Dwell Time Research Articles

Peripherally Inserted Central Venous Catheter-Related Complications in Adult Patients with Haematological Malignancy.

Peripherally inserted central venous catheters (PICC) are widely used in patients with haematological malignancies owing to the requirement for prolonged intravenous therapy. However, the growing use of PICCs has resulted in a multitude of complications such as infections and thrombosis, leading to prolonged hospitalisation periods and increased morbidity. This study aimed to determine the incidence of and factors associated with PICC-related complications in patients with haematological malignancies. This prospective cohort study was conducted at a single academic institution. The inclusion criteria involved all adult patients with haematological malignancies who had newly inserted PICCs. The patients were observed for a minimum duration of 60 days to evaluate the incidence of PICC-related infections and thrombosis, as well as mechanical complications. A total of 119 PICCs were implanted in 85 patients. Among them, more than half of the patients were diagnosed with lymphoma (55.0%). The median dwell time was 61 days (interquartile range: 98 days). The incidence of PICC-related complications was 58.0% (6.9 per 1,000 catheter-days). Specifically, 43 PICCs (36.1%, 4.3 per 1,000 catheter-days) experienced infective complications, 25 (21.1%, 2.5 per 1,000 catheter-days) encountered mechanical complications and 1 (0.8%, 0.1 per 1,000 catheter-days) exhibited thrombotic complications. Furthermore, an underlying diagnosis of acute leukaemia was significantly associated with a higher incidence of PICC-related infections. Our study revealed higher incidence rates of PICC-related complications in adult patients with haematological malignancies compared to the finding of other studies. Notably, patients with underlying acute leukaemia displayed a higher incidence of PICC-related infections. These findings underscore the importance of implementing appropriate interventions and conducting thorough root cause analyses to effectively mitigate this complication and improve patient outcomes.

Mutation in pore-helix modulates interplay between filter gate and Ba2+ block in a Kcv channel pore.

The selectivity filter of K+ channels catalyzes a rapid and highly selective transport of K+ while serving as a gate. To understand the control of this filter gate, we use the pore-only K+ channel KcvNTS in which gating is exclusively determined by the activity of the filter gate. It has been previously shown that a mutation at the C-terminus of the pore-helix (S42T) increases K+ permeability and introduces distinct voltage-dependent and K+-sensitive channel closures at depolarizing voltages. Here, we report that the latter are not generated by intrinsic conformational changes of the filter gate but by a voltage-dependent block caused by nanomolar trace contaminations of Ba2+ in the KCl solution. Channel closures can be alleviated by extreme positive voltages and they can be completely abolished by the high-affinity Ba2+ chelator 18C6TA. By contrast, the same channel closures can be augmented by adding Ba2+ at submicromolar concentrations to the cytosolic buffer. These data suggest that a conservative exchange of Ser for Thr in a crucial position of the filter gate increases the affinity of the filter for Ba2+ by >200-fold at positive voltages. While Ba2+ ions apparently remain only for a short time in the filter-binding sites of the WT channel before passing the pore, they remain much longer in the mutant channel. Our findings suggest that the dwell times of permeating and blocking ions in the filter-binding sites are tightly controlled by interactions between the pore-helix and the selectivity filter.

Precise surface machining of fused silica using high stability atmospheric pressure microwave plasma jet with a new internal electrode

Plasma is a promising approach for machining of fused glass substrates. Developing high-performance microwave torch is the core element to ensure the processing accuracy of this technology. In this study, a spline curve-based microwave torch internal electrode structure was proposed, which increased the internal electric field strength by 54 %. The discharge dynamics simulation based on this electrode shows that the plasma is excited at the inner electrode tip and the bottom of the resonant cavity, then it expands to form a linear discharge region and eventually fill the discharge tube. It was revealed by CCD images that with the increase of carrier gas flow rate, turbulent flow state appears in the tail of the jet. OES data shows that microwave Ar plasma can effectively dissociate CF4, and due to the oxidation effect of oxygen, CFx and C2 content decrease significantly with the addition of oxygen. The machining experiment on fused silica shows that the material removal stability of this torch reaches 3.69 %, and the removal rate increases nYarly with dwell time due to thermal effect. Finally, the machining performance of the atmospheric pressure microwave plasma jet was verified by figuring of a planar fused silica surface reducing the form error from 108.1 nm RMS to 16.5 nm RMS.

