Search Results (30)

This work introduces a wine glass-shaped planar ultra-wideband (UWB) antenna. The antenna achieves a compact form factor by reducing lateral width through Bézier curve shaping and a trident feed, while maintaining length for low-frequency operation. The wine-glass-shaped radiator increases shunt capacitance and enhances midband impedance matching, as demonstrated by equivalent circuit analysis, while the trident feed improves matching at higher frequencies. This design yields a 92% fractional bandwidth (3.2–8.7 GHz) within a compact volume of $0.37{\lambda }_0\times 0.13{\lambda }_0\times 0.0013{\lambda }_0$. The prototype is fabricated on two 50-μm-thick polyimide flexible copper-clad laminates (FCCL), and its performance is evaluated in an anechoic chamber. The measured results demonstrate omnidirectional radiation with an efficiency of over 80% across the UWB band. With broad operational range and compactness, the antenna is well-suited for IoT and wearable sensing applications. Full article

Background/Objectives: Studies have indicated that forgoing lung shunt fraction measurement in select patients undergoing Yttrium 90 (Y90) transarterial radioembolization (TARE) may be safe without sacrificing efficacy. This study evaluated the safety and efficacy of a streamlined treatment in patients with small hepatocellular carcinoma (HCC) receiving resin-based TARE. Methods: Patients who received single-session Y90 TARE between September 2023 and May 2024 were retrospectively evaluated. Treatment response was evaluated at the 3-month follow-up using the modified Response Evaluation Criteria in Solid Tumors (mRECIST) criteria. Adverse events (AEs) ≥ Grade 3 were recorded post-procedurally at 3 months. The time from the interventional radiology clinic visit to the procedure date was compared to patients receiving the conventional TARE treatment. Results: Ten consecutive patients were treated with 12 treatments. Each treatment targeted an isolated lesion with median size of 2.5 cm (IQR: 2.1, 2.9). Two patients received two treatments (one for treatment of a separate lesion and the other for the initial incomplete targeting of the tumor). The median delivered tumor dose was 377.7 Gy (IQR: 246.5, 570.1). No patients developed ≥ Grade 3 AEs post-TARE. Complete response was achieved in 11/12 patients (92%). The conventional cohort consisted of 60 patients, all OPTN T2 treated with radiation segmentectomy with glass microspheres. Patients undergoing SSMT had a median time from clinic visit to treatment of 26.5 days (IQR: 15.3, 39) vs. 61 days (IQR: 48, 88.8) in the conventional TARE group (p < 0.001). Conclusions: Streamlined single-session resin-based Y90-TARE in patients with OPTN T2 stage HCC is feasible, efficacious, safe, and associated with reduced time to treatment. Full article

Background and Clinical Significance: Pulmonary hypertension (PH) is characterized by an increase in mean pulmonary arterial pressure and pulmonary vascular resistance. It is frequently encountered in patients with significant intracardiac shunts, often necessitating the implementation of a closure device or surgical correction. Nevertheless, the occurrence of a concomitant atrial septal defect (ASD) with a right-to-left shunt inducing left ventricular dysfunction is a rare phenomenon. Case Presentation: A 69-year-old female patient with a history of heart failure (with preserved ejection fraction) and end-stage renal disease on hemodialysis presented to an outside facility, with syncope and hypoxia. She was recently diagnosed with severe pulmonary hypertension (measuring 86 mmHg). Right heart catheterization (RHC) revealed precapillary pulmonary hypertension (88/37/54 mmHg), prompting the initiation of intravenous epoprostenol. Nevertheless, the patient was persistently hypoxic, raising the possibility of a concomitant diagnosis. Upon review of the prior echocardiogram, which included a bubble study, an intracardiac shunt was identified. It was hypothesized that a combination of right ventricular failure and the right-to-left shunt resulting from the ASD contributed to the persistent hypoxemia. In light of this, prostacyclin therapy was continued alongside adjunctive vasopressors, resulting in clinical stabilization. The patient was eventually discharged with a treatment regimen that included subcutaneous Treprostinil. Conclusions: It is important to recognize that the consequences of PH are extensive, and that a rare yet significant etiology for persistent hypoxemia may be attributed to right-to-left shunting. Full article

