Dwell Time Research Articles

Safety of long-term esophageal stent use for multiple indications.

Long-term (>30 days) esophageal stenting is controversial. Previous studies have documented complications associated with long-term esophageal stent use. This study's objective was to investigate complications associated with long-term esophageal stent use. A retrospective review of stenting done by thoracic surgery for any reason between 2010-2020 was completed. Patients were included if they had at least 30 days of follow-up after their initial stent placement. Outcomes included stent dwell time, patient outcomes, procedural and stent-related complications. Fifty-six patients, with 25 having ≥2 stents placed were included; overall, 90 stents were placed. The median length of initial esophageal stent dwell time was 59 [interquartile range (IQR), 21-119] days. Stent migration was the most common complication and occurred more with benign indications (P=0.12). As the length of dwell time increased, prevalence of any complication decreased. Complication rates between short-term (<30 days) and long-term stents were not significantly different (P=0.39). No instances of esophageal perforation or aortoesophageal fistulas related to stents were identified. There was one instance of post-esophagectomy tracheoesophageal fistula which was managed successfully with prolonged stenting. Over a 10-year period, there were no instances of stent erosion into the aorta or esophageal perforation, and the most frequent stent-related complication was stent migration. Long-term esophageal stenting did not result in increased rates of stent related complications in our cohort. This case series demonstrates that long-term stents may be safely used for many different indications. Randomized controlled studies may be needed to validate these findings.

Creep–fatigue life prediction of a titanium alloy deep-sea submersible using a continuum damage mechanics-informed BP neural network model

Deep-sea submersibles are subjected to trapezoidal wave loading during operation, which can cause creep–fatigue failure of pressure hull structures. To ensure structural safety, it is necessary to develop accurate and efficient creep–fatigue life prediction methods. This paper proposes a continuum damage mechanics-informed BPNN approach for predicting the creep–fatigue life of titanium alloy submersibles. To obtain a reliable sample set, the creep–fatigue life is calculated based on the titanium alloy room-temperature creep–fatigue damage model and numerical analysis methods proposed by the authors. The operating duration, operating pressure, axial stress, and circumferential stress were selected as the input variables, whereas the number of cycles and actual operating duration were chosen as the output variables. The proposed model fills the current gap of a lack of research on the creep‒fatigue life prediction of titanium alloy deep-sea submersibles via machine learning methods. The research results show that the neural network model established in this paper can quickly and accurately predict the creep–fatigue life of titanium alloy deep-sea submersibles. A sensitivity analysis of the input parameters revealed that the creep–fatigue life is more sensitive to the operational pressure than to the dwell time.

Critical Analysis of Inter-layer Dwell Time on the Properties of Wire Arc Additive Manufactured Steel Structure: Experimental and Modelling Approach

Critical Analysis of Inter-layer Dwell Time on the Properties of Wire Arc Additive Manufactured Steel Structure: Experimental and Modelling Approach

Effect of Augmented Reality (AR) and Virtual Reality (VR) experiences on customer engagement and purchase behavior in retail stores

This review paper explores the impact of Augmented Reality (AR) and Virtual Reality (VR) technologies on customer engagement and purchasing behavior in retail settings. As immersive technologies continue to evolve, AR and VR are increasingly employed to enhance the shopping experience, offering interactive and personalized engagements that traditional retail cannot match. Through a comprehensive analysis of recent literature, the paper highlights how AR applications, such as virtual try-ons and interactive product displays, significantly enhance customer engagement by providing novel and enriched shopping experiences. Similarly, VR facilitates virtual store visits and immersive product interactions, leading to higher levels of customer satisfaction and brand loyalty. The paper discusses key metrics for evaluating engagement and purchase behavior changes, including increased dwell time, higher conversion rates, and enhanced customer satisfaction. Additionally, the review identifies challenges, such as technological integration and user adaptation, which may impede the full potential of AR and VR in retail. The findings underscore the transformative potential of AR and VR in reshaping the retail landscape by bridging the gap between digital and physical shopping environments, thus driving more informed purchasing decisions and fostering deeper customer connections. Future research directions are suggested to address the limitations and further investigate the long-term impacts of these technologies on consumer behavior.

