Evaluation of MU-MIMO Digital Beamforming Algorithms in B5G/6G LEO Satellite Systems

Satellite Communication (SatCom) systems will be a key component of 5G and 6G networks to achieve the goal of providing unlimited and ubiquitous communications and deploying smart and sustainable networks. To meet the ever-increasing demand for higher throughput in 5G and beyond, aggressive frequency reuse schemes (i.e., full frequency reuse), combined with digital beamforming techniques to cope with the massive co-channel interference, are recognized as a key solution. Aimed at (i) eliminating the joint optimization problem among the beamforming vectors of all users, (ii) splitting it into distinct ones, and (iii) finding a closed-form solution, we propose a beamforming algorithm based on maximizing the users' Signal-to-Leakage-and-Noise Ratio (SLNR) served by a Low Earth Orbit (LEO) satellite. We investigate and assess the performance of several beamforming algorithms, including both those based on Channel State Information (CSI) at the transmitter, i.e., Minimum Mean Square Error (MMSE) and Zero-Forcing (ZF), and those only requiring the users' locations, i.e., Switchable Multi-Beam (MB). Through a detailed numerical analysis, we provide a thorough comparison of the performance in terms of per-user achievable spectral efficiency of the aforementioned beamforming schemes, and we show that the proposed SLNR beamforming technique is able to outperform both MMSE and ZF schemes in the presented SatCom scenario

Evaluation of multi-user multiple-input multiple-output digital beamforming algorithms in B5G/6G low Earth orbit satellite systems

Satellite communication systems will be a key component of 5G and 6G networks to achieve the goal of providing unlimited and ubiquitous communications and deploying smart and sustainable networks. To meet the ever-increasing demand for higher throughput in 5G and beyond, aggressive frequency reuse schemes (i.e., full frequency reuse), combined with digital beamforming techniques to cope with the massive co-channel interference, are recognized as a key solution. Aimed at (i) eliminating the joint optimization problem among the beamforming vectors of all users, (ii) splitting it into distinct ones, and (iii) finding a closed-form solution, we propose a beamforming algorithm based on maximizing the users' signal-to-leakage-and-noise ratio served by a low Earth orbit satellite. We investigate and assess the performance of several beamforming algorithms, including both those based on channel state information at the transmitter, that is, minimum mean square error and zero forcing, and those only requiring the users' locations, that is, switchable multi-beam. Through a detailed numerical analysis, we provide a thorough comparison of the performance in terms of per-user achievable spectral efficiency of the aforementioned beamforming schemes, and we show that the proposed signal to-leakage-plus-noise ratio beamforming technique is able to outperform both minimum mean square error and multi-beam schemes in the presented satellite communication scenario

Management of encrusted ureteral stents

Objectives: To present our experience in managing encrusted ureteral stents and to review the literature on the subject.Methods: A total of 22 patients with encrusted ureteral stent were treated in our department. Encrustation of the stent and associated stone burden were evaluated using plain radiography, sometimes supplemented by intravenous urography or ultrasonography. The treatment method was determined by the site of encrustation, the size of the stone burden and the availability of endourologic equipment.Results: Stents were inserted for stone disease in 17 patients, for congenital abnormality in 3 and for ureteric obstruction by malignancy in 2. Stents were left in place for a mean of 10.8 months (range 5–34 months). The site of encrustation was in the bladder in 15 (68.2%), ureter in 13 (59%) and kidney in 8 patients (36.4%); more than one site was involved in 11 (50%) cases. For upper coil encrustations, retrograde ureterorenoscopy was performed in 9 cases, percutaneous nephrolithotomy in 4 and open pyelolithotomy in 2. For lower coil encrustation, fragmentation by grasper and/or transurethral cystolithotripsy was attempted in 11 cases, and suprapubic cystolithotomy was required for failure in 7 cases. Sixteen patients (72.7%) were rendered stone-free and 5 (22.7%) had clinically insignificant residual stones (3mm or less).Conclusions: Encrustation is one of the most difficult complications of ureteral stents and its management is a complex clinical scenario for the treating surgeon. The combination of several surgical techniques is often necessary but the best treatment remains the prevention of this problem by providing patient education

