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SummaryThe Eurasian Griffon Vulture Gyps fulvus is a large Palearctic, Indohimalayan and Afrotropical Old-World vulture. The species’ range is vast, encompassing territories from the Pyrenees to the Himalayas. We reviewed and analysed a long-term data set for Griffon Vulture in the Balkans to estimate the change in its population size and range between 1980 and 2019. After a large historical decline, the Griffon Vulture population slightly increased in the last 39 years (λ = 1.02) and reached 445–565 pairs in 2019. We recorded a gradual increase of Griffon Vulture subpopulations in Serbia (λ = 1.08 ± 0.003), Bulgaria (λ = 1.08 ± 0.003) and Croatia (λ = 1.05 ± 0.005) and steep to a moderate decline of the species subpopulations in Greece (λ = 0.88 ± 0.005) and North Macedonia (λ = 0.94 ± 0.01). However, species range contracted to half of its former range in the same period. It occurred in 42 UTM squares in the 1980–1990 period and only 20 UTM squares between 2011 and 2019 and concentrated into three source subpopulations in Bulgaria, Serbia, and Croatia. Following reintroductions of the Griffon Vulture in Bulgaria, new colonies were formed at three novel localities after 2010. Regular movements of individuals between the different subpopulations exist nowadays. Therefore, preservation of both current and former core areas used for breeding and roosting is essential for species conservation in the region. However, the Griffon Vulture still faces severe threats and risk of local extinction. Various hazards such as poisoning, collision with energy infrastructure, disturbance and habitat alteration are depleting the status of the Balkan population and its full recovery. Further studies should analyse age-specific survival and mortality, recruitment, genetic relatedness, spatial use to inform the viability of this population in the future.

The semantic segmentation of robotic surgery video and the delineation of robotic instruments are important for enabling automation. Despite major recent progresses, the majority of the latest deep learning models for instrument detection and segmentation rely on large datasets with ground truth labels. While demonstrating the capability, reliance on large labelled data is a problem for practical applications because systems would need to be re-trained on domain variations such as procedure type or instrument sets. In this letter, we propose to alleviate this problem by training deep learning models on datasets that are synthesised using image-to-image translation techniques and we investigate different methods to perform this process optimally. Experimentally, we demonstrate that the same deep network architecture for robotic instrument segmentation can be trained on both real data and on our proposed synthetic data without affecting the quality of the output models’ performance. We show this for several recent approaches and provide experimental support on publicly available datasets, which highlight the potential value of this approach.

Various components and parameters of the free surface energy of a large number of polymer and metal surfaces have been estimated using the van Oss—Chaudhury–Good theory by the method of wetting with test liquids. All data are obtained by spatial processing of the specified equation. The values of the thermodynamic work of adhesion of polymer adhesives on metals have been calculated theoretically. The adhesion interaction of the polymer composite material–metal studied joints has been studied by the method of peeling under conditions of cathodic polarization. The correspondence between the adhesive strength of the joints and the work of adhesion of the polymer adhesive and metal has been found.

A rare live record of the loggerhead sea turtle Caretta caretta (Linnaeus, 1758) is reported from the Dzharylgach Gulf in the north-western Black Sea. This is the first record from Ukrainian waters since 1962 and the northernmost record of the species in the Black Sea. The loggerhead sea turtles of the east Mediterranean origin are increasingly often seen in the Marmara and the Black Sea during the latest decade, which is an evidence for potential expansion of this species range, at least partly due to climate changes. Key words: sea turtles, Caretta caretta, Black Sea, Ukraine, range expansion.

Scientific reports 10(1), 21981 (2020). doi:10.1038/s41598-020-78613-7, Published by Macmillan Publishers Limited, part of Springer Nature, [London]

Funder: Royal Academy of Engineering; doi: https://doi.org/10.13039/501100000287, Funder: Pembroke College, University of Oxford (Pembroke College Oxford); doi: https://doi.org/10.13039/100010355, Funder: Nederlandse Organisatie voor Wetenschappelijk Onderzoek (Netherlands Organisation for Scientific Research); doi: https://doi.org/10.13039/501100003246, The dynamical arrest of attractive colloidal particles into out-of-equilibrium structures, known as gelation, is central to biophysics, materials science, nanotechnology, and food and cosmetic applications, but a complete understanding is lacking. In particular, for intermediate particle density and attraction, the structure formation process remains unclear. Here, we show that the gelation of short-range attractive particles is governed by a nonequilibrium percolation process. We combine experiments on critical Casimir colloidal suspensions, numerical simulations, and analytical modeling with a master kinetic equation to show that cluster sizes and correlation lengths diverge with exponents ~1.6 and 0.8, respectively, consistent with percolation theory, while detailed balance in the particle attachment and detachment processes is broken. Cluster masses exhibit power-law distributions with exponents −3/2 and −5/2 before and after percolation, as predicted by solutions to the master kinetic equation. These results revealing a nonequilibrium continuous phase transition unify the structural arrest and yielding into related frameworks.

In this article, the authors construct portfolios by integrating quantitative factors in the portfolio optimization problem using their normalized score values in a constraint. The resulting optimized portfolios are tilted by the factor exposures controlled by the scoring constraint. The authors test the performance of the mean–variance optimization problem using scores of three value factors (book-to-price, earnings-to-price, cash flow-to-enterprise value) and the momentum factor. Optimized portfolios constrained with the book-to-price and momentum factor deliver the best results in terms of mean and risk-adjusted return. The combination of book-to-price and momentum factor portfolios further improves the risk-adjusted return. The results of this method are comparable with those of the portfolio optimization based on the estimation of the standard stock selection models. TOPICSAnalysis of individual factors/risk premia, factor-based models, portfolio construction Key Findings ▪ The authors assess the usefulness of a factor score as a proxy for the stock expected return in the construction of factor-tilted portfolios. ▪ The approach is tested on well-known cross-sectional factor strategies based on the momentum factor and three value factors. ▪ The authors consider a two-step approach in which individual value and momentum factor-tilted optimized portfolios are combined.

