Non-homogeneous Field Research Articles

Abstract 2168: Testing the electrical properties of different cell lines using 3DEP reader and compare to TTFields response

Abstract Background: Tumor Treating Fields (TTFields) are an approved anti-neoplastic treatment modality delivered via application of low intensity, intermediate frequency, alternating electric fields. The electrical properties of cells (such as permittivity and conductivity) determine the optimal frequency of TTFields that incurs the highest reduction in cell counts. Currently, there are no predictive markers for determining TTFields response or the optimal frequency to be applied for individual patient. The goal of this study is to determine the correlation between electrical properties of cells and TTFields’s optimal frequency and sensitivity. The 3DEP reader (LabTech) determines the electrical properties of cells, including permittivity and conductivity, by using Dielectrophoresis (DEP) force. DEP is a physical effect that generates a force on polarizable particles experiencing a non-homogeneous electric field and can therefore be used as a technique to analyse the way cells move within electric fields at different frequencies. Methods: The baseline electrical properties (permittivity and conductivity) of 17 cell lines from different tumor types were determined using the 3DEP reader (LabTech). The curves were analyzed using 2-way ANOVA. The optimal TTFields frequency for each cell line was determined by testing the cytotoxic effect of TTFields at various frequencies using the inovitro system. The electrical properties of cells were compared with the optimal TTFields frequency and sensitivity of each cell line. Results: The results demonstrate significant differences (p<0.001) between the lower frequency range of the 3DEP curves that corresponds to membrane capacitance of cells with TTFields optimal frequency of 150kHz (9 cell lines) and cells with TTFields optimal frequency of 200kHz (8 cell lines). Membrane capacitance was also a good predictor for TTFields sensitivity based on the differences in the curves in the low frequency range. Conclusions: The results presented in this study demonstrate that cell membrane capacitance correlates with TTFields optimal frequency and sensitivity. Based on the above, there is a strong rational to further explore the potential of measuring the electrical properties of cells as a predictive marker to help determine which patient will respond better to TTFields and the optimal TTFields frequency to be applied for each patient. Citation Format: Moshe Giladi, Einav Zeevi, Karnit Gotlib, Cornelia Wenger, Ariel Naveh, Zeev Bomzon, Eilon D. Kirson, Uri Weinberg, Adrian Kinzel, Yoram Palti. Testing the electrical properties of different cell lines using 3DEP reader and compare to TTFields response [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2168.

Aging continuous time random walks in fluids

The subject of aging continuous time random walks (CTRWs) has attracted increasing attention in recent years. To describe the aging behaviors of random particles whose jumps are biased by a nonhomogeneous velocity field, we propose herein a generalized scheme of aging CTRWs in flows and obtain the corresponding generalized master equation in Fourier–Laplace space for probability density functions. Moreover, we derive the generalized aging advection diffusion equation for particles with a power law waiting time and Gaussian jump length densities, investigate the corresponding ensemble and time mean square displacements, and show how anomalous diffusion depends on the age of the process and on the moving fluids.

Spatiotemporal Metrology of Broadband Optical Pulses

Accurately characterizing the field of broadband optical pulses is required for developing new optical sources, performing successful experiments, and interpreting experimental results. Temporal diagnostics for short optical pulses are now well established. The most recent developments in ultrafast metrology focus on determining the field as a function of time (conversely frequency) and space, potentially revealing the field's nonhomogeneity and coupling between these variables. After a review of common situations where a nonhomogeneous spatiotemporal field is used as a tool or is the outcome of nonideal conditions, historical and state-of-the-art techniques for spatiotemporal ultrafast metrology are described. The different classes of techniques demonstrate the richness of the fundamental and technical developments in this domain.