Validity of the rheumatoid arthritis MRI score applied to the forefeet using the OMERACT filter: a systematic literature review

Imaging- and therapeutic targets in neoplastic and musculoskeletal inflammatory diseas

Walking disabilities are associated with tenosynovitis at the metatarsophalangeal joints: a longitudinal MRI‐study in early arthritis

Pathophysiology and treatment of rheumatic disease

Zenker's Diverticulum: Can Protocolised Measurements with Barium SWALLOW Predict Severity and Treatment Outcomes? The "Zen-Rad" Study

Although barium swallow imaging is established in the investigation of Zenker's diverticulum (ZD), no agreed measurement protocol exists. We developed a protocol for measuring ZD dimensions and aimed to correlate measurements with symptoms and post-operative outcomes. This prospective study included patients with confirmed ZD who underwent flexible endoscopic septal division (FESD) between 2014 and 2018. ZD was confirmed on barium radiology with measurements reviewed by two consultant radiologists. Symptom severity pre- and post-FESD was measured using the Dysphagia, Regurgitation, Complications (DRC) scale. Regression analyses were conducted to identify dimensions associated with therapeutic success, defined as remission (DRC score ≤ 1) 6 months after index FESD. In total, 67 patients (mean age 74.3) were included. Interobserver reliability (intraclass correlation coefficients-ICCs) was greatest for pouch width (0.981) and pouch depth (0.934), but not oesophageal depth (0.018). Male gender (60.9%) was associated with larger pouch height (P = 0.008) and width (P = 0.004). A positive correlation was identified between baseline DRC score and pouch depth (ρ 0.326, P = 0.011), particularly the regurgitation subset score (ρ 0.330, P = 0.020). The index pouch depth was associated with FESD procedure time (rho 0.358, P = 0.041). Therapeutic success was achieved in 64.2% and was associated with shorter pouch height (median 14.5 mm vs. 19.0 mm, P = 0.030), pouch width (median 19.9 mm vs. 28.8 mm, P = 0.34) and cricopharyngeal length (median 20.2 mm vs. 26.3 mm, P = 0.036). ZD dimensions may be feasible and were evaluated using Barium radiology. Specific parameters appear to correlate with severity and post-FESD outcomes, which aid with pre-procedural planning

Developing institutional capacity for reproductive health in humanitarian settings: A descriptive study

© 2015 Tran et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Introduction. Institutions play a central role in advancing the field of reproductive health in humanitarian settings (RHHS), yet little is known about organizational capacity to deliver RHHS and how this has developed over the past decade. This study aimed to document the current institutional experiences and capacities related to RHHS. Materials and Methods. Descriptive study using an online questionnaire tool. Results. Respondents represented 82 institutions from 48 countries, of which two-thirds originated from low-and middle-income countries. RHHS work was found not to be restricted to humanitarian agencies (25%), but was also embraced by development organizations (25%) and institutions with dual humanitarian and development mandates (50%). Agencies reported working with refugees (81%), internally-displaced (87%) and stateless persons (20%), in camp-based settings (78%), and in urban (83%) and rural settings (78%). Sixtyeight percent of represented institutions indicated having an RHHS-related policy, 79% an accountability mechanism including humanitarian work, and 90% formal partnerships with other institutions. Seventy-three percent reported routinely appointing RH focal points to ensure coordination of RHHS implementation. There was reported progress in RHHSrelated disaster risk reduction (DRR), emergency management and coordination, delivery of the Minimum Initial Services Package (MISP) for RH, comprehensive RH services in post-crisis/recovery situations, gender mainstreaming, and community-based programming. Other reported institutional areas of work included capacity development, program delivery, advocacy/policy work, followed by research and donor activities. Except for abortion-related services, respondents cited improved efforts in advocacy, capacity development and technical support in their institutions for RHHS to address clinical services, including maternal and newborn health, sexual violence prevention and response, HIV prevention, management of sexually-transmitted infections, adolescent RH, and family planning. Approximately half of participants reported that their institutions had experienced an increase in dedicated budget and staff for RHHS, a fifth no change, and 1 in 10 a decrease. The Interagency RH Kits were reportedly the most commonly used supplies to support RHHS implementation. Conclusion. The results suggest overall growth in institutional capacity in RHHS over the past decade, indicating that the field has matured and expanded from crisis response to include RHHS into DRR and other elements of the emergency management cycle. It is critical to consolidate the progress to date, address gaps, and sustain momentum

