Single Radio Frequency Research Articles

Effects of intralesional pulsed radiofrequency treatment on pain in patients with calcaneal spur: results of 460 patients

BackgroundThis study aimed to investigate the efficacy of intralesional pulsed radiofrequency (RF) in the treatment of calcaneal spur and the results of patients who underwent single and double sessions of RF treatment.MethodsThe population of this retrospective study consisted of 460 patients who were diagnosed with calcaneal spur with clinical examination and direct radiography. The Wong-Baker Faces Pain Rating Scale and The American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Score were used to determine the pain status and functional capacities of the patients. Posttreatment evaluation was carried out on average in the 6th week.ResultsThe study involved 460 patients, 76.9% of whom were female, with the average age of 50.8 ± 10.9 years in total. Of the patients 43% was given RF therapy in a single session, and 57% of them in double sessions. After the RF procedure, the number of patients whose pain decreased according to both AOFAS and Wong-Baker pain scoring systems increased statistically significantly (p < 0.001). There was a statistically significant increase in the AOFAS-pain scores and the total AOFAS scores and a significant decrease in the Wong Baker-pain scale after treatment. However, there was no significant change in treatment success with respect to the number of RF sessions. Although not statistically significant, the differences in the AOFAS-pain scores and in the total AOFAS scores were found to be higher in patients who underwent single session RF, while the difference in the Wong Baker-pain ranking was higher in patients who received double sessions RF.ConclusionIntralesional pulsed RF procedure can be preferred as a relatively less invasive method that does not have any serious complications in patients with persistent calcaneal spurs who do not respond to the use of oral anti-inflammatory drugs and shoe insoles, nor corticosteroid injection to the lesion area.

Single Entry Posterior Parasagittal Approach Radiofrequency Neurotomy of Cervical Medial Branch: A Feasible Alternative to Conventional Approaches in the Treatment of Cervical Facet Pain.

Cervical facet joint pain is an important cause of chronic neck pain. The recommended treatment for this condition is radiofrequency (RF) neurotomy of the medial branch of dorsal rami. There have been attempts to find safe and effective ways to perform this procedure. The objective of this study is to describe the single entry posterior parasagittal approach and to evaluate the efficacy and safety of this approach compared to the conventional posterolateral approach of RF neurotomy of cervical medial branch. The record of all patients with cervical facet pain who were treated with RF neurotomy medial branch of dorsal rami between January 2016 and December 2019 were reviewed retrospectively. Comparisons were made between patients who underwent RF neurotomy with multiple skin entry posterolateral approach and those who underwent RF neurotomy with single entry posterior parasagittal approach. The primary outcome was measured as the mean changes in numerical rating scale (NRS), and the secondary outcomes were duration and complications related to both approaches. Thirty-one patients who underwent RF neurotomy via posterolateral approach were compared with 40 patients who underwent the procedure via posterior parasagittal approach. Both approaches showed a significant decrease in the NRS from baseline values. However, the differences in the NRS lowering effect at 3 and 12 months between these 2 approaches were not statistically significant. The duration of the procedure was significantly shorter with posterior parasagittal approach (44.13 ± 4.72 minutes vs 54.68 ± 7.39 minutes; P < 0.001). There were no serious complications encountered in both approaches. With comparable efficacy and safety profile between the posterior parasagittal and the conventional posterolateral approaches, the former single skin entry approach offers the added advantage of being less time-consuming. Further randomized prospective studies are necessary to validate these findings.

Single-Channel Spatial Spectrum Estimation Direction Finding by the Time-Modulated Linear Array

In this letter, a novel direction-finding method with spatial spectrum estimation is proposed and verified, based on the time-modulated linear array (TMLA) and a single radio-frequency channel. Its principle is as follows. The TMLA receives and periodically modulates the incident signal. After the power combiner, the modulated signal is down-converted to the intermediate frequency and sampled in the single-channel receiver. In the digital domain, the array manifold vector can be calculated from the Fourier coefficients and the harmonic characteristic matrix related to modulation sequences, and thus, the autocorrelation matrix can be estimated. Afterward, the multiple signal classification algorithm is applied to estimate the incident angle, and the spatial smoothing method is exploited to deal with the direction finding of coherent sources. The proposed method has a simple structure and low computational complexity. Numeric simulations and corresponding experiments have been conducted to verify its effectiveness.

