Significant Increase In Amplitude Research Articles

Does the audiogram shape influence the intracochlear recording of Electrocochleography during and after cochlear implantation?

During cochlear implant (CI) surgery, it is desirable to perform intraoperative measurements such as Electrocochleography (ECochG) to monitor the inner ear function and thereby to support the preservation of residual hearing. However, a significant challenge arises as the recording location of intracochlear ECochG via the CI electrode changes during electrode insertion. This study aimed to investigate the relationships between intracochlear ECochG recordings, the position of the recording contact within the cochlea relative to its anatomy, and the implications for frequency and residual hearing preservation. Intraoperative ECochG recordings were conducted using the CI electrode (MED-EL) during the insertion of hearing preservation electrodes and after the insertion process. Recordings were continuously conducted using the most apical electrode (contact 1) during insertion. After insertion, the recordings were performed on all different electrode contacts. The electrode location in the cochlea during insertion was estimated using mathematical models and preoperative clinical imaging, while the postoperative electrode position was determined using postoperative clinical imaging. The study involved 10 adult CI recipients. In those with good low-frequency hearing, an increase in signal amplitude was observed, with the highest amplitudes closest to the stimulation frequency generators, and no phase change was observed. Conversely, patients with flat hearing loss exhibited a second peak with an opposite phase in the medial area of the cochlea. This study is the first to suggest that the pattern of the preoperative audiogram may influence the ECochG outcomes measured intraoperatively. Specifically, the ECochG responses during insertion appeared to behave as expected with good low-frequency hearing, while with flat hearing loss there appear to be further effects. These findings indicate that this approach can provide valuable information for the interpretation of intracochlearly recorded ECochG signals.

External Factors Influence on Defects Detection by Scanning Contact Potentiometry

Scanning contact potentiometry (SCP) method was used to detect structural inhomogeneities in a welded joint under the application of heat and constant electric current. For this purpose, a special sample was prepared, welded by manual arc welding from two halves of X8CrNiTi18-10 (Chromium-Nickel-titanium stainless Steel) austenitic steel, each with dimensions of 200×110×13.5mm. After welding, welded sample was inspected using X-ray radiography. The sample was stored for five months at room temperature, and the sample surface was scanned using different scanning speed ranging from 0.36 to 1.8 mm/sec. It was found that when scanning speed was increased, the signal values remained the same. In another experiment, a constant electric current was passed through the sample from 0.01 to 0.1A. Applying current led to the excitation of weak structural inhomogeneities from the welding joint butt, although it was machined. While heat led to an increase in diagnostic signal amplitude.

Dynamic and flow instability analysis during runaway process for a pump turbine

A power failure in the pump condition combined with the rejection of the guide vanes can cause the unit to runaway, which represents a dangerous transitional process for pumped storage power stations. This process is accompanied by intense oscillations in internal flow, pressure fluctuations, and changes runner forces. This study aims to clarify the unstable flow characteristics during the runaway process by focusing on the transient behaviour from the pump condition to the runaway condition in a high-head model pump turbine. The numerical calculation of the runaway speed and discharge are consistent with experimental test results. The results indicate that the dynamic curve is not continuously stable during the process but exhibits dynamic oscillations before reaching a relatively stable condition. Significant pressure fluctuations with high amplitudes are observed in the pump braking zone and close the runaway condition. Further analysis reveals low frequency, high amplitude pressure fluctuations within various flow components at frequencies smaller than the runner rotational frequency (fn). Axial forces demonstrate a linear correlation with the change rate of discharge. The dynamic evolution of the backflow vortex at the runner inlet is the main cause of significant fluctuations in the axial forces of the runner. The scale of the backflow vortex gradually increases as the discharge decreases, peaking in the pump braking zone. Entering the turbine operating condition, its intensity decreases to some extent but with a significantly expanded range. Near the optimal operating condition, the internal flow around the runner becomes smooth. As the discharge further decreases, the backflow vortex scale gradually increases, eventually forming a ring structure at the runner inlet. Further analysis indicates that the dynamic evolution of the backflow vortex at the runner inlet inevitably disrupts the flow, leading to a significant increase in pressure fluctuation amplitudes and more pronounced oscillations in axial forces.

