Search Results (1,307)

Background/Objectives: Early postoperative hypotony and complications like choroidal detachment can occur after Preserflo MicroShunt (MS) implantation in patients with pseudoexfoliation glaucoma (PEXG). To prevent these risks, outflow from the microshunt tube can be reduced by implementing a nylon stent. This study aims to evaluate the impact of intraluminal stenting of the MS during the first four months after surgery. Methods: This retrospective study of 43 eyes investigated the incidence of intraocular hypotony in PEXG patients undergoing MS implantation with (n = 23) or without (n = 20) intraluminal stenting using a 10.0 nylon suture. The follow-up period was four months after surgery. Results: Our results demonstrated that intraluminal stenting significantly reduced the incidence of postoperative complications related to hypotony. Notably, no cases of choroidal detachment occurred in the nylon-stenting group (nsMS) compared to 30% (6 eyes) in the MS-only group (p = 0.0064). The hypotony rates between the nsMS (21.74%, 5 eyes) and the MS-only group (40%, 8 eyes) did not significantly differ (p = 0.3184). Both groups experienced significant reductions in intraocular pressure (p < 0.001) and a decrease in the number of antiglaucomatous medications (p < 0.001) up to four months after surgery. Conclusions: The use of an intraluminal stent (10.0 nylon suture) during MS implantation may be a promising strategy to reduce the risk of hypotony-related complications, particularly choroidal detachment, in patients with PEXG. Full article

Accurate and reliable characterization of current transformer (CT) performance is essential for maintaining grid stability and power quality in modern electrical networks. CT measurements are key to effective monitoring of harmonic distortions, supporting regulatory compliance and ensuring the safe operation of the grid. This paper addresses a method for the characterization of CTs across an extended frequency range from 50 Hz up to 150 kHz, driven by increasing power quality issues introduced by renewable energy installations and non-linear loads. Traditional CT calibration approaches involve measurement setups that offer ppm-level uncertainty but are complex to operate and limited in practical frequency range. To simplify and expand calibration capabilities, a calibration system employing a sampling ammeter (power analyzer) was developed, enabling the direct measurement of CT secondary currents of an unknown CT and a reference CT without any further auxiliary equipment. The resulting expanded magnitude ratio uncertainties for the wideband CT calibration system are 10 ppm ($k=2$) up to 10 kHz and less than 120 ppm from 10 kHz to 150 kHz; these uncertainties do not include the uncertainty of the reference CT. Additionally, the operational conditions and setup design choices, such as instrument warm-up duration, grounding methods, measurement shunt selection, and cable type, were evaluated for their impact on measurement uncertainty and repeatability. The results highlight the significance of minimizing parasitic impedances at higher frequencies and maintaining consistent testing conditions. The developed calibration setup provides a robust foundation for future standardization efforts and practical guidance to characterize CT performance in the increasingly important supraharmonic frequency range. Full article

To enhance the overall operational efficiency of heavy haul railway port stations, which serve as critical hubs in rail–water intermodal transportation systems, this study develops a novel scheduling optimization method that integrates operation plans and resource allocation. By analyzing the operational processes of heavy haul trains and shunting operation modes within a hybrid unloading system, we establish an integrated scheduling optimization model. To solve the model efficiently, a dual-agent advantage actor–critic with Pareto reward shaping (DAA2C-PRS) algorithm framework is proposed, which captures the matching relationship between operations and resources through joint actions taken by the train agent and the shunting agent to depict the scheduling decision process. Convolutional neural networks (CNNs) are employed to extract features from a multi-channel matrix containing real-time scheduling data. Considering the objective function and resource allocation with capacity, we design knowledge-based composite dispatching rules. Regarding the communication among agents, a shared experience replay buffer and Pareto reward shaping mechanism are implemented to enhance the level of strategic collaboration and learning efficiency. Based on this algorithm framework, we conduct experimental verification at H port station, and the results demonstrate that the proposed algorithm exhibits a superior solution quality and convergence performance compared with other methods for all tested instances. Full article

