Transit Time Research Articles

Sleep apnea patients with epiglottic collapse elevate their larynx more with swallowing; videofluoroscopic swallowing study of 80 patients.

The epiglottis plays an integral role in the swallowing mechanism and is also implicated as an obstruction site in obstructive sleep apnea (OSA). The underlying causes of epiglottic collapse during sleep remain unclear. This study aimed to investigate the cognitive functions using the Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) and the neurophysiological and anatomical factors using videofluoroscopic swallowing studies (VFSS). We compared patients with OSA exhibiting epiglottic collapse to those without, assessing differences in anatomical or neurophysiological characteristics. The study included 12 patients with epiglottic collapse (Epi-group) and 68 without (non-Epi group), all undergoing overnight polysomnography (PSG), drug-induced sleep endoscopy (DISE), LOTCA, and VFSS. Oral transit time (OTT), pharyngeal delay time (PDT), and pharyngeal transit time (PTT) were considered as neurophysiological traits, and laryngeal elevation length (LE) as anatomical trait, and were measured across various test diets (10ml of liquid, soft, or solid). The study comprised 80 individuals, 57 men and 23 women, with no significant age, sex, body mass index or PSG parameters between groups, or DISE findings, with the exception of epiglottic collapse. Swallowing metrics from VFSS were normal, with no differences in OTT, PDT, PTT, or LOTCA scores. Notably, patients with epiglottic collapse showed a greater laryngeal elevation when swallowing soft and solid foods (p = 0.025 and p = 0.048, respectively). Patients with epiglottic collapse do not exhibit neurophysiological or cognitive impairments when compared to non-Epi group. However, the Epi-group displayed a significantly increased laryngeal elevation length. This suggests that anatomical factors may have a more substantial role in the development of epiglottic collapse than neurophysiological factors.

Frequency-Dependent Variability of Pulse Wave Transit Time: Pilot Study.

The dynamics of the pulse wave (PW) associated with the PW transit time variability (PWTTV) determines the peripheral pulse rate variability, which is used as a surrogate for heart rate variability (HRV). The aim of the work is to analyze the frequency-dependent dynamics of PWTTV and to identify the possible frequency-phase modulation of PW velocity oscillations on the transit from the heart to the soft tissues of the distal parts of the upper extremities. RR-interval recordings and synchronous records of photoplethysmograms of 12 conditionally healthy subjects from the PhysioNet open database were used in this work. Using the Hilbert-Huang transform 3 spectral components of PWTTV and HRV were identified. It was shown that the amplitudes of PWTTV oscillations were many times (up to 8.4 times) smaller than the amplitudes of HRV, and the peaks of PWTTV spectral components were shifted towards higher frequencies than those of HRV. Functional relations between PWTTV and HRV, which can determine the phase modulation of periodic changes in the PW propagation velocity, were revealed.

Diagnosis of Chronic Constipation.

Patients with chronic constipation (CC) usually complain of mild to severe symptoms, including hard or lumpy stools, straining, a sense of incomplete evacuation after a bowel movement, a feeling of anorectal blockage, the need for digital maneuver to assist defecation, or reduced stool frequency. In clinical practice, healthcare providers need to check for 'alarm features' indicative of a colonic malignancy, such as bloody stools, anemia, unexplained weight loss, or new-onset symptoms after 50 years of age. In the Seoul Consensus on the diagnosis and treatment of chronic constipation, the Bristol stool form scale, colonoscopy, and digital rectal examination are useful for objectively evaluating the symptoms and making a differential diagnosis of the secondary cause of constipation. If patients with CC improve to lifestyle modification or first-line therapies, the effort to determine the subtypes of CC is usually not considered. On the other hand, if conventional therapeutic strategies fail, diagnostic testing needs to be considered to distinguish between the different subtypes of functional constipation (normal-transit constipation, slow transit constipation, or defecatory disorder) because these subtypes of constipation have different therapeutic implications and a correct diagnosis is critical. In the Seoul consensus, physiological testing is recommended for patients with functional constipation who have failed to respond to treatment with available laxatives (for a minimum of 12 weeks and recommended a therapeutic regimen) or who are strongly suspected of having a defecatory disorder. The Seoul consensus contains statements of physiological testing, including balloon expulsion test, anorectal manometry, defecography, and colon transit time.

