Threshold Peak Research Articles

Microstructure-Based Computational Analysis of Deformation Stages of Rock-like Sandy-Cement Samples in Uniaxial Compression

This work presents a new finite-difference continuum damage mechanics approach for assessment of threshold stresses based on the mechanical response of a representative volume element of a sandy-cement rock-like material. An original experimental study allows validating the mathematical model. A new modification of the damage accumulation kinetic equation is proposed. Several approaches based on acoustic emission, instantaneous Poisson's ratio and reversal point method are employed to determine the threshold stresses. Relying on the numerical modeling of deformation and failure of model samples, the threshold stresses and the deformation stages are determined. The model predicts the crack initiation stress threshold with less than 10% error. The model prediction of the crack damage stress threshold corresponds to the upper boundary of the experimental range. The model predicts the peak stress threshold with less than 0.2% error in comparison with the average experimental peak stress. The results of numerical modeling are shown to correlate well with the available experimental and literature data and sufficiently complement them.

Myocardial efficiency index in patients with heart disease after a cardiac rehabilitation program.

The myocardial efficiency index (MEI) correlates the Myocardial Oxygen Consumption (MVO2) with the Maximum Oxygen Consumption (VO2max), this index provides information about the cardiovascular efficiency (CVEf). In athletes, the MEI improves after a micro-cycle training, however in patients with cardiovascular disease undergoing Cardiac Rehabilitation Program (CRP), IEM behavior could be a good estimator related to the improvement training period. The objective of this study was to determine the myocardial efficiency index behavior in patients with heart disease and high cardiovascular risk (HCVR) after a CRP. Ambilective, descriptive, analytical, non-randomized cohort study was conducted. Patients with heart disease of mixed etiology and HCVR admitted to a CRP for 4-6 weeks were selected. All patients performed a maximal exercise test in band before and after the CPR. Thresholds of VO2 peak, METs-load, Double product (DP) and MEI were determined. A cut-off point for the MEI was established using a ROC curve with a value of 7.37, area under the curve: 0.68 (95% CI 0.61 - 0.76, p < 0.001), sensitivity 0.60 and 1-specificity 0.35. 193 patients with a mean age of 62.3 years were included, predominantly men (66.2%). Percentages changes in the MEI-27.1% (p < 0.001),METs-43.1% (p < 0.001),DP 5.7% (p < 0.01), and MVO2: 8.3% (p < 0.01) were observed at the end of CRP. Significant change in the MEI were observed after CRP associated to CVEf improvement, suggesting that this parameter could be considered as a good clinical tool in the CRP care programs.

A Search for Predicted Astrometric Microlensing Events by Nearby Brown Dwarfs* *Released.

Gravitational microlensing has the potential to provide direct gravitational masses of single, free-floating brown dwarfs, independent of evolutionary and atmospheric models. The proper motions and parallaxes of nearby brown dwarfs can be used to predict close future alignments with distant background stars that cause a microlensing event. Targeted astrometric follow up of the predicted microlensing events permits the brown dwarf’s mass to be measured. Predicted microlensing events are typically found via searching for a peak threshold signal using an estimate of the lens mass. We develop a novel method that finds predicted events that instead will lead to a target lens-mass precision. The main advantage of our method is that it does not require a lens-mass estimate. We use this method to search for predicted astrometric microlensing events occurring between 2014 and 2032 using a catalog of 1225 low-mass star and brown-dwarf lenses in the Solar Neighborhood of spectral type M6 or later and a background source catalog from DECaLS Data Release 9. The background source catalog extends to g = 23.95, providing a more dense catalog compared to Gaia. Our search did not reveal any upcoming microlensing events. We estimate the rate of astrometric microlensing event for brown dwarfs in the Legacy Survey and find it to be low ∼10−5 yr−1. We recommend carrying out targeted searches for brown dwarfs in front of the Galactic Bulge and Plane to find astrometric microlensing events that will allow the masses of single, free-floating brown dwarfs to be measured.

