Time Delay Research Articles

Does regionalization of initial breast cancer care delay time to surgery?

By leveraging a natural experiment afforded by New York's 2009 policy restricting Medicaid reimbursement for breast cancer surgery at low-volume hospitals, this study examined the effect of regionalization on time from breast cancer diagnosis to initial upfront surgery. By using a linked data set merging New York Cancer Registry and New York facilities' discharge data, women with stage I-III incident breast cancer during the pre- (2004-2008) and postpolicy (2010-2013) periods were identified. Multivariable difference-in-difference-in-differences models estimated the policy effect on the probability of experiencing delayed care (>60 days) between diagnosis and initial surgery. Among 71,135 women, 12% had Medicaid coverage. Women treated in postpolicy years (p<.001 relative to prepolicy) and Medicaid beneficiaries (p<.001 relative to non-Medicaid patients) were more likely to experience delayed care. Non-Medicaid beneficiaries had a 12.6% probability of delayed care postpolicy (compared to 8.8% prepolicy), whereas Medicaid beneficiaries had a 21% probability of delayed care postpolicy (compared to 14.5% prepolicy). Although these increases were not statistically different between the Medicaid and non-Medicaid groups as a whole, which indicates no overall policy effect, Medicaid beneficiaries in nonurban areas were more likely to experience delayed care after the policy implementation (p=.04). Regionalization of breast cancer care in New York did not lead to a significant overall decrease in access to timely surgical care. Regionalization of care may be a promising approach to improving breast cancer outcomes. However, the potential impact on nonurban and other vulnerable populations must be carefully considered to prevent exacerbating disparities in access to care.

Carotid pulse wave velocity estimation based on incident waves using coherent plane wave compounding ultrasound

Objective. Local pulse wave velocity (PWV) plays a crucial role in assessing the regional arterial elasticity. Accurate estimation of local PWV is beneficial for the risk assessment and early diagnosis of cardiovascular diseases. In this study, a method involving incident waves based on coherent plane wave compounding ultrasound (IWCU) is proposed to suppress reflected waves in pulse waves (PW) and improve the performance of transit time (TT)-based local PWV estimation.Approach. The ultrasonic radio frequency echo signals are collected and coherently compounded, and the PWs and central blood flow velocities at 128 beam positions are calculated, from which the incident waves (IWs) are estimated based on the Kelvin-Voigt model. Then, the time delays (TDs) of the IWs propagating are calculated, and the local PWV is finally estimated. The mean and standard deviations (MSD) of the normalized root mean squared errors NRMSEs between the presupposed and estimated TDs and PWVs were calculated for quantitatively evaluating the performance of the proposed IWCU method, and compared with those of the PWs based on coherent plane wave compounding ultrasound and the regional upstroke tracking methods in simulation experiments. The relative errors, Bland-Altman analysis and coefficient of variation (CV) were measured to further assess the accuracy, reproducibility and variability of IWCU method inin vitroandin vivoexperiments.Main results. The IWCU method yields higher accuracy, reproducibility and lower variability for local PWV estimation. The MSD of the NRMSEs for TDs and local PWVs are 11.78 ± 0.52% and 4.10 ± 2.25%. Additionally, the mean relative error and CV are 6.10% and 12.56%, respectively.Significance. The IWCU method provides improved TT-based local PWV estimation, and has the potential to support future clinical diagnoses of arterial stiffness.

Optimising CT Perfusion (CTP) in Posterior circulation infarction (POCI): A comprehensive analysis of CTP postprocessing algorithms for POCI.