A deflected ray model of the transit time difference in ultrasonic flow meters applied to non-ideal flow profiles

Transit time difference (TTD) ultrasonic meters have widespread applications due to their high dynamic range, lack of moving parts and low maintenance requirements. In earlier work, the TTD is considered to arise due to the fluid flow changing the effective speed of sound along a fixed ray path, but recent publications have introduced a new way of viewing how the TTD arises. The flow velocity in the axial direction does not affect the speed of sound in the direction normal to the pipe wall. Therefore, in a clamp-on meter with the fluid at constant temperature and pressure, the transit time in the liquid must be constant with changing flow rate. The TTD then arises due to the ray path in the water being deflected, and the received wavefront travelling some extra distance along the pipe axis, which results in a different transit through the transducer wedge than for zero flow conditions. In a meter with wetted transducers, the mechanism causing the TTD is slightly different. The deflected ray travels a different distance in the fluid along the direction normal to the pipe walls due to the transducer surface being at an angle to the flow direction, and this is responsible for the TTD that is measured.Previous work has focused on calculating the magnitude of the ray deflection effect in clamp-on meters for ideal flow conditions, where the flow velocity does not depend on the position in the pipe. In this article, the ray deflection is calculated for a series of analytic profiles, and it is shown that the two models result in the same calculated TTD for both clamp-on meters and meters with wetted transducers at low flow speeds. The hydraulic correction factors calculated using the model which considers a change in the effective speed of sound are recovered using the ray deflection models. The resulting equations for beam deflection are the same as those for the conventional fixed ray path model, but the beam deflection model is more physically realistic and presents new opportunities for calibration methods utilising carefully controlled movement of the transducers. The conventional model typically has a correction factor which is allowed to vary in cases where the flows are expected to approach the speed of sound to account for the effect of ray deflection. However, the ray deflection model automatically takes this into account, so is expected to be useful in these circumstances.

#279 The impact of synbiotics on the uremic toxins, inflammation, and gut microbiome of CKD patients—randomized, double-blind, placebo-controlled trial

Abstract Background and Aims The microbiome represents a complex system of microorganisms coexisting within the human body. The intestinal tract is the most densely populated region and is essential in preserving health and developing diseases such as chronic kidney disease (CKD). The relationship between the gut microbiome and the kidney is complex. CKD can significantly affect the composition of the gut microbiome, which, through the fermentation process, participates in the production of over 90 different uremic toxins with the potential to aggravate systemic inflammation, oxidative stress, and decrease renal function. Indoxyl-sulfate (IS), p-cresyl-sulfate (PCS), and trimethylamine-N-oxide (TMAO) are the most closely studied. Supplementation with pre-, pro-, or synbiotics could reduce the production and improve the intestinal clearance of uremic toxins. Assessing the efficacy and safety of this potential strategy has been the aim of our randomized, double-blind, placebo-controlled study. Method A total of 84 patients, aged over 18 years, with an estimated glomerular filtration rate (eGFR) between 15 and 45 ml/min, were randomized into two groups, the one treated with synbiotic—64 billion colonies of Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium lactis with 6.4 g of inulin in the form of capsules, and a control group treated with an identical number and appearance of capsules but with a total of 6.8 g of bioinert maltodextrin, over a period of 12 weeks. Strict control of the diet and the use of antibiotics and other probiotics was carried out. The study examined the effect of therapy on the serum level of the uremic toxins IS, PCS, and TMAO, the composition of the stool microbiome, the serum level of interleukin 6 (IL6), high-sensitivity C-reactive protein (hs-CRP), eGFR, albuminuria, degree of liver steatosis according to ultrasound elastomeric measurement, occurrence of gastrointestinal symptoms and gut transition time. The level of uremic toxins was determined using ultra-performance liquid chromatography. To determine the composition of the intestinal microbiome, we used 16s rRNA amplicon sequencing targeting the V3-V4 hypervariable region. Results The synbiotic treatment significantly reduced the levels of IS (−11% vs. 1%, p = 0.033) and PCS (−6% vs. 0%, p = 0.011) in the intervention arm. We also observed that treatment with the synbiotic significantly reduced hsCRP levels (ΔhsCRP 0 vs −29%, p = 0.03). Synbiotic treatment greatly enriched the intestinal microbiome with the genera Lactobacillus, Bifidobacterium, and Faecalibacterium by 81%, 55%, and 40%, respectively, with a reduction in the genera Ruminococcus and Enterobacterium by 35% and 40%. The use of synbiotics led to a significant reduction of liver steatosis according to the dynamics of the attenuation coefficient—ATT (ΔATT% −0.6 vs −2.3%, p = 0.33), with a decrease in the serum alanine aminotransferase—ALT (ΔALT −19% vs −28%, p = 0.035). A statistically significant shortening of the gut transition time—GTT was observed in the intervention arm (ΔGTT −5 h vs −10 h, p = 0.031), paralleled by a reduction in the intensity and prevalence of constipation symptoms. No side effects were observed. Conclusion Synbiotics could be an effective, safe, and affordable therapy that could be used to modify the intestinal microbiome of CKD patients and contribute to the reduction of the level of uremic toxins, inflammation, degree of fatty liver, shorten gut transit time and reduce the symptoms of constipation.