Analysis of Mine Ventilation Network by 1D FEM: Simulation of Fans and Natural Draught

The version of simulating fans in mine ventilation network analysis by using the combination of FEM with the laminar solution method is considered. Two ways of fan insertion are discussed: in the form of a separate active element and in the form of combined element (an active element inserted into a passive element). The latter approach allows changing a position of the fan in a design stage without renumbering of a grid. The method of chords is used to linearize in general nonlinear fan characteristic. It is shown that the dependence of air discharge on the upstream-downstream pressure difference is an ascending curve for the fan. This provides a convergence for the iterative procedure of solving the FEM nonlinear equations system. A method of calculation of convective heat transfer between the air flow and the rock wall based on Lyon’s solution for a pipe with the constant density of boundary heat flow is described. As the density of heat flow and the air properties are slowly varying functions along a mine working (a branch of a network), then discretizing each branch into small segments permits to consider these parameters as constant along segments. Calculation of nonhomogeneous temperature field and treatment of gravity allow modelling the natural draught effect. The results of solution of the test problems validating used algorithms are given. Calculation results of flow mass rate in a mine network within the year are also represented which make it possible to estimate the influence of natural draught on venting capability.

Wettability Manipulation by Interface-Localized Liquid Dielectrophoresis: Fundamentals and Applications.

Electric field-based smart wetting manipulation is one of the extensively used techniques in modern surface science and engineering, especially in microfluidics and optofluidics applications. Liquid dielectrophoresis (LDEP) is a technique involving the manipulation of dielectric liquid motion via the polarization effect using a non-homogeneous electric field. The LDEP technique was mainly dedicated to the actuation of dielectric and aqueous liquids in microfluidics systems. Recently, a new concept called dielectrowetting was demonstrated by which the wettability of a dielectric liquid droplet can be reversibly manipulated via a highly localized LDEP force at the three-phase contact line of the droplet. Although dielectrowetting is principally very different from electrowetting on dielectrics (EWOD), it has the capability to spread a dielectric droplet into a thin liquid film with the application of sufficiently high voltage, overcoming the contact-angle saturation encountered in EWOD. The strength of dielectrowetting depends on the ratio of the penetration depth of the electric field inside the dielectric liquid and the difference between the dielectric constants of the liquid and its ambient medium. Since the introduction of the dielectrowetting technique, significant progress in the field encompassing various real-life applications was demonstrated in recent decades. In this paper, we review and discuss the governing forces and basic principles of LDEP, the mechanism of interface localization of LDEP for dielectrowetting, related phenomenon, and their recent applications, with an outlook on the future research.

Development and simulations of Enhanced Lateral Drift Sensors

We present the concept of a new type of silicon tracking sensor called Enhanced Lateral Drift (ELAD) sensor. In ELAD sensors the spatial resolution of the impact position of ionising particles is improved by a dedicated charge sharing mechanism, which is achieved by a non-homogeneous electric field in the lateral direction in the sensor bulk. The non-homogeneous electric field is created by buried doping implants with a higher concentration with respect to the background concentration of the bulk. The resulting position-dependent charge sharing allows for an improved interpolation of the impact position. TCAD-based electric field simulations for 2D and 3D geometries as well as transient simulations with a traversing particle for the 2D geometry have been carried out. The electric field profiles have further been optimised for position resolution. The simulations show a strong dependence of the charge sharing mechanism on the buried implant concentration. Optimal values for the buried implant concentration allow for nearly linear charge sharing between two readout electrodes as a function of the impact position. Additionally, the foreseen production technique combining silicon epitaxy and ion beam implantation is outlined.

Self-assembly of a two-dimensional molecular layer in a nonhomogeneous electric field: Kinetic Monte Carlo simulations.

Behavior of mobile adsorbed species can be affected by the presence of a strong non-homogeneous electric field. Such a field exists in the proximity of a biased tip of the scanning tunneling microscope. Depending on the electronic properties of the adsorbate and the polarity of the electric field, self-assembly of ordered structures on the surface can be facilitated or prevented. We use a kinetic Monte Carlo model to investigate the effect of the electric field on the assembly of planar molecules on weakly interacting surfaces. Using phthalocyanine molecules as a model system, we study mechanisms behind the results of our previous experimental study of electric-field controlled switching of molecular arrays. The complex interplay between intermolecular and field-molecule interactions is illustrated by detailed phase diagrams at various surface coverages.

