The mystery of COVID-19 reinfections: A global systematic review and meta-analysis

Background: As the COVID-19 pandemic rages on, reports on disparities in vaccine roll out alongside COVID-19 reinfection have been emerging. We conducted a systematic review to assess the determinants and disease spectrum of COVID-19 reinfection.Materials and methods: A comprehensive search covering relevant databases was conducted for observational studies reporting Polymerase Chain Reaction (PCR) confirmed infection and reinfection cases. A quality assessment tool developed by the National Institute of Health (NIH) for the assessment of case series was utilized. Meta-analyses were performed using RevMan 5.3 for pooled proportions of findings in first infection and reinfection with a 95% confidence interval (CI).Results: Eighty-one studies reporting 577 cases were included from 22 countries. The mean age of patients was 46.2 ± 18.9 years and 179 (31.0%) cases of comorbidities were reported. The average time duration between first infection and reinfection was 63.6 ± 48.9 days. During first infection and reinfection, fever was the most common symptom (41.4% and 36.4%, respectively) whilst anti-viral therapy was the most common treatment regimen administered (44.5% and 43.0%, respectively). Comparable odds of symptomatic presentation and management were reported for the two infections. However, a higher Intensive Care Unit (ICU) admission rate was observed in reinfection compared to first infection (10 vs 3). Ten deaths were reported with respiratory failure being the most common cause of death (7/10 deaths).Conclusion: Our findings support immunization practices given increased ICU admissions and mortality in reinfections. Our cohort serves as a guide for clinicians and authorities in devising an optimal strategy for controlling the pandemic. (249 words)

Comparison of Policy Realization Strategies for LTE Networks

International audienceEfficient radio resource usage and quality of service (QoS) provision are important criterions in order to choose the right QoS policy for the LTE operators. In our previous work, we have proposed to add a new database named as BSLRC (Base Station Load and Radio Conditions) to optimize the operator policy with regard to the radio efficiency [1]. Some concrete voice capacity estimations were also proposed. In this paper, we extend our earlier work by addressing some novel concerns. As a first step, we start by calculating the signaling load due to the use of BSLRC. Then, for voice services the BSLRC method is compared with the explicit congestion notification (already proposed for LTE systems). Both BSLRC and explicit congestion notification (ECN) share the same objective to optimize the choice of codec rate with regard to radio use efficiency. We also propose some capacity estimates for video services as an extension to our previously proposed voice capacity estimations over LTE systems

LTE Pricing Strategies

International audiencePricing plays an important role to efficiently manage the cellular network resources, maintain user required QoS (Quality of Service) levels and to optimize operator's revenue. In this paper, we analyze some previous pricing schemes proposed for general wireless multimedia systems of WiMAX and adapt these methods within LTE (Long Term Evolution) networks. We also propose a dynamic pricing strategy for LTE. Most of these methods (including ours) are based on users' price categories: Gold (or high), Silver (or medium) and Bronze (or low) categories. The price charged to these users may also vary with the QoS level. We compare these methods considering the LTE network context

Multi-agent Coordination in Ad-hoc Networks based on Coalition Formation

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Multi-agent Coordination in Ad-hoc Networks based on Coalition Formation

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Utilisation des systèmes multi-agents coopératifs pour le partage de spectre dans le contexte de la radio cognitive

Static spectrum allocation is a major problem in recent wireless networks. This scarcity problem is temporary and can be alleviated if the spectrum access is performed dynamically. Cognitive radio (CR) is an important new technology which addresses dynamic spectrum access challenges in detail. These challenges include efficient allocation of spectrum for primary (or licensed) and CR (or secondary) users in order to increase spectrum usage and to avoid user conflicts. Therefore, in this research we are interested in developing novel solutions for dynamic and efficient spectrum access under (1) licensed bands where CR users attempt to use the spec-trum by coexisting with the primary users and (2) unlicensed bands where the CR users try to access the spectrum by avoiding conflicts with their neighbors. In our first proposal, we deploy agents over each primary and CR users which allow them to work cooperatively in order to make spectrum access agreements. The simulation results show that our approach achieves good performance in terms of spectrum access, sustaining lower communication overhead. Our second proposal focuses on unlicensed spectrum access where spectrum can be viewed as an open pool and no user has an exclusive license for spectrum access. Using multi-agent system, the CR users cooperate and they form several coalitions. These types of coalitions can provide a less-conflicted access as the agents mutually agree for spectrum sharing. The important comparisons between analytical and simulation results in terms of blocking probability verify the relevance of our approach in CR contextDans les réseaux sans fil de nos jours, l'allocation de spectre est statique et inefficace. Par conséquent, des alternatives doivent être assurées pour réduire la rareté de spectre. La radio cognitive (RC) offre une approche intéressante pour l allocation dynamique de spectre. Cependant, l'utilisation dynamique du spectre soulève plusieurs défis qui doivent être relevés, notamment l'allocation efficace de spectre pour les utilisateurs primaires (bénéficiant d une licence) et secondaires en augmentant l'utilisation du spectre et en évitant les conflits d accès. L'objectif de cette thèse est de proposer de nouvelles solutions pour l allocation dynamique et efficace de spectre. Dans notre première proposition, nous déployons des agents sur les terminaux des utilisateurs primaires et secondaires qui leur permettent de coopérer et d aboutir à des contrats régissant l'allocation du spectre. Les résultats des simulations montrent que notre approche donne de bonnes performances en maximisant l accès dynamique au spectre tout en minimisant le coût en termes de messages échangés. Notre deuxième solution concerne les bandes sans licence où tous les utilisateurs sont secondaires et coopèrent pour former des coalitions. Ces coalitions permettent de fournir l accès au spectre tout en minimisant les conflits étant donné que les agents se sont mis d'accord sur la manière avec laquelle le spectre sera partagé. Les comparaisons entre les résultats de simulation et ceux obtenus par modélisation mathématique notamment en termes de probabilité de blocage montrent la pertinence de notre approche dans ce contexteTROYES-SCD-UTT (103872102) / SudocSudocFranceF

Multi-agent Coordination in Ad-hoc Networks based on Coalition Formation

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COMAS: A Cooperative Multiagent Architecture for Spectrum Sharing

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