#751 Noninvasive evaluation of histopathology in immunoglobulin A nephropathy by contrast-enhanced ultrasonography

Abstract Background and Aims IgA nephropathy is a common primary glomerulonephritis. Renal pathology provides a visual reflection of renal lesions, but percutaneous renal biopsy carries risks This study explores a non-invasive method for evaluating the renal pathological changes in IgA nephropathy patients. We attempt to correlate contrast-enhanced ultrasonography parameters with IgA nephropathy pathological changes, discussing the potential value of this approach in assisting the assessment of IgA nephropathy renal pathology. Method This prospective study included 26 IgAN cases eventually confirmed through renal pathology. Prior to renal biopsy, patients underwent contrast-enhanced ultrasound examination and conventional renal ultrasound. Ultrasound contrast parameters, including time-intensity curve (TIC) peak intensity, time to peak, rise time, and mean transit time, were recorded. Correlation analyses were conducted between conventional ultrasound, contrast-enhanced ultrasound parameters, clinical data, and pathology scores. Results Significant differences in peak intensity were observed between different Oxford C scores, with significant statistical differences between C0 and C1, as well as C0 and C2 (P < 0.05). Quantitative analysis revealed correlations between peak intensity, time to peak, and C scores (r = −0.571, P < 0.05; r = 0.498, P < 0.05). Time to peak correlated with T scores (r = −0.445, P < 0.05). No correlations were found between other contrast-enhanced ultrasound parameters and Lee's grading, Oxford MEST-C M, E, or S scores. Conclusion Contrast-enhanced ultrasonography parameters, specifically time-intensity curve peak intensity and time to peak, correlate with renal pathology C scores. Contrast-enhanced ultrasound holds clinical significance in the non-invasive assessment of renal pathological changes in IgA nephropathy patients.

Effects of Thickening Agents on the Mucociliary Transport Function: Comparison by the Type of Thickening Agents and the Viscosity of Thickened Water.

