Field Generation Research Articles

Pyroelectric Janus nanomotors for synergistic electrodynamic-photothermal-antibiotic therapies of bacterial infections.

Antibacterial electrotherapy is currently activated by external electric field or self-powered generators, but usually needs complicated power management circuits. Herein, near-infrared illumination (NIR) of pyroelectric nanoparticles (NPs) produces a built-in electric field to address the effectiveness and safety concerns in the antibacterial treatment. Janus tBT@PDA NPs were obtained by capping polydopamine (PDA) on tetragonal BaTiO3 (tBT) NPs through defining the polymerization time, followed by ciprofloxacin (CIP) loading on the PDA caps to fabricate Janus tBT@PDA-Cip NPs. NIR illumination of PDA caps creates temperature variations on tBT NPs to generate photothermal and pyroelectric effects. Finite element simulation reveals a pyroelectric potential of over 1 V and sufficient reactive oxygen species (ROS) are produced to exhibit pyroelectric dynamic therapy (PEDT). The elevated temperature on one side of the Janus NPs produces thermophoretic force to drive NP motion, which enhances interactions with bacteria and overcomes limitations in the short action distance and lifespan of ROS. The pyroelectric field accelerates CIP release through weakening the π-π stacking and electrostatic interaction with PDA and also interrupts membrane potentials of bacteria to enhance CIP invasion into bacteria. The synergistic antibacterial effect of pyroelectric tBT@PDA-Cip NPs causes the fully recovery of S. aureus-infected skin wounds and regeneration of intact epidermis, blood vessels and hair follicles, while no obvious pathological change or inflammatory lesion is detected in the major organs. Thus, the pyroelectric Janus nanomotors demonstrate synergistic PEDT/photothermal/antibiotic effects to enhance antibacterial efficacy while avoiding the necessity of excessive heat, ROS and antibiotic doses. STATEMENT OF SIGNIFICANCE: : Antibacterial treatment is challenged by antibiotics-derived side effects and the evolution of resistant strains. Phototherapy is commonly associated with excessive heat and oxidative stress, and their combinations with other agents are especially encouraged to strengthen antibacterial efficacy while alleviating the associated side effects. Electric field is another activator to generate antibacterial abilities, but usually requires complicated power management and bulk electrodes, making it inconvenient in a biological setup. To address these challenges, we propose a strategy to generate microelectric field on nanoparticles themselves and achieve synergistic electrodynamic-photothermal-antibiotic therapies. The pyroelectric effect weakens interactions between nanoparticles and antibiotics to accelerate drug release, and the built-in pyroelectric field increases membrane fluidity to enhance bacterial uptake of antibiotics.

Topology Optimization of an Electromagnet Manipulator for 3-D Uniform Magnetic Field Generation

Magnetic manipulation is a method used for biomedical applications to remotely control micro-robots in a contactless manner. The electromagnet manipulator should control a magnetic field with 3 degrees of freedom inside a region of interest. In various case studies, this field results from the superposition of three decoupled uniform magnetic fields. Each of them is individually generated by a different pair of Helmholtz coils. Such an arrangement requires the pairs to be nested within each other, inevitably reducing the working area’s size and degrading the whole system’s performance and integration. The proposed work aims to design a novel electromagnetic manipulator with the help of computational design, to explore beyond the Helmholtz coils arrangement. A topology optimization framework is developed for this purpose. It investigates the distribution of coils that achieves the best field uniformity for a fixed footprint while keeping the different degrees of freedom balanced.

HydraMarker: Efficient, Flexible, and Multifold Marker Field Generation.

An n-order marker field is a special binary matrix whose n×n subregions are all distinct from each other in four orientations. It is commonly used to guide the composing process of position-sensing markers, which can be detected and identified in a camera image with very limited scope or severe visibility problems. Despite the advantages, position-sensing markers are rare and overlooked because generating marker fields is difficult. In this article, we broaden the definition of marker field, making it more powerful and flexible. Then, we propose bWFC (binary wave function collapse) and its high-speed version, fast-bWFC, to solve the generation problem. The methods are packaged into an open-sourced toolkit named HydraMarker, with which, users not only can generate marker fields on laptops within a short period of time, but also can highly customize them: preset values; fields and subregions in any shape; multifold local uniqueness. Comparative results indicate that the proposed method has superior efficiency, quality, and capability. It makes marker field generation accessible to common marker designers, opening up more possibilities for fiducial markers.