Background: The COVID-19 pandemic disrupted healthcare systems globally, raising concerns about its negative impact on patients with chronic liver diseases by contributing to hepatic decompensations such as acute variceal bleeding (AVB). This study aimed to evaluate the impact of the COVID-19 pandemic on clinical outcomes in cirrhotic patients with AVB in Germany. Methods: This retrospective national multicenter study compared patients with cirrhosis and AVB treated at four tertiary care centers in Germany before (2016–2020) and during the pandemic (2020–2022). The primary endpoint was 6-week mortality, and secondary outcomes included infections, transfusion requirement and rebleeding. Results: The baseline characteristics of the 247 patients were largely comparable between the two groups, however metabolic dysfunction-associated steatotic liver disease was more prevalent during the pandemic compared to the pre-pandemic period (12.5% vs. 4.8%, p = 0.048). Only one patient tested positive for SARS-CoV-2. Six-week mortality (32.2% vs. 30.1%; p = 0.767) and rebleeding rates (22.8% vs. 22.3%; p = 1.000) did not differ significantly between groups. Interestingly, intubation rates, length of stay on the intensive care unit, post AVB infection rates and types of infection were also comparable (all p > 0.05), while transjugular intrahepatic portosystemic shunt placement (TIPS) after bleeding was performed more frequently during the pandemic (23.2% vs. 11.3%, p = 0.019). Conclusions: Relevant patient-related AVB outcomes were unaffected during the COVID-19 pandemic. These findings suggest the resilience of critical AVB management practices in German tertiary centers. The increased use of TIPS and MASLD prevalence during the pandemic may reflect evolving clinical practice and patient profiles warranting further investigation. Full article

Hyperammonaemia in dogs is most frequently associated with hepatic encephalopathy caused by portosystemic shunting. This retrospective multicentre study aimed to investigate the prevalence of hyperammonaemia and hepatic encephalopathy in dogs with recent or ongoing epileptic seizures. Furthermore, we sought to evaluate if transient post-ictal hyperammonaemia as a sequela to seizure activity occurs, as reported in humans and recently in cats. The medical records of all dogs presented between 2014 and 2024 to ten AniCura Veterinary Hospitals in Sweden were retrospectively reviewed to obtain those with recent or ongoing epileptic seizures with concurrent analysis of ammonia. The records of 267 dogs were extracted for further review. Inclusion criteria included information regarding the description and characterisation of the seizures and the analysis of ammonia within 24 h after last reported seizure activity. Additionally, hepatic function tests were required in dogs with elevated ammonia. In total, 58 dogs fulfilled the inclusion criteria, and 10 of those dogs (17%) had hyperammonaemia. Three dogs had documented hepatopathy, and two of them had surgically corrected portosystemic shunts. In seven dogs, no definitive cause of hyperammonaemia could be established. Three of the seven dogs had no evidence of portosystemic shunts, and six had no laboratory evidence supporting acute liver failure. According to the findings in this retrospective study, hyperammonaemia in the absence of evident acute hepatic failure or portosystemic shunting can occur in dogs with epileptic seizures, indicating that other differentials than hepatic encephalopathy should be considered. This study could not confirm the hypothesis of hyperammonaemia being a transient consequence of seizures. Full article

This paper presents a novel methodology for the optimal sizing of solar photovoltaic (PV) systems in distribution networks by determining the monthly optimum tilt and azimuth angles to maximize solar energy capture. Using one year of solar irradiation data, the Grey Wolf Optimizer (GWO) is employed to optimize the tilt and azimuth angles with the objective of maximizing monthly solar insolation. Unlike existing approaches that assume fixed azimuth angles, the proposed method calculates both tilt and azimuth angles for each month, allowing for a more precise alignment with solar trajectories. The optimized orientation parameters are subsequently utilized to determine the optimal number and placement of PV panels, as well as the optimal location and sizing of shunt capacitor (SC) banks, for the IEEE 69-bus distribution system. This optimization is performed under peak load conditions using the GWO, with the objectives of minimizing active power losses, enhancing voltage profile stability, and maximizing PV system penetration. The long-term impact of this approach is assessed through a 20-year energy and economic savings analysis, demonstrating substantial improvements in energy efficiency and cost-effectiveness. Full article

The performance and beam quality of the new fourth-generation synchrotron light source with ultra-low emittance are highly susceptible to coupled-bunch instabilities. These instabilities arise from the interaction between the bunched electron beam and the surrounding vacuum chamber installations. To mitigate these effects, the installation of a transverse bunch-by-bunch feedback system is planned. This system will comprise a button-type beam position monitor (BPM) for beam signal detection, a digital feedback controller, a broadband power amplifier, and a broadband stripline kicker as the primary actuator. One of the critical challenges lies in the development of the stripline kicker, which must be optimized for high shunt impedance and wide bandwidth while minimizing beam-coupling impedance. This work focuses on the comprehensive design of the stripline kicker intended for transverse (horizontal and vertical) bunch-by-bunch feedback in the Siam Photon Source II (SPS-II) storage ring. The stripline kicker design also incorporates features to enable its use for beam excitation in the SPS-II tune measurement system. The optimization process involves analytical approximations and detailed numerical electromagnetic field analysis of the stripline’s 3D geometry, focusing on impedance matching, field homogeneity, power transmission, and beam-coupling impedance. The details of engineering design are discussed to ensure that it meets the fabrication possibilities and stringent requirements of the SPS-II accelerator. Full article

