bluuebunny/crossref_metadata_2025 huggingface dataset:
Electromagnetic ion cyclotron instability stimulated by the suprathermal ions in space plasmas: A quasi-linear approach
Authors: Shaaban S. M. , Lazar M. , Schlickeiser R.
Published: February 2021

In collision-poor space plasmas, protons with an excess of kinetic energy or temperature in the direction perpendicular to the background magnetic field can excite the electromagnetic ion cyclotron (EMIC) instability. This instability is expected to be highly sensitive to suprathermal protons, which enhance the high-energy tails of the observed velocity distributions and are well reproduced by the (bi-)Kappa distribution functions. In this paper, we present the results of a refined quasi-linear approach, able to describe the effects of suprathermal protons on the extended temporal evolution of EMIC instability. It is, thus, shown that suprathermals have a systematic stimulating effect on the EMIC instability, enhancing not only the growth rates and the range of unstable wavenumbers but also the magnetic fluctuating energy density reached at the saturation. In effect, the relaxation of anisotropic temperature also becomes more efficient, i.e., faster in time and closer to isotropy.
Machinable boron-doped diamond as a practical heating element in multi-anvil apparatuses
Authors: Xie Longjian
Published: February 2021

Being refractory and X-ray transparent, a boron-doped diamond (BDD) heater is considered an ideal heating element in a multi-anvil apparatus under diamond-stable pressures. However, the extremely high hardness of diamond makes it difficult to manufacture a BDD tube, which, in turn, hinders the wide application of BDD heaters in multi-anvil apparatuses. Here, I sintered a machinable BDD (MBDD) from a mixture of BDD powder and pitch (CnH2n+2) by its annealing in Ar at 1273 K for 5 h. The BDD powder was bound by a small amount of graphite (<10 wt. %) during the sintering process. Tubes (such as 1.2/0.7/4.0 mm in outer/inner diameter/length) can be manufactured from the MBDD block using a lathe or a computer numerical control machine. Due to the low content of graphite in MBDD, the graphite–diamond conversion has a small effect on heating performance. The MBDD heater shows a comparable performance in ultrahigh temperature generation with a high-pressure synthesized BDD heater by generating a temperature higher than 3300 K and melted Al2O3 under a pressure of 15 GPa. With good heating performance and excellent machinability, MBDD is a practical heating element in multi-anvil apparatuses. The achievement of stable temperature generation over 3300 K by the MBDD heater enables various measurements on the physicochemical properties of melts under the Earth’s mantle conditions.
Extended Lagrangian Born–Oppenheimer molecular dynamics for orbital-free density-functional theory and polarizable charge equilibration models
Authors: Niklasson Anders M. N.
Published: February 2021

Extended Lagrangian Born–Oppenheimer molecular dynamics (XL-BOMD) [A. M. N. Niklasson, Phys. Rev. Lett. 100, 123004 (2008)] is formulated for orbital-free Hohenberg–Kohn density-functional theory and for charge equilibration and polarizable force-field models that can be derived from the same orbital-free framework. The purpose is to introduce the most recent features of orbital-based XL-BOMD to molecular dynamics simulations based on charge equilibration and polarizable force-field models. These features include a metric tensor generalization of the extended harmonic potential, preconditioners, and the ability to use only a single Coulomb summation to determine the fully equilibrated charges and the interatomic forces in each time step for the shadow Born–Oppenheimer potential energy surface. The orbital-free formulation has a charge-dependent, short-range energy term that is separate from long-range Coulomb interactions. This enables local parameterizations of the short-range energy term, while the long-range electrostatic interactions can be treated separately. The theory is illustrated for molecular dynamics simulations of an atomistic system described by a charge equilibration model with periodic boundary conditions. The system of linear equations that determines the equilibrated charges and the forces is diagonal, and only a single Ewald summation is needed in each time step. The simulations exhibit the same features in accuracy, convergence, and stability as are expected from orbital-based XL-BOMD.
Charge coloration dynamics of electrochromic amorphous tungsten oxide studied by simultaneous electrochemical and color impedance measurements
Authors: Rojas-González Edgar A. , Niklasson Gunnar A.
Published: February 2021

The coloration mechanisms in electrochromic systems can be probed by comparing the dynamics of the electrical and optical responses. In this paper, the linear frequency-dependent electrical and optical responses of an amorphous tungsten oxide thin film were measured simultaneously by a combination of two techniques—that is, electrochemical impedance spectroscopy (EIS) and the so-called color impedance spectroscopy. This was done at different bias potentials and their associated intercalation levels. Equivalent circuit fitting to the EIS spectra was used to extract the Faradaic components from the total impedance response. The latter were assigned to an intermediate adsorption step before the intercalation and to the diffusion of the electron–ion couple in the film. A quantity denoted complex optical capacitance was compared to the complex electrical capacitance—particularly, their expressions are related to the Faradaic processes. The coloration at low intercalation levels followed both the adsorption and diffusion phenomena. Conversely, the diffusion contribution was dominant at high intercalation levels and the adsorption one seemed to be negligible in this case. The complex spectra of perfectly synchronized electrical and optical responses are expected to differ only by a multiplying factor. This was the case at low intercalation levels, apart from small deviations at high frequencies. A clear departure from this behavior was observed as the intercalation level increased. A combination of frequency-dependent techniques, as presented here, can help to elucidate the dynamics of the coloration mechanisms in electrochromic materials at various conditions—for example, at different intercalation levels and optical wavelengths.
Tunable terahertz band-stop filter using strongly coupled split ring resonators integrated with on-chip waveguide
Authors: Parker-Jervis Rowan S. , Park Sae June , Cunningham John E.
Published: February 2021