Thermal maturity evolution and hydrocarbon generation in the Dibeilla oil field, Termit Basin, Eastern Niger: an organic geochemical and basin modeling approach

Thermal maturity evolution and hydrocarbon generation in the Dibeilla oil field, Termit Basin, Eastern Niger: an organic geochemical and basin modeling approach

A low-magnetic packaging for a distributed Bragg reflector laser diode chip for atomic sensor applications

We implement a distributed Bragg reflector (DBR) laser diode (LD) package with low-magnetic field generation. The package consists of a commercial 795 nm DBR LD chip, a thermo-electric cooler (TEC), a thermistor, a flexible printed circuit board (FPCB) which cancels the magnetic field emitted by the TEC current flow, and a non-magnetic aluminum case. We confirm that the magnetic dipole moment of our low-magnetic package body is about three orders of magnitude smaller than that of a commercial DBR laser package. Moreover, it is shown that our compensating FPCB, the effectiveness of which is supported by computer simulations, reduces the magnetic field magnitude by a factor of 2.2. The FPCB also reduces the magnetic field gradient emitted by the TEC current flow so that gradient-induced spin relaxations are suppressed in applications. A portable optically pumped atomic magnetometer (OPAM) utilizing two low-magnetic packages as light sources is reported as an application of the package and shows a 0.30 pT/Hz1/2 level magnetic sensitivity at a 69 μT external magnetic field; in contrast, the OPAM utilizing the commercial packages showed a magnetic sensitivity of 0.87 pT/Hz1/2.

The characteristics of gas-liquid dispersive mixing and microbubble generation in turbulent adjustable jet flow field

In this study, the gas-liquid two-phase mixing process and the microbubbles formation process in a jet flow field has been investigated by using a self-designed on-line measurement system for measuring bubble generation characteristics and the Volume of Fluid (VOF) model in numerical simulation methods for analyzing flow field distribution characteristics. The effect of turbulence intensity on the dynamic size distribution of microbubble has been considered. The characteristics and duration of the three stages during the bubble breaking process, namely, surface oscillation stage, surface tension stage and fracture stage, were analyzed. The results show that the increase of turbulence intensity in jet flow will further promote the imbalance between the external deformation force and the surface tension resisting the deformation of the bubble, and promote the breaking probability of bubble. However, when the bubble breaks to a sufficiently small size, the surface tension against bubble deformation will increase sharply, the surface free energy needed to overcome for bubble breakage is very large, and the breakage probability of bubble will significantly decrease. Compared with the breaking process of bubbles, the increase in turbulence intensity will greatly promote the bubble coalescence process, which will ultimately become the main reason for affecting the bubble size distribution. Moreover, the influence of flow field distribution characteristics on bubble size distribution and average bubble size change is analyzed by using Population Balance Model.

Thermal Evolution, Hydrocarbon Generation, and Heat Accumulation of a High Geothermal Coalfield: A Case Study of Pingdingshan Coalfield, China.

As an important energy base in central China, the Pingdingshan coalfield has abundant coal and geothermal resources. The cooperative exploration of coal and geothermal resources is significant for the comprehensive utilization of energy resources. This work collected coal-bearing samples from the Pingdingshan coalfield to investigate the tectono-thermal evolution of a high geothermal coalfield, especially the present geothermal field and hydrocarbon generation model. The geochemical results show that the Shanxi and Taiyuan source rocks have average R o values of 0.88 and 0.97%, respectively, with an average Rock-Eval T max value of 442 °C. Hydrocarbon generation of source rocks started at ∼205 Ma, with the highest rates at ∼170 Ma, reaching the maximum transformation ratio of 40-50% in the middle of the Early Cretaceous. The age and length of apatite fission tracks (AFTs) indicate that coal-bearing strata underwent significant post-depositional annealing after the Late Permian and suggest an abnormal thermal event that occurred in the Late Mesozoic. Meso-Cenozoic thermal event was mainly caused by the plutonic metamorphism of the Early Jurassic and magmatic thermal metamorphism of the Early Cretaceous, achieving a maximum paleotemperature of ∼140 °C. The magmatic thermal event resulted from the intensive post-orogenic extension of the Qinling-Dabie Orogenic Belt caused by the tectonic transition of the North and South China Plates. The present-day high geotemperature of Pingdingshan Coalfield is dominated by the horst structure caused by the regional extension of the basin-mountain system. The Cambrian limestone with a high thermal conductivity underlying coal measure collects deep heat, forming a heat accumulation center of this horst structure with a heat flow of 74 mW/m2 and a maximum temperature of ∼50 °C nowadays.