Effect of mold dwell time on shrinkage defects in investment casting of superalloy turbine blade

Effect of mold dwell time on shrinkage defects in investment casting of superalloy turbine blade

Stability of impulsive and switched stochastic delay systems via the event-triggered impulsive mechanism

Under the event-triggered impulsive mechanism, this work introduces the pth moment (integral) input-to-state stability (p-(i)ISS) for a general group of impulsive and switched stochastic delay systems. Using the means of mode-dependent average dwell time and mode-dependent average impulsive interval, some sufficient conditions of p-ISS and p-iISS are supplied. By incorporating the input of subsystems and impulses into the triggering functions, two distinct types of event-triggered impulsive constraint is proposed, which is defined as mode-dependent event-triggered impulsive mechanism with input (MDETIMI). Different from the traditional event-triggered impulsive control, two MDETIMI strategy are individually discussed, which one is the supremum of K∞ function of subsystem input and the superposition of impulsive input, and the other is the integral of K∞ function of subsystem input and the superposition of impulsive input. Moreover, it is unveiled that even with the indeterminate derivatives of the Lyapunov functions, the Zeno phenomenon can effectively be avoided by using MDETIMI strategy. Finally, an example shows the effectiveness and practicability of the results.

Out with the old: Single center experience with transvenous extraction of leads older than 15 years.

Lead dwell time is the single strongest predictor of failure and complications in transvenous lead extraction. To report the success rate and complications of transvenous lead extractions with implant dwell time of at least 15 years. Procedural and patient data were prospectively collected into a database. The excimer laser was the primary method for lead extraction with the use of mechanical rotational sheaths and femoral snares at operator discretion. A total of 442 patients between 2011 and 2020 underwent lead extraction (705 leads) primarily for infection or device failure at our high-volume center. Forty-one patients with 71 leads>15 years old were included in this cohort. Mean patient age was 53.5 ± 18.5 years, 67.5% were male. Mean lead dwell time was 19.6 ± 4.4 years. Thirty-six of 41 (88%) patients had successful extraction of all leads compared to 96% in the remaining 401 patients, p value.004. Of the five patients without fully successful extractions two of these patients had abandoned leads (three total) that were clinically significant. There were two (4.9%) major complications in the very old lead group and six (1.5%) in the other group. In the very old lead group, one patient experienced right atrial appendage perforation requiring surgical repair and recovered well. One patient experienced new complete heart block requiring 2 min of CPR but did well thereafter. There was no procedure-related mortality. Despite challenges posed by older leads, very old leads can be safely and effectively extracted with low complication rates.

A probabilistic framework for describing a class of switching signals in continuous-time

We present an interpretation of switching signals with certain average dwell time in terms of Poisson process, which allows to build a probabilistic framework to accommodate all the switching signals of this kind. As a result, we can learn more knowledge about such signals. In particular, such a switching signal and the solution of the corresponding switching system jointly constitute a Markov process. And the Markov property will facilitate the asymptotic behaviour analysis of the switching dynamics. As a byproduct, we present an upper bound on the joint spectral radius of a family of Hurwitz or anti-Hurwitz matrices, which turns out to be quite sharp as compared with the existing results.

