Decrease In Amplitude Research Articles

Long-term results of treatment of amblyopia in children with impaired fixation mechanism using biofeedback

Purpose: to evaluate the long-term results (1 year) of a new method of treating amblyopia in children with unstable central and eccentric fixation using microperimetric biofeedback, as well as to develop a protocol for patients monitoring after treatment and clear criteria for prescribing repeated courses of treatment using microperimetric biofeedback.Material and methods. The study included 21 patients (21 eyes) aged from 5 to 15 years (ave 8.28 ± 3.08) who were able to perform training sessions on the MP-3 microperimeter (MP, Nidek, Japan). Treatment was carried out on the MP using visual (flickering checkerboard pattern) and sound (sound signal) biofeedback: 10–15 sessions, 10–12 minutes each. All patients were examined before treatment, immediately and 1, 3, 6 and 12 months after the treatment. Dynamic observation of patients and prescription of repeated courses of treatment were carried out in accordance with the developed protocol.Results. After 1 course of treatment, a significant increase in best-corrected visual acuity (BCVA) was detected in 90.4 % of patients, as well as an improvement in all fixation parameters: a significant increase in density by 2° and 4°, a decrease in amplitude by ≈ 50 %; a tendency to increase the functional parameters of the retina in the macular area. During follow-up (1 year), 13 patients (1 patient with central fixation and 12 patients with eccentric fixation) underwent additional courses of biofeedback therapy in accordance with the developed protocol. In 4 patients with eccentric fixation, mainly peripheral, despite improvement in fixation parameters, no additional positive dynamics in visual acuity were noted after a repeated course of biofeedback therapy. In 8 patients, after a repeated course of treatment of amblyopia using biofeedback therapy, positive dynamics were noted, namely: an increase in density and a decrease in the amplitude of fixation, and an increase in BCVA.Conclusion. The effectiveness and safety of a previously developed method of treating amblyopia with impaired fixation mechanism using biofeedback therapy has been demonstrated. A protocol for dynamic monitoring of patients with amblyopia after biofeedback therapy and criteria for prescribing additional courses of training sessions have been developed.

Numerical Analysis of Enhanced Forced Convection in Perforated Surface Wavy Plate-Fin Core

Abstract Steady, periodically fully developed forced convection through three-dimensional perforated sinusoidal wavy-fin cores with uniform wall temperature is computationally investigated. Constant property air flow (Pr ≈ 0.71) with a Reynolds number range of 50 – 4000 covering both laminar and turbulent regimes is considered. The computational solutions, validated with in-house experimental data for continuous and perforated wavy-fin coupons, highlight the effects of perforation locations (characterized by phase angle β), fin porosity, inter-fin spacing, and corrugation amplitude on the thermal-hydraulic performance of the fins. The local temperature, velocity, and pressure variations, and the corresponding local heat transfer coefficient and friction drag (or the Fanning friction factor f and Colburn factor j) are reported. Fluid flows from the adjacent channels through wavy-surface perforations induce secondary flow and interrupt the boundary layer leading to an increase in f and j in both laminar and turbulent regimes. Decrease in corrugation amplitude and inter-fin spacing leads to the suppression of recirculation zones, whereas higher porosity yields increased f and j. Perforated fins nevertheless require less surface area to fulfill a specified heat load condition with a fixed pressure drop as compared to the continuous wavy fins. Furthermore, the perforation location has a noticeable effect on the local heat transfer and flow dynamics and, except for Re <∼200, wavy fins with perforations at relatively higher phase angle β perform better.

Negative Emotion Differentiation Promotes Cognitive Reappraisal: Evidence From Electroencephalogram Oscillations and Phase-Amplitude Coupling.