Accurate boundary detection is critical for autonomous trackless rubber-wheeled vehicles in underground coal mines, as it prevents lateral collisions with tunnel walls. Unlike open-road environments, underground tunnels suffer from poor illumination, water mist, and dust, which degrade visual imaging. To address these challenges, this paper proposes a navigable area computation for underground autonomous vehicles via ground feature and boundary processing, consisting of three core steps. First, a real-time point cloud correction process via pre-correction and dynamic update aligns ground point clouds with the LiDAR coordinate system to ensure parallelism. Second, corrected point clouds are projected onto a 2D grid map using a grid-based method, effectively mitigating the impact of ground unevenness on boundary extraction; third, an adaptive boundary completion method is designed to resolve boundary discontinuities in junctions and shunting chambers. Additionally, the method emphasizes continuous extraction of boundaries over extended periods by integrating temporal context, ensuring the continuity of boundary detection during vehicle operation. Experiments on real underground vehicle data validate that the method achieves accurate detection and consistent tracking of dual-sided boundaries across straight tunnels, curves, intersections, and shunting chambers, meeting the requirements of underground autonomous driving. This work provides a rule-based, real-time solution feasible under limited computing power, offering critical safety redundancy when deep learning methods fail in harsh underground environments. Full article

This review delves into the complexities of managing portal vein thrombosis (PVT) in the context of liver transplantation (LT). PVT, which is a common finding in cirrhotic livers, can significantly jeopardize LT outcomes. Here, we explore the incidence, underlying mechanisms, and comprehensive management strategies for PVT throughout the pre-, intra-, and postoperative phases of LT in cirrhotic patients. Before transplantation, key interventions include anticoagulation therapies, transjugular intrahepatic portosystemic shunts (TIPS), and various endovascular techniques aimed at recanalizing the portal vein. During LT, surgical approaches range from straightforward eversion thrombectomy to more intricate procedures, such as jump grafts from the superior mesenteric vein (SMV), renoportal anastomosis (RPA), and portocaval hemitransposition, tailored to the extent of the thrombosis. In cases of extensive PVT, multivisceral transplantation (MVT) emerges as a viable option. Post-transplant management centers on thromboprophylaxis and anticoagulation, balancing the prevention of thrombotic events with the risk of bleeding complications. This review underscores the critical importance of early identification and proactive management of PVT to enhance outcomes for LT candidates. Full article

In this work, we investigate the electrical properties of a metal–insulator–semiconductor (MIS) heterojunction based on porous silicon dioxide (Ag/pSiO₂/Si). The porous silicon (PS) films were elaborated by electrochemical anodization under specific experimental conditions to obtain a porosity of about 55%. Porous silicon (PS) was oxidized by IR-RTP at different oxidation temperatures (Tox) ranging from 200 to 950 °C under an oxygen atmosphere. The morphology of the samples was analyzed using a scanning electron microscope (SEM). Ag/Al and Ag contacts were screen printed on the back and front sides of the heterojunction, respectively. Both the series and shunt resistances were derived from dark current–voltage (I–V) characteristics related to the various Ag/pSiO₂/Si heterojunctions. In this context, the reflectance was also measured at different oxidation temperatures to investigate its correlation with the series resistance (Rs) and shunt resistance (Rsh). The optimum electrical performance was obtained for an oxidation temperature close to 400 °C. Depending on the pSiO₂ thickness, two conduction mechanisms were highlighted within the devices. For a Tox below 200 °C, as well as for the non-oxidized devices, the conduction mechanism is governed by the tunneling current through the pSiO₂ film. However, when the Tox increases and exceeds 200 °C, the pSiO₂ thickness increases, leading to the switching of the conduction mechanism to a thermionic instead of a tunneling effect mechanism. Full article