Graviton-photon mixing

In the era of gravitational wave (GW) detection from astrophysical sources by LIGO/VIRGO, it is of great importance to take the quantum gravity effect of graviton-photon (GRAPH) mixing in the cosmic magnetic field to the next level. In this work, we study such an effect and derive for the first time perturbative solutions of the linearized equations of motions of the GRAPH mixing in an expanding universe. In our formalism we take into account all known standard dispersive and coherence breaking effects of photons such as the Faraday effect, the Cotton-Mouton (CM) effect, and the plasma effects in the cosmic magnetic field. Our formalism, applies to a cosmic magnetic field either a uniform or a slowly varying non-homogeneous field of spacetime coordinates with an arbitrary field direction. For binary systems of astrophysical sources of GWs at extragalactic distances with chirp masses $M_\text{CH}$ of a few solar masses, GW present-day frequencies $\nu_0\simeq 50-700$ Hz, and present-day cosmic magnetic field amplitudes $\bar B_0\simeq 10^{-10}-10^{-6}$ G, the power of electromagnetic radiation generated in the GRAPH mixing at present is substantial and in the range $P_\gamma\simeq 10^6-10^{15}$ (erg/s). On the other hand, the associated power flux $F_\gamma$ is quite faint depending on the source distance with respect to the Earth. Since in the GRAPH mixing the velocities of photons and gravitons are preserved and are equal, this effect is the only one known to us, whose certainty of the contemporary arrival of GWs and electromagnetic radiation at the detector is guaranteed.

THE GENERALIZED ENTROPY ERGODIC THEOREM FOR NONHOMOGENEOUS MARKOV CHAINS INDEXED BY A HOMOGENEOUS TREE

In this paper, we extend the strong laws of large numbers and entropy ergodic theorem for partial sums for tree-indexed nonhomogeneous Markov chains fields to delayed versions of nonhomogeneous Markov chains fields indexed by a homogeneous tree. At first we study a generalized strong limit theorem for nonhomogeneous Markov chains indexed by a homogeneous tree. Then we prove the generalized strong laws of large numbers and the generalized asymptotic equipartition property for delayed sums of finite nonhomogeneous Markov chains indexed by a homogeneous tree. As corollaries, we can get the similar results of some current literatures. In this paper, the problem settings may not allow to use Doob's martingale convergence theorem, and we overcome this difficulty by using Borel–Cantelli Lemma so that our proof technique also has some new elements compared with the reference Yang and Ye (2007).

Behavioral study of high-order harmonics and attosecond pulse generation in a spatially non-homogeneous laser field

Using the metallic nano-antennas we can enhance the intensity of a laser pulse to prepare it for high-order harmonic generation. Plasmonic resonances in the metal surfaces cause a non-homogeneous enhancement of the incoming laser field. In this article behavior of the generated high-order harmonics and attosecond pulses with respect to the location of a helium ion in the non-homogeneous field is investigated. It is cleared that the broader supercontinuum can be observed for the case when the ion target located around the center of non-homogeneity which leads to more intense and shorter attosecond pulses.

TVDal: Total variation diminishing scheme with alternating limiters to balance numerical compression and diffusion

Total variation diminishing (TVD) advection schemes are widely used in ocean modelling. Due to the constraints of flux limiters, TVD schemes with common single flux limiters of second-order or third-order accuracy exhibit defects associated with numerical compression or diffusion. To reduce the numerical errors induced by these numerical defects, a TVD method employing alternating flux limiters (TVDal) is proposed. The principle of TVDal is to alternately use a compressive and a diffusive limiter in different time steps. Through balancing the compression of the Superbee limiter and the diffusion of other flux limiters, a reduction of ∼60% of numerical errors in one-dimensional benchmark tests can be achieved with the TVDal scheme. In addition, the TVDal scheme combined with the Strang-splitting method is proposed for multi-dimensional advection. For an idealized 2D experiment with oblique advection, the Strang-splitting TVDal scheme features good shape retention with much lower numerical errors. The TVDal scheme has also been applied to model tidally induced internal lee waves, indicating that TVDal has the potential ability to balance the numerical compression and diffusion of conventional TVD schemes for cases with highly nonlinear, stratified, and nonhomogeneous flow fields. Finally, the principles of the TVDal scheme also show the potential application to conventional high-order TVD schemes.

