Pulse Transmission Research Articles

Dynamics of influenza transmission in vampire bats revealed by longitudinal monitoring and a large-scale anthropogenic perturbation.

Interrupting pathogen transmission between species is a priority strategy to mitigate zoonotic threats. However, avoiding counterproductive interventions requires knowing animal reservoirs of infection and the dynamics of transmission within them, neither of which are easily ascertained from the cross-sectional surveys that now dominate investigations into newly discovered viruses. We used biobanked sera and metagenomic data to reconstruct the transmission of recently discovered bat-associated influenza virus (BIV; H18N11) over 12 years in three zones of Peru. Mechanistic models fit under a Bayesian framework, which enabled joint inference from serological and molecular data, showed that common vampire bats maintain BIV independently of the now assumed fruit bat reservoir through immune waning and seasonal transmission pulses. A large-scale vampire bat cull targeting rabies incidentally halved BIV transmission, confirming vampire bats as maintenance hosts. Our results show how combining field studies, perturbation responses, and multi-data-type models can elucidate pathogen dynamics in nature and reveal pathogen-dependent effects of interventions.

500 Mbps high-speed high-sensitivity photon-counting communication demonstration system

We propose and demonstrate a high-speed, high-sensitivity photon communication system based on a 16-pixel superconducting nanowire single-photon detector (SNSPD) array. This system integrates high-speed transmission of narrow optical pulses and multi-channel array high-speed signal detection and reception. By incorporating the proposed channel log-likelihood ratio correction and high-speed slot synchronization algorithm, the system's performance is enhanced. Experimental results demonstrate that the system exhibits leading photon sensitivity and high-speed communication performance. It achieves a post-decoding bit error rate (BER) better than 10−7 at an effective information transmission rate of up to 500 Mbps, with an incident sensitivity of 1.78 photons/bit and a detection sensitivity of 0.97 photons/bit. Furthermore, the system is capable of maintaining closed-loop BER performance within a dynamic range of at least 1.8 dB above this incident signal level, highlighting the advanced performance and reliability of the entire system. Additionally, the system supports 10 G/40 G ethernet interfaces, enabling inter-board timestamp data transmission from the time-to-digital converter (TDC) to the FPGA at rates between 300 million and 1.2 billion timestamps per second, indicating potential for rapid real-time hardware implementation. This demonstration system can provide insights for the design of future high-speed real-time photon counting communication systems.

An improved method to accelerate the acquisition efficiency of the T1-T2 spectrum based on the IR-BSSFP-CPMG pulse sequence

The correlation map of the longitudinal relaxation time (T1) and the transverse relaxation time (T2) offers valuable information of different proton contributions and is served as a significant data for identifying, quantifying and characterizing complex relaxation components in unconventional reservoirs. However, the acquisition speed and spectral resolution for existing pulse sequences cannot be guaranteed simultaneously. We designed an improved pulse sequence which integrates the inversion recovery-balanced steady-state free precession (IR-BSSFP) sequence and the Carr-Purcell-Meiboom-Gill (CPMG) sequence, allowing for the measurement of two-dimensional T1-T2 spectrums. The IR-BSSFP sequence adopts a low refocusing angle and reduced flip angle pulse transmission power, eliminating the need for complete polarization. Moreover, the parameters of the improved pulse sequence such as the value and the number of the flip angle, the repetition time are discussed by numerical simulations. The result showed that the new pulse sequence achieves high-precision measurement performance, and the T1-T2 spectrum can be achieved within a few seconds.

