Frequency Research Articles

Enhancing Peer Greeting Skills in Early Childhood Children with ASD Through SST

This study investigates the efficacy of Social Skill Training (SST) in enhancing the social skills of children with autism spectrum disorder (ASD) during kindergarten years. Children with ASD often struggle with social interactions, hindering their integration into preschool environments. Using a quantitative approach with a Single Subject Research (SSR) A-B-A design, this research focused on improving the "peer greeting" skill, specifically through waving. Results indicate significant improvement across study phases, with waving frequency increasing from 3-4 times in baseline-1 to 6-7 times during intervention, and further to 9-10 times in baseline-2. The findings underscore the effectiveness of SST in enhancing social skills among children with ASD, particularly in initiating greetings through waving. This research contributes valuable insights into evidence-based interventions for improving social interactions in children with ASD during their formative years.

Dependence Modelling for Heavy-Tailed Multi-Peril Insurance Losses

The Danish fire loss dataset records commercial fire losses under three insurance coverages: building, contents, and profits. Existing research has primarily focused on the heavy-tail behaviour of the losses but ignored the relationship among different insurance coverages. In this paper, we aim to model the aggregate loss for all three coverages. To study the pairwise dependence of claims from all types of coverage, an independent model, a hierarchical model, and some copula-based models are proposed for the frequency component. Meanwhile, we applied composite distributions to capture the heavy-tailed severity component. It is shown that consideration of dependence for the multi-peril frequencies (i) significantly enhances model goodness-of-fit and (ii) provides more accurate risk measures of the aggregated losses for all types of coverage in total.

Time–Frequency and Spectrum Analyses of All-Solid-State Self-Mode-Locked Burst Pulse Lasers

The theoretical and experimental characteristics of all-solid-state self-mode-locked burst pulse lasers are investigated in this study. The time–frequency and spectrum analyses of the lasers incorporating Fabry–Pérot (F-P) structures are presented, along with the development of the corresponding theoretical model. Self-mode-locked burst pulse lasers are experimentally constructed to reduce intracavity losses using the front and rear end surfaces of the gain media to form F-P structures. When the laser cavity length is 600 mm and the gain media lengths are 5, 6, and 10 mm, each burst pulse produced contains 56, 47, and 28 subpulses, respectively, with the same burst pulse width of 2 ns. The burst pulse train with beam quality M2 = 1.37 and an average output power of 0.23 W is obtained when the gain medium length is 5 mm and the pump power is 4.5 W. The corresponding burst pulse repetition frequency is 0.25 GHz and the subpulse repetition frequency is 13.66 GHz. The time–frequency spectral analyses of the laser signals provide a good representation of laser spectral information that even the currently available highest-resolution spectrometers cannot resolve.

Diode-end-pumped self-Q-switched Tm:YAlO3 laser at 2362 nm

A diode-end-pumped self-Q-switched Tm:YAlO3 laser at 2362 nm based on 3H4→3H5 transition is proposed for the first time according to the references. The max mean output power of 0.41 W with a slope efficiency of 14.1% was obtained under the absorbed pump power of 6.7 W, corresponding pulse width and pulse repetition frequency were 7.82 μs and 45.09 kHz respectively. By analyzing the laser beam spatial distribution, the self-Q-switched Tm:YAlO3 laser at 2362 nm was originated from the time-dependent lens mechanism. The present research provides an approach for generating Q-switched lasers in the 2.3 μm spectral region.

