Wave Amplitude Research Articles

Biomechanical Assessment of Liver Integrity: Prospective Evaluation of Mechanical Versus Acoustic MR Elastography.

Magnetic resonance elastography (MRE) can quantify tissue biomechanics noninvasively, including pathological hepatic states like metabolic dysfunction-associated steatohepatitis. To compare the performance of 2D/3D-MRE using the gravitational (GT) transducer concept with the current commercial acoustic (AC) solution utilizing a 2D-MRE approach. Additionally, quality index markers (QIs) were proposed to identify image pixels with sufficient quality for reliably estimating tissue biomechanics. Prospective. One hundred seventy participants with suspected or confirmed liver disease (median age, 57 years [interquartile range (IQR), 46-65]; 66 females), and 11 healthy volunteers (median age, 31 years [IQR, 27-34]; 5 females). Participants were scanned twice at 1.5 T and 60 Hz vibration frequency: first, using AC-MRE (2D-MRE, spin-echo EPI sequence, 11 seconds breath-hold), and second, using GT-MRE (2D- and 3D-MRE, gradient-echo sequence, 14 seconds breath-hold). Image analysis was performed by four independent radiologists and one biomedical engineer. Additionally, superimposed analytic plane shear waves of known wavelength and attenuation at fixed shear modulus were used to propose pertinent QIs. Spearman's correlation coefficient (r) was applied to assess the correlation between modalities. Interreader reproducibility was evaluated using Bland-Altman bias and reproducibility coefficients. P-values <0.05 were considered statistically significant. Liver stiffness quantified via GT-2D/3D correlated well with AC-2D (r ≥ 0.89 [95% CI: 0.85-0.92]) and histopathological grading (r ≥ 0.84 [95% CI: 0.72-0.91]), demonstrating excellent agreement in Bland-Altman plots and between readers (κ ≥ 0.86 [95% CI: 0.81-0.91]). However, GT-2D showed a bias in overestimating stiffness compared to GT-3D. Proposed QIs enabled the identification of pixels deviating beyond 10% from true stiffness based on a combination of total wave amplitude, temporal sinusoidal nonlinearity, and wave signal-to-noise ratio for GT-3D. GT-MRE represents an alternative to AC-MRE for noninvasive liver tissue characterization. Both GT-2D and 3D approaches correlated strongly with the established commercial approach, offering advanced capabilities in abdominal imaging compared to AC-MRE. 1 TECHNICAL EFFICACY: Stage 2.

Impaired cognitive flexibility in major depressive disorder: Evidences from spatial-temporal ERPs analysis

BackgroundMajor Depressive Disorder (MDD) may exhibit impairments in cognitive flexibility. This study investigated whether the cognitive flexibility deficits in MDD are evident across general stimuli or specific to emotional stimuli, while exploring the underlying neuropsychological mechanism. MethodsA total of 41 MDD patients and 42 healthy controls (HCs) were recruited. Event-related potentials (ERPs) were recorded when participants performed a non-emotional and an emotional task switching paradigm (N-ETSP and ETSP), both of which assessed cognitive flexibility. Microstate and source localization analysis were applied to reflect brain activity among different brain areas during task switching. ResultsIn the N-ETSP, MDD group showed larger P3 difference wave (Pd3) amplitudes and longer P2 difference wave (Pd2) latencies. In the ETSP, MDD group displayed smaller N2 difference wave (Nd2) amplitudes and larger Pd3 amplitudes. The comparison of sLORETA images of emotional switch task and emotional repeat task showed that MDD group had increased activation in the precentral gyrus in microstate2 of the P2 time window and had reduced activation in the middle occipital gyrus in microstate3 of the N2 time window. LimitationsThe cross-sectional design failed to capture dynamic changes in cognitive flexibility in MDD. ConclusionsMDD demonstrated impaired cognitive flexibility respond to both non-emotional and emotional stimuli, with greater impairment for negative emotional stimuli. These deficits are evident in abnormal ERPs component during the early attention stage and the later task preparation stage. Furthermore, abnormal emotional switching cost in MDD appears to be related to early abnormal perceptual control in the parietal-occipital cortex.