We consider travelling times of billiard trajectories in the exterior of an obstacle K on a two-dimensional Riemannian manifold M. We prove that given two obstacles with almost the same travelling times, the generalised geodesic flows on the non-trapping parts of their respective phase-spaces will have a time-preserving conjugacy. Moreover, if M has non-positive sectional curvature, we prove that if K and L are two obstacles with strictly convex boundaries and almost the same travelling times then K and L are identical.

The effect of polycarboxylate ether and a complex hydrophobic–plasticizer additive on the structure and mineral composition of soil cement based on kaolinite clay with kaolinite content of more than 95% was studied. Research methods included X-ray phase analysis, differential scanning calorimetry, and electron-scanning microscopy. Patterns of the effect of polycarboxylate ether and a complex hydrophobic–plasticizer additive on the formation of Portland cement hydration products in strengthened clay were determined, and changes in the structure of modified samples of soil cement based on kaolinite clay were revealed.

In recent years, Lithium-ION (LI-ION) battery packs have been the dominant energy storage system (ESS) in electrified transportation applications such as material handling, robotics, and electric vertical takeoff and landing aircraft. These applications prefer a high-energy-density and lightweight ESS owing to size and weight limitations. However, they are often equipped with an oversized battery pack to mitigate the long downtime due to the low charging rates (1C) of high-energydensity Li-ion batteries. Fast charging is a potential solution to create a "filling a tank" experience that has recently drawn tremendous interest from researchers and the industry.

One of the guiding principles of the Fourth Industrial Revolution is the need for lifelong learning. This determines the growing role of intelligent educational systems to provide the necessary learning resources and services to users at any time and any place. This article presents the modeling and development of an intelligent multi-agent learning environment for the secondary school, developed by a team of the DeLC laboratory at the University of Plovdiv “Paisii Hilendarski”, Bulgaria. The learners are placed at the focus of the environment by personal assistants supporting work with the environment.

It was found that at room temperature the value of the photoinduced current of Schottky diodes based on heterostructures InP/GaInAs/Pd at a hydrogen concentration of 0.03% is reduced by two orders of magnitude compared to the value without hydrogen. The value of the photoinduced current depends on the thickness of the depleted region on the surface of the semiconductor. A small change in the charged layer of H+ can cause a significant change in the thickness of this region and as a result, a strong change in the photoinduced current. This effect on current is much stronger than the influence of hydrogen concentration or capacitance without optical activation. As a result, it becomes possible to create hydrogen and hydrogen-containing gas sensors with much better sensitivity at room temperature. The original design of a miniature H2 sensor including an IR LED, a Schottky diode with a Pd contact, a Peltier cooler and a thermosensor is demonstrated.

Systems consisting of ethylene–vinyl acetate copolymers and (aminoalkoxy)silanes are studied. The diffusion and mutual solubility of their components are investigated, and phase diagrams covering a broad range of composition and temperatures are constructed. We find that the near-surface layers of the modified copolymers are enriched with the organosilicon component. The effects that the phase structure of considered adhesives has on the energetic properties and adhesion strength for different types of substrates are identified.

The possibility of creating a multipurpose complex for generating a reference field of thermal neutrons based on a portable neutron source (PNS) is considered. It has been shown that our method can be used to detect fissile materials without determining their isotopic composition during an inspection of the hand luggage of passengers, mail, etc. The PNS multipurpose complex will allow to indirectly indicating the possible presence of chemical explosives in the test samples, as well as cadmium and boron, which possibly hide fissile elements from detection. The paper gives recommendations on the use of the most effective instruments and equipment.

We performed high-resolution optical spectroscopy and X-ray observations of the recently identified Mira-type symbiotic star EF Aql. Based on high-resolution optical spectroscopy obtained with SALT, we determine the temperature ($\sim $55 000 K) and the luminosity ($\sim$ 5.3 $L_\odot$) of the hot component in the system. The heliocentric radial velocities of the emission lines in the spectra reveal possible stratification of the chemical elements. We also estimate the mass-loss rate of the Mira donor star. Our Swift observation did not detect EF Aql in X-rays. The upper limit of the X-ray observations is 10$^{-12}$ erg cm$^{-2}$ s$^{-1}$, which means that EF Aql is consistent with the faintest X-ray systems detected so far. Otherwise we detected it with the UVOT instrument with an average UVM2 magnitude of 14.05. During the exposure, EF Aql became approximately 0.2 UVM2 magnitudes fainter. The periodogram analysis of the V-band data reveals an improved period of 320.4$\pm$0.3 d caused by the pulsations of the Mira-type donor star. The spectra are available upon request from the authors., Comment: Accepted for publication in MNRAS

This paper addresses retinal vessel segmentation on optical coherence tomography angiography (OCT-A) images of the human retina. Our approach is motivated by the need for high precision image-guided delivery of regenerative therapies in vitreo-retinal surgery. OCT-A visualizes macular vasculature, the main landmark of the surgically targeted area, at a level of detail and spatial extent unattainable by other imaging modalities. Thus, automatic extraction of detailed vessel maps can ultimately inform surgical planning. We address the task of delineation of the Superficial Vascular Plexus in 2D Maximum Intensity Projections (MIP) of OCT-A using convolutional neural networks that iteratively refine the quality of the produced vessel segmentations. We demonstrate that the proposed approach compares favourably to alternative network baselines and graph-based methodologies through extensive experimental analysis, using data collected from 50 subjects, including both individuals that underwent surgery for structural macular abnormalities and healthy subjects. Additionally, we demonstrate generalization to 3D segmentation and narrower field-of-view OCT-A. In the future, the extracted vessel maps will be leveraged for surgical planning and semi-automated intraoperative navigation in vitreo-retinal surgery.