Towards neuromorphic compression based neural sensing for next-generation wireless implantable brain machine interface

Abstract This work introduces a neuromorphic compression based neural sensing architecture with address-event representation inspired readout protocol for massively parallel, next-gen wireless implantable brain machine interface (iBMI). The architectural trade-offs and implications of the proposed method are quantitatively analyzed in terms of compression ratio and spike information preservation. For the latter, we used metrics such as root-mean-square error and correlation coefficient between the original and recovered signals to assess the effect of neuromorphic compression on the spike shape. Furthermore, we use accuracy, sensitivity, and false detection rate to understand the effect of compression on downstream iBMI tasks, specifically, spike detection. We demonstrate that a data compression ratio of 15-265 per channel can be achieved by transmitting address-event pulses for two different biological datasets. The compression ratio increases to 200-50K per channel, 50× more than in prior works, by selective transmission of event pulses corresponding to neural spikes. A correlation coefficient of ∼0.9 and spike detection accuracy of over 90% were obtained for the worst-case analysis involving 10K-channel simulated recording and typical analysis using 100 or 384-channel real neural recordings. We also analyzed the collision handling capability for up to 10K channels and observed no significant error, indicating the scalability of the proposed pipeline. We also present initial results to show the ability of intention decoders to work directly on the events generated by the neuromorphic front-end.

A Field Trial to Study the Effects of Stenella attenuata Deterrent on the Catch of a Light-Falling Net Fishery

The incidental capture (bycatch) of protected cetaceans in fishing gear has become a serious problem worldwide. Bycatch has also had many serious consequences for pantropical spotted dolphins (Stenella attenuata) in the light-falling net fishery within this research area. We provided a self-developed acoustic deterrent device and conducted trials to investigate the long-term deterrent effects on Stenella attenuata and assess the influence of external factors on fishing catch. In 2022, 50 deterrence trials were conducted, of which 38 were effective and 12 were ineffective. In 2023, 30 deterrence trials were conducted: 24 effective and 6 ineffective. No dolphin bycatch occurred within a two-year period. Overall, the catch per unit effort (CPUE) of the effective deterrence nights was 4.96 ± 3.06 kg/min, while the CPUE of the ineffective nights was 3.78 ± 3.10 kg/min. There was a significant difference (p = 0.041, >0.05) between the two conditions. On the nights when dolphins did not appear, the average CPUE was 5.04 ± 4.44 kg/min. This CPUE was not different from the night on which deterrence was successful (p = 0.981, >0.05), but was considerably higher than night on which deterrence was unsuccessful (p = 0.028, <0.05). General additive model results indicate that month, longitude, flow direction, latitude, wind direction, dolphin number, and wind speed affect fish catch. The ADD may be improved by manually controlling the pulse frequency, transmission interval, and type to improve deter efficiency.

Research on pulse transmission dynamics in optical fiber based on intelligence algorithms

Research on pulse transmission dynamics in optical fiber based on intelligence algorithms

Tunable FSRS measurements with reduced background signals: Using an etalon filter to generate picosecond pump pulses in the 460-650nm range.

Generating wavelength-tunable picosecond laser pulses from an ultrafast laser source is essential for femtosecond stimulated Raman scattering (FSRS) measurements. Etalon filters produce narrowband (picosecond) pulses with an asymmetric temporal profile that is ideal for stimulated resonance Raman excitation. However, direct spectral filtering of femtosecond laser pulses is typically limited to the laser's fundamental and harmonic frequencies due to very low transmission of broad bandwidth pulses through an etalon. Here, we show that a single etalon filter (15cm-1 bandwidth; 172cm-1 free spectral range) provides an efficient and tunable option for generating Raman pump pulses over a wide range of wavelengths when used in combination with an optical parametric amplifier and a second harmonic generation (SHG) crystal that has an appropriate phase-matching bandwidth for partial spectral compression before the etalon. Tuning the SHG wavelength to match individual transmission lines of the etalon filter gives asymmetric picosecond pump pulses over a range of 460-650nm. Importantly, the SHG crystal length determines the temporal rise time of the filtered pulse, which is an important property for reducing background and increasing Raman signals compared with symmetric pulses having the same total energy. We examine the wavelength-dependent trade-off between spectral narrowing via SHG and the asymmetric pulse shape after transmission through the etalon. This approach provides a relatively simple and efficient method to generate tunable pump pulses with the optimum temporal profile for resonance-enhanced FSRS measurements across the visible region of the spectrum.