Microelectromechanical System-Based Reconfigurable Terahertz Metamaterial for Polarization Filter, Switch, and Logic Modulator Applications.

The terahertz (THz) metamaterials integrated with microelectromechanical systems (MEMS) have led to the realization of dynamic control in amplitude, phase, polarization, and spin angular momentum of the THz wave. In this study, we demonstrate an MEMS-based reconfigurable THz metamaterial (RTM) composed of a split ring resonator (SRR) for real-time modulation of THz wave. By gradually increasing the polarization angle of the incident THz wave, the resonant frequency of SRR switches from 0.74 to 1.16 THz, and the maximum modulation depth is more than 70%. When the MEMS-based RTM is actuated by different DC bias voltages, the polarization-dependent transmission intensity and resonant frequency of the device can be actively tuned. MEMS-based RTM shows logical function characteristics that can be used for logic modulators by performing the driving voltages and polarization states as 2-bit input signals and quantizing the transmission response as "on" and "off" states. The logic gates of "NAND" are at 0.439 THz and "AND" is at 0.732 THz. These results offer potential applications for the proposed MEMS-based RTM in tunable and reconfigurable polarization filters, optical switches, programmable logic modulators, and so on.

Central Actions of Leptin Induce an Atrophic Pattern and Improves Heart Function in Lean Normoleptinemic Rats via PPARβ/δ Activation.

Leptin, acting centrally or peripherally, has complex effects on cardiac remodeling and heart function. We previously reported that central leptin exerts an anti-hypertrophic effect in the heart via cardiac PPARβ/δ activation. Here, we assessed the impact of central leptin administration and PPARβ/δ inhibition on cardiac function. Various cardiac properties, including QRS duration, R wave amplitude, heart rate (HR), ejection fraction (EF), end-diastolic left ventricular mass (EDLVM), end-diastolic volume (EDV), and cardiac output (CO) were analyzed. Central leptin infusion increased cardiac PPARβ/δ protein content and decreased HR, QRS duration, and R wave amplitude. These changes induced by central leptin suggested a decrease in the ventricular wall growth, which was confirmed by MRI. In fact, the EDLVM was reduced by central leptin while increased in rats co-treated with leptin and GSK0660, a selective antagonist of PPARβ/δ activity. In summary, central leptin plays a dual role in cardiac health, potentially leading to ventricular atrophy and improving heart function when PPARβ/δ signaling is intact. The protective effects of leptin are lost by PPARβ/δ inhibition, underscoring the importance of this pathway. These findings highlight the therapeutic potential of targeting leptin and PPARβ/δ pathways to combat cardiac alterations and heart failure, particularly in the context of obesity.

Defect Solutions of the Nonreciprocal Cahn-Hilliard Model: Spirals and Targets.

We study the defect solutions of the nonreciprocal Cahn-Hilliard model. We find two kinds of defects, spirals with unit magnitude topological charge, and topologically neutral targets. These defects generate radially outward traveling waves and thus break the parity and time-reversal symmetry. For a given strength of nonreciprocity, spirals and targets with unique asymptotic wave number and amplitude are selected. We use large-scale simulations to show that at low nonreciprocity α, disordered states evolve into quasistationary spiral networks. With increasing α, we observe networks composed primarily of targets. Beyond a critical threshold α_{c}, a disorder-order transition from defect networks to traveling waves emerges. The transition is marked by a sharp rise in the global polar order.