Cognitive reappraisal, an effective emotion regulation strategy, is influenced by various individual factors. Although previous studies have established a link between negative emotion differentiation (NED) and cognitive reappraisal, the underlying neural mechanisms remain largely unknown. Using electroencephalography, this study investigates the influence and neural basis of NED in cognitive reappraisal by integrating aspects of event-related potentials, neural oscillation rhythms, and cross-frequency coupling. The findings revealed that individuals with high NED demonstrated a significant decrease in parietal late positive potential amplitudes during cognitive reappraisal, suggesting enhanced cognitive reappraisal abilities. Moreover, high NED individuals displayed increased γ synchronization, parietal α-γ coupling, and frontal θ-γ coupling when reappraising negative emotions than those with low emotion differentiation ability. Machine learning analysis of these neural indicators highlighted the superior classification and predictive accuracy of multimodal indicators for NED as opposed to unimodal indicators. Overall, this multimodal evidence provides a comprehensive interpretation of the neurophysiological mechanisms through which NED influences cognitive reappraisal and provides preliminary empirical support for personalized cognitive reappraisal interventions to alleviate emotional problems.

Numerical Simulation on Flow and Heat Transfer Characteristics of a Single-loop Oscillating Heat Pipe with Variable Pipe Diameter Ratios

A three-dimensional numerical model, employing the Volume of Fluid (VOF) method, was developed for a single-loop oscillating heat pipe (OHP) with variable diameters. The investigation explored the impact of varying pipe diameter ratios on flow and heat transfer characteristics at different operational stages under a 40W heat power. The results reveal that the diameter ratio significantly affects the spatial arrangement of the evaporation, adiabatic, and condensation sections in the OHP. In the initial stage, the condensation section displays 15 liquid slugs when the diameter ratio is 1, but this number decreases to fewer than 10 in the same area when the diameter ratio exceeds 1. Comparative to a straight-pipe OHP, configurations with varying diameter ratios exhibit a marginal reduction in the average fluid velocity during the circulation of the working fluid inside the pipe, with the most pronounced velocity decrease occurring at a diameter ratio of 0.8. As the diameter ratio increases to 1.25 and 1.5, the turbulent disturbances in the region where the working fluid flows from the adiabatic section to the evaporation or condensation section intensify, facilitating the temperature exchange within the OHP. During stable operation of the OHP, the frequency of temperature oscillations increases with an increasing diameter ratio, while the amplitude decreases. Among all the cases, the OHP with a diameter ratio of 1.25 has the optimal heat resistance, 1.50K/W. The heat transfer performance of the OHP with a pipe diameter ratio of 0.8 deteriorated, and the thermal resistance increased by 27.6% compared with the straight-pipe OHP.

Detection of Defects in Polyethylene and Polyamide Flat Panels Using Airborne Ultrasound-Traditional and Machine Learning Approach

This paper presents the use of noncontact ultrasound for the nondestructive detection of defects in two plastic plates made of polyamide (PA6) and polyethylene (PE). The aim of the study was to: (1) assess the presence of defects as well as their size, type, and orientation based on the amplitudes of Lamb ultrasonic waves measured in plates made of polyamide (PA6) and polyethylene (PE) due to their homogeneous internal structure, which mainly determined the selection of such model materials for testing; and (2) verify the possibilities of building automatic quality control and defect detection systems based on ML based on the results of the above-mentioned studies within the Industry 4.0/5.0 paradigm. Tests were conducted on plates with generated synthetic defects resembling defects found in real materials such as delamination and cracking at the edge of the plate and a crack (discontinuity) in the center of the plate. Defect sizes ranged from 1 mm to 15 mm. Probes at 30 kHz were used to excite Lamb waves in the slab material. This method is sensitive to the slightest changes in material integrity. A significant decrease in signal amplitude was observed, even for defects of a few millimeters in length. In addition to traditional methods, machine learning (ML) was used for the analysis, allowing an initial assessment of the method’s potential for building cyber-physical systems and digital twins. By training ML models on ultrasonic data, algorithms can distinguish subtle differences between signals reflected from normal and defective areas of the material. Defect types such as voids, cracks, or weak bonds often produce distinct acoustic signatures, which ML models can learn to recognize with high accuracy. Using techniques like feature extraction, ML can process these high-dimensional ultrasonic datasets, identifying patterns that human inspectors might overlook. Furthermore, ML models are adaptable, allowing the same trained algorithms to work on various material batches or panel types with minimal retraining. This combination of automation and precision significantly enhances the reliability and efficiency of quality control in industrial manufacturing settings. The achieved accuracy results, 0.9431 in classification and 0.9721 in prediction, are comparable to or better than the AI-based quality control results in other noninvasive methods of flat surface defect detection, and in the presented ultrasonic method, they are the first described in this way. This approach demonstrates the novelty and contribution of artificial intelligence (AI) methods and tools, significantly extending and automating existing applications of traditional methods. The susceptibility to augmentation by AI/ML may represent an important new property of traditional methods crucial to assessing their suitability for future Industry 4.0/5.0 applications.