Diacerein and myo-inositol alleviate letrozole-induced PCOS via modulation of HMGB1, SIRT1, and NF-kB: A comparative study.

Polycystic ovary syndrome (PCOS) is the most prevalent cause of anovulatory infertility in women. Myo-inositol supplementation has displayed effectiveness in curing PCOS patients. Diacerein, an anti-inflammatory medication, has not been extensively studied in the context of reproductive disorders. This study aimed to compare the role of myo-inositol and diacerein in PCOS and the probable mechanisms mediating their actions. Forty adult female rats were divided equally into the following: control, PCOS, PCOS+Myo-inositol, and PCOS+Diacerein groups. Rats were subjected to arterial blood pressure (ABP), electromyography (EMG), and uterine reactivity measurements. Blood samples were collected for measuring hormonal assays, glycemic state, lipid profile, oxidative stress, and inflammatory markers. Ovaries and uteri were extracted for histological examination, including hematoxylin and eosin staining, Masson's trichrome staining, immunohistochemistry, and rt-PCR analysis of ovarian tissues. PCOS was associated with significant increases in ABP, uterine frequency and amplitude of contraction, luteinizing hormone, testosterone, lipid, glycemic and inflammatory markers, malondialdehyde, high-mobility group box 1 (HMGB1), nuclear factor kappa (NF-kB), ovarian fibrosis, and endometrial thickening. In contrast, there was a significant reduction in follicular stimulating hormone, reduced glutathione, and Sirtuin 1 (SIRT1) when compared with control group. Both myo-inositol and diacerein counteract PCOS changes; but diacerein's effectswere superiorto myo-inositol's for all parameters, except for lipid and glycemic markers. Diacerein possessed anti-inflammatory properties and showed significant efficacy in mitigating the endocrinal, metabolic, and ovarian structural alterations linked to PCOS. Its beneficial actions likely stem from reducing oxidative stress, dyslipidemia, and hyperglycemia, potentially through the modulation of HMGB1, SIRT1, and NF-kB pathways.

Long-term impact of nusinersen on motor and electrophysiological outcomes in adolescent and adult spinal muscular atrophy: insights from a multicenter retrospective study.

5q spinal muscular atrophy (SMA) is a progressive autosomal recessive motor neuron disease. We aimed to assess the effects of nusinersen on motor function and electrophysiological parameters in adolescent and adult patients with 5q SMA. Patients with genetically confirmed 5q SMA were eligible for inclusion, and clinical data were collected at baseline (V1), 63days (V4), 180days (V5), and 300days (V6). The efficacy of nusinersen was monitored by encompassing clinical assessments, including the Revised Upper Limb Module (RULM), Hammersmith Functional Motor Scale Expanded (HFMSE), 6-Minute Walk Test (6MWT), and percent-predicted Forced Vital Capacity in sitting position (FVC%) and Compound Muscle Action Potential (CMAP) amplitude. The patients were divided into "sitter" and "walker" subgroups according to motor function status. 54 patients were screened, divided into "sitter" (N = 22) and "walker" (N = 32), with the mean age at baseline of 27.03years (range 13-53years). The HFMSE in the walker subgroup increased significantly from baseline to V4 (mean change +2.32-point, P = 0.004), V5 (+3.09, P = 0.004) and V6 (+4.21, P = 0.005). The patients in both the sitter and walker subgroup had no significant changes in mean RULM between V1 and the following time points. Significant increases in CMAP amplitudes were observed in both upper and lower limbs after treatment. Also, patients with RULM ≥ 36 points showed significant CMAP improvements. Our analysis predicted that patients with CMAP amplitudes of trapezius ≥ 1.76mV were more likely to achieve significant motor function improvements. Nusinersen effectively improves motor function and electrophysiological data in adolescent and adult patients with SMA. This is the first report on the CMAP amplitude changes in the trapezius after treatment in patients with SMA. The CMAP values effectively compensate for the ceiling effect observed in the RULM, suggesting that CMAP could serve as an additional biomarker for evaluating treatment efficacy.

