Waveform Duration Research Articles

Coupled Thermal-Mechanical Progressive Damage Model with Strain and Heating Rate Effects for Lightning Strike Damage Assessment

This paper proposes a progressive damage model incorporating strain and heating rate effects for the prediction of composite specimen damage resulting from simulated lightning strike test conditions. A mature and robust customised failure model has been developed. The method used a scaling factor approach and non-linear degradation models from published works to modify the material moduli, strength and stiffness properties to reflect the effects of combined strain and thermal loading. Hashin/Puck failure criteria was used prior to progressive damage modelling of the material. Each component of the method was benchmarked against appropriate literature. A three stage modelling framework was demonstrated where an initial plasma model predicts specimen surface loads (electrical, thermal, pressure); a coupled thermal-electric model predicts specimen temperature resulting from the electrical load; and a third, dynamic, coupled temperature-displacement, explicit model predicts the material state due to the thermal load, the resulting thermal-expansion and the lightning plasma applied pressure loading. Unprotected specimen damage results were presented for two SAE lightning test Waveforms (B & A); with the results illustrating how thermal and mechanical damage behaviour varied with waveform duration and peak current.

Signal Processing Foundations for Time-Based Signal Representations: Neurobiological Parallels to Engineered Systems Designed for Energy Efficiency or Hardware Simplicity

Neurobiological systems operate at power levels that are unattainable by modern electronic systems while exhibiting broader information processing capabilities for a number of important tasks. A variety of engineered systems designed for energy efficiency or hardware simplicity use time-based signal representations, which share similar mathematical principles with those that arise naturally in biology. In general, time-based signal representations refer to embedding information into the timing, density, or duration of a predetermined, and often bipolar, waveform. In mammalian nervous systems, it is generally accepted that neurons embed information into the timing and firing density of the sudden changes in their membrane potential, or spikes. Similarly, many low-power electronic systems use signal representations that embed information in the timing, repetition frequency, or duration of simple pulse waveforms. Despite their apparent similarities, such signal representations are often studied in different contexts.

Estimation of THz field strength by an electro-optic sampling technique using arbitrary long gating pulses

We demonstrate a simple approach to retrieve the original peak electric field (E-field) strength of high-intensity THz pulses using an electro-optic sampling (EOS) technique and the Poynting flux approach. The latter supposes assessment of THz pulse intensity by measurement of pulse energy, duration and spot size, but its applicability to a few-cycle THz pulse needs detailed consideration. We applied a deconvolution procedure to the raw EOS data to retrieve the THz field waveform. We describe a two-step procedure that allows us to assess the field strength of an extreme THz field. First, the EOS measurements of the THz field should be performed at low pulse energies to retrieve the THz waveform and estimate pulse duration and amplitudes of each particular oscillation. Next, the field strength of an extreme THz pulse can be assessed from the Poynting flux approach with correction to the abovementioned data obtained from the EOS measurements. We show good experimental coincidence between peak strength estimation from the EOS directly and from the combined approach at ‘low’ field strength. Hence, an extreme THz E-field strength can also be assessed from preliminary EOS measurements and full energy measurements based on the Poynting flux approach. We also show that the Poynting flux approach for extreme few-cycle THz pulses gives prominent, at least two-fold, underestimation without preliminary EOS measurements.

Waveform complexity: A new metric for EEG analysis

BackgroundEEG represents a cost-effective mechanism to evaluate brain function. To realize its potential, it is essential to identify aspects of the signal that provide insight into differences in cognitive, emotional and behavioral outcomes and can therefore aid in diagnostic measurement. Here we define a new metric of the EEG signal that assesses the diversity of waveform shapes in the signal. New methodThe metric, which we term waveform complexity, abbreviated as Cw, compares the similarity of the shape of waveforms of long durations by computing the correlation (r) of segments. A distribution of waveform diversity is computed as 1-|r|x100, from which Cw is obtained as the median. ResultsWe identify the length parameter that provides the maximal variance in Cw across the sample population and therefore greatest potential discriminatory power. We also provide insight into the impact of various manipulations of the signal such as sampling rate, filtering, phase shuffling and signal duration. Finally, as a test of potential application, we demonstrate that when applied to eyes closed EEG recordings in subjects taken immediately prior to taking a Raven's progressive matrix test, this measure had a high correlation to participant's scores. Comparison with existing methodsCw, while correlated with other similar measures such as spectral entropy, sample entropy and Lempel-Ziv complexity, significantly outperformed these measures in its correlation to participants’ task scores. ConclusionsThis waveform complexity measure warrants further investigation as a potential measure of cognitive and other brain states.