Sleep deprivation impairs spatial cognitive processing and Alters brain connectivity in table tennis athletes

Spatial cognitive ability is critical for table tennis athletes to achieve excellent competitive performance, and sleep may be an important factor influencing this ability. This study investigated the impact of 36h sleep deprivation on the spatial cognitive processing of 20 s-level table tennis athletes, using event-related potentials and functional connectivity analysis to assess changes in cognitive resource allocation and inter-regional brain coordination before and after sleep deprivation. The results showed that sleep deprivation significantly prolonged reaction time and led to a decrease in P3 amplitude, reflecting a reduction in participants’ attentional resource allocation and cognitive processing capacity. Functional connectivity analysis further revealed that β frequency band functional connectivity between the frontal and occipital regions significantly decreased after sleep deprivation, indicating reduced brain efficiency in processing spatial information. After 36 h of SD, the spatial cognitive ability of table tennis athletes was impaired. SD not only led to a reduction in the allocation of attentional resources and cognitive processing capabilities in these athletes, but also weakened functional connectivity between the frontal and occipital lobes of the brain.

Motor inhibition during voluntary gait initiation in young and older adults

Based on a novel approach, this study explores feasibility and relevance of an inhibition task for studying age-related differences in motor inhibition during gait initiation. When presented with a go-signal, young adults (YA, n = 24) and older adults (OA, n = 55) were required to promptly initiate gait. Participants completed 3 blocks of 12 gait trials. Each block contained 3 stop trials in which the go-signal was followed by a stop-signal that required the person to block gait initiation and remain standing. Stop-signals were presented randomly and with different delays. Data analyses focused on changes in the centre of pressure (COP) and success of motor inhibition. Compared to go-trials, stop trials resulted in a marked decrease of timing and amplitude of COP displacement. Overall success rate of motor inhibition was low (29% in YA vs. 19% in OA) and decreased with increasing COP displacement. Inhibitory success was associated with two strategies: a pro-active cautious COP displacement; and the inhibition of further COP displacement after a stop-signal. Results demonstrate age-related differences in adaptive behavior as well as boundaries beyond which neither old nor young persons were successful. This study yields important insights into motor inhibition during gait and essential input nto further studies.

Time-dependent phenotypical changes of microglia drive alterations in hippocampal synaptic transmission in acute slices.

It is widely acknowledged that microglia actively regulate synaptic function in the brain. Remarkably, much of our understanding regarding the role of microglia in synaptic regulation is derived from studies in acute brain slices. However, it is still uncertain to what extent the preparation and maintenance of acute slices can influence microglial function and whether microglial changes may affect synaptic transmission. In this study, we examined the impact of acute slice resting time on hippocampal CA1 microglia, by assessing morphological and functional parameters at two distinct time intervals. We report that after 4 h from slicing microglia undergo morphological, functional, and transcriptional changes, including a decrease in the number of branches and in their movement speed. Furthermore, microglia acquire a reactive phenotype, characterized by increased amplitude of outward rectifying K+ currents, increased expression of the pro-inflammatory cytokine Tnfα and altered expression of the microglial receptors Cx3cr1 and P2y12r. We also examined time-dependent changes of excitatory synaptic transmission in CA1 pyramidal neurons from acute hippocampal slices, reporting time-dependent decrease in both amplitude and frequency of postsynaptic currents (sEPSCs), along with a decrease in spine density. Noticeably, sEPSCs amplitude decrease was absent in slices prepared from PLX5622 microglia-depleted mice, suggesting that this time-dependent effect on synaptic transmission is microglia-dependent. Our findings highlight possible causal relation between microglia phenotypic changes in the hours following slice preparation and concomitant synaptic changes, pointing to the mechanisms of acute synaptic modulation, whose understanding is crucial for unraveling microglia-neurons interplay in nature. Furthermore, they emphasize the potential issues associated with experimental time windows in ex vivo samples.