The role of depth of general anesthesia in serum CGRP and SP level in diabetes patients.

Diabetes, which is associated with cardiovascular disease and related microvascular complications, affects life expectancy and decrease quality of life. A trial reports that the risk of patients with diabetes having cardiovascular disease is 2-4 times compared with that in patients without diabetes. This study aims to investigate the relationship between depth of general anesthesia in patients with diabetes mellitus. This clinical study totally includes 40 patients with diabetes mellitus, and these patients are divided into following two groups: diabetes mellitus deep anesthesia group and diabetes mellitus light anesthesia group, and then these patients receive general anesthesia combined with laparoscopic surgery. Preoperative patient general data and intraoperative patient general data are collected and analyzed. Calcitonin gene-related peptide (CGRP) and substance P (SP) level are determined by Enzyme-linked immunosorbent assay (ELISA). This study included a total of 40 patients. There were no significant differences in demographic and preoperative patient general data between the two groups. Measurements were taken for operative time, anesthesia time, recovery time after drug withdrawal, dwell time in the recovery room, intraoperative fluid volume, intraoperative blood loss, and intraoperative urine output between the two groups. Significant differences were observed in the recovery time after drug withdrawal between the two groups. CGRP and SP level in diabetes mellitus deep anesthesia group are evidently more than those in diabetes mellitus light anesthesia group. CGRP and SP level are involved in the diabetes mellitus and up-regulated CGRP and SP can prevent the development of diabetes mellitus. Our study extends the existing literature by addressing a gap in knowledge regarding the impact of anesthesia depth on neuropeptide levels in diabetes mellitus patients. By delineating this relationship, we aim to contribute to the advancement of perioperative care practices and ultimately improve outcomes for individuals with diabetes undergoing surgical procedures. Our study's findings provide valuable insights into the complex interactions between anesthesia, neuropeptides, and diabetes mellitus, offering the potential for personalized perioperative care, enhanced pain management, and improved surgical outcomes. These implications highlight the clinical relevance of our research and its potential to inform future advancements in perioperative care for diabetic patients undergoing surgery.

Design update of DEMO BOP for HCPB BB concept with an energy storage system

An option for the Intermediate Coupling Design (ICD) of the European Demonstration Fusion Reactor (DEMO) Balance of Plant (BOP) configuration for Helium-Cooled Pebble Bed (HCPB) Breeding Blanket (BB) concept consists of the Primary Heat Transport System (PHTS), the Intermediate Heat Transfer System (IHTS), using HITEC salt as coolant, equipped with a thermal Energy Storage System (ESS), and the Power Conversion System (PCS). The aforementioned BOP configuration is capable of producing electricity continuously during the pulse time (2 h) and dwell time (10 min) of DEMO plant operation.The present study reports on the current (2023) thermal system design of DEMO HCPB ICD BOP for 12 operational states defined by the DEMO Design Central Team (DCT) in 2021. It was shown that the PCS is able to accommodate all of the 12 operational points defined based on the uncertainties of the energy map, provided that an additional bypass line at the outlet of the Divertor Cassettes (DIV-CAS) Heat Exchanger (HX) towards the low-pressure part of the feedwater line (to the condenser in this investigation) is installed in the system. This line is activated only in the cases, where the feedwater flow to the low temperature DEMO heat sources HXs is needed to be higher than that necessary to remove BB power at the Steam Generators (SGs). In all the other cases, the bypass line remains unused. Additionally, perspective improvements of DEMO HCPB BOP regarding thermal ESS, as well as PCS are discussed.

Creep-fatigue behavior of thermal barrier coated single-crystal nickel-based superalloys

Thermal barrier coatings (TBCs) reduce the surface temperature of superalloy components but may affect the mechanical properties of the substrate. This study investigates the creep-fatigue behavior of TBC-coated single-crystal superalloys under 1 s, 60 s, and 180 s dwell times. The results indicate that TBCs are beneficial at a 1 s dwell time. The comparison of fracture morphology between coated and uncoated samples showed no change in the failure mechanism due to TBCs under creep-fatigue loading. A creep-fatigue lifetime prediction method based on continuous damage mechanics was also proposed. The predicted results were all within a double dispersion coefficient, showing good agreement with the experimental results. This study provides insights into the durability of TBC-coated single-crystal superalloys under creep-fatigue loading.

