bluuebunny/crossref_metadata_2025 huggingface dataset:
Tuning electrical and thermal conductivities of the two-dimensional electron gas in AlN/GaN heterostructures by piezoelectricity
Authors: Abou-Hamdan L , Hamyeh S , Iskandar A , Tauk R , Brault J , Tabbal M , Adam P-M , Kazan M
Published: November 2020

We investigate the electrical and thermal conductivities of the two-dimensional electron gas (2DEG) confined in the quantum well formed at the heterojunction between a thin GaN layer and an AlN layer strained by an Al
x
Ga1−x
N capping layer in the temperature range from 10 to 360 K. The experimental protocol developed to deduce from calorimetric and Hall-effect measurements at a variable temperature the critical characteristics and transport properties of the confined 2DEG is presented. It is found that, in the measured temperature range (10–360 K), the electrical conductivity of the 2DEG is temperature-independent, due to the predominance of scattering processes by interface defects. However, the thermal conductivity shows a linear temperature dependence, mirroring the specific heat of free electrons. The temperature-independent relaxation time associated with the overall electron scattering means that the values obtained for electrical and thermal conductivities are in excellent agreement with those stipulated by the Weidemann–Franz law. It is also found that for weak strain fields in the AlN layer, both the electrical and thermal conductivities of the two-dimensional interfacial electrons increase exponentially with strain. The importance of 2DEG in AlN/GaN quantum wells lies in the fact that the strong piezoelectricity of AlN allows the transport properties of the 2DEG to be tuned or modulated by a weak electric field even with the high density of lattice mismatch induced defects at the AlN-GaN interface .
A one-step synthesis of ultra-long silver nanowires with ultra-high aspect ratio above 2000 and its application in flexible transparent conductive electrodes
Authors: Zhang Lu , Jiang Fuliang , Wu Bisheng , Lv Chencheng , Wu Minghua
Published: November 2020

Silver nanowires (AgNWs), appear as an extremely promising candidate for the next generation of flexible transparent conductive electrodes (FTCEs). However, the performance of AgNWs-FTCEs was severely limited by the aspect ratio of AgNWs, while it was still a big challenge to fabricate AgNWs with high aspect ratio nowadays. To improve the aspect ratio of AgNWs, bromide ion (Br−), cupric ion (Cu2+) and polyvinylpyrrolidone (PVP, Mw ≈ 1300 000) which are beneficial for the synthesis of high aspect ratio AgNWs, were introduced in this article. The high quality and uniform AgNWs with the average diameter of 77.6 nm and the aspect ratio above 2000 were fabricated via a one-step solvothermal method. The effects of reaction time, molar ratio of AgNO3 to PVP and the concentration of CuBr2 on the aspect ratio of AgNWs were discussed. The mechanism of the synthesis of high aspect ratio AgNWs was explored. After that, the prepared AgNWs were spin-coated on the surface of PET film, the FTCEs based on the ultra-high aspect ratio AgNWs without any post-treatments exhibits relatively high transmittance, low haze and low sheet resistance, and the AgNWs have little effect on the optical performance of pristine PET film. The outstanding performance of the prepared FTCEs indicated that the ultra-high aspect ratio AgNWs are ideal materials in the application of FTCEs, and the method of fabricating AgNWs could provide a direction to the high aspect ratio AgNWs.
Hole-transmission enhancement in 4H-silicon carbide light triggered thyristor for low loss
*
Authors: Xi Wang , Hongbin Pu , Jichao Hu , Qing Liu , Chunlan Chen , Bei Xu
Published: November 2020

In this paper, a 20 kV silicon carbide (SiC) light triggered thyristor (LTT) with n-type blocking base is simulated using Synopsys Sentaurus TCAD. In order to reduce the power dissipation, a method that enhances the hole-transmission through electric field induced by gradual doping profile in the n-buffer layer is proposed. The results indicate that the method enhancing the hole-transmission is effective in reducing the power loss of SiC LTT with n-type blocking base. By changing the doping profile of n-buffer layer from uniform to gradual, both on-state loss and switching loss are efficiently reduced. Compared to the conventional SiC LTT with 2.5 μm thick n-buffer layer, when the doping gradient is 1.0 × 1021 cm−4, the on-state and the switching losses of the hole-transmission enhanced SiC LTT are reduced by 34.7% and 17.9%, respectively.
Ab initio investigation of hydrogen-based high T
c superconductor that is stable under ambient environment
Authors: Zhang Ting
Published: November 2020

We report an ab initio investigation of a hydrogen-based high-T
c superconductor candidate—crystalized C4H4 in the cubic-gauche (cg-C4H4) structure, with the symmetry of space group I213. We find the cg-C4H4 structure to be stable under ambient environment; and the evaluation of the electron-phonon coupling strength indicates that the heavily doped cg-C4H4 can generate superconductivity with a T
c ∼ 72 K. The high frequency vibrational modes of hydrogen atoms are found to play an important role in the total electron-phonon interaction strength, and the reduction of structural symmetry compared with graphene further enhances the electron–phonon coupling of the carbon framework. Our investigation illustrates a BCS route to realizing the hydrogen-based high T
c superconductivity.
Work relation in instantaneous-equilibrium transition of forward and reverse processes
Authors: Albay John A C , Kwon Chulan , Lai Pik-Yin , Jun Yonggun
Published: November 2020

