Pulse Peak Research Articles

Developing precision in WEDM machining of Mg-SiC nanocomposites using machine learning algorithms

Abstract Wire electrical discharge machining (WEDM) is one of the most commonly used non-conventional machining processes in the aerospace, nuclear, and precision industries. This technology possesses numerous advantages over traditional machining processes due to its superior properties, such as high precision of machined surfaces, ease of machining of complex shapes, and hard material processing. This study focuses on investigating the performance characteristics of Mg-SiC nanocomposite through experimental analysis using WEDM, with surface roughness as the key evaluation parameter. Employing a fractional factorial design, twenty-five experimental datasets were generated to explore the impact of WEDM machining parameters, including Pulse on time (Ton), Pulse off time (Toff), Servo voltage (SV), and Peak current (Ip), on surface roughness. Leveraging a machine learning approach, specifically, Support Vector Regression (SVR) integrated with Genetic Algorithms (GA) and Particle Swarm Optimization (PSO), an integrated predictive surface roughness model for machined substrates was developed. The predicted results exhibited a high level of agreement with experimental data, boasting a coefficient of determination (R2) value of 0.866 and a mean square error (MSE) of 0.364. A novel aspect of this work lies in integrating GA-PSO with SVR to obtain optimized surface roughness values. Through this methodology, SVR-GA and SVR-PSO achieved optimum surface roughness values of 0.187 μm and 0.132 μm, respectively, with SVR-PSO demonstrating superior performance by outperforming SVR-GA after 360 and 428 iterations, respectively. Thus, this study presents a novel and effective approach to optimizing surface roughness values in WEDM processes.

Visible-Light-Stimulated Optoelectronic Neuromorphic Transistor Based on Indium-Gallium-Zinc Oxide via Bi2Te3 Light Absorption Layer.

To emulate a visual perception system, a bismuth telluride (Bi2Te3)/indium-gallium-zinc oxide (IGZO) heterostructure is introduced for optoelectronic neuromorphic transistors (ONTs). Amorphous IGZO is applied as a channel layer to exhibit low off-current, high mobility, and persistent photoconductivity, enabling light-stimulated neuromorphic characteristics. The atomic ratio of In/Ga/Zn was 9.4:9.8:5.2. For a light absorption layer, Bi2Te3 is applied due to a small bandgap, high photoresponse, and carrier concentration. However, conventional optoelectronic devices using Bi2Te3 exhibit insufficient performance owing to their excessive conductivity. To resolve the constraint, the oxidation of Bi2Te3 is performed to suppress its electrical conductivity. Finally, the IGZO ONT with a Bi2Te3 layer exhibits optoelectronic characteristics under visible-light irradiation. Under red-light irradiation having a light intensity of 5 mW mm-2, it exhibits enhanced optoelectronic characteristics including photoresponsivity, photosensitivity, and detectivity from 19.6 to 3.46 × 102 A/W, 4.95 to 1.46 × 108, and 1.45 × 107 to 2.13 × 1012 Jones compared to that without a Bi2Te3 layer, respectively. To confirm reproducibility and uniformity, we fabricated and compared the optoelectronic characteristics of 5 samples from batch to batch. Regarding optoelectronic neuromorphic characteristics, the ONT exhibits short- and long-term memory and a highly linear relationship between peak synaptic current and pulse number under red-light pulses. The paired-pulse facilitation index was 208%. To confirm the applicability of artificial visual perception, a 6 × 6 ONT array demonstrates long-term memory characteristic successfully after red-light irradiation with a Y-shaped pattern. In view of stability and reliability, we conducted three potentiation processes and compared the peak synaptic currents of each potentiation process.

Switching, amplifying, and chirping diode lasers with current pulses for high bandwidth quantum technologies.