Time-domain diffuse optical imaging technique for monitoring rheumatoid arthritis disease activity: theoretical development and in silico validation

Objective. Effective early treatment—within 3–5 months of disease onset—significantly improves rheumatoid arthritis (RA) prognosis. Nevertheless, 1 in 3 patients experiences treatment failure which takes 3–6 months to detect with current monitoring techniques. The aim of this work is to develop a method for extracting quantitative features from data obtained with time-domain diffuse optical imaging (TD-DOI), and demonstrate their sensitivity to RA disease activity. Approach. 80 virtual phantoms of the proximal interphalangeal joint—obtained from a realistic tissue distribution derived from magnetic resonance imaging—were created to simulate RA-induced alterations in 5 physiological parameters. TD-DOI images were generated using Monte Carlo simulations, and Poisson noise was added to each image. Subsequently, each image was convolved with an instrument response function (IRF) to mimic experimental measurements. Various spatiotemporal features were extracted from the images (i.e. statistical moments, temporal Fourier components), corrected for IRF effects, and correlated with the disease index (DI) of each phantom. Main results. Spatiotemporal Fourier components of TD-DOI images were highly correlated with DI despite the confounding effects of noise and the IRF. Moreover, lower temporal frequency components ( ⩽ 0.4 GHz) demonstrated greater sensitivity to small changes in disease activity than previously published spatial features extracted from the same images. Significance. Spatiotemporal components of TD-DOI images may be more sensitive to small changes in RA disease activity than previously reported DOI features. TD-DOI may enable earlier detection of RA treatment failure, which would reduce the time needed to identify treatment failure and improve patient prognosis.

Strategies and safety simulations for ultrasonic cervical spinal cord neuromodulation

Objective. Focused ultrasound spinal cord neuromodulation has been demonstrated in small animals. However, most of the tested neuromodulatory exposures are similar in intensity and exposure duration to the reported small animal threshold for possible spinal cord damage. All efforts must be made to minimize the risk and assure the safety of potential human studies, while maximizing potential treatment efficacy. This requires an understanding of ultrasound propagation and heat deposition within the human spine. Approach. Combined acoustic and thermal modelling was used to assess the pressure and heat distributions produced by a 500 kHz source focused to the C5/C6 level via two approaches (a) the posterior acoustic window between vertebral posterior arches, and (b) the lateral intervertebral foramen from which the C6 spinal nerve exits. Pulse trains of fifty 0.1 s pulses (pulse repetition frequency: 0.33 Hz, free-field spatial peak pulse-averaged intensity: 10 W cm−2) were simulated for four subjects and for ±10 mm translational and ±10∘ rotational source positioning errors. Main results. Target pressures ranged between 20%–70% of free-field spatial peak pressures with the posterior approach, and 20%–100% with the lateral approach. When the posterior source was optimally positioned, peak spine heating values were below 1 ∘C, but source mispositioning resulted in bone heating up to 4 ∘C. Heating with the lateral approach did not exceed 2 ∘C within the mispositioning range. There were substantial inter-subject differences in target pressures and peak heating values. Target pressure varied three to four-fold between subjects, depending on approach, while peak heating varied approximately two-fold between subjects. This results in a nearly ten-fold range between subjects in the target pressure achieved per degree of maximum heating. Significance. This study highlights the utility of trans-spine ultrasound simulation software and need for precise source-anatomy positioning to assure the subject-specific safety and efficacy of focused ultrasound spinal cord therapies.

Infants' abilities to segment word forms from spectrally degraded speech in the first year of life.

