Typical Pulse Research Articles

Persistence or disappearance dynamics of a vector-borne disease model with climate change and distributed delay

This paper is concerned with the dual influences of climate change and distributed delay on dynamics of a vector-borne disease model. Compared to the previous works, the effect of climate change in a latent infection model is first considered since it increases the viral transmission probability of cross species. To deal with the non-monotonicity and heterogeneity of the model, we use some new ideas to investigate the spatio-temporal dynamics. The theoretical analyses suggest that three scenarios will occur as follows (i) If the disease persistence ahead of the climate change, the disease will die out by limiting the propagation speed of susceptible or infected individuals. (ii) The emergence of pulse type epidemic wave is obtained, which means the disease switches rapidly between persistence and disappearance. (iii) If susceptible individuals track the speed of climate change while infected individuals do not, the disease cannot evolve to the endemic disease.

Computational analysis of electrode structure and configuration for efficient and localized neural stimulation.

Neuromodulation technique using electric stimulation is widely applied in neural prosthesis, therapy, and neuroscience research. Various stimulation techniques have been developed to enhance stimulation efficiency and to precisely target the specific area of the brain which involves optimizing the geometry and the configuration of the electrode, stimulation pulse type and shapes, and electrode materials. Although the effects of electrode shape, size, and configuration on the performance of neural stimulation have individually been characterized, to date, there is no integrative investigation of how this factor affects neural stimulation. In this study, we computationally modeled the various types of electrodes with varying shapes, sizes, and configurations and simulated the electric field to calculate the activation function. The electrode geometry is then integratively assessed in terms of stimulation efficiency and stimulation focality. We found that stimulation efficiency is enhanced by making the electrode sharper and smaller. A center-to-vertex distance exceeding 100µm shows enhanced stimulation efficiency in the bipolar configuration. Additionally, the separation distance of less than 1mm between the reference and stimulation electrodes exhibits higher stimulation efficiency compared to the monopolar configuration. The region of neurons to be stimulated can also be modified. We found that sharper electrodes can locally activate the neuron. In most cases, except for the rectangular electrode shape with a center-to-vertex distance smaller than 100µm, the bipolar electrode configuration can locally stimulate neurons as opposed to the monopolar configuration. These findings shed light on the optimal selection of neural electrodes depending on the target applications.

Factors influencing migration of short-finned eels (Anguilla australis) over 3 years from a wetland system, Lake Condah, south-east Australia, downstream to the sea.

Anguillid eel populations are under threat globally. A particularly vulnerable life-cycle stage is the migration of mature adult eels downstream from freshwater habitats through estuaries into the sea to spawn. This study investigated the factors associated with downstream migration of the short-finned eel Anguilla australis (Richardson 1841) from a coastal wetland (Lake Condah) in south-east Australia, using acoustic telemetry. Migration was associated with time of the year, higher water level and river flows, decreasing water temperature, and darker moon phases. Larger individuals and those in better condition were more likely to migrate from the wetland. Downstream migration peaked in spring, in contrast to the typical autumn migration period for other temperate anguillids. Variable responses, in comparison to other studies, highlight how migration cues may not be universal. In south-east Australia, short-finned eels may have evolved to migrate in multiple phases by first migrating to the estuary during typical seasonal spring flow pulses (e.g., to avoid being stranded in upland reaches during dry summer periods) and then migrating into the ocean in autumn. More research is needed to unravel these processes and causes, especially considering that the relationship between migration and hydrology may be complex and confounded (e.g., by human-induced disruptions to migratory pathways).