Feasibility and utility of a combined nasogastric-tube-and-string-test device for bacteriologic confirmation of pulmonary tuberculosis in young children

For microbiological confirmation of pediatric pulmonary tuberculosis (PTB), gastric aspirates (GA) are often operationally unfeasible without hospitalization, and the encapsulated orogastric string test is not easily swallowed in young children. The Combined-NasoGastric-Tube-and-String-Test (CNGTST) enables dual collection of GA and string specimens. In a prospective cohort study in Kenya, we examined its feasibility in children under five with presumptive PTB and compared the bacteriological yield of string to GA. Paired GA and string samples were successfully collected in 95.6 % (281/294) of children. Mycobacterium tuberculosis was isolated from 7.0 % (38/541) of GA and 4.3 % (23/541) of string samples, diagnosing 8.2 % (23/281) of children using GA and 5.3 % (15/281) using string. The CNGTST was feasible in nearly all children. Yield from string was two-thirds that of GA despite a half-hour median dwelling time. In settings where the feasibility of hospitalisation for GA is uncertain, the string component can be used to confirm PTB.

Lead Break during Extraction: Predisposing Factors and Impact on Procedure Complexity and Outcome: Analysis of 3825 Procedures.

Background: Currently, there are no reports describing lead break (LB) during transvenous lead extraction (TLE). Methods: This study conducted a retrospective analysis of 3825 consecutive TLEs using mechanical sheaths. Results: Fracture of the lead, defined as LB, with a long lead fragment (LF) occurred in 2.48%, LB with a short LF in 1.20%, LB with the tip of the lead in 1.78%, and LB with loss of a free-floating LF in 0.57% of cases. In total, extractions with LB occurred in 6.04% of the cases studied. In cases in which the lead remnant comprises more than the tip only, there was a 50.31% chance of removing the lead fragment in its entirety and an 18.41% chance of significantly reducing its length (to less than 4 cm). Risk factors for LB are similar to those for major complications and increased procedure complexity, including long lead dwell time [OR = 1.018], a higher LV ejection fraction, multiple previous CIED-related procedures, and the extraction of passive fixation leads. The LECOM and LED scores also exhibit a high predictive value. All forms of LB were associated with increased procedure complexity and major complications (9.96 vs. 1.53%). There was no incidence of procedure-related death among such patients, and LB did not affect the survival statistics after TLE. Conclusions: LB during TLE occurs in 6.04% of procedures, and this predictable difficulty increases procedure complexity and the risk of major complications. Thus, the possibility of LB should be taken into account when planning the lead extraction strategy and its associated training.

Guidelines for bus speed at intersections under travel time control

To improve the traffic efficiency of bus at a group of intersections and reduce their delay, this paper develops a speed guidance strategy for buses under travel time control at intersection groups. The approach considers the influence of bus departure time, bus station arrival rate, and bus station dwell time. Simulation experiments are carried out on three consecutive intersections along Jinshan Avenue in Fuzhou, China. Results show that the average travel time of buses, the average delay of buses, and the average delay per capita in the priority direction are reduced by 5.5%, 9.9%, and 9.4%, respectively. The optimal rate of the average number of bus stops reached 15.2%. The indicators of the non-priority direction of social vehicles are not significantly affected. It shows that the efficiency of buses has improved after implementing the speed guidance strategy at the intersection groups without affecting the social vehicles as far as possible.

Influence of bubble size on perfluorooctanesulfonic acid degradation in a pilot scale non-thermal plasma treatment reactor

A 25L working volume non-thermal plasma-based treatment reactor was trialled to destroy per- and polyfluoroalkyl substances (PFAS) utilising argon bubbles to transport PFAS to the surface to be destroyed with plasma interaction at the argon-liquid interface. The breakdown rate of PFAS and the system's overall energy efficiency could be improved while minimising gas usage by utilising small bubbles (0.6–0.7 mm d32) to maximise the transport of PFAS to the plasma discharge for destruction. Vertically scaling the treatment reactor dimensions increases the overall liquid height and dwell time for bubbles to contact and transport PFAS molecules to the surface. The removal rate of perfluorooctane sulfonate (PFOS) correlated with the total surface area of the gas. Significant concentration gradients of PFOS could be observed when sampling from different liquid heights within the 25 L reactor. A one-dimensional model of mass transfer to the surface of rising bubbles was developed and gave good predictions of the overall rates of PFOS breakdown with modelled time constants of 0.14–0.18 min−1 versus 0.16 ± 0.01 min−1 for the fine bubble diffuser, and 0.048–0.053 min−1 versus 0.06 min−1 for the medium bubble diffuser. The time constant compared favourably with similar experiments at the 2 L scale of 0.11 min−1.