We have used finite-element methods to design and simulate a tunable terahertz frequency range band-stop filter based on coupled split-ring resonators integrated into planar Goubau-line waveguide. Two split-ring resonators with different geometrical lengths and gap widths were designed to resonate at the same frequency. When the two resonators were coupled, resonance splitting was observed in the transmission spectra controlled by the distance between them. The electric field distribution and surface current modes in the coupled resonators were used to identify the origin of the resonance modes. In order to dynamically tune the coupled resonance frequencies, a cantilevered microelectromechanical scheme is proposed, in which the radius of curvature of one split-ring resonator is adjusted with respect to a fixed second split-ring resonator. The coupling strength of the coupled resonators was investigated as a function of the relative separation of the resonators revealing a dispersion relation that shows anti-crossing of the coupled resonances as the cantilever bends.
Fermi level pinning and band bending in
δ
-doped BaSnO3
Authors: Kim Youjung , Cho Hyeongmin , Char Kookrin
Published: February 2021

Various δ-doped semiconductor heterostructures have been effectively used for devices at room temperature and for quantum phenomena at low temperatures. Here, we use BaSnO3 and investigate its δ-doped system, focusing on its band bending and surface boundary conditions. We measured the two-dimensional carrier density (n2D) of the δ-doped BaSnO3 system of various thicknesses and doping levels. We also studied the effect of the BaSnO3 capping layer thickness on n2D. We show that the δ-doped BaSnO3 system can be very well described by band bending with the aid of the Poisson–Schrödinger simulation. At the same time, the capping layer thickness dependence of n2D reveals how the boundary condition on the surface of La-doped BaSnO3 evolves as a function of its capping layer thickness.
Compact model of nanometer STT-MTJ device with scale effect
Authors: Wang Manman , Jiang Yanfeng
Published: February 2021

The emergence and growing maturity of spintronics present new ideas and methods for low-power integrated circuit design. Spin-transfer torque magnetic tunnel junction (STT-MTJ) device is one of the spintronic candidates for future promising non-volatile memory. In this paper, a compact model for the STT-MTJ device in nanoscale is presented. By analyzing the influence of the device scale on its properties, the scale effect of the MTJ device is included. The thermal stability factor is trimmed to reflect the error rate of the scale effect of the device. Based on the compact model, the simulation is conducted with different device sizes to present the influence of the scale effect on the device characteristics, including the resistance, the critical current, the switching time, the write error rate, and other characteristics.
Field-induced phase transitions of tetramer-singlet states in synthetic SU(4) magnets
Authors: Miyazaki Y. , Yamamoto D. , Marmorini G. , Furukawa N.
Published: February 2021

Phase transitions of quantum dimer magnets can be explained in terms of Bose-Einstein condensation of magnons. Here we consider a natural extension of the dimer magnets to SU(4)-symmetric tetramer systems, which could be created with four nuclear-spin components (named “u,” “d,” “c,” and “s”) of 173Yb atoms in optical superlattices. We apply the cluster mean-field approximation to the SU(4) Heisenberg model on a tetramerized square lattice, and study the phase transition phenomena in the presence of the field that creates a population imbalance between the two components u,d and the other two c,s. When the population of the four components is balanced, the ground state is approximately given by the direct product of local SU(4)-singlet states. When the field is applied, the population ratio of the components u and d is increased and the system eventually reaches a “saturated” state, which is a SU(2) system with only u and d. We show that in the saturation process, the system exhibits two successive step-like transitions, in contrast to the standard dimer magnets with continuous transition process associated with Bose-Einstein condensation of magnons. The intermediate phase in between the two step-like transitions is a nontrivial solid phase with alternating arrangement of the SU(4)-singlet and four-site resonating-valence-bond states.
California dreamin’
Authors: Leslie Stuart J.
Published: February 2021

Defense projects made the West Coast the promised land for US physicists after World War II—until the projects dried up.
Relativistic quantum chaos in graphene
Authors: Xu Hong-Ya , Huang Liang , Lai Ying-Cheng
Published: February 2021

Classical chaos gains some additional degrees of freedom in materials with excitations described by the Dirac equation.
Whiskey webs: Fingerprints of evaporated bourbon
Authors: Williams Stuart J.
Published: February 2021