A series of simple and low-cost devices for switching, amplifying, and chirping diode lasers based on current modulation are presented. Direct modulation of diode laser currents is rarely sufficient to establish precise amplitude and phase control over light, as its effects on these parameters are not independent. These devices overcome this limitation by exploiting amplifier saturation and dramatically outperform commonly used external modulators in key figures of merit for quantum technological applications. Semiconductor optical amplifiers operated on either rubidium D line are recast as intensity switches and shown to achieve ON:OFF ratios >106 in as little as 50ns. Current is switched to a 795nm wavelength (Rb D1) tapered amplifier to produce optical pulses of few nanosecond duration and peak powers of 3 W at a similar extinction ratio. Fast rf pulses are applied directly to a laser diode to shift its emission frequency by up to 300MHz in either direction and at a maximum chirp rate of 150MHzns-1. Finally, the latter components are combined, yielding a system that produces watt-level optical pulses with arbitrary frequency chirps in the given range and <2% residual intensity variation, all within 65ns upon asynchronous demand. Such systems have broad application in atomic, molecular, and optical physics and are of particular interest to fast experiments simultaneously requiring high power and low noise, for example, quantum memory experiments with atomic vapors.

Effect of Exercise-Based Cardiac Rehabilitation on Patients With Chronic Heart Failure After Transcatheter Aortic Valve Replacement: A Randomized Controlled Trial.

The objective of this study was to assess the effect of exercise-based cardiac rehabilitation (CR) with individualized exercise prescription in patients with chronic heart failure (HF) undergoing transcatheter aortic valve replacement (TAVR) in a randomized controlled trial. A total of 60 patients with chronic HF who received TAVR treatment were randomly divided into the control group (n=30) and exercise training (ET) group (n=30). The control group was treated with conventional rehabilitation, and the ET group was given personalized exercise-based CR based on a cardiopulmonary exercise test (CPX). The CPX parameters, echocardiography, 6-minute walk test distance, and quality of life were evaluated in the two groups. All patients who completed symptom-restricted CPX showed no complications. After the 12-week rehabilitation period, the levels of anaerobic threshold, peak oxygen uptake, peak oxygen pulse, peak power, left ventricular ejection fraction, and 6-minute walk test distance in the ET group were significantly higher than those in the control group (P<.05). Scores on the Minnesota Life with Heart Failure Questionnaire in the ET group were lower than those in the control group (P <.05). Exercise-based CR significantly improves cardiopulmonary function, exercise tolerance, and quality of life in patients with chronic HF who undergo TAVR.

Impact resistance characteristics of pipeline system covered with W-shape elastic-porous metallic damper

As a novel elastic-porous damping material fabricated through entangled wire mesh, W-shape elastic-porous metallic damper (W-EPMD) is considered an ideal damping element for coated pipeline system due to the micro dry friction between metal wires, which induces energy dissipation. The complex interwoven cellular formations of metallic wire mesh pose challenges in characterizing its dynamic characteristics. In this work, the dynamic properties of the pipeline system covered with W-EPMD under various impact conditions, including the acceleration response and impact isolation coefficient, were investigated by numerical simulations and experimental analysis. Constitutive models used to characterize the hysteresis behavior of W-EPMD were introduced, comprising Yeoh and Bergström-Boyce models, and parameter identification were conducted through quasi-static experiments. The reliability of the established numerical model was confirmed through drop impact experiments. The results demonstrate that there is a maximum discrepancy of 9.1 % between the simulation predictions and experimental results of the stress-strain curve. The impact isolation coefficient of the pipeline system covered with W-EPMD exhibits a fluctuating trend with the rise of the pulse peak, while the maximum compression of W-EPMD steadily increases. During the pipeline impact process, the increased density of W-EPMD reduces the impact resistance of the pipeline system, while excessively low density leads to over-compression and structural damage to W-EPMD. Furthermore, the discrepancy of the acceleration response between experimental and numerical results under various excitation signals remain within 6 %, demonstrating that the hysteresis model effectively characterizes the impact resistance characteristics of the pipeline system covered the W-EPMD.