Investigation of traps in halide vapor-phase epitaxy-grown β-Ga2O3 epilayers/n+-Ga2O3 using deep-level transient spectroscopy

Abstract A detailed investigation of deep traps in halide vapor-phase epitaxy (HVPE)-grown β-Ga2O3 epilayers has been done by performing deep-level transient spectroscopy (DLTS) from 200 K to 500 K on Pt/β-Ga2O3 and Ni/β-Ga2O3 Schottky diodes. Similar results were obtained with a fill pulse width of 100 ms irrespective of the different Schottky metal contacts and epilayers. Two electron traps at E2 (E C–E T = 0.65 eV) and E3 (E C–E T = 0.68–0.70 eV) with effective capture cross-sections of 4.10 × 10−14 cm2 and 5.75 × 10−15 cm2 above 300 K were observed. Below 300 K, a deep trap with a negative DLTS signal peak was also observed at E1 (E C–E T = 0.34–0.35 eV) with a very low capture cross-section of 3.28 × 10−17 cm2. For a short pulse width of 100 μs, only two electron traps, E2 and E3, at energies of 0.72 eV and 0.73 eV were observed, and one order of higher corresponding effective capture cross-sections. All traps were found to be unaffected by the electric field during the field-dependent DLTS study. From the filling pulse width dependence DLTS study, a decrease in the capacitance transient amplitude with the increasing pulse width was observed opposite to the capture barrier kinetics of the traps and attributed to the emission of carriers during the capture process. Trap concentrations were found to be high at the interface using depth profiling DLTS. Based on the available literature, it is suggested that these traps are related to FeGa, Fe-related centers, and complexes with hydrogen or shallow donors, and might be affected or generated during metallization by the electron beam evaporator and chemical mechanical polishing.

Transient analysis of functionally graded axisymmetric plates via finite element method in the Laplace domain

The principal goal of this research article is to examine the forced vibration of Functionally Graded Material (FGM) axisymmetric plates with the aid of the finite element method in the Laplace space. The material properties are assumed to be isotropic, linear viscoelastic, or elastic and vary continuously in the direction of the thickness of the plate. The governing equations of motion are transferred to the Laplace domain and solved for a set of Laplace parameters. Then, a modified Durbin’s inverse Laplace method is employed to retransfer the obtained results back to the time domain. A convergence analysis is conducted to optimize the number of Laplace parameters and time steps. An 8-node quadratic quadrilateral element featuring two degrees of freedom per node is employed to generate the model of the axisymmetric plates. Different loads such as step load, square wave, and sawtooth wave loads are used to observe the impact of load type on the transient response of FGM plates. In viscoelastic analysis, the Kelvin damping model is preferred, and the effect of the damping ratio is investigated. The obtained results are validated with the aid of the available literature and the accuracy of the suggested model is confirmed. It is carried out that the material variation significantly affects the dynamic behavior of the plates, for instance as the material coefficient increases, displacement amplitudes decrease, and periods increase. The novelty of this paper is the employment of the finite element method together with Laplace transformation for addressing the present class of problems for the first time.