When a water-diluted droplet of American whiskey evaporates, it can leave behind a self-assembled web pattern not found in Scotch or brandy.
fermentation characteristics of tropical legumes and grasses of good and poor nutritional quality and the degradability of their neutral detergent fibre
Authors: Castro-Montoya J. M. , Goetz K. , Dickhoefer U.
Published: February 2021

Context Tropical legumes are commonly assumed to share all positive attributes known from temperate legumes such as lucerne. However, increasing evidence exists on the differences between those forages, particularly in terms of their ruminal degradability. Aims Exploring the 24-h rumen in vitro-fermentation characteristics of tropical legumes, their direct comparison with lucerne, and their interactions with grasses depending on their nutritional quality. Methods Arachis and stylosanthes (tropical legumes), pennisetum and andropogon (tropical grasses), and lucerne (lucerne_21 and lucerne_35, harvested 21 and 35 days after emergence respectively) were used for the study. On the basis of the nitrogen and neutral detergent fibre (NDF) concentration, arachis and pennisetum were classified as of good quality, while stylosanthes and andropogon as of poor quality. The following four incubation series were performed: first, forages alone were incubated under iso-nitrogenous conditions; second, forages were incubated under iso-nitrogenous conditions with supplemented starch; third, NDF extract of each forage was incubated alone; fourth, NDF extract of tropical grasses and legumes was incubated combined in grass : legume proportions of 33 : 67 and 67 : 33. Key results When incubated alone, gas production (GP) and total short chain fatty acids were higher for temperate legumes, intermediate for tropical legumes and lowest for tropical grasses. Similar trends were observed for GP when the forages were incubated with starch, but the differences between arachis and lucerne_35 disappeared; short chain fatty acids did not differ among all tropical forages. Moreover, acetate : propionate ratio was highest for tropical legumes, intermediate for temperate legumes, and lowest for tropical grasses. Gas production of NDF extracts was highest for the lucerne samples and lowest for the tropical legumes. Improvements in GP were found when the NDF from the poor-quality grass (andropogon) was combined with the legumes, particularly the good-quality legume (arachis). Conclusions On the basis of the gas production, tropical legumes appear to have lower degradability than do temperate ones, while also showing a different fermentation pattern. Fibre of tropical legumes is less degradable than that of tropical grasses, but when combining both fibre sources, there seems to be a synergistic effect on degradability. Implications The current results give important insights on the fermentation characteristics of tropical legumes, helping better understand their role in ruminants’ nutrition, while giving inputs towards improving their utilisation.
Analysis of culling reasons and age at culling in Australian dairy cattle
Authors: Wondatir Workie Zewdie , Gibson John P. , van der Werf Julius H. J.
Published: February 2021

Context A thorough analysis of the reasons for culling was made to understand the phenotypic trend in herd life. In addition, identification of culling reasons could enable to develop a strategy for further evaluation of longevity in Australian dairy cows. Aims The aim of this study was to investigate the main causes of culling in Australian dairy herds and thereby to assess the trend of reason-specific culling over time. Methods Culling reasons in Australian dairy cattle were studied based on culling records from 1995 through 2016. A total of 2  452 124 individual cow culling observations were obtained from Datagene, Australia, of which 2 140 337 were Holstein and 311 787 were from Jersey cows. A binary logistic regression model was used to estimate effects of breed and age and the trend of a particular culling reason over time. Key results The most important culling reasons identified over the 21-year period were infertility (17.0%), mastitis (12.9%), low production (9.3%), sold for dairy purpose (6.4%) and old age (6.2%), whereas 37.4% were ‘other reasons not reported’. The average age at culling was nearly the same for Holstein (6.75 years) and Jersey (6.73 years) cows. The estimated age at culling was slightly increased for Holstein cows (by 3.7 days) and somewhat decreased for Jersey cows (by 11 days) over the last two decades. The probability of culling cows for infertility and low production was high in early parities and consistently declined as age advanced, and culling due to mastitis was higher in older cows. The trend of main culling reasons over time was evaluated, indicating that the probability of culling due to infertility has progressively increased over the years in both breeds, and culling for mastitis in Jersey cows has also increased. Culling of cows due to low production sharply decreased from 2.5 to –8% for Holstein and from 73 to 60% for Jersey cows over the 21-year period. Conclusions Culling age has changed only little in both breeds whereas culling reasons have changed over the last two decades, with low production becoming a less important reason for culling and infertility becoming more important for Holstein and Jersey breeds. Implications Due to changes of culling reasons, there could be a change in the meaning of survival over time as well. As a result, genetic correlation with survival and other traits might be changed and accuracy and bias of genetic evaluations could be affected.
Feed additives as a strategic approach to reduce enteric methane production in cattle: modes of action, effectiveness and safety
Authors: Honan M. , Feng X. , Tricarico J.M. , Kebreab E.
Published: February 2021