Realizing quasistatic processes in finite times requires additional control parameters to keep the system in instantaneous equilibrium (ieq). However, the finite-rate ieq transition of the reverse process is not just the time-reversal of the ieq forward process due to the odd-parity of controlling parameters. We theoretically show a work relation that the dissipated work of the ieq transition of the forward process is the same as that of the corresponding reverse process. The work relation can be interpreted as a generalization of equilibrium (quasistatic) processes. The work relation and the associated statistics of nonequilibrium work are experimentally confirmed in three different Brownian systems: the time-varying harmonic and non-harmonic potentials and the Brownian harmonic transport, which are manipulated by the optical feedback trap.
Four α correlations in nuclear fragmentation: a game of resonances *
Authors: Huang M. , Bonasera A. , Zhang S. , Zheng H. , Wang D. X. , Wang J. C. , Song N. , Tang X. , Lu L. , Zhang G. , Kohley Z. , Rodrigues M. R. D. , Ma Y. G. , Yennello S. J.
Published: November 2020

Heavy ion collisions near the Fermi energy produce a ‘freezout’ region where fragments appear and later decay, emitting mainly neutrons, protons, alpha particles, and gamma rays. These decay products carry information about the decaying nuclei. Fragmentation events may result in high yields of boson particles, especially alpha particles, and may carry important information about the nuclear Bose Einstein condensate (BEC). We study ‘in medium’ four α correlations and link them to the ‘fission’ of 16O in two 8Be in the ground state or 12C*(Hoyle state)+α. Using novel techniques for the correlation functions, we confirm the resonance of 16O at 15.2 MeV excitation energy, and the possibility of a lower resonance, close to 14.72 MeV. The latter resonance is the result of all α particles having 92 keV relative kinetic energies.
Sea level rise and coastal flooding threaten affordable housing
Authors: Buchanan Maya K , Kulp Scott , Cushing Lara , Morello-Frosch Rachel , Nedwick Todd , Strauss Benjamin
Published: November 2020

The frequency of coastal floods around the United States has risen sharply over the last few decades, and rising seas point to further future acceleration. Residents of low-lying affordable housing, who tend to be low-income persons living in old and poor quality structures, are especially vulnerable. To elucidate the equity implications of sea level rise (SLR), we provide the first nationwide assessment of recent and future risks to affordable housing from SLR and coastal flooding in the United States. By using high-resolution building footprints and probability distributions for both local flood heights and SLR, we identify the coastal states and cities where affordable housing—both subsidized and market-driven—is most at risk of flooding. We provide estimates of both the expected number of affordable housing units exposed to extreme coastal water levels and of how often those units may be at risk of flooding. The number of affordable units exposed in the United States is projected to more than triple by 2050. New Jersey, New York, and Massachusetts have the largest number of units exposed to extreme water levels both in absolute terms and as a share of their affordable housing stock. Some top-ranked cities could experience numerous coastal floods reaching higher than affordable housing sites each year. As the top 20 cities account for 75% of overall exposure, limited, strategic and city-level efforts may be able to address most of the challenge of preserving coastal-area affordable housing stock.
A millennium-long ‘Blue Ring’ chronology from the Spanish Pyrenees reveals severe ephemeral summer cooling after volcanic eruptions
Authors: Piermattei Alma , Crivellaro Alan , Krusic Paul J , Esper Jan , Vítek Petr , Oppenheimer Clive , Felhofer Martin , Gierlinger Notburga , Reinig Frederick , Urban Otmar , Verstege Anne , Lobo Hannah , Büntgen Ulf
Published: November 2020

‘Blue Rings’ (BRs) are distinct wood anatomical anomalies recently discovered in several tree species from different sites. While it is evident that they are associated with a cooling-induced lack of cell wall lignification, BRs have yet to be evaluated systematically in paleoclimate studies. Here, we present a continuous wood anatomical assessment of 31 living and relict pine samples from a high-elevation site in the central Spanish Pyrenees that span the period 1150–2017 CE at annual resolution. While most BR years coincide with cold summer temperatures and many BRs follow large volcanic eruptions, some were formed during overall warm summers. We also see a differential response between eruptions: the Samalas eruption is followed by 80% BRs in 1258, but only a modest signal is evident after the 1815 Tambora eruption, and there are no wood anatomical effects of the Laki eruption in 1783–1784. Apparently linked to a cluster of tropical eruptions in 1695 and 1696 CE, 85% BRs occurred in 1698. This new wood anatomical evidence is corroborated by the record of sulphur deposition in polar ice cores, and corresponds with catastrophic famine and unprecedented mortality in Scotland. The extremely rare occurrence of consecutive BRs in 1345 and 1346 marks the onset and spread of the Black Death, Europe’s most devastating plague pandemic. In their ability to capture severe ephemeral cold spells, as short as several days or weeks, BR chronologies can help to investigate and understand the impacts of volcanism on climate and society.
Trading water: virtual water flows through interstate cereal trade in India
Authors: Harris Francesca , Dalin Carole , Cuevas Soledad , N R Lakshmikantha , Adhya Tapan , Joy Edward J M , Scheelbeek Pauline F D , Kayatz Benjamin , Nicholas Owen , Shankar Bhavani , Dangour Alan D , Green Rosemary
Published: November 2020