Exploring Weak Magnetic Signal Characteristics of Pipeline Welds: Insights into Stress Non-Uniformity Effects.

Weak magnetic detection technology can detect stress concentration areas in ferromagnetic materials. However, the stress non-uniform characteristics of pipeline welds lead to significant differences in stress distribution range and values between inner wall welds and outer wall welds. This discrepancy makes it crucial to further evaluate the impact of stress non-uniformity on magnetic signals. To study the magnetic signal characteristics under the influence of residual stress in weld seams, a magneto-mechanical analytical model was established based on the magnetic charge theory and the distribution characteristics of residual stress in the weld seam. The magneto-mechanical relationship and magnetic signal distribution characteristics at the inner and outer wall welds of the pipeline are calculated. Furthermore, the effects of different excitation intensities on the amplitude growth characteristics of magnetic signals are analyzed and compared. To verify the analysis model, weld detection experiments with different excitation intensities were designed. The results show that both the peak-to-valley values of the normal component and the peak values of the tangential component of the outer wall weld are lower than those of the inner wall weld. Conversely, the peak-to-valley width of the normal component and the peak width of the tangential component are greater than those of the inner wall weld. Additionally, the rate of increase in weak magnetic signal amplitude decreases in a first-order exponential relationship with increasing excitation intensity. The average decay rates of the normal and tangential component amplitude growth rates for the inner wall weld are 34.03% and 27.9%, respectively, while for the outer wall weld, they are 31.75% and 28.01%, respectively. This study contributes to the identification and quantitative assessment of weak magnetic signals in inner and outer wall welds.

When the Heart Meets the Mind: Exploring the Brain-Heart Interaction during Time Perception.

Recent studies suggest that time estimation relies on bodily rhythms and interoceptive signals. We provide the first direct electrophysiological evidence suggesting an association between the brain's processing of heartbeat and duration judgment. We examined heartbeat-evoked potential (HEP) and contingent negative variation (CNV) during an auditory duration-reproduction task and a control reaction-time task spanning 4, 8, and 12 s intervals, in both male and female participants. Interoceptive awareness was assessed with the Self-Awareness Questionnaire (SAQ) and interoceptive accuracy through the heartbeat-counting task (HCT). Results revealed that SAQ scores, but not the HCT, correlated with mean reproduced durations with higher SAQ scores associating with longer and more accurate duration reproductions. Notably, the HEP amplitude changes during the encoding phase of the timing task, particularly within 130-270 ms (HEP1) and 470-520 ms (HEP2) after the R-peak, demonstrated interval-specific modulations that did not emerge in the control task. A significant ramp-like increase in HEP2 amplitudes occurred during the duration-encoding phase of the timing but not during the control task. This increase within the reproduction phase of the timing task correlated significantly with the reproduced durations for the 8 s and the 4 s intervals. The larger the increase in HEP2, the greater the under-reproduction of the estimated duration. CNV components during the encoding phase of the timing task were more negative than those in the reaction-time task, suggesting greater executive resources orientation toward time. We conclude that interoceptive awareness (SAQ) and cortical responses to heartbeats (HEP) predict duration reproductions, emphasizing the embodied nature of time.

Ultrasound propagation characteristics within the bone tissue of miniature ultrasound probes: implications for the spinal navigation of pedicle screw placement.

