bluuebunny/crossref_metadata_2025 huggingface dataset:
Wire Myography for Continuous Estimation of the Optimal Concentration of Topical Lidocaine as a Vasodilator in Microsurgery
Authors: Ogawa Haruo , Kusumoto Junya , Nomura Tadashi , Hashikawa Kazunobu , Terashi Hiroto , Sakakibara Shunsuke
Published: January 2021

Background Intraoperative vasospasm during reconstructive microvascular surgery is often unpredictable and may lead to devastating flap loss. Therefore, various vasodilators are used in reconstructive microsurgery to prevent and relieve vasospasm. Lidocaine is a vasodilator commonly used in microvascular surgery. Although many reports have described its in vitro and in vivo concentration-dependent vasodilatory effects, limited studies have examined the pharmacological effects of lidocaine on blood vessels in terms of persistence and titer.

Methods In this study, the vasodilatory effect of lidocaine was examined by using the wire myograph system. Abdominal aortas were harvested from female rats, sliced into rings of 1-mm thickness, and mounted in the wire myograph system. Next, 10, 5, 2, and 1% lidocaine solutions were applied to the artery, and the change in vasodilation force, persistence of the force, and time required to reach equilibrium were measured.

Results The vasodilatory effect was confirmed in all groups following lidocaine treatment. Although strong vasodilation was observed in the 10% lidocaine group, it was accompanied by irreversible degeneration of the artery. Vasodilation in the 1% lidocaine group was weaker than that in the other groups 500 seconds after lidocaine addition (p < 0.05). Between the 5 and 2% lidocaine groups, 5% lidocaine showed a stronger vasodilatory effect 400 to 600 seconds after lidocaine addition (p < 0.01); however, there was no significant difference in these groups after 700 seconds. Additionally, there was no difference in the time required for the relaxation force to reach equilibrium among the 5, 2, and 1% lidocaine groups.

Conclusion Although our study confirmed the dose-dependent vasodilatory effect of lidocaine, 5% lidocaine showed the best vasodilatory effect and continuity with minimal irreversible changes in the arterial tissue.
Laryngeal Mask Airway for Surfactant Administration Versus Standard Treatment Methods in Preterm Neonates with Respiratory Distress Syndrome: A Systematic Review and Meta-analysis
Authors: Al Ali Roqaia Ayesh , Gautam Bishal , Miller Michael R. , Coulson Sherry , Yuen Doris
Published: January 2021

Objective Laryngeal mask airway (LMA) has emerged as an alternative surfactant delivery method. The effectiveness of this method for the delivery of surfactant is uncertain. A meta-analysis of randomized control trials (RCTs) comparing LMA with standard methods of surfactant delivery for the outcomes of surfactant dose repetition, oxygen requirement, mechanical ventilation, intubation, mortality, bronchopulmonary dysplasia (BPD), and pneumothorax.

Study Design Systematic review and meta-analysis of RCTs. Homogeneity between studies was analyzed by using I2 statistics. Risk ratio or mean difference of outcomes was assessed from random effects models. Subgroup analyses were conducted when necessary. Data sources are as follows: Ovid Medline, Embase, and the Cochrane Central Register of Controlled trials from inception till December 2018, bibliographies of identified reviews and trial registries for ongoing studies. RCTs comparing short-term respiratory outcomes in neonates with respiratory distress syndrome who were administered surfactant through an LMA versus standard method of care.

Results Six RCTs were identified, enrolling a total of 357 infants. Administering surfactant via LMA was associated with decreased FiO2 requirement (mean difference = 1.82 (95% confidence interval [CI]: −6.01–9.66), decreased intubation (risk ratio [RR] = 0.17; 95% CI: 0.05–0.57), and decreased mechanical ventilation (RR = 0.44; 95% CI: 0.31–0.61). There were no significant differences between groups for death, BPD, or pneumothorax.

Conclusion LMA might be an effective alternative method of surfactant delivery; however, further high-quality RCTs with larger sample size and including extreme preterm infants are needed to establish LMA as an alternative technique for surfactant delivery.

Key Points
Priorities for social science and humanities research on the challenges of moving beyond animal-based food systems
Authors: Morris Carol , Kaljonen Minna , Aavik Kadri , Balázs Bálint , Cole Matthew , Coles Ben , Efstathiou Sophia , Fallon Tracey , Foden Mike , Giraud Eva Haifa , Goodman Mike , Kershaw Eleanor Hadley , Helliwell Richard , Hobson-West Pru , Häyry Matti , Jallinoja Piia , Jones Mat , Kaarlenkaski Taija , Laihonen Maarit , Lähteenmäki-Uutela Anu , Kupsala Saara , Lonkila Annika , Martens Lydia , McGlacken Renelle , Mylan Josephine , Niva Mari , Roe Emma , Twine Richard , Vinnari Markus , White Richard
Published: February 2021