Differentiating Single Multiple Nanopore Through Conductance Distribution Analysis

AbstractSolid‐state nanopore sensors, a type of resistive pulse sensing, achieve optimal signal‐to‐noise performance with a single nanopore. However, the processes involved in solid‐state nanopore fabrication and subsequent measurements frequently lead to the formation of multiple nanopores, posing a challenge for precise detection. To address this issue, here, a novel and expedient technique to verify the presence of a single nanopore on a chip is developed. The methodology includes measuring the nanopore's conductance in solutions of various salt conditions, followed by a comparison of these results against a theoretical conductance model. This comparison is instrumental in distinguishing between single and multiple nanopores. Additionally, the study delves into various factors that influence the conductance curve, such as deviations in pore shape from the standard circle and inconsistencies in pore diameter. This approach significantly enhances the practical application of low‐cost nanopore preparation techniques, particularly in scenarios like controlled breakdown nanopore fabrication, where the formation of multiple nanopores is a common concern.

Optimization of pulse shape discrimination based on frequency domain for SiPM-based NaIL scintillator detector

Frequency gradient analysis (FGA) neutron-gamma pulse shape discrimination (PSD) based on Fourier transform has proved to be an effective method for discrimination between two types of pulses by simply constructing a discrimination parameter by subtracting the amplitude of the 1st frequency component from the 0th frequency component. However, the discrimination parameter constructed by the above method could not meet the requirements at some lower sample rates, and the dark noise caused using optoelectronic devices such as miniaturized SiPMs array further erodes the difference between the two frequency components. This paper proposes a new discrimination parameter construction method based on FGA for neutron-gamma discrimination, which is referred as mFGA (modified FGA). This discrimination parameter uses the 0th frequency component and other frequency components to enhance the discrimination performance. A neutron detector module consisting of a 25.4 mm× 25.4 mm× 50.8 mm NaI:Tl,6Li (NaIL) scintillator and an array of 8 × 8 SiPMs was established to verify the method of mFGA. The module measured a 252Cf neutron source under three shielding conditions: no shield, 5 cm high-density polyethylene (HDPE), and 10 cm lead brick. The proposed mFGA method was used to calculate the figure of merit (FoM) under each shielding condition and compared to the traditional frequency gradient method (FGA) and the traditional charge comparison method (CCM). The results show that the discrimination performance with the mFGA method is significantly improved. Taking the HDPE shielding group as an example, the performances of the three methods are FoM-FGA =1.14, FoM-mFGA =2.75, FoM-CCM =0.92. At the same time, with the increase of energy, due to the neutron gamma pulse becoming similar, and the discrimination performance of FGA and CCM decrease significantly. The discrimination performance of the mFGA method is relatively stable in all energy regions. Therefore, the proposed method is superior to the traditional FGA of the 0th frequency minus the 1st frequency and has a good application prospect for neutron-gamma discrimination with detectors of poor signal quality.

Plasma evolution in laser powder bed fusion using a double pulse format: Time-resolved measurements and physics-based modeling

A novel laser powder bed fusion (LPBF) process utilizing a special double-pulse format was previously proposed. In this process, typically two different types of laser pulses are fired alternatively in time: the low-intensity “sintering laser pulses” intended to melt and coalesce particles, followed by the high-intensity “pressing laser pulse(s)” intended to induce plasma to generate high pressure onto the powder bed to suppress balling and enhance the densification of the sintered material. Laser-induced plasma plays a key role in the novel double-pulse LPBF process, but has not been studied sufficiently. Some critical questions remain to be better answered, such as: what is the minimum plasma-induced pressure needed to effectively suppress balling and how do the “sintering pulses” influence the plasma evolution? This paper reports a model-experiment integrative study of the plasma in DP-LMS, which is seldom reported in a paper in literature to the authors’ knowledge. The plasma evolution is observed in-situ with a high temporal resolution using an intensified CCD (ICCD) camera. The optical emission spectrum (OES) of the plasma is measured and the plasma temperature is deduced from the OES. A physics-based model for the plasma is developed by combining multiple modules. Under the investigated conditions, the model predictions show acceptable agreements with the measured plasma temperature and top front propagation. Utilizing the model, it has been found that under the conditions studied, the minimum plasma-induced pressure required to effectively suppress balling is approximately the pressure making the Weber number exceed ∼1 for the approximately analogized process of a droplet impacting a solid surface. The effect of the “sintering pulses” also influences the evolution of the plasma and obviously increase the plasma-induced pressure on the powder bed surface.