Numerical investigation of divided-pulse amplification assisted by a hollow core anti-resonant fiber

An all-fiber structure laser based on divided-pulse amplification technology and a hollow core anti-resonant fiber (HC-ARF) is proposed. We numerically investigate the process of divided-pulse amplification in the structure based on the vectorial nonlinear Schrödinger equations. By changing the splicing angle of the HC-ARF, a conventional soliton with 703 fs can be divided into two sub-pulses with orthogonal polarization states. After amplification and compression, the two sub-pulses are recombined into one pulse in an identical HC-ARF. The combining efficiency and limitations that originate from cross-phase modulation, self-phase modulation, fiber dispersion, and splicing angle are analyzed. Moreover, the number of sub-pulses can increase from two to eight to greatly suppress the accumulation of the nonlinear phase shifts, by using three segments HC-ARF with splicing angles of 45°. The simulation result indicates that the pulse peak power and average power can be greatly improved after amplifying and combining the eight sub-pulses. The work can provide what we believe to be a new method for achieving all-fiber high-peak and high-average power femtosecond lasers.

Abstract 4145857: The effect of homebase exercise training on single ventricle heart (SVH) function, exercise performance, body composition and quality of Life in children and adolescents living with a Fontan circulation

Objectives: Fontan patients have impaired exercise capacity. Exercise training has been shown to improve exercise performance. We aim to determine the effect of exercise training on SVH function, and its correlation with exercise capacity, body composition and self-reported QOL. Methods: 31 paediatric Fontan patients were prospectively recruited to complete 3x30 minute homebased HIIT sessions per week for 20 weeks. Baseline physical activity levels, including structured sports participation, daily step-counts and active-zone-minutes (AZM) were recorded by accelerometer (Fitbit inspire3). Patients were considered active if they met 2 of the 3 criteria: 1/Structured sports training ≥ 2 per week (moderate-vigorous intensity &gt;30 minutes) 2/Daily steps ≥ 10k 3/AZM ≥60 minutes per day Bio-impedance-analysis, cardiopulmonary exercise tests, echocardiography including deformation imaging and PedQL questionnaires were performed at baseline and upon completion. Results: 28 participants completed the programme. 86% had good compliance (completed &gt;45/60 sessions). 17 male (60.7%), mean age 14.3±2.03 years, 14 LV-dominant, 14 non-LV dominant (9RV, 5BiV). No serious adverse events reported. The exercise duration improved from 7.56±2.6 to 9.16±2.5 minutes, p&lt;0.001 and peak workload from 110±43.6 to 129±45.8 watts, p&lt;0.001. Indexed oxygen consumption (VO 2 /kg peak) improved from 30.9±7.1 to 32.2±7ml/min/kg, p=0.003 and oxygen pulse, O 2 pulse peak from 9.1±2.6 to 9.7±3 mL/beat, p&lt;0.001. Submaximal analysis showed normal %predicted VO2 (&gt;40%) and improvement of O 2 pulse, p=0.024. LV systolic function showed improved MAPSE from 1.65±0.2 to 1.86±0.2, p=0.017, and improved apical rotation from 2.3±3.8 to 5.9±3.1, p=0.043. RV systolic function showed improved TAPSE of 1.4±0.2 to 1.6±0.3, p=0.032 and FAC of 44±5.6% to 49±10.5%, p=0.170. Self-reported QOL scores were higher in Fontan children who were physically active at baseline, with a downward trend noted when poor compliance was evident (Child’s QOL V3.0 91.21±0.7 to 86.1±5.2, p=0.018 (Table 2). Although no significant change in body composition, a higher appendicular skeletal muscle mass, SMMa% and lower body fat% were noted pre and post exercise training in the active Fontan group (Table 3), Conclusions: We observed significant improvements in both the submaximal and peak exercise performance in paediatric Exercise training associated with improvement of single ventricle longitudinal systolic function and ventricular mechanics.

Abstract 4137186: No Room for Chronotropic Incompetence in Living Fontan Patients: Enhanced Heart Rate Increase in Response to Exercise to Compensate Low Stroke Volume Reserve

