Field Behavior Research Articles

Investigating the magnetic and hysteretic properties of graphyne-based nanostructures: a comparative study of shape effects on critical temperatures, coercivity, and remanence

Our study aims to investigate the physical properties of graphyne-based nanostructures, with a particular focus on their magnetic and hysteretic features. We analyze the influence of shape on these properties in an Ising-type graphyne structure using the effective field theory (EFT) method. Our research focuses on the critical and compensation temperatures, coercivity, and remanence of the graphyne structure in different shapes, ranging from alpha (α) to beta (β) to gamma (γ). We use the magnetization curves and hysteresis loops obtained from central and intermediate spins. We also illustrate the behavior of the coercive field and remanent magnetization as well as hysteresis loop the effect of exchange interactions r and s as well as temperature. We observe N- and R- type compensation in the β graphyne, and L- and S- type compensations in the γ graphyne. We also find that the widest hysteresis is observed in γ graphyne.

Faithful quantum teleportation through common and independent qubit-noise configurations and multi-parameter estimation in the output of teleported state

Quantum teleportation allows the transmission of unknown quantum states over arbitrary distances. This paper studies quantum teleportation via two non-interacting qubits coupled to local fields and Ornstein Uhlenbeck noise. We consider two different qubit-noise configurations, i.e., common qubit-noise interactions and independent qubit-noise interactions. We introduce a Gaussian Ornstein Uhlenbeck process to take into account the noisy effects of the local external fields. Furthermore, we address the intrinsic behavior of classical fields toward single- and two-qubit quantum teleportation as a function of various parameters. Additionally, using a quantum estimation theory, we study single- and multi-parameter estimation of the teleported state output for single and two-qubit quantum teleportation scenarios. One important application of this work is obtaining more valuable information in quantum remote sensing.

A Closer Cooperation between Space and Seismology Communities – a Way to Avoid Errors in Hunting for Earthquake Precursors

The space physicists and the earthquake (EQ) prediction community exploit the same instruments – magnetometers, but for different tasks: space physicists try to comprehend the global electrodynamics of near-Earth space on various time scales, whereas the seismic community develops electromagnetic methods of short-term EQ prediction. The lack of deep collaboration between those communities may result sometimes in erroneous conclusions. In this critical review, we demonstrate some incorrect results caused by a neglect of specifics of geomagnetic field evolution during space weather activation. The considered examples comprise: Magnetic storms as a trigger of EQs; ULF waves as a global EQ precursor; Geomagnetic impulses before seismic shocks; Long-period geomagnetic disturbances generated by strong EQs; Discrimination of underground ULF sources by amplitude-phase gradients; Depression of ULF power as a short-term EQ precursor; and Detection of seimogenic emissions by satellites. To verify the reliability of the above widely disseminated results data from available arrays of fluxgate and search-coil magnetometers have been re-analyzed. In all considered events, the “anomalous” geomagnetic field behavior can be explained by global geomagnetic activity, and it is apparently not associated with seismic activity. This critical review does not claim that ULF electromagnetic field cannot be used as a sensitive indicator of the EQ preparation processes, but we suggest that both communities must cooperate their studies more tightly using data exchange, combined usage of magnetometer networks, organization of CDAW for unique events, etc.

Cell and gene therapy investment: evolution and future outlook on investor perspectives

Background aimsTo better understand the attitudes and behaviors of investors involved in funding cell and gene therapy (CGT) businesses, the Business Development and Finance) subcommittee of International Society for Cell and Gene Therapy, in collaboration with Truist Securities, conducted a broad survey of the investment community in late 2021. MethodsThis survey follows a similar study that this group executed in 2018, and the longitudinal comparisons between the two time periods provide insights into how investor behavior in the CGT field has evolved. ResultsThe vast majority of investor respondents are specialist biotech investors who are primarily active in deploying capital in North America and Europe. There was a notable increase in the proportion of investors actively deploying capital in China and Japan between 2018 and 2021. The percentage of respondents’ portfolios dedicated to CGT companies has also increased in this period, reflecting a noteworthy trend in the therapeutic landscape. ConclusionsClinically significant data remain the dominant force behind investment decisions, whereas competition from other drug modalities has now emerged as the most-cited barrier to making a CGT investment, eclipsing safety concerns as the most significant barrier to investment in 2018. Concerns around manufacturing and scale-up have also increased in prominence amongst the investment community. Gene-editing technologies are attracting investors as the most compelling new CGT technology. This survey also revealed that most investors expect to increase their level of investment in allogeneic technologies relative to autologous products in the coming years.