Effect of current pulse duration in recovering quantitative induced polarization models from time-domain full-response and integral chargeability data

The signal level and shape of induced polarization responses are significantly affected by the current pulse duration and waveform. If not accounted for, this data dependency on the current will propagate trough the inversion to results rendering unquantifiable subsurface models. While this problem has been addressed in full-response induced polarization modelling, questions remain as to how to accurately retrieve quantitative induced polarization inversion models from the types of apparent integral chargeability data often used in data interpretation. Although several methodologies have been proposed for handling and inverting apparent resistivity and integral chargeability, these cannot compensate for the data dependency on the current waveform and pulse duration. This paper presents a novel inversion method for such data. The method considers current waveform and receiver transfer functions for retrieving quantitative IP models unbiased by transmitter waveform. The method uses the constant phase angle model, expressed in terms of the medium resistivity and phase. Specifically, four field data sets for the same profile but with different 100 per cent duty cycle pulse durations (4, 2, 1 and 0.5 s) serve as examples of data sets giving models dependant on current waveform when inverted with standard approaches. The novel inversion method presented here gives quantifiable models independent on the current waveform and pulse duration. These results resemble models retrieved with existing, full-response induced polarization inversions. The results still contain some degree of uncertainty in relation to underlying assumptions and parametrizations. Managing this source of uncertainty is considered in terms of full-response induced polarization inversions with constant phase angle and maximum phase angle inversions. (Less)

Unbiased analysis of plethysmography waveforms during opioid‐induced hypoventilation in rats

Whole body plethysmography chambers enable collection of respiratory waveform data from unrestrained and unanesthetized animals. However, the recorded waveforms are dynamically changing and stochastic. Indeed, awake and freely behaving mammals do not breathe with the metronomic patterns studied under anesthesia or in vitro. Typically, in plethysmography experiments, large portions of recorded data are omitted from analysis in favor of arbitrarily defined periods of “stable breathing”. The goals of the current study are 1) to develop a method for unbiased assessment of all waveforms recorded during whole body plethysmography, and 2) to use this method to comprehensively assess breathing patterns following opioid overdose. The rationale being that opioid overdose is a major public health crisis, and many researchers are using rodent models to study the impact of opioids on breathing. We reasoned that detailed analyses of breathing waveforms (i.e., beyond typical assessment of rate and depth) could provide insights into the impact of opioids on the respiratory neuromuscular system. Plethysmography data were recorded from male Sprague Dawley rats (n = 8; 379±24g) using a Buxco Finepointe system. Following an extended period of baseline breathing, fentanyl was administered intravenously until tidal volume was reduced to 50% of baseline values. The required fentanyl dose varied, and ranged from 60–240μg/kg. MATLAB software was written to detect distinct waveforms. Waveforms which crossed a threshold were grouped into four time domains based on duration: 0–0.2s, 0.2–0.5s, 0.5–1.2s, and 1.2–4s. Principle component analysis reduced the dimensionality, and a hierarchical linkage tree was constructed to group the waveforms into clusters. Within each time domain the linkage tree was restricted to 2, 5, 5, and 3 clusters based on the expected variability of breath shapes within each time domain. These waveforms encompassed respiratory‐related behaviors including sniff, tidal breathing, and sigh. We next quantified the frequency of these 15 waveforms during baseline, the entire period of fentanyl infusion (F‐entire), and during the last 5‐min of the fentanyl exposure when ventilation was at its nadir (F‐end). During F‐end, the larger amplitude, short time scale waveform occurred 8% as often compared to baseline. The occurrence of four of the five 0.2–0.5s duration waveforms was reduced during F‐end; however, we also observed a 209% increase in the occurrence of a distinct low amplitude waveform. Similarly three of the five waveforms in the 0.5–1.2s time domain occurred less often during F‐end, one was unchanged and the incidence of one waveform increased by 4446%. Interestingly, the incidence of this cluster during F‐entire increased by 1938% suggesting the presence of this waveform could indicate oncoming respiratory decline. We conclude that respiratory waveform cluster analysis allows for rapid unbiased assessment of breathing patterns during instances of hypoventilation. This analysis can provide insight into how the neuromotor respiratory system is affected by drugs, disease, or injury.Support or Funding InformationT32‐HD043730 (MDS). SPARC OT2 OD0238541 R01 NS080180‐01A1 (DDF)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