Background: Fontan patients reveal decreased peak exercise performance in combination with low peak heart rate (HR), which is frequently interpreted as chronological incompetence. This is counterproductive as HR increase has to be enhanced to compensate limited stroke volume increase in Fontan physiology. Methods: Cardiopulmonary exercise testing (CPET) data in asymptomatic Fontan patients and age-matched control subjects were retrospectively studied. Peak and submaximal CPET parameters were obtained by cycle ergometer. Chronotropic capacity was assessed by peak HR/peak [WR/kg] and submaximal slope of HR/[work rate (WR)/kg] (ΔHR/Δ[WR/kg]) for males and females, separately. Results: Table 1 presents CPET data of Fontan patients (51) and controls (65). Fontan patients showed significantly lower peak HR, peak WR, peak oxygen consumption (VO2)/kg, %predicted maximum VO2, and peak oxygen pulse (pOP)/kg than controls in both sexes whereas peak HR/peak [WR/kg] was significantly higher in Fontan patients, indicating higher HR at the maximum effort in Fontan patients than in controls. Fontan patients showed higher ΔHR/Δ[WR/kg], a marker for HR-dependency, and lower Δ[VO2/kg]/ΔHR, a surrogate of stroke volume, suggesting higher HR was compensating lower stroke volume during submaximal phase of exercise in Fontan patients. Figure 1 demonstrates a linear relationship between ΔHR/ΔWR and peak HR/peak WR in both sexes. Male Fontan patients revealed a comparable trend with controls, whereas female Fontan patients showed higher HR increase at the peak exercise effort than controls with the same ΔHR/ΔWR, suggesting more limited stroke volume reserve than male Fontan patients. Conclusions: Fontan patients showed higher HR-response to exercise than controls in both sexes due to limitation in stroke volume increase. Our data indicate that lower peak HR in Fontan patients results from early exhaustion due to limited stroke volume reserve rather than primary chronotropic incompetence.

Abstract 4137985: Impaired Skeletal Muscle Condition and Stroke Volume Reserve Characterize Poor Exercise Performance in Childhood Cancer Survivors

Background: Childhood cancer survivors (CCS) frequently show poor exercise performance, but its pathophysiology and clinical significance are poorly understood. Methods: Poor exercise performers, defined as peak oxygen consumption (VO2)/kg &lt; 80% of predicted maximum VO2/kg, were enrolled, including 40 CCS (20 males, 20 females) and 32 controls (15 males, 17 females) from 79 CCS and 147 age-matched controls, respectively. Peak and submaximal CPET parameters were compared between CCS and controls with poor exercise performance. Submaximal slope parameters represent a trend up to anaerobic threshold (AT). Results: Ages and anthropometric measurements (weight, height, and body mass index) were comparable between CCS and controls in both sexes (Table 1). Both resting and peak heart rate (HR) were significantly higher in CCS than in controls in males. There was no significant difference in peak VO2/kg, peak oxygen pulse (OP)/kg, peak respiratory exchange ratio, or VO2/kg at AT (VAT/kg) between CCS and controls in both sexes. Peak work rate (WR/kg) was significantly lower in CCS compared with that in controls in both sexes, suggesting reduced muscle strength in CCS. Figure 1 demonstrates decreased muscle mass/strength in CCS than in controls. In males, Δ[VO2/kg]/ ΔHR was significantly lower in CCS than in controls, indicating limited stroke volume reserve (SVR) in male CCS. In female, although there was no significant difference in Δ[VO2/kg]/ΔHR between CCS and controls, HR-dependency expressed by ΔHR/Δ[WR/kg] was significantly higher in CCS than in controls, suggesting impaired SVR. ΔVO2/ΔWR, a marker for physical conditioning, was comparable between CCS and controls in both sexes. Conclusions: Poor exercise performance in CCS is characterized mainly by decreased muscle mass/strength and impaired SVR for both sexs. Impaired SVR may be an early sign of subclinical cardiotoxicity. Poor exercise performance in CCS should be improved to prevent future cardiovascular complications.

Generation of switchable rectangular pulsed cylindrical vector beams in a 1.7 µm mode-locking all-fiber laser

In this paper, we demonstrate the generation of switchable rectangular pulsed cylindrical vector beams in a 1.7 µm mode-locking all-fiber laser by nonlinear amplifying loop mirror for the first time. Based on the nonlinear amplifying loop mirror mode-locking technology and mode selection coupler, the rectangular pulsed CVBs can be achieved and switched repeatedly and easily between the dissipative soliton resonance and noise-like pulse states. Furthermore, with the increasing of pump power, the duration of dissipative soliton resonance and noise-like pulse increase from 1.76 ns to 6.36 ns and 1.15 ns to 3.95 ns, respectively. In the meanwhile, both the peak power of dissipative soliton resonance and noise-like pulse are all clamped at 6 W all the time, showing the independence of clamped peak power and pulse type. Our work not only broadens wavelength range of switchable rectangular pulse, but also provides a novel pulse profile application of cylindrical vector beams.