An update on the seismic categorization for seismic risk assessment of existing Canadian buildings

An investigation has been done to update key input parameters in the recent seismic-risk-screening tools developed by the National Research Council Canada for the six seismic categories. In this study, the seismic categorization system in the recent seismic-risk-screening tools of the National Research Council Canada is extended to include Canadian buildings abroad by including threshold peak ground acceleration values, a more global set of modified Mercalli intensity, peak ground acceleration, and spectral response acceleration and peak ground acceleration relationships. The relationships among spectral response acceleration, peak ground acceleration, and peak ground velocity values have been derived using least-squares regression analyses to obtain the threshold values of both peak values associated with various modified Mercalli intensity values for each seismic category. Based on the updated relationships, the seismic categorization system is applied to 679 locations in Canada and 226 locations outside Canada.

Coronary stenosis is a risk marker for impaired cardiac function on cardiopulmonary exercise test

BackgroundCardiac function varies in different ways in ischemic heart disease (IHD). We aimed to evaluate the characteristics of cardiac function on cardiopulmonary exercise test (CPET) in IHD with different coronary stenoses.MethodsTotally 614 patients with IHD were divided into non-obstructive coronary artery disease (NOCAD) (stenosis < 50%), obstructive coronary artery disease (OCAD) (stenosis 50-90%) and severe OCAD ( stenosis > 90%) according to the coronary angiography. And 101 healthy volunteers as controls. All participants performed CPET to assess cardiac function by oxygen uptake (VO2), estimated cardiac output (CO), and heart rate (HR).ResultsGenerally, the values of VO2, CO, and HR in IHD were significantly lower than in healthy volunteers. Among 289 NOCAD, 132 OCAD, and 193 severe OCAD, significantly decreased values of VO2, CO, HR were observed (VO2 peak: 16.01 ± 4.11 vs. 15.66 ± 4.14 vs. 13.33 ± 3.4 mL/min/kg; CO: 6.96 ± 2.34 vs. 6.87 ± 2.37 vs. 6.05 ± 1.79 L/min; HR: 126.44 ± 20.53 vs. 115.15 ± 18.78 vs. 109.07 ± 16.23 bpm, P < 0.05). NOCAD had significantly lower VO2 at anaerobic threshold (-1.35, 95%CI -2.16 - -0.54) and VO2 peak (-2.05, 95%CI -3.18 - -0.93) compared with healthy volunteers after adjustment. All IHD patients were associated with low stroke volume and inefficient gas exchange (P < 0.05).ConclusionIHD with increasing atherosclerotic burdens were associated with impaired cardiac output and chronotropic response on CPET. NOCAD should be given more early prevention and rigorous follow-up.

IMPROVEMENT OF PEDESTRIAN DEAD RECKONING ALGORITHM FOR INDOOR POSITIONING BY USING STEP LENGTH ESTIMATION

Abstract. Pedestrian dead reckoning (PDR) can solve the position information by its inertial measurement unit (IMU), which is a method to achieve indoor autonomous positioning without deploying positioning base stations in advance. However, affected by the accumulated error, the positioning accuracy will decrease with the increase of the moving distance. To improve the indoor positioning accuracy, the step length estimation of PDR is improved. A PDR method combining the information on walking frequency, acceleration variance, and fixed step is proposed. Firstly, the pedestrian's walking steps are detected and estimated by the threshold peak method; secondly, the step frequency and acceleration variance are calculated, and the step length estimation model is fitted with the fixed step length of the pedestrian to estimate the step length of each step; then, the fusion algorithm of magnetometer, accelerometer, and gyroscope are used to estimate the heading; finally, combined with the step number, step length, and heading angle, the position information of walking is calculated by dead reckoning. The experimental results show that in the practical distance of 42.6 m, the accuracy of dead reckoning distance based on the combination of step frequency, acceleration variance, and fixed step length can reach 98.47%, which is better than the fixed step length and linear step length version, 5.09% higher than the linear step length and 0.35% higher than the fixed step length version.

