Analysis of Meandering River Morphodynamics Using Satellite Remote Sensing Data—An Application in the Lower Deduru Oya (River), Sri Lanka

River meandering and anabranching have become major problems in many large rivers that carry significant amounts of sediment worldwide. The morphodynamics of these rivers are complex due to the temporal variation of flows. However, the availability of remote sensing data and geographic information systems (GISs) provides the opportunity to analyze the morphological changes in river systems both quantitatively and qualitatively. The present study investigated the temporal changes in the river morphology of the Deduru Oya (river) in Sri Lanka, which is a meandering river. The study covered a period of 32 years (1989 to 2021), using Landsat satellite data and the QGIS platform. Cloud-free Landsat 5 and Landsat 8 satellite images were extracted and processed to extract the river mask. The centerline of the river was generated using the extracted river mask, with the support of semi-automated digitizing software (WebPlotDigitizer). Freely available QGIS was used to investigate the temporal variation of river migration. The results of the study demonstrated that, over the past three decades, both the bend curvatures and the river migration rates of the meandering bends have generally increased with time. In addition, it was found that a higher number of meandering bends could be observed in the lower (most downstream) and the middle parts of the selected river segment. The current analysis indicates that the Deduru Oya has undergone considerable changes in its curvature and migration rates.publishedVersio

Symptomatology of Coronavirus Disease 2019 (COVID-19):Lessons from A Meta-Analysis Across 13 Countries

Background: COVID-19 pandemic has resulted in varying clinical manifestations and mortality rates. There is no consensus on the symptomatology that would guide researchers and clinicians.Objective: The objective of the study was to identify symptoms and their frequencies of coronavirus disease 2019 with a meta-analysis of studies from several countries. Data sources: A systematic review using PubMed and Google Scholar data sources and reference tracing were used to identify 7176 relevant articles. Eligibility criteria: Suitable articles were selected manually with selection criteria and 14 original articles included for meta-analysis. Data abstraction analysis: PRISMA guideline was used for abstracting data. Then a table was generated by feeding it with numbers and proportions of each symptom described in original studies. A meta-analysis was carried out using random effect models on each symptom separately across the studies and their prevalence rates and 95% confident intervals calculated.Results: We identified 14 relevant scientific papers, either cross-sectional or cohort studies and analyzed. There were 2,660 cases of COVID-19. he majority were from China (n=2,439, 91.7%) and remainder from the Netherlands, Italy, Korea and India and one article from Europe. There was a total of 32 symptoms (i.e. present in >50% of patients): fever (79.56%, 95% CI: 72.17-86.09%), malaise (63.3%, 95% CI: 53.1 – 73.0%), cough (56.7. %, 95% CI: 48.6 - 64.6 %) and cold (55.6%, 95% CI: 45.2 – 65.7%). Symptoms of intermediate incidence (5-49%) were; anosmia, sneezing, ocular pain, fatigue, sputum production, arthralgia, tachypnea, palpitation, headache, chest tightness, shortness of breath, chills, myalgia, sore throat, anorexia, weakness, diarrhea, rhinorrhea, dizziness, nausea, altered level of consciousness, vomiting and abdominal pain. Rare symptoms (<5% of patients) were: tonsil swelling, haemoptysis, conjunctival injection, lymphadenopathy and rash were uncommon symptoms of coronavirus disease (<5%).Conclusion and implications of key findings: We found (25/32) symptoms to be present in =>5% of cases which could be considered as “typical” symptoms of COVID-19. The list of symptoms we identified are different from those documents released by the WHO, CDC, NHS, Chinese CDC, Institute Pasteur and Mayo Clinic. The compiled list would be useful for future researchers to document a comprehensive picture of the illness

A Novel Agarase, Gaa16B, Isolated from the Marine Bacterium <i>Gilvimarinus agarilyticus</i> JEA5, and the Moisturizing Effect of Its Partial Hydrolysis Products

We recently identified a β-agarase, Gaa16B, in the marine bacterium Gilvimarinus agarilyticus JEA5. Gaa16B, belonging to the glycoside hydrolase 16 family of β-agarases, shows less than 70.9% amino acid similarity with previously characterized agarases. Recombinant Gaa16B lacking the carbohydrate-binding region (rGaa16Bc) was overexpressed in Escherichia coli and purified. Activity assays revealed the optimal temperature and pH of rGaa16Bc to be 55 ∘C and pH 6–7, respectively, and the protein was highly stable at 55 ∘C for 90 min. Additionally, rGaa16Bc activity was strongly enhanced (2.3-fold) in the presence of 2.5 mM MnCl2. The Km and Vmax of rGaa16Bc for agarose were 6.4 mg/mL and 953 U/mg, respectively. Thin-layer chromatography analysis revealed that rGaa16Bc can hydrolyze agarose into neoagarotetraose and neoagarobiose. Partial hydrolysis products (PHPs) of rGaa16Bc had an average molecular weight of 88–102 kDa and exhibited > 60% hyaluronidase inhibition activity at a concentration of 1 mg/mL, whereas the completely hydrolyzed product (CHP) showed no hyaluronidase at the same concentration. The biochemical properties of Gaa16B suggest that it could be useful for producing functional neoagaro-oligosaccharides. Additionally, the PHP of rGaa16Bc may be useful in promoting its utilization, which is limited due to the gel strength of agar