STRESS TESTING MQTT SERVER FOR PRIVATE IOT NETWORKS

The rapid development of the Internet of Things (IoT) and the wide area of application rise the IoT concept to be the future of the internet. Indeed, IoT environment has a special nature with a lot of constraints in term of resource consumption. Moreover, the data exchanged between things and the internet is big data. In order to achieve efficiency in IoT communication, many technologies and new protocols based on these technologies have been developed. This paper aims to study the performance of Message Queuing Telemetry Transport (MQTT) by implementing this protocol on test-bed network infrastructure and analyzing the performance properties such as delay jitter, packet loss and throughput for real time and non-real time scenarios. Finally, future research issues in MQTT protocol are suggested

Micro search engine for IoT: an IoT search engine prototype for private networks

Background: The Internet of Things (IoT) has been heralded as the “next big thing” waiting to be realized. IoT revolves around increased machine-to-machine communication and it encompasses various embedded sensorsand actuators that assist users in monitoring and controlling objects remotely in many fields and applications. Methods: IoT's special characteristics introduce challenges in the field of retrieval technology. These challenges constitute of real-time data retrieval with the huge amount of data that can be produced from the sensors. This paper explains the design concepts used to develop a search engine for IoT to tackle these issues. The developed search engine appears to be promising. The performance of the network proved very powerful under normal conditions, however, it could not sustain heavy load under the stress test due to the restricted build of the Z1 motes. Results: The searching capability proved to be quite strong in terms of searching speed and acceptable results; however more tests need to be implemented especially in terms of parallel searching. The GUI is simple and produces multiple features, but lacks interactivity. The security aspect ensures the security of the database with the partial prevention of SQL injection attacks. Conclusion: However, more security measures are required to protect against eavesdropping and unauthentic clients

Seasonality of Respiratory Viral Infections: Will COVID-19 Follow Suit?

Respiratory viruses, including coronaviruses, are known to have a high incidence of infection during winter, especially in temperate regions. Dry and cold conditions during winter are the major drivers for increased respiratory tract infections as they increase virus stability and transmission and weaken the host immune system. The novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) emerged in China in December 2020 and swiftly spread across the globe causing substantial health and economic burdens. Several countries are battling with the second wave of the virus after a devastating first wave of spread, while some are still in the midst of their first wave. It remains unclear whether SARS-CoV-2 will eventually become seasonal or will continue to circulate year-round. In an attempt to address this question, we review the current knowledge regarding the seasonality of respiratory viruses including coronaviruses and the viral and host factors that govern their seasonal pattern. Moreover, we discuss the properties of SARS-CoV-2 and the potential impact of meteorological factors on its spread

Viral metagenomics analysis of stool specimens from children with unresolved gastroenteritis in Qatar

Acute gastroenteritis (AGE) is associated with significant global morbidity and mortality, especially among children under five years of age. Viruses are well established as etiologic agents of gastroenteritis since they are the most common pathogens that contribute to the disease burden in developing countries. Despite the advances in molecular diagnosis, a substantial proportion of AGE etiology remain unresolved. We implemented a viral metagenomics pipeline to determine the potential viral etiology associated with AGE among children under the age of five years in Qatar with undiagnosed etiology. Following enriching for the viral genome, ∼1.3 billion sequences were generated from 89 stool specimens using the Illumina HiSeq platform, of which 7% were mapped to viral genomes. Human viruses were detected in 34 specimens (38.2%); 14 were adenovirus, nine coxsackievirus A16, five rotavirus (G9P[8] and G4P[8]), four norovirus (GII), one influenza A virus (H3), and one respiratory syncytial virus A (RSVA). In conclusion, the viral metagenomics approach is useful for determining AGE's etiology when routine molecular diagnostic assays fail.This study was supported by Qatar National Research Fund (QNRF) funding, grant # NPRP 9–133–1-025, and partial funding from Hamad Medical Corporation, grant # 16173/16

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020

Systèmes d’antennes Ultra-Large-Bande pour Applications In-Band Full-Duplex.

