Fick's law, green-kubo formula, and Heisenberg's equation of motion

Fick's law is important in transport theory and nonequilibrium statistical mechanics. The Heisenberg equation of motion for density is examined to see how it could be reduced to the diffusion equation, which is exactly equivalent to Fick's law. Conditions that are required have been noted and their implications explored.     

Electron,Proton, Neutron as Spheroidical Particles

It is shown that it is possible to describe the electron and the proton at rest within the framework of Dirac's relativistic theory of particles as electro-magnetic stable, spheroidical particles like balloons with very thin envelopes. Their properties, especially their spins and their magnetic momenta, are exactly those, which have been measured at first and later on derived by Dirac. In this picture the neutron plays the rǒle of a system of two concentric and synchronically rotating balloons with a small distance between them at a positive energetic minimum of balance at 1.26 MeV. The magnetic moment of this particle has a negative sign and is of the correct size.     

Hydrodynamics, Particle Relabelling and Relativity

Using the wave equation as an example, it is shown how to extend the hydrodynamic Lagrangian-picture method of constructing field evolution using a continuum of trajectories to second-order theories. The wave equation is represented through Eulerian-picture models that are distinguished by their Lorentz transformation properties. Introducing the idea of the relativity of the particle label, it is demonstrated how the corresponding trajectory models are compatible with the relativity principle. It is also shown how the Eulerian variational formulation may be obtained by canonical transformation from the Lagrangian picture, and how symmetries in the Lagrangian picture may be used to generate Eulerian conserved charges.     

The sense of smell,its signalling pathways,and the dichotomy of cilia and microvilli in olfactory sensory cells

Smell is often regarded as an ancillary perception in primates, who seem so dominated by their sense of vision. In this paper, we will portray some aspects of the significance of olfaction to human life and speculate on what evolutionary factors contribute to keeping it alive. We then outline the functional architecture of olfactory sensory neurons and their signal transduction pathways, which are the primary detectors that render olfactory perception possible. Throughout the phylogenetic tree, olfactory neurons, at their apical tip, are either decorated with cilia or with microvilli. The significance of this dichotomy is unknown. It is generally assumed that mammalian olfactory neurons are of the ciliary type only. The existence of so-called olfactory microvillar cells in mammals, however, is well documented, but their nature remains unclear and their function orphaned. This paper discusses the possibility, that in the main olfactory epithelium of mammals ciliated and microvillar sensory cells exist concurrently. We review evidence related to this hypothesis and ask, what function olfactory microvillar cells might have and what signalling mechanisms they use.     

BCS-spin-model,its thermodynamic representations and automorphisms

In this paper two equivalent explicit realizations of the thermodynamic representations of the BCS-spin-model are constructed and since they are of well known form their type is easily determined. Time evolution and vacuum properties of these representations are studied and it is shown that in general the time development of the system is representation-dependent.     

Structural,mechanical, thermodynamics properties and phase transition of FeVSb

The structural, mechanical, thermodynamics properties and phase transition of FeVSb are investigated extensively using the first principle calculations and the quasi-harmonic Debye model. From the calculated elastic constants of cubic FeVSb, some other mechanical quantities, such as bulk modulus and Poisson's ratio, are drawn. Surprisingly, it is found that almost all these mechanical quantities are larger than those of CoVSb (Bo Kong et al., J. Alloys Compd. 509 (2011) 2611); the obtained corresponding transition pressure from fcc to hcp is also larger than that of CoVSb. For these distinctions, their complete different electronic and magnetic behaviors in their cubic structures may be responsible. However, in their hexagonal structures, atomic configurations are similar in terms of the analysis of both the ground-state structure and enthalpy–pressure curves. It is also shown that the elastic instability of cubic FeVSb does not appear with pressure up to 120 GPa and should not be a reason for the pressure-induced phase transition. In addition, heat capacity, Debye temperatures, and so on are obtained successfully for cubic FeVSb under the quasi-harmonic Debye model. Furthermore, we attempt to explore the phase diagram of FeVSb with the model.     

Neutron activation analysis of sea-, lake-, and evaporated salt

Salt is essential for human nutrition. Recently, it has become popular in Europe to rather use exotic sea salt or lake salt instead of purified evaporated salt, because of an alleged higher content of trace elements. In this study the content of trace elements and their bioavailability of 19 samples of different types of salt and 1 sample of brine purification sludge were investigated using instrumental neutron activation analysis. In general, sea-, lake-, and evaporated salt are quite pure. Trace elements determined in salt were Al, Br, Co, Cr, Cs, Fe, Rb, Sc, Sr, and Zn; some of them only in individual cases. It was found that, in general, the content of trace elements in sea- or lake salt was higher than in purified salt. Nevertheless, the use of sea- or lake salt does not contribute significantly to the human needs of essential trace elements, because their concentration in salt is too low or their compounds are not bioavailable.     