NOMA with optimal transmit antenna selection scheme with self adaptive metaheuristic model

AbstractNonorthogonal multiple access (NOMA) constitutes a promising technique in the fifth‐generation (5G) mobile networks. On the transmitter side, the concurrent usage of multiple antennas needs an appropriate count of parallel Radio Frequency (RF) chains at the front end. Owing to this consequence, it maximizes the power consumption, cost, and system complexity along with maximization in the antenna count. In order to tackle these aforesaid problems, some researchers prefer the Transmit Antenna Selection (TAS) for modeling the transmitter structure simple. The best antenna is selected opportunistically by an efficient TAS technique from multiple antennas and deploys a single RF chain for transmission. In this paper, a novel approach for optimized antenna selection in overlay CR networks using NOMA and SM is proposed via the usage of optimization tactics. To choose the desired respective antenna, this paper introduces a new Mean and Median Fitness Centered Moth flame Optimization (MM‐FCMO), which is the modified Moth Flame Optimization (MFO) Algorithm, which taken the core objectives such as power consumption and Mean Square Error (MSE). The MSE and power consumption of the chosen antennas have to be lower for the system to attain maximum antenna gain with lower noise. Finally, to exhibit that the presented work is much significant than the traditional works, a comparative analysis is made in terms of error minimization and statistical evaluation.

A Fully Integrated Cryo-CMOS SoC for State Manipulation, Readout, and High-Speed Gate Pulsing of Spin Qubits

This article presents a fully integrated Cryo-CMOS system on chip (SoC) for quantum computing. The proposed SoC integrates a radio frequency (RF) pulse modulator for qubit state manipulation, a multi-tone signal generator and a coherent receiver for qubit state readout, and 22 DACs for high-speed voltage pulsing of qubit gates. By adopting frequency division multiplexing and direct digital synthesis (DDS), the RF pulse modulator can control up to 16 qubits over a single RF line, and the readout receiver can detect the state of up to six qubits simultaneously. The proposed SoC also integrates a microcontroller for low latency on-chip signal processing and increased flexibility in implementing quantum instruction sets. A detailed analysis of qubit-state readout fidelity and the impact of finite DAC resolution on two-qubit gate fidelity is also included in this article, together with an electrical specification summary. The SoC is implemented in Intel’s 22 nm FFL fin field-effect transistor (FinFET) process, and it is characterized both at room and 4 K temperatures. The performance of each specific block is measured, with the readout characterized in a loop-back configuration. Generation of the control signals required for a full Rabi oscillation experiment is also demonstrated. This article also describes the cryogenic thermalization techniques used to integrate the SoC in the dilution refrigerator and shows temperature measurements during operation.

Water-based devices for advanced control of electromagnetic waves

Tunable devices are of great interest as they offer reconfigurability to their operation, although many of them employ rare and expensive materials. In a world with increasing focus on ecological compatibility and recyclability, immense efforts are being made to find bio-friendly alternatives. However, in some cases, one does not have to look far, because water, a high-permittivity dielectric at microwave frequencies, is readily available. Recent studies have shown that compact Mie resonators, which are the fundamental blocks in all-dielectric metamaterials and dielectric resonator antennas, can be realized with small water elements. In a variety of applied physics areas, encompassing frequencies from the radio to the optical parts of the spectrum, all-dielectric implementations have received immense attention. When it comes to water, its temperature-dependent permittivity and liquidity enable a multitude of unprecedentedly simple means to reconfigure and tune the resulting devices. Moreover, being a polar solvent, water easily dissolves various physiologically important electrolytes, which potentially can be exploited in a sensor design. Presently, we review water-based devices for advanced microwave control and sensing. We show and discuss the dynamic properties of water and examine the microwave scattering and absorption characteristics of single water elements. We investigate how such water elements can be employed in various microwave designs, including single resonators, metamaterials, metasurfaces, antennas, absorbers, and radio frequency components. The main complications of water are its losses, especially at higher microwave frequencies, and its stability. We discuss how to overcome these and show that even highly loss-sensitive modes, namely, toroidal modes and bound states in the continuum, can be realized with water-based devices. We believe that water-based devices usher the route to meet the UN proclaimed goals on global sustainability and human-friendly environment.