Increasing consumer concern in greenhouse-gas (GHG) contributions from cattle is pushing the livestock industry to continue to improve their sustainability goals. As populations increase, particularly in low-income countries, the demand for animal-sourced foods will place further pressure to reduce emission intensity. Enteric methane (CH4) production contributes to most of the GHG from livestock; therefore, it is key to mitigating such emissions. Feed additives have primarily been used to increase animal productivity, but advances in understanding the rumen has resulted in their development to mitigate CH4 emissions. The present study reviewed some of the main feed additives with a potential to reduce enteric CH4 emissions, focusing on in vivo studies. Feed additives work by either inhibiting methanogenesis or modifying the rumen environment, such that CH4 production (g/day) is reduced. Feed additives that inhibit methanogenesis or compete with substrate for methanogens include 3-nitroxypropanol (3NOP), nitrates, and halogenated compounds containing organisms such as macroalgae. Although 3NOP and macroalgae affect methyl–coenzyme M reductase enzyme that is necessary in CH4 biosynthesis, the former is more specific to methanogens. In contrast, nitrates reduce CH4 emissions by competing with methanogens for hydrogen. However, nitrite could accumulate in blood and be toxic to ruminants. Rumen modifiers do not act directly on methanogens but rather on the conditions that promote methanogenesis. These feed additives include lipids, plant secondary compounds and essential oils. The efficacy of lipids has been studied extensively, and although supplementation with medium-chain and polyunsaturated fatty acids has shown substantial reduction in enteric CH4 production, the results have been variable. Similarly, secondary plant compounds and essential oils have shown inconsistent results, ranging from substantial reduction to modest increase in enteric CH4 emissions. Due to continued interest in this area, research is expected to accelerate in developing feed additives that can provide options in mitigating enteric CH4 emissions.
The mutational load in natural populations is significantly affected by high primary rates of retroposition
Authors: Zhang Wenyu , Xie Chen , Ullrich Kristian , Zhang Yong E. , Tautz Diethard
Published: February 2021

Significance

The phenomenon of retroposition (the reintegration of reverse-transcribed RNA into the genome) has been well studied in comparisons between species and has been identified as a source of evolutionary innovation. However, less attention has been paid to possible negative effects of retroposition. To trace the evolutionary dynamics of these negative effects, our study uses a unique genomic dataset of house mouse populations. It reveals that the initial retroposition rate is very high and that most of these newly transposed retrocopies have a deleterious impact, apparently through modifying the expression of their parental genes. In humans, this effect is expected to cause disease alleles, and we propose that genetic screening should include the search for newly transposed retrocopies.
Retinal bioavailability and functional effects of a synthetic very-long-chain polyunsaturated fatty acid in mice
Authors: Gorusupudi Aruna , Rallabandi Rameshu , Li Binxing , Arunkumar Ranganathan , Blount J. David , Rognon Gregory T. , Chang Fu-Yen , Wade Alexander , Lucas Steven , Conboy John C. , Rainier Jon D. , Bernstein Paul S.
Published: February 2021

Significance

Very-long-chain polyunsaturated fatty acids (VLC-PUFAs) longer than 26 carbons are not present in normal vertebrate diets, yet they are uniquely found in the retina and a few other tissues, implying physiological importance of their biosynthesis from shorter-chain dietary precursors via the action of the ELOVL4 enzyme. While progress has been made by studying retinal samples from human donors and by investigating mouse models of Elovl4 dysfunction, further physiology and interventional research has been hampered by the scarcity of pure VLC-PUFAs. Here, we report the synthesis of a VLC-PUFA (32:6 n-3) in sufficient quantity to study its bioavailability in mice and to investigate its potential roles in normal retinal function and for treatment of disorders associated with VLC-PUFA deficiencies.
Observing ozone chemistry in an occupied residence
Authors: Liu Yingjun , Misztal Pawel K. , Arata Caleb , Weschler Charles J. , Nazaroff William W , Goldstein Allen H.
Published: February 2021

Significance

It has been suggested that indoor exposure to ozone oxidation products contributes materially to the apparent associations between outdoor ozone concentration and morbidity and mortality. Our current understanding of indoor ozone chemistry derives mainly from studies with test surfaces under controlled conditions. Little is known about the overall impact of ozone chemistry on air composition in dynamically changing indoor residential environments. The results presented here reflect a quantitative characterization of overall indoor ozone chemistry in a normally occupied home. Findings reveal a strong influence of off-body skin lipids on indoor ozone chemistry. Being able to elucidate indoor air pollutants derived from ozone chemistry facilitates the investigation of causal links between outdoor ozone concentrations and adverse health effects.
Enhancement and maximum in the isobaric specific-heat capacity measurements of deeply supercooled water using ultrafast calorimetry
Authors: Pathak Harshad , Späh Alexander , Esmaeildoost Niloofar , Sellberg Jonas A. , Kim Kyung Hwan , Perakis Fivos , Amann-Winkel Katrin , Ladd-Parada Marjorie , Koliyadu Jayanath , Lane Thomas J. , Yang Cheolhee , Lemke Henrik Till , Oggenfuss Alexander Roland , Johnson Philip J. M. , Deng Yunpei , Zerdane Serhane , Mankowsky Roman , Beaud Paul , Nilsson Anders
Published: February 2021

