Ring-Split: Deadlock-Free Routing Algorithm for Circulant Networks-on-Chip.

This article considers the usage of circulant topologies as a promising deadlock-free topology for networks-on-chip (NoCs). A new high-level model, Newxim, for the exploration of NoCs with any topology is presented. Two methods for solving the problem of cyclic dependencies in circulant topologies, which limit their applications for NoCs due to the increased possibility of deadlocks, are proposed. The first method of dealing with deadlocks is universal and applicable to any topology; it is based on the idea of bypassing blocked sections of the network on an acyclic subnetwork. The second method-Ring-Split-takes into account the features of circulant topologies. The results of high-level modeling and comparison of the peak throughput of NoCs for circulant and mesh topologies using deadlock-free routing algorithms are presented. It was shown that a new approach for routing in circulants (compared to mesh topology) shows up to 59% better network throughput with a uniform distribution of network load.

True Efficacy of LAA Closure: Patient Outcomes on Long-term Single-Antiplatelet or No Therapy: Insights From the EWOLUTION Registry.

BACKGROUND: Left atrial appendage occlusion (LAAO) is recommended for patients with atrial fibrillation at increased stroke risk, where effective long-term oral anticoagulation (OAC) is not feasible. In order to assess long-term safety of LAAO with aspirin monotherapy or no therapy, we aimed to report on patients with the Watchman LAAO device (Boston Scientific) once postimplantation intensified antiplatelet or anticoagulation therapy is discontinued. METHODS: A total of 1025 patients scheduled for elective LAAO therapy prospectively consented for participation in the EWOLUTION registry; 1005 patients received a successful implant and were followed for 2 years. We identified 766 patients in EWOLUTION on single-antiplatelet therapy (SAPT; n = 639) or no therapy (n = 127) for ≥1 year following LAAO. RESULTS: Three to 6 months after LAAO, 766 patients were switched to SAPT or no therapy and were followed for at least 1 year until the study's conclusion or with events while on SAPT/ no therapy; mean time on SAPT/no therapy was 536.56 ± 177.59 days. Patients experienced 1.4 ischemic strokes per 100 patient years (PY) despite a CHA2DS2-VASC score of 4.3 ± 1.6. Major nonprocedural bleeding rates were low, with 1.3 major bleeds per 100 PY with a mean HAS-BLED score of 2.2 ± 1.2. Furthermore, the ischemic stroke rate in the SAPT/no-therapy subgroup was similar to the whole EWOLUTION collective and high-risk subgroups; the bleeding rate was even lower. When analyzed separately, strokes (2.1/100 PY) and bleedings (1.4/100 PY) of the no-therapy subgroup were similar to patients on SAPT (strokes 0.7/100 PY [P=.70]; bleedings 1.4/100 PY [P=.90]). CONCLUSIONS: Outcome data of patients on SAPT/no therapy for ≥1 year following Watchman implantation in the EWOLUTION registry suggest the efficacy and safety of LAAO.

Transverse Beam Emittance Measurement by Undulator Radiation Power Noise.

Generally, turn-to-turn power fluctuations of incoherent spontaneous synchrotron radiation in a storage ring depend on the 6D phase-space distribution of the electron bunch. In some cases, if only one parameter of the distribution is unknown, this parameter can be determined from the measured magnitude of these power fluctuations. In this Letter, we report an absolute measurement (no free parameters or calibration) of a small vertical emittance (5-15 nm rms) of a flat beam by this method, under conditions, when it is unresolvable by a conventional synchrotron light beam size monitor.

Impact of anticoagulation strategy after left atrial appendage occlusion in patients requiring direct current cardioversion.