Experimental and theoretical studies of sea ice effects on internal solitary waves

Internal solitary waves in polar regions have attracted much interest recently. It is important to understand how sea ice affects them as this may have a profound influence on human activities and the environment. In this study, experiments on internal solitary waves with and without two types of sea ice (ice sheet and ice keel) are presented, as well as corresponding simulations using the Korteweg-de Vries (KdV) equation, the Benjamin-Ono (BO) equation, and the variable-coefficient Korteweg-de Vries (vKdV) equation, which is a derivation of the KdV equation. Comparison between experiments without sea ice and simulations using the KdV and BO equations proves the suitability of the former over the latter for this study. The experiments with sea ice and theoretical simulations using the vKdV equation provide evidence for wave deformation, oscillation occurring in the rear of the wave, and a decrease in amplitude. The latter suggests possibilities of energy dissipation or the emission of small amplitude linear waves. The sharp vertices of the ice result in occasional inconsistency with the vKdV predictions. Nonetheless, the vKdV equation is still suitable for modeling internal solitary waves under sea ice, giving generally accurate results that can assist further studies. This is the first time the vKdV equation has been applied to investigate the impacts of sea ice on internal solitary waves.

Effect of Stimulus Regularities on Eye Movement Characteristics

Humans have the unique ability to discern spatial and temporal regularities in their surroundings. However, the effect of learning these regularities on eye movement characteristics has not been studied enough. In the present study, we investigated the effect of the frequency of occurrence and the presence of common chunks in visual images on eye movement characteristics like the fixation duration, saccade amplitude and number, and gaze number across sequential experimental epochs. The participants had to discriminate the patterns presented in pairs as the same or different. The order of pairs was repeated six times. Our results show an increase in fixation duration and a decrease in saccade amplitude in the sequential epochs, suggesting a transition from ambient to focal information processing as participants acquire knowledge. This transition indicates deeper cognitive engagement and extended analysis of the stimulus information. Interestingly, contrary to our expectations, the saccade number increased, and the gaze number decreased. These unexpected results might imply a reduction in the memory load and a narrowing of attentional focus when the relevant stimulus characteristics are already determined.

Electrokinetic indices of erythrocytes as diagnostic criteria for preeclampsia

Objective. To evaluate the features of changes in the morphofunctional status of peripheral blood erythrocytes during normal pregnancy and in preeclampsia based on rapid analysis of biophysical parameters of cells.Materials and methods. A total of 136 pregnant women were examined at 22–24 and 34–35 weeks of gestation. The comparison groups included: 40 pregnant women with moderate preeclampsia (PE), 30 pregnant women with severe preeclampsia, 30 pregnant women with chronic arterial hypertension (CAH), 36 women with normal pregnancy who do not have signs of hypertensive disorders. Electrokinetic features of peripheral blood erythrocytes were studied using cellular microelectrophoresis, the average value of the amplitude of oscillations of mobile erythrocytes (μm) and the proportion of mobile cells (%) were analyzed.Results. At 22–24 weeks, the percentage of immobile erythrocytes in pregnant women with moderate PE increased by 2.8 times (p<0.05), the amplitude of oscillations of mobile cells decreased by 21% (p<0.05). In pregnant women with severe PE, the proportion of immobile erythrocytes increased by 3.2 times (p<0.05), the amplitude decreased by 30% (p<0.05). In pregnant women with CAH, a slight increase in the percentage of immobile cells (8.2 vs 6.8%) and a tendency to a decrease in the average amplitude (21.5 vs 23.2 μm) were noted. At 34–35 weeks in the group with moderate PE, the% of immobile erythrocytes exceeded the corresponding indicator in women with physiological pregnancy by 3.3 times (p<0.05), the average amplitude decreased by 28% (p<0.05), in pregnant women with severe PE, the% of immobile erythrocytes increased by 3.7 times (p<0.05), the amplitude decreased by 36% (p<0.05). In pregnant women with CAH, there was a tendency for a slight increase in the proportion of immobile erythrocytes.Conclusion. The functional and morphological usefulness of erythrocytes as active participants in the pathogenesis of preeclampsia can be objectively assessed using indicators of electrokinetic activity of cells, and erythrocytes can be considered as biomarkers of the disease and a promising tool for stratifying patients for early detection of high-risk pregnancies.