Significance

The importance of molecular understanding of the structure, dynamics. and properties of liquid water is recognized in many scientific disciplines. Here, we study experimentally the structure and thermodynamics of bulk liquid water as it is supercooled by evaporation down to ∼228 K. The unique aspect of this work is the use of ultrafast calorimetry that enables us to determine the specific-heat capacity of water to unprecedentedly low temperatures. The observed maximum of about 218 J/mol/K at 229 K is consistent with the liquid–liquid critical point model and supports a proposed fragile-to-strong transition at ∼220 K to explain the steep decrease in the estimated self-diffusion coefficient below 235 K.
Structure of the SARS-CoV-2 RNA-dependent RNA polymerase in the presence of favipiravir-RTP
Authors: Naydenova Katerina , Muir Kyle W. , Wu Long-Fei , Zhang Ziguo , Coscia Francesca , Peet Mathew J. , Castro-Hartmann Pablo , Qian Pu , Sader Kasim , Dent Kyle , Kimanius Dari , Sutherland John D. , Löwe Jan , Barford David , Russo Christopher J.
Published: February 2021

Significance

While the current COVID-19 pandemic continues, the US Food and Drug Administration (FDA) has approved only one drug against the virus—remdesivir. It is a nucleotide analogue inhibitor of the SARS-CoV-2 RNA-dependent RNA polymerase; favipiravir is another member of the same class. These nucleoside analogs were originally developed against other viral polymerases, and can be quickly repurposed against SARS-CoV-2 should they prove efficacious. We used cryoEM to visualize how favipiravir-RTP binds to the replicating SARS-CoV-2 polymerase and determine how it slows RNA replication. This structure explains the mechanism of action, and will help guide the design of more potent drugs targeting SARS-CoV-2.
Cross-talk of insulin-like peptides, juvenile hormone, and 20-hydroxyecdysone in regulation of metabolism in the mosquito
Aedes aegypti
Authors: Ling Lin , Raikhel Alexander S.
Published: February 2021

Significance

In hematophagous female mosquitoes, each reproductive cycle is linked to a separate blood intake, serving as a foundation for the transmission of dangerous human diseases. During each reproductive cycle, female mosquitoes sequentially feed on carbohydrates and protein (blood). Metabolic flux is alternated to support the reproductive cyclicity. We have established that insulin-like peptides (ILPs), critical for regulating metabolism, are genetically controlled by juvenile hormone (JH) and 20-hydroxyecdysone (20E), the key hormones governing the reproduction of female mosquitoes. CRISPR gene-tagging experiments revealed that the JH and 20E pathways coordinate the production of ILPs. This study has uncovered the link between ILPs and JH and 20E pathways in controlling mosquito metabolism during reproduction of the
Aedes aegypti
mosquito.
Language use and identity negotiation in the linguistic landscape
of Chipilo, Mexico
Authors: Sbrighi Lucia
Published: February 2021

This is the first study exploring the
characteristics of the Linguistic Landscape of Chipilo, a town of an
immigrant community of Italian origin in Mexico, which has
maintained its language and ethnic identity over six generations.
The linguistic landscape (hereafter: LL) marks the geographical
space inhabited by Chipileños and reflects the relation among the
languages used (Spanish, Veneto, Italian and English). Its
distinctive trait is the combination of textual items with the
typical sounds, smells and tastes that can be perceived in the
streets of the town. The multisensory LL creates a unique ambience
and contributes to the symbolic construction of a distinct public
space and the promotion of the collective ethnic identity within the
community in relation to other groups.
Ideologies in the linguistic landscape
Authors: Arias Alvarez Alba , Gubitosi Patricia
Published: February 2021

Linguistic Landscape (LL) research is a useful
tool to uncover language ideologies related to the construction of
ethnic identities within a public space. Language in the public
space may reflect the sociopolitical encounters and differences that
exist within a community and need to be contemplated as part of the
larger view of the linguistic behavior of the society. The present
chapter focuses on Puerto Rico, a nation where English and Spanish
signage share the same space and where there is a long-running
discussion on Puerto Rican identity. This chapter aims to examine how
Puerto Ricans living on the island perceive their LL and what the
place of its flag is in the ongoing discussion of identity in the
public arena.
The role of cardiac computed tomography in pre‐participation screening of mature athletes
Authors: Christou Georgios A. , Deligiannis Asterios P. , Kouidi Evangelia J.
Published: February 2021

The overwhelming majority of sports‐related sudden cardiac deaths in mature athletes is attributed to coronary artery disease (CAD). Coronary plaques of mature athletes appear to be more calcified compared to sedentary individuals and thus may be more stable and less likely to be associated with an acute coronary event. Cardiac computed tomography (CT), including unenhanced CT for coronary artery calcium scoring (CACS) and contrast‐enhanced coronary CT angiography, is characterized by very high negative predictive value to rule out CAD. Cardiac CT has been shown to have additional diagnostic value for detection of CAD in athletes over and above exercise electrocardiogram. Moreover, measurement of CACS possibly enables a more precise cardiovascular risk stratification of mature athletes. The main advantage of cardiac CT is its noninvasive nature. Although cardiac CT appears to increase the overall cost of cardiac examinations, this additional cost is much lower than the cost of unnecessary invasive coronary angiographies that would be performed in case of false positive results of exercise electrocardiograms. Radiation exposure may not be a major concern for the application of this modality to pre‐participation screening of athletes, since recent technical advancements have resulted in low radiation dose of cardiac CT.