Thickening agents effectively prevent liquid aspiration, but their impact on the ease of discharging aspirated liquids from the trachea remains unclear due to alterations in the physical properties of liquids. This study clarifies the effects of thickening agents, comprising various raw materials, on mucociliary transport function, focusing on the viscosities of thickened waters. The subjects were 23 healthy adults. Five types of saccharin solution were prepared: a solution without a thickening agent, a starch-based nectar-like solution, a starch-based honey-like solution, a xanthan-gum-based nectar-like solution, and a xanthan-gum-based honey-like solution. Using these five types of saccharin solutions randomly, each subject underwent five trials of the saccharine dye test to evaluate the mucociliary transport function of the respiratory tract. The saccharin time was defined as the time from the placement of the saccharin solution on the nasal vestibule of the subject to when the subject reported that they became aware of the sweetness. The saccharin transit times for all samples of thickened water were longer compared to those of water without a thickening agent (p < 0.01). A comparison between thickened water samples with different viscosities showed that the saccharin transit time was longer when thickened water samples with high viscosity were prepared using the same thickening agent (p < 0.01). This suggests that while thickening reduces aspiration, the use of thickening agents may increase the difficulty in discharging aspirated fluids from the trachea.

Imaginary past of a quantum particle moving on imaginary time

The analytical continuation of classical equations of motion to complex times suggests that a tunneling particle spends in the barrier an imaginary duration i|T|. Does this mean that it takes a finite time to tunnel, or should tunneling be seen as an instantaneous process? It is well known that examination of the adiabatic limit in a small additional AC field points towards |T| being the time it takes to traverse the barrier. However, this is only half the story. We probe the transmitted particle's history, and find that it very little of the field's past behavior, as if the transit time were close to zero. The ensuing contradiction suggests that the question is ill posed, and we explain why. Published by the American Physical Society 2024

Integrating Clopidogrel's First-Pass Effect in a Joint Semi-Physiological Population Pharmacokinetic Model of the Drug and Its Inactive Carboxylic Acid Metabolite.

Clopidogrel (CLO), a pro-drug for preventing thrombotic events, undergoes rapid absorption and extensive metabolism, with approximately 85-90% converted to an inactive carboxylic acid metabolite (CLO-CA) and the remaining to an active thiol (CLO-TH). Few pharmacokinetic models for the drug and its metabolites exist, with most focusing on CLO-TH. Although CLO-CA is inactive, its predominant (compared to its parent drug and metabolites) presence in plasma underscores the importance of characterizing its formation and pharmacokinetic profile. This study aimed to characterize the process of the absorption of CLO and its conversion to CLO-CA via developing a population pharmacokinetic model. Individual participants' data from two bioequivalence studies were utilized. Extensive blood samples were collected at predetermined intervals, including 841 concentrations of CLO and 1149 of CLO-CA. A nonlinear, mixed-effects modelling approach using NONMEM® software (v 7.5) was applied. A one-compartment model was chosen for CLO, while a two-compartment proved optimal for CLO-CA. Absorption from the depot compartment was modeled via two transit compartments, incorporating transit rate constants (Ktr). A semi-physiological model explained the first-pass effect of CLO, integrating a liver compartment. The estimated mean transit times (MTTs) for the studies were 0.470 and 0.410 h, respectively. The relative bioavailability for each study's generic medicine compared to the reference were 1.08 and 0.960, respectively. Based on the estimated parameters, the fractions metabolized to inactive metabolites (FiaM_st1 and FiaM_st2) were determined to be 87.27% and 86.87% for the two studies, respectively. The appropriateness of the final model was confirmed. Our model offers a robust framework for elucidating the pharmacokinetic profiles of CLO and CLO-CA.

Foraging Attributes of Insect Pollinators on Tulsi (Ocimum basilicum)

Pollination is an intricate relationship between plants and pollinators; this interaction is the best example of mutualism where pollinators utilize floral rewards while pollination accomplished on plants. Pollination ecology of tulsi (Ocimum basilicum) is poorly understood. Foraging attributes: foraging rate, foraging speed and transit time of pollinators are key performance indicator to determine their pollination efficiency. Foraging speed and foraging rate were recorded during blooming period with the help of stopwatch and transit time was calculated from foraging rate and foraging speed. The performance of seven pollinators; Apis florea, Amegilla cingulata, Megachile femoratella, Megachile sp., Apis cerana, Apis dorsata and Apis mellifera were evaluated on the basis of foraging attributes. Foraging rate, foraging speed and transit time varied during the blooming period week to week and pollinator species to species. The maximum foraging rate was observed with A. mellifera, maximum foraging speed was observed with A. florea and minimum transit time as well as wasted minimum time was calculated with A. mellifera. The maximum foraging rate, foraging speed and minimum transit time were observed with all the pollinators at the peak of blooming period. Based on foraging attributes A. mellifera performance was better than other pollinators on Tulsi.