The effect of aspect ratio and mass ratio on the flow-induced flutter of a thin flexible sheet

This study experimentally investigates the flow-induced flutter of a thin flexible sheet, focusing on how the sheet's aspect ratio and mass ratio affect its stability and flutter characteristics in the post-critical regime. The flutter frequency of the sheet was obtained using hotwire measurements, while flutter amplitude and mode shape were acquired through high-speed imaging. The flowfield around the flapping sheet was analyzed using particle image velocimetry (PIV). Based on experimental observations, we report the onset of flutter as a subcritical bifurcation with hysteresis. The dynamic characteristics of the sheet play a significant role in its flutter instability, with the onset and cessation of flutter occurring at a frequency close to the sheet's second-mode natural frequency. The results show that both aspect ratio and mass ratio significantly affect the critical wind speed and flutter characteristics in the post-critical regime. Both flutter frequency and amplitude decrease as the aspect ratio decreases. PIV measurements in various planes reveal the highly three-dimensional nature of the flow. Results from off-axis PIV show a pair of counter-rotating spiral vortices in the wake that oscillate and change orientation with the sheet's movement. Additionally, a theoretical analysis was conducted to derive an approximate analytical relationship between the aspect ratio and critical wind speed. Experimental results aligned well with theoretical predictions for sheets with low aspect ratios (aspect ratio ≤1) but deviated for sheets with higher aspect ratios (aspect ratio >1). The relevant scaling parameters have also been explored to represent the experimental data in a non-dimensional form.

Experimental research on nonlinear vibration characteristics of double-layer mining string for deep-sea hydrate extraction under internal and external flow excitation

The vibration mechanism of the deep-sea hydrate mining string is extremely complex due to the combined effects of internal gas–liquid solid multiphase flow, structural contact collision, soil creep effect, and external ocean random load. Based on this, using the principle of similarity, a simulation experimental platform for the vibration of double-layer mining riser in deep-sea hydrate wells under internal and external flow excitation is developed, considering the vortex-induced effect of external flow field on the mining riser in the ocean section (which can simulate a maximum ocean flow velocity of 0.5 m/s), the three-phase flow-induced effect of gas–liquid–solid inside (which can simulate a maximum flow velocity of 2.0 m/s), and the coupling effect of mining string–conductor anchor node (CAN)–seabed. The influence of particle size, phase ratio, three-phase flow, and external flow velocity on the vibration response characteristics and nonlinear behavior of mining string are investigated. It is found that the vibration of vertical string is significantly affected by external ocean currents and internal three-phase currents. The vibration displacement amplitude of the horizontal section (average 0.08 mm) is significantly smaller than those of the vertical section (average 70 mm). The strong vibration positions of the vertical and horizontal sections of the mining string are different, in that the vertical section is mostly located below the middle section (just at 1800–2400 mm), while the horizontal section is mostly located at the three-phase inlet (just at 500 mm). The vertical section of the mining string presents a motion trajectory of oblique straight line, wide oblique straight line, or approximately wide oblique straight line, while the horizontal section is mostly a chaotic trajectory or an “8”-shaped chaotic trajectory. The decrease in particle mesh size and the increase in solid-phase proportion are reflected in the difficulty and accumulation of particle transport, leading to an increase in vibration displacement, as well as a decrease in vibration displacement amplitude and vibration energy. When the particle size set as 50 mesh, the displacement of mining string is largest, just for 110 mm of vertical section and 0.08 mm of horizontal section. The increase in the proportion of gas phase will lead to changes in the flow state of multiphase flow, which will affect the vibration displacement amplitude of the mining string to varying degrees. The increase in three-phase flow velocity further induces vibration of the mining string, and when the flow velocity is between 1.5 and 1.75 m/s, it will resonate with the string system, resulting in a sudden increase in the amplitude of vibration displacement. The research results can effectively guide operations and improve the service life of deep-sea hydrate mining riser.