Spherically symmetric evolution of self-gravitating massive fields

We are interested in the global dynamics of a massive scalar field evolving under its own gravitational field and, in this paper, we study spherically symmetric solutions to Einstein's field equations coupled with a Klein-Gordon equation with quadratic potential. For the initial value problem we establish a global existence theory when initial data are prescribed on a future light cone with vertex at the center of symmetry. A suitably generalized solution in Bondi coordinates is sought which has low regularity and possibly large but finite Bondi mass. A similar result was established first by Christodoulou for massless fields. In order to deal with massive fields, we must overcome several challenges and significantly modify Christodoulou's original method. First of all, we formulate the Einstein-Klein-Gordon system in spherical symmetry as a non-local and nonlinear hyperbolic equation and, by carefully investigating the global dynamical behavior of the massive field, we establish various estimates concerning the Einstein operator, the Hawking mass, and the Bondi mass, including novel positivity and monotonicity properties. Importantly, in addition to a regularization at the center of symmetry we find it necessary to also introduce a regularization at null infinity. We also establish new energy and decay estimates for, both, regularized and generalized solutions.

Efficient AI-Physics hybrid model with productive capabilities to reduce the time of history matching and scenario assessment; a case study: Minagish oil field

This paper proposes a novel approach that combines physics-based numerical simulation with deep-learning neural networks to create an AI-Physics hybrid model for reservoir simulation. Our primary objective is to reduce the time of history match and achieve the best match between model and observation data using our hybrid model. We trained our model using historical data and created a reliable forecasting model that predicts field behavior and proposes new scenarios to improve production in the upcoming years. To test our model, we combined AI physics history training with blind test prediction calculations of the remaining oil map, and the AI physics model created a forecast scenario definition based on this map. Our proposed simulation method can reduce the time of history matching and scenario evaluation by 90-95%. We created three improved forecast scenarios based on predefined scenarios that can produce millions of standard barrels more oil over three years than the original development scenario. The results demonstrate the potential of our AI-Physics hybrid model in revolutionizing reservoir simulation in the oil and gas industry. Our approach can significantly reduce simulation time, improve forecasting accuracy, and optimize production strategies, leading to significant economic benefits.

Reduced-Order Model Approaches for Predicting Airfoil Performance

This study delves into the construction of reduced-order models (ROMs) of a flow field over a NACA 0012 airfoil at a moderate Reynolds number and an angle of attack of 8∘. Numerical simulations were computed through the finite-volume solver OpenFOAM. The analysis considers two different reduction techniques: the standard Galerkin projection method, which involves projecting the governing equations onto proper orthogonal decomposition modes (POD−ROMs), and the cluster-based network model (CNM), a fully data-driven nonlinear approach. An analysis of the topology of the dominant POD modes was conducted, uncovering a traveling wave pattern in the wake dynamics. We compared the performances of both ROM techniques regarding their prediction of flow field behavior and integral quantities. The ROM framework facilitates the practical actuation of control strategies with significantly reduced computational demands compared to the full-order approach.

Transient Response of Macroscopic Deformation of Magnetoactive Elastomeric Cylinders in Uniform Magnetic Fields.

Significant deformations of bodies made from compliant magnetoactive elastomers (MAE) in magnetic fields make these materials promising for applications in magnetically controlled actuators for soft robotics. Reported experimental research in this context was devoted to the behaviour in the quasi-static magnetic field, but the transient dynamics are of great practical importance. This paper presents an experimental study of the transient response of apparent longitudinal and transverse strains of a family of isotropic and anisotropic MAE cylinders with six different aspect ratios in time-varying uniform magnetic fields. The time dependence of the magnetic field has a trapezoidal form, where the rate of both legs is varied between 52 and 757 kA/(s·m) and the maximum magnetic field takes three values between 153 and 505 kA/m. It is proposed to introduce four characteristic times: two for the delay of the transient response during increasing and decreasing magnetic field, as well as two for rise and fall times. To facilitate the comparison between different magnetic field rates, these characteristic times are further normalized on the rise time of the magnetic field ramp. The dependence of the normalized characteristic times on the aspect ratio, the magnetic field slew rate, maximum magnetic field values, initial internal structure (isotropic versus anisotropic specimens) and weight fraction of the soft-magnetic filler are obtained and discussed in detail. The normalized magnetostrictive hysteresis loop is introduced, and used to explain why the normalized delay times vary with changing experimental parameters.