CTP Software packages utilise various mathematical techniques to transform source data into clinically useful maps. These techniques have not been validated for Posterior circulation infarction (POCI). Studies of anterior circulation stroke have shown that algorithm differences significantly influence the accuracy and best tissue parameters and thresholds of output maps. We examined the influence of the processing algorithm on CTP accuracy and best tissue parameters and thresholds in acute POCI. Data were analysed from patients diagnosed with a POCI enrolled in the International-stroke-perfusionimaging-registry (INSPIRE). Fifty-eight-patients with baseline multimodal-CT with occlusion of a large posterior-circulation artery and follow up diffusion-weighted-MRI at 24-48 hours were included. CTP parametric maps were generated using five algorithms; Singular value deconvolution, Singular value deconvolution with delay and dispersion correction (SVDd), Partial-deconvolution, Stroke-stenosis and Maximum Slope models. Receiver operating curve (ROC) analysis and linear regression were used for voxel-based analysis and volume-based analysis respectively. Partial-deconvolution using the Mean Transit Time (MTT) parameter was the optimal technique for characterising ischaemic-penumbra (AUC=0.73 [0.64-0.81]) and infarct-core (AUC=0.70 [0.63-0.73]). The optimal MTT threshold was >165% and >180% for core and penumbra respectively. The optimal MTT threshold was >165% and >180% for core and penumbra respectively. By volume analysis; the SVDd and Maximum Slope (MS) using MTT were the best algorithms for estimation of penumbra and core respectively. Estimates of core volume were weak (all R2<0.02). Processing algorithm influenced model accuracy (AUC-range: 0.700.73 [core], 0.67-0.72 [penumbra]) and optimal tissue parameter and threshold. MTT was the most consistent optimal parameter across algorithms. The optimal MTT threshold varied from >120% to >200% for core and 155% to 195% for penumbra. CTP has diagnostic utility in POCI. There were notable differences in optimal parameter and threshold by algorithm. Clinicians should be aware of the specific algorithm used in their CTP processing software and apply caution when comparing output maps between vendors. CTP = CT Perfusion; POCI = Posterior circulation infarction, ACS = Anterior circulation stroke, ROC = Reciever operating curve, AUC = Area under the curve, SVD = Singular value deconvolution, SVDd = Singular value deconvolution with delay and dispersion correction, MTT = Mean transit Time, TTP = Time to Peak, DT = Delay time, TMax = Time to maximum of the tissue resiude curve, CBV = Cerebral blood volume, CBF = Cerebral blood flow, AIF = Arterial input function, VOF = Venous output function, EVT = endovascular thrombectomy, mRS = modified rankin score, LKW = Last known well, MVD = mean volumetric difference.

Optimized network-centric MPC using time-delay autoregressive model

In the realm of network control systems, the presence of uncertain factors, notably network delays, frequently precipitates a deterioration in control performance and system stability. To address this formidable challenge, we introduce a pioneering network control algorithm. This novel approach establishes an auto-regressive model to predict network time delays. The predictive model uses the parameter self-tuning Least Mean Square (LMS) algorithm for real-time prediction. Subsequently, we employ an enhanced generalized predictive control method rooted in the state-space model to rectify the adverse effects of time delays adeptly. Through comprehensive simulation studies, we substantiate the efficacy of our proposed method, showcasing its capacity for proficient time delay compensation and real-time performance enhancement. Its low computational requirements make it suitable for real-time applications. Furthermore, our technique showcases robustness in the face of interference and data loss, fortifying its effectiveness and applicability.

Larmor and delay times in transient quantum tunnelling

Abstract We derive a time-dependent solution for the Schrödinger-Pauli equation within a quantum shutter model to analyse cut-off plane waves scattered by a finite-range potential under a constant magnetic field. Exact analytical solutions for the time-dependent spinor components are derived for the low-energy plane-wave case, enabling the exploration of dynamical effects within the transmission region of a potential barrier. We demonstrate that the spinor probability density exhibits a diffraction in time pattern, with peaks shifted by the presence of the magnetic field relative to the field-free case. This shift introduces a delay time, which we analyse as a function of the Larmor frequency, with tunable peak positions controlled by the field intensity. We further explore the dynamical features of the spin expectation values 〈S k 〉, which exhibit unique diffraction in time behaviour and converge to stationary values in the long-time asymptotic regime. Additionally, we show that measuring the average total spin of the system offers an alternative approach for calculating the dynamical delay time. For infinitesimally small magnetic fields, we define a characteristic dynamical Larmor timescale associated with the evolution of 〈S y 〉, enabling the recovery of the Büttiker Larmor time, τ y , at low energies in the long-time limit. These findings demonstrate that magnetic fields can precisely manipulate tunnelling timescales in quantum systems, providing a means to control matter wave dynamics.