Laser interaction with undercritical foams of different spatial structures

The interaction of high-power laser pulses with undercritical foams produced by different techniques but with the same average density is studied at the PALS laser facility. The spatial–temporal evolution of X-ray emission is observed using an X-ray streak camera, electron and ion temperatures are measured by X-ray spectroscopy, and hot-electron production is characterized by monochromatic X-ray imaging. Transmission of a femtosecond laser probe pulse through foams is observed in the near and far fields. In spite of large differences in pore size and foam structure, the velocity of ionization front propagation is quite similar for all the foams studied and is slower than that in a homogeneous material of the same average density. The ion temperature in the plasma behind the ionization front is a few times higher than the electron temperature. Hot-electron production in plastic foams with small pores is strongly suppressed compared with that in solid targets, whereas in foams produced by additive manufacturing, it is significantly increased to the level observed in bare copper foil targets.

Studies of gas ionization by high-power, sub-nanosecond microwave pulses

This study investigates the ionization pressure threshold of a gas (air, helium, argon, and SF6 across a wide pressure range) filled dielectric tube when a ∼300 MW, ∼0.7 ns, 9.6 GHz high-power microwave (HPM) pulse propagates through it. The thresholds are determined as the pressure for which the energy of the transmitted HPM pulse decreases to ∼30%, which is close to the same HPM pulse's transmission coefficient when a metal rod fills the tube. These thresholds are found to be 0.4 × 105 Pa,105 Pa, 1.8 × 105 Pa, and 0.2 × 105 Pa, for air, argon, helium, and SF6, respectively. The measured intensity of the plasma light emission starts to decrease at a pressure which coincides with the pressure threshold determined by HPM pulse propagation. Additionally, at gas pressures <5 × 104 Pa, it is shown that time- and space-resolved images of the light emission display a diffused plasma which at higher pressures >105 Pa transforms into streamer like plasma. Simplified numerical simulations of a microwave discharge in air at 1 × 105 Pa and 4 × 105 Pa are consistent with the experimental plasma light observations.

Experimental study on dissipative characteristics of cathode plasma of coaxial magnetically insulated transmission lines based on microwave interferometry

Flash x-ray radiography is an important diagnostic in hydrodynamic experiments to provide fluoroscopic imaging of fast-moving dense targets. In order to obtain multiple images of an object at different times in an experiment, a flash x-ray accelerator is required to output multiple pulses. For the induction voltage adder (IVA) multi-pulse accelerator, it is important to study the effect of the cathode plasma generated by the front pulse in magnetically insulated transmission lines (MITLs) on the transmission of the subsequent pulses. In this paper, a coaxial MITL experimental platform based on the “QiangGuang-I” accelerator is established to study the dissipation characteristics of the cathode plasma, and its working condition is similar to that of MITLs in typical IVA accelerators. In the experiment, a stable magnetic insulation is formed in the coaxial MITL, and the current loss along the line can be ignored. The microwave interferometer is used to measure the evolution of cathode plasma density over time for hundreds of microseconds after the pulse disappears. The measurement results of microwave interference show that the line-averaged density of the plasma in the anode–cathode gap is above 1 × 1018 m−3, and the time for the plasma density to decrease to 1 × 1016 m−3 is about 600 μs. The expansion velocity of the plasma after a pulse is much lower than that during the pulse. In addition, the dissipation characteristics of the cathode plasma with different electrical parameters of the pulses are compared and analyzed.

Study of structural, elastic, optical, dielectric, and magnetic properties of sol-gel synthesized Li0.2Co0.3Zn0.3Fe2.2O4 ferrite for optoelectronic and electrical applications