Highlights

Coronary computed tomography angiography can be used in pre‐participation screening of mature athletes to increase the negative predictive value for excluding coronary artery disease.

The identification of coronary artery calcium score = 0 in an athlete can improve risk stratification, since this athlete can be reasonably managed as an individual with low cardiovascular risk.
Arduino-based STEM education material: work-energy theorem
Authors: Çoban Atakan , Erol Mustafa
Published: February 2021

Twenty first century expertise often requires high-level and cross-disciplinary skills that ought to be a part of todays’ educational activities. Therefore, educational undertakings should be designed in such a way that students can gain the desired expertise and skills. The present work offers an Arduino-based STEM education material, specifically designed to teach the work–energy theorem. The designed physical system is experimentally resolved by directly measuring position-time trajectories which lead to instant velocities. Measured instant position values are employed to determine the amount of work and corresponding velocity values are used to determine the instant kinetic energies of the system. Experimental data, on average, lead to a ratio of

W

Δ

K

=

0.959 which is reasonable concerning the range of experimental error limits therefore smartly validating the work–energy theorem.
Laser cooling and electronic structure studies of CaK and its ions CaK±
Authors: Moussa Amal , El-Kork Nayla , Korek Mahmoud
Published: February 2021

Aiming at a laser cooling investigation, we have used ab initio complete active space self consistent field (CASSCF)/(MRCI +Q) calculations to study the electronic structure of the diatomic molecule CaK and its molecular ions CaK+ and CaK−. The potential energy curves and the static dipole moment curves have been investigated for the considered molecules along with the spectroscopic constants T
e, ω
e, B
e, and R
e, in addition to the values of dipole moment μ
e and dissociation energy D
e. Overall, 19 and 14 electronic states have been studied respectively for CaK, CaK+, from which 12 for CaK and six for CaK+ have been investigated here for the first time. Our obtained results agree well with data related to states that have been previously examined. Nineteen electronic states have been explored for CaK−, which up to our knowledge have not been previously calculated. The transition dipole moments have been calculated for the lowest Σ+–Σ+ and Σ+–Π transitions along with the Franck–Condon factor, Einstein coefficient, the spontaneous radiative lifetime, and the emission oscillator strength corresponding to the investigated transitions. A ro-vibrational analysis has been done via the canonical function approach, where the vibrational parameters E
v, B
v, D
v, and the turning points R
min and R
max have been determined. These calculations showed that the molecule CaK is a suitable candidate for Doppler laser cooling, and we propose a laser cooling scheme to this end. The Doppler limit temperature T
D and recoil temperature T
r have values as low as T
D = 51 μK and T
r = 156 nK. The results should provide a useful reference for experimental spectroscopic and ultra-cold molecular physics studies.
Optical bistability in reflection of the laser pulse in a 1D photonic crystal doped with four-level InGaN/GaN quantum dots
Authors: Shiri Jalil , Khalilzadeh Javad , Asadpour Seyyed Hossein
Published: February 2021

The present study aimed to evaluate the optical properties of 1D photonic crystal (PC) with a defect layer doped by four-level InGaN/GaN quantum dots. Transient and steady-state behavior of the medium completely relies on the intensities and relative phases of coherent coupling fields. In addition, the transient absorption–dispersion spectra of 1DPC can be easily adjusted by choosing the controllable parameters properly. Furthermore, the transmitted and reflected light pulses at

λ
=
1.55
μ
m

(long wavelength) can be tuned by controlling the Rabi frequencies of applied light due to their potential applications in all-optical systems. Furthermore, the effect of relative phase between applied fields on the light propagation was evaluated through the medium. In addition, all-optical switching time was found for subluminal/superluminal and absorption/transmission of light propagation. The required switching time ranges between 2–7 ps. The proposed model may provide some new possibilities for technological applications in optoelectronics and solid-state quantum information science and systems due to large applications in signal processing.
High-efficiency continuous-variable quantum digital signature protocol for signing multi-bit messages
Authors: Zhao Wei , Shi Ronghua , Ruan Xinchao
Published: February 2021

A quantum digital signature (QDS) is guaranteed by the laws of quantum physics and can provide unconditional security to authenticate classical messages. Previous QDS protocols that shared secret keys could be realized using discrete-variable quantum key distribution (DV-QKD), for which the DV-QKD relied on extreme requirements like single-photon detection and extremely weak pulses of light. QDS protocols are mainly focused on how to sign a one-bit message rather than multi-bit messages. In this paper, we present a continuous-variable quantum digital signature (CV-QDS) protocol for signing multi-bit messages. The CV-QDS protocol has better compatibility with existing communication systems and the encoding strategy for multi-bit messages is simpler than before. We hope the continuous-variable protocol could further improve the performance of QDS.
Voltage-dependent plasticity and image Boolean operations realized in a WO
x
-based memristive synapse
Authors: Shi Jiajuan , Lin Ya , Zeng Tao , Wang Zhongqiang , Zhao Xiaoning , Xu Haiyang , Liu Yichun
Published: February 2021