Convolutional neural networks for ultrasound corrosion profile time series regression

A customised convolutional neural network (CNN) architecture is proposed in this paper to make estimations about the thickness values (minimum and mean) of corroded profiles from an ultrasonic time-series measurement (A-scan). The CNN architecture is determined after a hyper-parameter optimisation which leads to the best performing network. The model is trained using synthetic data and tested on both synthetic and experimental datasets. A comparison is made with (1) a state-of-the-art network for time series analysis and (2) conventional thickness estimation techniques such as peak envelope and threshold crossing. The proposed network provides an accurate estimation of the thickness values and outperforms the conventional techniques in both synthetic and experimental datasets. When compared to a conventional threshold-crossing technique for minimum thickness prediction, the proposed network is more consistent and less sensitive to changes in the threshold.

An innovative cardiac rehabilitation based on the power-force-velocity profile to further improve cardiorespiratory capacities in coronary artery disease patients

Abstract Background Several studies have shown the importance of the relationship between the power-force-velocity profile (PFVP) and sport performance in elite athletes through optimised exercise training [1]. Optimising the training programme is constantly sought in rehabilitation among patients always younger with coronary artery disease. To adapt the exercise training to each patient, we rely mainly on the results of the cardiopulmonary exercise test [2]. However, the nature of the training is the same for all patients. We hypothesized that the assessment of the PFVP at the beginning of the cardiac rehabilitation (CR) would allow to better adapt the CR training programme for each patient. Purpose The aim of this study was to compare the effects of two exercise training programmes: a traditional CR versus a new CR relied on patient's PFVP on cardiorespiratory system and functional capacities in coronary patients. Methods This prospective randomized controlled trial was conducted from May 2020 to July 2021. A total of 89 patients were randomly assigned (1:1) to test or control group. Before starting CR, participants performed two sprints of 8 s on a cycle ergometer to define the PFVP. The PFVP was analysed to determine whether the participant had a force or velocity deficit. Patients included in test group followed a specific cycling training programme based on their weak point (i.e., specific force training with high resistance and low pedalling frequency on the cycle if the PFVP was oriented in velocity and reversely). While control patients attended a conventional CR programme. The 3-week training intervention consisted of 40 min of cycling, 30 min of walking on treadmill and 20 min of strength training (4/week). Cardiopulmonary exercise test (VO2 at the first ventilatory threshold, SV1 and VO2 peak in ml/min/kg), functional assessments (distance of 6-min walk test, handgrip strength, 10 sit-to-stand repetitions, cholesterol levels, LDL-C and quality of life) were performed at the baseline and after CR. A two-way ANOVA with one repeated measure (pre vs. post) and one independent factor (test vs. control) was realized. Results The mean age was 61.0±9.6 years, 18% were women. A significant difference was observed in VO2 peak (test: +22.0±19.1% vs. control: +10.2±15.8%, p=0.003) and VO2 SV1 (test: +35.9±33.9% vs. control: +11.9±34.4%, p&amp;lt;0.001), LDL-C (p=0.016) and quality of life (p&amp;lt;0.001). No significant change between groups in other functional tests occurred after CR programme. Conclusion Cardiopulmonary activity, cholesterol and quality of life were improved after 3-week exercise programme. The novel CR depending on initial PFVP showed greater cardiorespiratory benefits than a conventional CR. Therefore, the PFVP can be used in CR to adapt specifically the content of training sessions. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): DRCI University Hospital Saint-Etienne

Three-dimensional grain-based model study on triaxial mechanical behavior and fracturing mechanism of granite containing a single fissure