The open field assay is influenced by room temperature and by drugs that affect core body temperature.

The open field assay is used to study anxiety-related traits and anxiolytic drugs in rodents. This assay entails measuring locomotor activity and time spent in the center of a chamber that is maintained at ambient room temperature. However, the ambient temperature in most laboratories varies daily and seasonally and can differ between buildings. We sought to evaluate how varying ambient temperature and core body temperature (CBT) affected open field locomotor activity and center time of male wild-type (WT, C57BL/6) and Transient Receptor Potential Subfamily M Member 8 ( Trpm8) knock-out ( Trpm8 -/- ) mice. TRPM8 is an ion channel that detects cool temperatures and is activated by icilin. Mice were placed in the open field at 4°C and 23°C for 1 hour. Distance traveled and time spent in the center were measured. Mice were injected with icilin, M8-B, diazepam, or saline, and changes in activity level were recorded. The cooling agent icilin increased CBT and profoundly reduced distance traveled and center time of WT mice relative to controls. Likewise, cooling the ambient temperature to 4°C reduced distance traveled and center time of WT mice relative to Trpm8 -/- mice. Conversely, the TRPM8 antagonist (M8-B) reduced CBT and increased distance traveled and center time of WT mice when tested at 4°C. The TRPM8 antagonist (M8-B) had no effect on CBT or open field behavior of Trpm8 -/- mice. The anxiolytic diazepam reduced CBT in WT and Trpm8 -/- mice. When tested at 4°C, diazepam increased distance traveled and center time in WT mice but did not alter open field behavior of Trpm8 -/- mice. Environmental temperature and drugs that affect CBT can influence locomotor behavior and center time in the open field assay, highlighting temperature (ambient and core) as sources of environmental and physiologic variability in this commonly used behavioral assay.

Simplified methodology for fatigue analysis of reinforced asphalt systems

Fatigue analysis has an important role in evaluating the durability and performance of asphalt pavements, especially when novel or alternative materials are used. Numerous laboratory studies have investigated fatigue performance with the aim of estimating field behavior as accurately as feasible. Therefore, there are currently many different test methods and data analysis approaches that can be used. One of the most common laboratory test methods is the four-point bending beam (4PBB) test, which results are usually analyzed using the so-called traditional (where 50% reduction in initial stiffness is considered as failure criterion) or the energy ratio (ER) approach. However, outcomes from previous studies have shown that these approaches may not be appropriate and reliable if geogrids are used as a reinforcement. As a possible solution, this study proposes a new simplified flex point (SFP) approach that considers the flex point of the strain amplitude curve, measured during 4PBB fatigue tests, to calculate the number of cycles to failure. These three approaches were applied to four double-layered asphalt sets: one unreinforced and three reinforced with geogrids of different strength (50 x 50, 100 x 100 and 100 x 200 kN/m). The impact of reinforcement on the fatigue life was evaluated by comparing the critical strain values (ε6) of reinforced and unreinforced sets through the fatigue resistance improvement factor. The research findings showed that the use of geogrids improves fatigue life when the SFP and ER approaches are applied and that the traditional approach might not always be appropriate for assessing the fatigue resistance of reinforced asphalt mixtures.

Multimodal single-neuron, intracranial EEG, and fMRI brain responses during movie watching in human patients

We present a multimodal dataset of intracranial recordings, fMRI, and eye tracking in 20 participants during movie watching. Recordings consist of single neurons, local field potential, and intracranial EEG activity acquired from depth electrodes targeting the amygdala, hippocampus, and medial frontal cortex implanted for monitoring of epileptic seizures. Participants watched an 8-min long excerpt from the video “Bang! You’re Dead” and performed a recognition memory test for movie content. 3 T fMRI activity was recorded prior to surgery in 11 of these participants while performing the same task. This NWB- and BIDS-formatted dataset includes spike times, field potential activity, behavior, eye tracking, electrode locations, demographics, and functional and structural MRI scans. For technical validation, we provide signal quality metrics, assess eye tracking quality, behavior, the tuning of cells and high-frequency broadband power field potentials to familiarity and event boundaries, and show brain-wide inter-subject correlations for fMRI. This dataset will facilitate the investigation of brain activity during movie watching, recognition memory, and the neural basis of the fMRI-BOLD signal.

