Drop In Amplitude Research Articles

Safe distance from facial nerve for bipolar coagulation in parotid surgery-Animal study.

Currently no data exist on what distance from facial nerve (FN) it is safe to perform bipolar cautery (BC) in parotid surgery, although frequently performed. The degree of damage was measured using continuous intraoperative neuromonitoring (cIONM, NIM™ 3, Medtronic) in 16 Wistar rats. Amplitude drop of at least 50% (A50) or a loss of signal (LOS) in the cIONM was defined as harmful; BC was performed in power range 20-60 W. BC ≤30 W did not cause LOS (0/14 nerves). When applying 35 W, A50 occurred at 4 mm from FN and LOS was noted in 1 of 5 nerves. BC at a power of 40 to 60 W demonstrated LOS in all nerves (12/12) at a 5 mm distance. BC up to 30 W can be safely applied up to 3 mm distance from FN. 40 to 60 W should be avoided and used only at a distance of over 6 mm from FN. NA/animal study. Laryngoscope, 2024.

Damage Diagnosis in RC Frames on a Frequency Domain Basis

Today, there are many methods for detecting damages in reinforced concrete structures, such as pushover analysis, energy-based analysis and nonlinear analysis in the time domain. These methods are used to determine the dynamic properties of the structure by using accelerometers and a number of measuring devices that determine the mechanical and physical properties of the structure. In this study, it is aimed to diagnose damage with a set of frequencies and corresponding amplitude values obtained from accelerometers that determine the dynamic properties of the structure, instead of these methods that create calculation complexity. In this study, firstly, the damaged elements and joint points of the 1-storey RC frame with a single opening in both directions were determined by pushover analysis, for which the finite element model was built in the SAP2000 program. Later, time history analyzes were carried out under the influence of acceleration data of the Pazarcık earthquake (Mw 7.7) that occurred on February 6. The results obtained in the time domain were converted into the frequency domain and some inferences were made regarding the damaged areas. The study results showed that if the amplitude drop decreases in the same frequency range at a node, damage occurs at that node. It has been determined that the damages occurring in the RC frame increase due to the decrease in amplitude.

Spectral and timing properties of the accreting millisecond X-ray pulsar IGR J17498-2921 during its 2023 outburst

We present a comprehensive study of the spectral properties of the accreting millisecond X-ray pulsar IGR J17498$-$2921 during its 2023 outburst. Similar to other accreting millisecond X-ray pulsars, the broadband spectral emission observed quasi-simultaneously by NICER and NuSTAR is well described by an absorbed Comptonized emission with an electron temperature of sim 17 keV plus a disk reflection component. The broadening of the disk reflection spectral features, such as a prominent iron emission line at 6.4--6.7 keV, is consistent with the relativistic motion of matter in a disk truncated at sim $21 \ R_g $ from the source, near the Keplerian corotation radius. From the high-cadence monitoring data obtained with NICER, we observed that the evolution of the photon index and the temperature of seed photons tracks variations in the X-ray flux. This is particularly evident close to a sudden sim -0.25 cycle jump in the pulse phase, which occurs immediately following an X-ray flux flare and a drop in the pulse amplitude below the $3 detection threshold. We also report on the non-detection of optical pulsations with TNG/SiFAP2 from the highly absorbed optical counterpart.

Phenotypic Characterisation of Obstructive Sleep Apnoea in Acute Coronary Syndrome