Chirped self-similar optical solitons with cubic–quintic–septic–nonic form of self-phase modulation

This study investigates the dynamics of ultrashort light pulses in an inhomogeneous optical medium exhibiting all orders of nonlinearity up to the ninth order. The research focuses on exploring the existence and properties of self-similar solitons while varying cubic, quintic, septic, and nonic nonlinearities, group velocity dispersion, and loss or gain. It is found that the transmission system supports the existence of novel types of self-similar bright and dark pulses in the presence of various physical processes. Importantly, these self-similar localized waves exhibit a linear chirp, a crucial factor for achieving effective pulse amplification or compression. Based on the chirp property, the dynamical behaviors of these self-similar waveforms are discussed in a periodically distributed amplification system. The findings highlight that the shape and dynamics of these chirped self-similar pulses can be precisely controlled by selecting appropriate profiles for gain or loss, nonlinearity, and dispersion. Additionally, the research numerically discusses the interaction dynamics between two and three adjacent solitons.

The equivalence of different types of electric pulses for electrochemotherapy with cisplatin - an in vitro study.

Electrochemotherapy (ECT) is a treatment involving the administration of chemotherapeutics drugs followed by the application of 8 square monopolar pulses of 100 μs duration at a repetition frequency of 1 Hz or 5000 Hz. However, there is increasing interest in using alternative types of pulses for ECT. The use of high-frequency short bipolar pulses has been shown to mitigate pain and muscle contractions. Conversely, the use of millisecond pulses is interesting when combining ECT with gene electrotransfer for the uptake of DNA-encoding proteins that stimulate the immune response with the aim of converting ECT from a local to systemic treatment. Therefore, the aim of this study was to investigate how alternative types of pulses affect the efficiency of the ECT. We performed in vitro experiments, exposing Chinese hamster ovary (CHO) cells to conventional ECT pulses, high-frequency bipolar pulses, and millisecond pulses in the presence of different concentrations of cisplatin. We determined cisplatin uptake by inductively coupled plasma mass spectrometry and cisplatin cytotoxicity by the clonogenic assay. We observed that the three tested types of pulses potentiate the uptake and cytotoxicity of cisplatin in an equivalent manner, provided that the electric field is properly adjusted for each pulse type. Furthermore, we quantified that the number of cisplatin molecules, resulting in the eradication of most cells, was 2-7 × 107 per cell. High-frequency bipolar pulses and millisecond pulses can potentially be used in ECT to reduce pain and muscle contraction and increase the effect of the immune response in combination with gene electrotransfer, respectively.

Experiment and numerical simulation on the performance of multiple unidirectional single‐particle dampers under seismic excitation

AbstractThis study designed and manufactured a 1/5‐scale model of a three‐story steel frame structure. Various types of ground motions, including non‐long period (NLP) ground motions, near‐fault pulse type (NFPT) ground motions, and non‐pulse long‐period (NPLP) ground motions, were selected following the site conditions of the structure. The multiple unidirectional single‐particle damper (MUSPD) and its layout schemes were then designed. A series of shaking table tests for the three‐story steel frame with and without MUSPD were performed. Subsequently, a mechanical model of the multi‐degree‐of‐freedom structure with MUSPDs was established, and a corresponding numerical simulation method was proposed. The results revealed that MUSPDs achieved an average damping rate of 18.24% for peak and 27.41% for Root Mean Square (RMS). Notably, MUSPD exhibited a superior damping effect on the RMS of the structure compared to the peak. The distributing floor particle mass according to the first‐order mode of the structure resulted in excellent damping performance. Additionally, determining the particle movement distance for each floor involved calculating the optimal distance using a single‐degree‐of‐freedom structure. MUSPDs exhibited a better damping effect under NLP ground motions compared to NFPT and NPLP ground motions. The shaking table test results confirmed the rationality and feasibility of the proposed numerical simulation method, demonstrating a high level of accuracy.