Resilient Control Strategies for Probabilistic Nonlinear Systems With Time Delays Subject to Scaling Attacks

ABSTRACTThis paper presents an observer‐based control strategy for time‐delay systems, where the time delay is considered to be variable to better reflect real‐world applications. The system is further subjected to randomly varying input nonlinearity and scaling attacks. The input nonlinearity, exhibiting stochastic behavior, is modeled using a probabilistic framework with uncertain probabilities. To effectively characterize scaling attacks, a comprehensive model is introduced. The primary objective of this study is to establish tractable stability conditions with reduced conservatism. Using the Lyapunov–Krasovskii approach, a robust observer‐based control strategy is developed, ensuring stability of the system. To further refine the stability conditions, delay fractionizing and matrix inequality techniques are employed, making the results dependent on the delay fraction size. By integrating these techniques, the proposed approach offers a systematic solution to the challenges associated with time‐delay systems featuring variable delays and random input nonlinearity. Finally, numerical examples are provided to validate the effectiveness of the proposed control strategy, demonstrating its ability to achieve the desired system performance under the given conditions.

A Chemical Kinetic Mechanism Reduction Method with Autoencoder for Hydrocarbon Fuels

ABSTRACT A chemical kinetic mechanism reduction method based on autoencoder (CRAE) is proposed to obtain the skeletal mechanism of hydrocarbon fuels. Based on the network architecture of autoencoder, a computational network structure is constructed using the species molar concentration as the input and output layers. The training datasets are generated from numerical simulations of zero-dimensional homogeneous ignition process using detailed chemical kinetic mechanisms under diverse operating conditions, and the autoencoder is optimized by using back-propagation algorithm and gradient descent algorithm. Subsequently, the weight coefficients connecting the input layer to the first hidden layer are calculated to assess the importance of chemical species, which in turn determines whether a species and its associated elementary reactions can be removed. The skeletal mechanisms for methane and n-heptane generated by using the present CRAE method are compared to those produced by the path flux analysis (PFA) method and the detailed mechanism. The comparisons of the ignition delay time, temperature profiles, and the concentration of important species show that with significantly smaller number of species, the skeletal mechanisms generated by the present CRAE method are more accurate than those of PFA in a broad range of initial pressures, temperatures and equivalence ratios. The CRAE method provides a new and effective means for reduction complex combustion kinetic mechanism of hydrocarbon fuels.

Cinematic Popcorn Park: Revolutionizing Movie Time with Integrated Ticketing and Smart Parking

Abstract - The Theater Parking concept, titled Cinematic Popcorn Park, is an innovative and integrated solution aimed at enhancing the overall experience of moviegoers through seamless ticket booking and intelligent parking systems. Recognizing the common challenges faced by cinema patrons—especially in urban areas—such as last-minute parking stress and time delays, this platform offers a user-friendly interface combining real-time parking availability, advanced booking options, and smart navigation. With features like valet service, digital signage, and electric vehicle compatibility, the system focuses on user convenience and modern accessibility. Designed using user-centered design principles and backed by scalable cloud infrastructure, the solution ensures performance, reliability, and data security. Ultimately, Cinematic Popcorn Park redefines the movie-going journey by merging entertainment with logistical ease, allowing users to focus entirely on the cinematic experience. Key Words: Theater Parking, Theatergoers, Accessible Parking, Convenience, Advanced Booking

Analysis of Hydrogen Recombination Rates of Lattice-Shaped Catalysts Under Varying Concentrations of Hydrogen

