Multipole Structure Research Articles

Effect of electron irradiation on the spectra of elementary excitations in C60 fullerite

Electron irradiation produces changes in the spectra of elementary excitations of C60 fullerite, which are manifested by decrease in the π-plasmon energy, bandgap width, and energies of the HOMO-LUMO and other molecular transitions, smoothening of the corresponding spectral features, and significant growth in the quasicontinuous low-energy background intensity, the latter being indicative of an increase in the conductivity. The observed “red shifts” are related to collectivization of a part of the π electrons, the formation of chemical bonds between adjacent molecules (polymerization), and the corresponding increase in the proportion of sp3-hybridized electrons. Characteristic electron energy loss (EEL) spectra of an intact fullerite sample non-perturbed by the polymerization process were measured. The EEL spectra of fullerite exhibit a multipole structure due to the (σ + π)-plasmon and reveal an exciton feature which is highly sensitive with respect to electron irradiation and can be used to characterize the initial fullerite structure and to indicate the polymerization onset.

Evolution of Multipolar Magnetic Fields in Isolated Neutron Stars and its effect on Pulsar Radio Emission

AbstractThe evolution of the multipolar structure of the magnetic field of isolated neutron stars is studied assuming the currents to be confined to the crust. Lower orders (≤ 25) of multipole are seen to evolve in a manner similar to the dipole suggesting little or no evolution of the expected pulse shape. We also study the multifrequency polarization position angle traverse of PSR B0329+54 and find a significant frequency dependence above 2.7 GHz. We interpret this as an evidence of strong multipolar magnetic field present in the radio emission region.

Numerical Solution of Acoustic Propagation Problems Using Linearized Euler Equations

The goal of this work is to study some numerical solutions of acoustic propagation problems using linearized Eider's equations. The two-dimensional Euler's equations are linearized around a stationary mean flow. The solution is obtained by using a dispersion-relation-preserving scheme in space, combined with a fourth-order Runge-Kutta algorithm in time. This numerical integration leads to very good results in terms of accuracy, stability and low storage. The radiation of a source hi a subsonic and supersonic uniform mean flow is investigated. The numerical estimates are shown to be in excellent agreement with the analytical solutions. Next, a typical problem in jet noise is considered, the propagation of acoustic waves in a sheared mean flow, and the numerical solution compares favorably with ray tracing. The final goal of this work is to improve and to validate the Stochastic Noise Generation and Radiation (SNGR) model. In this model, the turbulent velocity field is modeled by a sum of random Fourier modes through a source term in the linearized Euler's equations. The implementation of acoustic sources in the linearized Euler's equations is thus an important point. This is discussed with emphasis on the ability of the method to describe correctly the multipolar structure of aeroacoustic sources. Finally, a nonlinear formulation of Euler's equations is solved hi order to limit the growth of instability waves excited by the acoustic source terms.

Local Emitters in the Regime of Maximum Absorption

Local emitters of waves (or local actuators of dimensions much less than the wavelength of the wave to be controlled) present a necessary part of most of active control systems. This paper is devoted to some properties of emitters (local emitters at most) in the regime of maximum (resonance-like) absorption. Such an emitter has an absorbing cross-section with dimensions about the wavelength of the wave to be absorbed. This property is referred to the waves of different physical nature, emitters of different constructions, different multipolarity, boundary problems of different geometrical dimension (n=2 and n=3). Especially the local 3-dimensional antennas of simple multipole structure, could ensure the absorbing cross-section unbounded, growing at the increasing of multipolarity order, remaining physically local. Regime of maximum absorption is formulated both in spectral and temporal representations in terms of so called generalized forces and velocities referred to some oscillatory degrees of freedom of boundary problem considered. Some aspects of cooperative and individual strategy of absorbing emitters and problems of their stability and causality of control are considered. Examples when emitters could help or oppose each other are shown.