Increasingly high-profile research is being undertaken into the socio-environmental challenges associated with the over-production and consumption of food from animals. Transforming food systems to mitigate climate change and hidden hunger, ensure food security and good health all point to reducing animal-based foods as a key lever. Moving beyond animal-based food systems is a societal grand challenge requiring coordinated international research by the social sciences and humanities. A ‘selective openness’ to this range of disciplines has been observed within multi-discipline research programmes designed to address societal grand challenges including those concerned with the sustainability of food systems, inhibiting the impact of social sciences and humanities. Further, existing research on animal-based foods within these disciplines is largely dispersed and focused on particular parts of food systems. Inspired by the ‘Sutherland Method’ this paper discusses the results of an iterative research prioritisation process carried out to enhance capacity, mutual understanding and impact amongst European social sciences and humanities researchers. The process produced 15 research questions from an initial list of 100 and classified under the following five themes: (1) debating and visioning food from animals; (2) transforming agricultural spaces; (3) framing animals as food; (4) eating practices and identities; and (5) governing transitions beyond animal-based food systems. These themes provide an important means of making connections between research questions that invite and steer research on key challenges in moving beyond animal-based food systems. The themes also propose loci for future transdisciplinary research programmes that join researchers from the natural sciences, social sciences, and humanities and stakeholders from beyond academia to develop cooperative research and implementation initiatives. The experiences gained from the prioritisation process draw attention to the value of spending time to discuss and collaboratively steer research enquiry into emergent and controversial matters of concern. Fundamental, ethical questions around the continuation or complete cessation of the use of animals for food was a key tension. The positioning of research towards these questions affects not only the framing of the research area but also the partners with whom the research can be carried out and for whom it may be of benefit.
Resolution and the detection of cultural dispersals: development and application of spatiotemporal methods in Lowland South America
Authors: Riris Philip , Silva Fabio
Published: February 2021

Inferring episodes of expansion, admixture, diffusion, and/or migration in prehistory is undergoing a resurgence in macro-scale archaeological interpretation. In parallel to this renewed popularity, access to computational tools among archaeologists has seen the use of aggregated radiocarbon datasets for the study of dispersals also increasing. This paper advocates for developing reflexive practice in the application of radiocarbon dates to prehistoric dispersals, by reflecting on the qualities of the underlying data, particularly chronometric uncertainty, and framing dispersals explicitly in terms of hypothesis testing. This paper draws on cultural expansions within South America and employs two emblematic examples, the Arauquinoid and Tupiguarani traditions, to develop an analytical solution that not only incorporates chronometric uncertainty in bivariate regression but, importantly, tests whether the datasets provide statistically significant evidence for a dispersal process. The analysis, which the paper provides the means to replicate, identifies fundamental issues with resolution and data quality that impede identification of pre-Columbian cultural dispersals through simple spatial gradients of radiocarbon data. The results suggest that reflexivity must be fed back into theoretical frameworks of prehistoric mobility for the study of dispersals, in turn informing the construction of more critical statistical null models, and alternative models of cultural expansion should be formally considered alongside demographic models.
People’s responses to the COVID-19 pandemic during its early stages and factors affecting those responses
Authors: Zhang Junyi
Published: February 2021

The world has suffered from the COVID-19 pandemic. While it is expected that societies will learn lessons from this experience, knowledge about how people responded to the pandemic in its early stages is very limited. With the aim of urgently providing policymakers with scientific evidence about how to better inform the public about fighting against COVID-19, this study made an initial attempt to assess how people responded to the COVID-19 outbreak during its early stages. Based on a life-oriented approach, this study collected data on a large set of behaviors and attitudes through a nationwide retrospective panel survey conducted in Japan at the end of March 2020, when the country had 1953 confirmed infection cases in total. Valid data were collected from 1052 residents from the whole of Japan, taking into account a balanced population distribution in terms of age, gender, and region. Respondents were asked to report changes in their daily activity-travel behavior, long-distance trips, and other life activities caused by the COVID-19 pandemic and associated factors (information reliability, risk perception, attitudes about policy-making and communications with the public, etc.). Results of both aggregate and modeling analyses (using a structural equation model and a data mining approach) indicate that poor communication with the public may have been closely related to the spread of COVID-19 in Japan, and that effective interventions should be made by focusing on interactions between target persons and close members of their social networks. It is also revealed that differentiated communications are necessary to encourage different types of behavioral changes. Risk communication should be better designed to encourage people to voluntarily modify their needs in life [L] and perform the needed activities [A] at places with sufficient spaces [S] and proper duration of time and at the proper timing [TING]. Such a LASTING approach may be crucial to enhance the effects of massive public involvement in mitigating the spread of COVID-19. The findings from this study are not only useful to tackle the current pandemic, but also have a long-term value for addressing future pandemics.
Cellular automata dynamics of nonlinear optical processes in a phase-change material
Authors: Zhang Liwei , Waters Robin F. , MacDonald Kevin F. , Zheludev Nikolay I.
Published: February 2021