Recent neutral randomised clinical trials have created clinical equipoise for treating obstructive sleep apnoea (OSA) for managing cardiovascular risk. The importance of defining the links between OSA and cardiovascular disease is needed with the aim of advancing the robustness of future clinical trials. We aimed to define the clinical correlates and characterise surrogate cardiovascular markers in patients with acute coronary syndrome (ACS) and OSA. Overall, 66 patients diagnosed with ACS were studied. Patients underwent an unattended polysomnogram after hospital discharge (median [interquartile range] 62 [37-132] days). The Epworth Sleepiness Scale, Berlin, and STOP-BANG questionnaires were administered. Surrogate measures of vascular structure and function, and cardiovascular autonomic function were conducted. Pulse wave amplitude drop was derived from the pulse oximetry signals of the overnight polysomnogram. OSA (apnoea-hypopnea index [AHI] ≥5) was diagnosed in 94% of patients. Moderate-to-severe OSA (AHI≥15) was observed in 68% of patients. Daytime sleepiness (Epworth Sleepiness Scale ≥10) was reported in 17% of patients. OSA screening questionnaires were inadequate to identify moderate-to-severe OSA, with an area under the receiver operating characteristic curve of approximately 0.64. Arterial stiffness (carotid-femoral pulse wave velocity, 6.1 [5.2-6.8] vs 7.4 [6.6-8.6] m/s, p=0.002) and carotid intima-media thickness (0.8 [0.7-1.0] vs 0.9 [0.8-1.0] mm, p=0.027) was elevated in patients with moderate-to-severe OSA. After adjusting for age, sex and body mass index, these relationships were not statistically significant. No relationships were observed in other surrogate cardiovascular markers. A high prevalence of OSA in a mostly non-sleepy population with ACS was identified, highlighting a gross underdiagnosis of OSA among cardiovascular patients. The limitations of OSA screening questionnaires highlight the need for new models of OSA screening as part of cardiovascular risk management. A range of inconsistent abnormalities were observed in measures of vascular structure and function, and these appear to be largely explained by confounding factors. Further research is required to elucidate biomarkers for the presence and impact of OSA in ACS patients.

Amplitude Parameters Are Predictive of Hearing Preservation in a Randomized Controlled Trial of Intracochlear Electrocochleography During Cochlear Implant Surgery.

To prospectively evaluate the association between hearing preservation after cochlear implantation (CI) and intracochlear electrocochleography (ECochG) amplitude parameters. Multi-institutional, prospective randomized clinical trial. Ten high-volume, tertiary care CI centers. Adults (n = 87) with sensorineural hearing loss meeting CI criteria (2018-2021) with audiometric thresholds of ≤80 dB HL at 500 Hz. Participants were randomized to CI surgery with or without audible ECochG monitoring. Electrode arrays were inserted to the full-depth marker. Hearing preservation was determined by comparing pre-CI, unaided low-frequency (125-, 250-, and 500-Hz) pure-tone average (LF-PTA) to LF-PTA at CI activation. Three ECochG amplitude parameters were analyzed: 1) insertion track patterns, 2) magnitude of ECochG amplitude change, and 3) total number of ECochG amplitude drops. The Type CC insertion track pattern, representing corrected drops in ECochG amplitude, was seen in 76% of cases with ECochG "on," compared with 24% of cases with ECochG "off" ( p = 0.003). The magnitude of ECochG signal drop was significantly correlated with the amount of LF-PTA change pre-CI and post-CI ( p < 0.05). The mean number of amplitude drops during electrode insertion was significantly correlated with change in LF-PTA at activation and 3 months post-CI ( p ≤ 0.01). ECochG amplitude parameters during CI surgery have important prognostic utility. Higher incidence of Type CC in ECochG "on" suggests that monitoring may be useful for surgeons in order to recover the ECochG signal and preventing potentially traumatic electrode-cochlear interactions.

Incipient instability real-time warning via adaptive wavelet synchrosqueezed transform: Onboard applications from compressors to gas turbine engines

To address the limitations of existing stall/surge warning methods—including variations in research subjects, sensor configurations, computational complexity, and the universality of thresholds—this study proposes a novel incipient instability warning approach utilizing adaptive wavelet synchrosqueezed transform. Each detection cycle begins with the acquisition of a low-pass filtered and downsampled total pressure signal from the compressor outlet, captured via a sliding window to represent the pressure sample. Then, the adaptive wavelet synchrosqueezed transform (AWSST), employing dynamic discretization with scales and synchrosqueezing technology, analyzes the real-time pressure sample to extract precise instantaneous frequency changes at low computational costs. Features of instability severity are derived from the amplitude, phase, and pressure drop within the time-frequency spectrum, leading to the formulation of a warning logic. The proposed method's effectiveness and universality are validated through hardware-in-loop (HIL) tests using multiple surge test data. Results show that the proposed method outperforms traditional real-time warning methods, which rely on the pressure change rate, by enhancing accuracy and advancing warning times by 15 ms–50 ms. Notably, the threshold is universal for compressors or engines of the same model. By increasing the acceptable performance decline criteria, compressors, turbofan engines, and turboshaft engines can employ a common set of thresholds.