Cloud-Edge Motion by a Ducted Gravity Wave

Abstract The reflection of a wave at a fluid interface is fundamental to the atmospheric wave duct. As latent heating distinguishes the buoyancy response between cloudy and clear air, cloud edges can serve as a ducting interface for gravity waves. However, advection of the thermodynamic conditions by the ducted wave itself can cause evaporation or condensation, where the motion of cloud edges results from shrinking or enlarging regions of saturated air. For an idealized ducted-wave mode trapped by a cloud layer, a linear Boussinesq analysis shows that its vertical motions produce a sinusoidal corrugation of the cloud edge that travels with the wave. When thermodynamic conditions are continuously varying, the cloud edge propagates as the moving onset of phase change, and not as a material interface. Using this Boussinesq solution to initialize the full-physics CM1 model, the simulation confirms the amplitude and speed of the cloud-edge wave. In a comparison of simulations for domains of decreasing height, a convergence to the Boussinesq ducted wave can be quantitatively established. This demonstration suggests a theory-based convergence benchmark for the motion of a cloud edge by phase change.

Revolutionizing bioconvection: Artificial intelligence-powered nano-encapsulation with oxytactic microorganisms

Using incompressible smoothed particle hydrodynamics (ISPH), this study examines the bioconvection flow of oxytactic microorganisms in a porous annulus populated by nano-encapsulated phase change material (NEPCM). Artificial neural network (ANN) is joined with the ISPH method to accurately predict the values of average Nu‾. Between the outside hexagonal-shaped domain and the embedded wavy cylinder, a new annulus is produced. The ranges of the pertinent parameters are wave amplitude of an embedded cylinder A=0.1−0.5, Hartmann number Ha=0−80, a radius of the cylinder Rcyld=0.05−0.5, Darcy number Da=10−2−10−5, undulation number Kund=2−32, bioconvection Rayleigh number Rab=1−1000, Rayleigh number Ra=103−106, and Lewis number Le=1−20. The regulated geometric characteristics of an embedded wavy cylinder, such as wavy amplitude, cylinder radius, and undulation numbers, have been found to contribute significantly to widening the cooling region and minimizing the oxytactic microorganisms. Hence, the embedded wavy cylinder can be applied for various thermal uses including cooling devices and heat exchangers. The average Nu‾ is enhanced under an increment in the geometric parameters of the embedded cylinder. Increasing Rayleigh/bioconvection Rayleigh numbers enhances the buoyancy forces that accelerate the velocity field.

MicroRNA-based engineered mesenchymal stem cell extracellular vesicles to treat visual deficits after blast-induced trauma