The Influence of Competing Social and Symbolic Cues on Observers' Gaze Behaviour.

The effects of social (eye gaze, pointing gestures) and symbolic (arrows) cues on observers' attention are often studied by presenting such cues in isolation and at fixation. Here, we extend this work by embedding cues in natural scenes. Participants were presented with a single cue (Experiment 1) or a combination of cues (Experiment 2) embedded in natural scenes and were asked to 'simply look at the images' while their eye movements were recorded to assess the effects of the cues on (overt) attention. Single-gaze and pointing cues were fixated for longer than arrows but at the cost of shorter dwell times on the cued object. When presented together, gaze and pointing cues were fixated faster and for longer than simultaneously presented arrows. Attention to the cued object depended on the combination of cues and whether both cues were directed towards or away from the target object. Together, the findings confirm earlier observations that people attract attention more strongly than arrows but that arrows more strongly direct attention.

Dwell Times, Wavepacket Dynamics, and Quantum Trajectories for Particles with Spin 1/2.

The theoretical connections between quantum trajectories and quantum dwell times, previously explored in the context of 1D time-independent stationary scattering applications, are here generalized for multidimensional time-dependent wavepacket applications for particles with spin 1/2. In addition to dwell times, trajectory-based dwell time distributions are also developed, and compared with previous distributions based on the dwell time operator and the flux-flux correlation function. Dwell time distributions are of interest, in part because they may be of experimental relevance. In addition to standard unipolar quantum trajectories, bipolar quantum trajectories are also considered, and found to relate more directly to the dwell time (and other quantum time) quantities of greatest relevance for scattering applications. Detailed calculations are performed for a benchmark 3D spin-1/2 particle application, considered previously in the context of computing quantum arrival times.

H∞ attenuation of disturbance switching over multiple frequency ranges

SummaryThis paper addresses the problem of switching control for systems subject to external disturbances that vary over multiple frequency ranges. Specifically, two different scenarios of disturbance injection are considered; namely, the disturbance may switch between different prescribed frequency ranges, subject to an average dwell time setting, or the disturbance may reside within one of the frequency ranges. To address these scenarios, a disturbance‐triggered control scheme is developed that divides the entire frequency range into low‐, mid‐, and high‐frequency ranges. This scheme ensures closed‐loop stability under average dwell time frequency‐range switching and achieves performance when operated under individual frequency ranges. Synthesis conditions in matrix inequalities are derived to characterize the switching control, and an iterative algorithm is proposed for finding a desired set of controller gains. Finally, two examples are presented to illustrate the effectiveness of the proposed control method.

Enhancing surface integrity in friction stir welding through deep rolling and post-weld heat treatment

This study aimed to investigate mechanical surface treatment through deep rolling (DR) and post-weld heat treatment (PWHT) to enhance the surface integrity of an AA7075-T651 aluminum alloy welded through friction stir welding (FSW). The surface integrity of the welded joint was evaluated by analyzing residual stress, microhardness, surface roughness, microstructure, and fatigue life. The experimental design comprised three sets: one set exclusively applied FSW, another set applied FSW followed by DR (FSW-DR), and the last set applied FSW followed by PWHT (FSW-PWHT). Fatigue testing (screening) was performed through a four-point bending test with a bending stress of approximately 300 MPa, test frequency of 2.5 Hz at room temperature, and stress ratio (R) of 0. The FSW parameters included a tool rotational speed of 1600 rpm, welding speed of 30 mm/min, immersion depth of 0.1 mm, dwell time of 15 s, and tool tilt angle of 0°. The DR parameters included a rolling pressure of 150 bar and rolling speed of 1400 mm/min. The results revealed that the residual stress significantly influenced fatigue life. The fatigue test demonstrated that FSW workpieces treated with the DR process (FSW-DR) exhibited the highest fatigue life, showing a remarkable increase of 33.5 % compared with that of untreated FSW workpieces. Moreover, the residual stress changed from tensile to compressive, accompanied by noticeable enhancements in microhardness and surface roughness. These results highlight that FSW followed by the DR process (FSW-DR) positively affects weld surface integrity, resulting in an extended service life for welded components.