Hypothesis Saponins are natural surfactants which can provide highly viscoelastic interfaces. This property can be used to quantify precisely the effect of interfacial dilatational elasticity on the various rheological properties of bulk emulsions. Experiments We measured the interfacial dilatational elasticity of adsorption layers from four saponins (Quillaja, Escin, Berry, Tea) adsorbed on hexadecane-water and sunflower oil-water interfaces. In parallel, the rheological properties under steady and oscillatory shear deformations were measured for bulk emulsions, stabilized by the same saponins (oil volume fraction between 75 and 85%). Findings Quillaja saponin and Berry saponin formed solid adsorption layers (shells) on the SFO-water interface. As a consequence, the respective emulsions contained non-spherical drops. For the other systems, the interfacial elasticities varied between 2 mN/m and 500 mN/m. We found that this interfacial elasticity has very significant impact on the emulsion shear elasticity, moderate effect on the dynamic yield stress, and no effect on the viscous stress of the respective steadily sheared emulsions. The last conclusion is not trivial, because the dilatational surface viscoelasticity is known to have strong impact on the viscous stress of steadily sheared foams. Mechanistic explanations of all observed effects are described.

For electronic packaging engineers in the high-reliability sectors, such as aerospace, defense, oil & gas, etc., the use of commercial off-the-shelf components offers significant advantages due to their high availability, fast delivery time, and low cost. However, these components pose significant reliability challenges due to the risks associated with tin whisker formation and uncertainty on the long-term reliability of lead-free solders. For addressing these risks, the hot solder dip process is used to refinish the package by replacing lead-free solder finishes with lead-based finishes to meet the stringent packaging and assembly requirements for these sectors, which are exempt from restriction of hazardous substances (RoHS) legislation. But the hot solder dip process is an extra process that exposes the package to an additional thermal load, which will result in thermomechanical stresses that need to be properly understood and controlled. For addressing this challenge, a multidisciplinary methodology combining thermomechanical models with “dip-to-destroy” experiments and scanning acoustic microscopy has been developed to identify the risk of package material delamination for a number of package designs. Results show that the developed models can predict delamination risks for a range of imposed thermal gradients. Electronic package designs with a direct heat path from dipped terminations to the internals of the package show a higher risk of overstress-induced delamination, and this failure is generally driven by the high-temperature excursion above the glass transition point of the molding compound. The novelty and significance of these findings is that the derived methodology can be used by electronic packaging designers to optimize the thermal parameters of the hot-solder-dip process so that subsequent refinished packages can meet the stringent high-reliability requirements for these sectors.

Golden jackal (Canis aureus) expansion in the last decades has triggered research interest in Europe. However, jackal phylogeny and taxonomy are still controversial. Morphometric studies in Europe found differences between Dalmatian and the other European jackals. Recent genetic studies revealed that African and Eurasian golden jackals are distinct species. Moreover, large Canis aureus lupaster may be a cryptic subspecies of the African golden jackal. Although genetic studies suggest changes in Canis aureus taxonomy, morphological and morphometric studies are still needed. The present study proposes the first comprehensive analysis on a wide scale of golden jackal skull morphometry. Extensive morphometric data of jackal skulls from Europe (including a very large Bulgarian sample), Asia Minor, and North Africa were analysed, by applying recently developed statistical tools, to address the following questions: (i) is there geographic variation in skull size and shape among populations from Europe, Anatolia and the Caucasus?, (ii) is the jackal population from the Dalmatian coast different?, and (iii) is there a clear distinction between the Eurasian golden jackal (Canis aureus) and the African wolf (Canis lupaster sensu lato), and among populations of African wolves as well? Principal component analysis and linear discriminant analysis were applied on the standardized and log-transformed ratios of the original measurements to clearly separate specimens by shape and size. The results suggest that jackals from Europe, Anatolia and the Caucasus belong to one subspecies: Canis aureus moreotica (I. Geoffroy Saint-Hilaire, 1835), despite the differences in shape of Dalmatian specimens. The present study confirmed morphometrically that all jackals included so far in the taxon Canis aureus sensu lato may represent three taxa and supports the hypothesis that at least two different taxa (species?) of Canis occur in North Africa, indicating the need for further genetic, morphological, behavioural and ecological research to resolve the taxonomic uncertainty. The results are consistent with recent genetic and morphological studies and give further insights on golden jackal taxonomy. Understanding the species phylogeny and taxonomy is crucial for the conservation and management of the expanding golden jackal population in Europe.

Western Canada’s oil sands hold the third-largest hydrocarbon deposits in the world. Bitumen, a very heavy petroleum, is currently recovered by surface mining with warm water or in situ. Recovery processes that use organic solvents are being developed to reduce water usage and tailings production. While solvent-based methods can effectively extract bitumen, removal of residual fine solids from diluted bitumen product (DBP) to meet the pipeline transport requirement of

The spectral parameters of midinfrared LED heterostructures with an InAs active region were studied experimentally, calculated using MATLAB, and simulated in COMSOL Multiphysics. The obtained data were compared to reveal the mechanism of formation of the emission spectra of these heterostructures. The results confirm that simulation is a promising design tool for LED structures.