Characterization of pore water distribution in unsaturated soils during drying process with NMR and soil-water characteristic curves

The soil–water characteristic curve, which illustrates the relationship between water content and matric suction, is crucial for both unsaturated soil theory and engineering applications. Since water content significantly affects unsaturated soil strength, experimentally examine the distribution of water within the soil matrix. First, three types of soil are prepared for nuclear magnetic resonance and pressure plate tests, conducted over a range of matric suctions from 0 to 1400 kPa. Then, the pressure plate testreveals that matric suction expels free water first, leaving bound water, which remains until reaching critical suction point. NMR test is also performed to analyze the dynamics of pore water distribution during drying process. As matric suction increases, the peak of signal amplitude decreases, shifting leftward, reflecting water drainage from larger to smaller pores. In addition, two drainage stages are identified, considering distinct ranges of matric suction. Large pores drain more quickly, while smaller pores retain water for a longer period, challenging simpler models of pore drainage. The dynamic distribution of pore water reveals the evolution of water expulsion from the soil over time. This sheds light on water distribution and drainage behavior, emphasizing the need for advanced models that account for pore connectivity and water retention mechanisms.

ВПЛИВ ПОКАЗНИКІВ ПРУЖНОСТІ ГУМОВОГО ЕЛЕМЕНТА ОПОРИ ДВИГУНА НА ПЕРЕДАЧУ ВІБРАЦІЙ НА КУЗОВ АВТОМОБІЛЯ

This paper presents the results of studies of the influence of the deformation characteristics of the rubber elements of the left support of the Z14XEP engine on the damping of vibrations transmitted to the body of the Opel Astra G (F69) when it operates at idle speed. For a clear description of the vibrations that occurred, their amplitude-frequency characteristics were measured using the Steval-mki062v1 multi-sensor module and the INEMO Software Tool, which made it possible to graphically obtain vibration oscillograms. It was found that the vibration frequencies are almost the same for the new and used supports, and the deviation values have a slight spread. It follows that the rubber element of the supports does not absorb vibrations in terms of vibration frequency. When a new support is installed, both the amplitude of oscillations and the deviations from their average values decrease. This is more pronounced in the transverse direction, where the amplitude decreases by 1.4 times and the deviation by 4.1 times, and in the vertical direction, where the amplitude decreases by 1.2 times and the deviation by 1.4 times. In the longitudinal direction, taking into account the values of the deviations, the amplitude has almost not changed, but its manifestation has become 5.5 times more uniform in terms of the value of the deviation. To construct the deformation characteristic of the rubber element, a classical technique was used, according to which it was loaded and unloaded in stages with a step of 1 mm through a mechanical dynamometer. The deformation characteristics made it possible to determine the normal stiffness of the rubber material and the pattern of hysteresis losses. And the time of restoring the current size of the rubber element during unloading made it possible to indirectly determine the resistance to the reverse movement of the axis of the distributed spring-loaded mass of the engine, which passes through the bolt in the support, which helps to level the vibration and absorb it in the volume of rubber. In the absence of perceptible vibrations on the body when a new support is installed, it is determined that the stiffness of its rubber element should not exceed cP = 0.45±0.02 kN‧mm-1 with a size recovery rate of no more than Vf = 4 μm‧s-1 within the operating load. The proposed methodology for determining the indicators of the deformation characteristics of a rubber element can be used during the direct diagnosis of engine bearings that have already been used and dismantled from cars during their disassembly to determine the feasibility of installing them in a regular place, if necessary, during current repairs.

Neuronal basis of high frequency fMRI fluctuation: direct evidence from simultaneous recording.

Resting-state functional magnetic resonance imaging (RS-fMRI) has been extensively utilized for noninvasive investigation of human brain activity. While studies employing simultaneous recordings of fMRI and electrophysiology have established a connection between the low-frequency fluctuation (< 0.1 Hz) observed in RS-fMRI and the local field potential (LFP), it remains unclear whether the RS-fMRI signal exhibits frequency-dependent modulation, which is a well-documented phenomenon in LFP. The present study concurrently recorded resting-state functional magnetic resonance imaging (RS-fMRI) and local field potentials (LFP) in the striatum of 8 rats before and after a pharmacological manipulation. We observed a highly similar frequency-dependent pattern of amplitude changes in both RS-fMRI and LFP following the manipulation, specifically an increase in high-frequency band amplitudes accompanied by a decrease in low-frequency band amplitudes. These findings provide direct evidence that the enhanced high-frequency fluctuations and reduced low-frequency fluctuations observed in RS-fMRI may reflect heightened neuronal activity.