The development of electronic devices that possess the functionality of biological synapses is a crucial step towards neuromorphic computing. In this work, we present a WO
x
-based memristive device that can emulate voltage-dependent synaptic plasticity. By adjusting the amplitude of the applied voltage, we were able to reproduce short-term plasticity (STP) and the transition from STP to long-term potentiation. The stimulation with high intensity induced long-term enhancement of conductance without any decay process, thus representing a permanent memory behavior. Moreover, the image Boolean operations (including intersection, subtraction, and union) were also demonstrated in the memristive synapse array based on the above voltage-dependent plasticity. The experimental achievements of this study provide a new insight into the successful mimicry of essential characteristics of synaptic behaviors.
On the equivalence of self-consistent equations for nonuniform liquids: a unified description of the various modifications
Authors: Frusawa Hiroshi
Published: February 2021

A variety of self-consistent (SC) equations have been proposed for non-uniform states of liquid particles under external fields, including adsorbed states at solid substrates and confined states in pores. External fields represent not only confining geometries but also fixed solutes. We consider SC equations ranging from the modified Poisson–Boltzmann equations for the Coulomb potential to the hydrostatic linear response equation for the equilibrium density distribution of Lennard-Jones fluids. Here, we present a unified equation that explains the apparent diversity of previous forms and proves the equivalence of various SC equations. This unified description of SC equations is obtained from a hybrid method combining the conventional density functional theory and statistical field theory. The Gaussian approximation of density fluctuations around a mean-field distribution is performed based on the developed hybrid framework, allowing us to derive a novel form of the grand-potential density functional that provides the unified SC equation for equilibrium density.
Out-of-equilibrium Frenkel–Kontorova model
Authors: Imparato A
Published: February 2021

A 1D model of interacting particles moving over a periodic substrate and in a position dependent temperature profile is considered. When the substrate and the temperature profile are spatially asymmetric a centre-of-mass velocity develops, corresponding to a directed transport of the chain. This autonomous system can thus transform heath currents into motion. The model parameters can be tuned such that the particles exhibit a crossover from an ordered configuration on the substrate to a disordered one, the maximal motor effect being reached in such a disordered phase. In this case the manybody motor outperforms the single motor system, showing the great importance of collective effects in microscopic thermal devices. Such collective effects represent thus a free resource that can be exploited to enhance the dynamic and thermodynamic performances in microscopic machines.
Support for the personalization of master’s studies based on a fuzzy competency model (on the example of data analysis disciplines)
Authors: Gaibova T V
Published: February 2021

Competence models for evaluating important teaching tools for personalizing educational content. This problem is of particular importance for studying in the master’s program, the teacher of each discipline needs the diversity of the educational trajectories of the master’s students and create an adaptive educational environment for both those who deepen their profiling, continuing their education in the previously chosen direction of training, and for those who have changed the vector of professional development. The aim is to demonstrate a fuzzy model for assessing competence using the example of this organization of training in data analysis. It is developed on the basis of the integration of cognitive modeling and fuzzy logic and is distinguished by the ability to analyze the mutual influence of the concepts of the considered area of knowledge of the target level of learning and is the basis for determining the area of acceptable educational trajectories. The implementation of the proposed model will provide high-quality personalization of semi-structured educational content. The author analyzed the modern skill sets of specialists in the field of data science and analytics, as well as methods and tools for competence assessment in the context of learning adaptation. The requirements for the developed concept of soft learning in the context of personalization of learning in the master’s program are determined, the structure of a fuzzy cognitive map is proposed, which allows one to assess the semi-structured competencies of various groups and determine the priority of mastering the concept of the proposed educational content. The proposed approach will make it possible to systematize the process of identifying permissible educational trajectories at the discipline level, depending on the available knowledge and accumulated professional experience, as well as on the student’s career aspirations, thereby expanding the range of possible educational strategies and increasing the level of organization of the educational process on the part of the teacher and the level of self-organization on the part student.
Methods for implementing the concept of “Smart City” based on Bayesian Intelligent Technologies
Authors: Prokopchina S V
Published: February 2021

Information systems based on Bayesian intelligent technologies make it possible to implement monitoring, control and management tools within the framework of the “Smart City” concept. Such tasks are connected, on the one hand, with the processing of large arrays of various types of information, on the other hand, with difficult conditions for solving problems due to uncertainty. This article discusses the methodological aspects of the application of the regularizing Bayesian approach and Bayesian technologies focused on uncertainty and information processing both in the form of data and in the form of various knowledge. It is shown that such systems can be implemented in the form of intelligent cognitive networks with the processing of different types of measurement, statistical, reporting information, integrated with the assessments and decisions of experts and specialists. Examples of using the proposed approach and technologies for solving applied problems of digitalization of urban economy are given.
Modelling of the stress-strain state of a transport tunnel under load as a measure to reduce operational risks to transportation facilities
Authors: Ivanitskaya N V , Baybulov A K , Safronchuk M V
Published: February 2021