Spatial Modulation for RIS-Assisted Uplink Communication: Joint Power Allocation and Passive Beamforming Design

In this paper, we investigate the uplink communication of a reconfigurable intelligent surface (RIS) assisted system, in which an user equipment (UE) with single radio frequency (RF) chain delivers information to an access point (AP) by adopting the spatial modulation (SM). Specifically, we first investigate the transmit SM (TSM) scheme and jointly optimize the UE’s power allocation matrix and the RIS reflection coefficients to enhance the system reliability. We formulate a non-convex optimization problem to reduce the system symbol-error-rate (SER) and propose a novel penalty-alternative optimizing algorithm to obtain a near-optimal solution. Following this, we show that with the assistant of RIS, receive SM (RSM) scheme can also be performed even if the UE has only one RF chain. Based on this observation, a novel RIS-assisted RSM scheme is proposed, which can provide a low cost and complexity solution for system realization. The reflection coefficients of the RIS are also optimized for the proposed RSM. Numerical results show that the RIS-assisted TSM can achieve a lower SER than the conventional communication scheme (CTS) without SM and the proposed RSM scheme has lower detection complexity than that of CTS. It is also shown that the performance of the TSM and RSM schemes is more sensitive to the quantization accuracy of the phase of the RIS coefficients than that of the amplitude.

Demonstration of fast multi-slice quasi-steady-state chemical exchange saturation transfer (QUASS CEST) human brain imaging at 3T.

To combine multi-slice chemical exchange saturation transfer (CEST) imaging with quasi-steady-state (QUASS) processing and demonstrate the feasibility of fast QUASS CEST MRI at 3T. Fast multi-slice echo planar imaging (EPI) CEST imaging was developed with concatenated slice acquisition after single radiofrequency irradiation. The multi-slice CEST signal evolution was described by the spin-lock relaxation during saturation duration (Ts ) and longitudinal relaxation during the relaxation delay time (Td ) and post-label delay (PLD), from which the QUASS CEST was generalized to fast multi-slice acquisition. In addition, numerical simulations, phantom, and normal human subjects scans were performed to compare the conventional apparent and QUASS CEST measurements with different Ts , Td, and PLD. The numerical simulation showed that the apparent CEST effect strongly depends on Ts , Td , and PLD, while the QUASS CEST algorithm minimizes such dependences. In the L-carnosine gel phantom, the proposed QUASS CEST effects (2.68 ± 0.12% [mean ± SD]) were higher than the apparent CEST effects (1.85 ± 0.26%, p < 5e-4). In the human brain imaging, Bland-Altman analysis bias of the proposed QUASS CEST effects was much smaller than the PLD-corrected apparent CEST effects (0.03% vs. -0.54%), indicating the proposed fast multi-slice CEST imaging is robust and accurate. The QUASS processing enables fast multi-slice CEST imaging with minimal loss in the measurement of the CEST effect.

B-PO05-138 CATHETER ABLATION OF ATRIAL FIBRILLATION IS NOT ASSOCIATED WITH DESTRUCTION OF CARDIAC AFFERENTS DRIVING VOLUME-REGULATING AUTONOMIC REFLEXES

We have previously shown abnormal cardiac volume-sensitive reflexes (whose receptors are co-located in veno-atrial tissue) in AF patients. Whether unintended nerve disruption from Pulmonary Vein Isolation (PVI) could also occur is unknown. To evaluate whether PVI disrupts afferent volume-sensitive reflexes. We consecutively studied paroxysmal/persistent AF patients pre-PVI (n =18) and recontacted them for a post-PVI visit. We excluded those with AF recurrence/procedural complications, allowing redo procedures if AF-free >6 months. A cohort of 9 patients consented to both visits. We measured beat-to-beat mean arterial pressure (MAP) and heart rate (HR) continuously while testing reflex vasoconstriction from Lower Body Negative Pressure (LBNP), which offloads veno-atrial volume receptors, using forearm blood flow (FBF∝1/vascular resistance), at 0, -20 & -40 mmHg LBNP by venous occlusion plethysmography. We withheld anti-hypertensives/arrhythmics (5 half-lives). Mean age was 64±3 years; 78% male; BMI 28±1 kg/m2; LA size 37±2 ml/m2; and left ventricular function 65±3 %. We performed single ring radiofrequency PVI (PV and posterior wall, n=7); cryoablation (n=1) and wide antral PVI (n=1). Redo in n=2. During LBNP, MAP decreased slightly both pre (-1.6±3%) and post-PVI (-2.8±1.8%); P=0.7. HR increased similarly (P=0.7) pre (10.6±6.4%) and post-PVI (7.2±1.5%). FBF was unchanged (P=0.8), Figure. The reflex response to decreased cardiac volume is not altered by PVI. More work to assess other lesion sets or ganglionated plexi ablation is needed to ensure absence of adverse autonomic remodelling due to catheter ablation for AF.