Absolute stability for switched Lurie systems with all unstable subsystems

This paper addresses the issue of absolute stability in switched Lurie systems, where each subsystem is individually unstable. By introducing the discretized time-varying Lyapunov function method, sufficient conditions are presented that ensure all system solutions converge to zero. Furthermore, algorithms based on the binary search method are proposed to determine the upper and lower bounds of admissible dwell time, which reveal a larger stable region compared to the existing ones. Finally, two numerical examples illustrate the validity of our results.

The Inferior Vena Cava Filter Placement Parameters May Predict Filter Retrieval Outcomes

ObjectiveWe aimed to investigate the potential correlation between the placement factors of various retrievable inferior vena cava filters and retrieval outcomes. Additionally, we aimed to identify the factors affecting the placement tilt of the filter. Materials and methodsThis retrospective study was conducted at a tertiary care center to investigate patients who had previously undergone retrievable filter placement at our center and who subsequently had their filters removed between January 2020 and December 2021. Patient characteristics and filter-related factors were recorded. Complex filter retrieval was defined as cases that required a minimum of 8 minutes of fluoroscopy or that involved advanced techniques. Regression models were used to explore patient- and placement procedure-related factors that could influence retrieval outcomes and the placement tilt angle. ResultsThe study included 163 patients, and all filters were successfully retrieved. Thirty-seven (22.7%) retrievals were classified as complex retrievals. The mean diameter of the inferior vena cava in the preplacement position for the entire cohort was 16 ± 1.8 mm. The median filter tilt angles at placement and retrieval were 5.0° (IQR, 1.8°- 9°) and 4.6° (IQR, 2.1°-8.0°), respectively. The placement tilt angle was not significantly associated with complex retrieval (p=0.59). The filter hook abutment to the vena cava wall (OR, 10.76, p = 0.003), dwell time (OR, 1.02, p =0.029), and diameter of the vena cava (OR, 10.21, p < 0.001) were associated with complex retrieval. The diameter (p=0.049), age (p=0.049), and filter brand (p=0.001) were found to be significantly associated with placement tilt. ConclusionsThe inferior vena cava diameter at the time of placement predicts difficulty in filter retrieval. In addition, the filter hook abutting the IVC wall and long indwelling time may complicate retrieval. The vena cava diameter is also closely related to the degree of filter tilt.

Superluminality in parity-time symmetric Bragg gratings

Parity-time ( PT ) symmetric Bragg gratings (PTBGs) possess unique features compared to traditional ones. For example, the photonic bandgap of a PTBG can be modified and even closed when the PT symmetry evolves from an exact phase to a broken one, and the complex reflection coefficient of a PTBG is sensitive to the direction of incidence. In this article, we reveal how the superluminal effects of transmission behave following the modified band structure of PTBGs. The superluminality of the directionally sensitive reflection is also discussed. We then investigate the Hartman effect and argue that, to account for the superluminal effects in PTBGs, a directionally sensitive dwell time should be applied. This study offers unique insights into the mechanisms of superluminality and group delay of light in non-Hermitian open systems and contributes to the advancement of PTBGs, which can eventually become an indispensable platform for probing some of the exotic properties of optical wave phenomena and light–matter interactions.

H∞ control of delayed switched systems under asynchronous switching: New results without the constraint between the switching delay and the dwell time of submodes

AbstractThis article investigates the control problem of switched systems with time‐varying delays under asynchronous switching. By reconstructing the switching rule of local controllers and empolying multiple Lyapunov functionals and integral inequalities, sufficient conditions without the constraint between the switching delay and the dwell time of submodes to solve the control problem are derived. The control gain matrices can be conveniently obtained by the proposed linear search algorithm.

Altered static and dynamic functional network connectivity in individuals with subthreshold depression: a large-scale resting-state fMRI study.