In order to investigate the mechanical behavior and failure mechanism of fissured granite under triaxial compression, a three-dimensional grain-based model (GBM3D) was established in particle flow code (PFC) for simulating the triaxial compression of granite specimens with various fissure inclinations (α = 0°, 30°, 45°, 60° and 90°) under different confining pressures (0, 5, 10 and 20 MPa). First, a group of micro-parameters used in GBM3D was calibrated based on the experimental triaxial compression results of intact specimens, the simulation results of fissured specimens based on these parameters are in good agreement with the experimental results. Compared with intact granite, the fissured granite has smaller peak strength, crack damage threshold, elastic modulus and axial peak strain. Confining pressure can improve the mechanical properties of granite at the same fissure angle, and under the same confining pressure, the mechanical properties increase with the increase of fracture angle. With the increase of axial stress, the cracks first emerge from the crack apices and propagate toward the ends of the specimen along the direction of the principal stress, and the cracks penetrate each other and eventually lead to the failure of the specimens. The displacement field shows that the main cracks are all generated at the interfacial locations where large relative displacements occur between the particles. The three-dimensional spatial crack distribution characteristics of the damaged specimens are not only influenced by the confining pressure, but also related to the fissure angle. The confining pressure not only complicates the crack distribution characteristics, but also increases the total count of cracks. As the fissure angle increases, anti-tensile wing crack is more likely to appear in the specimen.

An allopurinol adherence tool using plasma oxypurinol concentrations.

This study aimed to develop and evaluate an allopurinol adherence tool based on steady-state oxypurinol plasma concentrations, allopurinol's active metabolite. Plasma oxypurinol concentrations were simulated stochastically from an oxypurinol pharmacokinetic model for allopurinol doses of 100-800 mg daily, accounting for differences in renal function, diuretic use and ethnicity. For each scenario, the 20th percentile for peak and trough concentrations defined the adherence threshold, below which imperfect adherence was assumed. Predictive performance was evaluated using both simulated low adherence and against data from 146 individuals with paired oxypurinol plasma concentrations and adherence measures. Sensitivity and specificity (S&S), negative and positive predictive values (NPV, PPV) and receiver operating characteristic (ROC) area under the curve (AUC) were determined. The predictive performance of the tool was evaluated using adherence data from an external study (CKD-FIX). The allopurinol adherence tool produced S&S values for trough thresholds of 89-98% and 76-84%, respectively, and 90%-98% and 76-83% for peak thresholds. PPV and NPV were 79-84% and 88-94%, respectively, for trough and 80-85% and 89-98%, respectively, for peak concentrations. The ROC AUC values ranged from 0.84 to 0.88 and from 0.86 to 0.89 for trough and peak concentrations, respectively. S&S values for the external evaluation were found to be 75.8% and 86.5%, respectively, producing an ROC AUC of 0.8113. A tool to identify people with gout who require additional support to maintain adherence using plasma oxypurinol concentrations was developed and evaluated. The predictive performance of the tool is suitable for adherence screening in clinical trials and may have utility in some clinical practice settings.

INPPTR: An improved retracking algorithm for inland water levels estimation using Cryosat-2 SARin data