Eigenanalysis of vector autoregressive model for optimal fitting of a predefined cross power spectral density matrix: Application to numeric generation of stationary homogeneous isotropic/anisotropic turbulent wind fields

Turbulent wind fields representing realistic atmospheric conditions are required for wind turbine load calculations. For a statistically stationary situation, the wind loads on a wind turbine depend, among other wind characteristics, on the spectra and spatial coherences of the velocity field in the rotor plane (i.e. the cross-power spectral density matrix). In this study, a novel approach is proposed to optimally calibrate the parameters of a vector autoregressive model for reproducing a predefined target cross-power spectral density matrix to be used for the synthetic generation of turbulent wind fields. This approach is based on the eigenanalysis of the companion matrix of the vector autoregressive model. In this work, the cross-power spectral density matrix, for different turbulent wind conditions, is considered as targets. This approach is compared to the state-of-the-art approaches for calibration of parameters of vector autoregressive models. The discussion covers the implications derived from approaching the vector autoregressive model determination in the frequency domain or in the time domain.

Исключение интегрального члена в уравнениях одной эредитарной системы, связанной с задачей гидромагнитного динамо

В работе изучается двумерная система интегро-дифференциальных уравнений, которая является простейшей эредитарной моделью двумодового гидромагнитного динамо. Учет пространственной и временной нелокальности взаимодействий в динамо-системах сейчас активно исследуется. В маломодовых приближениях уравнений динамо можно рассматривать только временную нелокальность, т.е. эредитарность (память). Память в исследуемой системе реализована в виде обратной связи, распределенной по всем прошлым состояниям системы. Обратная связь представлена с помощью интегрального члена типа свертки от квадратичной комбинации фазовых переменных с ядром достаточно общего вида. Этот член моделирует подавление турбулентного генератора поля (α-эффекта) квадратичной формой от фазовых переменных. В реальных динамо-системах такое подавление обеспечивается силой Лоренца. Основной результат работы – доказательство возможности исключения интегрального члена для одного класса ядер. Такие ядра являются решениями однородного линейного дифференциального уравнения с постоянными коэффициентами. Доказано, что исследуемую интегро-дифференциальную систему можно заменить дифференциальной системой большей размерности с подходящими начальными условиями на дополнительные фазовые переменные. Если ядро является решением уравнения n-го порядка, то размерность системы может достигать 3n−2 и зависит от начальных условий, которым удовлетворяет ядро. В работе используются классические методы теории дифференциальных уравнений. Приводятся примеры динамических систем, возникающих при некоторых ядрах в результате исключения интегрального члена. Результаты работы можно использовать для верификации вычислительных алгоритмов и программных кодов, разработанных для решения интегро-дифференциальных уравнений.We study a two-dimensional system of integro-differential equations, which is the simplest hereditary model of a two-mode hydromagnetic dynamo. Accounting for the spatial and temporal nonlocality of interactions in dynamo systems is currently being actively studied. In the low-mode approximations of the dynamo equations, one can consider only temporal nonlocality, i.e. heredity (memory). Memory in the system under study is implemented in the form of feedback distributed over all past states of the system. The feedback is represented by a convolution-type integral term of a quadratic combination of phase variables with a fairly general kernel. This term models the quenching of the turbulent field generator (α-effect) by a quadratic form in phase variables. In real dynamo systems, such quenchingn is provided by the Lorentz force. The main result of the work is a proof of the possibility of eliminating the integral term for one class of kernels. Such kernels are solutions of a homogeneous linear differential equation with constant coefficients. It is proved that the studed integro-differential system can be replaced by a higher-dimensional differential system with suitable initial conditions for additional phase variables. If the kernel is a solution to an n-order equation, then the dimension of the system can reach 3n−2 and depends on the initial conditions that the kernel satisfies. The work uses classical methods of the theory of differential equations. Examples are given of dynamical systems that arise for some kernels as a result of the elimination of the integral term. The results of the work can be used to verify computational algorithms and program codes developed for solving integro-differential equations.