The accuracy of pedicle screw fixation is crucial for patient safety. Traditional navigation methods based on computed tomography (CT) imaging have several limitations. Therefore, this study aimed to investigate the ultrasonic propagation characteristics of bone tissue and their relationship with CT imaging results, as well as the potential application of ultrasound navigation in pedicle screw fixation. The study used three bovine spine specimens (BSSs) and five human vertebral allograft bones (HABs) to progressively decrease the thickness of the cancellous bone layer, simulating the process of pedicle screw perforation. Five unfocused miniature ultrasound probes with frequencies of 2.2, 2.5, 3, 12, and 30 MHz were employed for investigating the ultrasonic propagation characteristics of cancellous and cortical bone through ultrasound transmission and backscatter experiments. The CT features of the bone tissue was obtained with the Skyscan 1174 micro-CT scanner (Bruker, Billerica, MA, USA). The experimental results demonstrated that low-frequency (2-3 MHz) ultrasound effectively penetrated the cancellous bone layer up to a depth of approximately 5 mm, with an attenuation coefficient below 10 dB/cm. Conversely, high-frequency (12 MHz) ultrasound exhibited significant signal attenuation in cancellous bone, reaching up to 55.8 dB/cm. The amplitude of the backscattered signal at the cancellous bone interface exhibited a negative correlation with the bone sample thickness (average r=-0.84), meaning that as the thickness of the cancellous bone layer on the cortical bone decreases, the backscattered signal amplitude gradually increases (P<0.05). Upon reaching the cortical bone interface, there was a rapid surge in echo signal amplitude, up to 8 times higher. Meanwhile, the statistical results indicated a significant correlation between the amplitude of the echo signal and the micro-CT scanning results of bone trabecular structure. Theoretically, using multiple ultrasonic probes (≥3) and regions of interest (ROIs) (≥5) has the potential to provide surgeons with early warning signals for pedicle perforation based on three or more successive increases in echo signal amplitude or a sudden substantial increase. The statistical results indicate a significant correlation between the amplitude of the echo signal and the micro-CT scanning results of bone trabeculae, suggesting the potential use of ultrasound as opposed to CT for real-time intraoperative bone navigation.

Efficacy of 100 hz sound stimulation on saccular dysfunction in meniere’s disease

Background Although various medical remedies have been attempted to alleviate the symptoms of Meniere’s disease (MD), the risk–benefit ratios of these various treatments remain debatable. Objective We investigated the efficacy of sound stimulation of 100 Hz for treating vestibular dysfunction in patients with Meniere’s disease (MD). Materials and methods Patients with definitive MD with intractable vestibular symptoms and endolymphatic hydrops (EH) in the inner ear were evaluated. The experimental group received sound stimulation of 75 dB at a frequency of 100 Hz for 5 min, and the control group received sound stimulation of 75 dB at a frequency of 250 Hz for 5 min. Cervical vestibular-evoked myogenic potentials (cVEMPs) were measured before and after each sound stimulation, and the results of the clinical tests were compared between the two patient groups. Results Significant increases in cVEMP amplitudes were observed after sound stimulation of 100 Hz in ears with vestibular endolymphatic hydrops, although no such improvement was observed in the control group. Conclusion Sound stimulation of 75 dB at a frequency of 100 Hz leads to improvement in cVEMP amplitude in patients with definitive MD. Adequate sound stimulation might be a new method for treating vestibular dysfunction associated with MD.