SMART Pass automatic deactivation of subcutaneous implantable cardioverter-defibrillators

BackgroundThe SMART Pass algorithm for subcutaneous implantable cardioverter-defibrillator prevents inappropriate shocks due to oversensing. The mechanisms and significance of SMART Pass deactivation remain unclear. ObjectiveThe objective of this study was to assess whether SMART Pass deactivation is associated with inappropriate shocks and to elucidate the underlying mechanism. MethodsWe retrospectively investigated 115 patients who underwent subcutaneous implantable cardioverter-defibrillator implantation between 2016 and 2021. SMART Pass deactivation and inappropriate shocks during follow-up were assessed. The QRS amplitudes of the subcutaneous (S-ECG) and 12-lead electrocardiogram (ECG) at the time of implantation (pre) and SMART Pass deactivation (post) were measured. The patients were divided into the SP-ON group with SMART Pass consistently on and the SP-OFF group with the experience of SMART Pass deactivation. ResultsThree of 12 patients in the SP-OFF group experienced inappropriate shocks during a median follow-up of 1094 (interquartile range, 887–1502) days compared with 4 of 87 patients in the SP-ON group. Pre- and post–S-ECG QRS amplitudes were significantly lower in the SP-OFF group than in the SP-ON group (both P < .05), despite similar 12-lead ECG QRS amplitude in both groups. A significant temporary drop in the QRS amplitude of the S-ECG led to SMART Pass deactivation (pre–QRS amplitude vs amplitude at deactivation, P = .015; 95% CI, 0.3–1.9). ConclusionThe rate of inappropriate shocks was numerically higher after SMART Pass deactivation. A low QRS amplitude in S-ECG was a potential risk factor for SMART Pass deactivation. Careful follow-up and suitable management are required for managing patients with risks of SMART Pass deactivation.

The Inter-Phase Gap Offset Effect as a Measure of Neural Health in Cochlear Implant Users With Residual Acoustic Hearing.

The inter-phase gap (IPG) offset effect is defined as the dB offset between the linear parts of electrically evoked compound action potential (ECAP) amplitude growth functions for two stimuli differing only in IPG. The method was recently suggested to represent neural health in cochlear implant (CI) users while being unaffected by CI electrode impedances. Hereby, a larger IPG offset effect should reflect better neural health. The aims of the present study were to (1) examine whether the IPG offset effect negatively correlates with the ECAP threshold and the preoperative pure-tone average (PTA) in CI recipients with residual acoustic hearing and (2) investigate the dependency of the IPG offset effect on hair cell survival and intracochlear electrode impedances. Seventeen adult study participants with residual acoustic hearing at 500 Hz undergoing CI surgery at the University Hospital of Zurich were prospectively enrolled. ECAP thresholds, IPG offset effects, electrocochleography (ECochG) responses to 500 Hz tone bursts, and monopolar electrical impedances were obtained at an apical, middle, and basal electrode set during and between 4 and 12 weeks after CI surgery. Pure-tone audiometry was conducted within 3 weeks before surgery and approximately 6 weeks after surgery. Linear mixed regression analyses and t tests were performed to assess relationships between (changes in) ECAP threshold, IPG offset, impedance, PTA, and ECochG amplitude. The IPG offset effect positively correlated with the ECAP threshold in intraoperative recordings (p < 0.001) and did not significantly correlate with the preoperative PTA (p = 0.999). The IPG offset showed a postoperative decrease for electrode sets that showed an ECochG amplitude drop. This IPG offset decrease was significantly larger than for electrode sets that showed no ECochG amplitude decrease, t(17) = 2.76, p = 0.014. Linear mixed regression analysis showed no systematic effect of electrode impedance changes on the IPG offset effect (p = 0.263) but suggested a participant-dependent effect of electrode impedance on IPG offset. The present study results did not reveal the expected relationships between the IPG offset effect and ECAP threshold values or between the IPG offset effect and preoperative acoustic hearing. Changes in electrode impedance did not exhibit a direct impact on the IPG offset effect, although this impact might be individualized among CI recipients. Overall, our findings suggest that the interpretation and application of the IPG offset effect in clinical settings should be approached with caution considering its complex relationships with other cochlear and neural health metrics.