Infants begin to segment word forms from fluent speech-a crucial task in lexical processing-between 4 and 7 months of age. Prior work has established that infants rely on a variety of cues available in the speech signal (i.e., prosodic, statistical, acoustic-segmental, and lexical) to accomplish this task. In two experiments with French-learning 6- and 10-month-olds, we use a psychoacoustic approach to examine if and how degradation of the two fundamental acoustic components extracted from speech by the auditory system, namely, temporal (both frequency and amplitude modulation) and spectral information, impact word form segmentation. Infants were familiarized with passages containing target words, in which frequency modulation (FM) information was replaced with pure tones using a vocoder, while amplitude modulation (AM) was preserved in either 8 or 16 spectral bands. Infants were then tested on their recognition of the target versus novel control words. While the 6-month-olds were unable to segment in either condition, the 10-month-olds succeeded, although only in the 16 spectral band condition. These findings suggest that 6-month-olds need FM temporal cues for speech segmentation while 10-month-olds do not, although they need the AM cues to be presented in enough spectral bands (i.e., 16). This developmental change observed in infants' sensitivity to spectrotemporal cues likely results from an increase in the range of available segmentation procedures, and/or shift from a vowel to a consonant bias in lexical processing between the two ages, as vowels are more affected by our acoustic manipulations. RESEARCH HIGHLIGHTS: Although segmenting speech into word forms is crucial for lexical acquisition, the acoustic information that infants' auditory system extracts to process continuous speech remains unknown. We examined infants' sensitivity to spectrotemporal cues in speech segmentation using vocoded speech, and revealed a developmental change between 6 and 10 months of age. We showed that FM information, that is, the fast temporal modulations of speech, is necessary for 6- but not 10-month-old infants to segment word forms. Moreover, reducing the number of spectral bands impacts 10-month-olds' segmentation abilities, who succeed when 16 bands are preserved, but fail with 8 bands.

Pulsed electric field performance calculator tool based on an in vitro human cardiac model.

Pulsed Field Ablation (PFA) is a novel non-thermal method for cardiac ablation, relying on irreversible electroporation induced by high-energy pulsed electric fields (PEFs) to create localized lesions in the heart atria. A significant challenge in optimizing PFA treatments is determining the lethal electric field threshold (EFT), which governs ablation volume and varies with PEF waveform parameters. However, the proprietary nature of device developer's waveform characteristics and the lack of standardized nonclinical testing methods have left optimal EFTs for cardiac ablation uncertain. To address this gap, we introduced a laboratory protocol employing human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in monolayer format to evaluate the impact of a range of clinically relevant biphasic pulse parameters on lethal EFT and adiabatic heating (AH). Cell death areas were assessed using fluorescent dyes and confocal microscopy, while lethal EFTs were quantified through comparison with electric field numerical simulations. Our study confirmed a strong correlation between cell death in hiPSC-CMs and the number and duration of pulses in each train, with pulse repetition frequency exerting a comparatively weaker influence. Fitting of these results through machine learning algorithms were used to develop an open-source online calculator. By estimating lethal EFT and associated temperature increases for diverse pulse parameter combinations, this tool, once validated, has the potential to significantly reduce reliance on animal models during early-stage device de-risking and performance assessment. This tool also offers a promising avenue for advancing PFA technology for cardiac ablation medical devices to enhance patient outcomes.

CH3NH3PbBr3 as a saturable absorber for infrared passively Q-switched solid-state laser

Perovskite materials are used in the field of lasers and can achieved good results. In this paper, we prepared an organic–inorganic hybridized CH3NH3PbBr3 saturable absorber (SA). Continuous wave (CW) Tm:YAP solid-state lasers with CH3NH3PbBr3-SA successfully obtained pulsed lasing at 1987.5 nm after continuous tuning. In CW mode, the maximum absorbed pump power by the laser was 19.42 W, which corresponds to 0.68 W output power. The central output wavelength of the continuous wave laser was 1989.9 nm. In PQS mode, the output power of laser was 203 mW. Under the condition of maximum repetition frequency of 45 kHz, the narrowest pulse width of the PQS laser were 1.16 μs. Meanwhile, the laser produced a maximum single-pulse energy (4.5 μJ) and a maximum peak power (3.9 W). The beam quality factors (the horizontal/vertical directions) were M2 x = 1.1 and M2 y = 1.39. The CH3NH3PbBr3 was an excellent SA for infrared PQS solid-state lasers, which had a large potential for development applications in the field of lasers.