Our previous studies have shown the benefit of intravitreal injection of a mesenchymal stem cell (MSC)- derived secretome to treat visual deficits in a mild traumatic brain injury (mTBI) mouse model. In this study, we have addressed whether MSC-derived extracellular vesicles (EV) overexpressing miR424, which particularly targets neuroinflammation, show similar benefits in the mTBI model. Adult C57BL/6 mice were subjected to a 50-psi air pulse on the left side, overlying the forebrain, resulting in mTBI. Sham-blast mice were controls. Within an hour of blast injury, 3 μl (∼7.5 × 108 particles) of miR424-EVs, native-EVs, or saline was delivered intravitreally. One month later, retinal morphology was observed through optical coherence tomography (OCT); visual function was assessed using optokinetic nystagmus (OKN) and electroretinogram (ERG), followed by immunohistological analysis. A separate study in adult mice tested the dose-response of EVs for safety. Blast injury mice with saline showed decreased visual acuity compared with the sham group (0.30 ± 0.03 vs. 0.39 ± 0.01 c/d, p < 0.02), improved with miR424-EVs (0.39 ± 0.02 c/d, p < 0.01) but not native-EVs (0.33 ± 0.04 c/d, p > 0.05). Contrast sensitivity thresholds of blast mice receiving saline increased compared with the sham group (85.3 ± 5.9 vs. 19.9 ± 4.8, %, p < 0.001), rescued by miR424-EVs (23.6 ± 7.3 %, p < 0.001) and native-EVs (45.6 ± 10.7 %, p < 0.01). Blast injury decreased “b” wave amplitude compared to sham mice (94.6 ± 24.0 vs. 279.2 ± 25.3 μV, p < 0.001), improved with miR424-EVs (173.0 ± 27.2 μV, p < 0.03) and native-EVs (230.2 ± 37.2 μV, p < 0.01) with a similar decrease in a-wave amplitude in blast mice improved with both miR424-EVs and native-EVs. Immunohistology showed increased GFAP and IBA1 in blast mice with saline compared with sham (GFAP: 11.9 ± 1.49 vs. 9.1 ± 0.8, mean intensity/100,000 μm2 area, p < 0.03; IBA1: 36.08 ± 4.3 vs. 24.0 ± 1.54, mean intensity/100,000 μm2 area, p < 0.01), with no changes with native-EVs (GFAP: 12.6 ± 0.79, p > 0.05; IBA1: 32.8 ± 2.9, p > 0.05), and miR424-EV (GFAP: 13.14 ± 0.76, p > 0.05; IBA1: 31.4 ± 2.7, p > 0.05). Both native-EVs and miR424-EVs exhibited vitreous aggregation, as evidenced by particulates in the vitreous by OCT, and increased vascular structures, as evidenced by αSMA and CD31 immunostainings. The number of capillary lumens in the ganglion cell layer increased with increased particles in the eye, with native EVs showing the worst effects. In conclusion, our study highlights the promise of EV-based therapies for treating visual dysfunction caused by mTBI, with miR424-EVs showing particularly strong neuroprotective benefits. Both miR424-EVs and native-EVs provided similar protection, but issues with EV aggregation and astrogliosis or microglial/macrophage activation at the current dosage call for improved delivery methods and dosage adjustments. Future research should investigate the mechanisms behind EVs' effects and optimize miR424 delivery strategies to enhance therapeutic outcomes and reduce complications.

Effect of Diurnal Light Conditions on Electroretinogram Responses to Red and Blue Flickering Light.

Bright light impacts the human circadian system such that exposure to bright light at night can suppress melatonin secretion, and exposure to bright light in the morning prevents light-induced melatonin suppression at night. The preventive effect of morning light may attenuate the prior history of light sensitivity of intrinsically photosensitive retinal ganglion cells (ipRGCs) that regulate the circadian system. In this study, we evaluated electroretinogram (ERG) responses to red and blue flickering lights following dim and bright daylight conditions. Eleven healthy females underwent ERG measurements during exposure to 33Hz flickering red or blue light under dim and bright daytime conditions. We averaged ERG waves for 50 flickering light pulses of the trigger signal data. We obtained the amplitude of the signal-averaged ERG by calculating the difference between the waves' peaks and bottoms. Although there was no significant dim and bright light difference in the amplitude of ERG waves, the ERG amplitude to flickering blue light under the bright light condition was significantly lower than to flickering blue light under the dim light condition. In this study, blue light stimulated mainly ipRGCs and S-cones. Since S-cones may contribute minimally to the light-adapted 33Hz flicker ERG results, our findings suggest that bright light during the daytime attenuates the sensitivity of human ipRGCs.

Comparative evaluation of floating OWC and BBDB wave energy converters by regular and irregular waves using numerical approach

ABSTRACT Point absorber wave energy converters (WECs) need to be predicted in order to estimate their durability in high sea states. Although little is known about hydrodynamics and there are few data available. Models of the wave conditions have been developed at the laboratory size using smooth particle hydrodynamics. To investigate how focused waves interact with a point absorber WEC, fixed OWC and BBDB type WEC are coupled. A validation research is evaluated by taking into account the wave amplitude and frequency. The hydrodynamic force and the motion response of the point absorber WEC have been measured throughout time. According to the numerical results, the hybrid configuration with the fixed OWC and BBDB has a significant impact on the motion response and hydrodynamic force. It is demonstrated that the position of hybrid OWCs affects the hydrodynamic force and intense motion response significantly.

