Analysis and Optimization of Dynamic Spectrum Sharing for Cognitive Radio Networks

The goal of this dissertation is to present the analysis and optimization of dynamic spectrum sharing for cognitive radio networks (CRNs). Spectrum scarcity is a well known problem at present. In order to deal with this problem, dynamic spectrum sharing (DSS) was proposed. DSS is a technique where cognitive radio networks dynamically and opportunistically share the channels with primary users. The major contribution of this dissertation is in analyzing the problem of dynamic spectrum sharing under different scenarios and developing optimal solutions for these scenarios. In the first scenario, a contention based dynamic spectrum sharing model is considered and its throughput analysis is presented. One of the applications of this throughput analysis is in finding the optimal number of secondary users in such a scenario. The problem is studied for fixed and random allocation of channels to primary users while secondary users try to opportunistically use these channels. Primary users contend for the channels, and secondary users try to use the channels only when primary users are not using it. These secondary users themselves contend for the opportunistic usage. The numerical formulas developed for finding the optimal number of secondary users have been carefully analyzed with the solutions obtained using the throughput model directly and finding the optimal number of secondary users. These two match very closely with each other and hence provide simple numerical formulas to calculate the optimal number. The second scenario studied is based upon the idea of pre-knowledge of primary user activity. For instance, the active broadcasting periods of TV channels can be obtained from past measurements as the TV channels activities are approximately fixed. In this scenario, time spectrum block (TSB) allocation for DSS is studied. Optimal TSB allocation is considered to minimize the total interference of the system and hence maximize the overall throughput of the system of community networks. The results obtained using the proposed ABCD algorithm follow very closely with the optimal results. Thus the simple algorithm developed can be used for time spectrum block allocation in practical scenarios

A PSO Optimized Model for Identifying Spatio Temporal Hotspots of Terrorist Incidents in India

Terrorism is a global issue that prevails throughout the world on all scales. As the distribution of terrorist activities does not follow a random pattern in space and time, its spatiotemporal analysis has drawn considerable attention in recent years. Further, timely identification of Spatio-temporal terrorist activity hotspots is vital to prioritize the security efforts put by a country’s security enforcement agencies. The state-of-the-art methods for Spatiotemporal hotspot detection are based on scan statistics, which enumerates many Spatio-temporal cylinders, making it a computationally expensive approach. Therefore, this paper presents a time-efficient Particle Swarm Optimizer (PSO) based algorithm to detect the most significant Spatio-temporal hotspots. We formulated an optimization model for the problem and applied three variants of PSO viz. conventional PSO, HCL-PSO, and Ensemble PSO. Finally, these schemes have been used to detect spatio-temporal hotspots of different terrorist attacks in India. The results obtained by PSO-based methods have been compared with SaTScan over two parameters: the time required to detect the hotspot and its quality. All the PSO-based schemes significantly outperformed SaTScan in the timely identification of the hotspots. In addition, the quality of hotspots detected by HCL-PSO is at par with SaTScan, whereas the quality of hotspots detected by the other two approaches is slightly lesser than SaTScan. However, the quality of hotspots detected by the other two variants of PSO is slightly lesser than SaTScan. The results are statistically validated using Friedman’s statistical test