A Low-Complexity Beamformer for Ultrasound Imaging Based on Sub-Beamformer and Multi-Apodization With Cross-Correlation

ObjectiveThis paper proposes an ultrasound imaging algorithm based on sub-beamformer and multi-apodization with cross-correlation (SUB-MAX), aiming to achieve high resolution close to the minimum variance (MV) beamforming with low complexity and to enhance image contrast while maintaining background quality. MethodsThe output of two (N/2)-element DAS beamformers with asymmetric phase centers is subtracted, resulting in a large drop in the main-lobe amplitude, while the sidelobe maintains a relatively high amplitude level. Inspired by this characteristic, the coefficients with opposite trends compared with the subtracted output are obtained and fused with the normalized cross-correlation (NCC) weighting matrix acquired by using multi-pair received apodization, the proposed SUB-MAX obtains a new weighting matrix to weight the output of the DAS beamformer. ResultsFor ats_wire point targets, the average full-width at half-maximum (FWHM) of SUB-MAX compared with DAS, DMAS, CF, and MAX decreases by 52.7%, 43.5%, 33.3%, and 52.7%, respectively. For geabr_0 cysts, the average contrast ratio (CR) of SUB-MAX compared with DAS, MV, DMAS, and CF increases by 57.7%, 86.8%, 2.5%, and 14.4%, respectively. Experiments on rat_tumor dataset also indicate that SUB-MAX has a superior comprehensive imaging performance. ConclusionThe experimental results indicate that the superior comprehensive imaging performance of the proposed SUB-MAX is expected to be suitable for real-time imaging systems due to its non-reliance on covariance matrix inversion.

Multimodal intraoperative neurophysiological monitoring with special emphasis on facial MEPs for facial nerve preservation in vestibular schwannoma surgeries: Surgical nuances and outcome predictability

Objectives: The objective of this study was to evaluate the utility of facial motor-evoked potentials (FMEPs) as a significant part of multimodal intraoperative neurophysiological monitoring (IONM) for preserving facial nerve (FN) function in vestibular schwannoma surgery guiding the resection, and predicting outcome. Materials and Methods: This prospective observational study included 35 cases of vestibular schwannomas operated under multimodal IONM using free-running electromyography (EMG), triggered EMG (with both monopolar probe and suction stimulator), FMEPs, electroencephalography and its spectral derivatives and train-of-four testing. Direct stimulation using a monopolar probe helped in the identification of FN and guiding tumour resection. The suction stimulator probe was used for quasi-continuous stimulus delivery and FN mapping. FMEPs helped in the assessment of the integrity of FN. Results: In 14 cases, there was a single instance, and in 11 cases, there was more than one instance of a significant drop in FMEPs. Sixteen cases had &gt;50% fall in FMEPs during surgery. In 28 cases, the proximal stimulation threshold for FN was ≤0.1 mA at the end of the tumour resection. At the end of the first week following surgery, only 42.9% of the cases had good functional preservation (House–Brackmann [HB] Grade I or II) of FN, which increased to 78.8% at the end of one year. The remaining 21.2% had HB Grade III weakness. Percentage drop in FMEP amplitude and final FMEP amplitude correlated significantly (P &lt; 0.01) with the post-operative HB Grade at 1st week, 3, 6 and 12 months following surgery. Conclusion: FMEPs, as a significant component of multimodal IONM, provide a real-time assessment of FN function during surgery, facilitate safe maximal resection, predict immediate post-operative FN outcomes, and improve long-term FN function by minimising the cumulative insult inflicted on the FN during surgery.