Simultaneous generation of wavelength multiplexing and polarization multiplexing from a wavelength-tunable ultrafast fiber laser

A wavelength-tunable mode-locked erbium-doped all-fiber laser delivering both wavelength multiplexing and polarization multiplexing asynchronous pulses is experimentally demonstrated, which is challenging in previous studies. The numerical simulations validate the experimental observations and reveal that the cavity birefringence and polarization dependent loss (PDL) induced by the wavelength division multiplexer play a significant role in the formation of different types of asynchronous pulses. Our results not only provide insights into the physical mechanism of the asynchronous pulses generation, but also offer a potential low-complexity light source for dual-comb applications.

Use of malted pulses to formulate gluten-free fresh-egg pasta

In spite of the fact that legumes are rich in proteins, dietary fibers, and micronutrients, their average per capita consumption is limited because of their lengthy cooking period, unpleasant flavor, low-digestible proteins, and gastrointestinal problems. This study was aimed at assessing the effectiveness of the malting process of three typical pulse seeds of the Italian Latium region (i.e. Gradoli Purgatory beans [GPB]; Onano lentils [OL]; and Solco Dritto chickpeas [SDC]) to minimize their anti-nutrient content and test their use as ingredient in the preparation of gluten-free fresh egg pastas. All these fresh egg pastas were devoid of flatulence-inducing oligosaccharides with low phytate content (0.6–0.80 g/100 g of dry matter, dm), a crude protein content of around 20 g/100 g dm and in vitro glycemic index ranging from 28% to 38%. However, the only fresh egg pasta, including malted GPB flour, exhibited not only a significantly smaller glycemic index (28%±3%) but also a resistant starch–total starch ratio by far greater than the threshold value (14%) specified by the European Commission Regulation 432/2012 to label foods with the health claim indicating improvement in postprandial glucose metabolism.

Predicting the Type of Narrow Bipolar Pulse: A Machine Learning Approach

Narrow Bipolar Pulses (NBP) depicts the electric field (E-Field) changes due to a Compact Intra-cloud Discharge (CID) and are of two types namely Positive NBP (PNBP) and Negative NBP (NNBP). In this study, 437 NBPs were statistically investigated using a dataset collected in Sri Lanka in 2013, 2015, 2016 and 2017. Seven independent variables (Pulse Duration (PD), Rise Time (RT), Slow Front Duration (SFD), Zero Crossing Time (ZCT), Full Width at Half Maximum (FWHM) and Ratio between the Initial and Overshoot Peak Amplitudes (RIOPA)) and one dependent variable (Type of NBP) were analyzed. Two machine learning classification models, the Random Forest (RF) model and the Binary Logistic Regression (BLR) model, were used to predict the dependent variable based on the independent variables. Two models were compared in terms accuracy (ACC), sensitivity (SE), specificity (SP), AUC (Area Under the Curve)-ROC (Receiver Operator Characteristic) curve and kappa statistic. RF model scored the highest in terms of ACC (0.91), specificity (0.94), Kappa statistics (0.82) and AUC (0.98). In conclusion, RF model had the best performance in predicting the type of NBP hence can be used as a suitable automated method to classify the type of NBP.

Classification of Partial Discharge in Vehicle-Mounted Cable Termination of High-Speed Electric Multiple Unit: A Machine Learning-Based Approach

This paper presents a machine learning-based approach to identify and separate partial discharge (PD) and two typical pulse interference (PI) signals in the vehicle-mounted cable terminations of high-speed electric multiple units (EMUs). First, a test platform was established to capture PD and two typical PI signals in these terminations. The acquired signals were then processed using the square envelope method to extract feature parameters, such as the rise time proportion, the left–right symmetry, and the upper–lower symmetry. PD signal classification was carried out on these signals, utilizing waveform parameters derived from a hierarchical clustering algorithm. The results validate that the extracted feature components effectively classify and separate PD and two typical PI signals in the vehicle-mounted cable terminations of high-speed EMUs.