Changes in the arrangement of atoms in matter, known as structural phase transitions or phase changes, offer a remarkable range of opportunities in photonics. They are exploited in optical data storage and laser-based manufacturing, and have been explored as underpinning mechanisms for controlling laser dynamics, optical and plasmonic modulation, and low-energy switching in single nanoparticle devices and metamaterials. Comprehensive modeling of phase-change processes in photonics is, however, extremely challenging as it involves a number of entangled processes including atomic/molecular structural change, domain and crystallization dynamics, change of optical properties in inhomogeneous composite media, and the transport and dissipation of heat and light, which happen on time and length scales spanning several orders of magnitude. Here, for the first time, we show that the description of such complex nonlinear optical processes in phase-change materials can be reduced to a cellular automata model. Using the important example of a polymorphic gallium film, we show that a cellular model based on only a few independent and physically-interpretable parameters can reproduce the experimentally measured behaviors of gallium all-optical switches over a wide range of optical excitation regimes. The cellular automata methodology has considerable heuristic value for the study of complex nonlinear optical processes without the need to understand details of atomic dynamics, band structure, and energy conservation at the nanoscale.
Electrical properties of yttrium gate hydrogen-terminated diamond field effect transistor with Al2O3 dielectric layer
Authors: Zhang Minghui , Wang Wei , Chen Genqiang , Abbasi Haris Naeem , Lin Fang , Wen Feng , Wang Kaiyue , Zhang Jingwen , Bu Renan , Wang Hongxing
Published: February 2021

This is the attempt to apply yttrium (Y) gate material to hydrogen-terminated (H-terminated) diamond field effect transistor (FET) with a 10 nm Al2O3 dielectric layer. The maximum drain source current of Y/Al2O3/H-terminated diamond FET with a gate length of 8 μm is −53.9 mA/mm obtained at a gate voltage of −7 V and a drain source voltage of −20 V, and its current on–off ratio exceeds 109, which is large enough for practical applications. Based on the relationship between gate voltage and drain source current, the subthreshold swing is extracted to be 198 mV/dec. The electrical performance reveals that Y/Al2O3/H-terminated diamond FET would pave the way for the development of H-terminated diamond FET.
Detection of partially coherent polarization singular vector beams using Stokes polarimetry
Authors: Khan Saba N. , Joshi Stuti , Kanseri Bhaskar , Senthilkumaran P.
Published: February 2021

We have demonstrated, theoretically and experimentally, a method based on Stokes polarimetry to detect the polarization singularity index (PSI) and the state-of-polarization (SOP) distribution of a partially coherent polarization singular vector beam. It is observed that on reducing the spatial correlation in polarization singular vector beams, the information of the phase vortex and polarization vortex is lost, yielding identical intensity profiles tending toward Gaussian distribution. However, the residual correlated field that comprises the polarized part of irradiance distribution still preserves these vortex structures. The PSI of a partially coherent vector beam can be readily obtained from the flower patterned image of the Stokes parameter's distribution. A uniform deterioration in the magnitude of Stokes intensity all across the beam cross section is observed as a signature of reduced two-point correlation. The respective Stokes phase maps are also invariant and can be used to determine the SOP distribution. The present study foresees potential application in free-space optical communication, optical trapping, and imaging, where the coherence properties of the polarization singular vector beams are of considerable importance.
Voltage-controlled spin–orbit torque switching in W/CoFeB/MgO
Authors: Xu Jinsong , Chien C. L.
Published: February 2021

Voltage control of magnetism and spintronics have been highly desirable but rarely realized. In this work, we show voltage-controlled spin–orbit torque (SOT) switching in W/CoFeB/MgO films with perpendicular magnetic anisotropy (PMA) with voltage administered through SrTiO3 with a high dielectric constant. We show that a DC voltage can significantly lower PMA by 45%, reduce switching current by 23%, and increase the damping-like torque as revealed by the first- and second-harmonic measurements. These are characteristics that are prerequisites for voltage-controlled and voltage-select SOT switching spintronic devices.
Improved short channel electrostatics through design of partially junction-less double-gate MOSFETs
Authors: Kansal Harshit , Medury Aditya Sankar
Published: February 2021

Quantum confinement effects tend to diminish gate control over the channel, further degrading the channel electrostatics of short channel Double-Gate (DG) Silicon-on-Insulator (SOI) MOSFETs. In this work, we first design an n-channel Junction-less (JL) DG MOSFET with a channel length (Lg) of 10 nm, where the source/drain doping, determined through Technology Computer-Aided Design (TCAD) simulations, enables better gate control for different channel thicknesses (tch) and oxide thicknesses (tox). The source/drain doping, thus determined, enables JL DG MOSFETs to overcome quantum confinement effects while also achieving key ITRS (International Technology Roadmap for Semiconductors) targets in terms of sub-threshold slope (S) and threshold voltage (Vth). We then introduce a heavily doped symmetric p-type silicon layer at the interface of the channel region with the top/bottom oxide such that the thickness and doping of the p-type layer enable tuning of the threshold voltage. In this partially JL DG MOSFET, by replacing the n-type doped silicon with n-type silicon–germanium (Si0.7Ge0.3) of lower doping, determined through TCAD simulations, we continue to demonstrate excellent channel electrostatics (ITRS targets) at short channel lengths (Lg = 10 nm) over a wide range of channel and oxide thicknesses while also showing enhanced strong inversion channel currents.
Tunable spin–orbit torques and perpendicular magnetic anisotropy at oxidized Al/Co interfaces
Authors: Musha Akira , Soya Nozomi , Gao Tenghua , Harumoto Takashi , Ando Kazuya
Published: February 2021