Background: The perfusion of viscera, kidney, and spinal cord represents one of the main concerns during open repair (OR) of Thoraco-Abdominal Aortic Aneurisms (TAAAs). Passive shunting (PS) has been historically used for intraoperative distal aortic perfusion but has been progressively replaced almost entirely by partial left-sided heart or total cardiopulmonary bypass with extra-corporeal circulation (ECC). Despite several advantages of these methods, PS still has potential in mitigating some drawbacks of long extracorporeal circuits connected with centrifugal or roller pumps, such as the need for cardiac and great vessels cannulation, priming and large intravascular fluid volume shifts, high heparin dose, immunosuppressive effects, and systemic inflammatory response syndrome. Methods: This study prospectively analyzed data of a cohort of patients who underwent TAAA OR using a PS in a single institution. Outcomes of interest were mortality, rate of mesenteric, renal and spinal cord ischemia, cardiac complications, and intraoperative hemodynamic stability achieved in this setting. Our institutional bundle and a comprehensive literature review about the different configurations and applicability of PS for TAAA OR is also reported. The search was performed based on three databases (PubMed, EMBASE, and Cochrane Library) by two independent reviewers (LS and AA) from inception to 31 December 2023, and the reported clinical results (visceral, renal, and spinal cord complications and mortality) using PS during TAAAs OR were analyzed. Results: Between March 2021 and December 2023, 51 TAAA repairs were performed and eleven patients (n = 8, 73% male; mean age 67 years, range 63–79) were operated using a PS for a total of one (9%) type I, one (9%) type II, two (18%) type III, five (45%) type IV, and two (18%) type V TAAA. In our early experience, PS was indicated for limited staff resources during the COVID-19 pandemic to treat five non-deferable cases. The sixth and seventh patients were selected for PS as they already had a functioning axillo-bifemoral bypass that was used for this purpose. For the most recent cases, PS was chosen as the primary perfusion method according to a score based on clinical and anatomical factors with ECC as a bailout strategy. Selective renal perfusion with cold (4 °C) Custodiol solution was the method of choice for renal protection in all cases while antegrade perfusion of the coeliac trunk and the superior mesenteric artery was assured by PS through a loop graft (8–10mm) proximally anastomosed to the axillary artery (10 patients, 90.9%) or the descending thoracic aorta (one patient, 9%) and distally anastomosed to the infrarenal aorta (3), common iliac (3), or femoral vessels (5). In-hospital mortality was 9% as one patient died on the 10th postoperative day from mesenteric ischemia following hemodynamic instability; permanent spinal cord ischemia rate was 0% and the rate of AKI stage 3 was 9% (one patient). Bailout shifting to ECC was never required. No cardiac complications, nor a significant increase in serum CK-MB were reported in any patient. No prolonged severe intraoperative hypotension episodes (Mean Arterial Pressure < 50 mmHg) were assessed using the Software Acumen Analytics (Edwards LifeSciences, Irvine CA, USA). No peri-operative coagulopathy nor major bleeding was reported. Conclusions: Our experience showed satisfactory outcomes with the use of PS in specifically selected cases. Current data indicate that PS may represent an alternative to ECC techniques during TAAAs OR in high volume centers where assisted extracorporeal circulation could eventually be applied as a bailout strategy. However, due to the small sample size of this and previously published series, more data are needed to clearly define the potential role of such approach during TAAA OR. Full article

Background/Objectives: This work aims to clarify whether the subtenon use of the sodium hyaluronate product Healaflow in filtrating surgery with PreserFlo MicroShunt positively influences the early postoperative course in terms of control of intraocular pressure, hypotony, and needling rate. Methods: A retrospective, randomized controlled, interventional, single-center trial was performed at the Ludwig Maximilians-University Munich from January 2024 to July 2024. Only patients with primary open angle glaucoma (POAG) were included. In all patients, a complete ophthalmological examination including best corrected visual acuity (BCVA), automated refraction, and Goldman tonometry was performed at 2 days, 1–4 and 5–8 weeks, and 3–4 and 5–6 months after surgery. Healaflow was injected underneath the tenon during filtrating surgery with PreserFlo MicroShunt in addition to mitomycin C (MMC). The Healaflow group was compared to a control group with POAG patients in which Healaflow was not used during surgery with PreserFlo MicroShunt and MMC. Results: A total of 45 eyes of 45 patients were included, with 20 eyes in the Healaflow group and 25 eyes in the control group. In both groups, a significant reduction in IOP and medication could be observed: complete surgical success (IOP ≥ 6 mm Hg and ≤17 mm Hg, without surgical complications or complete loss of vision) was reached in 88% of patients in the Healaflow group at the last follow-up. In 95% of patients in the control group, complete success could be observed. The success rates did not significantly differ between the two groups (p = 0.568). Hypotony rates were 35% in the Healaflow and 12% in the control group after two days (p = 0.083); the rates equalized after 1–4 weeks (p = 1). Needling rates were comparable between both groups (25% versus 20%, p = 0.731). Conclusions: PreserFlo MicroShunt implantation with MMC was equally effective in terms of reduction in IOP and medication in both scenarios with additional or without the use of Healaflow. Postoperative hypotony and needling rates did not significantly differ between the two groups. The additional effects of Healaflow on anti-scarring and maintaining space are likely too minimal to cause significant differences in IOP or medication when already treated with MMC. Full article