In-band full-duplex technology aims to mitigate the scarcity of spectral resources by allowing two radios to communicate simultaneously in the same frequency band. The main challenge for full-duplex radios is to cancel the self-interference signals, which couple from the transmitter of one radio to its own receiver, by implementing various self-interference cancellation circuity at the antenna, analog, and digital stages of the radio front-end. Conventional selfinterference cancellation techniques were dedicated for narrowband systems and little work has been conducted to extend their performance for wideband operation. Thus, in this work, we focus on studying the wideband potential of the available cancellation techniques and implementing wideband full-duplex systems based on those techniques. The implemented systems are based on the near-field cancellation technique which uses four antennas and two baluns. The systems’ merits vary from extremely wide bandwidth to higher mechanical solidity and dual-polarization, but they all can maintain a decent amount of cancellationLa technologie In-Band Full-Duplex a pour objectif d’augmenter l’efficacité spectrale des liaisons sans-fils en permettant à deux systèmes de communiquer simultanément dans la même bande de fréquence. Dans cette configuration In-Band Full-Duplex, le principal défi consiste à annuler ou réduire les signaux d’auto-interférence, qui se couplent de l’émetteur vers son propre récepteur. Divers circuits d’annulation d’auto- interférence peuvent alors être mis en œuvre : au niveau de l’antenne, de l’étage analogique et/ou numérique. Les techniques classiques d’annulation d’auto-interférence sont majoritairement dédiées aux systèmes à bande étroite et peu de travaux ont été menés pour étendre leurs performances à un fonctionnement en large-bande et encore moins en Ultra-Large-Bande. Dans ce travail, nous nous focalisons sur l’étude des techniques d’annulation compatibles avec un fonctionnement Ultra-Large-Bande et sur leurs mises en œuvre. Les systèmes antennaires proposés sont basés sur une technique d’annulation en champ proche qui utilise quatre antennes et deux baluns. Les avantages des systèmes développés sont multiples, ils proposent tous une bande passante extrêmement large tout en maintenant un niveau d’annulation d’auto-interférence au moins supérieur à 55-60 dB sur cette bande avec des configurations permettant soit d’en augmenter la solidité mécanique, soit d’obtenir unedouble polarisation ou encore avec une alimentation innovante des antennes

Croissance de Nanofils GaAs par HVPE : modélisation, passivation et propriétés de transport

Au-catalyzed growth of GaAs nanowires by HVPE technique has been demonstrated in Institut Pascal many years ago on GaAs substrates. However, the current trend is to integrate these nanowires on silicon substrates, which appears to be very useful for some applications. It is the subject of the present work to develop such process using HVPE which an exceptional length along with very good crystalline quality of nanowires. This manuscript is organized into three chapters. Chapter I is devoted to present the experimental process allowing to obtain such nanowires on Si(111) substrates by Au-catalyzed. It contains also a study of the dewetting of ultra-thin gold films on oxidized Si(111) substrates as function of different parameters, in which we show also by in-situ LEEM and LEED experiments how these droplets remove the SiO2 from the surface and pump silicon atoms from the substrate. The influence of these silicon atoms on the nucleation of GaAs nanowires is presented in chapter II through a thermodynamic model. Another model is also presented in the same chapter in which we study the incorporation of the amphoteric silicon atoms in the solid phase as function of different growth parameters. Chapter III consists in an investigation of charge and spin transport using a polarized µPL experiment on ultra-long GaAs nanowires produced by HVPE. We study the effect of the surface passivation of these nanowires by hydrazine solution and N2-palsma. We report record diffusion lengths for both charge and spin.Alors que la croissance par HVPE de nanofils GaAs est bien maitrisée à l'Institut Pascal sur substrat de GaAs, quant à elle, la croissance sur substrats de silicium reste un sujet à développer. Dans ce travail, nous proposons dans le chapitre I un procédés expérimental permettant d'obtenir des nanofils de GaAs sur substrat de Si(111) par la voie VLS catalysée Au, accompagnés de structures larges appelées écailles. Ce procédé doit être optimiser si un rapport nanofils/écailles plus élevé est souhaité. Nous avons démontré par in-situ LEEM et LEED que les gouttelettes catalyseurs d'Au désoxydent la surface du substrat de Si(111) à haute températures (700 °C) et pompent des atomes de silicium du substrat. L'influence de ces atomes sur la nucléation des nanofils GaAs est étudiée par un modèle thermodynamique présenté dans le chapitre II. Aussi dans le même chapitre, nous présentons une étude de l'incorporation de ces atomes amphotériques de silicium dans le solide GaAs en fonction des paramètres de croissance. Le chapitre III consiste en une investigation du transport de charge et de spin par µPL polarisée dans les nanofils obtenus. Nous avons trouvé des longueurs de diffusion record à basse température dans des nanofils passivés à l'hydrazine et par N2-plasma