This study assesses the recombination rate of a passive autocatalytic recombiner (PAR) with lattice-shaped catalysts under severe accident conditions. In order to determine the recombination rate from the difference in the hydrogen mass flow rate at the inlet and outlet of the PAR, an equation was developed using experimentally measurable data on hydrogen concentration, flow rate, pressure, and temperature. The PAR was installed within an 80-m3 test vessel capable of replicating the atmospheric conditions of a severe accident involving the rapid generation of hydrogen due to cladding oxidation following a loss of coolant in the OPR1000. The gas mixture was drawn through 1/4-in. tubing at the PAR inlet and outlet to measure the concentration of dry hydrogen, excluding steam, using a thermal conductivity sensor positioned outside the vessel. The hydrogen concentration was adjusted to account for factors such as time delays, thermohydraulic changes, and steam levels within the test vessel during the sampling process. The average recombination rate was lower when the hydrogen concentration around the PAR was increasing than when it was decreasing. It was discovered that the calculation of the hydrogen recombination rate was largely influenced by the disparity in the dry hydrogen concentration between the PAR inlet and outlet. The continuous sampling of gas from the PAR outlet can lead to fluctuations in the calculation of the recombination rate due to condensation of high-temperature steam produced by the exothermic reaction.

A Novel Model-Free Nonsingular Fixed-Time Sliding Mode Control Method for Robotic Arm Systems

This paper introduces a novel model-free nonsingular fixed-time sliding mode control (MF-NFxTSMC) strategy for precise trajectory tracking in robot arm systems. Unlike conventional sliding mode control (SMC) approaches that require accurate dynamic models, the proposed method leverages the time delay estimation (TDE) approach to effectively estimate system dynamics and external disturbances in real-time, enabling a fully model-free control solution. This significantly enhances its practicality in real-world scenarios where obtaining precise models is challenging or infeasible. A significant innovation of this work lies in designing a novel fixed-time control framework that achieves faster convergence than traditional fixed-time methods. Building on this, a novel MF-NFxTSMC law is developed, featuring a novel singularity-free fixed-time sliding surface (SF-FxTSS) and a novel fixed-time reaching law (FxTRL). The proposed SF-FxTSS incorporates a dynamic proportional term and an adaptive exponent, ensuring rapid convergence and robust tracking. Notably, its smooth transition between nonlinear and linear dynamics eliminates the singularities often encountered in terminal and fixed-time sliding mode surfaces. Additionally, the designed FxTRL effectively suppresses chattering while guaranteeing fixed-time convergence, leading to smoother control actions and reduced mechanical stress on the robotic hardware. The fixed-time stability of the proposed method is rigorously proven using the Lyapunov theory. Numerical simulations on the SAMSUNG FARA AT2 robotic platform demonstrate the superior performance of the proposed method in terms of tracking accuracy, convergence speed, and control smoothness compared to existing strategies, including conventional SMC, finite-time SMC, approximate fixed-time SMC, and global fixed-time nonsingular terminal SMC (NTSMC). Overall, this approach offers compelling advantages, i.e., model-free implementation, fixed-time convergence, singularity avoidance, and reduced chattering, making it a practical and scalable solution for high-performance control in uncertain robotic systems.

Beyond the linear model in concentration-QT analysis

The white-paper regression model is the standard method for assessing QT liability of drugs. The quantity of interest, placebo-corrected QTc change from baseline (ΔΔQTc) with corresponding confidence interval (CI), is derived from the difference in model-estimated ΔQTc for active compound and placebo in a linear model. Model assumptions include linearity and no time delay between change in concentration and change in ΔQTc. Alternative models are commonly not considered unless there is a clear indication of inappropriateness of the assumptions. This work introduces several extensions for concentration-QT modeling in a pharmacometric context. The model is formulated as linear drug-effect model with treatment, nominal time, and centered baseline as covariates on the intercept. This approach enables straightforward use of other concentration-ΔQTc relationships, including loglinear, Emax, and indirect-effects models. In addition, the setup allows for the use of pharmacometric model assessments for ΔQTc and ΔΔQTc, including visual predictive checks and quantitative model comparison based on the Bayesian information criterion. The proposed approach is applied to several compounds from a previously published QTc study. The results suggest that a nonlinear mixed-effects model for ΔΔQTc and comparing a set of candidate models quantitatively can be a more powerful approach than fitting only the white-paper regression model. A semi-automated approach that compares nonlinear and hysteresis models to the linear model enables a reliable choice of the best model and determination of the degree of prolongation at the concentration of interest. Standard pharmacometric tools can assess the appropriateness of the models and the potential extent of hysteresis.