Aims. To identify the difference between adult patients with septal defects and paroxysmal atrial fibrillation (AF) and patients without a history of arrhythmia using the left atrial (LA) volume and function parameters, to reveal the parameters associated with AF development. Methods and results. In this prospective study, 81 patients with septal defects and left-to-right shunts were enrolled between 2021 and 2023 and divided into two groups: with paroxysmal AF and without AF. Left atrial function was analyzed based on the indexed left atrial volumes (LAVI and preA-LAVI), ejection fraction (LAEF), expansion index (LAEI), reservoir (LAS-r), conduit (LAS-cd) and contractile (LAS-ct) strain, and stiffness index (LASI) using a Philips CVx3D ultrasound system (Philips, Amsterdam, The Netherlands) and corresponding software. In total, 26 patients with paroxysmal atrial fibrillation (mean age: 59.6 ± 11.7 years, female: 80.8%) and 55 patients with septal defects without any history of arrhythmias (mean age: 44.8 ± 11.6 years, female: 81.8%) were included. All patients were in the NYHA class I or II at baseline. Our findings demonstrated a significant difference between all LA function parameters in the two groups. Upon univariable analysis, the LAVI, preA-LAVI, LASI, LAEF, LAEI, LAS-r, LAS-c, LAS-ct, age, cardiac index, E/A, and RV pressure were found to be associated with AF. The multivariate analysis identified LAVI (OR 1.236, 95% CI 1.022–1.494, p = 0.03), LAS-r (OR 0.723, 95% CI 0.556–0.940, p = 0.02), and LAS-ct (OR 1.518, 95% CI 1.225–1.880, p < 0.001) as independent predictors of AF development. The proposed model demonstrated high sensitivity and specificity with an adjusted classification threshold of 0.38 (AUC: 0.97, 95% CI 0.93–1.00, sensitivity 92% and specificity 92%, p < 0.001). Conclusions. The assessment of LA function using speckle-tracking echocardiography demonstrated significantly different values in the AF group among patients with congenital septal defects. This technique can therefore be implemented in routine clinical management. The key message. Atrial fibrillation development in adult patients with congenital septal defects and a left-to-right shunt is associated with the changes in left atrial function under conditions of an increased preload. Full article

Background/Objectives: Obstructive hydrocephalus associated with vestibular schwannoma (VS) is the most common in giant VS. Despite tumor removal, some patients may require ongoing ventriculo-peritoneal (VP) surgery. This investigation explores the factors contributing to the requirement for VP surgery following VS surgery in instances of persistent hydrocephalus (HCP). Methods: Volumetric MRI analyses of pre- and postoperative tumor volumes, cerebellum, cerebrum, ventricle system, fourth ventricle, brainstem, and peritumoral edema were conducted using Brainlab Smartbrush and 3D Slicer. The total brain volume was defined as the sum of the cerebrum, cerebellum, and brainstem. ROC analyses were performed to identify the optimum cut-off values of the volumetric data. Results: Permanent cerebrospinal fluid (CSF) diversion after surgery was indicated in 12 patients (12/71; 16.9%). The ratio of baseline volume fraction of brain ventricles to total brain ventricle volume (VTB ratio) was found to predict postoperative VP shunt dependency. The AUC was 0.71 (95% CI: 0.51–0.91), and the optimum threshold value (</≥0.449) yielded a sensitivity and specificity of 67% and 81%, respectively. Multivariable logistic regression analyses of imaging data (pre- and postoperative VS volume, VTB ratio, and extent of resection (%) (EoR)) and patient-specific factors revealed that an increased VTB ratio (≥0.049, OR: 6.2, 95% CI: 1.0–38.0, p = 0.047) and an EoR < 96.4% (OR: 9.1, 95% CI: 1.2–69.3, p = 0.032) were independently associated with postoperative VP shunt dependency. Conclusions: Primary tumor removal remains the best treatment to reduce the risk of postoperative persistent hydrocephalus. However, patients with an increased preoperative VTB ratio are prone to needing postoperative VP shunt surgery and may benefit from perioperative EVD placement. Full article