Waveformer for modeling dynamical systems

Neural operators have gained recognition as potent tools for learning solutions of a family of partial differential equations. The state-of-the-art neural operators excel at approximating the functional relationship between input functions and the solution space, potentially reducing computational costs and enabling real-time applications. However, they often fall short when tackling time-dependent problems, particularly in delivering accurate long-term predictions. In this work, we propose “waveformer”, a novel operator learning approach for learning solutions of dynamical systems. The proposed waveformer exploits wavelet transform to capture the spatial multi-scale behavior of the solution field and transformers for capturing the long horizon dynamics. We present four numerical examples involving Burgers’s equation, KS-equation, Allen–Cahn equation, and Navier–Stokes equation to illustrate the efficacy of the proposed approach. Results obtained indicate the capability of the proposed waveformer in learning the solution operator and show that the proposed Waveformer can learn the solution operator with high accuracy, outperforming existing state-of-the-art operator learning algorithms by up to an order, with its advantage particularly visible in the extrapolation region.

Anomalous features of the geomagnetic field behavior at the end of the Cretaceous normal superchron based on the results of the study of the Turonian–Santonian in the Southwestern Crimea

In 394 samples characterizing 266 stratigraphic levels in four Turonian–Santonian sections in the Southwestern Crimea, characteristic remanent magnetization components (ChRM) formed at the stage of diagenesis is identified. The data obtained represent the record of the Paleocene geomagnetic variations of high amplitude (rms deviation S = 25.9° with a fixed cut-off angle of 45°, which is about twice as high as the model S for this latitude) in the sediments formed in ~5–6 Ma and are interpreted as anomalous behavior of the geomagnetic field in the Turonian, Coniacian, and Santonian.

Synchrony between dipole and quadrupole during magnetic field reversals and excursions

In contrast to reversals, excursions of the geomagnetic field can occur at lower convection intensities in the Earth’s core. Since in such geodynamo regimes the behavior of the magnetic field is still quasi regular, a reduction of the dipole field during an excursion may indicate a global failure of the dynamo process. As a consequence, it is possible that during the excursion, not only the dipole component, but also the higher harmonics of the field decrease. This hypothesis is tested in a three-dimensional (3D) dynamo model.

A proof-of-concept Bitter-like HTS electromagnet fabricated from a silver-infiltrated (RE)BCO ceramic bulk

A novel concept for a compact high-field magnet coil is introduced. This is based on stacking slit annular discs cut from bulk rare-earth barium cuprate ((RE)BCO) ceramic in a Bitter-like architecture. Finite-element modelling shows that a small 20 turn stack (with a total coil volume of < 20 cm3) is capable of generating a central bore magnetic field of > 2 T at 77 K and > 20 T at 30 K. Unlike resistive Bitter magnets, the high-temperature superconducting (HTS) Bitter stack exhibits significant non-linear field behaviour during current ramping, caused by current filling proceeding from the inner radius outwards in each HTS layer. Practical proof-of-concept for this architecture was then demonstrated through fabricating an uninsulated four-turn prototype coil stack and operating this at 77 K. A maximum central field of 0.382 T was measured at 1.2 kA, with an accompanying 6.1 W of internal heat dissipation within the coil. Strong magnetic hysteresis behaviour was observed within the prototype coil, with ≈30% of the maximum central field still remaining trapped 45 min after the current had been removed. The coil was thermally stable during a 15 min hold at 1 kA, and survived thermal cycling to room temperature without noticeable deterioration in performance. A final test-to-destruction of the coil showed that the limiting weak point in the stack was growth-sector boundaries present in the original (RE)BCO bulk.

Unveiling SU(3) flux tubes at nonzero temperature: electric fields and magnetic currents

We report on the results of measuring the chromoelectric fields in a flux tube created by a static quark-antiquark pair in finite-temperature SU(3) gauge theory. Below the deconfinement temperature the field behavior is similar to the zero-temperature case. Above the deconfinement temperature the field shape remains the same, but the field values drop when the distance between the quark and antiquark increases, thus showing the disappearance of the confining potential.

Insight into the dynamics of slip and radiative effect on magnetohydrodynamic flow of hybrid ferroparticles over a porous deformable sheet

