Giant photoinduced reflectivity modulation of nonlocal resonances in silicon metasurfaces

Metasurfaces offer a unique playground to tailor the electromagnetic field at subwavelength scale to control polarization, wavefront, and nonlinear processes. Tunability of the optical response of these structures is challenging due to the nanoscale size of their constitutive elements. A long-sought solution to achieve tunability at the nanoscale is all-optical modulation by exploiting the ultrafast nonlinear response of materials. However, the nonlinear response of materials is inherently very weak, and, therefore, requires optical excitations with large values of fluence. We show that by properly tuning the equilibrium optical response of a nonlocal metasurface, it is possible to achieve sizable variation of the photoinduced out-of-equilibrium optical response on the picosecond timescale employing fluences smaller than 250 μJ / cm2, which is 1 order of magnitude lower than previous studies with comparable reflectivity variations in silicon platforms. Our results pave the way to fast devices with large modulation amplitude.<br/

Assessment of partnership development in cross-border regions’ innovation systems (Latvia-Lithuania-Belarus)

The article is devoted to the research and assessment of the development of the triple partnership between the participants of innovation systems – universities, business, and government in the Latvia-Lithuania-Belarus cross-border region which consists of Latvia’s regions (Latgale region), Lithuania’s regions (Vilnius region, Alytus region, Utena region, Panevezys region, Kaunas region), Belarus’s regions (Vitebsk region, Grodno region, Minsk region, Mogilev region). The lack of attention to the above problems typical of this cross-border region determined the relevance of the research. Innovations are one of the key factors both on the macro-level and on the micro-level that influence the sustainable economic development of the region as well as the innovation potential of the enterprise. The stable development and efficient function of the territorial innovation system is the main condition for this. The study is based on a survey of 620 entrepreneurs from small and medium-sized businesses in the cross-border region

Biodiversity revision of a large arctic region as a basis for its monitoring and protection under conditions of active economic development (Nenetsky Autonomous Okrug, Russia)

In the scope of implementing a UNDP / GEF / Ministry of Nature project, a database and a GIS to consider the biodiversity of the Nenetsky Autonomous Okrug were developed. They include information on 2035 animal and 1640 plant species, belonging to 15 model groups. Data were obtained using publications and unpublished sources, the results of studying collections / herbaria of four institutes of the Russian Academy of Sciences, and data of fieldwork (2015) conducted in three coastal areas of Bolshezemelskaya Tundra. The taxonomic richness of the Nenetsky Autonomous Okrug biota is not lower (even higher in some animal groups) than in other large Arctic regions (e.g. Taymyr and Greenland). Some new vegetation syntaxa have been described. And some phytogeographic boundaries have been established. Several animal taxa have been described for the first time for science. Some of species were neither previously recorded in the Nenetsky Autonomous Okrug nor formerly known from Europe («Siberian» species), nor from Russia. Concerning types of ranges, the proportion of species having predominantly Siberian / East Palaearctic / Siberian-Nearctic ranges varied in different model groups from 0% to 30%. The fraction of arctic (in a wide sense) species ranged from 0% to 29%. We considered the status of the natural environment of the Nenetsky Autonomous Okrug to be satisfactory so far as its destruction is particularly local. We strongly confirm the need to create new Protected Areas. The material obtained during the project processing has been applied to the organisation of sanctuaries in the Khaipudyrskaya Bay and Pakhancheskaya Bay, Barents Sea

Thermal Effect of A Fire on A Steel Beam with Corrugated Wall with Fireproof Mineral-wool Cladding