RARE-30. PEDIATRIC GLIOBLASTOMA IN THE POST-TEMOZOLOMIDE ERA: OUTCOMES AND CHARACTERISTICS

Abstract INTRODUCTION Glioblastoma (GBM) is the most common brain tumor, however, is a rare occurrence in children and is poorly characterized. We evaluated the characteristics and outcomes of pediatric GBM (pGBM). METHODS Retrospective analysis of pediatric (age< 18) patients diagnosed with GBM undergoing first glioblastoma resection at our brain tumor center (2005- 2016). RESULTS From 1457 GBM patients, we identified twenty-four (1.65%) pGBMs (Median Age=9 years, Females=45.8%). Median overall survival (OS) was 32.1 months, while the median progression-free survival was 11.5 months. The commonest symptoms at presentation were headaches (54.2%,n=13) and motor symptoms (50%,n=12). Mean tumor diameter was 4.5 cm and 25% of the cohort underwent gross total resection (GTR) of their tumor. Univariate analysis revealed median OS significantly associated with tumor extent of resection (GTR=56.4 months; STR/Biopsy=13.7 months, p=0.001), age at surgery (>10 years=43.9 months, < 10 years= 17.2 months, p=0.01), tumor size (> 4cm= 9.1 months, < 4cm=56.9 months, p=0.01),motor symptoms at presentation (present=14.9 months, absent=41.04 months, p=0.02) and infratentorial tumors (infratentorial=17.4 vs supratentorial=53.4 months, p=0.02). Multivariate analysis revealed GTR (HR 0.2[95% CI 0.07–0.72]; p=0.03), Age >10 years (HR 0.6[95% CI 0.02–0.64]; p=0.002), tumor >4 cm (HR 2.89[95% CI 1.88–4.11]; p=0.001) and EGFR amplification (HR 3.48[95% CI 0.82–17.4]; p=0.005) to be independent predictors of OS. Comparing patients under and over 10 years, we found that older patients had smaller tumors at presentation (4.9 vs 3.6 cms, p=0.03), greater rates of preoperative temozolomide (n=1,7.7% vs n=6, 54.5%) and bevacizumab (n=1,7.7% vs n=4, 36.4%) treatment, and lower rates of EGFR amplification (66.7% vs 11.1%) that could explain survival disparities between groups. CONCLUSION Motor symptoms, larger tumors at presentation and tumor EGFR amplification may be indictive of poorer outcomes in pGBM. However, maximal tumor resection, aggressive chemoradiation and tumor presentation at age >10 years may confer better prognosis in these patients

Longer and better lives for patients with atrial fibrillation:the 9th AFNET/EHRA consensus conference

Aims: Recent trial data demonstrate beneficial effects of active rhythm management in patients with atrial fibrillation (AF) and support the concept that a low arrhythmia burden is associated with a low risk of AF-related complications. The aim of this document is to summarize the key outcomes of the 9th AFNET/EHRA Consensus Conference of the Atrial Fibrillation NETwork (AFNET) and the European Heart Rhythm Association (EHRA). Methods and results: Eighty-three international experts met in Münster for 2 days in September 2023. Key findings are as follows: (i) Active rhythm management should be part of the default initial treatment for all suitable patients with AF. (ii) Patients with device-detected AF have a low burden of AF and a low risk of stroke. Anticoagulation prevents some strokes and also increases major but non-lethal bleeding. (iii) More research is needed to improve stroke risk prediction in patients with AF, especially in those with a low AF burden. Biomolecules, genetics, and imaging can support this. (iv) The presence of AF should trigger systematic workup and comprehensive treatment of concomitant cardiovascular conditions. (v) Machine learning algorithms have been used to improve detection or likely development of AF. Cooperation between clinicians and data scientists is needed to leverage the potential of data science applications for patients with AF. Conclusions: Patients with AF and a low arrhythmia burden have a lower risk of stroke and other cardiovascular events than those with a high arrhythmia burden. Combining active rhythm control, anticoagulation, rate control, and therapy of concomitant cardiovascular conditions can improve the lives of patients with AF

Costs and outcomes of mobile cardiac outpatient telemetry monitoring post-transcatheter aortic valve replacement

Aim: To estimate the costs and outcomes of transcatheter aortic valve replacement (TAVR) recipients based on the use of mobile cardiac outpatient telemetry (MCOT) monitoring. Materials & methods: A retrospective database study was conducted to estimate costs, contribution margins (CMs), pacemaker insertions and other outcomes for patients undergoing TAVR procedures with MCOT monitoring post-procedure versus non-MCOT monitoring. Results: A total of 4164 patients were identified (283 MCOT monitoring and 3881 non-MCOT monitoring). The rate of pacemaker insertion following hospital discharge was higher in the MCOT cohort (6.6 MCOT vs 2.1% non-MCOT; p = 0.007). MCOT use was associated with lower costs and improved CMs of the index TAVR admission (costs: US$40,569 MCOT vs$43,289 non-MCOT; p = 0.003; CMs: US$7087 MCOT vs$5177 non-MCOT; p = 0.047) with no difference through the subsequent 60-day period following discharge. Conclusion: MCOT for ambulatory cardiac monitoring post-TAVR discharge is associated with higher rates of pacemaker insertion, at no overall greater costs