Cereals are an important component of the Indian diet, providing 47% of the daily dietary energy intake. Dwindling groundwater reserves in India especially in major cereal-growing regions are an increasing challenge to national food supply. An improved understanding of interstate cereal trade can help to identify potential risks to national food security. Here, we quantify the trade between Indian states of five major cereals and the associated trade in virtual (or embedded) water. To do this, we modelled interstate trade of cereals using Indian government data on supply and demand; calculated virtual water use of domestic cereal production using state- and product-specific water footprints and state-level data on irrigation source; and incorporated virtual water used in the production of internationally-imported cereals using country-specific water footprints. We estimate that 40% (94 million tonnes) of total cereal food supply was traded between Indian states in 2011–12, corresponding to a trade of 54.0 km3 of embedded blue water, and 99.4 km3 of embedded green water. Of the cereals traded within India, 41% were produced in states with over-exploited groundwater reserves (defined according to the Central Ground Water Board) and a further 21% in states with critically depleting groundwater reserves. Our analysis indicates a high dependency of Indian cereal consumption on production in states with stressed groundwater reserves. Substantial changes in agricultural practices and land use may be required to secure future production, trade and availability of cereals in India. Diversifying production systems could increase the resilience of India’s food system.
Reducing transatlantic flight emissions by fuel-optimised routing
Authors: Wells Cathie A , Williams Paul D , Nichols Nancy K , Kalise Dante , Poll Ian
Published: November 2020

After decades of limited situational awareness for aircraft flying in the mid-North Atlantic, full satellite coverage will soon be available. This opens up the possibility of altering flight routes to exploit the wind field fully. By considering flights between New York and London, from 1 December, 2019 to 29 February, 2020, it is shown how changes to current practice could significantly reduce fuel use and, hence, greenhouse gas emissions. When airspeed and altitude are constant, the fuel flow rate per unit time is constant and the route with the minimum journey time uses the least fuel. Optimal control theory is used to find these minimum time routes through wind fields from a global atmospheric re-analysis dataset. The total fuel burn and, hence, the emissions (including CO2) are proportional to the ‘air distance’ (the product of airspeed and flight time). Minimum-time routes are compared with the actual routes flown through the wind fields. Results show that current flight tracks have air distances that are typically several hundred kilometres longer than the fuel-optimised routes. Potential air distance savings range from 0.7% to 7.8% when flying west and from 0.7% to 16.4% when flying east, depending on airspeed and which of the current daily tracks is used. Thus, substantial reductions in fuel consumption are possible in the short term. This is in contrast to the incremental improvements in fuel-efficiency through technological advances, which are high cost, high risk and take many years to implement.
Global mean thermosteric sea level projections by 2100 in CMIP6 climate models
Authors: Jevrejeva Svetlana , Palanisamy Hindumathi , Jackson Luke P
Published: November 2020

Most of the excess energy stored in the climate system is taken up by the oceans leading to thermal expansion and sea level rise. Future sea level projections allow decision-makers to assess coastal risk, develop climate resilient communities and plan vital infrastructure in low-elevation coastal zones. Confidence in these projections depends on the ability of climate models to simulate the various components of future sea level rise. In this study we estimate the contribution from thermal expansion to sea level rise using the simulations of global mean thermosteric sea level (GMTSL) from 15 available models in the Coupled Model Intercomparison Project Phase 6 (CMIP6). We calculate a GMTSL rise of 18.8 cm [12.8–23.6 cm, 90% range] and 26.8 cm [18.6–34.6 cm, 90% range] for the period 2081–2100, relative to 1995–2014 for SSP245 and SSP585 scenarios respectively. In a comparison with a 20 model ensemble from Coupled Model Intercomparison Project Phase 5 (CMIP5), the CMIP6 ensemble mean of future GMTSL (2014–2100) is higher for both scenarios and shows a larger variance. By contrast, for the period 1901–1990, GMTSL from CMIP6 has half the variance of that from CMIP5. Over the period 1940–2005, the rate of CMIP6 ensemble mean of GMTSL rise is 0.2 ± 0.1 mm yr−1, which is less than half of the observed rate (0.5 ± 0.02 mm yr−1). At a multi-decadal timescale, there is an offset of ∼10 cm per century between observed/modelled thermosteric sea level over the historical period and modelled thermosteric sea level over this century for the same rate of change of global temperature. We further discuss the difference in GMTSL sensitivity to the changes in global surface temperature over the historical and future periods.
EPiC: Introducing a database of hybrid environmental flow coefficients for construction materials
Authors: Crawford R H , Stephan A , Prideaux F
Published: November 2020

As worldwide consumption of materials continues to rise, there is growing pressure on material, energy and water resources and an increase in waste production and greenhouse gas emissions. A much more sustainable approach to the procurement of built assets is crucial to avoid exacerbating existing environmental pressures. Product and process-based environmental data is an important element in understanding how current and future built assets perform. This paper analyses environmental flow data for a range of construction materials contained within the Environmental Performance in Construction (EPiC) Database, a new, open access repository of hybrid environmental flow coefficients for construction materials. The structural paths of 131 construction materials are analysed to identify trends and contributors to embodied water, energy and greenhouse gas (GHG) emissions coefficients. The disaggregation and analysis of material coefficients shows the complexity of the material supply chains and provides insight into the key inputs and outputs resulting from the production of construction materials.
Current trends of climatically driven minimal heat demand for residential buildings
Authors: Alexandrov G G , Ginzburg A S
Published: November 2020