This work presents a detailed investigation of the structural, elastic, optical, dielectric, and magnetic properties of Li0.2Co0.3Zn0.3Fe2.2O4 ferrite synthesized through the sol-gel process. The experimental structural parameters closely match the theoretical values, confirming the proposed cation distribution of the prepared sample. The FTIR spectrum and ultrasonic pulse transmission method analysis showed that the sample has brittle mechanical properties. According to UV-Vis optical absorbance analyses and based on Tauc's law, the sample exhibits a direct optical transition, with the band gap energy (Eg) determined to be 2.51 eV. The study of electrical conductivity showed that the sample exhibited a reduced activation energy (Ea= 0.154 eV) and remarkable electrical resistivity at room temperature (ρdc ∼ 104 Ω.m), indicating the material's potential for microwave device applications. The conduction process of the sample aligns with the NSPT model. Additionally, the temperature coefficient of resistance (TCR) suggests that the sample is a promising candidate for infrared radiation detection. A low coercive field was also derived from the hysteresis loop, confirming the soft nature of the sample operating within a microwave frequency range of 8–9 GHz. Our results show that the Li0.2Co0.3Zn0.3Fe2.2O4 compound offers advantages over the undoped Li0.5Fe2.5O4 compound, including a lower band gap, reduced activation energy, and higher electrical resistivity. This suggests that substituting Co and Zn into Li0.5Fe2.5O4 ferrites improves their performance in electrical and optoelectronic applications.

Study of the parametric effect of the wave profiles of the time-space fractional soliton neuron model equation arising in the topic of neuroscience

Time-space fractional nonlinear problems (T-SFNLPs) play a crucial role in the study of nonlinear wave propagation. Time-space nonlinearity is prevalent across various fields of applied science, nonlinear dynamics, mathematical physics, and engineering, including biosciences, neurosciences, plasma physics, geochemistry, and fluid mechanics. In this context, we examine the time-space fractional soliton neuron model (TSFSNM), which holds significant importance in neuroscience. This model explains how action potentials are initiated and propagated by axons, based on a thermodynamic theory of nerve pulse transmission. The signals passing through the cell membrane (CM) are proposed to take the form of solitary sound pulses, which can be represented as solitons. To investigate these soliton solutions, nonlinear fractional differential equations (NLFDEs) are transformed into corresponding partial differential equations (PDEs) using a fractional complex transform (FCT). The Kudryashov method is then applied to determine the wave profiles for the TSFSNM equation. We present 3D, 2D, contour, and density plots of the TSFSNM equation, and further analyze how fractional and time-space parameters influence these wave profiles through additional graphical representations. Kink, singular kink and different types of soliton solutions are successfully recovered through the Kudryashov method. The outcomes of various studies show that the applied method is highly efficient and well-suited for tackling problems in applied sciences and mathematical physics. Graphical representations, coupled with numerical data, reinforce the validity and accuracy of the technique. The proposed method is a convenient and powerful tool for handling the solution of nonlinear equations, making it particularly effective in exploring complex wave phenomena in diverse scientific fields.

Pseudospin-polarized slow light waveguides with large delay-bandwidth product

Delay-bandwidth product (DBP) is a key metric in slow light waveguides, requiring a balance between a large group index and broad bandwidth—two parameters that often involve a trade-off. Here, we propose and demonstrate a slow light waveguide with large DBP using a pseudospin-polarized transverse electromagnetic mode. This waveguide features a folded edge configuration that supports a 200% relative bandwidth from quasistatic limit (zero frequency) and an arbitrarily large group index. Owing to the pseudospin-polarized design, the dense folding would not introduce backscattering and the associated group velocity dispersion (GVD). The resulting gapless linear dispersion and pulse transmission behavior in folded edge waveguide are observed in microwave experiments. Our scheme provides a way to overcome the trade-off between group index and working bandwidth in slow light waveguide, which has potential applications in broadband optical buffering, light-matter interaction enhancement, terahertz radiation source and time domain processing.

Effects of Humidity on Mycelium-Based Leather.