As an important technology for measuring water levels, satellite altimetry has been widely using in the lake, river, and wetland in the past two decades. However, the waveform pollution limits its application in areas with complex topography, the accuracy of the existing retracking algorithms need to be further improved. In this study, a new retracking algorithm, named Improved Narrow Primary Peak Threshold Retracking algorithm (INPPTR), based on Narrow Primary Peak Threshold Retracking algorithm (NPPTR) is presented. This retracking algorithm eliminates the noise in the waveform, extracts more accurate main peaks of the waveform, and performs Gaussian fitting on the main peaks with serious waveform pollution. Finally, the more stable water levels in areas with complex terrain can be obtained from Cryosat-2 Synthetic Aperture Radar Interferometer (SARin) waveform. To verify the accuracy of retracking algorithms, the water level time series of eight lakes and one river were retrieved using INPPTR and other three retracking algorithms (NPPTR, NPPOR and MWaPP), then were compared to the in-situ data. For Qinghai Lake, Namco Lake, Selin Lake, Zhair Namco Lake, Issyk Lake, Great Salt Lake, Tahoe Lake and Great Slave Lake, where SARin mode is used, and the root mean squared errors (RMSE) obtained by INPPTR are 18.09 cm, 21.69 cm, 20.48 cm, 34.82 cm, 17.39 cm, 39.68 cm, 26.25 cm and 18.43 cm, respectively. Compared with NPPTR, the RMSE of INPPTR is reduced by 9.91 %, 14.83 %, 7.62 %, 14.74 %, 6.70 %, 4.11 %, 105.37 % and 25.02 %, respectively. For the Amazon River, the RMSE of INPPTR is 58.24 cm, compared with the other three retracking algorithms, the RMSE obtained by INPPTR is the lowest as well. In summary, the accuracy of INPPTR is significantly higher than the other three retracking algorithms, and INPPTR can process Cryosat-2 SARin data effectively and provide more stable and effective water levels, laying the foundation for long-term, high-accuracy water levels monitoring of inland water bodies with complex terrain.

Noise analysis of MoTe2-based dual-cavity MOSFET as a pH sensor

Field-effect transistor (FET) pH sensors have been studied for a long time because of their low cost, sound sensitivity, and high operational speed. Recently, transition metal dichalcogenides (TMD) materials such as MoTe2, MoS2, among others, have emerged as promising channel materials for developing energy-efficient electronic devices. TMD-based sensors have shown excellent results because of the high surface area–volume ratio and better bio-specific interaction. This paper proposes and analyzes a MoTe2 channel–based dual-cavity (DC) accumulation metal oxide semiconductor field effect transistor (MOSFET) as a pH sensor. For a comprehensive study, a pH-FET noise model has been considered to investigate the amount of noise associated with the proposed FET under various ionic concentrations and device dimensions. The electrolytic semiconductor has been modeled based on ion dynamics for the simulation study. A site-binding model has been incorporated to capture the surface charge density fluctuations at the interface of electrolyte and gate oxide for different pH values. The effect of gate length scaling on the device performance is studied to comprehend its scalability. With this MoTe2-based DC accumulation MOSFET sensor, a peak threshold sensitivity of 77 mV pH−1 has been achieved. To provide a comparative performance analysis of the proposed work, a benchmarking figure is included and a detailed fabrication methodology is also presented in this paper. All simulations are performed with an experimentally calibrated setup in SILVACO Technology Computer Aided Design (TCAD).

Smartphone-Based Unconstrained Step Detection Fusing a Variable Sliding Window and an Adaptive Threshold

Step detection for smartphones plays an important role in the pedestrian dead reckoning (PDR) for indoor positioning. Aiming at the problem of low step detection accuracy of smartphones in complex unconstrained states in PDR, smartphone-based unconstrained step detection method fusing a variable sliding window and an adaptive threshold is proposed. In this method, the dynamic updating algorithm of a peak threshold is developed, and the minimum peak value filtered after a sliding window filter is used as the adaptive peak threshold, which solves the problem that the peak threshold of different motion states is difficult to update adaptively. Then, a variable sliding window collaborative time threshold method is proposed, which solves the problem that the adjacent windows cannot be contacted, and the initial peak and the end peak are difficult to accurately identify. To evaluate the performance of the proposed unconstrained step detection algorithm, 50 experiments in constrained and unconstrained states are conducted by 25 volunteers holding 21 different types of smartphones. Experimental results show: The average step counting accuracy of the proposed unconstrained step detection algorithm is over 98%. Compared with the open source program Stepcount, the average step counting accuracy of the proposed algorithm is improved by 10.0%. The smartphone-based unconstrained step detection fusing a variable sliding window and an adaptive threshold has a strong ability to adapt to complex unconstrained states, and the average step counting accuracy rate is only 0.6% lower than that of constrained states. This algorithm has a wide audience and is friendly for different genders and smartphones with different prices.