Noninvasive assessment of Ki-67 labeling index in glioma patients based on multi-parameters derived from advanced MR imaging.

To investigate the predictive value of multi-parameters derived from advanced MR imaging for Ki-67 labeling index (LI) in glioma patients. One hundred and nine patients with histologically confirmed gliomas were evaluated retrospectively. These patients underwent advanced MR imaging, including dynamic susceptibility-weighted contrast enhanced MR imaging (DSC), MR spectroscopy imaging (MRS), diffusion-weighted imaging (DWI) and diffusion-tensor imaging (DTI), before treatment. Twenty-one parameters were extracted, including the maximum, minimum and mean values of relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), relative mean transit time (rMTT), relative apparent diffusion coefficient (rADC), relative fractional anisotropy (rFA) and relative mean diffusivity (rMD) respectively, and ration of choline (Cho)/creatine (Cr), Cho/N-acetylaspartate (NAA) and NAA/Cr. Stepwise multivariate regression was performed to build multivariate models to predict Ki-67 LI. Pearson correlation analysis was used to investigate the correlation between imaging parameters and the grade of glioma. One-way analysis of variance (ANOVA) was used to explore the differences of the imaging parameters among the gliomas of grade II, III, and IV. The multivariate regression showed that the model of five parameters, including rCBVmax (RC=0.282), rCBFmax (RC=0.151), rADCmin (RC= -0.14), rFAmax (RC=0.325) and Cho/Cr ratio (RC=0.157) predicted the Ki-67 LI with a root mean square (RMS) error of 0. 0679 (R2 = 0.8025).The regression check of this model showed that there were no multicollinearity problem (variance inflation factor: rCBVmax, 3.22; rCBFmax, 3.14; rADCmin, 1.96; rFAmax, 2.51; Cho/Cr ratio, 1.64), and the functional form of this model was appropriate (F test: p=0.682). The results of Pearson correlation analysis showed that the rCBVmax, rCBFmax, rFAmax, the ratio of Cho/Cr and Cho/NAA were positively correlated with Ki-67 LI and the grade of glioma, while the rADCmin and rMDmin were negatively correlated with Ki-67 LI and the grade of glioma. Combining multiple parameters derived from DSC, DTI, DWI and MRS can precisely predict the Ki-67 LI in glioma patients.

Edge-Terminated AlGaN/GaN/AlGaN Multi-Quantum Well Impact Avalanche Transit Time Sources for Terahertz Wave Generation

Edge-Terminated AlGaN/GaN/AlGaN Multi-Quantum Well Impact Avalanche Transit Time Sources for Terahertz Wave Generation

Improving Short-Haul Intermodal Transit Times on Low-Density Rail Corridors with Platoons of Self-Propelled Autonomous Railcars

U.S. freight railroads consume in excess of 13 billion liters of diesel fuel yearly. Although efforts to improve energy efficiency and reduce emissions have made substantial progress in the last decades, the benefits are relatively incremental and will not be sufficient to realize full decarbonization. Several independent efforts are underway to develop alternative locomotive fuels and propulsion technologies designed to fit within the typical locomotive envelope. In addition to these more conventional efforts, multiple startup companies are working to develop self-propelled autonomous railcars (SPARCs) that can achieve targeted decarbonization levels while also disrupting the traditional railroad operating paradigm. SPARC operations with multiple platoon lengths, as well as a control scenario with a conventional train length of 110 railcars, were simulated on an example corridor linking a port with an inland intermodal terminal. This line was single track with short sidings on inconsistent intervals, which is typical of U.S. branch lines serving few local customers without heavy through traffic. For all traffic levels simulated, SPARCs had a much lower transit time than the conventional trains. Optimal platoon length varied between 15- and 38-vehicles per platoon depending on the traffic demand, well under North American standards of over 100 railcars per train.