We investigated the correlation between perpendicular magnetic anisotropy (PMA) and spin–orbit torques (SOTs) originating at oxidized Al/Co interfaces with various interfacial oxidation levels. We found that both interfacial PMA and interfacial SOTs are maximized by tuning the interfacial oxidation level. The observed tunability of the interfacial PMA is consistent with previous reports, where the origin of the maximization is attributed to the appearance of the electronic hybridization between the O orbitals and Co orbitals in combination with the spin–orbit coupling. The tunable interfacial PMA and interfacial SOT are found to be positively correlated, which suggests that the underlying mechanism behind the interfacial PMA also plays an essential role in the generation of the interfacial SOT.
Multiseriate cortical sclerenchyma enhance root penetration in compacted soils
Authors: Schneider Hannah M. , Strock Christopher F. , Hanlon Meredith T. , Vanhees Dorien J. , Perkins Alden C. , Ajmera Ishan B. , Sidhu Jagdeep Singh , Mooney Sacha J. , Brown Kathleen M. , Lynch Jonathan P.
Published: February 2021

Significance

Multiseriate cortical sclerenchyma (MCS) is a root anatomical phenotype with utility in environments with mechanical impedance. The MCS phenotype is characterized by small cells with thick walls in outer cortical tissue. Genotypes with MCS were associated with greater root lignin concentration, greater tensile strength, and greater root tip bending force compared to non-MCS genotypes. MCS improved root depth and plant growth under mechanical impedance in the greenhouse and field. MCS is heritable and genetically controlled. The identification of anatomical phenes and their genetic control may be an important consideration for breeders for the improvement of crop cultivars with enhanced edaphic stress tolerance.
Strain-tunable electronic and optical properties of h-BN/BC3 heterostructure with enhanced electron mobility*
Authors: Jiao Zhao-Yong , Wang Yi-Ran , Guo Yong-Liang , Ma Shu-Hong
Published: February 2021

By using first-principles calculation, we study the properties of h-BN/BC3 heterostructure and the effects of external electric fields and strains on its electronic and optical properties. It is found that the semiconducting h-BN/BC3 has good dynamical stability and ultrahigh stiffness, enhanced electron mobility, and well-preserved electronic band structure as the BC3 monolayer. Meanwhile, its electronic band structure is slightly modified by an external electric field. In contrast, applying an external strain can mildly modulate the electronic band structure of h-BN/BC3 and the optical property exhibits an apparent redshift under a compressive strain relative to the pristine one. These findings show that the h-BN/BC3 hybrid can be designed as optoelectronic device with moderately strain-tunable electronic and optical properties.
An invisible DWT watermarking algorithm using noise removal with application to dermoscopic images
Authors: Moldovanu S , (Damian) Michis F A , Moraru L
Published: February 2021

A new approach for the digital watermarking process is proposed to be part of the pre-processing stage of a computer-aided diagnosis system. We propose to embed a denoised image acting as the watermark image in the original host image with the final goal of improving the quality of demoscopic images for further image processing operation related to CAD. The proposed algorithm uses Discrete Wavelet Transform (DWT) corroborated with some basic properties of Human Visual System such as Contrast Sensitive Function (CSF) and Noise Visibility Function (NVF) with the goal of correlating the texture properties and noise. This approach hides the watermark (i.e. denoised version of the host image) in high-pass subbands that are focused on image features. The main concern is to evaluate the distortion produced to the host image by watermarking and an objective quality measure function, i.e. Weighted Peak Signal-to-Noise Ratio (WPSNR), is used to evaluate the existing differences between the original and watermarked images. The proposed approach is tested using the available skin lesion images from the digital image archive of the Department of Dermatology of the University Medical Center Groningen. The experiment results show the improved performance of the proposed scheme against a 3 × 3 median filtering attack in comparison with the a 5 × 5 median filtering attack.
Magnetic winding – a key to unlocking topological complexity in flux emergence
Authors: MacTaggart D , Prior C
Published: February 2021

Magnetic helicity is an invariant of ideal magnetohydrodynamics (MHD) that encodes information on the topology of magnetic field lines. It has long been appreciated that magnetic topology is an important constraint for the evolution of magnetic fields in MHD. In applications to the solar atmosphere, understanding magnetic topology is crucial for following the evolution and eruption of magnetic fields. At present, magnetic helicity flux can be measured in solar observations but the interpretation of results is difficult due to the combination of confounding factors. We propose that a renormalization of helicity flux, the magnetic winding, can be used to detect more detailed topological features in magnetic fields and thus provide a more reliable signature for predicting the onset of solar eruptions.
Teleparallel gravity with non-minimally coupled f-essence via Noether symmetry approach
Authors: Myrzakulov Kairat , Kenzhalin Duman , Myrzakulov Nurgissa
Published: February 2021