This paper reports a study into the possibility of applying a simplified approach, recommended by standards for conventional steel beams, to determine the heating temperature under the conditions of a fire in relation to steel I-beams with a corrugated wall. The research is predetermined by the limitation of methods that make it possible to determine the heating temperature of this type of beam in a fire using engineering methods with a small amount of calculations. Technical data on steel beams with cladding have been considered for calculation, the features of heat impact of fire on them have been analyzed, a calculation procedure has been devised, the estimation schemes have been built, and the calculations have been performed. Data on the temperature distribution in the cross-sections of beams with and without cladding were obtained by using a simplified method recommended by standards and the refined method based on a finite-element method. Mathematical models have been constructed for calculations that describe the effect of a standard temperature regime of fire on the distribution of temperature in each minute in the cross-sections of steel beams with and without cladding. The models have been described on the basis of the differential equation of thermal conductivity, boundary conditions of the third kind, which take into consideration convective and radiant heat transfer. It was established that the mineral wool cladding of the beam with a corrugated wall is a reliable fire protection agent. The heating temperature of the beam does not reach a critical value of 500 °C in 60 minutes, which provides the class of this beam with the most stringent requirements for its fire resistance in accordance with the classification in line with the acting norms in Ukraine. The simplified method, recommended by the current standards of the European Union and Ukraine, could be effectively used to analyze the fire resistance of these beams and is the basis of the procedure for the estimated assessment of the fire resistance of these structure

The Role of Acidosis in the Pathogenesis of Severe Forms of COVID-19

COVID-19 has specific characteristics that distinguish this disease from many other infections. We suggest that the pathogenesis of severe forms of COVID-19 can be associated with acidosis. This review article discusses several mechanisms potentially linking the damaging effects of COVID-19 with acidosis and shows the existence of a vicious cycle between the development of hypoxia and acidosis in COVID-19 patients. At the early stages of the disease, inflammation, difficulty in gas exchange in the lungs and thrombosis collectively contribute to the onset of acidosis. In accordance with the Verigo-Bohr effect, a decrease in blood pH leads to a decrease in oxygen saturation, which contributes to the exacerbation of acidosis and results in a deterioration of the patient’s condition. A decrease in pH can also cause conformational changes in the S-protein of the virus and thus lead to a decrease in the affinity and avidity of protective antibodies. Hypoxia and acidosis lead to dysregulation of the immune system and multidirectional pro- and anti-inflammatory reactions, resulting in the development of a “cytokine storm”. In this review, we highlight the potential importance of supporting normal blood pH as an approach to COVID-19 therapy

A raster version of the Circumpolar Arctic Vegetation Map (CAVM)

Land cover maps are the basic data layer required for understanding and modeling ecological patterns and processes. The Circumpolar Arctic Vegetation Map (CAVM), produced in 2003, has been widely used as a base map for studies in the arctic tundra biome. However, the relatively coarse resolution and vector format of the map were not compatible with many other data sets. We present a new version of the CAVM, building on the strengths of the original map, while providing a finer spatial resolution, raster format, and improved mapping. The Raster CAVM uses the legend, extent and projection of the original CAVM. The legend has 16 vegetation types, glacier, saline water, freshwater, and non-arctic land. The Raster CAVM divides the original rock-water-vegetation complex map unit that mapped the Canadian Shield into two map units, distinguishing between areas with lichen- and shrub-dominated vegetation. In contrast to the original hand-drawn CAVM, the new map is based on unsupervised classifications of seventeen geographic/floristic sub-sections of the Arctic, using AVHRR and MODIS data (reflectance and NDVI) and elevation data. The units resulting from the classification were modeled to the CAVM types using a wide variety of ancillary data. The map was reviewed by experts familiar with their particular region, including many of the original authors of the CAVM from Canada, Greenland (Denmark), Iceland, Norway (including Svalbard), Russia, and the U.S. The analysis presented here summarizes the area, geographical distribution, elevation, summer temperatures, and NDVI of the map units. The greater spatial resolution of the Raster CAVM allowed more detailed mapping of water-bodies and mountainous areas. It portrays coastal-inland gradients, and better reflects the heterogeneity of vegetation type distribution than the original CAVM. Accuracy assessment of random 1-km pixels interpreted from 6 Landsat scenes showed an average of 70% accuracy, up from 39% for the original CAVM. The distribution of shrub-dominated types changed the most, with more prostrate shrub tundra mapped in mountainous areas, and less low shrub tundra in lowland areas. This improved mapping is important for quantifying existing and potential changes to land cover, a key environmental indicator for modeling and monitoring ecosystems. The final product is publicly available at www.geobotany.uaf.edu and at Mendeley Data, DOI: 10.17632/c4xj5rv6kv.1