The methylotrophic yeasts Ogataea (Hansenula) polymorpha and Komagataella phaffii (Pichia pastoris) have important industrial applications and are models for several biological processes including peroxisome biology and methanol metabolism. We examined the carbon source requirements for mating-type (MAT) switching and mating in both species. Haploid strains of O. polymorpha and K. phaffii are homothallic, and switch MAT by a flip/flop mechanism in which a chromosomal region containing the MAT genes undergoes an inversion. MAT switching is induced by nitrogen starvation in both species and can be detected 4-6 hr after induction. Both switching and mating require a utilizable carbon source that can be either fermentable or nonfermentable. We further observed that although methanol can be used as a sole carbon source in both species, it does not support the induction of MAT switching or mating. Our results provide insight into the nutritional cues that influence entry into sexual processes in methylotrophic yeasts that undergo flip/flop MAT switching.

A series of clays are studied as potentially effective fillers for polyolefins. For the purpose of achieving good interaction with the polymers, surface-energy and acid–base properties of clay powders are evaluated using the preferential wetting method. It is shown that the surface of the clay acquires a neutral character as a result of the modification.

We study the relationship between the well-known Carleman's condition guaranteeing that a probability distribution is uniquely determined by its moments, and a recent, easily checkable condition on...

We have analyzed some conditions which are essentially involved in deciding whether or not a probability distribution is unique (moment-determinate) or non-unique (moment-indeterminate) by its moments. We suggest new conditions concerning both absolutely continuous and discrete distributions. By using the new conditions, which are easily checkable, we either establish new results, or extend previous ones in both Hamburger case (distributions on the whole real line) and Stieltjes case (distributions on the positive half-line). Specific examples illustrate both the results and the relationship between the new conditions and previously available conditions., 15 pages

The knowledge in the behaviour and movement of endangered species is of key importance for the precise targeting and assessing the efficiency of nature conservation actions, especially considering vultures, which explore vast areas to locate ephemeral and unpredictable food resources. Therefore, a total of 51 Griffon Vultures (Gyps fulvus) from both the re-introduced population and the autochthonous Balkan Peninsula (Balkans) colonies have been tagged with GPS/GSM transmitters in recent years, in order to study their seasonal and spatial distribution. The current study presents the analysis of the high-resolution GPS location data, acquired between January 2016 and March 2021. A total of 1,138,383 locations (an average number of 23,716 ± 18,886 positions per bird, ranged between 2,515 and 76,431 of total fixes per bird; n=48) were used to estimate the home range size and identify the traditional foraging areas and roosting sites of the birds during the wintering, migration/roaming and summering periods. Our results reveal that Griffon Vultures movement activity and home range size varied considerably throughout the annual cycle, especially between their wintering and summering grounds, while exhibiting significant overlapping amongst the tracked individuals. Specifically, immature Griffon Vultures travel long distances across all Balkan Peninsula countries, but always gather with conspecifics, showing strong fidelity to active breeding/roosting sites. The total home range 95% area of the Griffon Vulture population on the Balkans was estimated at 39,986.4 km² and the 50% core area at 1,545.42 km² (n = 48). All tracked birds were found to either visit or frequently use (> 95% of the time) the same seven vulture key zones on the Balkan Peninsula – one in Serbia, one shared between North Macedonia and Bulgaria, one shared between Bulgaria and Greece, two entirely lying in Bulgaria, one in western Greece and one shared between Kvarner Archipelago islands in Croatia and the Julian Alps - Italy, Austria and Slovenia. Several smaller sub-zones were also defined within these general ones. The seven key zones form a coherent network and are used as stepping stones for Griffon Vultures during their migration movements and roaming, but also wintering and summering. The observed concentration tendency of Griffon Vultures on the Balkans and the predictability of their temporal and spatial presence should be used to precisely target, address and substantially increase the efficiency of the conservation measures in this marginal and, thus, still vulnerable meta-population.

In the world, it is planned to produce promising for the manufacture of radiopharmaceuticals of radioisotope copper-67 by the reaction of its production from zinc-68 under the influence of γ-radiation on an electron accelerator. The next major issue is the separation of copper and zinc. Extraction, ion exchange and thermal distillation of zinc have already been studied in detail. Co-precipitation of copper with low zinc and thermal distillation of organic compounds of metals is promising.

The system GeO2–TiO2 was studied experimentally at high pressure and temperature to measure the miscibility of the two components and to test its applicability as a temperature sensor in high-pressure experiments. Significant solubility between the two end-members was found, with two coexisting solid solutions at high pressure exhibiting mutual solubility that increases with temperature along a solvus. The two solid solution compositions at the solvus can be distinguished readily by X-ray diffraction. At higher temperatures, a complete solid solution exists between the two end-members. The complete solution occurs above a critical line in P–T space (a critical point at each pressure). The critical point is located near 1630 °C and mole fraction ${X_{{\rm{Ti}}{{\rm{O}}_{\rm{2}}}}} = 0.57$ at 6.6 GPa and changes by 60 ± 5° per GPa in the region from 4 to 7 GPa. A model for the shape of the solvus is developed using X-ray diffraction data points from a series of quench experiments and an in situ experiment, and the model is used to estimate the thermal gradients in a Kawai-type multianvil assembly.

This article presents the synthesis of a series of amides, based on the interaction of several 3-aminospirohydantoins with nalidixic acid. The target compounds were characterized by physicochemical parameters, IR, 1H and 13C NMR spectral data. The antimicrobial activity of the products obtained was determined against Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis, Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa and Salmonella abony, the yeasts Candida albicans and Saccharomyces cerevisiae and the molds Penicillium chrysogenum and Aspergillus niger. The relationship between structure and biological activity of the products obtained was discussed. It was found that the most effective compounds are tetralin (5f) and indane (5g) derivatives, which exhibit a pronounced antimicrobial activity against both tested Gram-positive and Gram-negative bacteria.