Comprehensive design of all-optical logic devices utilizing polarization holography

Polarization holography has emerged as a promising method for manipulating the amplitude, phase, and polarization states of light waves. This study proposes what we believe to be a novel design method for various all-optical logic devices, including a complete set of all-optical Boolean logic gates and a polarization-controlled 1 × 4 optical switch, utilizing polarization holography. Through the angle multiplexing technique, specially designed polarization holograms are recorded in polarization-sensitive material, transforming it into all-optical Boolean logic gates and a polarization-controlled 1 × 4 optical switch. The all-optical logic devices developed in this work function as passive diffractive optical elements, enabled by a single piece of polarization-sensitive material, eliminating the need for additional circuit control. This approach offers the advantages of a simple structure, low cost, and instantaneous response. We contend that this advancement will facilitate the expansion of the application domains of polarization holography, particularly enhancing the capabilities of all-optical information processing.

Effect of sawtooth wave distribution plenum with linearly increasing amplitude on the performance of battery thermal management system

Battery heat generation that occurs during battery charging and discharging can lead to excessive and non-uniform battery temperature in the battery pack. As a result, the battery is more vulnerable to rapid degradation and short cycle life. Effective heat dissipation methods therefore become crucial. In the present study, sawtooth waves with linearly increasing wave amplitude and an inlet notch on the distribution plenum (DP) have been introduced in a typical Z-type battery thermal management system (BTMS) to maximise the cooling effectiveness of the System. Numerical analysis is carried out to investigate the effect of various geometric parameters such as saw tooth wave position, saw tooth wave amplitude, saw tooth wave base width, inlet notch width, and inlet notch height on the performance of BTMS. Velocity contours, streamlines, temperature contours, and maximum battery temperature plots are used to discuss the effects of various factors on the operation of a BTMS. Compared with the typical Z-type BTMS, the modified enclosure design reduced the maximum average battery temperature ( T max ) and maximum temperature differential within the battery pack ( Δ T max ) by 5.11 and 9.01 K respectively, which are 1.56% and 94.90% less than the typical Z-type BTMS respectively.

Uncovering the influence of mechanical properties on wave formation during high-velocity impact welding by numerical simulation

The formation of wavy interface is one of the distinctive features of high-velocity impact welding. It is known that the geometric parameters of waves (amplitude a and length λ) depend not only on the impact conditions, but also on the mechanical properties of the materials being welded. However, until now, the impact of mechanical properties on the formation of waves has only been explored in a limited number of studies. To address this issue, in this paper, we use extensively a numerical simulation. First, we demonstrate that the numerical model, in conjunction with the smooth particle hydrodynamics (SPH) solver, effectively replicates the outcomes of a carefully controlled high-velocity impact welding experiment. Secondly, based on the validated model, we conducted a systematic study of the influence of strength on the wave formation process. Using numerical simulations with Johnson-Cook and ideal elastic-plastic strength models, we show that various characteristics of strength have a profound influence on the wave formation process. Furthermore, it is crucial to consider not only the yield strength of a material, but also factors such as strain and strain-rate hardening, along with thermal softening, to fully understand the wave formation during high-velocity impact welding.

Effect of temperature on the wave breaking amplitude of nonlinear relativistic strong plasma waves

Effect of temperature on the wave breaking amplitude of nonlinear relativistic strong plasma waves

Proportional relations between the wave number and amplitude of spiral waves near Neimark-Sacker bifurcations