P295 EXERCISE OXYGEN KINETIC IN HYPERTROPHIC CARDIOMYOPATHY: RESULTS FROM A MULTICENTER CARDIOPULMONARY EXERCISE TESTING STUDY

Abstract Aims Reduced cardiac output (CO) has been considered crucial in symptoms’ genesis in hypertrophic cardiomyopathy (HCM). We evaluated the cardiopulmonary exercise testing (CPET) response in HCM focusing on parameters strongly associated with stroke volume (SV) and cardiac output (CO), such as oxygen uptake (VO2) and O2–pulse, considering both their absolute values and temporal behavior during physical exercise. Methods and Results We enrolled 312 non–end stage HCM patients, divided according to left ventricle outflow tract obstruction (LVOTO) at rest or during Valsalva maneuver (72% with LVOTO&amp;lt;30; 10% between 30 and 49 and 18% ≥ 50mmHg). Peak VO2 (percent of predicted), O2–pulse and ventilation to carbon dioxide production (VE/VCO2) slope did not change across LVOTO groups. Ninety–six (31%) HCM patients presented an abnormal O2–pulse temporal behavior, irrespective of LVOTO values. These patients showed lower peak systolic pressure, workload (106±45 vs. 130±49W), VO2 (74±17 vs. 80±20%) and O2–pulse (12 [9–14] vs. 14 [11–17]ml/beat), with higher VE/VCO2 slope (28 [25–31] vs. 27 [24–31]) (p &amp;lt; 0.005 for all). Only 2 patients had an abnormal VO2/work slope. Conclusion None of CPET parameters, either as absolute values or dynamic relationships, were associated with LVOTO. Differently, an abnormal O2–pulse exercise behavior, which is strongly related to inadequate SV during exercise, correlates with reduced functional capacity (peak and anaerobic threshold VO2 and workload) and increased VE/VCO2 slope, helping identifying more advanced disease irrespectively of LVOTO. Adding O2–pulse kinetics evaluation to standard CPET could lead to a potential incremental benefit in terms of HCM prognostic stratification and, then, therapeutic management.

An innovative cardiac rehabilitation based on the power-force-velocity profile to further improve cardiorespiratory capacities in coronary artery disease patients

Abstract Funding Acknowledgements Type of funding sources: Other. Main funding source(s): Doctoral contract 2018-2022 Background Several studies have shown the importance of the relationship between the power-force-velocity profile (PFVP) and sport performance in elite athletes through optimised exercise training.[1] Optimising the training programme is constantly sought in rehabilitation among patients always younger with coronary artery disease. Nowadays, it is well established that intermittent training should be offered to coronary patients during the rehabilitation cycle.[2] In this continuity, the assessment of the PFVP at the beginning of the cardiac rehabilitation (CR) would allow to better adapt the CR training programme for each patient. Purpose The aim of this study was to compare the effects of two exercise training programmes: a traditional CR versus a new CR relied on patient’s PFVP on cardiorespiratory, functional and autonomic systems in coronary patients. Methods This prospective randomized controlled trial was conducted from May 2020 to July 2021 in an university hospital. A total of 89 patients were randomly assigned (1:1) to test or control group. Before starting CR, participants performed two sprints of 8 s on a cycle ergometer to define the PFVP. The PFVP was analysed to determine whether the participant had a force or velocity deficit. Patients included in test group followed a specific cycling training programme based on their weak point (i.e., specific force training with high resistance and low pedalling frequency on the cycle if the PFVP was oriented in velocity and reversely). While control patients attended a conventional CR programme. The 3-week training intervention consisted of 40 min of cycling, 30 min of walking on treadmill and 20 min of strength training (4/week). Cardiopulmonary exercise test (VO2 at the first ventilatory threshold, SV1 and VO2 peak in ml/min/kg), functional assessments (distance of 6-min walk test, handgrip strength, 10 sit-to-stand repetitions, cholesterol levels, LDL-C and quality of life) and autonomic nervous system (heart rate variability and sensitivity baroreflex) were performed at the baseline and after CR. A two-way ANOVA with one repeated measure (pre vs. post) and one independent factor (test vs. control) was realized. Results The mean age was 61.0 ± 9.6 years, 18% were women. A significant difference was observed in VO2 peak (test: +22.0 ± 19.1% vs. control: +10.2 ± 15.8%, p=0.003) and VO2 SV1 (test: +35.9 ± 33.9% vs. control: +11.9 ± 34.4%, p&amp;lt;0.001), LDL-C (p=0.016) and quality of life (p&amp;lt;0.001). No significant change between groups in other functional tests and autonomic activity occurred after CR programme. Conclusion Cardiopulmonary activity, cholesterol and quality of life were improved after 3-week exercise programme. The novel CR depending on initial PFVP showed greater cardiorespiratory benefits than a conventional CR. Therefore, the PFVP can be used in CR to adapt specifically the content of training sessions.

