On Performance of Integrated Satellite HAPS Ground Communication: Aerial IRS Node vs Terrestrial IRS Node

With a motive of ubiquitous connectivity over the globe with enhanced spectral efficiency, intelligent reflecting surfaces (IRS) integrated satellite-terrestrial communications is a topic of research interest in an infrastructure-deficient remote terrains. In line with this vision, this paper entails the performance analysis of satellite-terrestrial networks leveraging both aerial and terrestrial IRS nodes, with the support of high altitude platforms over diverse fading channels including shadowed Rician, Rician, and Nakagami-$m$ fading channels. The merits of IRS in enhancing spectral efficiency is analyzed through closed-form expressions of outage probability and ergodic rate. Further, the average symbol error rate analysis for the higher-order quadrature amplitude modulation (QAM) schemes such as hexagonal QAM, rectangular QAM, cross QAM, and square QAM is performed. Practical constraints like antenna gains, path loss, and link fading are considered to characterize the satellite terrestrial links. Finally, a comparison between the high-altitude platforms based IRS node and terrestrial IRS nodes is performed and various insights are drawn under various fading scenarios and path loss conditions. This paper contribute towards understanding and potential implementation of IRS-integrated satellite-terrestrial networks for efficient and reliable communication

Global warming as a driving factor for cyanobacterial blooms in Lake Karaoun, Lebanon

18 pagesInternational audienceThe Middle East region suffers already from the gradual effects of climate change and will be among the most vulnerable regions in the future. As a result, productivity should undergo losses due to high temperatures, drought, floods and soil degradation which threaten food security of Levantine countries. Since water is the critical factor in the region, even slight changes in air temperature and rainfall patterns will have considerable impact. It has been proven that potential climate change may disrupt, on one hand, most ecosystems through changes in their physicochemical conditions, and on the other hand the species which are living in these ecosystems. Then, the biodiversity can be found challenging. In this study, the effects of climate change on population and phytoplankton communities of Lake Karaoun were investigated since 1992. The climate regime shifts have been shown to alter the lake ecosystem. In the past, Lake Karaoun was characterized by a highly diversified microflora dominated by diatoms and green algae. Recent climatic fluctuations, with culmination in 2008-2011 and temperatures exceeding 40˚C have upset this biodiversity. Blooms of cyanobacteria, specifically Microcystis aeruginosa and Aphanizomenon ovalisporum, have occurred and disturbed both the ecosystem and the functioning of the lake

Effect of Irrigation with Lake Water Containing Cylindrospermopsin Toxin on Seed Germination and Seedlings Growth of Cucumis Sativus and Lycopersicon Esculatum

These morphological changes were associated with alterations in primary xylem as a result of the inhibition of root growth and the reduction of water absorption. In addition, altered metabolism of tomato and cucumber seedling exposed to CYNs was manifested by chlorosis and leaf necrosis following a reduction in the chlorophyll content, photosynthesis inhibition and induction of oxidative stress. Cylindrospermopsin (CYN) phytotoxicity, was investigated on seeds and seedlings of tomato (Lycopersicon esculatum L.) and cucumber (Cucumis sativus L.), after irrigation by water contaminated with this toxin. Our results showed that seed germination was reduced after exposure to higher concentrations of CYN. The cucumber seeds were more resistant than tomato seeds to this toxin. The CYN affected also the growth and productivity of seedlings. A significant reduction in the length of stems, roots (principle and lateral) and the number and size of leaves, appeared on the seedlings exposed to CYNs

A collaborative review of the current concepts and challenges of anastomotic leaks in colorectal surgery