Clinical efficacy of repeated intra-articular pulsed radiofrequency for the treatment of knee joint pain and its effects on inflammatory cytokines in synovial fluid of patients.

The application value of repeated intra-articular pulsed radiofrequency for the treatment of knee joint pain has remained to be determined. To investigate this, a total of 64 patients with chronic knee joint pain admitted to Caoxian People's Hospital (Caoxian, Chine) between October 2016 and May 2018 were enrolled in the present study and analyzed prospectively. The patients were randomly divided into a control group, receiving treatment with a single intra-articular pulsed radiofrequency through the knee joint (n=32), and an experimental group, receiving multiple intra-articular pulsed radiofrequency treatments through the knee joint (n=32). The visual analog scale score (VAS), clinical efficacy and adverse reactions prior to and after treatment were compared between the two treatments. Synovial fluid cytokines were measured using ELISA prior to and after treatment. After the treatment, the control group and the experimental group both had a lower VAS (P<0.001) and the control group had a higher VAS and lower pain relief than the experimental group (P<0.001). The control group had a total effectiveness rate of 78.13%, with 13 patients experiencing complete relief (40.63%), 12 patients exhibiting a marked improvement (37.5%) and 7 patients reporting no effects (21.87%). The experimental group had a total effectiveness rate of 90.63%, with 18 patients (56.25%) being cured, 11 patients having a marked effect (34.37%) and 3 patients reporting no effects (9.38%). The experimental group had a higher incidence of adverse reactions than the control group (P<0.05). After treatment, the two groups had decreased IL-6, IL-10 and TNF-α levels in the knee joint synovial fluid (P<0.05), with the experimental group having lower cytokine levels than the control group (P<0.05). These results indicated that repeated intra-articular pulsed radiofrequency is an effective method for the treatment of knee joint pain and may be used in clinical practice.

The incidence and location of epicardial connections in the era of contact force guided ablation for pulmonary vein isolation.

The effects of epicardial connections (ECs) involving pulmonary veins (PVs) in atrial fibrillation (AF) ablation have been revealed recently. However, no systematic approaches to identify and ablate the ECs were established. Patients with AF undergoing radiofrequency (RF) catheter ablation were retrospectively analyzed. ECs were identified when (1) PV isolation (PVI) cannot be achieved after first-pass isolation; (2) PVI was still absent although the conduction gap was detected and ablated; (3) the earliest activation area (EAA) was revealed located within the PV antrum distant from the initial ablation line using high-density mapping (HDM) technique; (4) focal ablation at the EAA was effective to achieve PVI. Relevant pacing maneuvers were performed to elucidate ECs' bidirectional conduction. Overall, 36 ECs were identified and ablated in 35/597 (5.86%) patients. Among the 35 patients with ECs, at least one PV insertion of ECs was located at the carina region. The most common pattern was a single breakthrough in 31 (88.6%) patients, followed by multiple breakthroughs in 3 and wide breakthroughs in 1. The median distance from EAA to the initial ablation line was 10.0 mm. The average number of RF energy delivery was 1.75 ± 1.00, and single RF delivery was adequate in 16/36 (44.4%) patients. Continuous potentials were present at the EAA in 9/34 (26.5%) patients. ECs were confirmed and ablated successfully in 5.86% (35/597) AF patients using HDM. PV insertions of ECs were mainly located at the carina region. Continuous potentials might assist in the prediction of ECs.

A Survey for Recent Techniques and Algorithms of Geolocation and Target Tracking in Wireless and Satellite Systems

A single Radio-Frequency Interference (RFI) is a disturbance source of modern wireless systems depending on Global Navigation Satellite Systems (GNSS) and Satellite Communication (SatCom). In particular, significant applications such as aeronautics and satellite communication can be severely affected by intentional and unintentional interference, which are unmitigated. The matter requires finding a radical and effective solution to overcome this problem. The methods used for overcoming the RFI include interference detection, interference classification, interference geolocation, tracking and interference mitigation. RFI source geolocation and tracking methodology gained universal attention from numerous researchers, specialists, and scientists. In the last decade, various conventional techniques and algorithms have been adopted in geolocation and target tracking in civil and military operations. Previous conventional techniques did not address the challenges and demand for novel algorithms. Hence there is a necessity for focussing on the issues associated with this. This survey introduces a review of various conventional geolocation techniques, current orientations, and state-of-the-art techniques and highlights some approaches and algorithms employed in wireless and satellite systems for geolocation and target tracking that may be extremely beneficial. In addition, a comparison between different conventional geolocation techniques has been revealed, and the comparisons between various approaches and algorithms of geolocation and target tracking have been addressed, including H∞ and Kalman Filtering versions that have been implemented and investigated by authors.