Heating-related energy consumption depends on climatic conditions and is prone to changes in warming climate. Shortening of heating season is one of the expected effects of climate change. Since the further development and modernization of energy and heat supply systems is influenced by expectations of the climate change, studying the regional climate trends is certainly important. In this article, the authors analyzed historical changes in minimal heating-related energy demand from several Russian and European cities and show that global expectations may do not meet reality at some locations.
Biometeorological characteristics as energy consumption estimates in large Russian cities
Authors: Belova I N , Dokukin S A , Krivenok L A
Published: November 2020

We have conducted a comparative analysis of the climatic and biometeorological characteristics of the regions with the largest Russian cities and have laid the basis for constructing maps of the heating season climatic characteristics for the territory of Russia. For the effective ambient temperature range of 17.2 to 21.7°C (comfort zone), we have calculated changes in the comfort zone for Moscow, St. Petersburg, Krasnodar, Novosibirsk, and Vladivostok according to data from 1959 to the present. Despite all climate differences between regions with selected cities, allowance for wind speed leads to a decrease in the number of days with temperature within the comfort zone.
Vertical profile of saltating particle concentration over semidesert area
Authors: Gorchakov G I , Buntov D V , Karpov A V , Kopeikin V M , Mirsaitov S F , Gushchin R A , Datsenko O I
Published: November 2020

According to measurement data on the desertified area in the Astrakhan oblast in the conditions of non-intermittent saltation, a strong influence of convective quasiperiodic structures with periods from 1.5 to 8 minutes on variations of the saltating particle concentrations are found. Statistical characteristics of the saltating particle concentrations variations are received. The vertical profile of the average particle concentration in the height range from 3 to 15 cm is obtained. An exponential approximation of the particle concentration profile with a logarithmic gradient of -0.32 cm−1 is proposed. It is shown that the average particle content in the saltation layer is 8.6 cm−2.
Physical and chemical properties of atmospheric aerosols in Moscow and its suburb for climate assessments
Authors: Gubanova D P , Elansky N F , Skorokhod A I , Kuderina T M , Iordansky M A , Sadovskaya N V , Anikin P P
Published: November 2020

The paper presents results of experimental study of the physicochemical properties of surface aerosols in the Moscow region in the summer of 2019. Microphysical parameters, mass concentration and elemental composition of submicron and micron aerosol particles are considered, and their morphological structure is described. The features of variability of aerosol characteristics under atypical weather conditions prevailing in June-July 2019 are shown. The spatial distribution of the elemental composition of aerosols is established, a significant degree of their enrichment with heavy metals and metalloids is revealed. Geochemical analysis of aerosols and soils in Moscow was performed, and the coefficients of local aerosol concentration were calculated. The obtained experimental data will be useful for the refinement and verification of climate models.
Theoretical studies of atmospheric perturbations caused by the gravity field inhomogeneities
Authors: Kh Ingel L , Makosko A A
Published: November 2020

In solving atmospheric dynamics problems, the influence of the gravity field inhomogeneities (GFI) is neglected. The traditional basis for this is that the amplitude of gravity variations even in highly anomalous regions do not exceed 10−3 ms−2 in order of magnitude, i.e. 4 orders of magnitude less than average gravity. But in the presence of gravity anomalies, inhomogeneous forces of the same order act in the directions tangent to the mean Earth ellipsoid. The atmosphere dynamics is very sensitive to the forces of such directions. In highly anomalous regions, they are comparable with the main horizontal forces acting in the atmosphere, in particular with the forces of the pressure gradient and Coriolis forces. Therefore, it seems appropriate to analyze the possible effect of spatial variations of gravity on the dynamics of the atmosphere, primarily for mesoscale atmospheric disturbances. In a number of the authors’ previous works, theoretical studies of the possible effect of GFI on the atmosphere dynamics are carried out. This report contains some new relevant findings. A three-dimensional analytical model of geostrophic wind disturbances under the influence of GFI is developed. An analogy of atmospheric disturbances caused by thermal inhomogeneities of the underlying surface and GFI is shown. Attention is drawn to the possibility of “accumulation” of atmospheric effects associated with the gravitational field inhomogeneities.
Vertical helicity flux as an index of interannual atmospheric variability
Authors: Kurgansky M V , Maksimenkov L O , Chkhetiani O G
Published: November 2020

As an index of interannual climatic variability of the atmosphere, it is proposed to calculate the weighted average over the hemisphere area (to the pole from latitude 20°) of the vertical helicity flux across the upper boundary of the planetary boundary layer, which is determined by the product of the Coriolis parameter and the square of the wind speed at this boundary. In practical calculations, the data of reanalyses ERA-Interim and ERA-20C on the wind speed at the isobaric level of 850 hPa were used. The statistical distribution of the Earth’s surface area on the helicity flux values, as well as the informational entropy of this distribution, are calculated. It is shown that the introduced index usefully characterizes the interannual climate variability of the atmosphere in both hemispheres.
Urban Heat Island in Moscow at different heights, depths and on the surface
Authors: Lokoshchenko M A , Korneva I A , Enukova Ye A
Published: November 2020