A High-Precision Tracking Algorithm for Mass Reconstruction of Heavy-Ion Fragments in the R3B Experiment at FAIR

The multi-purpose R3B (Reactions with Relativistic Radioactive Beams) setup at the future FAIR facility in Darmstadt will be used for various experiments with exotic beams in inverse kinematics. In front and after the reaction target a combination of detectors serves for particle identification and momentum measurements. In order to perform a high-precision charge identification of heavy-ion fragments and achieve a momentum resolution of 10-3 following is required: a time of flight (ToF) measurement with up to 15 ps accuracy, position determination on the order of less than 0.5 mm and a dedicated algorithm for the heavy-ion tracking in highly non-homogeneous dipole field. With these constraints a tracking package is being developed and tested within the R3B software framework, this package has to go into production in fall of 2018. An iterative approach has been chosen for simultaneous track finding and fitting. The design and concept of the package are introduced in this paper, also the tests and the resolution measured with simulated data are presented.

Application of silicon-based camera for measurement of non-homogeneous thermal field on realistic specimen surface

The high-cost low-resolution infrared cameras operating in middle infrared spectral ranges are widely used to detect the thermal fields. In this study, a low-cost high-resolution silicon-based sensor camera operating in near infrared spectral ranges is used to perform the observation of the thermal fields on the realistic steel specimen surface. In near-infrared spectral ranges, a small temperature variation led to a large modification in the sensor illumination, inducing acquired images with over saturation or poor dynamic range of gray levels. To address this problem, an algorithm was used to precisely adjust the exposure time to acquire images with constant gray level whatever the temperature evolution is, and then used in heating experiment of a steel specimen. Results showed that images with constant gray level could be acquired during the heating experiment. A special radiometric model was used to perform near-infrared thermography. Based on this radiometric model of steel specimen surface, the thermal fields on steel specimen surface were successfully reconstructed without measuring surface emissivity.

Non-linear dynamics of the Villari effect in the presence of a non-homogeneous magnetic field

Investigations of systems with an active magnetostrictive element generally assume the presence of an external homogeneous bias magnetic field. This article, however, presents the results of a study investigating a bimorph magnetostrictive-aluminium beam vibrating in a non-homogeneous bias field. By comparing results obtained under different operating conditions of the system, the combined effect of the non-linear beam stress and the non-homogeneous external magnetic field on the dynamics of the Villari phenomenon is determined. The preliminary results prove that the application of non-linear magnetic fields to the magnetostrictive devices ensures the extension of energy harvesting bandwidth of these devices and can be used to improve their control possibilities. A study of time series and hysteresis loops provides more detailed information about the non-linear magnetization and dynamics of the system.

A bond-based micropolar peridynamic model with shear deformability: Elasticity, failure properties and initial yield domains

A generalized micropolar bond-based Peridynamic model with shear deformability for linear and non-linear problems is proposed. The analytical implicit formulation is derived from the definition of a specific microelastic energy function for micropolar nonlocal lattices, giving particular attention to numerical implementation aspects of the model. We investigate the effectiveness of this formulation, empathizing the importance of considering particle’s rotations in enriched bond-based peridynamic models with arbitrary Poisson’s ratios. Numerical analyses show that a microelastic energy function dependent on a shear deformation measure in which rotational degrees of freedom of the particles are not included, leads to a model not capable to describe properly the elastic behavior of isotropic solids subjected to non-homogeneous deformation fields. Moreover two novel deformation-based failure criteria for micropolar peridynamics accounting for bond shear deformation, associated or not with the corresponding stretch of the ligament, are proposed. A deep investigation is carryied out on the direction dependency of the failure response of the lattice, considering different horizon/grid spacing ratios. In this way the maximum errors are estimated and the effective initial yield domains corresponding to the failure criteria presented are identified in two dimensional principal s1−s2 and generalized s−γ deformations space.