Asymmetries Among the Members of Mercosur

The Mercosur countries are very different in terms of their economic size and dimension, their level of development, their population, and the size of their market. Taking into account GDP, population and territory, Uruguay and Paraguay are clearly the smaller Mercosur members and they do not represent even 5% of any of these variables, while Brazil accounts for 70%. At the same time, there are other political and regulatory differences, such as a lack of coordinated macroeconomic policies and incentive policies, in particular. Each member has its own investment promotion policies, as well as policies to support the productive sectors and exports, which alters the conditions for competition between firms even more depending on their country of origin. This combination of structural and politicies asymmetries can be considered an obstacle to deeper integration within Mercosur. This paper addresses considerations on asymmetries and growth, and then moves onto asymmetries and integration and the different ways of addressing and treating this problem in the European Union and in Mercosur. Finally, it considers possible policy impacts.</p

Systèmes d'antennes ultra-large-bande pour applications in-band full-duplex

La technologie in-band full-duplex a pour objectif d’augmenter l'efficacité spectrale des liaisons sans-fils en permettant à deux systèmes de communiquer simultanément dans la même bande de fréquence. Dans cette configuration in-band full-duplex, le principal défi consiste à annuler ou réduire les signaux d’auto-interférence, qui se couplent de l'émetteur vers son propre récepteur. Divers circuits d'annulation d'auto-interférence peuvent alors être mis en oeuvre : au niveau de l’antenne, de l'étage analogique et/ou numérique. Les techniques classiques d'annulation d'auto-interférence sont majoritairement dédiées aux systèmes à bande étroite et peu de travaux ont été menés pour étendre leurs performances à un fonctionnement en large-bande et encore moins en ultra-large-bande. Dans ce travail, nous nous focalisons sur l'étude des techniques d'annulation compatibles avec un fonctionnement ultra-large-bande et sur leurs mises en oeuvre. Les systèmes antennaires proposés sont basés sur une technique d'annulation en champ proche qui utilise quatre antennes et deux baluns. Les avantages des systèmes développés sont multiples, ils proposent tous une bande passante extrêmement large tout en maintenant un niveau d'annulation d'auto-interférence au moins supérieur à 55-60 dB sur cette bande avec des configurations permettant soit d'en augmenter la solidité mécanique, soit d'obtenir une double polarisation ou encore avec une alimentation innovante des antennes.In-band full-duplex technology aims to mitigate the scarcity of spectral resources by allowing two radios to communicate simultaneously in the same frequency band. The main challenge for full-duplex radios is to cancel the self-interference signals, which couple from the transmitter of one radio to its own receiver, by implementing various self-interference cancellation circuitry at the antenna, analog, and digital stages of the radio front-end. Conventional self-interference cancellation techniques were dedicated for narrowband systems and little work has been conducted to extend their performance for wideband operation. Thus, in this work, we focus on studying the wideband potential of the available cancellation techniques and implementing wideband full-duplex systems based on those techniques. The implemented systems are based on the near-field cancellation technique which uses four antennas and two baluns. The systems' merits vary from extremely wide bandwidth to higher mechanical solidity and dual-polarization, but they all can maintain a decent amount of cancellation