The urban heat island (UHI) in Moscow was for the first time studied not only at the ground air level, but also at different heights, depths and on the surface using stationary, radiosonde and satellite data. Long-term dynamics of the UHI intensity in the ground air layer has been estimated since the end of the 19th century both as traditional ‘maximal intensity’ (the difference between the city centre and rural zone), and as ‘average intensity’ (the difference between all urban and all rural stations). In recent years they have been 2.0 and 1.0 ºC, respectively. The quasi-stabilization of both parameters in the second half of the 20th century was probably the result of extensive city growth at that time; the new increase in the UHI intensity seems to be connected with the densification of urban development and heat sources in the last 20 years. The mean daily vertical extension of the UHI in the atmosphere is approximately 300 m. In the upper soil layer (up to 160 cm deep) the maximal UHI intensity was about 1.6-1.7 ºC half a century ago. The average UHI intensity at the field of the surface temperature in recent years is 2.7 ºC.
Diagnostics of the La Niña events in 1900–2018
Authors: Marchukova O V , Voskresenskaya E N , Lubkov A S
Published: November 2020

Diagnostics of La-Nina events from 1900 to 2018 is done in this paper using COBE SST2 data sets. Two La Niña space-time types were selected on the basis of two methods. The first of them is empirical orthogonal functions method. The second one is hierarchical cluster analysis. Both of methods showed the absolute identity two selected types. Analyzing the spatiotemporal series of the sea surface temperature anomalies (SSTA) in the equatorial Pacific two main EOFs were obtained. The first EOF mode describes ∼46% of the total dispersion SSTA variability in the equatorial Pacific and demonstrated two consecutive La Niña events that arise after the strong canonical El Niño. The second mode accounts for ∼ 21% of the total dispersion SSTA variability and shows a nature of the East Pacific La Niña occurrence.
Global and regional climate anomalies and trends: Assessment of contribution of natural and anthropogenic factors from observations and model simulations
Authors: Mokhov I I
Published: November 2020

Trends in current global and regional climate change are estimated based on observations and reanalysis data, as well as on the basis of model simulations. Special attention is paid to climate changes in the Arctic and North Eurasian regions. Temperature and sea ice changes in the Arctic and Antarctic are compared. The processes contributing to the enhancement of regional climate variability are considered. The role of natural and anthropogenic factors in climate change and the ability of models to adequately simulate current climate changes are assessed. Possible changes in relative contribution of natural and anthropogenic CO2 and CH4 emissions in the North Eurasian regions under global warming are discussed.
Regional features of intraseasonal temperature variability in the regions of Northern Eurasia with global climate change
Authors: Parfenova M R , Mokhov I I
Published: November 2020

Polymodal (bimodal) features of the probability density functions (PDFs) for long term series of surface air temperature anomalies in transitional (fall, spring) seasons are studied based on daily data from meteorological observations in various North Eurasian regions using a stochastic energy balance model. The observed PDFs are characterized by bimodality with the minimums laying near 0° C. Changes of weather regimes since the middle of 20th century until recent years are analyzed. The increase in probability of negative temperatures for both transitional seasons in the 21st century compared to the 20th century can be linked to global changes in atmosphere circulation patterns and, particularly, to intensification of cold air outbreaks occurrence in spring seasons. “Indian summer” (the effect of recurrent warming in fall seasons) phenomenon is stronger in the 20th century PDF, while the bimodality of PDF around 0° C can signify the nonlinear dependence of albedo on SAT.
Variations and tendencies of cloud, aerosol and solar radiation in the past decades over East of the Asian Part of Russia based on surface and satellite data records
Authors: Plakhina I N , Repina I A
Published: November 2020

The results of studies of atmospheric aerosol over the territory of Russia are of great interest from the point of view of environmental and climatic problems. The article presents the results of the spatial-temporal variability of aerosol optical thickness (AOT) over the Asian Part (AP) of the Russian Federation in recent decades. The Database (DB) “Aerosol optical thickness of the atmosphere from satellite and ground-based observations” created by the authors was used. The presented trends in AOT changes (annual values, summer values) and statistical estimates of real empirical series show that there is a good agreement between the annual values of AOT for satellite and ground-based values, for monthly values the discrepancy has more value. Based on observational and reanalysis data, the interannual variability of the average annual and average summer values of the total radiation flux coming to the surface was studied. The empirical typification of interannual changes in the intra-annual course of the cloud cover values (%) over the considered time interval was carried out. The analysis was performed for the Tiksi Arctic station and for the Yakutsk, Ussuriysk, Irkutsk and Yekaterinburg stations located in the AP of the Russian Federation.
Recent changes of atmospheric composition in background and urban Eurasian regions in XXI-th century
Authors: Rakitin V S , Skorokhod A I , Pankratova N V , Shtabkin Yu A , Rakitina A V , Wang G , Vasilieva A V , Makarova M V , Wang P
Published: November 2020