Nonlinear Parametric Resonance in the Simplest Model of a Solar Dynamo

The properties of nonlinear parametric resonance are investigated using the example of the low-mode Parker dynamo model. This model is a system of four ordinary differential equations and in the simplest approximation describes the processes of generation and oscillation of large-scale magnetic fields in stellar systems. In the absence of nonlinear effects, the problem under consideration, by analogy with a system of harmonic oscillations, admits an asymptotic division of multiple resonant frequencies. However, despite the fact that at first glance at these frequencies it is reasonable to expect an amplification of the amplitude in the nonlinear case, it is demonstrated that in the presence of nonlinear terms, the behavior of the system is significantly more complex. In particular, generation suppression can be observed at resonant or low frequencies, while amplification occurs in the immediate vicinity of the resonance or at sufficiently high frequencies. The reasons are discussed for this behavior, as well as the possibility of the influence of parametric resonance on the establishment of planetary dynamo cycles.

Near-boundary error reduction with an optimized weighted Dirichlet–Neumann boundary condition for stochastic PDE-based Gaussian random field generators

Random field generation through the solution of stochastic partial differential equations is a computationally inexpensive method of introducing spatial variability into numerical analyses. This is particularly important in systems where material heterogeneity has influence over the response to certain stimuli. Whilst it is a convenient method, spurious values arise in the near boundary of the domain due to the non-exact nature of the specific boundary condition applied. This change in the correlation structure can amplify or dampen the system response in the near-boundary region depending on the chosen boundary condition, and can lead to inconsistencies in the overall behaviour of the system. In this study, a weighted Dirichlet–Neumann boundary condition is proposed as a way of controlling the resulting structure in the near-boundary region. The condition relies on a weighting parameter which scales the application to have a more dominant Dirichlet or Neumann component, giving a closer approximation to the true correlation structure of the Matérn autocorrelation function on which the formulation is based on. Two weighting coefficients are proposed and optimal values of the weighting parameter are provided. Through parametric investigation, the weighted Dirichlet–Neumann approach is shown to yield more consistent correlation structures than the common boundary conditions applied in the current literature. We also propose a relationship between the weighting parameter and the desired length-scale parameter of the field such that the optimal value can be chosen for a given problem.

Micromagnetic model analysis of dual field generation layer (FGL) spin torque oscillators (STO) for microwave-assisted magnetic recording (MAMR)

Dual field generation layer (FGL) spin torque oscillators (STO) were investigated for use in microwave-assisted magnetic recording. The STOs were integrated into the gaps of write heads for stable oscillation. According to preliminary calculations, a FGL thickness of 5 nm was suitable, while the volume of 7.5 nm and 10 nm thick FGLs was too large and they did not oscillate stably. The most dominant factor influencing the FGL rotation was found to be the strength of the antiferromagnetic coupling between the FGLs. Other parameters were also varied, e.g., the exchange coupling between the negative spin injection layer (nSIL) and the trailing shield (TS), however, no significant effect was found. Unlike single FGL STOs, the oscillation frequency changed drastically, from 38 GHz to 73 GHz, on varying the injected current density to the STO. Recording simulations showed that the signal-to-noise ratio was maximized for an STO oscillation frequencies between 34 GHz and 50 GHz, depending on the recording media used in the calculations. Therefore, the dual FGL STO may be suitable for a wide range of recording media. Alternatively, the dual FGL STO may be used for dual-layer recording, where different resonance frequencies are needed for each of the layers, obviating the need for a second STO.

Rotationally equivariant super-resolution of velocity fields in two-dimensional flows using convolutional neural networks