Mid-infrared enhanced Raman soliton generation in an erbium-doped ZBLAN with record energy and peak power

The advancement of tunable ultrafast sources in the mid-infrared spectrum would bring about significant progress in various scientific fields. This study suggests a gain-modulation technique to increase the peak power and pulse energy of mid-infrared tunable Raman solitons. By utilizing a high-power 2-2.23 µm Raman soliton pulse as a pump source, mid-infrared Raman solitons within the 2-3.2 µm tuning range can be generated in a segment of Er3+: ZBLAN fiber. Additionally, the introduction of 976 nm pump light into the Er3+: ZBLAN fiber leverages the gain of Er3+ to amplify the frequency shift velocity and pulse energy of the Raman soliton. Consequently, the frequency shift range of the Raman soliton is extended to 3.5 µm, with peak power and pulse energy reaching 0.93 MW and 107 nJ, respectively. These achievements represent the highest peak power and energy levels of Raman solitons generated in mid-infrared fibers to date.

Non-linear optics for an online probing of the specific surface area of nanoparticles in the aerosol phase

In the present study the generation of non-linear optical (NLO) effects, such as second harmonic generation (SHG), by black carbon particles, also named soot, and by other types of nanoparticles in aerosol phase is quantified and analysed. Its potential for measuring the specific surface area of an aerosol is put forward. SHG is a Non Linear Optical phenomenon that is typically used in biosciences and fundamental physics and has shown to have large potential for the investigation of surface sensitive phenomena. It exists in two forms, coherent SHG and incoherent SHG, also named Hyper Rayleigh Scattering (HRS). While applications on particles in solution or organic molecules located on the surface of droplets exist, the SHG naturally induced by solid nanoparticles in aerosol phase without any SHG enhancing additive has neither been detected nor quantified yet. The present work aims at narrowing this gap by exposing a jet of well-characterized nanoaerosols to a femtosecond laser featuring high peak pulse energies allowing to induce NLO phenomena. The experiments are carried out in an innovative optical setup allowing to analyse the NLO response resolved in time, wavelength and angle, thus having the capability to isolate SHG from other phenomena, such as laser filamentation. The optical setup was calibrated in order to quantify the generated signal power and optimized in order to have a high sensitivity and in order to avoid NLO generation from its own optical elements. The results confirm that soot particles, as well as DEHS droplets and arc generated carbon nanoparticles, feature SHG at intensities that are more than 7 orders of magnitude smaller than that of static light scattering. SHG depends in particular on aggregate and/or monomer size. On the other hand, SHG induced by soot does not seem to depend on the organic or elementary carbon content. The experiments also show that the detected NLO signal increases linearly with particle surface area, independently of the particle shape or composition. Finally, the angular response of NLO signal is fundamentally different from that of linear scattering. Due to the isotropic nature of the angular response, the observed SHG signal is probably non-coherent and thus related to Hyper Raleigh Scattering. These findings show the potential of non-linear optics, in particular to quantify in situ the specific surface of an aerosol. Giving access to this information which is crucial in the evaluation of toxicity of aerosols, the present work can thus give way to a new class of laser based diagnostics for aerosols.