A Lamb wave signal reconstruction method for high-resolution damage imaging

In Lamb wave-based Structural Health Monitoring (SHM), a high-enough spatial resolution is highly required for Lamb wave signals to ensure the resolution and accuracy of damage detection. However, besides the dispersion characteristic, the signal spatial resolution is also largely restricted by the space duration of excitation waveforms, i.e., the Initial Spatial Resolution (ISR) for the signals before travelling. To resolve the problem of inferior signal spatial resolution of Lamb waves, a Lamb Wave Signal Reconstruction (LWSR) method is presented and applied for high-resolution damage imaging in this paper. In LWSR, not only a new linearly-dispersive signal is reconstructed from an original Lamb wave signal, but also the group velocity at the central frequency is sufficiently decreased. Then, both dispersion compensation and ISR improvement can be realized to achieve a satisfying signal spatial resolution. After the frequency domain sensing model and spatial resolution of Lamb wave signals are firstly analyzed, the basic idea and numerical realization of LWSR are discussed. Numerical simulations are also implemented to preliminarily validate LWSR. Subsequently, LWSR-based high-resolution damage imaging is developed. An experiment of adjacent multiple damage identification is finally conducted to demonstrate the efficiency of LWSR and LWSR-based imaging methods.

Manifestations of Cardiovascular Disorders on Doppler Interrogation of the Hepatic Veins

Spectral (pulsed-wave) Doppler interrogation of flow in the hepatic veins (HVs) is a part of any comprehensive echocardiographic examination. Analysis of the direction, velocity, and duration of the Doppler waveforms and their phasic response to respiration allows distinguishing normal from abnormal

Lethal and Sublethal Effects of Neonicotinoid Insecticides on the Adults of Phenacoccus solenopsis (Hemiptera: Pseudococcidae) on Tomato Plants.

Acetamiprid and imidacloprid are two important neonicotinoid insecticides that are widely utilized under field conditions for the management of sucking insect pests, including the solenopsis mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae). Although some information is available regarding their lethal effects, nothing is currently known about the sublethal effects of these insecticides. We, therefore, performed a series of experiments to test the lethal and sublethal effects of these chemicals on oviposition duration and fecundity. We also assessed sublethal effects on feeding behavior using the electrical penetration graph (EPG) technique. The results of this study reveal that acetamiprid toxicity is higher than imidacloprid and that both insecticides have negative effects on the oviposition, fecundity, and feeding behavior of P. solenopsis when applied at sublethal dosages. These chemicals also significantly reduce oviposition duration and fecundity and significantly prolong nonprobing duration, increase penetration problems, and reduce phloem and xylem feeding activities when compared with adults exposed to just water. No significant differences were detected in all waveform durations and events when adults previously exposed to foliage treated with each of these two insecticides were compared. The results of this study, therefore, suggest that both insecticides are capable of protecting crops from mealybug damage by not only killing these pests directly but also reducing their fecundity and inhibiting feeding behaviors when applied at sublethal dosages.