RARE-30. PEDIATRIC GLIOBLASTOMA IN THE POST-TEMOZOLOMIDE ERA: OUTCOMES AND CHARACTERISTICS

Abstract INTRODUCTION Glioblastoma (GBM) is the most common brain tumor, however, is a rare occurrence in children and is poorly characterized. We evaluated the characteristics and outcomes of pediatric GBM (pGBM). METHODS Retrospective analysis of pediatric (age< 18) patients diagnosed with GBM undergoing first glioblastoma resection at our brain tumor center (2005- 2016). RESULTS From 1457 GBM patients, we identified twenty-four (1.65%) pGBMs (Median Age=9 years, Females=45.8%). Median overall survival (OS) was 32.1 months, while the median progression-free survival was 11.5 months. The commonest symptoms at presentation were headaches (54.2%,n=13) and motor symptoms (50%,n=12). Mean tumor diameter was 4.5 cm and 25% of the cohort underwent gross total resection (GTR) of their tumor. Univariate analysis revealed median OS significantly associated with tumor extent of resection (GTR=56.4 months; STR/Biopsy=13.7 months, p=0.001), age at surgery (>10 years=43.9 months, < 10 years= 17.2 months, p=0.01), tumor size (> 4cm= 9.1 months, < 4cm=56.9 months, p=0.01),motor symptoms at presentation (present=14.9 months, absent=41.04 months, p=0.02) and infratentorial tumors (infratentorial=17.4 vs supratentorial=53.4 months, p=0.02). Multivariate analysis revealed GTR (HR 0.2[95% CI 0.07–0.72]; p=0.03), Age >10 years (HR 0.6[95% CI 0.02–0.64]; p=0.002), tumor >4 cm (HR 2.89[95% CI 1.88–4.11]; p=0.001) and EGFR amplification (HR 3.48[95% CI 0.82–17.4]; p=0.005) to be independent predictors of OS. Comparing patients under and over 10 years, we found that older patients had smaller tumors at presentation (4.9 vs 3.6 cms, p=0.03), greater rates of preoperative temozolomide (n=1,7.7% vs n=6, 54.5%) and bevacizumab (n=1,7.7% vs n=4, 36.4%) treatment, and lower rates of EGFR amplification (66.7% vs 11.1%) that could explain survival disparities between groups. CONCLUSION Motor symptoms, larger tumors at presentation and tumor EGFR amplification may be indictive of poorer outcomes in pGBM. However, maximal tumor resection, aggressive chemoradiation and tumor presentation at age >10 years may confer better prognosis in these patients

Laparoscopic Repair of Diaphragmatic Hernias: Experience of Six Cases

Laparoscopic diaphragmatic hernia repair is increasingly performed in adults for congenital diaphragmatic hernias and chronic traumatic diaphragmatic hernias. This study reviewed our experience with laparoscopic diaphragmatic hernia repair to evaluate its safety, efficacy and outcomes. Methods: Between January 1999 and December 2002, four male and two female patients presented to us with diaphragmatic hernias, three with traumatic and three with congenital hernias. The mean age of patients was 58.6 years (range, 42-83 years). Five patients presented with main complaints of postprandial retrosternal/chest discomfort and one patient had an acute gastric outlet obstruction. Dissection was performed laparoscopically to reduce the contents of the sac and the hernial defect was repaired using prolene sutures and a polypropylene mesh. Results: Laparoscopic repair of diaphragmatic hernias was completed successfully in all patients. The mean size of the defect was 6.8 cm (range, 3-12 cm) and the mean operative time was 100 minutes (range, 60-150 minutes). There were no major intraoperative complications. One patient required placement of a chest tube due to inadvertent opening of the pleura with the hernial sac and one patient had prolonged postoperative gastric ileus. The mean hospital stay was 2.3 days (range, 1-4 days) and the mean pain score was 4 (range, 2-6). All patients remained asymptomatic over a mean follow-up of 2.9 years. Conclusion: Adult congenital and chronic traumatic diaphragmatic hernias are amenable to laparoscopic repair. Laparoscopic repair is safe and feasible and confers all the advantages of minimal access surgery

Mobile Cardiac Outpatient Telemetry Patch vs Implantable Loop Recorder in Cryptogenic Stroke Patients in the US – Cost-Minimization Model