Background: High concentrations of supplemental oxygen (FiO₂ > 0.6) are commonly used to treat acute hypoxemia in critically ill patients. However, the effects of High FiO₂ in patients with COVID-19 remain unclear, particularly regarding its impact on hypoxic pulmonary vasoconstriction (HPV) and ventilation–perfusion (V/Q) mismatch. Objective: This study aims to evaluate whether administering lower concentrations of inspired oxygen (FiO₂ < 0.6) is associated with improved outcomes—namely reduced need for mechanical ventilation and mortality—in patients with COVID-19 and severe pulmonary involvement. Methods: This retrospective observational cohort included 201 patients with confirmed COVID-19. Patients were grouped by mean FiO₂ during the first 24–48 h: High FiO₂ (≥0.60) or Low FiO₂ (<0.60). The primary outcome was the requirement for mechanical ventilation; the secondary outcome was in-hospital mortality. A composite endpoint (mechanical ventilation and in-hospital death) was also evaluated. Analyses included logistic regression and Kaplan–Meier survival with log-rank testing. Results: High FiO₂ (≥0.60) was associated with higher odds of the composite outcome (mechanical ventilation and in-hospital death). In multivariable analysis, Low FiO₂ remained associated with lower odds (adjusted OR 0.18; 95% CI 0.08–0.39; p < 0.001). Unadjusted rates were 43.1% vs. 16.1% for mechanical ventilation and 34.3% vs. 8.1% for in-hospital death (High vs. Low FiO₂; both p < 0.001). Event-free survival favored the Low FiO₂ group (log-rank p < 0.001). The model showed excellent discrimination (AUC 0.96; 95% CI 0.92–0.99). Conclusions: Higher early FiO₂ exposure was associated with worse clinical outcomes in severe COVID-19. These findings are consistent with physiological models in which excess oxygen may attenuate hypoxic pulmonary vasoconstriction and increase shunt/dead space. Prospective studies are warranted to assess causality and refine oxygen targets. Full article

To address the demands for wide-range and high-precision current measurement, this paper proposes a novel current sensor design that integrates spin sensing technology, magnetic shunt effect, and a multi-sensor data fusion algorithm. The spin valve sensors accurately detect the magnetic field generated by the signal current, while the soft magnetic shunt structure attenuates the magnetic field to a level suitable for the spin valve sensors. Consequently, the detection current range can be extended by 6.8 times. Using four spin valve sensors and data fusion with an averaging algorithm, the system can calibrate the errors caused by the displacement or tilt of the current-carrying wire. Experimental results demonstrate that the current sensor achieves a sensitivity of 61.6 mV/V/A, an excellent linearity of 0.55%, and robust measurement performance, as well as strong anti-interference capability. Our study offers a novel solution for high-precision, wide-range current measurement in applications such as those in new energy vehicle electronics and precision electric energy metering. Full article

Adaptive Linear Neuron (ADALINE) is a well-known neural network method that has been utilized for generating a reference current intended to regulate the operation of shunt-typed active harmonic filters (SAHFs). These filters are essential for improving power quality by mitigating harmonic disturbances and restoring current waveform symmetry in power systems. While the latest variant, Simplified ADALINE, offers notable advantages over its predecessors, such as a reduced complexity and faster learning speed, its performance has primarily been evaluated under stable grid conditions, leaving its performance under distorted environments largely unexplored. To address this gap, this work introduces two key modifications to the Simplified ADALINE framework: (1) the integration of a new phase-tracking algorithm based on the concept of orthogonality and selective filtering, and (2) transitioning from the direct current control (DCC) to an indirect current control (ICC) mechanism. Test environments featuring distorted grids and nonlinear rectifier loads are simulated in MATLAB/Simulink software to evaluate the performance of the proposed method against the existing Simplified ADALINE method. The key findings demonstrate that the proposed method effectively handled harmonic distortion and noise disturbance. As a result, the associated SAHF achieved an additional reduction in %THD (by 10.77–13.78%), a decrease in reactive power (by 58.3 VAR–67 VAR), and improved grid synchronization with a smaller phase shift (by 0.9–1.2°), while also maintaining proper waveform symmetry even in challenging grid conditions. Full article