Numerical investigation of the vorticity transportation and energy dissipation in a variable speed pump-turbine

Variable speed technology is utilized in pump turbines to enhance their operational efficiency and stability. The unsteady internal flows of a variable speed pump turbine operating at different rotation speeds are numerically investigated with SST k-ω turbulence model. Firstly, the ideal rotating speed is selected for each output. Amongst three researched output levels, the lowest entropy production consistently occurs at minimum rotation speed,1350 rpm. Under similar outputs, higher rotation speeds result in higher entropy production. Difference between various rotation speed is up to 40 %. Secondly, Liutex method is used to structure the vortex while vorticity transport equation is applied to analyze its evolution. Results show that variable speed operation can effectively reduce pressure fluctuation amplitude with approximately 20 %–40 % amplitude drop. Subsequently, the relationship between vortex rope and entropy production in the draft tube is deeply explored as it reveals that entropy production in the draft tube correlates with vortex rope evolution. Moreover, direct dissipation's entropy production and turbulence dissipation's entropy production are two primary components leading to irreversible energy loss. It is clearly revealed that the entropy production reduces with rotation speed. The relationship between entropy production and vortex rope in the draft tube is confirmed.

Four-Point Impedance: A Potential Biomarker for Residual Hearing After Cochlear Implantation.

Preservation of residual hearing after cochlear implantation allows for electroacoustic stimulation, which leads to better music appreciation, noise localization, and speech comprehension in noisy environments. Real-time intraoperative electrocochleography (rt-ECochG) monitoring has shown promise in improving residual hearing rates. Four-point impedance (4PI) is being explored as a potential biomarker in cochlear implantation that has been associated with fibrotic tissue response, hearing loss, and dizziness. In this study, we explore whether monitoring both rt-ECochG intraoperatively and postoperative 4PI improves predictions of the preservation of residual hearing. This was a prospective cohort study. Adults with residual acoustic hearing underwent cochlear implantation with intraoperative intracochlear electrocochleography (ECochG) monitoring. The surgeon responded to a drop in ECochG signal amplitude of greater than 30% by a standardized manipulation of the electrode with the aim of restoring the ECochG. At the end of the procedure, the ECochG signal was categorized as being maintained or having dropped more than 30%. 4PI was measured on 1 day, 1 week, and 1 and 3 months after cochlear implantation. Residual hearing was measured by routine pure-tone audiogram at 3 months postoperatively. The ECochG category and 4PI impedance values were entered as factors in a multiple linear regression predicting the protection of residual hearing. Twenty-six patients were recruited. Rt-ECochG significantly predicted residual hearing at 3 months (t test; mean difference, 37.7%; p = 0.002). Inclusion of both 1-day or 3-month 4PI in a multiple linear regression with rt-ECochG markedly improved upon correlations with residual hearing compared with the rt-ECochG-only model (rt-ECochG and 1-d 4PI model, R2 = 0.67; rt-ECochG and 3-mo 4PI model, R2 = 0.72; rt-ECochG-only model, R2 = 0.33). Both rt-ECochG and 4PI predict preservation of residual hearing after cochlear implantation. These findings suggest that the biological response of the cochlea to implantation, as reflected in 4PI, is an important determinant of residual hearing, independent of the acute effects on hearing during implant surgery seen with rt-ECochG. We speculate that 4PI relates to inflammation 1 day after implantation and fibrosis at 3 months.

Gain-Bandwidth Product Compensation Technique by 16-Unit Tail Current Control for a Radiation Tolerant Preamplifier With 0.9% Amplitude Drop up to 5 Mrad

Gain-Bandwidth Product Compensation Technique by 16-Unit Tail Current Control for a Radiation Tolerant Preamplifier With 0.9% Amplitude Drop up to 5 Mrad

Diverging Polymer Acoustic Lens Design for High-Resolution Row-Column Array Ultrasound Transducers.