Reliability of Magnetic Resonance Imaging (MRI) scoring of the metatarsophalangeal joints of the foot according to the Rheumatoid Arthritis MRI Score

Objective. The Rheumatoid Arthritis Magnetic Resonance Imaging Score (RAMRIS) is validated for hand MRI. Its reliability applied to metatarsophalangeal (MTP 1-5) joints is unknown and was studied in early arthritis and clinically suspect arthralgia.Methods. Patients underwent 1.5 Tesla MRI of MTP, metacarpophalangeal (MCP 2-5), and wrist joints. Two paired readers scored bone marrow edema (BME), synovitis, tenosynovitis, and erosions. Interreader reliability was assessed of 441 consecutive early arthritis patients at baseline, 215 by 2 readers, and the remaining 226 by 2 different readers. Two readers scored baseline MRI of 82 consecutive patients with clinically suspect arthralgia, and 40 randomly selected patients by 9 readers. Intrareader reliability was determined on a random set of 15 early arthritis patients, scored twice by 2 readers. For change scores, 30 early arthritis patients with baseline and 1-year followup MRI were scored by 2 readers. Intraclass correlation coefficients (ICC), Bland-Altman (BA) plots, and smallest detectable change (SDC) were determined. MRI data of MTP joints were compared to wrist and MCP joints.Results. Interreader ICC and mean scores in early arthritis were BME ICC 0.91-0.92 (mean 1.5 +/- SD 2.6), synovitis 0.90-0.92 (1.3 +/- 1.7), tenosynovitis 0.80-0.85 (1.1 +/- 1.8), and erosions 0.88-0.89 (0.7 +/- 1.0). In patients with clinically suspect arthralgia, ICC were comparable. Intrareader ICC for inflammatory MRI features were 0.84-0.98, for erosions 0.71 (reader 1), and 0.92 (reader 2). Change score ICC were = 0.90, except erosions (0.77). SDC were = 1.0. BA plots showed no systematic bias. Reliability scores of MTP joints were similar to MCP and wrist joints.Conclusion. Status and change MRI scores of BME, synovitis, tenosynovitis, and erosions of MTP joints can be assessed reliably by RAMRIS.Imaging- and therapeutic targets in neoplastic and musculoskeletal inflammatory diseas

Increased frequency of intermetatarsal and submetatarsal bursitis in early rheumatoid arthritis: a large case-controlled MRI study

Background: The forefoot is a preferential location for joint and tendon sheath inflammation in rheumatoid arthritis (RA). It also contains bursae, of which the intermetatarsal bursae have a synovial lining. Some small imaging studies suggested that intermetatarsal bursitis (IMB) and submetatarsal bursitis (SMB) are involved in RA, but their association has not been thoroughly explored. Healthy control studies suggested that lesion size might be relevant. We studied the relation between IMB and SMB in early RA, compared to other arthritides and healthy controls, and the relevance of lesion sizes. Methods: Six hundred and thirty-four participants were studied: 157 consecutive patients presenting with early RA, 284 other arthritides, and 193 healthy controls. All underwent unilateral contrast-enhanced MRI of the forefoot at presentation. Two readers independently scored IMB and SMB and measured transverse and dorsoplantar diameters, blinded to clinical data. Subsequently, consensus was reached. Intra-reader ICC was 0.89. Logistic regression models were used, and test characteristics were calculated. Results: IMB and SMB associated with RA independent of each other (P < 0.001) and independent of age, gender, BMI, RA-MRI inflammation, and anti-CCP-antibodies (P = 0.041). Sensitivity for RA of IMB was 69%, and for SMB 25%. Specificity for IMB was 70% compared to other arthritides, and 84% compared to healthy controls. For SMB, this was 94% and 97% respectively. Regarding lesion size, the groups had considerable overlap: no cut-off size for RA could be distinguished with high sensitivity and specificity. Conclusion: Intermetatarsal and submetatarsal bursitis associated with early rheumatoid arthritis, contributing to the emerging evidence that inflammation of juxta-articular soft tissues is an early feature of RA