Gauge invariant unified field structures,quantizable dynamical systems,charge, and spin structures

Gauge invariant unified field structures on a manifold B are introduced. Necessary and sufficient conditions for their existence are studied. The connection with charge is studied; it is shown that such gauge invariant structures, e.g. quantizable dynamical systems, over simply connected manifolds B are completely classified by charge. Complex analytic gauge invariant unified field structures are studied. These structures over a complex analytic manifold B whose square is the canonical line bundle are in bijective correspondence with the spin structures on B. Finally, a class of homogeneous quantizable dynamical systems are shown not to carry spin structure.     

含平行裂缝储层中地震波频散、衰减、及频变各向异性*

裂缝厚度(张开度)对裂缝储层有效渗透率等起关键作用因而探测裂缝厚度对裂缝储层的勘探开发具有重要意义。针对此,该文主要介绍地震波在含平行裂缝储层中的频散、衰减及频变各向异性特征,及其与裂缝厚度的关系。重点探讨了流体运动与散射两种主要机制,并介绍了最新的理论模型研究进展。研究表明,裂缝厚度对流体运动与散射机制均会产生重大影响,主要影响频率范围为流体运动的高频区域和散射的低频区域。该频率范围常在地震频带内,故在实际地震勘探中应考虑裂缝厚度的影响,其同时为地震探测裂缝厚度提供了理论基础。最后,还探讨了流体运动与散射机制的耦合作用,并给出了相应的理论模型。结果表明,两种机制相互耦合时,地震波的频散衰减特征会发生明显变化,应予以考虑。     

MAX 相陶瓷的结构、制备及物理性能研究

MAX 相陶瓷因具有独特的 MX 片层与A 片层交替堆叠的晶体结构,使其兼具金属和陶 瓷的优良特性,如良好的导热导电性、可加工性,同时具有良好的抗氧化性、耐腐蚀性以及耐 摩擦磨损等性能,具有非常广泛的应用前景。本文首先介绍了 MAX 相陶瓷材料的种类与晶体 结构,并简述了近几年新发现的 MAX 相陶瓷材料以及制备手段的发展动态。之后从 MAX 相 物理性能的角度出发,重点综述了几种典型 MAX 相陶瓷材料的弹性性能、电学性能、热学性 能、磁性能以及抗辐照性能的研究进展。此外,进一步介绍了MAX 相的二维衍生物 MXene 的 衍生过程、超导性以及其在电化学储能、催化领域的研究进展。最后,本文从探索 MAX 相材 料新结构的多样性、MAX 相物理性能及相关理论计算、MXene 二维材料以及相应的制备、表 征和应用等方面,展望了 MAX 相陶瓷材料的潜在研究方向及应用前景,为 MAX 相和 MXene 材料的深入研究提供了新的思路。     

Coronal mass ejections: origins, evolution, and role in spaceweather

Coronal mass ejections (CMEs) are an important element of coronal and interplanetary dynamics. They can inject large amounts of mass and magnetic fields into the heliosphere, causing major geomagnetic storms and interplanetary shocks, which are a key source of solar energetic particles (E>1 MeV). Until recently, our understanding of the origins and early development of CMEs at the Sun was very limited. We knew that CMEs were frequently associated with erupting prominences and long-enduring X-ray arcades, but our physical understanding of how and why CMEs are initiated was poor. However, recent studies using the excellent data sets from the Yohkoh, SOHO, Wind, ACE and other spacecraft and ground-based instruments have improved our knowledge of the mass ejection process and how it effects space weather. The author reviews some of the well-determined coronal properties of CMEs, what is known about their source regions, and what their manifestations are in the solar wind. One exciting new type of observation is of halo-like CMEs, which suggest the launch of a geoeffective disturbance toward Earth. Several studies have shown a good correspondence between halo CMEs accompanied by near-sun center surface activity and subsequent magnetic clouds and geomagnetic storms at earth. In addition, halo CMEs are important for understanding the internal structure of CMEs since their source regions are near Sun center and near-earth spacecraft may be likely to sample material along their central axes     

Kolmogorov–Sinai Entropy, Lyapunov Exponents, and Mean Free Time in Billiard Systems

We perform new experiments on the Kolmogorov–Sinai entropy, Lyapunov exponents, and the mean free time in billiards. We study their dependence on the geometry of the scatterers made up of two interpenetrating square lattices, each one with circular scatterers with different radius. We find, in particular, that the above quantities are continuous functions of the ratio of the scatterer radius. However, it seems that their derivative is discontinuous around the radius ratio which separates the diffusive and nondiffusive types of geometries.     