In this paper, we examine teleparallel gravity with non-minimally coupled with non-canonical fermionic fields (f-essence). Noether symmetry approach can be used to fix the forms of coupling F (Ψ) and the potential V (Ψ) functions of the fermionic fields. In the context of the Friedman-Robertson-Walker metric, we investigate cosmological solutions of the field equations using these forms obtained by the existent of Noether symmetry.
Simple math model for calculation about possibility to disclose Stealth
Authors: Jinghui Qui , Li Hongmei , Wu Chao , Wang Dajing , Denisov O.
Published: February 2021

Stealth coating is the antidote against of the radar. But it can be disclosed by the microwave radiometer because their job based on the measuring the radio-brightness contrast between Stealth object and the background of the environments (sky is cold, Earth is warm).

This short report presents some math model for the simplest calculation of the possible disclosing distance till the Stealth object.
Multiphysic Simulation of molten pool transients for electron beam welding and additive manufacturing processes investigation
Authors: Shcherbakov A V , Gaponova D A , Sliva A P , Goncharov A L , Gudenko A V , Rodyakina R V , Kostin V A , Dragunov V K
Published: February 2021

Molten pool free surface shape calculation and its evaluation in time for analysis of electron beam melting and welding processes is a very important problem. Unfortunately, experimental methods can provide only a part of the necessary information. Electron beam heating creates the conditions for intense metal transfer, and pool surface shape affects the energy absorption efficiency. This paper reports the method which combines the Monte-Carlo simulation for spatial and energy parameters of heating source calculating with the Volume of Fluid algorithm for liquid free-surface numerical evaluation. The velocity and pressure field technique calculation in a molten pool with the action of surface tension forces and vapor recoil pressure is described. It is shown that the proposed simulation method allows to study heat and mass transfer transient processes, including deep penetration channel formation. Model validation was carried out. Simulation results are shown to be consistent with experimental data obtained using a high-speed camera.
Fluid flow structures in an evaporating sessile droplet depending on the droplet size and properties of liquid and substrate
Authors: Turchaninova M.N. , Melnikova E.S. , Gavrilina A.A. , Barash L.Yu.
Published: February 2021

We investigate numerically quasi-steady internal flows in an axially symmetrical evaporating sessile droplet depending on the ratio of substrate to fluid thermal conductivities, fluid volatility, contact angle and droplet size. Temperature distributions and vortex structures are obtained for droplets of 1-hexanol, 1-butanol and ethanol. To this purpose, the hydrodynamics of an evaporating sessile drop, effects of the thermal conduction in the droplet and substrate and diffusion of vapor in air have been jointly taken into account. The equations have been solved by finite element method using ANSYS Fluent. The phase diagrams demonstrating the number and orientation of the vortices as functions of the contact angle and the ratio of substrate to fluid thermal conductivities, are obtained and analyzed for various values of parameters. In particular, influence of gravity on the droplet shape and the effect of droplet size have been considered. We have found that the phase diagrams of highly volatile droplets do not contain a subregion corresponding to a reversed single vortex, and their single-vortex subregion becomes more complex. The phase diagrams for droplets of larger size do not contian subregions corresponding to a regular single vortex and to three vortices. We demonstrate how the single-vortex subregion disappears with a gradual increase of the droplet size.
Calculation of a confidence interval of semantic distance estimates obtained using a large diachronic corpus
Authors: Bochkarev Vladimir V. , Shevlyakova Anna V.
Published: February 2021

Several methods for detection changes in words semantics and appearance of new word meanings have been suggested. These methods use different techniques of estimating semantic distance between words. They are based both on neural network vector models and on simpler vector representations that use frequencies of n-grams including the studied words. This paper proposes a method for calculation the confidence interval of the semantic distance estimations obtained based on the frequency data of n-grams extracted from the large diachronic corpus. This task is complicated because the question about the law of distribution of frequency fluctuations of words and n-grams, despite a number of studies, remains open. The confidence intervals are calculated by statistic modeling using random permutations of n-gram frequencies. To test the proposed method, estimation of semantic distance between two Russian synonyms is used as an example.
Langevin simulations of protoplasmic streaming in non-Euclidean geometry
Authors: Noro Shuta , Okumura Masahiko , Hongo Satoshi , Nagahiro Shinichiro , Ikai Toshiyuki , Nakayama Madoka , Koibuchi Hiroshi
Published: February 2021

The protoplasmic streaming in plant cells enables the transportation of biological materials. This circular flow was experimentally observed with laser Doppler velocimetry, and it was reported that there are two peaks in the velocity distribution. Recently, we reported that these peaks are numerically reproduced by the stochastic or Langevin Navier-Stokes (N-S) simulation technique. However, interactions between fluid and the biological materials have not yet been implemented. In this report, we show that this complex interaction can be simulated in the N-S equation with the Finsler geometry (FG) modeling technique by including an internal directional degree of freedom σ (∈
S
1: circle) corresponding to the small biological materials. We find that the interaction effectively makes the viscosity coefficient small when the variable σ is uniformly aligned.
Investigation of domain structure in ferroelectric thin films by means of the Ising model
Authors: Menshikov E V , Maksimova O G , Osipov S V , Maksimov A V
Published: February 2021