Peale's dolphins (Lagenorhynchus australis) are acoustic mergers between dolphins and porpoises

Most dolphin species produce broadband clicks for echolocation (i.e., biosonar pulses), and whistles and burst-pulsed calls for communication purposes. A few dolphin species in the southern hemisphere are reported to only produce clicks of a more narrowband high-frequency (NBHF) type, very similar to the clicks produced by porpoises. Here, we use underwater acoustic recordings of Peale's dolphins (Lagenorhynchus australis) in the Falkland Islands to show that they also can produce broadband clicks and tonal whistle sounds similar to other whistling odontocete species in addition to NBHF clicks. Whistles and broadband clicks co-occurred in seven out of twelve acoustic encounters with Peale's dolphins. The co-occurrence of whistles and broadband signals, which were predominately burst-pulses, produced by Peale's dolphins in this study points to a probable function as communication signals. Furthermore, the measured frequency and time parameters of Peale's dolphin whistles were comparable with whistles recorded from four additional species in the Lagenorhynchus genus in various parts of their ranges. This is the only species of Lagenorhynchus recorded to date that can relax acoustic crypsis in a similar manner as Heaviside's (Cephalorhynchus heavisidii), Commerson's (C. commersonii), and Hector's (C. hectori) dolphins. Our findings make it likely that additional NBHF species have the ability to generate both pulsed signal types and whistles, and further challenges the acoustic classification of NBHF species.

Non-destructive three-dimensional characterization of micronized pulse seeds using X-ray microcomputed tomography

Non-destructive quality evaluation techniques are vital in 3D visualization and quantification of microstructural changes in micronized pulse kernels. The effects of micronization (infrared heating) on pulse microstructure are highly dependent on its treatment efficiency. This study employed X-ray micro-computed tomography (micro-CT) to characterize, visualize, and quantify the microstructural changes non-destructively. Four major pulses, chickpeas, fava beans, lentils, and yellow peas, were subjected to micronization at 180 °C of surface temperature for four different infrared (IR) exposure times (60, 80, 100, and 120 s). All samples were pre-conditioned at 20 % moisture content before the micronization process. Morphometric parameters (pore size, diameter, and pore distribution) were qualitatively measured using the reconstructed 2D and 3D images acquired by the X-ray micro-CT. Physico-chemical parameters, including loss of moisture (%), total porosity (%), volumetric expansion/shrinkage (%), and density (%) were quantified using Micro-CTAn software. The results showed that the porosity is significantly increased (p < 0.05) in all pulse types ranging from 0.60 ± 0.42 % to 12.1 ± 2.68 %, at prolonged IR exposure time. Significant volume expansion ranging from 3.82 %–33.56 % was shown by chickpeas and yellow peas, while fava beans and lentils showed volume shrinkage ranging from 4.26 %–24.31 % after micronization. Furthermore, density was decreased ranging from 0.79 ± 0.25% to 33.49 ± 0.42 % with increased IR time for all pulses except fava beans. The authors found that the microstructural changes in all tested pulses were optimum at 100 s–120 s of exposure time. Results emphasize the higher potential in modifying the microstructure of pulses using micronization processing. Therefore, future studies are suggested on developing predictive models to explore the relationships between microstructural changes and techno-functional properties.

Effect of burst mode modulation ultrashort pulse laser on the laser processing transparent dielectrics

The effect of ultrashort pulse modulation on the formation of a modified zone of a transparent dielectric was investigated. The use of a femtosecond fiber laser in burst mode made it possible to control the energy that enters the processed material and thereby influence the geometry of the modification zone. In the course of the study, various types of pulses were tested—linear, sinusoidal, exponential, etc. It was noted that pulse modulation significantly affects the shape of the modified zone. Energy thresholds have been determined that lead to internal defects in the form of cracks.