Various pulse nonlinear evolution and dynamics employing CuCrO2 nanocrystals as a promising saturable absorber

Considering that fiber lasers are a far richer nonlinear optical system, a systematical study on various pulse nonlinear evolution and dynamics by one SA has great significance. However, investigating these important pulse nonlinear dynamic evolution processes of CuCrO2 nanocrystals as new SAs applied in ultrafast fiber lasers has never been explored. Herein, we demonstrate the excellent nonlinear optical properties of CuCrO2 nanocrystals and investigate the potential of CuCrO2 nanocrystals for generating various pulse nonlinear dynamic evolution processes. Firstly, the output characteristics of the passively Q-switching pulsed fiber lasers have been regulated by using CuCrO2 nanocrystals-polyimide film and a tapered fiber. The pulse duration and repetition rate were simultaneously compressed by 10 and 222 times, the pulse energy and peak power were increased by 79 and 827 times, respectively. Secondly, we are able to generate chaotic multi-pulse wave packets and optical rogue waves by the polarization mode dispersion of single-mode fiber together with the non-instantaneous relaxation of CuCrO2 nanocrystals. Finally, the transition from chaotic multi-pulse wave packet to giant chirped mode-locked pulse is realized by introducing high nonlinear fibers. Our results show that CuCrO2 nanocrystals are an efficient nonlinear material for studying various nonlinear phenomena, and give a new impetus to the development of nonlinear optics and ultrafast photonics.

Development of an inductive energy storage pulsed power supply using SiC semiconductor devices for ozone production by streamer discharges

An inductive energy storage (IES) pulsed power generator driven by a silicon carbide metal oxide semiconductor field effect transistor (SiC-MOSFET) with a blocking voltage of 1.2 kV was developed. The IES pulsed power generator consists of a capacitor, a pulsed transformer and the SiC-MOSFET used as an opening switch. The influence of the turn ratio of the pulsed transformer on the output voltage was evaluated. The output voltage amplitude increased with increasing secondary turn ratio. Under the conditions of no load, a peak output voltage of 13 kV and a pulse width of 120 ns were obtained with a voltage across the drain–source terminals of the MOSFET of 1 kV. The peak voltage increased, and the peak current and pulse width decreased, with increasing load resistance and decreased capacitance. The maximum energy transfer efficiency was obtained at 500 Ω and was approximately 56%.

Peak oxygen pulse response during maximal cardiopulmonary exercise testing on a treadmill: applicability analysis of the FRIEND registry prediction equation in a Brazilian healthy sample

Abstract Background Peak oxygen uptake (VO2peak), measured by cardiopulmonary exercise test (CPET), is an established variable for prognostic assessment. Other VO2peak-derived variables, such as the peak oxygen pulse (peakO2pulse), also provide valuable information for risk stratification in patients with cardiac diseases. For individualized assessment, the measured peakO2pulse can be compared to reference standards using predictive equations, such as the FRIEND Registry [peakO2pulse = 23.2 – (0.09 × Age) – (6.6 × Sex (female:1; male: 0)]. However, the applicabilty of this equation in a Brazilian population sample has never been evaluated. Purpose To conduct an external validation of the FRIEND registry prediction equation for treadmill peakO2pulse in a sample of healthy Brazilian individuals. Methods Cross-sectional study involving subjects assessed by treadmill CPET in the Brazilian Midwest region from January 2011 to March 2020. Inclusion criteria: healthy individuals aged ≥ 20 years with a peak respiratory exchange ratio ≥ 1.00. Exclusion criteria: history of cardiovascular or pulmonary disease, presence of cardiovascular risk factors (hypertension, diabetes mellitus, current smoking, and obesity), and abnormalities on CPET. Variables were described as median and interquartile range (IQR). Statistical comparisons between measured and predicted values were conducted using the Wilcoxon signed rank test, including the calculation of the median differences and the 95% confidence interval (CI). Furthermore, Bland-Altman agreement analysis was utilized to assess the concordance between measured and estimated values. Results A total of 7,843 CPETs were performed. After applying inclusion and exclusion criteria, 3,544 assessments were included (1,574 females and 1,970 males) aged between 20 to 80 years. In the females, the median and IQR of measured peakO2pulse and predicted values were 10.4 (9.0; 12.1) and 13.1 (12.3; 13.7) ml/beat, respectively. This difference was statistically significant (p &amp;lt; 0.001), with a median difference of 2.54 mL/beat (95% CI: 2.40; 2.69). For males, the measured and predicted values were 17.3 (15.1; 19.7) and 19.7 (19.0; 20.2) ml/beat, respectively. The median difference was statistically significant at 2.26 mL/beat (95% CI: 2.11; 2.46) (p &amp;lt; 0.001) (Figure 1). Bland-Altman agreement analysis indicated a bias of 2.33 mL/beat (95% limits of agreement: -2.17 to 6.83) in females and 2.15 mL/beat (95% limits of agreement: -4.34 to 8.65) in males (Figure 2). Conclusions The study reveals that measured median peakO2pulse values are consistently lower than predicted across both sexes, highlighting a significant bias, which limits the applicability of the FRIEND registry prediction equation in the Brazilian population and underscores the international heterogeneity of the variable. The findings advocate for the development of region-specific reference standards to enhance accuracy in predicting peakO2pulse values.