An analysis of the CO and CH4 total column (TC) as well as aerosol optical depth (AOD) data in background and urban Eurasian regions for different time-periods and seasons from 1998 to 2018 years is presented. Trend estimates based on long-term spectroscopic datasets of OIAP RAS for Moscow, Zvenigorod (ZSS, Moscow province), Beijing (joint site of OIAP RAS and IAP CAS) and NDACC stations located in Eurasia are compared between themselves and with similar assessments obtained from satellite data. The comparison of satellite and ground-based trend estimates was provided for the days of synchronous measurements only. Analysis results of the satellite observations of AIRS v6 of CO and CH4 TC and MODIS AOD data are confirmed by ground-based trend estimates. Significant decrease of anthropogenic CO in the megacities Moscow (2.9±0.6%/yr) and Beijing (1.2±0.2%/yr) for autumn months of 1998-2018 was found according to ground-based spectroscopic observations. In spite of total anthropogenic CO emission decrease (for Europe and China) and the decrease of wild-fires emissions in Central North Eurasia (0-90° E, 42-75° N) in 2008-2018 we found CO TC stabilization or even increasing for summer and autumn months of 2008-2018 in background regions of Northern Eurasia. Decrease of AOD over Central and Southern Europe as well as over China (1-5%/yr) was observed since 2007. Since 2007-2008 an increase in CH4 TC positive trend values over Northern Europe as well as for tropical belt of Eurasia was obtained.
Parameterization of turbulent exchange in the polar regions
Authors: Repina I A , Artamonov A A , Debolskiy A V , Pashkin A D
Published: November 2020

Sea ice plays a significant role in the Earth’s climate system. Significant changes are currently taking place in the sea ice cover area. The structure of sea ice also is changed. Based on field measurements, the paper shows the importance of taking into account the morphometric (structural) inhomogeneities of sea ice for modeling its interaction with the atmosphere. The dependence of the drag coefficient and the aerodynamic parameter of roughness on the surface structure is considered. The drag coefficient nonlinearly depends on the ice concentration, the relative area of the puddles, on the width and configuration of the leads, on the spatial location and height of the hummocks, as well as on the atmospheric stability. The parameterizations proposed in the paper can be used to calculate fluxes in weather and climate models.
Estimation of urban contribution into variability of the aerosol characteristics in the near-ground atmospheric layer in Tomsk region
Authors: Terpugova S A , Kozlov V S , Yausheva E P , Chernov D G , Polkin V V , Shmargunov V P
Published: November 2020

The paper presents the results of monitoring the aerosol characteristics in the near-ground layer of the atmosphere at the Aerosol Station of the Institute of Atmospheric Optics of the Siberian Branch of the Russian Academy of Sciences (IOA SB RAS) located at the southeastern outskirts of city of Tomsk and in the background forest area (the Fonovaya Observatory, ∼ 70 km to southwest from Tomsk) in 2014 – 2018. The data were considered on the concentration of aerosol and absorbing substance (soot, black carbon) at two measurement points, as well as the hygroscopic properties of aerosol particles. The features of the annual behavior and interannual variability of the anthropogenic contribution of the city to the average values of aerosol characteristics are analyzed. A significant trend by 7% per year was revealed for an increase in the soot fraction of aerosol under urban conditions. The typical diurnal behavior of the aerosol and soot concentrations at the Aerosol station is characterized by an increase in these parameters at 21-23 hours local time compared to daytime hours. Also a significant decrease in the aerosol hygroscopicity is observed in evening under urban conditions.
Performance analysis of L-PPM modulated NLOS-VLC system with perfect and imperfect CSI
Authors: Dixit Vipul , Kumar Atul
Published: November 2020

Visible light communication (VLC) has evolved in the last few years as an alternative to radio frequency communication technology. In this paper, the performance analysis of pulse position modulated (PPM) VLC system is presented over non-line of sight (NLOS) channel. Specifically, an L-PPM modulated VLC system is considered in which the communication occurs through single-order reflected components as there is no existence of line of sight (LOS) link between transmitter and receiver. The reflection points on the walls of the room are randomly distributed. The Gaussian approximation is used to derive the bit-error-rate (BER) of the proposed VLC system with perfect and imperfect channel state information available at the receiver. For the given transmitting power, L-PPM modulated NLOS-VLC system, (L > 2), improves the system BER significantly than that of on-off keying modulated NLOS-VLC system. The error performance of the L-PPM modulated NLOS-VLC system is also compared with that of L-PPM modulated LOS-VLC system. For the parameters of interest, the error performance of L-PPM modulated NLOS-VLC system is observed.
A perspective on musical representations of folded protein nanostructures
Authors: Franjou Sebastian L , Milazzo Mario , Yu Chi-Hua , Buehler Markus J
Published: November 2020

Proteins are the building blocks of all life, creating materials as diverse as spider silk, cells, and hair, but also other countless functions from enzymes to drugs. Here we discuss a method to represent folded protein nanostructures as musical compositions. We explore different avenues of artistic creation, interpolating between human design, natural or evolutionary design, and designs from a deep recurrent network model that was trained against musical scores of known three-dimensional protein structures. Artistically, our work offers a new perspective on the limits of scientific understanding, and allows human players to interact with nanoscale phenomena, providing a tool for STEM outreach, and use of nanoscopic phenomena for artistic expression.
The Effects of Aesthetic Lasers on Three Study Materials Used for Ocular Protection
Authors: Wamsley Christine E , Hoopman John E , Kenkel Jeffrey M
Published: November 2020

Background

It is dangerous, although not uncommon, in some clinical settings for laser operators to place gauze underneath external patient protective eyewear when performing laser procedures.

Objectives

The purpose of this study was to evaluate 4 lasers, commonly used for aesthetic facial procedures, on 3 materials commonly found in the clinical setting.