Computation of Phase Noise Spectrum in Optoelectronic Oscillator

A method for the phase noise characterization of single-loop optoelectronic oscillators (OEO) is presented. Based on the injection-pulling dynamics of OEO under radio frequency (RF) signal injection, this method is used to compute the phase noise spectrum of a free-running single-loop OEO. From the injection locking equation, the expression for the output RF spectrum of single-loop OEO under the influence of a single sinusoidal RF signal injection is derived and this analysis is then utilized to study the RF output power spectrum of the single-loop OEO when injected by two weak and equally strong RF sinusoidal signals with mirror frequencies with respect to the free-running frequency of the OEO. An expression for the far-out phase noise spectrum of a free-running single-loop OEO is presented to capture the far-out phase noise characteristics of the OEO. Also, we derive the expression for the close-in phase noise spectrum of the free-running single-loop OEO by considering the multiplicative noise as the overall loop-gain perturbation in the OEO loop. The experimental results are also given in partial support to the conclusions of the analysis.

Design and analysis of an amplitude-phase weighting module for harmonic beamforming in time-modulated antenna arrays

Amplitude-phase weighting modelling and analysis are indispensable for the performance evaluation of a practical, nonideal time-modulated antenna array (TMA). This paper investigates the effective performance evaluation of a crucial component in TMAs, named the time-modulated amplitude-phase weighting (TMAPW) module, while its performance is analysed through a single radio frequency (RF) channel and radiation patterns. A mathematical model is developed for amplitude-phase evaluation with nonideal time modulation sequence (TMS). A comparative measurement methodology is proposed to directly measure the attenuated amplitude and shifted phase at harmonic frequencies. Experimental validation for the developed mathematical model is carried out through an X-band prototype of the TMAPW module. Harmonic beamforming is then analysed in a 32-element nonideal TMA. Based on the developed model, the nonideal TMS can accurately evaluate the attenuated amplitude, shifted phase, and power spectrum leakage effect of the fabricated TMAPW module. Moreover, the sidelobe level (SLL) errors in radiation patterns are reduced with the proposed nonideal TMS. Consequently, the developed mathematical model and the measurement methodology will benefit the accurate performance evaluation of nonideal TMAs.

The magnitude and the course of local impedance drop to guide successful AF ablation: insight from an Italian registry

Abstract Funding Acknowledgements Type of funding sources: None. Background It has been demonstrated that an ablation strategy based on local impedance (LI) algorithm is helpful in guiding successful ablation of atrial fibrillation (AF) cases. How the magnitude and the course of LI drop could impact the effectiveness of ablation has to be proved. Purpose We aimed to evaluate LI drop characteristics in predicting effective radiofrequency (RF) ablation of consecutive AF cases. Methods Consecutive patients undergoing AF ablation at 8 Italian centers were included in the CHARISMA registry. A RF ablation catheter equipped with mini-electrodes technology and a dedicated algorithm was used to measure LI and to guide ablation. For our purpose, we defined the time to drop (τ) as the time for the first deflection of LI drop to the plateau. RF applications were targeted to a LI drop of 10 Ω and were stopped when a maximum cut-off LI drop of &amp;lt;40 Ω was observed. Successful single RF ablation was defined according with a reduction of signal voltage by at least 50% and inability to capture local tissue on pacing. The ablation endpoint was PVI as assessed by entrance and exit block. Follow-up were scheduled at 3, 6 and 12 months post-ablation. Results 153 consecutive patients (61% paroxysmal AF, 39% persistent AF) were enrolled in the study. 3556 point-by-point first-pass RF applications of &amp;gt;10 s duration were performed around PVs. The mean LI drop was 13 ± 8Ω, the mean τ was 18.7 ± 13s and the median LI drop/τ was 0.67 [QI-QIII, 0.37 – 1.17] Ω/s. Both absolute drops in LI and LI drop/τ were greater at successful ablation sites (n = 3122, 88%) than at ineffective ablation sites (n = 434, 12%) (14 ± 8Ω vs 6 ± 4Ω, p &amp;lt; 0.0001 for LI; 0.73[0.41–1.25]Ω/s vs 0.35[0.22–0.59]Ω/s for LI drop/τ, p &amp;lt; 0.0001). Every 5-point increment in LI drop was associated with successful ablation, with an OR of 3.13 (95%CI: 2.7 to 3.6, p &amp;lt; 0.0001), reaching the highest point when a value larger than 15 Ω was observed (99.9% of acute success). A significant trend was observed from lower to higher LI drop/τ values and a value greater than 0.65 Ω/s (best cut-off value on the basis of the ROC analysis) was significantly associated with successful RF delivery with an OR of 5.54 (95%CI: 4.31 to 7.11, p &amp;lt; 0.0001). No complications occurred during and after procedures. At 1-year follow-up, the AF recurrence rate was 12% after the 90-day blanking period. Conclusions The magnitude and time-course of the LI drop during RF delivery were associated with effective lesion formation. This ablation strategy for PVI guided by LI technology proved safe and effective, and resulted in a very low rate of AF recurrence over 1-year follow-up.