EARLY RESULTS OF MINIMALLY INVASIVE CORONARY ARTERY BYPASS GRAFTING

Abstract Coronary artery bypass grafting (CABG) is the benchmark in elective revascularization for Coronary Artery Disease (CAD), particularly for complex or multivessel CAD, left main coronary involvement, diabetes, or impaired heart function. Traditional CABG, via median sternotomy using cardiopulmonary bypass (CPB), has limitations like CPB–related morbidity and sternal complications. Alternatives like Minimally Invasive Cardiac Surgery (MICS CABG) and Hybrid Revascularization (HR) aim to address these drawbacks. We present a series of 215 consecutive patients (mean age 67±9 years, 27.9% females, EuroSCORE II 1.5±1.3%) between 2017–2023 who underwent elective minimally invasive surgical revascularization. Among the cohort, 164 (76.3%) had Minimally Invasive Direct Coronary Artery Bypass (MIDCAB) via anterolateral left mini–thoracotomy (ALMT) at the fifth intercostal space (IS), with 140 (85.4%) receiving a single left internal thoracic artery (LITA) graft to the left anterior descending (LAD) artery and 24 (14.6%) an additional distal anastomosis. Thirty–four (20.7%) had HR via percutaneous coronary intervention (PCI) on the right coronary artery (RCA). Of the total cohort, 35/215 patients (16.3%) underwent multivessel MICS CABG via ALMT, with mean 2.3±0.5 distal anastomoses using LITA, right ITA, radial artery, or saphenous vein. Heart manipulation was via a subxiphoid device. Four MICS CABG patients (11.4%) had HR. More than half of MICS CABG cases were performed with planned peripheral CPB, without cross–clamping the Aorta. Of the total cohort, 16/215 patients (7.4%) received MICS CABG in an endoscopic fashion, using 3D thoracoscopy for LITA and RITA harvesting via bilateral ports in the 2nd, 3rd, and 4th IS, employing peripheral CPB and aortic clamping by Chitwood clamp at the second IS, with cardioplegia delivery via a 4 cm right anterior MT. Distal anastomoses were performed via left anterior MT, with easy subxiphoid manipulation of the emptied heart. Transit time flowmetry was used in all cases. Conversion to sternotomy was needed in 3 cases, all were MIDCAB. Thirty–day mortality was 1.4%, median ventilation was 4 [2–5] hours, and Intensive Care Unit–stay was 1 [1–2] days. All patients received graft evaluation via computerized tomography before hospital discharge. Mean follow–up was 2.9±1.9 years (max 5 years), with no deaths and 4 (1.9%) requiring follow–up PCI. MICS CABG is a promising future technique for heart revascularization by dedicated teams.

Subtype prediction of intrahepatic cholangiocarcinoma using dynamic contrast-enhanced ultrasound