In many countries economic policy has been paying increasing attention to the modernization and development of transport infrastructure as a measure of macroeconomic stimulation.Tunnels as an important component of transport infrastructure save a lot of logistical costs.It stimulates increasing freight and passenger traffic as well as the risks of the consequences of unforeseen overloads.The objective of the paper is to suggest the way to reduce operational risks of unforeseen moving load by modeling of the stress-strain state of a transport tunnel under growing load for different conditions and geophysical parameters.

The article presents the results of a study of the stress-strain state (SSS) of a transport tunnel exposed to a mobile surface load. Numerical experiments carried out in the ANSYS software package made it possible to obtain diagrams showing the distribution of equivalent stresses (von Mises - stresses) according to the finite element model of the tunnel. The research results give grounds to assert that from external factors the stress state of the tunnel is mainly influenced by the distance to the moving load. The results obtained make it possible to predict in advance the parameters of the stress-strain state in the near-contour area of the tunnel and use the results in the subsequent design of underground facilities, as well as to increase their reliability and operational safety.

This investigation gives an opportunity not only to reduce operational risks at the design stage, but to choose an optimal balance between investigation costs and benefits of safety usage period prolongation.
Combining Bayesian and logical-probabilistic approaches for fuzzy inference systems implementation
Authors: Kozhomberdieva G I , Burakov D P
Published: February 2021

In the paper, an original way to implement the fuzzy inference systems is considered. The proposed fuzzy inference model is based on usage of conjunction of probabilistic logic and Bayes’ formula at inference stage. For that preconditions of all the specified fuzzy production rules are transformed to the set of probabilistic functions. As the input probabilities, the values of membership functions of input linguistic variables terms are used. At that given set of production rules is reduced in the way that number of rules will be equal to number of terms of output linguistic variables. For that logic expressions of production preconditions are transformed to orthogonal DNFs. Calculated probability values are used as conditional probabilities in determining the posterior distributions on the set of hypotheses corresponding to values of the output linguistic variables. To determine the posterior probability distribution, we use the formula based on the Bayes’ formula. These posterior distributions are used at defuzzification stage for determining final output variable values, because they are calculated as expected values of corresponding random variables. The program implementation has allowed to estimate the proposed model effectiveness and to compare its results with results of traditionally used Mamdani and Sugeno fuzzy inference algorithms.
Application of Bayesian approach and probability theory for calculating territorial risk and zoning on urban area
Authors: Tunakova Y A , Shagidullin A R , Valiev V S , Galimova A R
Published: February 2021

The article describes a new algorithm for assessing territorial risk. The risk in the algorithm is calculated as the ratio of the prior and posterior probabilities of an unfavorable (risk) event. An event is an excess of the threshold content of toxicants in a certain area of space, taking into account how often this event occurred in all other areas of space. This can be used for zoning an urbanized area. We used a probabilistic safety assessment (PSA) apparatus based on hazard modelling and a scenario-based approach. Such an apparatus does not analyse certain integral characteristics of the process, but all possible states in a given time section at the same time, forming a probabilistic model. The probabilistic approach ensures the accuracy and realism of assessments of the state of the environment of an urbanized area that are unattainable for deterministic methods and, in addition, allows you to take into account the cumulative effect of multiple sources of uncertainty. Using the probabilistic method and assessing the level of risks allows you to broadcast complex scientific information in an accessible format to people making environmental decisions. Risk is not an absolute but a relative category. It is heterogeneous in both time and space. Therefore, it can be used when zoning the environment, especially since the parameters that are used to calculate risk very often form the same data arrays necessary for classifying and zoning spatial non-uniformity of the system in general. After analyzing various approaches, we came to the conclusion that for a given time period the probability of an adverse event will be calculated more accurately if we calculate not using the classical formula (the number of cases per time interval), but in the form of the ratio of the posterior and prior probabilities. This takes into account the risk in a certain area of space and correlates with the frequency of the same event in all other areas. To assess the likelihood of polymetallic pollution of environmental objects in an urbanized area with its subsequent zoning, we considered the variability of the metal content in environmental objects. Based on the probabilities that metal concentrations exceeded their threshold values, the territorial relative risk was calculated and zoning of the urbanized territory was carried out. Testing of the considered approaches was carried out in the territory of Kazan on the basis of an array of data of experimental measurements on the content of metals in environmental objects. For sampling, 170 points were selected across the territory of the city of Kazan, which are under the influence of stationary and mobile sources of the influx of metals into the urbanized territory. The probability distribution of exceeding the threshold level of metal content in environmental objects in the territory of Kazan is shown cartographically.