Efficacy and safety of a high power short duration ablation-index guided protocol for pulmonary vein isolation using a single catheter

Abstract Funding Acknowledgements Type of funding sources: None. Background Catheter ablation for atrial fibrillation (AF) is the most common performed electrophysiological procedure. The cost of this procedure remains high. Purpose To improve health care utilization, we aimed to compare the efficacy and safety of a minimalistic, streamlined single radiofrequency catheter ablation approach using high power short duration ablation-index guided protocol (HPSD) vs. a standard single catheter protocol. Methods A circular mapping catheter free PVI with a single transseptal puncture was performed in 91 patients. A CARTO fast anatomical map was performed with the ablation catheter. Pacing maneuvers were used to confirm exit block. Procedural characteristics and success rates were compared using HPSD- vs. a standard ablation-protocol. Freedom from recurrence was defined as a 1-year absence of AF episodes &amp;gt; 30 s, beyond the 3-month-blanking-period. Results Using the HPSD-protocol the median procedure, map and RF ablation time were significantly shorter in the HPSD group compared to the standard group, 84 (IQR 76-100) vs. 118 minutes (IQR 104-141), 12 (IQR 10-16) vs. 18 minutes (IQR 15-21) and 1036 (898-1184) vs. 1949 seconds (IQR 1693-2261), respectively, P &amp;lt; .001 for all. First-pass-PVI was achieved using the HPSD-protocol in 23 patients (74%) and the standard-protocol in 30 patients (53%), p = 0.08. Localization of conduction gaps are illustrated for the HPSD-protocol and the standard-protocol in Figure 1. The residual gap was identified using the ablation catheter only in all patients. No procedural complication were observed. At 12 months follow-up, 60 (89.6%) patients remained free from AF with no differences between groups. Conclusions A minimalistic, CMC-free HPSD-guided PVI approach is very efficient, safe, likely cost-saving, and associated with excellent clinical outcomes at 1 year. Abstract Figure 1

Double loop ventricular tachycardia activation patterns with single loop mechanisms: Asymmetric entrainment responses during "pseudo-figure-of-eight" reentry.

The classical paradigm of scar-related reentrant ventricular tachycardia (VT) features a circuit with a double loop figure-of-eight (F8) activation pattern. The purpose of this study was to interrogate VT circuits with F8 activation patterns by entrainment mapping to differentiate an active loop from a passive loop. Sixty VT circuits with >90% of tachycardia cycle length delineated in high resolution were retrospectively analyzed in 55 patients (nonischemic 49%). A pseudo-F8 VT circuit was defined as a double loop activation pattern driven by a single loop mechanism with a passive loop that yields a long postpacing interval (postpacing interval - tachycardia cycle length ≥ 30 ms). Single loop activation patterns were observed in 33% (n = 20). Of 40 circuits with F8 patterns by activation mapping, 20 were studied with entrainment mapping, where a passive loop was identified by a long postpacing interval in 50%. In 6 circuits where entrainment mapping was performed from both outer loop regions, all demonstrated asymmetric responses to entrainment, confirming a single loop mechanism. Entrainment from both lateral margins of the common pathway (n = 7) demonstrated an asymmetric response in 29%. In all pseudo-F8 circuits (n = 10), the shorter loop functioned as the active loop and ablation targeting the active loop side of the isthmus resulted in VT termination with a single radiofrequency application. In a selected cohort, single loop mechanisms are more prevalent than double loop reentry in reentrant human VT. Half of VT circuits with double loop activation patterns can be demonstrated to be sustained by a single active loop mechanism by entrainment mapping. Ablation targeting the shorter active loop resulted in rapid termination during radiofrequency application.