Acute effects of aerobic exercise on corticomotor plasticity in individuals with and without depression

BackgroundAlthough complex in nature, the pathophysiology of depression involves reduced or impaired neuroplastic capabilities. Restoring or enhancing neuroplasticity may serve as a treatment target for developing therapies for depression. Aerobic exercise (AEx) has antidepressant benefits and may enhance neuroplasticity in depression although the latter has yet to be substantiated. Therefore, we sought to examine the acute effect of AEx on neuroplasticity in depression. MethodsSixteen individuals with (DEP; 13 female; age = 28.5 ± 7.3; Montgomery-Äsberg Depression Rating Scale [MADRS] = 21.3 ± 5.2) and without depression (HC; 13 female; age 27.2 ± 7.5; MADRS = 0.8 ± 1.2) completed three experimental visits consisting of 15 min of low intensity AEx (LO) at 35% heart rate reserve (HRR), high intensity AEx (HI) at 70% HRR, or sitting (CON). Following AEx, excitatory paired associative stimulation (PAS25ms) was employed to probe neuroplasticity. Motor evoked potentials (MEP) were assessed via transcranial magnetic stimulation before and after PAS25ms to indicate acute changes in neuroplasticity. ResultsPAS25ms primed with HI AEx led to significant increases in MEP amplitude compared to LO and CON. HI AEx elicited enhanced PAS25ms-induced neuroplasticity for up to 1-h post-PAS. There were no significant between-group differences. ConclusionHI AEx enhances PAS measured neuroplasticity in individuals with and without depression. HI AEx may have a potent influence on the brain and serve as an effective primer, or adjunct, to therapies that seek to harness neuroplasticity.

Acoustic analog-to-digital converter using coupled waveguides in phononic crystals

In this research, a novel application as an acoustic analog-to-digital converter (ADC) is introduced, utilizing all-solid phononic crystals. The structure consists of a two-channel directional coupler designed to achieve 2-bit quantization. As the input signal amplitude increases, additional stress is applied to the background, inducing a slight change in the mass density of the phononic crystal structure. This structure is composed of an array of iron scatterers embedded in a polymerization of methyl methacrylate (PMMA) medium, with a selected working frequency of 67.5 kHz. To guide the applied acoustic wave, a directional coupler is employed. In the proposed model, transmission values below 0.3 are interpreted as "0," while values exceeding 0.3 are considered "1." It is crucial that a transmission range of 0.4–0.6 signifies a logical "1" for both active outputs. The fabrication tolerance of the directional coupler rods has been calculated, and the maximum transmission change is equal to 0.03 in a 2 µm changing range around the central radius

Vagus nerve stimulation in bursts can efficiently modulate gastric contractions and contraction frequency at varying gastric pressures.

There has been recent clinical interest in the use of vagus nerve stimulation (VNS) for treating gastrointestinal disorders as an alternative to drugs or gastric electrical stimulation. However, effectiveness of burst stimulation has not been demonstrated. We investigated the ability of bursting and continuous VNS to influence gastric and pyloric activity under a range of stimulation parameters and gastric pressures. The goals of this study were to determine which parameters could optimally excite or inhibit gastric activity. Data were collected from 21 Sprague-Dawley rats. Under urethane anesthesia, a rubber balloon was implanted into the stomach, connected to a pressure transducer and a saline infusion pump. A pressure catheter was inserted at the pyloric sphincter and a bipolar nerve cuff was implanted onto the left cervical vagus nerve. The balloon was filled to 15 cmH2O. Stimulation trials were conducted in a consistent order; the protocol was then repeated at 25 and 35 cmH2O. The nerve was then transected and stimulation repeated to investigate directionality of effects. Bursting stimulation at the bradycardia threshold caused significant increases in gastric contraction amplitude with entrainment to the bursting frequency. Some continuous stimulation trials could also cause increased contractions but without frequency changes. Few significant changes were observed at the pylorus, except for frequency entrainment. These effects could not be uniquely attributed to afferent or efferent activity. Our findings further elucidate the effects of different VNS parameters on the stomach and pylorus and provide a basis for future studies of bursting stimulation for gastric neuromodulation.