Effect of Sarcobesity Index and Body Adipose Tissue Variables on Cardiopulmonary Exercise Testing Performance in Colorectal Surgery Setting: A Retrospective Cohort Study.

Aims/Background The prognostic significance of body composition variables has become a popular area of research over the recent years. This study aimed to determine whether adipose tissue variables and sarcobesity index measured by computed tomography (CT) could predict cardiopulmonary exercise testing (CPET) performance and long-term mortality in patients undergoing major colorectal surgery. Methods The Strengthening the Reporting of Cohort Studies in Surgery (STROCSS) statement standards were followed to conduct a retrospective cohort study of consecutive patients who had CPET prior to major colorectal surgery between January 2011 and January 2017. Receiver Operating Characteristic curve analysis was conducted to assess the discriminative performances of adipose tissue variables. The association between CT-derived adipose tissue variables (sarcobesity index, visceral adipose tissue, subcutaneous adipose tissue, and total adipose tissue) and CPET performance and mortality were assessed using regression analyses. Results 457 patients were included. Total adipose tissue evaluated via 2-dimensional (2D) and 3-dimensional (3D) approaches predicted oxygen uptake (V̇O2) Rest, V̇O2 anaerobic threshold (AT), ventilatory equivalents for carbon dioxide (V̇E/V̇CO2) AT, ventilatory equivalents for oxygen (V̇E/V̇O2) AT, V̇O2 peak, exercise time, maximum work, peak metabolic equivalents (METS), peak respiratory rate (RER), and peak oxygen pulse. Sarcobesity index (2D and 3D) predicted V̇O2 Rest, V̇O2 AT, V̇E/V̇CO2 AT, V̇O2 peak, maximum work, peak METS, maximum heart rate, and peak RER. Neither total adipose tissue nor sarcobesity index (2D and 3D) predicted 1-year, 3-year, or 5-year mortality. There was no difference in the discriminative performance of adipose tissue variables in predicting mortality. Conclusion The CPET performance may be predicted by radiologically measured adipose tissue variables and sarcobesity index. However, the prognostic value of the variables may not be significant in this setting.

Cardiac Comorbidity and Exercise Intolerance in Bilateral Lung Transplant Recipients Followed at a Pediatric Center.

Reduced exercise capacity is common in young bilateral lung transplantation (Bi-LTx) recipients, but longer-term data on cardiac comorbidities are limited. We evaluate potential cardiac contributions to long-term exercise intolerance in this population. All Bi-LTx recipients at a single pediatric center, who completed routine clinical post-transplant cardiac assessment, including echocardiogram, cardiac exam, and cardiopulmonary exercise testing (CPET), were included. Cardiac risk factors (CRFs) were assessed by history and laboratory tests. CPET-derived peak and percent-predicted peak myocardial oxygen consumption (VO2 peak, ppVO2 peak) were used to quantitate exercise capacity. Percent-predicted peak oxygen pulse (pp peak O2 pulse) assessed stroke volume. 15 patients (67% M; median age 21.6years, median follow-up from Bi-LTx 7.0years) were included. Almost all patients (14, 93%) had multiple CRFs; hypertension and hyperlipidemia/dyslipidemia were the most common. On CPET, 93% (n = 14) had abnormal (≤ 85%) ppVO2 peak (median 59%). 73% (n = 11) had abnormal pp peak O2 pulse (median 74%). Ten had blunted heart rate response to exercise. Nine had left ventricular diastolic dysfunction (LV-DD) on echocardiogram. Median percent-predicted forced expiratory volume in one second was 70%. One had severe chronic lung allograft dysfunction. Cardiac risk factors and exercise intolerance are common among young Bi-LTx recipients years post-transplant, even among those without significant pulmonary dysfunction. High prevalence of multiple CRFs, LV-DD, chronotropic dysfunction, and abnormal stroke volume suggest cardiac comorbidities may contribute to intolerance. Medical management of CRFs and tailored exercise may decrease cardiac risk and improve functional capacity for Bi-LTx survivors.