Spherical diverging acoustic lenses mounted on flat 2-D row-column-addressed (RCA) ultrasound transducers have shown the potential to extend the field of view (FOV) from a rectilinear to a curvilinear volume region and, thereby, enable 3-D imaging of large organs. Such lenses are usually designed for small aperture low-frequency transducers, which have limited resolution. Moreover, they are made of off-the-shelf pieces of materials, which leaves no room for optimization. We hypothesize that acoustic lenses can be designed to fit high-resolution transducers, and they can be fabricated in a fast, cost-effective, and flexible manner using a combination of 3-D printing and casting or computer numerical control (CNC) machining techniques. These lenses should increase the FOV of the array while preserving the image quality. In this work, such lenses are made in concave, convex, and compound spherical shapes and from thermoplastics and thermosetting polymers. Polymethylpentene (TPX), polystyrene (PS), polypropylene (PP), polymethyl methacrylate (PMMA), polydimethylsiloxane (PDMS), and room-temperature-vulcanizing (RTV) silicone diverging lenses have been fabricated and mounted on a 128 + 128 6-MHz RCA transducer. The performances of the lenses have been assessed and compared in terms of FOV, signal-to-noise ratio (SNR), bandwidth, and potential artifacts. The largest FOV (24.0.) is obtained with a 42.64-mm radius PMMA-RTV compound lens, which maintains a decent fractional bandwidth (53%) and SNR at 6 MHz (.9.1-dB amplitude drop compared with the unlensed transducer). The simple PMMA TPX, PS, PP, PDMS, and RTV lenses provide an FOV of 12.2°, 6.3°, 8.1°, 11.7°, 0.6°, and 10.4°; a fractional bandwidth of 97%, 46%, 103%, 46%, 97%, 53%, and 49%; and an amplitude drop of -5.2, -4.4, -2.8, -15.4, -6.0, and -1.8 dB, respectively. This work demonstrates that thermoplastics are suitable materials for fabricating low-attenuation convex diverging lenses for large-aperture, high-frequency 2-D transducers. This is highly desired to achieve high-resolution volumetric imaging of large organs.

Continuous intraoperative neuromonitoring of the facial nerve predicts postoperative facial palsy in parotid surgery: a prospective study.

Facial palsy (FP) is the most significant complication of parotidectomy. Currently, the use of intermittent intraoperative neuromonitoring (iIONM) in parotid surgery facilitates nerve detection, which is paramount to nerve protection. Continuous IONM (cIONM), as applied in thyroid surgery, enables real-time information on electrophysiological nerve status through continuous nerve stimulation, thereby allowing consequent amplitude analysis. To date, the application of cIONM in parotid surgery has not been noted in literature. We performed parotidectomies with anterograde facial nerve visualization using cIONM in 32 consecutive patients in a prospective study (German Register of clinical studies-DRKS 00011051) during the period October 2016 to January 2020. After the facial trunk had been exposed, an atraumatic stimulation electrode was placed and the nerve was stimulated at 3Hz, at a low threshold (0.62 ± 0.06mA), for the entire duration of the preparation. Selected electrophysiological parameters were collected and compared to postoperative facial nerve function, measured by the House-Brackmann grading system. In the post hoc analysis, a significant correlation between a drop in amplitude (< 50% of the "baseline" amplitude) and postoperative FP was recorded (p = 0.001). True positive prediction of FP was noted in 14 out of 16 patients and true negative in 10 out of 16. The sensitivity was 87.5% (AUC 0.75), with a high negative predictive value of 83.3%. cIONM has significant value in predicting postoperative FP in parotidectomy. Future development of an acoustic/optic warning system in IONM devices could prevent nerve injury in real time.

Evaluation and comparison of impedance and amplitude changes in lesion index-guided pulmonary vein isolation.