19: CARDIOPULMONARY FUNCTION FOLLOWING NEO-ADJUVANT CHEMOTHERAPY FOR OESOPHAGO-GASTRIC ADENOCARCINOMA

Abstract Background and aim The role of perioperative chemotherapy in oesophago-gastric adenocarcinoma is well established. Epirubicin, Cisplatin/Oxaliplatin and Capecitabine (ECX/EOX) based regimens have recently been challenged by Fluoruracil, Leucovorin, Oxaliplatin and Docetaxel (FLOT). We aimed to assess whether these regimens had variable effects on patient cardiopulmonary fitness and subsequent suitability for major surgery following treatment. Methods Cardiopulmonary exercise (CPEX) testing was used to provide objective estimation of cardiopulmonary function metrics including peak oxygen consumption (VO₂ max), anaerobic threshold (AT) and ventilatory efficiency (VeVCO₂ slope). Paired CPEX testing was performed in participants undergoing treatment for oesophago-gastric adenocarcinoma pre and post FLOT (n = 26) or ECX/EOX (n = 51) chemotherapy regimens, as selected by the multidisciplinary team. Univariate non-parametric testing was used to assess differences for significance. Results Participants undergoing FLOT were younger [median (IQR): 61(12.5) □□. 69(11) years, P = 0.003] and had a higher pre-chemotherapy VO₂ max/m2 [929(231) □□. 838(198) ml/m2/min, P = 0.040] and FEV1 [3.5(0.8) □□. 2.9(0.6), P = 0.017] compared to those undergoing ECX/EOX. Other metrics including BMI, weight, VO₂ max/kg, AT, VeVCO₂ slope, FVC and FEV1 were not significantly different at baseline. There was no difference in time to CPEX testing after completing chemotherapy treatment [median 27 □□. 27 days]. Both FLOT and ECX/EOX significantly reduced VO₂ max/kg [−2.85(4.0) &amp; -1.70(3.5) ml/kg/min], VO₂ max/m2 [−101(193) &amp; -68(155) ml/m2/min] and AT [−1.35(2.7) &amp; -1.1(2.3) ml/kg/min] respectively (all P &amp;lt; 0.001), with no significant absolute or proportional differences found between the groups. Respiratory function was not altered. Conclusion A reduction in cardiopulmonary function should be accounted for when planning surgery for oesophago-gastric cancer following neo-adjuvant chemotherapy. We did not find significant differences in cardiopulmonary function reduction between chemotherapy regimens in this cohort. However, there was a trend towards a greater reduction in cardiopulmonary function after FLOT and studies in larger cohorts of patients are needed to clarify this.