Global dynamics for a class of nonautonomous mosquito models with time delay and switching control strategy

Global dynamics for a class of nonautonomous mosquito models with time delay and switching control strategy

Evaluation of visual function and morphological changes in patients with adrenoleukodystrophy using SS-OCT and PVEP.

This study aims to evaluate visual function and morphological changes in patients with adrenoleukodystrophy (ALD) through sweep-source optical coherence tomography (SS-OCT) and patterned visual evoked potentials (PVEP), with the goal of providing more accurate and comprehensive data for the diagnosis, monitoring, and assessment of treatment efficacy in patients with ALD. This study included 46 ALD patients and 44 healthy controls. The thickness of the retinal nerve fiber layer (RNFL) around the optic disc, as well as the macular RNFL and ganglion cell-inner plexiform layer (GCIPL) thickness, was assessed using SS-OCT. The peak time and amplitude of the P100 wave were also measured using PVEP. Factors that were statistically significant in the univariate analysis were subjected to stepwise binary logistic regression analysis for further investigation. Predictive performance was evaluated by constructing receiver operating characteristic (ROC) curves and compared using DeLong's test. Compared with the control patients, ALD patients presented a significant increase in the peak time of the P100 wave (P < 0.05); however, no notable difference in amplitude was observed (P > 0.05). Additionally, substantial decreases in the RNFL and GCIPL thicknesses were observed within the parafoveal ring, especially in the superior and nasal quadrants (P < 0.05). The area under the curve for the binary logistic stepwise regression model was 0.883, with a sensitivity of 0.95, which surpassed the performance of the individual parameters. ALD patients present with abnormal retinal structures and a PVEP peak time delay. Combining these two parameters could increase the accuracy of an early ALD diagnosis.

One-Step Synthesis AlCo2O4 and Derived “Al” to Double Optimise the Thermal Decomposition Kinetics and Enthalpy of Ammonium Perchlorate

The solution combustion method is widely used because of its simple operation and ability to produce porous structures. The chemical composition and morphological structure of the material can be regulated by different oxidiser-to-fuel ratios (φ). In this work, AlCo2O4 derived “Al” catalytic materials were successfully synthesised by adjusting the fuel-to-oxidiser ratio using a one-step solution combustion method. On the one hand, the aluminium nanoparticles act as a part of the metal fuel in the composite solid propellant and, at the same time, serve as a catalytic material. In contrast, the thermal decomposition performance of AP was significantly improved by the synergistic catalysis of AlCo2O4. Among the samples prepared under different fuel ratios, considering all aspects (high-temperature decomposition temperature, activation energy, and decomposition heat) comprehensively, the AlCo2O4 prepared with φ = 0.5 had a more excellent catalytic effect on AP thermal decomposition, and the THTD of AP was reduced to 285.4 °C, which is 188.08 °C lower. The activation energy of the thermal decomposition of AP was also significantly reduced (from 296.14 kJ/mol to 211.67 kJ/mol). In addition, the ignition delay time of AlCo2O4-AP/HTPB was drastically shortened to 9 ms from 28 ms after the addition of 7% AlCo2O4 derived “Al” catalytic materials. Composite solid propellants have shown great potential for application.

Observer‐based finite‐time control of conformable Takagi–Sugeno fuzzy systems with time delay

ABSTRACTThis paper examines finite‐time (F‐T) observer‐based control of fractional‐order nonlinear systems with time delay, employing the Takagi–Sugeno fuzzy (T‐SF) approach. This study utilizes the conformable fractional derivative (CFD) as its foundational framework. Sufficient conditions are formulated to guarantee that the augmented vector, consisting of the state estimates and the state estimation errors, stays within a ball centered at the origin. This applies not only to specified initial conditions but also to predefined disturbances. These conditions are then reformulated as linear matrix inequalities (LMIs) conditions, which can be efficiently solved using the LMI toolbox. An illustrative example is given to illustrate the proposed result.