The lesion index (LSI) has been used to estimate lesion formation after radiofrequency catheter ablation. However, the impedance drop and decrease in bipolar amplitude of intracardiac electrograms, which are parameters that are traditionally used to predict effective ablation lesions, are not used to calculate LSI. Therefore, we aimed to investigate the association between LSI and traditional parameters. We retrospectively investigated 1355 ablation points from 31 patients who underwent LSI-guided pulmonary vein isolation (PVI) using TactiCath. All points were classified into 3 groups based on the impedance drop: (i) <10 Ω (n = 67), (ii) 10-20 Ω (n = 909), and (iii) >20 Ω (n = 379). The LSI targets were 4.5 for the posterior left atrium and 5.2 for the anterior left atrium. After excluding 583 points at which it was difficult to measure the amplitude, 772 ablation points during sinus rhythm were included in the analysis of bipolar amplitude. The target LSI was achieved at 1177 points (86.9%). The median total impedance drop and amplitude just after ablation were 16.0 [13.0-20.0] Ω and 0.21 [0.14-0.30] mV, respectively. There were significant differences among the 3 groups in the impedance and amplitude before ablation, power, target LSI, final LSI, contact force, and interlesion distance. An impedance drop of >10 Ω or an amplitude reduction of >50% was achieved at 95% and 82% of the study points, respectively. There were no major complications at any of the ablation points. LSI-guided PVI seemed to be useful for making sufficient ablation lesions, as assessed by the conventional parameters of impedance and amplitude change.

Passive elimination of flow-induced forces and vibrations of a circular cylinder using a slit

Here, passive flow control technique of incorporating a slit through a circular structure is utilized to dampen the flow-induced vibration (FIV). The study is segregated into two main sections, one where the effect of slit width ratio (S/D) and Reynolds number (Re) is investigated on the fixed stationary cylinder, and the other where the effect of slit size is explored on the behavior of the elastically mounted cylinder with varying reduced velocities (Ur) at Re = 100. The slit width ratio is varied from 0% (no slit) to 50% and Re from 100 to 300 for a stationary cylinder. For elastically mounted cylinder, the mass (m* = 5) and damping (ζ = 0.01) ratios and Re (100) are fixed, whereas Ur is varied from 0 to 10. The results are expressed as coefficient of lift and drag, Strouhal number, amplitude and frequency of vibration, force-displacement plots, and vorticity contours. They indicate that the presence of a slit reduces the lift and drag coefficients and suppresses the FIV. At Re = 100, the presence of 10% and 20% slit decreases the lift coefficient by 13.0% and 71.8%, respectively, as compared to the solid cylinder. Considering the maximum amplitude of vibration, a 10% slit resulted in a 5.7% amplitude drop, whilst a 20% slit resulted in a significant drop of 34.4% as compared to the solid cylinder. Further increasing the slit size from 20% to 30% completely vanished the vortex shedding and led to steady flow with zero lift and no vibration.

Thiazole Derivatives as Modulators of GluA2 AMPA Receptors: Potent Allosteric Effects and Neuroprotective Potential.

Thiazole carboxamide derivatives were synthesized in this investigation, with a subsequent examination of their impact on GluA2 AMPA receptors. The synthesized compounds, namely MMH-1-5, were subjected to characterization using high-resolution mass spectrometry (HRMS), proton nuclear magnetic resonance (1H-NMR), and carbon-13 nuclear magnetic resonance (13C-NMR). The present work thoroughly investigates the impact of five thiazole derivatives on GluA2 AMPA receptors. This investigation examined their effects on both whole-cell currents and receptor kinetics. In addition, the cytotoxicity of the samples was assessed using the MTS test. The compound MMH-5 had the highest effect level, resulting in a notable drop in current amplitude by a factor of six. Similarly, MMH-4 and MMH-3 also caused major reductions in the current amplitude. The compounds mentioned above also influenced the rates of deactivation and desensitization. MMH-5 and MMH-4 exhibited an increase in deactivation, while MMH-5 showed reduced desensitization. Our research findings highlight the efficacy of MMH-5 as a negative allosteric modulator of GluA2 AMPA receptors, exerting substantial effects on both the magnitude and time course of receptor activity. Significantly, the compound MMH-2 demonstrated noteworthy cytotoxic effects, as evidenced by cell viability rates dropping below 6.79% for all cancer cell lines and 17.52% for the normal cell line (LX-2). Of particular interest is the pronounced cytotoxicity observed in MMH-5, suggesting its potential as a safe neuroprotective agent targeting the AMPA receptor, as indicated by cell viability percentages exceeding 85.44% across all cancer and normal cell lines. Docking simulations were performed to determine possible modes of interaction between MMH5 and the GluA2-AMPA receptor (PDB:7RZ5). The abovementioned facts and the well-documented effects of further thiazole derivatives provide a strong foundation for future research endeavors to enhance tailored treatments for neurological disorders that rely heavily on GluA2 signaling. The present study elucidates the intricate association between thiazole derivatives and GluA2 receptors, providing valuable perspectives on the prospects of enhanced and specific therapeutic interventions for diverse neurological conditions.