Methods

We performed tests with 4 lasers: the 2940-nm erbium-doped yttrium aluminum garnet (Er:YAG) laser, the 532-nm potassium titanyl phosphate (KTP) laser, the 1064-nm neodymium-doped yttrium aluminum garnet (Nd:YAG) laser, and a Lumenis UltraPulse 10,600-nm carbon dioxide (CO2) laser. Their effects were evaluated on dry gauze pads, wet gauze pads, and adhesive external eye shields.

Results

When exposed to the 2940-nm Er:YAG and 10,600-nm CO2 lasers, dry gauze smoked on the first pulse and ignited on the second pulse, whereas no damage occurred to the wet gauze or adhesive eye shields after 8 and 4 pulses, respectively. No damage to any material or the underlying surface was seen after 30 pulses of the 532-nm KTP laser. After 2 pulses of the 1064-nm Nd:YAG laser, the adhesive eye shields sparked; dry gauze smoked after 1 pulse, but no damage to the underlying surface occurred after 30 pulses.

Conclusions

The results of our study highlight the inherent flammability of gauze when exposed to lasers commonly used to address aesthetic facial concerns. Although moistened gauze conveyed more protection than dry gauze, these results do not guarantee patient ocular safety. Therefore, we do not recommend the use of any gauze under protective eyewear.
Treefrogs adjust their acoustic signals in response to harmonics structure of intruder calls
Authors: Foratto Roseli Maria , Llusia Diego , Toledo Luís Felipe , Forti Lucas Rodriguez
Published: November 2020

Spectral properties of animal acoustic signals may help individuals to assess the characteristics of rivals and to adjust their competitive strategies in territorial disputes. Thus, we hypothesized that the distribution of energy across frequency bands in anuran calls determines behavioral responses in male–male competition. Using playback experiments, we investigated the relevance of the harmonic calls in the acoustic communication of the treefrog Dendropsophus minutus. We exposed territorial males to three synthetic acoustic stimuli composed of aggressive notes: 1) standard call (all harmonics and peak frequency corresponding to the second band); 2) inverted-energy call (all harmonics and peak frequency corresponding to the first band); and 3) concentrated-energy call (all energy contained in the second harmonic). Males responded aggressively to all stimuli, mainly by increasing the rate and duration of their aggressive notes. However, when exposed to stimuli with different harmonic configurations, males changed the harmonic structure of their own calls, emitting more A- and B-notes with peak power in the fundamental frequency, particularly when exposed to the concentrated-energy call. Our results suggest that male frogs may use the harmonic structure of calls to assess opponents and modulate territorial and aggressive behavior, triggering complex acoustic adjustments. This study contributes to our knowledge about the functions of acoustic traits in amphibian social interactions, and particularly of the presence of harmonics that has received less attention compared to other acoustic properties in the study of animal acoustic communication.
Exploration of natural compounds with anti-SARS-CoV-2 activityviainhibition of SARS-CoV-2 Mpro
Authors: Bharadwaj Shiv , Dubey Amit , Yadava Umesh , Mishra Sarad Kumar , Kang Sang Gu , Dwivedi Vivek Dhar
Published: November 2020

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a dreaded pandemic in lack of specific therapeutic agent. SARS-CoV-2 Mpro, an essential factor in viral pathogenesis, is recognized as a prospective therapeutic target in drug discovery against SARS-CoV-2. To tackle this pandemic, Food and Drug Administration-approved drugs are being screened against SARS-CoV-2 Mpro via in silico and in vitro methods to detect the best conceivable drug candidates. However, identification of natural compounds with anti-SARS-CoV-2 Mpro potential have been recommended as rapid and effective alternative for anti-SARS-CoV-2 therapeutic development. Thereof, a total of 653 natural compounds were identified against SARS-CoV-2 Mpro from NP-lib database at MTi-OpenScreen webserver using virtual screening approach. Subsequently, top four potential compounds, i.e. 2,3-Dihydroamentoflavone (ZINC000043552589), Podocarpusflavon-B (ZINC000003594862), Rutin (ZINC000003947429) and Quercimeritrin 6”-O-L-arabinopyranoside (ZINC000070691536), and co-crystallized N3 inhibitor as reference ligand were considered for stringent molecular docking after geometry optimization by DFT method. Each compound exhibited substantial docking energy >−12 kcal/mol and molecular contacts with essential residues, including catalytic dyad (His41 and Cys145) and substrate binding residues, in the active pocket of SARS-CoV-2 Mpro against N3 inhibitor. The screened compounds were further scrutinized via absorption, distribution, metabolism, and excretion - toxicity (ADMET), quantum chemical calculations, combinatorial molecular simulations and hybrid QM/MM approaches. Convincingly, collected results support the potent compounds for druglikeness and strong binding affinity with the catalytic pocket of SARS-CoV-2 Mpro. Hence, selected compounds are advocated as potential inhibitors of SARS-CoV-2 Mpro and can be utilized in drug development against SARS-CoV-2 infection.
OGG1 protects mouse spermatogonial stem cells from reactive oxygen species in culture†
Authors: Mori Yoshifumi , Ogonuki Narumi , Hasegawa Ayumi , Kanatsu-Shinohara Mito , Ogura Atsuo , Wang Yufeng , McCarrey John R , Shinohara Takashi
Published: November 2020