Extended constant life diagrams for low cycle fatigue and creep-fatigue assessments of high-temperature structures

Over the decades, the constant life diagram has become an important tool for engineering design and assessment. For specific materials, the effect of mean stress and stress amplitude on the fatigue life is considered in traditional constant life diagrams. In this study, the concept of the structural constant creep-fatigue life diagram is proposed for engineering structures subjected to cyclic loads in high-temperature environments. By integrating constant fatigue and creep-fatigue life curves into the traditional Bree diagram, we offer an efficient and reliable approach that enables quick determination of structural life and corresponding failure mechanisms. To provide a one-stop solution for the evaluation of constant fatigue/creep-fatigue life curves, an extended Unified Procedure for Fatigue and Ratchet Analysis (eUPFRA) has been proposed based on the Linear Matching Method (LMM) framework. Case studies on engineering components have also been performed with consideration of the cyclic hardening effect, temperature-dependent material properties and various damage models. The impact of the target life and creep dwell time is further investigated, as well as the creep-fatigue interaction mechanism. Verification against ABAQUS step-by-step inelastic analysis has finally been conducted, confirming the precision and efficiency of the eUPFRA.

Electron Probe Microanalysis of Trace Sulfur in Basaltic Glasses and Silicate Minerals

Abstract Sulfur (S) in the mantle is conventionally assumed to be exclusively stored in accessory sulfide phases, but recent work shows that the major silicate minerals that comprise >99% of the mantle could be capable of hosting trace amounts of S. Assessing the incorporation of trace S in nominally S-free mantle minerals and determining equilibrium S partitioning between these minerals and basaltic melt requires analyzing small experimental phases with low S contents. Here, we develop a protocol for EPMA analysis of the trace levels of S in silicate phases. We use a suite of natural and experimental basaltic glass primary and secondary standards with S contents ranging from 44 ppm to 1.5 wt.%. The effects of beam current and counting time are assessed by applying currents ranging from 50 to 200 nA and total counting times between 200 and 300 seconds at 15 kV accelerating voltage. We find that the combination of 200 nA beam current with a 200 second counting time (80 second peak, 60 seconds each for upper and lower background, respectively) achieves precise yet cost-effective measurements of S down to a calculated detection limit of ~5 ppm and a blank-derived, effective detection limit of ~17 ppm. Close monitoring of the S peak intensity and position throughout the duration of each spot also shows that high currents and extended dwell times do not compromise the accuracy of measurements, and even low S contents of 44 ppm can be reproduced to within one standard deviation. Using our developed recipe, we analyzed a small suite of experimental clinopyroxenes (cpx) and garnets (gt) from assemblages of silicate partial melt + cpx ± gt ± sulfide, generated at 1.5 to 3.0 GPa and 1200 to 1300 °C. We find S contents of up to 71 ± 35 ppm in cpx and 63 ± 28 ppm in gt, and calculate mineral-melt partition coefficients (Dsmin/melt) of up to 0.095 ± 0.064 and 0.110 ± 0.064 for Dscpx/melt and Dsgt/melt, respectively. The sulfur capacity and mineral-partitioning for cpx are in good agreement with SXRF measurements in a prior study by Callegaro et al. (2020), serving as an independent validation of our EPMA analytical protocol.