Criticality and chaos in auditory and vestibular sensing

The auditory and vestibular systems exhibit remarkable sensitivity of detection, responding to deflections on the order of angstroms, even in the presence of biological noise. The auditory system exhibits high temporal acuity and frequency selectivity, allowing us to make sense of the acoustic world around us. As the acoustic signals of interest span many orders of magnitude in both amplitude and frequency, this system relies heavily on nonlinearities and power-law scaling. The vestibular system, which detects ground-borne vibrations and creates the sense of balance, exhibits highly sensitive, broadband detection. It likewise requires high temporal acuity so as to allow us to maintain balance while in motion. The behavior of these sensory systems has been extensively studied in the context of dynamical systems theory, with many empirical phenomena described by critical dynamics. Other phenomena have been explained by systems in the chaotic regime, where weak perturbations drastically impact the future state of the system. Using a Hopf oscillator as a simple numerical model for a sensory element in these systems, we explore the intersection of the two types of dynamical phenomena. We identify the relative tradeoffs between different detection metrics, and propose that, for both types of sensory systems, the instabilities giving rise to chaotic dynamics improve signal detection.

What does visual snow look like? Quantification by matching a simulation.

The primary symptom of visual snow syndrome (VSS) is the unremitting perception of small, flickering dots covering the visual field. VSS is a serious but poorly understood condition that can interfere with daily tasks. Several studies have provided qualitative data about the appearance of visual snow, but methods to quantify the symptom are lacking. Here, we developed a task in which participants with VSS adjusted parameters of simulated visual snow on a computer monitor until the simulation matched their internal visual snow. On each trial, participants (n = 31 with VSS) modified the size, density, update speed, and contrast of the simulation. Participants' settings were highly reliable across trials (intraclass correlation coefficients > 0.89), and they reported that the task was effective at stimulating their visual snow. On average, visual snow was very small (less than 2 arcmin in diameter), updated quickly (mean temporal frequency = 18.2 Hz), had low density (mean snow elements vs. background = 2.87%), and had low contrast (average root mean square contrast = 2.56%). Our task provided a quantitative assessment of visual snow percepts, which may help individuals with VSS communicate their experience to others, facilitate assessment of treatment efficacy, and further our understanding of the trajectory of symptoms, as well as the neural origins of VSS.

High average output power, dual-wavelength synchronously self-mode-locked Ho:LLF laser operating at 2068.5 and 2069.2 nm.

A dual-wavelength synchronously self-mode-locked Ho:LLF laser operating at 2068.5 and 2069.2 nm was demonstrated. The maximum average output power was as high as 2.6 W with a pulse repetition frequency of 3.03 GHz. Meanwhile, the output power ratio of the dual-wavelength lasers can be effectively controlled by varying the incident pump power. To the best of our knowledge, this is the first dual-wavelength synchronously self-mode-locked Ho-doped fluoride solid state laser; moreover, our current experimental results represent the highest average output power from a GHz self-mode-locked oscillator in the 2 µm wave band.

Picosecond Laser Processing of Hierarchical Micro–Nanostructures on Titanium Alloy upon Pre‐ and Postanodization: Morphological, Structural, and Chemical Effects

Recent publications indicate that the order of electrochemical anodization (before or after the laser processing step) plays an important role for the response of bone‐forming osteoblasts—an effect that can be utilized for improving permanent dental or removable bone implants. For exploring these different surface functionalities, multimethod morphological, structural, and chemical characterizations are performed in combination with electrochemical pre‐ and postanodization for two different characteristic microspikes covered by nanometric laser‐induced periodic surface structures on Ti–6Al–4V upon irradiation with near‐infrared ps‐laser pulses (1030 nm wavelength, ≈1 ps pulse duration, 67 and 80 kHz pulse repetition frequency) at two distinct sets of laser fluence and beam scanning parameters. This work involves morphological and topographical investigations by scanning electron microscopy and white light interference microscopy, structural material examinations via X‐ray diffraction, and micro‐Raman spectroscopy, as well as near‐surface chemical analyses by X‐ray photoelectron spectroscopy and hard X‐ray photoelectron spectroscopy. The results allow to qualify the mean laser ablation depth, assess the spike geometry and surface roughness parameters, and provide new detailed insights into the near‐surface oxidation that may affect the different cell growth behavior for pre‐ or postanodized medical implants.