The domain structure in thin ferroelectric films was investigated in the framework of the modified Ising model with short-range exchange and long-range dipole-dipole interactions. The depolarizing field was also taken into account for the study of size effects in thin films. This field is the dominant factor influencing on the existence of phase transitions in the films. We used Monte Carlo method with the standard Metropolis algorithm to generate configurations on three-dimensional cubic lattices. The domains sizes were calculated in the longitudinal and transverse directions relatively to the spontaneous polarization direction. Temperature dependences of the domain sizes are obtained for different values of interaction constants. It was proved that the introduction of the depolarizing field leads to the appearance of a dead layer on the film boundaries. The dead layer thickness increases with increasing temperature. At a certain temperature (not equal to the Curie temperature), the dead layer is destroyed. The temperature dependences of the dielectric susceptibility at different film thicknesses have been calculated. It was shown that these dependencies have two maxima. The first maximum corresponds to a phase transition, the second one exists only for only thin films and corresponds to the destruction of the dead layer.
Monte Carlo Entropic sampling algorithm applied to 3D spin crossover nanoparticles: role of the environment on the thermal hysteresis
Authors: Linares J. , Cazelles C. , Gaci S. , Dahoo P. R. , Boukheddaden K.
Published: February 2021

This contribution deals with the development of a 3D Monte Carlo (MC) entropic sampling algorithm to evaluate the density of states of a SCO nanoparticles using three parameters related to the “magnetization”, the “spin-spin correlation” and the number of molecules at the surface. This information is then used to analyze the role of the interaction parameter, L, between the external environment of the nanoparticle and the surface’s molecules. We show that increasing “L” shifts downward the system’s transition temperature, generating a thermal hysteresis whose width increases linearly with the strength of this parameter “L”. These behaviors are also studied as function of the SCO nanoparticle size.
On Some Fullerenes with Cubic symmetry
Authors: Sánchez-Bernabe Francisco J. , Del Rosario Escalona-Magdaleno M.
Published: February 2021

We consider several fullerenes with cubic symmetry, this means that the graph associated with the fullerene has six faces and eight vertices. One of them is C24 with octagonal faces and triangular vertex. Then, fullerene C32 has a more elaborated structure, because is formed by six squares, and twelve hexagons. The next fullerene that we review is C48 which is formed by six octagons, eight hexagons, and twelve squares. The three previous fullerenes are well known. Our following fullerene is C80 with six faces integrated by four heptagons, and one centred square. Then, we present C128 with six faces formed by five hexagons, and two heptagons, with vertex formed by three pentagons, each of them. Furthermore, we consider the classical fullerene C152 with six faces integrated by six hexagons with one centred hexagon. Finally, we present C164 which is formed by pentagons, hexagons, and heptagons.
Space-time breather solution for nonlinear Klein-Gordon equations
Authors: Takei Yasuhiro , Iwata Yoritaka
Published: February 2021

Klein-Gordon equations describe the dynamics of waves/particles in sub-atomic scales. For nonlinear Klein-Gordon equations, their breather solutions are usually known as time periodic solutions with the vanishing spatial-boundary condition. The existence of breather solution is known for the Sine-Gordon equations, while the Sine-Gordon equations are also known as the soliton equation. The breather solutions is a certain kind of time periodic solutions that are not only play an essential role in the bridging path to the chaotic dynamics, but provide multi-dimensional closed loops inside phase space. In this paper, based on the high-precision numerical scheme, the appearance of breather mode is studied for nonlinear Klein-Gordon equations with periodic boundary condition. The spatial periodic boundary condition is imposed, so that the breathing-type solution in our scope is periodic with respect both to time and space. In conclusion, the existence condition of space-time periodic solution is presented, and the compact manifolds inside the infinite-dimensional dynamical system is shown. The space-time breather solutions of Klein-Gordon equations can be a fundamental building block for the sub-atomic nonlinear dynamics.
Simulator development of a rotary magnetocaloric refrigerator by stepwise regenerator modelling approach
Authors: Câmara L D T , Tedesco J C G
Published: February 2021

Magnetic refrigeration has been seeing as a promising technology based on the magnetocaloric effect. One of its great advantages is it offers smaller global environmental impact relating to conventional refrigeration. Modeling and simulation of such processes can provide important data in the development and optimization of the experimental devices. Among existing designs, the rotary refrigerators presents several challenges in terms of complexity when comparing to reciprocating ones, which is compensated by several properties. A novel full process simulator of a magnetocaloric refrigerator processes was implemented to study the processes performance over different conditions. A stepwise modeling approach was applied, simplifying the phenomena of heat transfers. Gd was chosen as refrigerant material because of its magnetic transition temperature. The routine considered a rotating clockwise Gd wheel with an anticlockwise closed flow loop of water, which percolates the six Gd porous beds, hot and cold heat exchanger. The simulator was able to represent the transient aspects as well as the steady state conditions of the processes, considering both time performance and numerical stability. The inversion in heat transfer profiles along the process was used as a limit in the calculation of the maximum heat transfer absorption in the cold exchanger.
On dark stars, galactic rotation curves and fast radio bursts
Authors: Nikitin Igor
Published: February 2021