ObjectiveThe study aimed to investigate the predictive value of dynamic contrast-enhanced ultrasound (DCE-US) in differentiating small-duct (SD) and large-duct (LD) types of intrahepatic cholangiocarcinoma (ICC).MethodsThis study retrospectively enrolled 110 patients with pathologically confirmed ICC lesions who were subject to preoperative contrast-enhanced ultrasound (CEUS) examinations between January 2022 and February 2023. Patients were further classified according to the subtype: SD-type and LD-type, and an optimal predictive model was established and validated using the above pilot cohort. The test cohort, consisting of 48 patients prospectively enrolled from March 2023 to September 2023, was evaluated.ResultsIn the pilot cohort, compared with SD-type ICCs, more LD-type ICCs showed elevated carcinoembryonic antigen (p < 0.001), carbohydrate antigen 19-9 (p = 0.004), ill-defined margin (p = 0.018), intrahepatic bile duct dilation (p < 0.001). Among DCE-US quantitative parameters, the wash-out area under the curve (WoAUC), wash-in and wash-out area under the curve (WiWoAUC), and fall time (FT) at the margin of lesions were higher in the SD-type group (all p < 0.05). Meanwhile, the mean transit time (mTT) and wash-out rate (WoR) at the margin of the lesion were higher in the LD-type group (p = 0.041 and 0.007, respectively). Logistic regression analysis showed that intrahepatic bile duct dilation, mTT, and WoR were significant predictive factors for predicting ICC subtypes, and the AUC of the predictive model achieved 0.833 in the test cohort.ConclusionsPreoperative DCE-US has the potential to become a novel complementary method for predicting the pathological subtype of ICC.Critical relevance statementDCE-US has the potential to assess the subtypes of ICC lesions quantitatively and preoperatively, which allows for more accurate and objective differential diagnoses, and more appropriate treatments and follow-up or additional examination strategies for the two subtypes.Key PointsPreoperative determination of intrahepatic cholangiocarcinoma (ICC) subtype aids in surgical decision-making.Quantitative parameters from dynamic contrast-enhanced US (DCE-US) allow for the prediction of the ICC subtype.DCE-US-based imaging has the potential to become a novel complementary method for predicting ICC subtypes.Graphical

An exploratory study of the relationship between pulse transit time and blood pressure based on causal inference

Aim: We propose to examine the causal relationship between the noninvasive features represented by pulse transit time (PTT) and blood pressure (BP), with the aim of mitigating the impact of confounding factor(s) and thus improving the performance of BP estimation. Methods: We identified the causal graph of BP and the important noninvasive features extracted from electrocardiogram (ECG) and photoplethysmogram (PPG) via fast causal inference (FCI) algorithm, with the orientations of the edges in the causal graph being determined by the causal generative neural networks (CGNN) algorithm. With the knowledge obtained from the causal graph, we further used hierarchical regression model to estimate BP, and validated the proposed method on 17 subjects. Results: We found that the obtained causal graph was almost consistent with the prior knowledge, and heart rate (HR) was one of the main confounding factors of PTT and BP. Incorporating HR into the hierarchical regression model to eliminate its confounding effect on the PTT-based BP estimation, the mean value of SBP and DBP estimation was improved by 1.27 and 1.89 mmHg, respectively, and the mean absolute difference (MAD) was improved by 2.28 and 3.60 mmHg, respectively. Conclusion: Causal inference-based method has the potential to clarify the causal relationship between BP and related wearable noninvasive features, which can further shed light on developing new methods for cuffless BP with acceptable accuracy.

Comparison between supervised and physics-informed unsupervised deep neural networks for estimating cerebral perfusion using multi-delay arterial spin labeling MRI.

This study aimed to implement a physics-informed unsupervised deep neural network (DNN) to estimate cerebral blood flow (CBF) and arterial transit time (ATT) from multi-delay arterial spin labeling (ASL), and compare its performance with that of a supervised DNN and the conventional method. Supervised and unsupervised DNNs were trained using simulation data. The accuracy and noise immunity of the three methods were compared using simulations and in vivo data. The simulation study investigated the differences between the predicted and ground-truth values and their variations with the noise level. The in vivo study evaluated the predicted values from the original images and noise-induced variations in the predicted values from the synthesized noisy images by adding Rician noise to the original images. The simulation study showed that CBF estimated using the supervised DNN was not biased by noise, whereas that estimated using other methods had a positive bias. Although the ATT with all methods exhibited a similar behavior with noise increase, the ATT with the supervised DNN was less biased. The in vivo study showed that CBF and ATT with the supervised DNN were the most accurate and that the supervised and unsupervised DNNs had the highest noise immunity in CBF and ATT estimations, respectively. Physics-informed unsupervised learning can estimate CBF and ATT from multi-delay ASL signals, and its performance is superior to that of the conventional method. Although noise immunity in ATT estimation was superior with unsupervised learning, other performances were superior with supervised learning.