A semi-empirical model for peak temperature estimation in friction stir welding of aluminium alloys

Process parameters and base material thermal properties strongly affect peak temperature evolution in friction stir welding (FSW). This work develops a semi-empirical model for peak temperature estimation during FSW of aluminium alloys. Several bead-on-plate runs were conducted on AA5083-H111, AA6082-T6 and AA7075-T6. Different rotational and welding speeds were tested while measuring the temperature with a thermocouple embedded in the tool. A polynomial model was proposed with the model's coefficients strongly correlating to the material thermal properties. Additionally, a threshold peak temperature was defined to avoid cold defects by combining temperature measurements with joint quality information obtained from X-ray scans. The efficiency of the model and the defined threshold are proven by applying them to the literature.

Damage integral and other predictive formulas for nonisothermal heating during laser exposure.

.Significance: Physics-based models supply simulated temperature rises to photothermal damage rate models and provide comprehensive risk assessments for laser-induced damage. As the physics-based models continue to be refined, the damage rate models have not advanced. This peculiar lack of improvement is counterintuitive considering the damage integral (), originally derived for isothermal heating events, and fails to accurately represent the nonisothermal heating from short laser exposures.Aim: Derive a nonisothermal form of the damage integral and predict more accurately the damage induced by short laser exposures, as well as identify the role of heating rate in laser damage.Approach: From first principles, we derived a version of the damage integral specific to the shape of thermal profiles rather than the square function provided by Arrhenius plots. We used previously published threshold thermal profiles, where all nonisothermal frequency factors () solved all values to unity. Nonisothermal correction factors correct isothermal values.Results: The values were identical for both the isothermal and nonisothermal conventions. Correction factor values for ranged from 0.0 (20-s exposures at thermal steady state) to (0.05-s exposures). Based on empirical results, we have derived a two-dimensional empirical formula that predicts the heating rate as a function of exposure duration and ambient temperature. Threshold peak temperatures () and threshold critical temperatures are mathematically determined without thermal profiles when appropriate and values are established.Conclusions: We have identified a modified damage integral that does not rely on the Arrhenius plot and provides a value for the frequency factor () that accounts for the nonisothermal nature of short laser exposures. The method, validated in our in vitro retinal model, requires thermal profiles recorded under threshold conditions, such as at minimum visible lesions or the boundary of cell death. The method is a new option for laser damage modelers.

GÜÇ FAKTÖRÜ VE FLICKERI DİKKATE ALAN BİR TEPE AKIM MODU KONTROLLÜ SEPİC LED SÜRÜCÜ TASARIMI

In this paper, a peak current mode controlled single ended primary inductor converter (SEPIC) LED driver is proposed to control the brightness of the LED. One string of 37 series connected LEDs is adopted as output of the circuit. The proposed control strategy is based on measuring MOSFET peak current value using a shunt resistor. When this voltage reaches peak threshold value, controller turns off MOSFET. The output current is adjusted to desired levels by changing this peak threshold value. The power factor in the AC power supply side is low because of the full wave bridge rectifier with capacitor filter at the input of the converter. The proposed control strategy is applied with power factor correction (PFC) circuit where input voltage is multiplied by control voltage to achieve high power factor. In PFC circuit, although the line current waveform is slightly distorted due to voltage limitations in integrated circuit (IC) chip used for the proposed control strategy, power factor is kept above 0.9 for operation region between 100mA-300mA. In addition, flicker on LED string is measured for operating current region and flicker limits are revealed. Adjustable output current levels, low flicker on LED string, MOSFET peak current control at each cycle, fast output dynamics, and high power factor are acquired by the proposed control strategy.

Exercise oxygen pulse kinetics in patients with hypertrophic cardiomyopathy

ObjectivesReduced cardiac output (CO) has been considered crucial in symptoms’ genesis in hypertrophic cardiomyopathy (HCM). Absolute value and temporal behaviour of O2-pulse (oxygen uptake/heart rate (VO2/HR)), and the VO2/work relationship...