This paper is a continuation of our recent work on Radial Dark Matter stars (RDM-stars), black holes, coupled with radial flows of dark matter. As a galaxy model, it produces flat rotation curves, approximately valid for many galaxies far from the center. In this paper, more detailed modeling is carried out, including the vicinity of the galactic center. Assuming that the distribution of stellar black holes repeats the distribution of luminous matter, we get a perfect match between the model rotation curves and the observed ones. Further, using numerical integration, we examine the gravitational field of an individual RDM-star. The computation shows the event horizon being erased and rapidly increasing mass density arising instead (mass inflation). In this regime, we apply the previously constructed Planck star model, where at high densities a repulsive force occurs (quantum bounce). In our stationary model, the evolution of a Planck star has stopped under the pressure of dark matter flows. This system is considered as a possible source of Fast Radio Bursts (FRBs). In a scenario involving an asteroid falling onto an RDM-star, the model reproduces the correct frequency range of FRBs. Their total energy, coherence and short duration are explained as well.
Mathematical modeling and visualization of topologically non-trivial solutions in general relativity
Authors: Nikitin Igor
Published: February 2021

In general relativity, there is a class of solutions that currently do not have observed analogues, but on which the theory is shaped, giving an understanding what is fundamentally possible within its framework. Such solutions include wormholes, tunnels that connect distant regions in spacetime. Although not a single wormhole has yet been discovered, there is a large number of works devoted to their study, thanks to which wormholes as a class of solutions become firmly established in modern science. In this paper, we consider two topologically nontrivial types of solutions related to wormholes. First: wormholes that can open and close. In this relation, we will discuss topological censorship theorems, which under certain conditions prohibit changing topology. We will also discuss known ways to circumvent these theorems. Using analytical and numerical methods, as well as visualization, we will construct an example of an opening and closing wormhole with the dimensions of the central black hole in the Milky Way galaxy. Our construction continues the work by Kardashev, Novikov and Shatskiy, in which a static wormhole with the same parameters was considered. The second type is a modification of Visser’s dihedral wormhole solution for a dynamic case.
Using Particle Swarm Optimization for design comb compensator with magnitude response synthetized as sine function
Authors: Salguero Luna S , Jovanovic Dolecek G , Fernández De Lara Sosa A
Published: February 2021

Comb compensator improves the passband characteristic of comb filter, i.e. decreases the comb passband droop. This paper presents one method for a comb compensator design with the magnitude response synthetized as sine function. The parameter of design is the amplitude of sine function denoted as A. The goal is to find the amplitude of sine function A for each value of comb parameter, K, K=1, …,5, where K is the number of the cascaded comb filters. First the optimum values of the amplitude of sinusoidal function A, for each value of K, K=1, …,5 are obtained using Particle Swarm Optimization (PSO). It is demonstrated that the obtained values A practically do not depend on the decimation factor M, for M>10. In next step the obtained values of the parameter A are presented as sum of powers of two (SPT) to get a multiplierless design. The method is illustrated with one example and compared with the methods from literature.
Deliberative architecture for smart sensors in the filtering operation of a water purification plant
Authors: Mendoza E. , Andramuño J. , Núñez J. , Benítez I.
Published: February 2021

The increase of applications for industrial smart sensors is booming, mainly due to the use of distributed automation architectures, industrial evolution and recent technological advances, which guide the industry to a greater degree of automation, integration and globalization. In this research work, an architecture for deliberative-type intelligent industrial sensors is proposed, based on the BDI (Belief Desire Intentions) model, adaptable to the measurement of different variables of the filtering process of a water purification plant. An intelligent sensor with functions of signal digitalization, self-calibration, alarm generation, communication with PLC, user interface for parameter adjustment, and analysis with data extrapolation have been arranged. For decision making, the use of fuzzy logic techniques has been considered, which allows imprecise parameters to be appropriately represented, simplifying decision problem solving in the industrial environment, generating stable and fast systems with low processing requirements. The proposed architecture has been modelled, simulated and validated using UML language in conjunction with Petri nets, which facilitate the representation of discrete system events, presenting them clearly and precisely. In the implementation and testing of the prototype, C/C ++ language has been used in an 8-bit microcontroller, experimentally corroborating the operation of the device, which allowed evaluating the behavior of a pseudo-intelligent agent based on the requirements of the water treatment plant, and also through comparisons with similar works developed by other researchers.
Topological climate change with permafrost feedback
Authors: Kypke Kolja L , Langford William F , Nethercott Nathaniel , Willms Allan R
Published: February 2021