INTRODUCTION: Current guidelines recommend adequate anticoagulation for at least 3 weeks pre- and 4 weeks post-direct current cardioversion (DCCV) to reduce thrombo-embolic risk in patients with atrial fibrillation (AF) lasting greater than 48 h. No specific recommendations exist for DCCV in patients that have undergone left atrial appendage occlusion (LAAO), many of whom are ineligible for anticoagulation. This study aims to observe the efficacy and safety of DCCV post-LAAO in everyday clinical practice. METHODS: This prospective multicenter registry included DCCVs in patients post-LAAO. Imaging strategy or anticoagulation treatment around DCCV were analyzed. Complications during 30-day follow-up were registered. DCCVs performed in accordance with current guidelines for the general AF population were compared to DCCVs performed deviating from these guidelines. RESULTS: In 93 patients (age 65 ± 17 years, CHA2 DS2 -VASC 3.0 ± 1.3) 284 DCCVs were performed between 2010 and 2018, in 271 sinus rhythm was restored. A wide variety of imaging or anticoagulation strategies around DCCV was observed; in 128 episodes strategies deviated from current guidelines. No thrombo-embolic events were observed after any DCCV during 30-day follow-up. In 34 DCCVs trans-esophageal echocardiography (TOE) was performed before DCCV to exclude cardiac thrombi and/or (re-)verify adequate device positioning. In two patients without post-LAAO imaging before DCCV, a device rotation or embolization was observed during scheduled TOE after LAAO. CONCLUSION: DCCV in AF patients after LAAO is highly effective. No thrombo-embolic events were observed in any patient in this observational cohort, regardless of the periprocedural anticoagulation or imaging strategy. Confirmation of adequate device positioning at least once before DCCV seems recommendable.

Routing in triple loop circulants: A case of networks-on-chip.

In this paper we propose and analyze various approaches to organizing routing in a triple loop circulant topologies as applied to networks-on-chip: static routing based on universal graph search algorithms, such as Dijkstra's algorithm and a possible implementation using Table routing; algorithms created analytically based on an engineering approach with taking into account the structural features of triple loop circulant graphs (Advanced clockwise, Direction selection); an algorithm created on the basis of a mathematical analysis of graph structure and solving the problem of enumerating coefficients at generators (Coefficients finding algorithm). Efficiency, maximum graph paths, occupied memory resources, and calculation time of the algorithms developed are estimated. Comparison of various variants of the algorithms is made and recommendations on their application for the development of networks-on-chip with triple loop circulant topologies are given. It is shown that Advanced clockwise and Direction selection algorithms guarantee that the packet reaches the destination node, but often in more steps than the shortest path. Nevertheless, they themselves are simpler and require less hardware resources than other algorithms. In turn, Coefficients finding algorithm has great computational complexity, but is optimal and, in comparison with Dijkstra's algorithm, is much simpler for RTL implementation which reduces network-on-chip routers resources cost.

Development of routing algorithms in networks-on-chip based on two-dimensional optimal circulant topologies.

This work is devoted to the study of application of new topologies in the design of networks-on-chip (NoCs). It is proposed to use two-dimensional optimal circulant topologies for NoC design, and it is developed an optimized routing algorithm with the decreased memory usage. The proposed routing algorithm was compared with Table routing, Clockwise routing, and Adaptive routing algorithms, previously developed for ring circulant topologies, and specialized routing algorithm for multiplicative circulants. The results of synthesis of routers implementing proposed routing algorithms are presented. The cost of ALM and register resources for the implementation of communication subsystems in NoCs with circulant topologies is estimated.

Combining left atrial appendage closure and catheter ablation for atrial fibrillation: 2-year outcomes from a multinational registry.

AIMS: Clinical practice guidelines do not recommend discontinuation of long-term oral anticoagulation in patients with a high stroke risk after catheter ablation for atrial fibrillation (AF). Left atrial appendage closure (LAAC) with Watchman has emerged as an alternative to long-term anticoagulation for patients accepting of the procedural risks. We report on the long-term outcomes of combining catheter ablation procedures for AF and LAAC from multicentre registries. METHODS AND RESULTS: Data were pooled from two prospective, real-world Watchman LAAC registries running in parallel in Europe/Middle-East/Russia (EWOLUTION) and Asia/Australia (WASP) between 2013 and 2015. Of the 1140 patients, 142 subjects at 11 centres underwent a concomitant AF ablation and LAAC procedure. The mean CHA2DS2-VASc score was 3.4 ± 1.4 and HAS-BLED score 1.5 ± 0.9. Successful LAAC was achieved in 99.3% of patients. The 30-day device and/or procedure-related serious adverse event rate was 2.1%. After a mean follow-up time of 726 ± 91 days, 92% of patients remained off oral anticoagulation. The rates of the composite endpoint of ischaemic stroke/transient ischaemic attack/systemic thromboembolism were 1.09 per 100 patient-years (100-PY); and for non-procedural major bleeding were 1.09 per 100-PY. These represent relative reductions of 84% and 70% vs. expected rates per risk scores. CONCLUSION: The long-term outcomes from these international, multicentre registries show efficacy for all-cause stroke prevention and a significant reduction in late bleeding events in a population of high stroke risk post-ablation patients who have been withdrawn from oral anticoagulation.