Leather is a product that has been used for millennia. While it is a natural material, its production raises serious environmental and ethical concerns. To mitigate those, the engineering of sustainable biobased leather substitutes has become a trend over the past few years. Among the biobased materials, mycelium, the fungal "root" of a mushroom, is one of the promising alternatives to animal leather, as a material with tunable physicomechanical properties. Understanding the effect of humidity on mycelium-based leather material properties is essential to the production of durable, competitive, and sustainable leather products. To this end, we measured the water sorption isotherms on several samples of mycelium-based leather materials and investigated the effects of water sorption on their elastic properties. The ultrasonic pulse transmission method was used to measure the wave speed through the materials while measuring their sorption isotherms at different humidity levels. Additionally, the material's properties were mechanically tested by performing uniaxial tensile tests under ambient and immersed conditions. An overall reduction in elastic moduli was observed during both absorption and immersion. The changes in the measured longitudinal modulus during water sorption reveal changes in the elasticity of the test materials. The observed irreversible variation of the longitudinal modulus during the initial water sorption can be related to the material production process and the presence of various additives that affect the mechanical properties of the leather materials. Our results presented here should be of interest to material science experts developing a new generation of sustainable leather products.

Pulse transmission time and amplitude of digital pulse wave determined by fingertip plethysmography as a surrogate marker of brachial artery flowmediated dilatation.

To assess the changes in blood vessel stiffness and digital pulse wave amplitude because of flowmediated dilatation, and to explore how these two variables change when endothelial dysfunction is experimentally induced. The experimental study was conducted at the departments of physiology at the College of Medicine, Mustansiriyah University, and the College of Medicine, Al-Iraqia University, Baghdad, Iraq, from October 14, 2021, to May 31, 2022, and comprised healthy young males who were subjected to the flow-mediated dilatation technique on the left brachial artery. Pulse transit time and the amplitude of the digital pulse wave were measured during reactive hyperaemia for 2.5 minutes from the left middle finger using a piezoelectric pressure sensor and a simultaneous Lead I electrocardiogram. Endothelial dysfunction (ED) was induced by oscillatory and retrograde shear rates. The correlation between variables was calculated in Excel running on the Windows operating system. There were 10 second-year medical students with mean age 22±0 years and mean body mass index 25.7±4.8kg/m2. During reactive hyperaemia, pulse transit time was significantly increased by 3-5% in both normal endothelium and experimentally induced endothelial dysfunction relative to the pre-occluded artery, and the difference was not significant (p>0.05). Digital pulse wave amplitude increased significantly in normal endothelium relative to the pre-occluded artery (p<0.05), but not in experimentally-induced endothelial dysfunction (p>0.05). The pulse transit time and digital pulse wave amplitudes of the photo plethysmography signal may be used to detect changes in vessel wall diameter and tone throughout the reactive hyperaemia process. Digital pulse wave amplitude was better able to detect experimentally-induced endothelial dysfunction, as assessed by the flowmediated dilatation protocol, than pulse transit time.

Comparison of two nonlinear formulations of the Maxwell-Cattaneo equation in heat pulse transmission

The nonlinear terms resulting from temperature dependence of thermal conductivity and relaxation time must be considered when studying systems undergoing very short thermal pulses with non-negligible amplitude of the temperature perturbation. Two nonlinear formulations of the Maxwell-Cattaneo-Vernotte equation for thermal transport with relaxation effects are introduced. A comparison of the consequences of these two different nonlinear Cattaneo type equations on thermal pulse propagation is obtained and discussed. The differences in the corresponding velocities and in the corresponding heights of the perturbation peaks turn out to be significant and could be experimentally detected.

Synthesis and analysis of an ensemble of SAR signals

Due to the development of digital technologies for receiving and transmitting radio location signals, the development of modern radars with a synthesized aperture has made it possible to widely use an ensemble of probing signals with periodic sequences of identical pulses. The manipulation of probing pulses in transmission opens up opportunities to reduce the level of interference of ambiguity in range, expand the capture bands, improve azimuth resolution, and reduce interference from the background surrounding the target. However, the literature currently does not sufficiently address the issues of synthesis and analysis of ensembles of probing signals for a synthetic aperture radar (RSA) placed on board an unmanned aerial vehicle. Several variants of the implementation of ensembles of probing signals in the RSA are considered, mathematical modeling and experimental testing are carried out on the basis of the RSA operating in the VHF frequency range, placed on board an unmanned aerial vehicle (UAV). The conducted modeling allows us to draw the following conclusions. The best characteristics are possessed by an ensemble of signals encoded by Huffman codes, where M-sequences were used to "scatter" the roots. In second place is an ensemble of signals encoded by composite M-sequences. However, with an increase in the base of probing signals (N&gt;64), the best results are shown by an ensemble of signals based on composite M-sequences.

