Recently water resources reanalysis (WRR) global streamflow products are emerging from high- resolution global models as a means to provide long and consistent global streamflow products for assessment of global challenge such as climate change. Like any other products, the newly developed global streamflow products have limitations accurately represent the dynamics of local streamflow hydrographs. There is a need to locally evaluate and apply correction factors for better representation and make use of the data. This research focuses on the evaluation and correction of the bias embedded in the global streamflow product (WRR, 0.25°) developed by WaterGAP3 hydrological model in the upper Blue Nile basin part of Ethiopia. Three spatiotemporal dynamical bias correction schemes (temporalspatial variable, temporal-spatial constant and spatial variable) tested in twelve watersheds of the basin. The temporalspatial variable dynamical bias correction scheme significantly improves the streamflow estimation. The Nash-Sutcliffe coefficient (NSCE) improves by 30% and bias decreases by 19% for the twelve streamflow gauging stations applying leave one out cross-validation approach in turn. Therefore, the temporal-spatial variable scheme is applicable and can use as one method for the bias correction to use the global data for local applications in the upper Blue Nile basin.
In arid and semiarid ecosystems, plant interspaces are frequently covered by communities of cyanobacteria, algae, lichens and mosses, known as biocrusts. These crusts often act as runoff sources and are involved in soil stabilization and fertility, as they prevent erosion by water and wind, fix atmospheric C and N and contribute large amounts of C to soil. Their contribution to the C balance as photosynthetically active surfaces in arid and semiarid regions is receiving growing attention. However, very few studies have explicitly evaluated their contribution to organic carbon (OC) lost from runoff and erosion, which is necessary to ascertain the role of biocrusts in the ecosystem C balance. Furthermore, biocrusts are not resilient to physical disturbances, which generally cause the loss of the biocrust and thus, an increase in runoff and erosion, dust emissions, and sediment and nutrient losses. The aim of this study was to find out the influence of biocrusts and their removal on dissolved and sediment organic carbon losses. One-hour extreme rainfall simulations (50 mm h-1) were performed on small plots set up on physical soil crusts and three types of biocrusts, representing a development gradient, and also on plots where these crusts were removed from. Runoff and erosion rates, dissolved organic carbon (DOC) and organic carbon bonded to sediments (SdOC) were measured during the simulated rain. Our results showed different SdOC and DOC for the different biocrusts and also that the presence of biocrusts substantially decreased total organic carbon (TOC) (average 1.80±1.86 g m-2) compared to physical soil crusts (7.83±3.27 g m-2). Within biocrusts, TOC losses decreased as biocrusts developed, and erosion rates were lower. Thus, erosion drove TOC losses while no significant direct relationships were found between TOC losses and runoff. In both physical crusts and biocrusts, DOC and SdOC concentrations were higher during the first minutes after runoff began and decreased over time as nutrient-enriched fine particles were washed away by runoff water. Crust removal caused a strong increase in water erosion and TOC losses. The strongest impacts on TOC losses after crust removal occurred on the lichen plots, due to the increased erosion when they were removed. DOC concentration was higher in biocrust-removed soils than in intact biocrusts, probably because OC is more strongly retained by BSC structures, but easily blown away in soils devoid of them. However, SdOC concentration was higher in intact than removed biocrusts associated with greater OC content in the top crust than in the soil once the crust is scraped off. and Consequently, the loss of biocrusts leads to OC impoverishment of nutrient-limited interplant spaces in arid and semiarid areas and the reduction of soil OC heterogeneity, essential for vegetation productivity and functioning of this type of ecosystems.
Liečiť alebo neliečiť dyslipidémie u seniorov? To je otázka. Je pravdepodobné, že v prítomnosti pokročilej aterosklerózy a cievnych kalcifikácií u starých pacientov bude hypolipemická liečba menej úspešná v primárnej aj sekundárnej prevencii kardiovaskulárnych ochorení. Na druhej strane, v tejto skupine pacientov klesá aj bezpečnosť hypolipemickej liečby. Tieto faktory prispievajú k modifikácii pomeru risk/ benefit farmaceutickej liečby dyslipidémií. Napriek výsledkom niektorých štúdií, ktoré spochybnili asociáciu medzi koncentráciami cholesterolu a kardiovaskulárnym rizikom v starobe, cholesterol zostáva významným, ovplyvniteľným rizikovým faktorom aj u pacientov nad 65 rokov, najmä po zohľadnení ďalších komorbidít. Narastajúce dáta, primárne aj sekundárne, v preventívne orientovaných štúdiách potvrdzujú benefit hypolipemickej liečby u vysokorizikových, starých pacientov. Všetci indikovaní pacienti v tejto vekovej skupine by mali byť liečení podľa najnovších odporúčaní medicíny založenej na dôkazoch., To treat or not to treat dyslipidemias in the eldery? That is the question. It is likely that lipid lowering therapy will be less successful in the primary as well as the secondary prevention of cardiovascular events in the presence of advanced atherosclerosis and artery calcification in older patients. On the other hand, safety of lipid lowering therapy in this patient group becomes more problematic. These factors contribute to the modification of the risk/ benefit ratio of pharmaceutical lipid lowering therapy in this population. Even though the results of several studies challenged the association between cholesterol concentrations and cardiovascular risks in older patients, cholesterol remains an important modifiable risk factor in patients over 65 years of age, especially after adjusting for the presence of co/ morbidities. Growing evidence from studies focusing on primary as well as the secondary prevention confirms the benefit of treating high-risk older patients with lipid lowering drug therapy. Therefore, all patients in this age group for whom such treatment is indicated should be treated in accordance with the most current recommendations of the evidence-based medicine., Marek Pytliak, Viola Vargová, Viola Mechírová, Karim Benhatchi, and Lit.: 19