A signal domain transform method for spatial resolution improvement of Lamb wave signals with synthetically measured relative wavenumber curves

In practical structural health monitoring with Lamb waves, the signal spatial resolution is usually restricted by not only dispersion but also the space duration of excitation waveforms, that is, the initial spatial resolution for the signals before traveling. As a result, the final resolution and accuracy of damage identification could be badly impaired. To overcome this problem, a signal domain transform method is presented in this article. In signal domain transform, the original dispersive Lamb wave signals are transformed from the time to distance domains, with the time–distance scaling on the excitation waveforms particularly modified. Then, both dispersion compensation and initial spatial resolution enhancement can be actualized to efficiently improve the signal spatial resolution. Considering the practical situation that the structural property parameters could be unavailable to theoretically derive the requisite wavenumber relations, signal domain transform with synthetically measured relative wavenumber curves is further explored. After the frequency domain representation and spatial resolution of Lamb wave signals are basically analyzed, the principle and numerical realization of signal domain transform are investigated. Hereafter, the synthetic measurement of relative wavenumber curves for signal domain transform is discussed and preliminarily validated in an aluminum plate. Finally, signal domain transform is applied for high-resolution imaging of adjacent multiple damages. The efficiency of signal domain transform and signal domain transform–based imaging methods has been well demonstrated by the experimental study on a glass fiber–reinforced composite plate with unknown material parameters.

Effect of compression waveform and resuscitation duration on blood flow and pressure in swine: One waveform does not optimally serve

BackgroundChest compression (CC) research primarily focuses on finding the ‘optimum’ compression waveform using a variety of compression efficacy metrics. Blood flow is rarely measured systematically with high fidelity. Using a programmable mechanical chest compression device, we studied the effect of inter-compression pauses in a swine model of cardiac arrest, testing the hypothesis that a single ‘optimal’ CC waveform exists based on measurements of resulting blood flow. MethodsHemodynamics were studied in 9 domestic swine (∼30 kg) using multiple flow probes and standard physiological monitoring. After 10 min of ventricular fibrillation, five mechanical chest compression waveforms (5.1 cm, varying inter-compression pauses) were delivered for 2 min each in a semi-random pattern, totaling 50 compression minutes. Linear Mixed Models were used to estimate the effect of compression waveform on hemodynamics. ResultsBlood flow and pressure decayed significantly with time in both arteries and veins. No waveform maximized blood flow in all vessels simultaneously and the waveform generating maximal blood flow in a specific vessel changed over time in all vessels. A flow mismatch between paired arteries and veins, e.g. abdominal aorta and inferior vena cava, also developed over time. The waveform with the slowest rate and shortest duty cycle had the smallest mismatch between flows after about 30 min of CPR. ConclusionsThis data challenges the concept of a single optimal CC waveform. Time dependent physiological response to compressions and no single compression waveform optimizing flow in all vessels indicate that current descriptions of CPR don’t reflect patient physiology.

Methods for measuring swallowing pressure variability using high-resolution manometry.

Any movement performed repeatedly will be executed with inter-trial variability. Oropharyngeal swallowing is a complex sensorimotor action, and swallow-to-swallow variability can have consequences that impact swallowing safety. Our aim was to determine an appropriate method to measure swallowing pressure waveform variability. An ideal variability metric must be sensitive to known deviations in waveform amplitude, duration, and overall shape, without being biased by waveforms that have both positive and sub-atmospheric pressure profiles. Through systematic analysis of model waveforms, we found a coefficient of variability (CV) parameter on waveforms adjusted such that the overall mean was 0 to be best suited for swallowing pressure variability analysis. We then investigated pharyngeal swallowing pressure variability using high-resolution manometry data from healthy individuals to assess impacts of waveform alignment, pharyngeal region, and number of swallows investigated. The alignment that resulted in the lowest overall swallowing pressure variability was when the superior-most sensor in the upper esophageal sphincter reached half its maximum pressure. Pressures in the tongue base region of the pharynx were least variable and pressures in the hypopharynx region were most variable. Sets of 3 - 10 consecutive swallows had no overall difference in variability, but sets of 2 swallows resulted in significantly less variability than the other dataset sizes. This study identified variability in swallowing pressure waveform shape throughout the pharynx in healthy adults; we discuss implications for swallowing motor control.