Purpose: The aim of this study was to compare costs and outcomes of mobile cardiac outpatient telemetry (MCOT) patch followed by implantable loop recorder (ILR) compared to ILR alone in cryptogenic stroke patients from the US health-care payors’ perspective. Patients and Methods: A quantitative decision tree cost-minimization simulation model was developed. Eligible patients were 18 years of age or older and were diagnosed with having a cryptogenic stroke, without previously documented atrial fibrillation (AF). All patients were assigned first to one then to the alternative monitoring strategies. Following AF detection, patients were initiated on oral anticoagulants (OAC). The model assessed direct costs for one year attributed to MCOT patch followed by ILR or ILR alone using a monitoring duration of 30 days post-cryptogenic stroke. Results: In the base case modeling, the MCOT patch arm detected 4.6 more patients with AFs compared to the ILR alone arm in a cohort of 1000 patients (209 vs 45 patients with detected AFs, respectively). Using MCOT patch followed by ILR in half of the patients initially undiagnosed with AF leads to significant cost savings of US$4,083,214 compared to ILR alone in a cohort of 1000 patients. Cost per patient with detected AF was significantly lower in the MCOT patch arm$29,598 vs $228,507 in the ILR only arm. Conclusion: An initial strategy of 30-day electrocardiogram (ECG) monitoring with MCOT patch in diagnosis of AF in cryptogenic stroke patients realizes significant cost-savings compared to proceeding directly to ILR only. Almost 8 times lower costs were achieved with improved detection rates and reduction of secondary stroke risk due to new antic-oagulant use in subjects with MCOT patch detected AF. These results strengthen emerging recommendations for prolonged ECG monitoring in secondary stroke prevention

Mechanistic Insights into the Pharmacological Significance of Silymarin

Medicinal plants are considered the reservoir of diverse therapeutic agents and have been traditionally employed worldwide to heal various ailments for several decades. Silymarin is a plant-derived mixture of polyphenolic flavonoids originating from the fruits and akenes of Silybum marianum and contains three flavonolignans, silibinins (silybins), silychristin and silydianin, along with taxifolin. Silybins are the major constituents in silymarin with almost 70–80% abundance and are accountable for most of the observed therapeutic activity. Silymarin has also been acknowledged from the ancient period and is utilized in European and Asian systems of traditional medicine for treating various liver disorders. The contemporary literature reveals that silymarin is employed significantly as a neuroprotective, hepatoprotective, cardioprotective, antioxidant, anti-cancer, anti-diabetic, anti-viral, anti-hypertensive, immunomodulator, anti-inflammatory, photoprotective and detoxification agent by targeting various cellular and molecular pathways, including MAPK, mTOR, β-catenin and Akt, different receptors and growth factors, as well as inhibiting numerous enzymes and the gene expression of several apoptotic proteins and inflammatory cytokines. Therefore, the current review aims to recapitulate and update the existing knowledge regarding the pharmacological potential of silymarin as evidenced by vast cellular, animal, and clinical studies, with a particular emphasis on its mechanisms of action

Randomised, siteless study to compare systematic atrial fibrillation screening using enrichment by a risk prediction model with standard care in a Swedish population aged ≥ 65 years: CONSIDERING-AF study design

Introduction Atrial fibrillation (AF) is the most common arrhythmia and confers an increased risk of mortality, stroke, heart failure and cognitive decline. There is growing interest in AF screening; however, the most suitable population and device for AF detection remains to be elucidated. Here, we present the design of the CONSIDERING-AF (deteCtiON and Stroke preventIon by moDEl scRreenING for Atrial Fibrillation) study.Methods and analysis CONSIDERING-AF is a randomised, controlled, siteless, non-blinded diagnostic superiority trial with four parallel groups and a primary endpoint of identifying AF during a 6-month study period set in Region Halland, Sweden. In each group, 740 individuals aged≥65 years will be included. The primary objective is to compare the intervention of AF screening enrichment using a risk prediction model (RPM), followed by 14 days of a continuous ECG patch, with no intervention (standard care). Primary outcome is defined as the incident AF recorded in the Region Halland Information Database after 6 months as compared with standard care. Secondary endpoints include the difference in incident AF between groups enriched or not by the RPM, with and without an invitation to 14 days of continuous ECG recording, and the proportions of oral anticoagulation treatment in the four groups.Ethics and dissemination This study has ethical approval from the Swedish Ethical Review Authority. Results will be published in peer-reviewed international journals.Trial registration number NCT05838781