In neonates with acute lung injury (ALI), targeting lower oxygenation saturations is suggested to limit oxygen toxicity while maintaining vital organ function. Although thresholds for cerebral autoregulation are studied for the management of premature infants, the impact of hypoxia on hemodynamics, tissue oxygen consumption and extraction is not well understood in term infants with ALI. We examined hemodynamics, cerebral autoregulation and fractional oxygen extraction, as measured by near-infrared spectroscopy (NIRS) and blood gases, in a neonatal porcine oleic acid injury model of moderate ALI. We hypothesized that in ALI animals, cerebral oxygen extraction would be increased to a greater degree than kidney or gut oxygen extraction as indicative of the brain’s adaptive efforts to increase cerebral oxygen extraction at the expense of splanchnic end organs. Fifteen anesthetized, ventilated 5-day-old neonatal piglets were divided into moderate lung injury by treatment with oleic acid or control (sham injection). The degree of lung injury was quantified at baseline and after establishment of ALI by blood gases, ventilation parameters and calculated oxygenation deficit, hemodynamic indices by echocardiography and lung injury score by ultrasound. PaCO₂ was maintained constant during ventilation. Cerebral, renal and gut oxygenation was determined by NIRS during stepwise decreases in inspired oxygen from 50% to 21%, correlated with PaO₂ and PvO₂; changes in fractional oxygen extraction (ΔFOE) were calculated from NIRS and from regional blood gas samples. The proportion of cerebral autoregulation impairment attributable to blood pressure, and to hypoxemia, was calculated from autoregulation nomograms. ALI manifested as hypoxemia with increasing intrapulmonary shunt fraction, decreased lung compliance and increased resistance, and marked increase in lung ultrasound score. Brain, gut and renal NIRS, obtained from probes placed over the anterior skull, central abdomen and flank, respectively, correlated with concurrent SVC (brain) or IVC (gut, renal) PvO₂ and SvO₂. Cerebral autoregulation was impaired after ALI as a function of blood pressure at all FiO₂ steps, but predominantly by hypoxemia at FiO₂ < 40%. Cerebral ΔFOE was higher in ALI animals at all FiO₂ steps. We conclude that in an animal model of neonatal ALI, cerebrovascular blood flow regulation is primarily dependent on oxygenation. There is not a defined oxygenation threshold below which cerebral autoregulation is impaired in ALI. Cerebral oxygen extraction is enhanced in ALI, reflecting compensation for exhausted cerebral autoregulation due to the degree of hypoxemia and/or hypotension, thereby protecting against tissue hypoxia. Full article

(1) Background: In ⁹⁰Y-TARE treatments, lung-absorbed doses should be calculated according to the manufacturer’s instructions, using the MIRD-scheme. This scheme is derived from the assumption that ⁹⁰Y-microspheres deliver the dose in a water-equivalent medium. Since the density of the lungs is quite different from that of the liver, the absorbed dose to the lungs could vary considerably, especially at the liver/lungs interface. The aim of this work is to compare the dosimetric results obtained by two dedicated software packages implementing a water-equivalent dose calculation and a Monte Carlo (MC) simulation, respectively. (2) Methods: An anthropomorphic IEC phantom and a retrospective selection of 24 patients with a diagnosis of HCC were taken into account. In the phantom study, starting from a ⁹⁰Y-PET/CT acquisition, the liver cavity was manually fixed with a uniform activity concentration on PET series, while the lung compartment was manually expanded on a CT series to simulate a realistic situation in which the liver and lungs are adjacent. These steps were performed by using MIM ⁹⁰Y SurePlan. Then, a first simulation was carried out with only the liver cavity filled, while a second one was carried out, in which the lung compartment was also manually fixed with a uniform activity concentration corresponding to 10% lung shunt fraction. MIM ⁹⁰Y SurePlan was used to obtain Voxel S-Value (VSV) approach dose values; instead, Torch was used to obtain MC approach dose values for both the phantom and the patients. (3) Results: In the phantom study, the percentage mean dose differences (∆D%) between VSV and MC in the first and second simulation, respectively were found to be 1.2 and 0.5% (absolute dose variation, ∆D, of 0.7 and 0.3 Gy) for the liver, −56 and 70% (∆D of −0.3 and −16.2 Gy) for the lungs, and −48 and −60% (∆D of −4.3 and −16.5 Gy) for the Liver/Lungs Edge region. The patient study reports similar results with ∆D% between VSV and MC of 7.0%, 4.1% and 6.7% for the whole liver, healthy liver, and tumor, respectively, while the result was −61.2% for the left lung and −61.1% for both the right lung and lungs. (4) Conclusion: Both VSV and MC allowed accurate radiation dose estimation with small differences (<7%) in regions of uniform water-equivalent density (i.e., within the liver). Larger differences between the two methods (>50%) were observed for air-equivalent regions in the phantom simulation and the patient study. Full article