Digital Twin and Simulation Analyses for Process Optimization of an Automated Guided Vehicle System

Development in industrial companies aims to digitize processes, ensure traceability and advance automation. Systems with automated guided vehicles (AGVs) can help meet these objectives. A core element of these systems is the higher-level system controller. When an AGV system is operated, some dynamic aspects appear. It is then to identify, that the previous specified rules for scheduling and routing of vehicles are not always proper and practical, which may result in waiting time of AGVs. That means the static performance requirements and the specifications based on them often lead to suboptimal results. A methodical problem-solving approach is to develop a digital twin as a reflection of reality and to carry out strategy analyses using simulation. For this purpose, a digital twin of the concerned AGV system with five vehicles and its technological environment is created using software of plant simulation. Various simulation scenarios are developed to simulate material flows by using different routing and scheduling rules and strategies. Drawing from the insights gained through the digital twin and simulation analyses, this study identifies novel scheduling and routing rules for the AGV system. These rules improve the overall efficiency and effectiveness of the system operations by easing traffic congestion, reducing transit time, and minimizing production downtime.

Improving traffic light systems using Deep Q-networks

As our cities become more complex and traffic demand grows, managing such traffic efficiently becomes challenging. Hence, solutions that allow building upon the current traffic light systems and that can be readily deployed are of global interest. In this work, we address the challenge of improving traffic light management at intersections. We propose an agent-based traffic light control system where an agent, one per intersection, dynamically regulates the light’s phase cycle depending on the current traffic conditions. To this end, we will rely on Deep Networks to adequately train agents to make good decisions. Simulation results in a realistic scenario using SUMO show that our proposed approach can significantly reduce waiting times, improving transit times by 44% compared to the standard fixed-timing method. Additionally, to assess the effectiveness and reliability of our control algorithm, we introduce new performance metrics.

The correlation between time-intensity curve parameters of transrectal contrast-enhanced ultrasound and pathological prognostic factors in rectal adenocarcinoma.

To investigate the correlation between time-intensity curve (TIC) parameters obtained from transrectal contrast-enhancedultrasound (TR-CEUS) and important pathological prognostic factors in rectal adenocarcinoma. We retrospectively included 477 patients with pathologically confirmed rectal adenocarcinoma. TIC parameters werederived from preoperative dynamic TR-CEUS images. These parameters included peak intensity (PI), time to peak (TTP),mean transit time (MTT), slope (S), and area under the curve (AREA). Pathological prognostic factors included TN stage,tumor diameter, lymphovascular invasion (LVI), perineural invasion, and tumor differentiation. Spearman's correlation analysisand binary logistic regression were used to analyze the association between TIC parameters and pathological prognosticfactors. pT1-2 stages rectal carcinomas exhibited higher PI-max, PI-min, S-max, S-min, AREA-max, and AREA-minthan pT3-4 stages (all p<0.05). pN0 stage rectal adenocarcinomas displayed higher PI-max, S-max, AREA-max, PI-ratio, Sratio,and AREA-ratio than pN1-2 stage (all p<0.05). PI-ratio and S-ratio were higher in the LVI-negative and tumor diameter≥4cm group compared to the LVI-positive and tumor diameter <4cm group, respectively (p<0.05). Well-differentiated rectaladenocarcinomas displayed higher PI-max, AREA-max, PI-ratio, S-ratio, and AREA-ratio than the moderate-poor differentiatedgroup (all p<0.05). PI-max, S-max, AREA-max, PI-ratio, S-ratio, and AREA-ratio were negatively correlated with pNstage (all p<0.05). PI-ratio and S-ratio were independent predictive factors for the pN stage (OR=0.774, OR=1.048). S-ratioand AREA-ratio were independent predictive factors for tumor differentiation (OR=1.071, OR=0.911). TIC parametersderived from TR-CEUS exhibit correlations with specific pathological prognostic factors in rectal adenocarcinomas.This non-invasive method may hold promise for preoperatively assessing the prognosis of rectal adenocarcinoma patients.