Dynamic functional network connectivity (dFNC) is an expansion of static FNC (sFNC) that reflects connectivity variations among brain networks. This study aimed to investigate changes in sFNC and dFNC strength and temporal properties in individuals with subthreshold depression (StD). Forty-two individuals with subthreshold depression and 38 healthy controls (HCs) were included in this study. Group independent component analysis (GICA) was used to determine target resting-state networks, namely, executive control network (ECN), default mode network (DMN), sensorimotor network (SMN) and dorsal attentional network (DAN). Sliding window and k-means clustering analyses were used to identify dFNC patterns and temporal properties in each subject. We compared sFNC and dFNC differences between the StD and HCs groups. Relationships between changes in FNC strength, temporal properties, and neurophysiological score were evaluated by Spearman's correlation analysis. The sFNC analysis revealed decreased FNC strength in StD individuals, including the DMN-CEN, DMN-SMN, SMN-CEN, and SMN-DAN. In the dFNC analysis, 4 reoccurring FNC patterns were identified. Compared to HCs, individuals with StD had increased mean dwell time and fraction time in a weakly connected state (state 4), which is associated with self-focused thinking status. In addition, the StD group demonstrated decreased dFNC strength between the DMN-DAN in state 2. sFNC strength (DMN-ECN) and temporal properties were correlated with HAMD-17 score in StD individuals (all p < 0.01). Our study provides new evidence on aberrant time-varying brain activity and large-scale network interaction disruptions in StD individuals, which may provide novel insight to better understand the underlying neuropathological mechanisms.

Dwell time and spin polarization for electron in single ferromagnetic-stripe device modulated by spin–orbit couplings

Considering both Zeeman effect and spin–orbit coupling, we calculate dwell time for electron in single ferromagnetic-stripe device (SFSD), which can be constructed by patterning a nanosized ferromagnetic stripe on the surface of GaAs/AlxGa1-xAs heterostructure. Due to an intrinsic symmetry in the SFSD, dwell time is independent of electron spins, if only Zeeman effect is involved. However, the intrinsic symmetry is broken by spin–orbit coupling, which gives rise to spin-dependent dwell time for electron in the SFSD. As a result, electron spins can be separated in time dimension, which induces an obvious electron-spin polarization effect in the SFSD. Spin polarization ratio can be efficaciously modified by interfacial confining electric-field or strain engineering, which attributes to the dependence of effective potential felt by electron in the SFSD on spin–orbit couplings. Thus, the SFSD can act as a controllable temporal electron-spin splitter, a class of electron-spin polarized sources in semiconductor spintronics.

Stabilization of aperiodic sampled-data switched affine systems to hybrid limit cycles

This paper deals with the stabilization of aperiodic sampled-data switched affine systems to a predetermined hybrid limit cycle using a hybrid dynamical system representation and a control Lyapunov function approach. Some preliminaries on the hybrid dynamical system formalism provide the framework for modeling switched affine systems followed by definitions on hybrid limit cycles and related notions. The main result, based on simple Linear Matrix Inequalities (LMI), guarantees that the solutions to the closed-loop system converge to a hybrid limit cycle defined by the states, functioning modes with their corresponding dwell times. The theoretical results are evaluated on academic examples and demonstrate the potential and the originality of the method over the recent literature.

Crystalline‐amorphous dual‐phase ceramic nanocomposites regulated by entropy engineering

AbstractSolid‐state reaction (SSR) is frequently used to fabricate bulk high‐entropy ceramics (HECs). However, a high temperature and a long dwelling time are typically required to allow the occurrence of SSR. Meanwhile, conventional HECs were typically composed of single‐phase solid solution with micrograins. It is of great interest to develop nanocrystalline dual‐phase HECs under mild conditions. Here, we fabricated entropy‐mediated crystalline‐amorphous dual‐phase ceramic nanocomposites, and the fabrication process showed significantly higher energy and time efficiency than the conventional SSR. The nanocomposites were composed of entropy‐mediated nanoparticles (EM‐NPs) embedded in an amorphous SiO2 matrix. The constituent elements were homogeneously distributed in the EM‐NPs at the atomic level. The EM‐NPs were dislocations‐free but with lattice strain, and they showed a strong coarsening tendency during annealing. The nanocomposites showed a significant solid solution hardening effect. The reported results would provide useful guidance to fabricate nanocrystalline HECs with crystalline‐amorphous dual‐phase microstructure.