The spatiotemporal distribution patterns of interacting populations are broadly accepted as a pivotal factor in sustaining species diversity. Spiral waves represent common spatiotemporal patterns observed in ecosystems and biological systems, encompassing both continuous-time and discrete-time systems. The study of the dynamics and regulation of spiral waves in continuous-time systems, often observed in the vicinity of Hopf bifurcations, has been comprehensively examined. However, the dynamical characteristics and rules governing spiral waves near Hopf bifurcations in discrete-time systems, also named Neimark-Sacker bifurcations, are still not fully understood. Here, we investigate spiral waves in a discrete-time predator-pest model caused by a Neimark-Sacker bifurcation. Our results suggest a linear relationship between the amplitude and wave number of spiral waves near the Neimark-Sacker bifurcation. At last, we propose a model that can describe the behaviors of spiral waves in discrete-time systems near Neimark-Sacker bifurcations. Our findings illuminate the process of pattern formation in discrete-time systems, offering potential insights for forecasting and managing pest distribution.

Study on the internal waves induced by a submerged body moving in a continuously stratified fluid

This paper studies the characteristics of internal waves induced by the motion of a submerged body through a combination of experimental and numerical methods. First, by deploying an array of conductivity probes in an experiment, the temporal evolution of the internal wave at the plane of the conductivity probe array is obtained and compared with numerical simulation results based on the Navier–Stokes equations, thereby validating the accuracy of the Computational Fluid Dynamics (CFD) model. Subsequently, utilizing CFD calculations, further exploration is conducted on the spatiotemporal distribution characteristics of the internal wave, encompassing its generation and evolution, velocity field distribution, wake angle, and wave profile features. Finally, the variation of the internal wave with the Froude number (Fr) is investigated, revealing that it varies apparently with Fr, including the wave component, wave mode, wake length, wake angle, wave amplitude, and so on. It is found that when Fr is large, the internal wave converges toward the centerline behind the body, until forming a line. The wave magnitude changes with Fr in four stages, i.e., increasing with Fr from zero in the first stage, reaching a peak and decreasing thereafter in the second stage, then changing little in the third stage, and finally increasing approximately linearly in the fourth stage.

Detection of a low-frequency ion instability in a magnetic nozzle

Abstract A low-frequency ion instability, with frequency f I between the ion gyrofrequency and the lower hybrid frequency f c , i &lt; f I ≪ f LH , is detected in an argon plasma expanding in a magnetic nozzle for magnetic fields between 240 &lt; B z , max &lt; 700 G. The frequency of the instability exhibits a linear dependence with magnetic field strength, and the wave amplitude has a radial maximum that would match the location of a conical density structure, i.e. high-density cones. For all of the magnetic field cases analysed, the high-frequency spectra showed upper and lower sidebands centred around the driving frequency and at a separation equal to the instability frequency, 27.12 MHz ± f I kHz. Measurements of the perpendicular wavenumber would satisfy, for certain magnetic field strengths, the dispersion relation of both an electrostatic ion cyclotron wave (ICW) and of an ion acoustic wave. It is hypothesised that the observed low-frequency wave could be an acoustic-like instability propagating perpendicular to the magnetic field, which develops as an ICW at some magnetic field strengths. From the data collected, it is suggested that the high-frequency sidebands may be caused by modulation of the low-frequency wave.

Comparative study of two-phase flow approaches for modeling conjugate heat transfer in a three-dimensional wavy microchannel-heat sink with CuO-water nanofluid