Four benzothiazolium crown ether-containing styryl dyes were prepared through an optimized synthetic procedure. Two of the dyes (4b and 4d) having substituents in the 5-position of the benzothiazole ring are newly synthesized compounds. They demonstrated a higher degree of trans–cis photoisomerization and a longer life time of the higher energy forms in comparison with the known analogs. The chemical structures of all dyes in the series were characterized by NMR, UV–vis, IR spectroscopy and elemental analysis. The steady-state photophysical properties of the dyes were elucidated. The stability constants of metal complexes were determined and are in good agreement with the literature data for reference dyes. The temporal evolution of trans-to-cis isomerization was observed in a real-time regime. The dyes demonstrated a low intrinsic fluorescence of their Ba2+ complexes and high yield of E/Z photoisomerization with lifetimes of the higher energy form longer than 500 seconds. Density functional theory (DFT) calculations at the B3LYP/6-31+G(d,p) level were performed in order to predict the enthalpies (H) of the cis and trans isomers and the storage energies (ΔH) for the systems studied.

The article proposes a semi-martingale approximation to a fractional Levy processes that is capable of capturing long and short memory in the stochastic process together with fat tails. We use the semi-martingale process in option pricing and empirically compare its performance to other option pricing models, including a stochastic volatility Levy process. We contribute to the empirical literature by being the first to report the implied Hurst index computed from observed option prices using the Levy process model. Calibrating the implied Hurst index of S&P 500 option prices in a period that covers the 2008 financial crisis, we find that the risk-neutral measure is characterized by a short memory in turbulent markets and a long memory in calm markets. TOPICS:Options, statistical methods, performance measurement

In this article, the authors discuss a general method for ranking portfolios that places few limitations on the portfolio constituents other than using publicly traded assets. The ranking scores reflect the expected reward investors would require for accepting the risks of the portfolio in the context of an asset pricing framework. The scores are computed through a factor model that acknowledges the factor return correlations. The authors illustrate the approach with a large universe of exchange-traded funds assuming a linear model with Fama–French–Carhart factors wherein factor premiums (i.e., expected returns) are proportional to factor volatilities. The empirical analysis implies that the most significant factors from the Fama–French–Carhart factor set driving the premiums are the market and the momentum factors.

Изучается связь между хорошо известным условием Карлемана, гарантирующим единственность определения вероятностного распределения своими моментами, и одним найденным недавно и легко проверяемым условием, связанным со скоростью роста моментов. С использованием методов асимптотической теории интегралов и привлечением свойств $W$-функции Ламберта показывается, что квадратичная скорость роста отношений последовательных моментов, как достаточное условие однозначной определенности, немногим более ограничительна, чем условие Карлемана. Выводится ряд следствий, одно из которых утверждает, что из условия Карлемана не вытекает условие Харди, хотя обратная импликация верна. Обсуждаются и другие смежные вопросы.

By theoretical and experimental methods it is demonstrated how a beam whose amplitude profile is X-modulated in azimuthal direction, with central dark non-vortex core, can be transformed into an array of five-vortex spot patterns. This beam undergoes Fraunhofer diffraction by a fork-shaped grating with integer topological charge (TC) p. The results show an interesting phenomenon: while the incident beam is without topological charge, in the output array of spots a five-vortex modulation on the higher-diffraction-order patterns is evident. It consists of a central vortex (whose value and sign of its TC depend on the diffraction order m) and four “satellite” vortices situated in the apices of a rotated square (whose signs depend on the diffraction order of the spot m, in which they are nested). An exception is made in the case when the product of the diffraction order and the fork-shaped grating TC is equal to two; Then, the central vortex is absent, but, the four ”satellite” vortices are present. The interference patterns of the diffracted wave field and a slightly inclined plane wave are obtained experimentally and numerically, confirming the presence of the vortices predicted by the theory and registering the value and sign of their TCs.

We study the receptive metric entropy for semigroup actions on probability spaces, inspired by a similar notion of topological entropy introduced by Hofmann and Stoyanov (Adv Math 115:54–98, 1995). We analyze its basic properties and its relation with the classical metric entropy. In the case of semigroup actions on compact metric spaces we compare the receptive metric entropy with the receptive topological entropy looking for a Variational Principle. With this aim we propose several characterizations of the receptive topological entropy. Finally we introduce a receptive local metric entropy inspired by a notion by Bowen generalized in the classical setting of amenable group actions by Zheng and Chen, and we prove partial versions of the Brin–Katok Formula and the local Variational Principle.

The Green Deal and increased nutritional needs are driving factors in human activities nowadays. Agriculture is an essential economic sector that can profit from the application of renewable energy sources by the assimilation of off-grid, arid and barren terrains. Power supplied by hybrid systems for water pumping is a solution for overcoming the stochastic character of the renewable energy sources. This paper presents a sizing methodology for a hybrid system with wind and PV generation and water tank storage, based on the consideration of the entire energy conversion chain with energy models and a one-year operation simulation. The PV generator is modeled using a reduced Durisch’s model, while for the wind generator a piecewise interpolation is used. The methodology is applied for sites in Bulgaria with specific agricultural crops and meteorological data. Combinations of PV (different technologies) and wind (different types) generators and water tank capacities are considered and discussed. The combinations are compared on the basis of three criteria: the investment cost, the satisfaction of crop requirements and system oversizing. The possibility for the introduction of battery storage is also examined. The results show some trends in the hybrid system sizing and the possibility to apply the proposed methodology for various sites, generators and crops.