Climate models predict that the climate of the Earth is warming and will continue to warm in coming centuries, if there is no mitigation. A recent energy balance model [Kypke et al., Nonlin. Process. Geophys.
27 (2020) 391–409] forecasts that, if the current increase of carbon dioxide in the atmosphere continues unabated, then in the next century the climate of the Earth will not only get warmer, but will transition abruptly via a bifurcation, to a warm equable climate unlike any climate seen on Earth since the Pliocene. This transition to a new climate state is a topological change. That model includes the effects of water vapour feedback and ice albedo feedback, as well as ocean and atmospheric heat transport. This paper adds to that model further amplification by permafrost feedback. That is, as the Arctic warms, permafrost will thaw, releasing large amounts of the greenhouse gases carbon dioxide and methane, which cause further warming. Since knowledge of permafrost stores and release rates is limited, a range of permafrost carbon release sensitivities (Q
10) is considered. The model predicts that permafrost feedback accelerates the timing and increases the likelihood of a topological climate change in the Arctic, and reinforces the view that permafrost feedback should not be ignored in Anthropocene climate models.
The influence of the load’s geometrical characteristics on the generation of the electro-thermo-mechanical instability in a single wire Z-pinch
Authors: Kaselouris E , Tamiolakis G , Dimitriou V , Tatarakis M
Published: February 2021

The Z-pinch plasma device is a type of plasma confinement system that uses electrical current to generate a magnetic field which compresses a current-carrying wire. In a previous proof-of-principle study, we demonstrated that in the interaction of a single wire with a pulsed current, the generated Electro-Thermo-Mechanical (ETM) instability in the solid phase acts as a seeding mechanism for the later developed instabilities observed in the plasma phase. In this study, the influence of the geometrical characteristics, such as length and thickness of the load-wire, on the generation of the ETM instability are investigated. Finite element multiphysics-multiphase simulations starting from the solid state are coupled with Magneto-Hydro-Dynamics (MHD) simulations to study the solid to plasma phase transition and the matter’s dynamics. The numerical results of the wire expansion dynamics prior to plasma formation are validated by experimental results from a modified Fraunhofer diffraction diagnostic, while in the plasma phase the simulated plasma dynamics is validated by shadowgraphic and interferometric experimental results. The numerical and experimental results demonstrate a satisfactory agreement for the wire expansion dynamics and the growth rate of the developed instabilities, for varying wire thickness and length.
Predicting the Behaviour of a Vortex Shedding-Based Passive Mechanical Micro Heat Exchanger
Authors: Granados-Ortiz F-J , Garcia-Cardosa M , Ortega-Casanova J
Published: February 2021

In the recent years, microscale applications are gaining increasing importance. Despite their advances, the technology and resources needed to develop new designs may be a drawback for reduced scale engineering testing. To overcome this, computational methods are an efficient tool to predict how a real-life system may behave prior physical construction. The present work aims to investigate numerically effective models to predict the conditions at which a micro heat exchanger (MHE) is able to promote mixing by vortex shedding mechanics. In spite of vortex-shedding is a well-known mechanism in flow physics, it is not possible to know a priori whether a configuration (for a given geometry and flow velocity) may or may not lead to this desired vortex detachment to enhace mixing. Thus, Machine Learning methods are used for prediction, trained with finite-volume numerical simulations of different MHE devices selected based on their performance. A classification model is used to predict which configurations lead to vortex shedding. Also, a correlation regression model is developed to predict the critical Reynolds number. When the critical Reynolds number is surpassed for a given geometry, vortex shedding appears and its intensity controls the thermal mixing efficiency of the microdevice. These predictors could be useful in the search of optimal configurations by optimisation algorithms, since in the sampling process could be used to define constrains.
Simulation of Time-Lapse Resistivity Logging During Two-Phase Well Testing in Petroleum Reservoirs
Authors: Shishkina O A , Indrupskiy I M , Kovalenko K V , Makarova A A , Zakirov E S , Anikeev D P , Anikeeva E S
Published: February 2021

Well testing methods are widely used in petroleum industry to identify reservoir parameters in-situ, at real reservoir flow conditions. Two-phase tests with water injection extend capabilities of well testing to evaluation of oil-water flow characteristics through the solution of an inverse problem based on well measurements during the test. Near-wellbore water saturation is used as one of the informative measured parameters. However, water saturation is actually not directly measured on wells. Instead, it is interpreted from time-lapse well logging data, with resistivity logging being one of the options. This means that forward and inverse problems are to be extended to incorporate direct simulations of resistivity logging. In this paper we address the forward problem. It is formulated and solved for different types of logging tools, both for open hole and through the casing. A numerical algorithm and software implementation have been developed for repeated solution of an axisymmetric forward problem of resistivity logging – a 2D elliptical partial differential equation for electrical potential. Distributions of formation resistivity at the moments of logging are calculated from distributions of water saturation and salinity. The latter are computed through numerical solution of the forward problem of well testing – a two-phase oil-water flow in the reservoir with changing salinity of the water phase, with full account for real fluid and reservoir properties. The software implementation of the resistivity logging problem has been tested in comparison with the known theoretical solutions. Examples are presented to show how time-lapse changes in resistivity logging data reflect the specifics of the two-phase flow with changing water salinity during the well test.