The reduction of the incidence, detection and treatment of anastomotic leakage (AL) continues to challenge the colorectal surgical community. AL is not consistently defined and reported in clinical studies, its occurrence is variably reported and its impact on longterm morbidity and health-care resources has received relatively little attention. Controversy continues regarding the best strategies to reduce the risk. Diagnostic tests lack sensitivity and specificity, resulting in delayed diagnosis and increased morbidity. Intra-operative fluorescence angiography has recently been introduced as a means of real-time assessment of anastomotic perfusion and preliminary evidence suggests that it may reduce the rate of AL. In addition, concepts are emerging about the role of the rectal mucosal microbiome in AL and the possible role of new prophylactic therapies. In January 2016 a meeting of expert colorectal surgeons and pathologists was held in London, UK, to identify the ongoing controversies surrounding AL in colorectal surgery. The outcome of the meeting is presented in the form of research challenges that need to be addressed

Intraperitoneal drain placement and outcomes after elective colorectal surgery: international matched, prospective, cohort study

Despite current guidelines, intraperitoneal drain placement after elective colorectal surgery remains widespread. Drains were not associated with earlier detection of intraperitoneal collections, but were associated with prolonged hospital stay and increased risk of surgical-site infections.Background Many surgeons routinely place intraperitoneal drains after elective colorectal surgery. However, enhanced recovery after surgery guidelines recommend against their routine use owing to a lack of clear clinical benefit. This study aimed to describe international variation in intraperitoneal drain placement and the safety of this practice. Methods COMPASS (COMPlicAted intra-abdominal collectionS after colorectal Surgery) was a prospective, international, cohort study which enrolled consecutive adults undergoing elective colorectal surgery (February to March 2020). The primary outcome was the rate of intraperitoneal drain placement. Secondary outcomes included: rate and time to diagnosis of postoperative intraperitoneal collections; rate of surgical site infections (SSIs); time to discharge; and 30-day major postoperative complications (Clavien-Dindo grade at least III). After propensity score matching, multivariable logistic regression and Cox proportional hazards regression were used to estimate the independent association of the secondary outcomes with drain placement. Results Overall, 1805 patients from 22 countries were included (798 women, 44.2 per cent; median age 67.0 years). The drain insertion rate was 51.9 per cent (937 patients). After matching, drains were not associated with reduced rates (odds ratio (OR) 1.33, 95 per cent c.i. 0.79 to 2.23; P = 0.287) or earlier detection (hazard ratio (HR) 0.87, 0.33 to 2.31; P = 0.780) of collections. Although not associated with worse major postoperative complications (OR 1.09, 0.68 to 1.75; P = 0.709), drains were associated with delayed hospital discharge (HR 0.58, 0.52 to 0.66; P < 0.001) and an increased risk of SSIs (OR 2.47, 1.50 to 4.05; P < 0.001). Conclusion Intraperitoneal drain placement after elective colorectal surgery is not associated with earlier detection of postoperative collections, but prolongs hospital stay and increases SSI risk

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Assessment of The trophic state and Chlorophyll-a concentrations using Landsat OLI in Karaoun reservoir, Lebanon

Fadel, A., Faour G. and Slim K. 2016. Assessment of the trophic state and chlorophyll-a concentrations using Landsat OLI in Karaoun reservoir, Lebanon. Lebanese Science Journal, 17(2): 130-145. Harmful algal blooms have become a worldwide environmental problem. A regular and cost-effective monitoring of these blooms is highly needed by lakes managers. Satellite remote sensing imagery like Landsat Operational Land Imager (OLI) can be used to assess and monitor chlorophyll-a in water bodies over large areas in a cost-effective way. In this study, the accuracy of Landsat OLI to estimate chlorophyll-a was examined. Four field campaigns and cloud free images of Landsat OLI with 30 m resolution (01 May 2013, 21 August 2013, 10 July 2015, and 11 August 2015) were used in this study to determine the accuracy of Landsat OLI in estimating chlorophyll-a in a 12 km2 freshwater body, Karaoun reservoir. After atmospheric correction of these images, reflectance of single and multiple band combinations were compared to field chlorophyll-a data. Results of field campaigns showed that the trophic state of Karaoun reservoir is still eutrophic to hypereutrophic with high nutrient concentration and low phytoplankton biodiversity, dominated by cyanobacteria species, Microcystis aeruginosa and Aphanizomenon ovalisporum. On single band level, the in situ chlorophyll-a measurement correlated best with band 5 (0.85 - 0.88 µm), with R=0.75 and R2=0.57. Highest correlation (R=0.84 and R2=0.72) was obtained using band combination, B2:B4 band ratio multiplied by B5. Results indicated that Landsat OLI can be used effectively to determine chlorophyll-a concentration in lakes and reservoirs. We recommend the application of Landsat OLI as a satisfactory and cost effective method for monitoring chlorophyll-a in other lakes through-out the worl