The use of acoustic emission in assessing the ductility loss in steel products under the effect of impact

Acoustic emission (AE) diagnostics was carried out during tensile testing of 20KhN2MA steel samples to study the loss of ductility after the impact. We used V-notched samples (3.3 mm in depth) with overall dimensions of 300 × 20 × 6 mm. The impact in the concentrator zone caused the depletion of the plasticity of the material, which was accompanied by a decrease in the partial fraction of ductile fracture and an increase in brittle fracture. The test samples were divided into six batches. The samples of the first batch were not subjected to the impact. In the second batch, the impact energy was 50 J, in the third — 75 J, in the fourth — 100 J, in the fifth — 125 J and in the sixth — 150 J. The rupture tests were carried out at room temperature and at a speed of the movable traverse of 1 mm/min. The kinetics of damage in the notch zone during loading was monitored using the acoustic emission (AE) method and video recording. Processes of brittle and ductile (caused by cleavage and shear, respectively) destruction of the crystal lattice of a metal differ primarily in the speed and duration of stress waves. To separate AE pulses generated by these processes, spectrograms of time-frequency transformations and waveforms were analyzed. Pulse selection was carried out using a complex parameter reflecting the steepness of the amplitude drop at the phase of signal attenuation. Boundary values were determined that allow separation of the recorded pulses into flows caused by ductile and brittle structural damage to structural steels. It is shown that manifestation of the effect of impact on the exhaustion of the plastic properties of steel 20KhN2MA becomes noticeable when the level of specific work exceeds 50 J/cm2. Moreover, with an increase in the specific work up to 150 J/cm2, the weight content of location pulses characterizing the kinetics of brittle destruction of structural bonds increased by 3 – 4 times, relative to that recorded for the samples without impact. This result correlates with the duration of the rupture test of the samples, which was reduced by three times when the level of the specific work increased to 150 J/cm2

P038 Characterising Pulse Wave Amplitude Drops in Patients with Acute Coronary Syndrome

Abstract Pulse wave amplitude derived from photoplethysmography signals is a surrogate measure of autonomic function and vascular response. Recent studies have demonstrated low pulse wave amplitude drop(PWAD) index to be associated with increased cardiovascular risk in obstructive sleep apnoea(OSA). The nature of PWAD in patients with cardiovascular disease remains unknown. We aimed to characterize PWAD in patients with acute coronary syndrome(ACS) diagnosed with OSA in terms of cardiovascular measures. We studied 70 patients with ACS (age:58[52,63]years, BMI:27[24,30]kg/m2). A level 2 polysomnogram was conducted to confirm OSA diagnosis within 6 months after discharge. Cardiovascular measures of heart rate variability(HRV), baroreflex sensitivity, pulse wave velocity (PWV) and endothelial function(FMD) were measured. PWAD was analysed using a validated algorithm. PWAD with an amplitude reduction of &amp;gt;30% from baseline and a duration &amp;gt;4 heartbeats were identified. PWAD frequency, duration, amplitude, area under the curve(AUC), descending and ascending slopes were calculated. There was no relationship between PWAD frequency and AHI (r=0.057, p=0.642). PWAD amplitude (rs= 0.308, p=0.031) and duration (rs= -0.319, p= 0.025) correlated with baroreflex effectiveness index. After controlling for age, gender and BMI, baroreflex effectiveness index was associated with PWAD duration (β±SE: -0.009±0.003, p=0.009). Aortic augmentation index correlated with PWAD duration (rs= 0.3565, p=0.0041). HRV parameters, FMD and PWV did not correlate with PWAD parameters (data not shown). These preliminary findings suggest PWAD duration and amplitude are not associated with OSA severity in patients with ACS. However PWAD may be appropriate markers of vascular and autonomic nervous system response in patients with cardiovascular disease.