Computational modeling and dynamical analysis for B. subtilis competence genic regulation circuit with multiple time delays and external noisy regulation

Computational modeling and dynamical analysis for B. subtilis competence genic regulation circuit with multiple time delays and external noisy regulation

VALIDITY AND RELIABILITY OF THE TURKISH VERSION OF THE PREMATURE EJACULATION TREATMENT EVALUATION (PETO) SCORING SYSTEM

VALIDITY AND RELIABILITY OF THE TURKISH VERSION OF THE PREMATURE EJACULATION TREATMENT EVALUATION (PETO) SCORING SYSTEM

Thin-film transistor-based micro light-emitting diode circuits for achieving short delay time by controlling operation sequence in mobile displays

This study proposed a micro light-emitting diode (µLED) pixel circuit with a short µLED current (I µLED) delay time for mobile displays. A pixel circuit using complementary metal-oxide-semiconductor-type low-temperature polycrystalline silicon (LTPS) thin-film transistors (TFTs) was designed. The proposed pixel circuit used n-type LTPS TFTs as driving and emission TFTs for pulse width modulation and controlled the µLED operation sequence from the off- to the on-state. Because the pixel circuit’s input signal characteristics could affect the I µLED delay time, the researchers also developed an integrated driver circuit with multiple output signals to operate the proposed pixel circuit. The pixel circuit operations were simulated by connecting the proposed pixel and integrated driver circuits. Consequently, the proposed pixel circuit exhibited a short I µLED delay time of 2.8 µs by enhancing the controllability over the driving TFTs for pulse amplitude modulation during µLED transition. The featured circuits can operate in normal and always-on display modes. The proposed circuits could be integrated into a 320 pixels per inch display based on the layout design. Therefore, the proposed pixel circuit can help improve low gray level expression capability because of the short I µLED delay time and can be used for high-resolution mobile µLED displays.

Testing Cumulative Lexicalized Effects in Study Abroad: Variable Subject Pronoun Expression in Spanish as an Additional Language

We examine variable first-person singular subject pronoun expression in Spanish learner data to investigate the effects of study abroad in Mexico and Spain on the acquisition of sociolinguistic variation. In addition to exploring pre- and post-study abroad effects, this work considers whether such impacts wane over time after the study abroad experience. We include in the analyses novel usage-based factors estimating lexically specific usage patterns. We conduct a mixed-effects linear regression model predicting overt yo (‘I’) expression. Results indicate that overt yo expression is more likely after studying abroad (compared to pre-study abroad). Additionally, learners acquire a usage-based pattern of variation evident after the study abroad experience. This effect is not just apparent immediately after studying abroad, but it persists in data collected after a time delay.

State feedback H ∞ control design using asymmetric Lyapunov–Krasovskii functional for vehicle active suspension system

This paper presents a state feedback H ∞ control design for active suspension systems with time-delays using an asymmetric Lyapunov–Krasovskii functional (LKF). Less conservative stabilization conditions are derived in this paper for the design of a state feedback control synthesis through asymmetric LKF in the linear matrix inequalities (LMIs). This investigation aims to exploit the capability of asymmetric LKF to minimize conservativeness and utilizes Jensen’s and Wirtinger’s bounded integral inequalities to handle cross-terms in the asymmetric LKF derivative. One of the key benefits of the asymmetric LKF, compared to symmetric LKF, is its capability to provide less conservative stability conditions by relaxing the condition that all the matrix variables should be symmetric or positive definite. Capitalizing on the potential of asymmetric LKF to realize a less conservative state feedback H ∞ control design, this study evaluates the performance on a multi-objective quarter-vehicle active suspension system (ASS) for various realistic road profiles. Simulation results of bump road surface and random road profiles along with the frequency responses indicate that despite the time delays in the feedback loop the proposed H ∞ controller improves the closed-loop suspension system performance significantly. Quantitative analysis of the chassis acceleration and suspension travel corroborates that compared to the performance of H ∞ controller and predictor-based feedback controller designed using symmetrical LKF, the proposed control scheme reduces the body acceleration and tyre deflection RMS values by 16.5% and 8% when compared to H ∞ control and by 21.5% and 13.5% when compared to predictor-based state feedback control, respectively.