Dynamic tunability of NIR absorption in a plasmonic grating through nonlinear kerr-effect of graphene-oxide and photothermal phase transition of GSST

In this paper, we present an in-depth examination of the absorption dynamics of a silver plasmonic grating incorporating Kerr-type nonlinear graphene-oxide (GO) nanoslits and a Ge2Sb2Se4Te1 (GSST) phase-change material, both in linear and nonlinear regimes. Linear absorption approaches unity at the resonant wavelength when GSST is amorphous. Upon exposure to a nanosecond Gaussian pulse laser irradiation with appropriate fluences, the amorphous GSST partially crystallizes through a thermoplasmonic-induced process, resulting in a significant reduction of the linear on-resonance absorption in the form of a step-like curve. Additionally, the weak off-resonance linear absorption of the system can be enhanced owing to the non-uniform phase-transition within the GSST. Transitioning to a nonlinear regime, considering the third-order nonlinearity of GO nanoslits, reveals distinct absorption behaviors. Temporal analysis reveals that at the on-resonance wavelength, the unit absorption decreases with increasing laser intensity, reaching a minimum at the pulse peak due to the Kerr nonlinearity in the GO. Intriguingly, the absorption exhibits a U-shaped curve at lower fluences, while at higher fluences, it stabilizes at a lower value post-pulse peak where the amorphous GSST undergoes a thermally driven partially crystallization phase transformation. In the off-resonance mode, the weak absorption enhances dramatically by increasing the fluence, tracing an imperfect parabolic trajectory that reaches nearly unit at the trailing edge of the pulse, attributed to the Kerr nonlinearity within the GO nanoslits. By further increasing the laser fluence, the photothermal response of the GSST emerges as the dominant factor, diminishing the unity absorption observed at the trailing edge of the pulse. These findings underscore the dynamic responsiveness of the proposed grating to pulsed laser illumination, driven by the nonlinear Kerr effect and GSST reconfigurability, offering promising opportunities for developing active optical switching devices.

Strain detection based on magnetic domain wall motion in amorphous FeSiBNb thin film

The strain dependence of the pulse voltage induced in a pickup coil originating from the domain wall motion in an amorphous FeSiBNb thin film was investigated. No significant change in the peak pulse voltage was observed when tensile strain was applied to the thin film, whereas the peak pulse voltage changed steeply when compressive strain was applied. In addition, strain susceptibility could be controlled via appropriate annealing. Evaluation of the strain gauge comprising the amorphous FeSiBNb thin film, a pickup coil, an electrical circuit (which converts the pulse voltage into direct current voltage), and a Helmholtz coil revealed that strain gauge has a notably high gauge factor of approximately 37,500.

A probability density functions convolution based analytical detection probability model for LiDAR with pulse peak discriminator

Detection probability as a key indicator of LiDAR determines the quality of 3D images. To explore the detection essence of pulse LiDAR, a probability density function (PDF) convolution based analytical detection probability model is established to predict the detection performance of pulse LiDAR with peak discriminator. In the model, the analytical detection probability is determined by convoluting the PDFs of echo pulse point and the maximum noise amplitude derived from the cumulative multiplication of the PDFs of all noise points. Experiments showed that the theoretical probabilities calculated from model is consistent with the experimental results. Based on the model, a detection threshold of peak discriminator is set to 4.5 times noise standard deviation for achieving a detection probability of 90 %@14.6 dB and a false alarm probability of 0.17 %, which is verified using the lab-built LiDAR. The presented model offers valuable guidance for system design and detection parameter selection.