Study on multi-scale coupled simulation of natural circulation system with 3×3 petal-shaped fuel bundle channel under rolling condition

Petal-shaped fuel rod encompasses a broad application prospect in sea-based nuclear power plants. A multi-scale coupled simulation is conducted based on natural circulation system with 3×3 petal-shaped fuel bundle channel. A multi-scale coupled model considering rolling motion is developed. Its reliability is verified by existing experimental data. The effect of rolling motion on the characteristics of natural circulation system is thoroughly discussed. The results indicate that if the start-up direction of rolling motion is the same as the direction of flow rate, rolling motion will lead to a sharp decrease in flow rate at the initial moment. By increasing rolling amplitude or decreasing rolling period will cause a significant increase in fluctuation amplitude of flow rate. Compared with the results under static condition, the fluid is subjected to the Coriolis force in the non-inertial coordinate system. This research can provide support for the joint optimization of natural circulation system.

ARE THERE OBJECTIVE BIOMECHANICAL SYMPTOMS OF KNEE INSTABILITY AFTER ANTERIOR CRUCIATE LIGAMENT INJURY OR IT’S RECONSTRUCTION?

Background: Instability of the knee joint after rupture of the anterior cruciate ligament and even after its reconstruction remains a pressing problem. The use of a special functional test with fast walking can be considered as a potential tool for verifying instability.&#x0D; Aims: to find out whether there are biomechanical differences in joint function with and without instability, both in the period before and after anterior cruciate ligament reconstruction.&#x0D; Methods: A biomechanical study of the function of walking at fast speeds, including an electromyographic study, was used. 40 patients were examined, 22 underwent reconstruction of the anterior cruciate ligament. The patients were divided into two groups - with symptoms of instability - 33 people, and without them - 7 people and a control group (healthy) 20 people.&#x0D; Results: The time characteristics of the step cycle did not reveal significant differences between the groups and the control group. For the amplitudes of movements in the joints, there are also completely no significant differences between the parameters of one group from the other and the affected side from the intact side. Only for the intact side in the group with instability there is a significant increase in both amplitudes in the knee joint compared to the control. Electromyographic study also did not reveal significant differences.&#x0D; Conclusions: The use of a functional test with fast walking does not allow differentiating the state of instability. Thus, the instability of the knee joint during normal walking, even at high speed, does not manifest itself in any way. To detect it, it is necessary to develop special provocative tests.

Effects of blood-feeding on mosquitoes hovering kinematics and aerodynamics

Mosquitoes exhibit a distinctive and remarkable flight pattern, flapping their wings at a high frequency with relatively small stroke amplitude. However, until recently, the underlying aerodynamic mechanisms have remained unclear. Furthermore, there is a lack of understanding about their flight behaviors after blood-feeding and the corresponding aerodynamic characteristics. This study aims to explore this uncharted area, conducts experiments to acquire kinematic and morphological data and numerical simulations to obtain three-dimensional flow characteristic. Further analysis uncovers several key findings. Both before and after blood-feeding hovering exhibit a similar flapping wing pattern, characterized by downstroke and upstroke with three stages of each half stroke. After blood-feeding, there are significant increases in stroke amplitude, mid-downstroke duration, velocity, and flip angles. Additionally, body pitch, stroke plane tilt, and Reynolds number experience increments. In hovering, mosquitoes balance vertical force with weight, with substantial peaks observed in each stage, particularly during the mid-stroke. After blood-feeding, the vertical force experiences a 3.3-fold increase, with the majority of the increase occurring during the mid-downstroke. The study identifies three unsteady mechanisms for aerodynamic force generation without blood-feeding hovering, namely, added-mass force, delayed stall, and fast-pitching-up rotation. These mechanisms persist after blood-feeding, with a greater reliance on delayed stall to support increased weight.

A Prospective, Monocentric Case-Control Study on Uncontrolled Psoriasis as Independent Risk Factor for a Hypercoagulable State.