Fast self-forced inspirals

We present a new, fast method for computing the inspiral trajectory and gravitational waves from extreme mass-ratio inspirals that can incorporate all known and future self-force results. Using near-identity (averaging) transformations we formulate equations of motion that do not explicitly depend upon the orbital phases of the inspiral, making them fast to evaluate, and whose solutions track the evolving constants of motion, orbital phases and waveform phase of a full self-force inspiral with errors of at most order , where η is the small mass ratio. As a concrete example, we implement these equations for inspirals of non-spinning binaries. Our code computes inspiral trajectories in milliseconds which, depending on the mass-ratio, is a speed up of 2–5 orders of magnitude over previous self-force inspiral models which take minutes to hours to evaluate. Computing two-year duration waveforms using our new model we find a mismatch smaller than ∼10−4 with respect to waveforms computed using slower full self-force models. The speed of our new approach is comparable with kludge models but has the added benefit of easily incorporating self-force results which will, once known, allow the waveform phase to be tracked to sub-radian accuracy over an inspiral.

Pulse shape discrimination based on fast signals from silicon photomultipliers

Recent developments in organic plastic scintillators capable of pulse shape discrimination (PSD) enable a breakthrough in discrimination between neutrons and gammas. Plastic scintillator detectors coupled with silicon photomultipliers (SiPMs) offer many advantages, such as lower power consumption, smaller volume, and especially insensitivity to magnetic fields, compared with conventional photomultiplier tubes (PMTs). A SensL SiPM has two outputs: a standard output and a fast output. It is known that the charge injected into the fast output electrode is typically approximately 2% of the total charge generated during the avalanche, whereas the charge injected into the standard output electrode is nearly 98% of the total. Fast signals from SiPMs exhibit better performance in terms of timing and time-correlated measurements compared with standard signals. The pulse duration of a standard signal is on the order of hundreds of nanoseconds, whereas the pulse duration of the main monopole waveform of a fast signal is a few tens of nanoseconds. Fast signals are traditionally thought to be suitable for photon counting at very high speeds but unsuitable for PSD due to the partial charge collection. Meanwhile, the standard outputs of SiPMs coupled with discriminating scintillators have yielded nice PSD performances, but there have been no reports on PSD using fast signals. Our analysis shows that fast signals can also provide discrimination if the rate of charge injection into the fast output electrode is fixed for each event, even though only a portion of the charge is collected. In this work, we achieved successful PSD using fast signals; meanwhile, using a coincidence timing window of less 3 nanoseconds between the readouts from both ends of the detector reduced the influence of the high SiPM dark current. We experimentally achieved good timing performance and PSD capability simultaneously.

Identification Algorithm of Uncertain Sonar Signals in Complex Marine Environment

Abstract The current identification algorithm using sonar signal parameters of bandwidth, frequency, duration and pulse waveform which are easy to detect and imitation, to identify the identity of sonar signal, resulting in part of the sonar signal identity is not easy to distinguish. Therefore, an algorithm based on signal feature extraction and digital watermarking is proposed to recognize the uncertain sonar signals. The algorithm embeds the digital watermark into the detection signal from the uncertain sonar. The identity of the signal is recognized by detecting whether the received signal contains watermarks. Experimental results showed that the proposed algorithm can effectively improve the recognition performance of sonar signal source.