This paper investigates the super-resolution of velocity fields in two-dimensional flows from the viewpoint of rotational equivariance. Super-resolution refers to techniques that enhance the resolution of an image from low to high resolution, and it has recently been applied in fluid mechanics. Rotational equivariance of super-resolution models is defined as the property by which the super-resolved velocity field is rotated according to a rotation of the input, leading to inferences that are covariant with the orientation of fluid systems. In physics, covariance is often related to symmetries. To better understand the connection with symmetries, the notion of rotational consistency of datasets is introduced within the framework of supervised learning, which is defined as the invariance of pairs of low- and high-resolution velocity fields with respect to rotation. This consistency is sufficient and necessary for super-resolution models to learn rotational equivariance from large datasets. Such a large dataset is not required when rotational equivariance is imposed on super-resolution models through the use of prior knowledge in the form of equivariant kernel patterns. Nonetheless, even if a fluid system has rotational symmetry, this symmetry may not carry over to a velocity dataset, which is not rotationally consistent. This inconsistency can arise when the rotation does not commute with the generation of low-resolution velocity fields. These theoretical assertions are supported by the results of numerical experiments, where two existing convolutional neural networks (CNNs) are converted into rotationally equivariant CNNs and the inferences of these CNNs are compared after the supervised training.

Efficient Generation of Axial Magnetic Field by Multiple Laser Beams with Twisted Pointing Directions.

Strong laser-driven magnetic fields are crucial for high-energy-density physics and laboratory astrophysics research, but generation of axial multikilotesla fields remains a challenge. The difficulty comes from the inability of a conventional linearly polarized laser beam to induce the required azimuthal current or, equivalently, angular momentum (AM). We show that several laser beams can overcome this difficulty. Our three-dimensional kinetic simulations demonstrate that a twist in their pointing directions enables them to carry orbital AM and transfer it to the plasma, thus generating a hot electron population carrying AM needed to sustain the magnetic field. The resulting multikilotesla field occupies a volume that is tens of thousands of cubic microns and it persists on a picosecond timescale. The mechanism can be realized for a wide range of laser intensities and pulse durations. Our scheme is well suited for implementation using multikilojoule petawatt-class lasers, because, by design, they have multiple beamlets and because the scheme requires only linear polarization.

Binary Volume Acoustic Holograms

In recent years, high-resolution additive manufacturing has enabled a diverse range of low-cost methods for ultrasonic wave-front shaping. Acoustic holograms, in particular, allow for the generation of arbitrary diffraction-limited acoustic fields at megahertz frequencies from single-element transducers. These are phase plates that function as direct acoustic analogs to thin optical holograms. In this work, it is shown that, by using multiple polymer three-dimensional (3D) printing, two-material (binary) acoustic analogs to ``thick'' or volume optical holograms can also be generated. First, an analytic approach for designing a volume hologram that diffracts a set of input fields onto a desired set of output fields is briefly summarized. Next, a greedy-optimization approach based on random downhill binary search able to account for the constraints imposed by the chosen fabrication method is introduced. Finally, an experimental test case designed to diffract the field generated by a 2.54-cm planar lead zirconate titanate (PZT) transducer onto eight distinct patterns dependent on the direction of the incident field is used to validate the approach and the design method. Field scans of the eight target fields demonstrate that acoustic analogs of optical volume holograms can be generated using multipolymer printing and that these allow the multiplexing of distinct fields onto different incident field directions.

Pyroelectric Janus nanomotors to promote cell internalization and synergistic tumor therapy

The tumor diffusion and cell internalization are the major obstacles to improving delivery efficacy of therapeutic agents. External electric fields have shown strong effect on the cell membrane polarization and fluidity, but usually need complicated power management circuits. Herein, in situ generation of microelectric field on nanoparticles (NPs) is proposed to overcome these delivery barriers. Janus tBT@PDA-CPT NPs were developed through partially coating of polydopamine (PDA) caps on pyroelectric tetragonal BaTiO3 (tBT) NPs and then camptothecin (CPT) conjugation via disulfide linkages. For comparison, cBT@PDA-CPT NPs were prepared from non-pyroelectric cubic BaTiO3 (cBT) as control. Near-infrared (NIR) illumination on PDA caps of the Janus NPs produces asymmetric thermophoretic force to drive NP motion for tumor accumulation, deep tissue penetration and effective cell interaction. Photothermally created temperature variations on tBT NPs build pyroelectric potentials to selectively change the membrane potential of tumor cells other than normal cells and exhibit a dominated role in enhancing tumor cell internalization and cytotoxicity. The combination index analysis confirms the synergistic effect of pyroelectric dynamic therapy (PEDT), chemotherapy and photothermal therapy (PTT), leading to full inhibition of tumor growth and noticeable extension of animal survival at significant lower CPT doses. The mild PTT/PEDT, the reduced CPT dose and the selective toxicity to tumor cells have achieved favorable treatment safety after tBT@PDA-CPT/NIR treatment. Therefore, in response to the differences in membrane potentials and glutathione levels between tumor and normal cells, we have demonstrated a concise design to achieve thermophoresis-driven motion, pyroelectric potential-enhanced cell internalization and PTT/PEDT/chemotherapy-synergized antitumor treatment.