Average dose rate is the primary determinant of lipid peroxidation in liposome membranes exposed to pulsed electron FLASH beam

BackgroundLipid peroxidation, a self-propagating chain reaction that oxydates lipid molecules, contributes to harmful effects of ionizing radiation. A decrease in peroxidation at higher dose rates could play a role in the FLASH sparing effect. PurposeWe explored how lipid peroxidation induced by FLASH (>100 Gy/s) and conventional (CONV, <0.2 Gy/s) radiation depends on lipid concentration and content of polyunsaturated fatty acids (PUFA). Additionally, we investigated the correlation between the lipid peroxidation and the main beam parameters characterizing pulsed electron beams, namely the dose per pulse (DRp) and the average dose rate (DRav). MethodsWe employed phosphatidylcholine (PC) liposomes as a model of biological membranes. Suspensions of liposomes containing different proportions of linoleic acid (LA) were prepared at various concentrations and irradiated at FLASH and CONV dose rates. Additionally, the liposomes were exposed to beams characterized by diverse combinations of DRp and DRav. The extent of lipid peroxidation was assessed by monitoring oxygen consumption (ΔpO2) and measuring the yield of malondialdehyde (MDA), and in certain instances, of lipid peroxides (LOOH). ResultsRegardless of the radiation dose, liposome concentration or LA content, ΔpO2 and the yield of MDA were significantly lower for FLASH than for CONV irradiation. Increase in the proportion of readily oxidizable LA in the lipid had negative effect on the MDA yield but correlated positively with ΔpO2 and LOOH yield. Exposing liposomes to beams operating at different pulse repetition frequencies, while keeping the total dose and DRp constant, resulted in markedly different ΔpO2 and MDA yields. In contrast, DRav was found to exhibit stable correlation with both MDA yield and ΔpO2. ConclusionsIrradiation at FLASH dose rates produces lower yield of lipid peroxidation in PUFA-containing artificial PC membranes than CONV irradiation under all tested conditions. Time-averaged dose rate, in contrast to pulse dose rate, was the critical parameter determining the level of lipid peroxidation induced by pulsed electron beams.

A multifunctional and reconfigurable memristive neuron circuit

AbstractA memristive neuron circuit which is capable of encoding input information via temporal and adaptive frequency methods within the same structure is proposed. Its multifunctionality allows switching between these modes by adjusting circuit capacitors. Furthermore, it is investigated how other parameters like input voltage and resistance influence output properties for different encoding methods. This research contributes to the development of more flexible neuromorphic computing systems.

Optimized Recovery of the Frequency of Repetition of a Satellite Quantum Signal

Optimized Recovery of the Frequency of Repetition of a Satellite Quantum Signal

Effect of Annealing Process on the Morphological, Optical and Electrical Properties of Cu:MnO Films Prepared by PLD Technique

In this study, Nd:YAG laser pulses with a wavelength of 1064 nm, a power of 500 mJ, a pulse width of 9 ns, and a repetition frequency of 6 Hz were used to hit a manganese oxide (MnO) target surface 300 times. Pure MnO and copper Cu-doped MnO (Cu:MnO) with different amounts of Cu (0.03, 0.05, 0.07, and 0.09 wt%) produced by PLD were studied. Cu:MnO thin films were annealed at 473 K, and their morphological, optical, and electrical characteristics were studied. The results of the atomic force microscopic (AFM) investigation of morphological properties showed that Cu dopant impacted the creation of roughness and particle size in MnO2 films. The optical transmission was examined using a UV-Vis spectrophotometer. The highest optical absorption was noted at 0.09 dopant content. The dielectric constants' real (εr) and imaginary (εi) components, as well as the extinction coefficient (k), refractive index (n), and other optical constants, were studied. At an annealing temperature of (473 K), Hall effect studies demonstrate that all produced films exhibit a P-type conductivity.