Development of routing algorithms in networks-on-chip based on ring circulant topologies.

This work is devoted to the study of communication subsystem of networks-on-chip (NoCs) development with an emphasis on their topologies. The main characteristics of NoC topologies and the routing problem in NoCs with various topologies are considered. It is proposed to use two-dimensional circulant topologies for NoC design, since they have significantly better characteristics than most common mesh and torus topologies, and, in contrast to many other approaches to improving topologies, have a regular structure. The emphasis is on using ring circulants which although in some cases have somewhat worse characteristics than the optimal circulants, compensate by one-length first generatrix in such graphs that greatly facilitate routing in them. The paper considers three different approaches to routing in NoCs with ring circulant topology: Table routing, Clockwise routing, and Adaptive routing. The algorithms of routing are proposed, the results of synthesis of routers, based on them, are presented, and the cost of chip resources for the implementation of such communication subsystems in NoCs is estimated.

Combined atrial fibrillation ablation and left atrial appendage closure: long-term follow-up from a large multicentre registry.

Aims: Long-term freedom from atrial fibrillation (AF) after catheter ablation (CA) and consequently the potential for stroke reduction remain unpredictable. Percutaneous left atrial appendage closure (LAAC) is an effective mechanical alternative to oral anticoagulation (OAC) for stroke prevention in AF patients. This study aims to evaluate long-term clinical results of combined CA and LAAC in one single procedure. Methods and results: Patients with non-valvular AF who underwent combined CA and LAAC procedure were included in the retrospective compilation of independent prospective general LAAC registries at the individual centres. Transoesophageal echocardiography (TOE) was used to evaluate device position and LAA sealing. Between 2009 and 2015, 349 patients with AF (58% male, age 63.1 ± 8.2 years; score for stroke prediction in AF patients (CHA2DS2-VASc) 3.0; score for major bleeding in patients on anticoagulation (HAS-BLED) 3.0; 56% paroxysmal AF) were included. Indications for LAAC included previous stroke (38%), history of bleeding (22%), and physician/patient preference (29%). Periprocedural complications up to 30 days included pericardial effusion (1.5%) and one minor stroke (0.3%) but no death. After 6 weeks, TOE showed successful sealing of the LAA in 98.9%. After 35 months of follow-up, 51% of patients had AF recurrence. A total of nine ischaemic strokes were recorded, resulting in an annualized stroke rate of 0.9% compared to an expected stroke rate of 3.2% without anticoagulation and combined treatment. Conclusion: This large pooled multicentre analysis of five prospective registries shows that combining CA and LAAC is feasible, safe, and successful. Long-term follow-up shows greatly reduced stroke and bleeding rates despite recurrence of AF in more than half of the patients.

Combining Watchman left atrial appendage closure and catheter ablation for atrial fibrillation: multicentre registry results of feasibility and safety during implant and 30 days follow-up.

Aims: Long-term results from catheter ablation therapy for atrial fibrillation (AF) remain uncertain and clinical practice guidelines recommend continuation of long-term oral anticoagulation in patients with a high stroke risk. Left atrial appendage closure (LAAC) with Watchman has emerged as an alternative to long-term anticoagulation for patients accepting of the procedural risks. We report on the initial results of combining catheter ablation procedures for AF and LAAC in a multicentre registry. Methods and results: Data were pooled from two prospective, real-world Watchman LAAC registries running in parallel in Europe/Middle-East/Russia (EWOLUTION) and Asia/Australia (WASP) between 2013 and 2015. Of the 1140 patients, 139 subjects at 10 centres underwent a concomitant AF ablation and LAAC procedure. The mean CHA2DS2-VASc score was 3.4 ± 1.4 and HAS-BLED score 1.5 ± 0.9. Successful Watchman implantation was achieved in 100% of patients. The overall 30-day serious adverse event (SAE) rate was 8.7%, with the device and/or procedure-related SAE rate of 1.4%. One pericardial effusion required percutaneous drainage, but there were no strokes, device embolization, or deaths at 30 days. The 30-day bleeding SAE rate was 2.9% with 55% of patients prescribed NOAC and 38% taking warfarin post-procedure. Conclusion: The outcomes from these international, multicentre registries support the feasibility and safety of performing combined procedures of ablation and Watchman LAAC for patients with non-valvular AF and high stroke risk. Further data are needed on long-term outcomes for the hybrid technique on all-cause stroke and mortality.