Chirped Pulses Meet Quantum Dots: Innovations, Challenges, and Future Perspectives

AbstractShaped laser pulses have been remarkably effective in investigating various aspects of light–matter interactions spanning a broad range of research. Chirped laser pulses exhibiting a time‐varying frequency, or quadratic spectral phase, form a crucial category in the group of shaped laser pulses. This type of pulses have made a ubiquitous presence from spectroscopic applications to developments in high‐power laser technology, and from nanophotonics to quantum optical communication, ever since their introduction. In the case of quantum technologies recently, substantial efforts are being invested toward achieving a truly scalable architecture. Concurrently, it is important to develop methods to produce robust photon sources. In this context, semiconductor quantum dots hold great potential, due to their exceptional photophysical properties and on‐demand operating nature. Concerning the scalability aspect of semiconductor quantum dots, it is advantageous to develop a simple, yet robust method to generate photon states from it. Chirped pulse excitation has been widely demonstrated as a robust and efficient state preparation scheme in quantum dots, thereby boosting its applicability as a stable photon source in a real‐world scenario. Despite the rapid growth and advancements in laser technologies, the generation and control of chirped laser pulses can be demanding. Here, an overview of a selected few approaches is presented to tailor and characterize chirped pulses for the efficient excitation of a quantum dot source. By taking the chirped‐pulse‐induced adiabatic rapid passage process in quantum dot as an example, numerical design examples are presented along with experimental advantages and challenges in each method and conclude with an outlook on future perspectives.

An ultra-low quiescent current power-on reset circuit with DDPG method

An ultra-low quiescent current power-on reset (POR) circuit with double-delay pulse generation (DDPG) method is presented in this paper. The circuit is designed for non-volatile memory (NVM) systems, aiming to ensure reliable initialization and enhance overall efficiency. To address the challenge of inaccurate trigger-point voltage caused by process, voltage, temperature (PVT) and ramp time variations, a novel pulse generation method is proposed. Additionally, the circuit further improves the reliability of pulse duration through the utilization of low-cost current reference generators. Implemented in standard 40 nm CMOS technology, the delay-based POR circuit consumes only 0.24 nA quiescent current and occupies a compact area of 25.6μm×102μm. The simulation results demonstrate a typical pulse duration time of 28μs, with a temperature coefficient (TC) of 101.4 ppm/°C. The high reliability and low overhead of this circuit make it suitable for NVM systems and other fast power-on applications.

A Patient Management System Using an Edge Computing-Based IoT Pulse Oximeter

Edge computing can provide core functions such as data collection and analysis without connecting to a centralized server. The convergence of edge computing and IoT devices has enabled medical institutions to collect patient data in real time, improving the efficiency of short- and long-term patient management. Medical equipment measures a large amount of biosignal data for analyzing diseases and patient health conditions. However, analyzing and monitoring biosignal data using a centralized server or cloud limit the medical institutions’ ability to analyze patients’ conditions in real time, preventing prompt treatment. Therefore, edge computing can enhance the efficiency of patient biosignal data collection and analysis for patient management systems. Analyzing biosignals using edge computing can eliminate the wait time present in cloud computing. Hence, this study aims to develop an IoT pulse oximeter using edge computing for medical institutions and proposes an architecture for providing a real-time monitoring service. The proposed system utilizes five types of raw (IR AC, IR DC, red AC, red DC, AMB), pulse, and SpO2 data measured using IoT pulse oximeters. Edge nodes are installed in every hospital ward to collect, analyze, and monitor patient biosignal data through a wireless network. The collected biosignal data are transmitted to the cloud for managing and monitoring the data of all patients. This system enables medical institutions to collect and analyze raw biosignal data in real time, by which an integrated management system can be established by connecting various types of IoT-based medical equipment.

Dynamics of different pulse types in a single-/dual-wavelength mode-locked fiber laser

Dynamics of different pulse types in a single-/dual-wavelength mode-locked fiber laser