Use of electrical penetration graphs (EPG) and quantitative PCR to evaluate the relationship between feeding behaviour and Pandora neoaphidis infection levels in green peach aphid, Myzus persicae

A real-time qPCR method was developed, validated, and used to quantity the fungal pathogen, P. neoaphidis, within aphids at different times during infection; colonization rate fitted the Gompertz model well (R2 = 0.9356). Feeding behaviour of P. neoaphidis-infected and uninfected M. persicae were investigated, for the first time, using DC-electrical penetration graphs (DC-EPG) that characterized the waveforms made during different aphid stylet probing periods corresponding to epidermis penetration, salivation and ingestion. In the 6 h following the 12-h incubation period (to achieve infection), there were significant differences in the number of events of Np (non-probing) and C (stylet pathway) between infected and uninfected aphids. However, the difference between total duration of Np and C were not significantly different between infected and uninfected aphids. There were no significant differences in the number of events or total duration of E1 (phloem salivation) or E2 (phloem ingestion) between infected and uninfected aphids. There were significant differences in mean number of events and total duration of the pd waveform (intracellular punctures) in infected and uninfected aphids. In the 16 h prior to death, the same differences in behaviour were observed but they were even more obvious. Furthermore, the total duration time of E2 was significantly greater in uninfected aphids than infected aphids, a change that had not been observed in the first 6 h observation period. In conclusion, qPCR quantification demonstrated ‘molecular’ colonization levels throughout infection, and EPG data analysis during the two periods (during early infection and then during late infection just prior to death) demonstrated the actual physical effects of fungal infection on feeding behaviour of M. persicae; this has the potential to decrease the aphid’s capacity of transmission and dispersal. These studies increase our understanding of the interaction between P. neoaphidis and its host aphid.

Photonic Generation of a Phase-Coded Chirp Microwave Waveform With Increased TBWP

Photonic generation of a phase-coded chirped microwave waveform with an increased time bandwidth product (TBWP) using a frequency-tunable optoelectronic oscillator (OEO) is proposed and experimentally demonstrated. The frequency-tunable OEO is implemented using a tunable laser source (TLS), a phase modulator (PM), a phase-shifted fiber Bragg grating, and a photodetector (PD), with the frequency tuning realized by tuning the wavelength of the TLS. A frequency-tunable optical sideband with a frequency that is equal to that of the optical carrier plus the OEO oscillation frequency is generated by the OEO, which is then orthogonally polarization multiplexed with the optical carrier from the TLS at a polarization beam combiner, and applied to a polarization modulator, to which a binary phase-coded parabolic electrical signal is applied. By beating the two orthogonally polarized optical signals at a PD, a phase-coded chirped microwave waveform is generated. The TBWP is significantly increased due to the increase of the temporal duration of the microwave waveform. The proposed approach is experimentally demonstrated. Two phase-coded chirped microwave waveforms with TBWPs of 58.5 and 80 000 using two phase coding signals corresponding to a 13 Barker code and a 20480-bit pseudorandom sequence are generated.

(Invited) Quantification and Manipulation of the Microelectrode-Tissue Interface for Neural Prostheses

The quality of the information transfer available utilizing a chronically implanted neural interface likely depends upon the quality of the electrode-tissue interface. High density, high-fidelity neural interfaces require small electrode site areas; unfortunately, these electrodes typically have high initial impedances, as well as exhibit impedance drift post-implant. Here we will discuss our efforts to elucidate and control this electrochemical effect. One mechanism to address initial high-impedance microelectrode interfaces is by applying surface coatings to the metal sites. In this report we quantify the in vitro stability and in vivoperformance of poly(3,4-ethylenedioxythiophene) (PEDOT) and compare with iridium oxide (IrOx) for microstimulation applications. Commercially available neural implants (NeuroNexus) with iridium metal sites were either activated to form IrOx or coated with PEDOT. Biphasic current stimulation was then administered in phosphate buffered saline continuously for two hours at the maximum safe level of charge density determined by Shannon (1992). Prior to stimulation, the PEDOT coated sites displayed lower 1 kHz impedances, higher charge storage capacities and lower amplitude voltage excursions than IrOx sites. After stimulation, PEDOT coated sites displayed no significant change in their impedance, cyclic voltammetry (CV) and voltage excursion measurements, while 1 kHz impedance increased and CVs displayed unstable, pulse-induced activation for the IrOx sites. Typically, regardless of surface modification, chronically implanted neural microelectrodes exhibit increases in impedance magnitude, as well as decreases in the signal-to-noise ratio of electrophysiology. Both of these effects are detrimental for microelectrode-based neuroprosthetic systems. It has been suggested that the reactive tissue response to device implantation may be the main cause of these impedance changes. Previously we have used lumped-circuit element models fit to impedance spectroscopy data to estimate several of these device-tissue interface parameters. Further, we have utilized brief voltage pulses to affect these parameters for a period on the order of hours. One method shown to temporarily mitigate this response and thus improve the interface quality is delivery of a short-duration DC bias voltage to the electrode site (Johnson et al. 2005; Otto et al. 2006). While this method has successfully recovered electrical signals from the interface, other research demonstrates that application of a charge-imbalanced waveform may be harmful to the electrode or electrode-tissue interface. Here, we report the effect of applying charge-balanced sinusoidal AC waveforms on the electrode-tissue interface. We utilized impedance spectroscopy as well as cyclic voltammetry in order to quantify the interface. We use in vitro experiments using 0.9% phosphate buffered saline, varying waveform amplitude, duration, and frequency. In vitro results suggest that, within-limits, charge-balanced waveforms are safer for application of electrical pulses. Subsequent in vivo experiments were conducted using chronically implanted male Long-Evans rats, and cyclic voltammetry, impedance spectroscopy, and electrophysiology measurements were performed.