Chronic inflammatory diseases, including psoriasis, are associated with development of venous thromboembolism (VTE). The clot lysis profile (CLP) provides information on both the clotting tendency and fibrinolysis activity. We hypothesized that CLP in uncontrolled psoriasis patients is disturbed towards more clotting/less lysis compared to healthy controls (HC) and that successful psoriasis treatment could normalize the CLP. In this project, we aim to compare the CLP in patients with uncontrolled psoriasis with age- and sex-matched HC and investigate the effect of anti-inflammatory treatment on CLP. Patients with uncontrolled psoriasis [psoriasis area severity index (PASI) or body surface area (BSA) > 10] (n = 87) and HC (n = 87) were recruited at a tertiary dermatology department. Samples from patients were obtained before treatment and when disease control was obtained (PASI < 3). Amplitude, area under the curve (AUC) and 50% clot lysis time were determined. At baseline, psoriasis patients had higher median amplitude and AUC compared with HC (p < 0.0001). After correction for possible confounders (BMI, smoking behavior, psoriatic arthritis, arterial hypertension, diabetes and coronary artery disease), the increased amplitude in psoriasis patients compared to HC remained significant. Successful anti-inflammatory treatment resulted in a significant decrease in amplitude (p = 0.0365). This is the first prospective study comparing the CLP of psoriasis patients with that of HC. A significant increase in both amplitude and area under the curve, indicative of a hypercoagulable CLP, was observed in psoriasis patients compared to HC. After successful anti-inflammatory treatment, amplitude significantly decreased.

The Effect of Mixing Iodinated Contrast Media and Ultrasound Contrast Agents on Subharmonic Signals.

Subharmonic aided pressure estimation (SHAPE) is a technique that utilizes subharmonic signals from microbubble contrast agents for pressure estimation. Validation of the SHAPE technique relies on synchronous measurements of in vivo pressures using contrast microbubbles and a pressure catheter (reference standard). For the guidance and placement of pressure catheter in vivo, iodinated contrast is used with fluoroscopy. Therefore, during data acquisition for validation studies of the SHAPE technique, both contrast microbubbles and iodinated contrast are present simultaneously within the vasculature. This study aims to elucidate the effects of iodinated contrast (Visipaque, GE HealthCare) on subharmonic signal amplitude from contrast microbubbles (Definity, Lantheus Medical Imaging, Inc.). In an acrylic water tank, 0.06 mL of Definity and varied amounts of Visipaque (0.14, 0.43, 0.85, and 1.70 mL) were added to 425 mL of deionized water. Ultrasound scanning was performed with a SonixTablet scanner (BK Medical Systems) using optimized parameters for SHAPE with Definity (ftransmit/receive = 3.0/1.5 MHz; chirp down pulse). Subharmonic data was acquired and analyzed at 9 different incident acoustic outputs (n = 3). Results showed an increase in subharmonic signal amplitude from Definity microbubbles in the presence of 0.14 mL Visipaque by 2.8 ± 1.3 dB (p < .001), no change with 0.85 mL Visipaque (0.7 ± 1.2 dB; p = .09) and a decrease in subharmonic amplitude in the presence of 1.70 mL Visipaque by 1.9 ± 0.7 dB (p < .001). While statistically significant effect on subharmonic signal amplitude of Definity microbubbles was noted due to the mixture, the magnitude of the effect was minimal (~2.8 dB) and unlikely to impact in vivo SHAPE measurements.