One of the most commonly produced industrial chemicals worldwide, bisphenol A (BPA), is used as a precursor in plastics, resins, paints, and many other materials. It has been proved that BPA can cause long-term adverse effects on ecosystems and human health due to its toxicity as an endocrine disruptor. In this study, we developed an integrated MnO2/UV/persulfate (PS) process for use in BPA photocatalytic degradation from water and examined the reaction mechanisms, degradation pathways, and toxicity reduction. Comparative tests using MnO2, PS, UV, UV/MnO2, MnO2/PS, and UV/PS processes were conducted under the same conditions to investigate the mechanism of BPA catalytic degradation by the proposed MnO2/UV/PS process. The best performance was observed in the MnO2/UV/PS process in which BPA was completely removed in 30 min with a reduction rate of over 90% for total organic carbon after 2 h. This process also showed a stable removal efficiency with a large variation of pH levels (3.6 to 10.0). Kinetic analysis suggested that 1O2 and SO4•− played more critical roles than •OH for BPA degradation. Infrared spectra showed that UV irradiation could stimulate the generation of –OH groups on the MnO2 photocatalyst surface, facilitating the PS catalytic degradation of BPA in this process. The degradation pathways were further proposed in five steps, and thirteen intermediates were identified by gas chromatography-mass spectrometry. The acute toxicity was analyzed during the treatment, showing a slight increase (by 3.3%) in the first 30 min and then a decrease by four-fold over 2 h. These findings help elucidate the mechanism and pathways of BPA degradation and provide an effective PS catalytic strategy.

The current study investigates the content of sugars, organic acids, phenolic acids and flavonoids, as well as antioxidant and antimicrobial activity of Balkan-endemic Micromeria frivaldszkyana. Glucose was the most abundant sugar in the plant (2.77%), followed by fructose (1.18%) and galactose (0.82%). Eight organic acids were detected with quinic acid being in the highest content—556.3 mg/100 g DW. From the individual phenolic acids, rosmarinic acid was found in the most significant amounts (2040.1 ± 1.97 mg/100 g) and hesperidin was the major representative of flavonoids with content 131.2 ± 5.6 mg/100 g DW. The antioxidant activity of the plant was studied by six methods: 2,2′-diphenylpicrylhydrazyl (DPPH)—286.4 ± 10.43 mM TE/g, 2,2′azinobis (3)-ethylbenzthiazoline-6-sulfonic acid (ABTS)—358.4 ± 10.4 mM TE/g, ferric reducing antioxidant power (FRAP)—388.0 ± 32.4 mM TE/g, cupric reducing antioxidant capacity (CUPRAC)—905.6 ± 19.2 mM TE/g, Oxygen Radical Absorbance Capacity (ORAC)—3250.5 ± 208.1 µmol TE/g and Hydroxyl Radical Averting Capacity (HORAC)—306.1 ± 23.5 µmol GAE/g. In vitro antimicrobial activity against nine microorganism was evaluated but the extract displayed antimicrobial activity only against Listeria monocytogenes ATCC 19111 with inhibition zone diameter 9 mm and minimal inhibitory concentration (MIC) 10 mg/mL.

Therapeutically relevant proteins such as GPCRs, antibodies and kinases face clear limitations in NMR studies due to the challenges in site‐specific isotope labeling and deuteration in eukaryotic expression systems. Here we describe an efficient and simple method to observe the methyl groups of leucine residues in proteins expressed in bacterial, eukaryotic or cell‐free expression systems without modification of the expression protocol. The method relies on simple stereo‐selective 13C‐labeling and deuteration of leucine that alleviates the need for additional deuteration of the protein. The spectroscopic benefits of “local” deuteration are examined in detail through Forbidden Coherence Transfer (FCT) experiments and simulations. The utility of this labeling method is demonstrated in the cell‐free synthesis of bacteriorhodopsin and in the insect‐cell expression of the RRM2 domain of human RBM39., Methyl‐based magnetization usage can strongly benefit investigations of large protein systems via NMR spectroscopy. Here, a simple and cost‐effective method to obtain locally deuterated leucine suitable for methyl NMR and to quantify its benefits is presented. The approach substantially expands the applicability of methyl labeling in emerging expression systems including cell‐free and eukaryotic systems.

Background: Online education became mandatory for many students during the Coronavirus disease 2019 (COVID-19) pandemic and blurred the distinction between settings where processes of stress and restoration used to take place. The lockdown also likely changed perceptions of the indoor acoustic environment (i.e., soundscape) and raised its importance. In the present study, we seek to understand how indoor soundscape related to university students’ self-rated health in Bulgaria around the time that the country was under a state of emergency declaration caused by the COVID-19 pandemic. Methods: Between 17 May and 10 June 2020, we conducted a cross-sectional online survey among 323 students (median age 21 years, 31% male) from two universities in the city of Plovdiv, Bulgaria. Self-rated health (SRH) was measured with a single-item. Participants were asked how frequently they heard different types of sounds while at home and how pleasant they considered each of those sounds to be. Restorative quality of the home (the “being away” dimension of the Perceived Restorativeness Scale) was measured with a single-item. A priori confounders and effect modifiers included sociodemographics, house-related characteristics, general sensitivity to environmental influences, and mental health. Our analysis strategy involved sequential exploratory factor analysis (EFA), multivariate linear and ordinal regressions, effect modification tests, and structural equation modeling (SEM). Results: EFA supported grouping perceived sounds into three distinct factors—mechanical, human, and nature sounds. Regression analyses revealed that greater exposure to mechanical sounds was consistently associated with worse SRH, whereas no significant associations were found for human and nature sounds. In SEM, exposure to mechanical sounds related to lower restorative quality of the home, and then to poorer SRH, whereas nature sounds correlated with higher restorative quality, and in turn with better SRH. Conclusions: These findings suggest a role of positive indoor soundscape and restorative quality for promoting self-rated health in times of social distancing.