Background: Pulmonary endarterectomy (PEA) is the treatment of choice for patients with chronic thromboembolic pulmonary hypertension (CTEPH) with accessible lesions. Breathing pure oxygen (hyperoxia) during right heart catheterization (RHC) allows for the calculation of the right-to-left shunt fraction (Qs/Qt). In the absence of intracardiac shunt, Qs/Qt can be used as a marker of ventilation–perfusion mismatch in patients with CTEPH. This study involved investigating Qs/Qt after PEA and its relation to other disease-specific outcomes. Study design and Methods: This study is a retrospective study that focuses on patients with operable CTEPH who had Qs/Qt assessment during RHC before and 1 year after PEA. Additionally, 6 min walking distance (6MWD), WHO functional class (WHO-FC), and NT-proBNP were assessed to calculate a four-strata risk score. Results: Overall, 16 patients (6 females) with a median age of 66 years (quartiles 55; 74) were included. After PEA, an improvement in mean pulmonary artery pressure (38 [32; 41] to 24 [18; 28] mmHg), pulmonary vascular resistance (5.7 [4.0; 6.8] to 2.5 [1.4; 3.8] WU), oxygen saturation (92 [88; 93]% to 94 [93; 95]%), WHO-FC, and risk score was observed (all p < 0.05). No improvement in median Qs/Qt could be detected (13.7 [10.0; 17.5]% to 13.0 [11.2; 15.6]%, p = 0.679). A total of 7 patients with improved Qs/Qt had a significant reduction in risk score compared to those without improved Qs/Qt. Conclusion: PEA did not alter Qs/Qt assessed after 1 year in operable CTEPH despite an improvement in hemodynamics and risk score, potentially indicating a persistent microvasculopathy. In patients whose shunt fraction improved with PEA, the reduced shunt was associated with an improvement in risk score. Full article

A new controller based on a fractional-order synergetic controller (FOSC) is proposed for a three-level T-type inverter using a shunt active power filter (SAPF). The SAPF is designed to compensate for the reactive power and eliminate the current harmonics caused by non-linear loads, in cases of distorted or unbalanced source voltages. The proposed FOSC technique with the designed parameters and defined macro-variable is a robust control technique that operates well in both transient and steady-state scenarios, ensuring fast convergence and closed-loop system stability. The FOSC technique utilizes a phase-locked loop (PLL) technique on a self-tuning filter (STF) to enhance the SAPF’s ability to compensate current harmonics and reactive power in all situations involving non-linear loads and source voltage variations according to IEEE Std. 519. The proposed control was implemented and verified using Matlab software, where the obtained results were compared with the results of the conventional control based on proportional-integral (PI) controllers in different operating conditions. The results indicate that the proposed FOSC technique outperformed the traditional control in terms of DC voltage tracking and the minimization of the total harmonic distortion of the current. Full article

In this paper, a switchable filter based on the microstrip line (ML) with reflectionless-bandpass-to-reflectionless-bandstop responses is designed, theoretically validated, and fabricated. This single-port reflectionless bandpass filter (R-BPF) consists of a BPF and a shunt-connected bandstop section with terminated absorption resistors. The single-port reflectionless bandstop filter (R-BSF) is made of a BSF and a parallel bandpass circuit with terminated absorption resistors. These two reflectionless operational modes, namely R-BPF and R-BSF, are allowed to reconfigure the multifunctional filtering device using PIN diodes. In addition, a theoretical analysis of terminal impedance is performed to illustrate the working mechanism of the reflectionless response. To demonstrate the application of the proposed designs, a prototype of the switchable filter for R-BPF to R-BSF responses is fabricated and measured. For the R-BPF mode, the 3-dB fractional bandwidth (FBW) is 36.75% (1.67–2.42 GHz) with a 10-dB reflectionless bandwidth (RBW) of 1.36–2.58 GHz (i.e., FBW of 61.9%). For the R-BSF mode, the 10-dB bandwidth is 13% (1.85–2.11 GHz) with a 10.7-dB RBW of 1–3 GHz (i.e., FBW of 100%). An acceptable agreement between the measured and simulated results has been achieved. Full article

Background: Limited data are available for the oxygenation changes following prone position in relation to hemodynamic and pulmonary vascular variations in acute respiratory distress syndrome (ARDS), using reliable invasive methods. We aimed to assess oxygenation and hemodynamic changes between the supine and prone posture in patients with ARDS and identify parameters associated with oxygenation improvement. Methods: Eighteen patients with ARDS under protective ventilation were assessed using advanced pulmonary artery catheter monitoring. Physiologic parameters were recorded at baseline supine position, 1 h and 18 h following prone position. Results: The change in the Oxygenation Index (ΔOI) between supine and 18 h prone significantly correlated to the concurrent change in shunt fraction (r = 0.75, p = 0.0001), to the ΔOI between supine and 1 h prone (r = 0.73, p = 0.001), to the supine acute lung injury score and the OI (r = −0.73, p = 0.009 and r = 0.69, p = 0.002, respectively). Cardiac output did not change between supine and prone posture. Moreover, there was no change in pulmonary pressure, pulmonary vascular resistances, right ventricular (RV) volumes and the RV ejection fraction. Conclusions: The present investigation provides physiologic clinical data supporting that oxygenation improvement following prone position in ARDS is driven by the shunt fraction reduction and not by changes in hemodynamics. Moreover, oxygenation improvement was not correlated with RV or pulmonary circulation changes. Full article