Carbon nanofibers/liquid metal composites for high temperature laser ultrasound

As the demand for clean energy becomes greater worldwide, there will also be an increasing demand for next generation nuclear power plants that incorporate advanced sensors and monitoring equipment. A major challenge posed by nuclear power plants is that, during normal operation, the reactor compartment is subjected to high operating temperatures and radiation flux. Diagnostic sensors monitoring such structures are also subject to temperatures reaching hundreds of degrees Celsius, which puts them at risk for heat degradation. In this work, the ability of carbon nanofibers to work in conjunction with a liquid metal as a photoacoustic transmitter was demonstrated at high temperatures. Fields metal, a Bi-In-Sn eutectic, and gallium are compared as acoustic mediums. Fields metal was shown experimentally to have superior performance over gallium and other reference cases. Under stimulation from a low fluence 6 ns pulse laser at 6 mJ/cm2 with 532 nm green light, the Fields metal transducer transmitted a 200 kHz longitudinal wave with amplitude >5.5 times that generated by a gallium transducer at 300 °C. Each high temperature test was conducted from a hot to cold progression, beginning as high as 300 °C, and then cooling down to 100 °C. Each test shows increasing signal amplitude of the liquid metal transducers as temperature decreases. Carbon nanofibers show a strong improvement over previously used candle-soot nanoparticles in both their ability to produce strong acoustic signals and absorb higher laser fluences up to 12 mJ/cm2.

Exploring retro-cue effects on visual working memory: insights from double-cue paradigm.

In the realm of visual working memory research, the retro-cue paradigm helps us study retro-cue effects such as retro-cue benefit (RCB) and retro-cue cost (RCC). RCB reflects better performance with cued items, while RCC indicates poorer performance with uncued items. Despite consistent evidence for RCB, it's still uncertain whether it remains when previously uncued items are cued afterward. Additionally, research findings have been inconsistent. This study combines prior experiments by controlling the proportion of cue types and the number of memory items. Besides, using a CDA index to assess the status of items after the cue appeared. Results showed better performance under the double-cue condition (involving two cues pointing inconsistently with only the second cue being valid) compared to the neutral-cue condition, and better performance under the single-cue condition compared to double-cue. EEG data revealed that after the appearance of the second cue in the double-cue condition, there was a significant increase in CDA wave amplitude compared to the single-cue condition. Behavior results suggests that RCB occurs under double-cue but to a lesser extent than the single-cue. And EEG outcomes indicates that individuals did not remove the uncued item from their visual working memory after the first cue. Instead, they kept it in a passive state and then shifted it to an active state after the appearance of the second cue.

Mechanism and rule of microwave pulse response of two-stage PIN limiter

&lt;sec&gt;This paper aims to analyze the failure mechanism of the two-stage PIN limiter after having been injected by a microwave pulse. A two-stage PIN limiter model with high computational efficiency and accuracy is built by using the method of field-circuit collaborative simulation. Using this model, the temperature change of the PIN diodes during the injection of microwave pulse is simulated. The melting temperature of the PIN diode is selected as the failure criterion of the PIN limiter. The time and energy required for the failure of the PIN limiter under injection of microwave pulses with different frequencies and amplitudes are simulated. Furthermore, the mechanisms that trigger off these effects are analyzed. The relationship between the microwave pulse parameters and the PIN limiter failure time is summarized by using an empirical formula.&lt;/sec&gt;&lt;sec&gt;According to the simulation results, the temperature change of the second-stage PIN diode is relatively small compared with that of the first-stage. During the injection of the microwave pulse, the failure time and energy consumption of limiter show a certain regularity with the variation of microwave pulse amplitude and frequency, and this work discusses this regularity from the following three aspects. Firstly, the failure time and energy consumption decrease in a similar trend with frequency increasing. And with the increase in signal amplitude, the failure time and energy consumption tend to stabilize. Secondly, the increase in the signal amplitude leads failure time to decrease, which is similar to the relationship between failure time and the signal frequency mentioned before. But as the signal’s amplitude increases, the energy consumption first increases and then decreases slightly when the amplitude reaches about 900 V. Based on the theoretical analysis and the physical image of the two-stage PIN limiter, the reasons for these effects can be explained as the changes in the I-region's impedance and heat distribution change caused by electric field changes. Thirdly, the failure time and energy consumption show different sensitivities to different parameters of the microwave pulse. The signal frequency change has greater influence on the energy consumption than the signal amplitude change, while the amplitude change can exert a greater influence on the failure time than the frequency change.&lt;/sec&gt;