Maturation Modulates Pharyngeal-Stimulus Provoked Pharyngeal and Respiratory Rhythms in Human Infants.

Pharyngeal-provocation induced aerodigestive symptoms in infants remain an enigma. Sources of pharyngeal provocation can be anterograde as with feeding, and retrograde as in gastroesophageal reflux. We determined maturational and dose-response effects of targeted pharyngeal-stimulus on frequency, stability, and magnitude of pharyngeal and respiratory waveforms during multiple pharyngeal swallowing responses in preterm-born infants when they were of full-term postmenstrual age (PMA). Eighteen infants (11 male) were studied longitudinally at 39.8±4.8 weeks PMA (time-1) and 44.1±5.8 weeks PMA (time-2). Infants underwent concurrent pharyngo-esophageal manometry, respiratory inductance plethysmography, and nasal airflow thermistor methods to test sensory-motor interactions between the pharynx, esophagus, and airway. Linear mixed models were used and data presented as mean±SEM or %. Overall, responses to 250 stimuli were analyzed. Of the multiple pharyngeal swallowing responses (n=160), with maturation (a) deglutition apnea duration decreases (p<0.01), (b) number of pharyngeal waveform peaks and duration decreases for initial responses (p<0.01), and subsequent responses have lesser variation and greater stability (p<0.01). With increment in stimulus volumes we noted (a) increased prevalence (%) of pharyngeal responses (p<0.05), (b) increased number of pharyngeal peaks (p<0.05), yet pharyngeal frequency (Hz), variability, and stability remain unaffected (p>0.05), and (c) respiratory changes were unaffected (p>0.05). Initial and subsequent pharyngeal responses and respiratory rhythm interactions become more distinct with maturation. Interval oromotor experiences and volume-dependent increase in adaptive responses may be contributory. These mechanisms may be important in modulating and restoring respiratory rhythm normalcy.

Physical and electrocardiographic evaluation of horses used for wagon traction

ABSTRACT The objective of this research was to evaluate the electrocardiogram (ECG) of horses used for wagon traction and to compare the results with the parameters obtained from inactive horses or horses submitted to a training routine. Fifty-six 3-15-year-old healthy horses (22 females and 34 males) were divided into three groups: control (without a work routine; N=21), wagon traction (N=25) and athlete (N=10) and submitted to physical examination and ECG (at rest). The rhythm, heart rate (HR), amplitude and duration of ECG waveforms and intervals were obtained from the frontal plane and base-apex leads. Heart score (HS) was calculated using the arithmetic mean of QRS duration in LI, LII and LIII. Measurements of ECG waves were smaller in control group, in comparison with wagon traction and athlete groups, suggesting that exercise can change ECG. Similar results were observed in the wagon traction and athlete groups, but the electrophysiological adjustments to exercise were not the same for these groups.