In this paper, in an in situ prepared three-terminal Josephson junction based on the topological insulator Bi${}_4$Te${}_3$ and the superconductor Nb the transport properties are studied. The differential resistance maps as a function of two bias currents reveal extended areas of Josephson supercurrent, including coupling effects between adjacent superconducting electrodes. The observed dynamics for the coupling of the junctions is interpreted using a numerical simulation of a similar geometry based on a resistively and capacitively shunted Josephson junction model. The temperature dependency indicates that the device behaves similar to prior experiments with single Josephson junctions comprising topological insulators’ weak links. Irradiating radio frequencies to the junction, we find a spectrum of integer Shapiro steps and an additional fractional step, which is interpreted with a skewed current–phase relationship. In a perpendicular magnetic field, we observe Fraunhofer-like interference patterns in the switching currents. Full article

There is no noninvasive method to estimate lung shunting fraction (LSF) in patients with liver tumors undergoing Yttrium-90 (Y90) therapy. We propose to predict LSF from noninvasive dynamic contrast enhanced (DCE) MRI using perfusion quantification. Two perfusion quantification methods were used to process DCE MRI in 25 liver tumor patients: Kety’s tracer kinetic modeling with a delay-fitted global arterial input function (AIF) and quantitative transport mapping (QTM) based on the inversion of transport equation using spatial deconvolution without AIF. LSF was measured on SPECT following Tc-99m macroaggregated albumin (MAA) administration via hepatic arterial catheter. The patient cohort was partitioned into a low-risk group (LSF $\le$ $10\%$) and a high-risk group (LSF $>$ $10\%$). Results: In this patient cohort, LSF was positively correlated with QTM velocity $\left|\mathit{u}\right|$ (r = 0.61, F = 14.0363, p = 0.0021), and no significant correlation was observed with Kety’s parameters, tumor volume, patient age and gender. Between the low LSF and high LSF groups, there was a significant difference for QTM $\left|\mathit{u}\right|$ (0.0760 ± 0.0440 vs. 0.1822 ± 0.1225 mm/s, p = 0.0011), and Kety’s $K^{trans}$ (0.0401 ± 0.0360 vs 0.1198 ± 0.3048, p = 0.0471) and $V_e$(0.0900 ± 0.0307 vs. 0.1495 ± 0.0485, p = 0.0114). The area under the curve (AUC) for distinguishing between low LSF and high LSF was 0.87 for $\left|\mathit{u}\right|$, 0.80 for $V_e$ and 0.74 for $K^{trans}$. Noninvasive prediction of LSF is feasible from DCE MRI with QTM velocity postprocessing. Full article

This paper presents a strategy to design ultrawideband power amplifiers with a fractional bandwidth of approximately 200%. It exploits a simple output matching network, which consists of a series transmission line together with a shunt stub, to compensate the output parasitic network of the device. Following this, a multisection transformer is implemented to obtain the optimal load at the intrinsic drain plane. As design examples, several output matching networks were designed for two different size GaN HEMT devices. One of these examples was implemented and characterized, and a drain efficiency from 52% to 70% and an output power between 40 dBm and 42.5 dBm were obtained, over 67% of the 5G sub-6-GHz band (i.e., 0.1 to 4 GHz). The aforementioned results, to the best of the authors’ knowledge, represent the state of the art in broadband power amplifiers. Full article

Spiral waves are an intriguing phenomenon that can be found in a variety of chemical and biological systems. We consider the fractional-order resistor–capacitor shunted Josephson junction chaotic oscillator to investigate the spiral wave pattern. For a preliminary understanding, we look at the dynamics of isolated FJJs and show that infinitely coexisting periodic and chaotic attractors depend on the fractional order. In addition, we perform bifurcation analysis to show the dynamical transition of the attractors as a function of fractional order and basin stability analysis to show the infinitely coexisting attractors. This is followed by the existence of spiral waves which is observed under various intrinsic and extrinsic system parameters. Finally, the impact of noise on SW is also analyzed by dispersing it to the entire stimulation period or defined time-period. Full article