The current study presents and analyses the results from the recently completed 11-year-establishment phase, following the start of the local re-introduction of the Griffon Vulture (Gyps fulvus) in Kotlenska Planina SPA and Sinite Kamani Nature Park in the Eastern Balkan Mountains of Bulgaria in the period 2010-2020. As a result of the re-introduction efforts and release of 153 individuals, the Griffon Vulture has been successfully reproducing again in the Eastern Balkan Mountains since 2016, after more than 40-50 years of absence. At 2020, the local population consists of some 80 local and up to 80-115 birds, together with sojourn individuals. Amongst them, 23-25 breeding pairs, located in five different colonies and two more frequently used roosting sites. The current average productivity remains relatively low: 0.41 fledglings/territorial pair and fledging success of 0.61 fledglings/breeding pair between 2016 and 2020, but shows a trend to increase with time and the growing experience of the young locally re-introduced population. The mortality confirmed between 2010-2021 accounts for 33%, mostly due to electrocution as a post-release effect in the first six months following their release. Our data show that the newly established population in the Eastern Balkan Mountains mostly forages on feeding sites, having a comparatively small 95% home range: 281.88 ± 91 km2 and 50% core area: 6.6 ± 2.28 km2 (range 4.7–8.5 km2). We, therefore, consider the establishment phase of the re-introduction of Griffon Vulture in this particular site as successfully completed, but management should continue. Furthermore, the area of the Eastern Balkan Mountains can currently be regarded as a "source" for the species within the source-sink population regulation concept in the national and Balkan context.

Betonica bulgarica is an endemic species distributed in Bulgaria. The chemical composition of the essential oil analysed by GC&ndash, MS (Gas chromatography&ndash, mass spectrometry) and the content of trace elements analysed by ICP&ndash, MS (Inductively coupled plasma mass spectrometry) were determined. Additionally, a study on the types and distribution of trichomes was done using a microscope with a camera. The essential oil was characterized using a high concentration of sesquiterpene hydrocarbons, whose major compounds are &beta, caryophyllene (17.4%), germacrene D (9.9%), and &beta, bourbonene (6.7%). The contents of manganese (177.2 &micro, g/g) and strontium (156.8 &micro, g/g) were highest among the investigated micronutrients. Two types of trichomes were identified on the adaxial and abaxial epidermises of the leaves of B. bulgarica&mdash, covering and glandular. Peltate stacked glandular trichomes with a four-celled head of type B were observed on the leaf surface.

A synthetic approach for preparation of a new class of 1,8-naphthalimide derivatives with fused benzo and naphtho-dioxin systems is reported. The proposed reaction conditions for the first step allow selective bromination of 1,8-naphthalic anhydride to the corresponding 3,4,6-tribromo derivative, which has the potential to be versatile building block in the chemistry of naphthalimides. The dioxin-annulated products were isolated in very good yields and their applicability for further modifications by metal-catalysed coupling reactions was proven. The synthesized fluorescent dyes showed media dependant emission and their photophysical and electroluminescent properties were evaluated with respect to their application in OLED. TGA measurements showed that all compounds are stable up to above 400 °C. The best OLED test device has turn-on voltage of 8 V; maximum luminescent intensity of 3031 cd/m2, and current efficiency of 6.9 cd/A.

This paper compares the thermomechanical behavior of 3D inkjet printed microelectronics devices relative to those fabricated from traditional methods. It discusses the benefits and challenges in the adoption of additive manufacturing methods for microelectronics manufacture relative to conventional approaches. The critical issues related to the design and reliability of additively manufactured parts and systems stem from the change in the manufacturing process and the change in materials utilized. This study uses numerical modelling techniques to gain insight into these issues. This article is an extension of a paper on the same topic presented at the 2018 IEEE Electronics Packaging Technology Conference [1] An introduction providing an overview of the area, covering salient academic research activities and discussing progress towards commercialization is presented. The state-of-the-art modular microelectronics fabrication system developed within the EU NextFactory project is introduced. This system has been used to manufacture several test samples, which were assessed both experimentally and numerically. A full series of JEDEC tests showed that the samples were reliable, successfully passing all tests. The numerical model assessing the mechanical behavior of an inkjet-printed structure during layer-by-layer fabrication is presented. This analysis predicts that the stresses induced by the UV cure process are concentrated toward the extremities of the part and, in particular, in the lower layers which are constrained by the print platform. Subsequently, a model of a multilayer microelectronics structure undergoing JEDEC thermal cycling is presented. The model assesses the differences in mechanical properties between a conventional FR4/copper structure and an inkjet-printed acrylic/silver structure. The model identified that the influence of the sintering process on subsequent material properties, behavior of the inject-printed structure, and reliability of the inject-printed structure is significant. Key findings are that while stresses in the conventional and inkjet boards are relatively similar, the inkjet-printed board exhibits significantly greater deformation than the standard board. Furthermore, the mechanical stresses in the inkjet fabricated board are strongly dependent on the elastic modulus of the sintered silver material, which, in turn, is dependent on the sintering process.