Multi-cell, Multi-user, and Multi-carrier Secure Communication Using Non-Orthogonal Signals’ Superposition with Dual-Transmission for IoT in 6G and Beyond

Considering the advancements of the internet of things (IoT) in 6G and beyond communications, data transmission security in IoT devices has received extensive interest because of their significant features, such as low computational complexity, led by low power requirements. In such devices, the conventional cryptographic techniques may fail to provide secure communication. To fight this drawback, physical layer security (PLS) has remarkable potential to provide security solutions suitable for such applications. In this work, a highly effective PLS technique is proposed for providing secure communication against external and internal eavesdroppers in a downlink multi-cell, multi-user, and multi-carrier IoT communication system. In our proposed system, we considered two base stations, where each base station uses a single radio frequency (RF) chain to link two antennas that are used for the transmission of data. Further, we transmit the data in two rounds, and each round of transmission occurs through a single active antenna of each base station. A different antenna is used for each round of transmission to communicate with two single antenna IoT devices/users in the presence of a passive eavesdropper. In the proposed algorithm, frequency selective channel-based pre-coder matrices and the dual transmission approach are jointly employed. The dual-transmission is performed simultaneously from two base stations to provide security against internal and external eavesdroppers. The proposed system is suitable for IoT-based applications. Also, the potential capabilities of our proposed algorithm are proved by extensive mathematical and simulation analysis.

Comparative study on the dynamics and the composition between a pulsed laser deposition (PLD) and a plasma enhanced PLD (PE-PLD)

We report the effect of single and dual radio frequency (RF) plasma discharge on the composition and dynamics of a titanium plasma plume produced in a plasma-enhanced pulsed laser deposition (PE-PLD) system. The study was carried out in a nitrogen environment at different pressures. Time-resolved images, optical emission spectroscopy, and interferometry were employed to analyze the plasma. We were able to fit time-resolved images using different expansion models, obtained an expansion velocity between 6 and 30 × 103 m/s. Emission lines from N II, Ti II, were observed by changing the pressure and RF conditions. An increase in emission line intensity from N II was observed by increasing the pressure and RF power. We used Ti II lines to estimate the plasma temperature by using the Boltzmann equation, and we obtained the density from the Ti II line (454.9 nm) through Stark broadening. In addition, a Mach-Zehnder interferometer was employed to make a two-dimensional map of the electron density at early times. The estimated temperatures and densities are between 0.8 and 2.0 eV and 1017 – 1018 cm−3, respectively. The results suggest that increasing RF power enhanced the Ti-N atoms interaction, which is crucial in titanium nitride film applications.

Photonic generation and theoretical investigation of phase noise in quadrupling and 12-tupling millimeter wave Signal using optical self-heterodyne system

In this paper, photonic generation of quadrupling and twelve-tupling millimeter wave signal using single radio frequency (RF) signal is proposed. The purity of generated signal is observed by using mathematical approach which is further verified on simulation platform. Cascaded DP-DDMZM configuration is used in the proposed optical self- heterodyne system to generate millimeter-wave signals four times and twelve times the input RF source frequency. Selective sideband generation and carrier suppression techniques are utilized to generate the desired RF signal at the photodetector. Furthermore, the phase noise analysis of the generated millimeter wave signal is theoretically investigated. Expression of power spectral density for 40 GHz and 120 GHz millimeter signal is mathematically calculated to observe how the spectral quality is affected by the random phase fluctuations of input RF and optical sources. Phase noise of the millimeter-wave signal for different optical path length difference at various offset frequency is compared and discussed. System parameters such as noise figure, insertion loss, and spurious-free dynamic range (SFDR) are calculated for generated millimeter-waves/RF signals. The present proposed system uses a single RF source to generate quadrupling and 12-tupling millimeter wave and find its application in WDM systems, optical signal processing, radar system, etc. The results can be used to build an opto-electronic oscillator for a high-frequency microwave photonic communication system.