Although reactive oxygen species (ROS) are required for spermatogonial stem cell (SSC) self-renewal, they induce DNA damage and are harmful to SSCs. However, little is known about how SSCs protect their genome during self-renewal. Here, we report that Ogg1 is essential for SSC protection against ROS. While cultured SSCs exhibited homologous recombination-based DNA double-strand break repair at levels comparable with those in pluripotent stem cells, they were significantly more resistant to hydrogen peroxide than pluripotent stem cells or mouse embryonic fibroblasts, suggesting that they exhibit high levels of base excision repair (BER) activity. Consistent with this observation, cultured SSCs showed significantly lower levels of point mutations than somatic cells, and showed strong expression of BER-related genes. Functional screening revealed that Ogg1 depletion significantly impairs survival of cultured SSCs upon hydrogen peroxide exposure. Thus, our results suggest increased expression of BER-related genes, including Ogg1, protects SSCs from ROS-induced damage.
Admissible estimators of a multivariate normal mean vector when the scale is unknown
Authors: Maruyama Y , Strawderman W E
Published: November 2020

We study admissibility of a subclass of generalized Bayes estimators of a multivariate normal vector in the case where the variance is unknown, under scaled quadratic loss. Minimaxity is established for some of these estimators.
Concomitant transcatheter closure of post-myocardial infarction ventricular septal defect and inferior wall aneurysm: case report
Authors: Abuelatta Reda , Alrashidy Tarek , Taha Fatma , Naeim Hesham Abdo
Published: November 2020

Background

The incidence of the post-infarct ventricular septal defect (VSD) is 0.17%. Surgical repair is the definitive treatment and percutaneous closure is an alternative in high-risk patients. We report a case of post-myocardial infarction inferior wall aneurysm associated with a large ventricular septal rupture, with a communication between the aneurysm and right ventricle. Successful percutaneous closure of both the aneurysm and the post-infarct (VSD) was performed using two Amplatzer septal occluder devices.

Case summary

A 76-year-old man was referred to the clinic 2 weeks after an inferior wall myocardial infarction. A harsh, pansystolic murmur was appreciated on his left parasternal area and across the pericardium. An echocardiogram demonstrated a large, true aneurysm in the mid-cavity inferior wall. The inferior septum was ruptured and dissected, with a large, left-to-right shunt. The patient’s coronary angiography revealed a multi-vessel disease. The patient was considered as high surgical risk and thus transcatheter closure of both the post-infarct VSD and inferior wall aneurysm was recommended. We crossed the VSD from the venous side. An Amplatzer septal occluder (18 mm) was deployed to close the VSD completely. We crossed the aneurysm mouth from the arterial side. Another Amplatzer septal occluder (26 mm) was deployed with the large disc inside the aneurysm, sealing it with no more flow. After discharge from the intensive care unit, the patient underwent complete revascularization for his right coronary artery, left main artery, proximal left anterior descending artery, and ramus intermedius. At his 3-month follow-up, the patient remained well with reasonable exercise tolerance.

Discussion

Percutaneous closure of a post-infarct VSD and aneurysm is an option for patients whose comorbidities preclude surgical repair and whose septal anatomy is favourable to device placement.
Low-density lipoprotein cholesterol reduction and statin intensity in myocardial infarction patients and major adverse outcomes: a Swedish nationwide cohort study
Authors: Schubert Jessica , Lindahl Bertil , Melhus Håkan , Renlund Henrik , Leosdottir Margrét , Yari Ali , Ueda Peter , James Stefan , Reading Stephanie R , Dluzniewski Paul J , Hamer Andrew W , Jernberg Tomas , Hagström Emil
Published: November 2020

Aims 

Clinical trials have demonstrated that a reduction in low-density lipoprotein cholesterol (LDL-C) reduces cardiovascular (CV) events. This has, however, not yet been shown in a real-world setting. We aimed to investigate the association between LDL-C changes and statin intensity with prognosis after a myocardial infarction (MI).

Methods and results 

Patients admitted with MI were followed for mortality and major CV events. Changes in LDL-C between the MI and a 6- to 10-week follow-up visit were analysed. The associations between quartiles of LDL-C change and statin intensity with outcomes were assessed using adjusted Cox regression analyses. A total of 40 607 patients were followed for a median of 3.78 years. The median change in LDL-C was a 1.20 mmol/L reduction. Patients with larger LDL-C reduction (1.85 mmol/L, 75th percentile) compared with a smaller reduction (0.36 mmol/L, 25th percentile) had lower hazard ratios (HR) for all outcomes (95% confidence interval): composite of CV mortality, MI, and ischaemic stroke 0.77 (0.70–0.84); all-cause mortality 0.71 (0.63–0.80); CV mortality 0.68 (0.57–0.81); MI 0.81 (0.73–0.91); ischaemic stroke 0.76 (0.62–0.93); heart failure hospitalization 0.73 (0.63–0.85), and coronary artery revascularization 0.86 (0.79–0.94). Patients with ≥50% LDL-C reduction using high-intensity statins at discharge had a lower incidence of all outcomes compared with those using a lower intensity statin.

Conclusions 

Larger early LDL-C reduction and more intensive statin therapy after MI were associated with a reduced hazard of all CV outcomes and all-cause mortality. This supports clinical trial data suggesting that earlier lowering of LDL-C after an MI confers the greatest benefit.