In this paper, we study the role of the symmetry energy on the neutron-drip transition in both nonaccreting and accreting neutron stars, allowing for the presence of a strong magnetic field as in magnetars. The density, pressure, and composition at the neutron-drip threshold are determined using the recent set of the Brussels-Montreal microscopic nuclear mass models, which mainly differ in their predictions for the value of the symmetry energy $J$ and its slope $L$ in infinite homogeneous nuclear matter at saturation. Although some correlations between on the one hand the neutron-drip density, the pressure, the proton fraction and on the other hand $J$ (or equivalently $L$) are found, these correlations are radically different in nonaccreting and accreting neutron stars. In particular, the neutron-drip density is found to increase with $L$ in the former case, but decreases in the latter case depending on the composition of ashes from x-ray bursts and superbursts. We have qualitatively explained these different behaviors using a simple mass formula. We have also shown that the details of the nuclear structure may play a more important role than the symmetry energy in accreting neutron-star crusts., Comment: 29 pages, 9 figures

As producers of biomass, cyanobacteria are a major part of the phytoplankton in a large number of water basins. Due to the cyanobacterial blooms and cyanotoxins produced, these organisms are recognized as a threat and ecological risk for water bodies. Released cyanotoxins may cause death of many organisms including birds and fish. Vaya Lake is the largest natural lake in Bulgaria. It is located on the Via Pontica migration route of birds between Europe and Africa. Since 2003, the lake has been declared as a "Wetland of international importance” under the Ramsar Convention. According to the literature data from 2002-2006, the Lake is defined as highly eutrophied due to strong anthropogenic pressure, but regular monitoring of the cyanobacterial blooms and presence of cyanotoxins after this period is missing. Taking into account the importance of this unique, protected ecosystem, our aim was to make a complete ecological assessment of the present state of Lake Vaya by using the phytoplankton, with an emphasis on cyanobacterial blooms and the presence of cyanotoxins. As results of the study, we 1) characterized the phytoplankton composition qualitatively and quantitatively; 2) evaluated the ecological status of the western and eastern part of the Lake; 3) identified the potential producers of cyanotoxins; 4) observed cyanobacterial blooms and discussed the influence of macrophytes on their spread; 5) measured the concentrations of the cyanotoxins MCs, CYL and STXs in water samples from both parts of the Lake. Our results indicated the need for continued observation of cyanobacterial composition, blooming and the presence of cyanotoxins in Lake Vaya.

There are ongoing social debates about the risks and benefits of using nuclear reactors to generate electricity. Radiation accidents can occur for different reasons and even be caused deliberately as a result of terrorist actions, and these may affect from a few to thousands of people. After a major release of radioactive iodine as a result of a nuclear accident, large number of potentially affected people may require rapid assessments to determine the degree of thyroid contamination, especially children and young people given that their thyroid is a highly radiosensitive organ and particularly vulnerable to the carcinogenic action of ionising radiation. To date, there is no internationally agreed protocol for measuring 131I in the thyroid of affected persons, especially in children. To address this problem, the Child and Adult Thyroid Monitoring After Reactor Accident (CAThyMARA) project ( https://www.eu-neris.net/projects/operra/operra-cathymara.html ) focused on post-accidental 131I measurements in the thyroid, giving special attention to children and involved 15 institutions from 12 European countries. One of the Work Packages of the project had the objective to overview existing national plans and means for thyroid monitoring and to review international recommendations about radioiodine monitoring in the thyroid in case of a large scale nuclear accident. To achieve this objective, a questionnaire-based survey was carried out from May to October 2016. The survey results were based on the analysis of the answers of 31 institutions in 18 European countries, which included a wide range of questions related to emergency plan strategies, monitoring strategies for radioiodine in thyroid, dose assessment, etc. In addition, the peer-review literature in this area was reviewed and summarised. The results of the survey together with the current international recommendations about radioiodine monitoring in thyroid could provide important information on existing gaps, which can be used to develop new or update existing guidelines on thyroid monitoring after a nuclear accident.

The design of hydrogels where multiple interpenetrating networks enable enhanced mechanical properties can broaden their field of application in biomedical materials, 3D printing, and soft robotics. We report a class of self-reinforced homocomposite hydrogels (HHGs) comprised of interpenetrating networks of multiscale hierarchy. A molecular alginate gel is reinforced by a colloidal network of hierarchically branched alginate soft dendritic colloids (SDCs). The reinforcement of the molecular gel with the nanofibrillar SDC network of the same biopolymer results in a remarkable increase of the HHG’s mechanical properties. The viscoelastic HHGs show >3× larger storage modulus and >4× larger Young’s modulus than either constitutive network at the same concentration. Such synergistically enforced colloidal-molecular HHGs open up numerous opportunities for formulation of biocompatible gels with robust structure-property relationships. Balance of the ratio of their precursors facilitates precise control of the yield stress and rate of self-reinforcement, enabling efficient extrusion 3D printing of HHGs., Composites which are made up of a single polymer, and yet allow modulation of the mechanical properties of the matrix without stress concentration, are challenging to fabricate. Here, the authors design a selfreinforced homocomposite alginate hydrogel with enhanced mechanical properties incorporating soft dendritic alginate colloids in the matrix and demonstrate its application in extrusion printing.

Background An Israeli national taskforce performed a multi-center clinical and analytical validation of seven serology assays to determine their utility and limitations for SARS-CoV-2 diagnosis. Methods Serology assays from Roche, Abbott, Diasorin, BioMerieux, Beckman-Coulter, Siemens, and Mt.-Sinai ELISA were included. Negative samples from 2391 individuals representative of the Israeli population, and 698 SARS-CoV-2 PCR positive patients, collected between March and May 2020, were analyzed Findings Immunoassays sensitivities between 81.5%-89.4% and specificities between 97.7%-100% resulted in a profound impact on the expected Positive Predictive Value (PPV) in low (

The GNSS system allows on a planetary scale to fulfill navigation functions, that is, to determine the current location of consumers of navigation information and their speed and to carry out accurate time on the Earth's surface and in near-Earth space. There are several sources of errors that distort the code and the carrier of the navigation signal. The noise floor of the receiver error and the errors from multipath propagation of the signal are independent for each receiver. Multipath propagation of the signal is the main source of errors for high-precision navigation. In this paper we propose a methods for estimation of these errors, which are based on the properties of the time correlation of the multipath propagation of the navigation signal.