Correlation between time functions of sound pressure, masking, and OAE suppression

Periodic sound-pressure time functions with frequency components below 50 Hz were used to measure within their period (a) the temporal course of masking, called a masking-period pattern (MPP), and (b) the temporal course of suppression of delayed evoked otoacoustic emissions, called a suppression-period pattern (SPP). Three different time functions were used: an alternating Gaussian impulse, its first integral, and its second integral. In each case, the course of the SPP is a mirror image of that of the MPP: Small masking corresponds to small suppression, while strong masking coincides with almost total suppression. Since otoacoustic emissions are assumed to have their origin in the inner ear, it can be argued that simultaneous masking, an effect including central processing, is very strongly based on peripheral processes located in the cochlea. Both MPP and SPP are closely related to the second derivative of the sound-pressure time function.     

Entangled networks, synchronization, and optimal network topology

A new family of graphs, entangled networks, with optimal properties in many respects, is introduced. By definition, their topology is such that it optimizes synchronizability for many dynamical processes. These networks are shown to have an extremely homogeneous structure: degree, node distance, betweenness, and loop distributions are all very narrow. Also, they are characterized by a very interwoven (entangled) structure with short average distances, large loops, and no well-defined community structure. This family of nets exhibits an excellent performance with respect to other flow properties such as robustness against errors and attacks, minimal first-passage time of random walks, efficient communication, etc. These remarkable features convert entangled networks in a useful concept, optimal or almost optimal in many senses, and with plenty of potential applications in computer science or neuroscience.     

碳、氮和氧族元素取代对2,1,3-苯并噻二唑衍生物的电子、光谱、电荷传输性质影响的理论研究

采用量子化学方法设计并研究了一系列CH₂、NH、O和Se取代的2,1,3-苯并噻二唑衍生物的电子性质、光谱性质和电荷传输性质．采用的研究方法是从头算Hartree-Fock和密度泛函方法．研究结果表明,中心芳环的S原子分别被CH₂、NH、O和Se取代后,母体分子的电子性质、光谱性质以及电荷传输性质得到了很好的调节．根据得到的理论研究结果,在2,1,3-苯并噻二唑衍生物基础上进行结构修饰得到的一系列分子可以作为有机发光二极管中的有机发光材料.     

X-Ray Topography: Yesterday,Today, and Prospects for the Future

X-ray topography is a set of X-ray diffraction techniques that make it possible to see images of defects, to determine their type and location in the volume of the crystal structure or on its surface, and to measure their main characteristics. The review discusses the possibilities, limitations, and prospects of X-ray topography methods.     

Toward Quantum Paraelectric,Paraelastic, and Paramagnetic 2D Materials

Quantum fluctuations are known to affect the finite-temperature properties of materials made out of light elements such as hydrogen and helium. More recently, it has also been realized that quantum effects may play a role on structural transformations of ferroic materials containing heavier atoms, provided the energy barrier separating two different phases is small when compared to thermal fluctuations. Herein, 2D ferroelectric and ferroelastic materials are showcased as potential candidates to experience quantum effects on their structural conformation at liquid helium temperatures. A brief literature overview of the path integral molecular dynamics approach, which could be useful for the discovery of quantum paraelectric, paraelastic, and paramagnetic behavior in 2D materials, is also provided.     

Nonlocal symmetry,optimal systems,and explicit solutions of the mKdV equation

The nonlocal symmetry of the mKdV equation is obtained from the known Lax pair; it is successfully localized to Lie point symmetries in the enlarged space by introducing suitable auxiliary dependent variables. For the closed prolongation of the nonlocal symmetry, the details of the construction for a one-dimensional optimal system are presented. Furthermore, using the associated vector fields of the obtained symmetry, we give the reductions by the one-dimensional sub-algebras and the explicit analytic interaction solutions between cnoidal waves and kink solitary waves, which provide a way to study the interactions among these types of ocean waves. For some of the interesting solutions, the figures are given to show their properties.     

Extrema statistics of Wiener-Einstein processes in one,two, and three dimensions

The maxima and first-passage-time statistics of Wiener-Einstein processes are evaluated analytically in one, two, and three dimensions. We show that the mean square maximum displacement has the same time dependence as the mean square displacement, i.e., it grows linearly with time. The ratio of the mean square maximum to the mean square displacement is shown to decrease with increasing dimensionality. We also calculate the mean first passage time for the process to attain a given absolute displacement and find that it grows as the square of the displacementand is independent of the dimensionality of the process. In addition, we evaluate the dispersion of maxima and of first passage times and discuss their dependence on dimensionality.Supported in part by the National Science Foundation under Grant CHE 75-20624.