Stability of highly nonlinear stochastic systems with non-random switching signals and multiple delays

The situation of multiple delays often occur in hybrid stochastic systems. In this paper, multiple time-varying delays are considered for highly nonlinear switching stochastic systems. The function of time-varying delays is differentiable, and its derivative is a positive constant less than 1. By the Lyapunov functional method and the mode-dependent average dwell time approach, existence and uniqueness of solution, asymptotic stability and pth moment exponential stability for highly nonlinear switching stochastic multiple delays systems are obtained. Finally, an example is afforded to explicate the effectiveness our theoretical analysis results.

Peripheral intravenous catheter-induced phlebitis in a tertiary hospital of Karachi: a cohort study.

This study aimed to determine the incidence of peripheral intravenous catheter (PIVC)-induced phlebitis and its predictors among adult patients hospitalized at Dow University Hospital, Karachi, Pakistan. A sample of 258 adult patients admitted in the selected wards and planned for peripheral intravenous catheter insertion were recruited through consecutive sampling during March to May 2019. Daily follow-ups were performed to observe signs of phlebitis using a validated tool. The cohort was followed until discharge, removal of peripheral intravenous catheter, or study conclusion. Of 258 patients studied, 139 (53.9%) were females. A significant number of the participants 104 (40.3%) were young adults of age 20-40 years. The incidence of phlebitis was 39.1%. Tuberculosis (TB), peripheral intravenous catheter dwell time before initial assessment, administration of IV fluids, and dissatisfactory nursing care at Day 1 were associated significantly with the development of phlebitis. There was a doseresponse relationship between the catheter dwell time in hours before initial assessment and the development of phlebitis. This study found an increased incidence (39.1%) in three months of PIVC-induced phlebitis among adult patients. In addition to patient-related and PIVC-related risk factors considered in this study, PIVC-induced phlebitis is found to be significantly associated with the level of PIVC care provided by nurses. Continuous nursing education, developing standard care plans for PIVCs, and proper documentation of care are recommended.

Pre-Sealing of Endodontic Access Cavities for the Preservation of Anterior Teeth Fracture Resistance.

Sodium hypochlorite solution (NaOCl) is an effective canal irrigant but interferes with the mechanical features of dentin and the bonding capability of adhesives when restoring endodontically treated teeth. This study evaluated whether access cavity resin sealing before using canal irrigant would augment the resistance of endodontically treated anterior teeth against fracture. Sixty maxillary incisors underwent endodontic treatment in five groups (n = 12). Irrigation with 5.25% NaOCl and 17% ethylenediaminetetraacetic acid (EDTA) was performed in all groups except for Group 5. After root canal obturation, in Group 1, the access cavity was kept unrestored. In Group 2, immediate restoration after obturation was achieved. For Group 3, delayed restoration after 1 week was provided. In Group 4 (pre-sealed), before canal irrigation, the dentin surface of access cavities was sealed using self-adhesive composite resin (Vertise Flow) and then restored after obturation. In Group 5, which was saline irrigated, immediate restoration was performed. After storage and thermal cycling for 5000 cycles at 5°C-55°C with a dwell time of 15 s and a transfer time of 5 s, teeth were statically loaded by a universal testing machine until a fracture occurred. Data were collected as the fracture resistance (FR) and analyzed using the one-way analysis of variance and Tukey's tests. FR significantly differed between all groups (p < 0.001). The lowest FR was recorded in the unrestored group (284 ± 86 N), which was not statistically different from the immediately restored group (p = 0.065). The pre-sealed group exhibited the highest FR value (810 ± 127 N, p ≤ 0.02 vs. other groups). The FR of the saline-irrigated and delayed restored groups was almost similar (p = 0.13). NaOCl/EDTA irrigation resulted in an adverse effect on FR. Delayed restoration could reduce this adverse effect. Access cavity pre-sealing with flowable composites led to a higher FR than conventional methods and may be considered an effective step during treatment procedures.