Effect of laser intensity redistribution on terahertz field generation via laser wakefield in a magnetized plasma

Effect of laser intensity redistribution on terahertz field generation via laser wakefield in a magnetized plasma

On the quadruple Beltrami fields in thermally relativistic electron-positron-ion plasma

A thermally relativistic electron-positron-ion (EPI) plasma self-organizes into a quadruple Beltrami (QB) field. The QB field, which is the combination of four Beltrami fields, is described by four scale parameters. These scale parameters are often either real or both real and complex in nature. The values of the scale parameters are determined by Beltrami parameters, relativistic temperatures, and the densities of plasma species. It is demonstrated that all the scale parameters become real at higher relativistic temperatures and ion densities, which naturally lead to paramagnetic structures. It is also shown that the scale separation in the QB state provides the possibility of field and flow generation in such thermally relativistic plasmas. The present study may have implications for space, astrophysical and laboratory plasmas.

Moon’s Two Faces: Near-Side/Far-Side Maria Disparity

Any attempt to understand the origin of lunar maria must as well account for the dearth of maria on the far-side of the Moon. Various attempts have been made to explain the origin of lunar maria based solely upon obvious lunar processes, namely, volcanism and impact phenomena. Here I review a different explanation for the origin of lunar maria by analogy with observations of Earth, specifically related to its central nuclear fission georeactor. Georeactor formation is a natural consequence of density layering in oxygen-starved (highly-reduced) planetary matter and is ideally suited for magnetic field generation in planets and large moons. A portion of georeactor produced heat is channeled to Earth’s surface hot-spots, e.g., Hawaii and Iceland, where its georeactor origin is indicated by the high relative 3He/4He ratios observed, and seismically imaged heat channels extending to the top of the core. Massive basalt floods, e.g., Deccan and Siberian Traps were driven by georeactor-produced heat as indicated by the high relative 3He/4He ratios of their occluded helium. These terrestrial basalt floods suggest to me that the lunar maria might have similar origins driven by the Moon’s nuclear fission “lunar-reactor.” Remanent magnetization of some lunar surface material is indicative of an ancient internally-generated magnetic field. That implication is consistent with the magnetic fields produced by central nuclear fission reactors in many planets and large moons. The location of the lunar-reactor at the Moon’s center of mass, displaced 2 km toward the Earth-facing side, in concert with Earth’s tidal pull, I posit, is principally responsible for driving the maria-basalt floods toward the Earth facing side of the Moon. In principle, it should be possible to verify the correctness of this concept by measuring the helium isotopes of maria basalt samples taken from depths sufficient to be unaffected by solar wind implanted helium.

A Statistical Finite Element Method Integrating a Plurigaussian Random Field Generator for Multi-scale Modelling of Solute Transport in Concrete

A new model for the multi-scale simulation of solute transport in concrete is presented. The model employs plurigaussian simulations to generate stochastic representations of concrete micro- and meso-structures. These are idealised as two-phase medium comprising mortar matrix and pores for the micro-structure, and mortar and large aggregate particles for the meso-structure. The generated micro- and meso-structures are employed in a finite element analysis for the simulation of steady-state diffusion of solutes. The results of the simulations are used to calculate effective diffusion coefficients of the two-phase micro- and meso-structures, and in turn, the effective diffusion coefficient at the macro-scale at which the concrete material is considered homogenous. Multiple micro- and meso-structures are generated to account for uncertainty at the macro-scale. In addition, the level of uncertainty in the calculated effective diffusion coefficients is quantified through a statistical analysis. The numerical predictions are validated against experimental observations concerning the diffusion of chloride through a concrete specimen, suggesting that the generated structures are representative of the pore-space and coarse aggregate seen at the micro- and meso-scales, respectively. The method also has a clear advantage over many other structural generation methods, such as packing algorithms, due to its low computational expense. The stochastic generation method has the ability to represent many complex phenomena in particulate materials, the characteristics of which may be controlled through the careful choice of intrinsic field parameters and lithotype rules.