Focused Electromagnetic Acoustic Transducers for Lamb Wave Inspection

Abstract Ultrasonic inspection of conductive samples can be performed using electromagnetic acoustic transducers (EMATs). These allow generation of guided waves, such as Lamb waves, in thin plates. Lamb waves are used for defect screening as they can travel long distances with relatively little attenuation. However, large wavelengths are used, which results in poor sensitivity to subwavelength sized defects. This work presents methods for using Lamb waves to detect smaller defects. Curved, geometrically focused EMATs were used to generate and detect Lamb waves in a 1 mm thick aluminum plate. The focal spot of these EMATs is investigated and the dependence of the focal spot dimensions and locations on the wavelength of the generation signal are presented. An array of geometrically focused detection EMATs was used to measure a 10×10×0.5mm square machined defect, simulating wall thinning. Perturbations in the pulse transmission in the region of the defect were detected, along with reflections, with each detector in the array sensitive to different defect features. B-scans and C-scans are presented utilizing these perturbations and reflections to locate, size, and image the machined defect. Analysis of data from the B-scan is shown to accurately size the defect width to within ±0.73mm. Very good agreement is shown between the C-scan images and the known location and orientation of the defect. Data fusion techniques are presented to combine data sets from different receiver EMATs and increase the defect detection capability, accuracy, and precision, with the potential for full defect sizing demonstrated.

An integrated dual-frequency IVUS system with interleaved sampling and parallel signal processing based on FPGA

Abstract Due to the lack of high voltage and low frequency pulse transmission channels, commercial high frequency IVUS imaging system cannot meet the hardware requirements of ultrasound angiography. Therefore, it is of great research significance to develop a dual-frequency IVUS rotary imaging system with high integration, high sampling rate and sampling accuracy. In this work, an integrated dual-frequency IVUS system with interleaved sampling and parallel signal processing based on FPGA was developed. The central frequency of low-frequency channel is up to 10MHz, and the peak voltage range is 80-200V. The central frequency of the high-frequency channel is up to 60MHz, and the voltage peak-to-peak range is 40-80V. The acquisition channel is 500MHz and 12bit, which is realized by interleaved sampling of two ADC. The motor controlled ultrasonic transducer acquires 400-800 lines per turn, and eventually form a 360-degree IVUS hybrid imaging successfully.

Heart Pulse Transmission Parameters of Multi-Channel PPG Signals for Cuffless Estimation of Arterial Blood Pressure: Preliminary Study

The paper describes a method developed for the indirect cuffless estimation of arterial blood pressure (ABP) from two/three-channel photoplethysmography (PPG) signals. It is important when the actual ABPs cannot be measured, e.g., during scanning inside a magnetic resonance imager. The proposed procedure uses heart pulse transmission parameters (HPTPs) extracted from the second derivative PPG signals. The linear regression method was used to calculate the relation between the determined HPTPs and the ABPs measured in parallel by a blood pressure monitor. The ABP values were estimated by the inverse conversion characteristic calculated from these linear relations. Three auxiliary investigations were performed first to find appropriate settings for PPG signal processing. We tested the accuracy of ABP estimation using two small corpora of multi-channel PPG records sensed during our previous experiments. We also analyzed the distribution of the determined HPTP values depending on the hand and gender for the mapping of a mutual relationship of HPTPs and measured ABPs. The final estimation errors were evaluated graphically (by correlation scatter plots and Bland–Altman plots) and numerically (by a correlation coefficient between the measured and estimated ABPs and by enumeration of the relative estimation error). The obtained results achieve acceptable mean values of −2.6/−3.5 mm Hg for systolic/diastolic ABPs.