Dynamic functional network connectivity in patients with a mismatch between white matter hyperintensity and cognitive function.

White matter hyperintensity (WMH) in patients with cerebral small vessel disease (CSVD) is strongly associated with cognitive impairment. However, the severity of WMH does not coincide fully with cognitive impairment. This study aims to explore the differences in the dynamic functional network connectivity (dFNC) of WMH with cognitively matched and mismatched patients, to better understand the underlying mechanisms from a quantitative perspective. The resting-state functional magnetic resonance imaging (rs-fMRI) and cognitive function scale assessment of the patients were acquired. Preprocessing of the rs-fMRI data was performed, and this was followed by dFNC analysis to obtain the dFNC metrics. Compared the dFNC and dFNC metrics within different states between mismatch and match group, we analyzed the correlation between dFNC metrics and cognitive function. Finally, to analyze the reasons for the differences between the mismatch and match groups, the CSVD imaging features of each patient were quantified with the assistance of the uAI Discover system. The 149 CSVD patients included 20 cases of "Type I mismatch," 51 cases of Type I match, 38 cases of "Type II mismatch," and 40 cases of "Type II match." Using dFNC analysis, we found that the fraction time (FT) and mean dwell time (MDT) of State 2 differed significantly between "Type I match" and "Type I mismatch"; the FT of States 1 and 4 differed significantly between "Type II match" and "Type II mismatch." Correlation analysis revealed that dFNC metrics in CSVD patients correlated with executive function and information processing speed among the various cognitive functions. Through quantitative analysis, we found that the number of perivascular spaces and bilateral medial temporal lobe atrophy (MTA) scores differed significantly between "Type I match" and "Type I mismatch," while the left MTA score differed between "Type II match" and "Type II mismatch." Different mechanisms were implicated in these two types of mismatch: Type I affected higher-order networks, and may be related to the number of perivascular spaces and brain atrophy, whereas Type II affected the primary networks, and may be related to brain atrophy and the years of education.

Imbalanced temporal states of cortical blood-oxygen-level-dependent signal variability during rest in episodic migraine

BackgroundMigraine has been associated with functional brain changes including altered connectivity and activity both during and between headache attacks. Recent studies established that the variability of the blood-oxygen-level-dependent (BOLD) signal is an important attribute of brain activity, which has so far been understudied in migraine. In this study, we investigate how time-varying measures of BOLD variability change interictally in episodic migraine patients.MethodsTwo independent resting state functional MRI datasets acquired on 3T (discovery cohort) and 1.5T MRI scanners (replication cohort) including 99 episodic migraine patients (n3T = 42, n1.5T=57) and 78 healthy controls (n3T = 46, n1.5T=32) were analyzed in this cross-sectional study. A framework using time-varying measures of BOLD variability was applied to derive BOLD variability states. Descriptors of BOLD variability states such as dwell time and fractional occupancy were calculated, then compared between migraine patients and healthy controls using Mann-Whitney U-tests. Spearman’s rank correlation was calculated to test associations with clinical parameters.ResultsResting-state activity was characterized by states of high and low BOLD signal variability. Migraine patients in the discovery cohort spent more time in the low variability state (mean dwell time: p = 0.014, median dwell time: p = 0.022, maximum dwell time: p = 0.013, fractional occupancy: p = 0.013) and less time in the high variability state (mean dwell time: p = 0.021, median dwell time: p = 0.021, maximum dwell time: p = 0.025, fractional occupancy: p = 0.013). Higher uptime of the low variability state was associated with greater disability as measured by MIDAS scores (maximum dwell time: R = 0.45, p = 0.007; fractional occupancy: R = 0.36, p = 0.035). Similar results were observed in the replication cohort.ConclusionEpisodic migraine patients spend more time in a state of low BOLD variability during rest in headache-free periods, which is associated with greater disability. BOLD variability states show potential as a replicable functional imaging marker in episodic migraine.