Quantifying cardiac tissue heterogeneity using high-density grid catheter: validation in porcine model

Abstract Background and Objectives Characterizing cardiac substrate is crucial for diagnosing and treating cardiac arrhythmias due to its association with the presence of fibrotic tissue. Omnipolar Electrogram (EGM) technology provides orientation-independent signal generation and instantaneous propagation direction determination. Although traditionally, the amplitude of the bipolar signal has been the most used metric, it alone does not suffice for comprehensive tissue characterization. Recently, a novel metric has been developed to quantify the degree of directional propagation disorganization within cardiac tissue, defined as Vector Field Heterogenity (VFH)[1] that can provide additional insights to the tissue characterization. Due to the presence of tissues with varying impedance, changes in the direction of propagation of cardiac electrical signals can occur. Therefore, the objective of this study is to characterize how the presence of fibrotic or necrotic tissue can influence the disorganization of electrical activity propagation, and thus assess the effectiveness of the heterogeneity metric in characterizing these tissues. Method We worked with a database of a female swine records of the left atrium. These records include data pre and post-ablation by electroporation. From the unipolar signals available in the database, we have calculated the Omnipolar EGMs in cross configuration. From the omnipolar signals, we calculated the propagation direction. On this propagation direction, we applied the heterogeneity metric for each catheter position along all the left atrium. This metric has a normalized range between 0 and 1, 0 describing the minimum disorganization and 1 the maximum. These calculations have been applied in the same way in the registers pre and post-ablation to evaluate the differences. Results Pre-procedure bipolar peak-to-peak voltages averaged 2.7591mV (SD = 3.4257), decreasing post-procedure to 0.754mV (SD = 1.1666), (p&amp;lt; 0.0001) indicating a significant decrease in bipolar amplitude following ablation. Heterogeneity scores increased post-ablation (mean = 0.3753, SD = 0.21218; post: mean = 0.53526, SD = 0.1320, p&amp;lt;0.0001. This indicates that after ablation, not only does the signal amplitude decrease, but also the level of disorganization of electrical propagation increases. These findings are visually depicted in Figure 1. Conclusion The ablation procedure led to reduced tissue electrical activity, manifested by decreased amplitude and increased propagation heterogeneity, indicative of tissue disorganization. Transitioning from homogeneous to heterogeneous conduction post-ablation suggests the presence of necrotic tissue, hindering uniform wave propagation. This highlights the significance of heterogeneity scoring in evaluating tissue health and ablative intervention outcomes.Figure 1.Catheter HD Grid

Numerical modelling of bridge deck reinforcement corrosion based on analysis of GPR data

AbstractThis study explores the impact of corrosion on Ground Penetrating Radar (GPR) responses through practical experiments and numerical modelling, focusing on rebar diameter reduction, corrosion product layer thickness, crack formation and corrosion product filling in vertical and transverse crack. Practical experiments involved GPR testing of reinforced concrete slab. By analyzing B-scans we identify areas with moderate and severe corrosion. Numerical modelling using the Finite Difference Time Domain (FDTD) Method to model GPR signal propagation in a concrete bridge deck with corrosion is applied. Key finding includes a significant 26.70% increase in reflected wave amplitude when corrosion product filling in vertical crack increased by 400%, highlighting its extensive effect on signal GPR propagation. Reduced rebar diameter led to a 9.79% amplitude decrease and a 0.06 ns arrival time delay. Increased corrosion product layer thickness primarily affected arrival time with a 0.06 ns extension but significantly amplified GPR signal amplitude. These findings offer insights for improving GPR based corrosion detection and assessment methods, leading to more robust systems for concrete bridge deck inspection and maintenance. This paper contributes to understanding how corrosion affects the signal that is detected by GPR. This information can be used to improve the way that we manage and assess corrosion in concrete bridge deck.