Performance Evaluation of Spaceborne Bistatic SAR Systems

In this paper, the performances of spaceborne bistatic synthetic aperture radar (SAR) systems are evaluated and compared with those of the conventional monostatic SAR system. Drawing on information on the altitude of satellites and the pulse repetition frequency of the system, the distance between the satellites carrying the transmitter and the receiver is first determined to then obtain the maximum observable width by overlapping the blind ranges. The performances of the bistatic SAR for two satellites at the same altitude moving parallel to each other at the same speed are evaluated, and the results are compared with those obtained from a monostatic SAR system located at left or right end of the baseline. The resolutions, noise equivalent sigma zero, and ambiguities of the bistatic SAR are evaluated based on the windows between blind incident angles of a timing diagram. Subsequently, the most ap-propriate window is determined by comparing the evaluated performances of the bistatic SAR.

Influence of advertisement on consumers’ buying behavior: A case study of FMCG products

The primary objective of the current study is to examine how advertising impacts the consumer behavior of University students (N = 200). This study aims to delve into the influence of advertising on attitudes related to purchasing behavior. A questionnaire was developed to assess the effect of advertising, and the sample data were gathered from college/University students aged between 20 and 30. Specifically, eight fast-moving consumer goods (FMCG) brands, namely Lux, Pears, Dettol, Dove, Head &amp; Shoulders, L'Oreal Paris, Dove and Tresemme, were considered in the analysis. The data collection process involved evaluating the correlations between these brands and their respective advertisements. The analysis encompassed the utilization of mean, standard deviation, frequency, and percentage, which were then presented in tabular form. The findings unveiled that advertisements play a pivotal role in steering preferences and choices, significantly influencing consumer buying behavior. The model employed in this study appeared to have a more pronounced impact on consumers compared to conventional modes of advertising. Additionally, the results indicated that consumers perceive advertisements as a credible source of information in contrast to other opinions, such as those from friends, neighbors, or reference groups. The study demonstrated that advertisements wield a substantial influence across diverse income groups, regardless of the economic bracket. Interestingly, the study found that the costliness of products and the frequency of advertisement repetition did not significantly alter consumer buying behavior. Among the brands considered, DOVE emerged as the most preferred, followed by PEARS. Notably, more consumers were affected by Dove and Tresemme's advertisement than by Head &amp; Shoulders. Due to Head &amp; Shoulder’s competitive pricing, users favor it over other shampoo brands. The flash of advertising on the big screen drew attention to it and had an impact on consumers.

Compact hundred-watt level picosecond laser system based on tapered double cladding fiber-single crystal fiber hybrid amplifier

This paper introduces a compact picosecond laser system using tapered double cladding fiber-single crystal fiber hybrid amplification technology for the first time. By modifying the Ginzburg-Landau equation, we established a simulation model and designed a passive mode-locked picosecond oscillator based on a semiconductor saturable absorber mirror. The oscillator outputs laser with a pulse width of 7.75 ps, a center wavelength of 1030.55 nm, and a spectrum width of 0.58 nm. The seed laser is stretched and amplified by the all-fiber front stage, and then injected into the tapered double cladding fiber-single crystal fiber hybrid amplifier. The laser power is amplified from 820 mw to 103.1 W, obtaining a gain of 21 dB. We used zero-phonon line pumping technology in single crystal fiber amplifier to reduce the thermal effects caused by quantum loss, thereby increasing the length of the crystal and increasing the power loading capacity. We designed a single crystal fiber amplification module using Yb:YAG with 60 mm long, 1 mm diameter and a 1 at.% doping rate for the first time. Finally, a hundred-watt level picosecond laser output with a repetition frequency of 26.33 MHz, an average power of 103.1 W, a pulse width of 244.72 ps, a spectrum width of 1.16 nm, and a beam quality of M2 x = 1.368 and M2 y = 1.511 was obtained. To the best of our knowledge, this is the highest picosecond laser output power for an all-fiber front-stage combined with a single-stage single crystal fiber amplifier.