AbstractIn the present work, we explored the magnetohydrodynamic boundary layer flow in the presence of pressure gradient across a flat plate. The effects of the slip velocity conditions, thermal Radiation the addition of hybrid Ferroparticles (i.e., a mixture of two types of magnetic nanoparticles for example, (magnetite () and cobalt ferrite ()) in base fluid ( ) and Porous wall (suction/ injection) are also considered in this study. Basic partial differential equations are transformed into nonlinear ordinary differential equations using the appropriate similarity transformations. Then, this equation was treated numerically by using the Runge–Kutta–Fehlberg 4th–5th order method with the shooting technique and analytically via an efficient method called the Generalized Decomposition Method. The effects of various physical parameters on the velocity and temperature profiles are shown graphically. It is found that the incorporation of hybrid nanoparticles demonstrates a relatively substantial impact on the behavior of dynamic and thermal field; outperforming both non‐hybrid nanoparticles and regular fluid in terms of speed and temperature enhancement. The slip and permeability parameters significantly alter the flow structure. The positive values of the slip and permeability parameters enhance the flow velocity and reduce the temperature, leading to the desired flow behavior. Conversely, adopting negative values of these parameters reverses the effect. Furthermore, the radiation parameter enhances the temperature distribution. Additionally, the boundary layer separation tends to disappear with the increase in the magnetic parameter. The results obtained clearly show the accuracy of the proposed method and also indicate an excellent agreement between analytical and numerical data.

The interaction between Pd/CeO2 crystal surface and electric field: Application to complete oxidation of methane

Pd/CeO2 with different crystal faces can significantly affect the methane oxidation process, but the catalytic behavior in electric field is not clear yet. The supported Pd/CeO2 with rod, octahedral and cubic morphologies were synthesized by hydrothermal method, and their methane oxidation efficiency in electric field was measured. The structure of Pd/CeO2 and reaction mechanism in electric field were investigated by XRD, BET, XPS, H2-TPR, TEM and in situ DRIFTs. Studies show that the synergistic effect between electric field and (111) crystal plane in octahedral CeO2 is the strongest and (110) in rod CeO2 is the main active restraint crystal plane. The Pd atoms on the surface of Pd/CeO2-oct are exposed to the most amount of Pd atoms and the main Pd nanoparticles are present. Pd species on CeO2-cube and CeO2-rod surface with relatively low activity exist mainly in the form of Pd2+ and Pd4+, whereas Pd0 and Pd2+ on the Pd/CeO2-oct surface are more favorable for CH4 oxidation in the catalytic cycle. Pd4+ is inactive for CH4 oxidation. In addition, H migration from Pd active site to the support induced by hydrogen spillover can enhance the oxidation activity of CH4 in electric field. The conversion of carbonate/hydrogencarbonate to formate is an advantageous step in the methane oxidation process, with the active sequence being octahedral (111) > cubic (100) > rod (110) faces in/without electric field.

Computational analysis on transient MHD free convection flow in a microchannel in presence of inclined magnetic field with Hall and ion slip current

The present analysis is concerned with the effect of magnetic field inclination on transient MHD flow of Newtonian viscous fluid in a vertical microchannel with the consideration of Hall and ion slip currents as well as induced magnetic field effects. Obtained dimensional partial differential equation are rendered dimensionless by employing suitable parameters and thereafter solved numerically in MATLAB. Relevant actions of parameters on different flow features are depicted explicitly and also using Tables for various applicable parameters. Analysis in this direction is relevant in many MHD controlled applications. Results obtained from the present analysis shows that at the early stages of time and in the simultaneous occurrence of inclined magnetic field as well as Hall and ion slip currents, velocity and induced magnetic field behavior are found to be oscillatory all through the microchannel domain.

Ultrahigh Piezoelectric Response Obtained by Artificially Generating a Large Internal Bias Field in BiFeO3–BaTiO3 Lead‐Free Ceramics

AbstractPiezoelectric actuators are vital devices that convert electrical signals into mechanical strain, offering rapid and precise responses. Lead‐based piezoceramics have traditionally been the preferred choice for commercial piezoelectric actuators, while the low Curie temperature and the rising environmental concerns hinder their applications at high temperatures. In this study, a novel strategy is proposed to achieve high piezoelectric responses in lead‐free 0.67Bi1.05FeO3–0.33BaTiO3 (67BF‐33BT) ceramics with high Curie temperature by artificially generating a large internal bias field through repeat poling and aging treatments. A comprehensive exploration of how this internal bias field responds to applied electric fields and temperature variations has been conducted. The results suggest that the internal bias field originates from two aspects, one arises from the free charges that compensate for the depolarization field, while the other is attributed to the highly oriented defect dipoles. As a result of this internal bias field, the ceramics exhibit asymmetric strain–electric field (S–E) behaviors, resulting in a high strain (ε = 0.21%) and an extremely high piezoelectric coefficient (d33* = 1033.70 pm V−1) when subjected to low electric field (20 kV cm−1), along with good temperature stability from room temperature (RT) to 100 °C.