF distributions and lower mean PF ( p &lt; 0.0001). While CV had no trend across PF in tissue with normal voltage ( R 2 , 0.0002 to 0.1), there was moderate conduction slowing at higher PF in LV tissue ( R 2 , 0.07 to 0.30). In PF-LV overlay maps, all termination sites resided in regions of LV and high PF ( Figure ). Of the 1-cm areas neighboring termination, 77% had significantly higher PF than the global LA ( p &lt; 0.05), of which 80% had significantly lower mean voltage ( p &lt; 0.01) or mean voltage &lt; 0.5 mV. Conclusions: Sites of arrhythmia termination can be identified in LV tissue at higher PF. Low-voltage, high-PF areas may be critical targets during catheter ablation of atypical AFL.

Surrounding gas composition affects the calling song development in the two-spotted cricket (Gryllus bimaculatus).

Male crickets emit acoustic signals (i.e., songs) by chirping using their forewings. Although the mechanisms and adaptive functions of these songs are well studied, knowledge about how songs develop within a generation is relatively scarce. Our previous work demonstrated a stable peak frequency at 5.7 kHz in the calling songs recorded from mature adult male crickets (Gryllus bimaculatus). In the present study, we monitored changes in the frequency component over time from the sexual maturity stage (early adult stage). We recorded 300 calling songs from a pool of 122 adults. The peak frequency distribution was lower and unstable (i.e., greater coefficient of variance) in the early adult stage. The mean peak frequency was 4.9 kHz on day 3, but gradually converged to 5.8 kHz over the 2-week adult stage. Immature adult males (emitting immature songs) produced an appropriately tuned song with a peak frequency of 5.8 kHz in an environment of 80% helium and 20% oxygen. These results suggest that the frequency component of the calling song is acquired during the early to mid-adult stage, and may be related to sexual maturation in males. Findings from the helium substitution experiment revealed that physical resistance from surrounding gas molecules negatively affect the stability of male singing, and that muscle development and forewing hardening may contribute to the maturation of singing, suggesting that females may adaptively select sexually mature males based on song traits.