This study aims to numerically investigate the conjugate heat transfer (CHT) and the changes in the hydraulic and thermal terms of laminar flow (300 ≤ Re ≤ 800) in a 3-D wavy microchannel heat sink (MCHS). The obtained results from different nanofluid flow simulated models will be compared. The numerical simulation approaches used include single-phase, mixture, Eulerian, DPM, and DDPM. The effect of adding 1%, 3%, and 6% concentration of CuO nanoparticles (100 nm) in deionized water as the base fluid is examined on various parameters such as local and axial temperature, heat transfer convective coefficient, friction factor, Nusselt number (Nu), velocity distribution, and thermal and hydraulic boundary layer parameters. The substrate surface, due to its larger area surface and the amplitude of the sinusoidal wave, has a greater impact on the nanofluid flow as a channel bottom conjugate surface compared to others. The results obtained from the different models show close agreement with each other for various cases. For example, at Re = 304, the average Nu and friction factor for pure water are approximately 10.43 and 0.0260, respectively. For water with 0.01 concentration of CuO nanoparticles, Nu is found to be in the range of 10.43–10.78, and the friction factor ranges from 0.260 to 0.290, depending on the approach used for simulation. This shows a 2% increase in Nusselt number compared to a 0.05% increase in the friction factor. Moreover, these values increase by approximately 5.7% and 11.3% on average with an increase in CuO nanoparticle concentration to 0.06. Additionally, the DPM and DDPM models show a 15% difference in the scattering of CuO nanoparticles compared to the Eulerian-Eulerian models. The single-phase model presented in this study yields similar results to the multiphase approaches. Furthermore, the PEC parameter increases by about 1.9% with the addition of CuO nanoparticles at a concentration of 0.06.

Monsoonal MCS Initiation, Rainfall, and Diurnal Gravity Waves over the Bay of Bengal: Observation and a Linear Model

Abstract Previous observational studies have indicated that mesoscale convective systems (MCSs) contribute the majority of precipitation over the Bay of Bengal (BoB) during the summer monsoon season, yet their initiation and propagation remain incompletely understood. To fill this knowledge gap, we conducted a comprehensive study using a combination of 20-yr satellite observations, MCS tracking, reanalysis data, and a theoretical linear model. Satellite observations reveal clear diurnal propagation signals of MCS initiation frequency and rainfall from the west coast of the BoB toward the central BoB, with the MCS rainfall propagating slightly slower than the MCS initiation frequency. Global reanalysis data indicate a strong association between the offshore-propagating MCS initiation frequency/rainfall and diurnal low-level wind perturbations, implying the potential role of gravity waves. To verify the hypothesis, we developed a 2D linear model that can be driven by realistic meteorological fields from reanalysis. The linear model realistically reproduces the characteristics of offshore-propagating diurnal wind perturbations. The wind perturbations, as well as the offshore propagation signals of MCS initiation frequency and rainfall, are associated with diurnal gravity waves emitted from the coastal regions, which in turn are caused by the diurnal land–sea thermal contrast. The ambient wind speed and vertical wind shear play crucial roles in modulating the timing, propagation, and amplitude of diurnal gravity waves. Using the linear model and satellite observations, we further show that the stronger monsoonal flows lead to faster offshore propagation of diurnal gravity waves, which subsequently control the offshore propagation signals of MCS initiation and rainfall. Significance Statement Rainfall over the Bay of Bengal (BoB) is primarily contributed by large and organized rainfall systems in the summer monsoon season. During this season, these systems are commonly observed over the east coast of India around midnight, the western BoB in the morning, and the central BoB in the afternoon. This eastward rainfall propagation is confirmed by observations, reanalysis data, and a theoretical model to have a strong association with atmospheric diurnal gravity waves. These waves are caused by land–sea thermal contrast and can trigger rainfall systems over the offshore regions. We also found that the diurnal gravity waves, as well as their triggered rainfall systems, can be greatly modulated by the large-scale monsoonal flows. All the above findings improve our understanding of diurnal rainfall cycle over the BoB and may contribute to the future improvement of rainfall forecast over the region.

Measuring of the surface acoustic wave amplitude in the X-112° Y-cut of a LiTaO3 crystal using X-ray diffraction at the laboratory X-ray source

The SAW excitation and propagation on the X-112° Y-cut of a LiTaO3 crystal were studied using a triple-axis X-ray diffractometer with a laboratory X-ray source. Simulation of X-ray rocking curves with the Takagi equation system enabled the determination of surface acoustic wave amplitudes on the crystal surface. The SAW excitation process in the frequency range of an acoustoelectronic device, determined by the excitation band or interdigital transducer structure, was studied.