Improved input‐to‐state stability criteria for time‐varying switched singular systems

AbstractThis paper is dedicated to proposing improved input‐to‐state stability (ISS) criteria for a class of continuous‐time time‐varying switched singular systems (CTSSS) under slow/fast/slow‐fast switching signals. Specifically, for a CTSSS with time‐varying singular matrices, the authors start with an improved sufficient condition for verifying its ISS under slow switching signals based on the average dwell time method and a relaxed multiple Lyapunov function. Then, considering several or all subsystems may destroy the overall ISS, relaxed sufficient conditions are presented to ensure the ISS of the CTSSS under fast switching signals and slow‐fast switching signals, respectively. Note that the improvement of the proposed ISS criteria is embodied in the derivative of the required multiple Lyapunov functions along with the state trajectories of CTSSS can be positive or negative. Finally, three numerical examples are provided to illustrate the feasibility of the obtained results.

Anhedonia reflects an encoding deficit for pleasant stimuli in schizophrenia: Evidence from the emotion-induced memory trade-off eye-tracking paradigm.

The present study explored the hypothesis that anhedonia reflects an emotional memory impairment for pleasant stimuli, rather than diminished hedonic capacity in individuals with schizophrenia (SZ). Participants included 30 SZ and 30 healthy controls (HCs) subjects who completed an eye-tracking emotion-induced memory trade-off task where contextually relevant pleasant, unpleasant, or neutral items were inserted into the foreground of neutral background scenes. Passive viewing and poststimulus elaboration blocks were administered to assess differential encoding mechanisms, and immediate and 1-week recognition testing phases were completed to assess the effects of delay interval. Participants also made self-reports of positive emotion, negative emotion, and arousal in response to the stimuli. Results indicated that SZ experienced stimuli similarly to HC. Both groups demonstrated the typical emotion-induced memory trade-off during the passive viewing and poststimulus elaboration encoding blocks, as indicated by more hits for emotional than neutral items and fewer hits for backgrounds paired with emotional than neutral items. Eye-tracking data also indicated that both groups were more likely to fixate earlier and have longer dwell time on emotional than neutral items. At the 1-week delay, the emotion-induced memory trade-off was eliminated in both groups, and SZ showed fewer overall hits across valence conditions. Greater severity of anhedonia was specifically associated with impaired recognition for pleasant stimuli at the immediate recognition phase. Findings suggest that anhedonia in SZ is associated with emotional memory impairment, particularly a deficit in encoding positive stimuli. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Pressure–temperature–time controls on shock vein formation within the Steen River impact structure

ABSTRACTThermodynamic modeling has been applied to determine pressure–temperature–time conditions leading to shock vein formation during the passage of a natural shock wave generated by hypervelocity impact. The approach is novel in considering both shock front and rarefaction pressures, as well as simultaneously forming and cooling the shock veins via two‐dimensional steady‐state conduction. Model results are tested using shock veins developed in granitic rocks that constitute the central uplift of the Steen River impact structure in Canada. Here, two variants of majoritic garnet were generated in different settings: (1) along the margins of shock veins due to pargasite and biotite breakdown (accompanied by maskelynite formation), and (2) within the originally molten shock vein matrix as newly grown crystals. We determine that during shock vein formation, the shock front pressure and wave width at the reconstructed sample location were 18 GPa and 830 m, respectively, with a dwell time of 160 ms. Intra‐vein melting at 2150°C was attained within 1 μs. Melt cooled to the solidus in 150 ms following shock front passage. Majoritic garnet formation was facilitated by the high temperatures realized within the veins as a result of frictional melting that accompanied shock loading. The calculated pressure–temperature–time (P–T–t) path provides constraints on the formation conditions of majoritic garnet at Steen River. The model results independently support previously determined P–T conditions based on mineral stability fields. The vein margin garnets (35–39 mole% majorite) and maskelynite formed first under higher P–T conditions for a longer duration (36 ms). The matrix garnets (11–22 mole% majorite) crystallized from melt under lower P–T conditions and for a shorter duration (22 ms). Our results indicate that shock pressure alone should not be used as a basis for shock classification. Instead, the interplay between pressure and temperature with time and the duration of shock immersion (dwell) must be considered.