Asymptotic Properties of the Method of Observead Means for Nonstationary Random Fields

The author considers a stochastic programming problem where the estimator is approximated by its empirical estimate based on observations of a non-homogeneous random field with continuous time and strong mixing. The strong consistency of this estimate is investigated and its asymptotic distribution is found under the constraint imposed on the unknown parameter in the form of systems of inequalities.

Uniform electric field enabled multi-needles electrospinning head based on trapezoid arrangement

The electrospinning electric field is the main factor responsible for the jet stretching force. Previous studies showed that nonhomogeneous electric field would affect the jets formed during the multi-needles electrospinning. Therefore, a multitude of methods were explored to optimize the electric field in multi-needles electrospinning, such as adjusting the supplied voltage on each needle, varying the space of the needles and spatial distribution of the needles. In this paper, three categories of needles distribution were explored for a homogeneous electric field and the design of a higher needles density of electrospinning head. The theoretical and experimental results showed that the homogeneous electric field formed with the trapezoidal head at 15mm distance while the others’ head required over 30mm. Hence, the trapezoidal arrangement is a better multi-needles distribution for electrospinning head, and has much more significance for high yield of electrospinning nanofibers.

Electrostrictive Mechanism of Liquid Breakdown in Strongly Nonhomogeneous Field under the Action of Nanosecond Voltage Pulse

Electrostriction mechanism of breakdown in polar liquid caused by high-voltage nanosecond pulse is studied. Nonstationary motion of liquid in the pin-to-plane system exposed to a pulse with peak voltage of 30 kV and 6-ns duration is numerically analyzed. Cavities in which the breakdown can be initiated are formed in the vicinity of the tip electrode. Dimensions of such cavities are estimated, and the conditions for formation are formulated. Profiles of voltage and current pulses are measured for breakdown in water and air. The velocity of breakdown development in air is determined using the time delay of the pulse measured by the shunt of discharge current at several interelectrode distances. The proposed method has limitations in the measurement of breakdown in water due to the effect of displacement current that exceeds the discharge current.

Simulation of nonhomogeneous fluctuating wind speed field in two-spatial dimensions via an evolutionary wavenumber-frequency joint power spectrum

Spectral representation method (SRM) is a widely-used tool for the simulation of fluctuating wind speed fields. To circumvent the computational challenges of the Cholesky decomposition involved in the spectral representation method, a wavenumber-frequency joint power spectrum based SRM was proposed recently. The method can be used for the efficient simulation of homogeneous and nonhomogeneous wind fields in one spatial dimension. In this paper, the wavenumber-frequency joint power spectrum based SRM is extended to simulate nonhomogeneous wind fields in two spatial dimensions. To this end, a closed-form evolutionary wavenumber-frequency joint spectrum is first derived, and integrated readily with the updated spectral representation method. To enhance the computational efficiency with respect to the threefold summation over the one-dimensional frequency domain and the two-dimensional wavenumber domain, two uneven-discretization strategies are proposed. They are associated with a tensor-product scheme and an acceptance-rejection criterion. For illustrative purposes, a numerical example of simulating a fluctuating wind speed field in two spatial dimensions associated with the rotating blades of a 5-MW wind turbine is considered. It is shown that both the proposed methods have good accuracy and efficiency, and the rejection-acceptance criterion based uneven discretization method is preferred to practical applications.

An Analysis of Characteristics of Magnetostatic Waves Propagating in Nonhomogeneous Fields Across the Ferrospinel Film Thickness

The amplitude-frequency characteristics (AFCs) of magnetostatic waves in the films of magnesium-manganese ferrospinels with nanostructured inhomogeneities are discussed. A common effect, observed in the film AFCs under different process conditions, is the ‘oscillations of propagation’ of magnetostatic waves as a function of the frequency. The oscillation pattern is thought to depend on the inhomogeneous exchange parameters and the surface anisotropy constants. The wave instability is characterized by the resonant interaction of the dipole magnetostatic waves with the surface spin waves. It is shown that the ferrospinel films with periodic nanostructured inhomogeneities of 30–40 nm could be treated as magnon crystals. An inclusion of the inhomogeneity into consideration allows one to provide reasoning for the formation of the rejection bands within the range 9–12 GHz, whose frequencies correspond to Bragg frequencies.