Mapping Aquatic Cyanobacterial Blooms Using Sentinel-2 Satellite Imagery

Algal blooms are harmful and can hinder the use of water. Remote sensing satellite images can help monitor the spatial–temporal distribution of these blooms. This helps us understand their dynamics and manage them better. In our work, we developed an algorithm using Sentinel-2 images. The validated algorithm showed good accuracy, suggesting the potential use of Sentinel-2 images to monitor algal blooms in other water bodies

Evaluation de la qualité biologique des eaux du Nahr el Jaouz (Liban) : application des méthodes indicielles

Evaluation of the water biological quality of Nahr el Jaouz (Lebanon) : application of the index methods. This study is based on the use of various biological methods determining the water quality of Nahr cl Jaouz. These are : diversity and similarity indices, biotic IB and biological normalized global IBGN indices, and diatom index ID. The results distinguish : i) a section upstream from the village of Tannourine, with a rich and diverse benthic fauna and an oligosaprobic diatomic flora indicating a good biological water quality ; ii) a section downstream of Tannourine corresponding to the discharge of waste water, here the values of the different indices are low, chironomids are abundant., self purification follows in this section improving the biological quality of the water ; iii) the middle and lower courses present a deterioration of water quality essentially due to climatic and hydrologie conditions ; the values of quality indices are low, especially in the lower course of the river.Cette étude est basée sur l'application de diverses méthodes biologiques permettant de déterminer la qualité des eaux du Nahr el Jaouz. Il s'agit d'indices de diversité et de similitude, des deux indices biotique IB et biologique normalisé IBGN. et de l'indice diatomique ID. Les résultats obtenus ont permis de distinguer : i) un tronçon depuis la source jusqu'en amont du village de Tannourine. présentant une faune benthique relativement riche et diversifiée et une flore diatomique oligosaprobe. traduisant une bonne qualité des eaux ; ii) un tronçon en aval de Tannourine correspondant à la zone des rejets des eaux usées où les valeurs des différents indices sont faibles et où on note une abondance des Chironomidés ; une auto-épuration s'ensuit dans cette partie du cours supérieur, améliorant la qualité de l'eau et la diversité spécifique iii) un cours moyen et inférieur présentant une détérioration de la qualité des eaux due essentiellement aux conditions climatiques et hydrologiques ; les valeurs des indices de qualité sont faibles, surtout pour le cours inférieur.Khalaf Gaby, Slim Kamal, Saad Zeinab, Nakhlé Khaled Farès. Evaluation de la qualité biologique des eaux du Nahr el Jaouz (Liban) : application des méthodes indicielles. In: Bulletin mensuel de la Société linnéenne de Lyon, 76ᵉ année, n°9-10, Novembre-décembre 2007. pp. 255-268

The Potential of Different Reflectance-Based Algorithms to Retrieve Phycocyanin Concentration through Remote Sensing: Application in a Hypereutrophic Mediterranean Lake

Cyanobacterial blooms impact aquatic environments and human health. Cyanobacterial biomass is usually estimated using traditional time-consuming and costly field sampling techniques. A remote sensing approach is time and cost efficient and feasible for repetitive monitoring. In this work, we test the potential of various algorithms to retrieve phycocyanin concentration in a Mediterranean lake. Field Spectro radiometric measurements and sampling were performed during 2016 and 2017. The results obtained prove that various ratio models can be used for the estimation of phycocyanin, with the model “R(700)/R(600)” being the best (R2 = 0.716). This research highlights the potential of cyanobacteria mapping using various available satellites