Evolution of the multipolar magnetic field in isolated neutron stars

The evolution of the multipolar structure of the magnetic field of isolated neutron stars is studied assuming the currents to be confined to the crust. We find that, except for multipoles of very high order (l>25), the evolution is similar to that of a dipole. Therefore no significant evolution is expected in the pulse shape of isolated radio pulsars because of the evolution of the multipole structure of the magnetic field.

On the gravitational field of static and stationary axial symmetric bodies with multi-polar structure

We give a physical interpretation to the multi-polar Erez-Rozen-Quevedo solution of the Einstein equations in terms of bars. We find that each multi-pole corresponds to the Newtonian potential of a bar with linear density proportional to a Legendre polynomial. We use this fact to find an integral representation of the function. These integral representations are used in the context of the inverse scattering method to find solutions associated with one or more rotating bodies each with their own multi-polar structure.

Boosted static multipole particles as sources of impulsive gravitational waves

It is shown that the known solutions for nonexpanding impulsive gravitational waves generated by null particles of arbitrary multipole structure can be obtained by boosting the Weyl solutions describing static sources with arbitrary multipole moments, at least in a Minkowski background. We also discuss the possibility of boosting static sources in (anti-) de Sitter backgrounds, for which exact solutions are not known, to obtain the known solutions for null multipole particles in these backgrounds.

Impulsive waves in de Sitter and anti-de Sitter spacetimes generated by null particles with an arbitrary multipole structure

We describe a class of impulsive gravitational waves which propagate either in a de Sitter or an anti-de Sitter background. They are conformal to impulsive waves of Kundt's class. In a background with positive cosmological constant they are spherical (but non-expanding) waves generated by pairs of particles with arbitrary multipole structure propagating in opposite directions. When the cosmological constant is negative, they are hyperboloidal waves generated by a null particle of the same type. In this case, they are included in the impulsive limit of a class of solutions described by Siklos that are conformal to pp-waves.

The Varying Multipolar Structure of the Sun's Magnetic Field and the Evolution of the Solar Magnetosphere Through the Solar Cycle

The Sun's magnetic field extends far from the photosphere, into the corona, defining a magnetically dominated region before being drawn out radially by the solar wind flow. This region, where the internal sources of the solar field dominate the plasma structures and the energetic particle movement, can be properly considered the solar magnetosphere. The magnetic field in this region can be approximately described by models that extrapolate photospheric magnetic field observations under some simplifying assumptions. In this paper we use a potential field model which describes the solar field up to a source surface at 3.25 Rs, where the field is constrained to become radial. We present the variation of the magnitude and inclination of the various multipolar components throughout the solar magnetic cycle that characterise the changes in the structure of the solar magnetosphere over a period of 22 years. We also present some 3-D images of the coronal magnetic structure to show the global evolution of the solar magnetosphere throughout the solar cycle and discuss the importance of taking this structure into account in order to relate interplanetary and solar features.

Null multipole particles as sources of pp-waves

We describe a class of impulsive gravitational pp-waves generated by null particles, each of which have an arbitrary multipole structure. The nature of each point source is described for all possible modes.

Electrostatic equilibrium of two spherical charged masses in general relativity

Approximate solutions representing the gravitational - electrostatic balance of two arbitrary point sources in general relativity have led to contradictory arguments in the literature with respect to the condition of balance. Up to the present time, the only known exact solutions which can be interpreted as the nonlinear superposition of two spherically symmetric (Reissner - Nordström) bodies without an intervening strut have been for critically charged masses, . In the present paper, an exact electrostatic solution of the Einstein - Maxwell equations representing the exterior field of two arbitrary charged Reissner - Nordström bodies in equilibrium is studied. The invariant physical charge for each source is found by direct integration of Maxwell's equations. The physical mass for each source is defined invariantly in a manner similar to the way in which the charge was found. It is shown through numerical methods that balance without tension or strut can occur for non-critically charged bodies. It is demonstrated that other authors have not identified the correct physical parameters for the mass and charge of the sources. Further properties of the solution, including the multipole structure and comparison with other parametrizations, are examined.

Propagation of light in the stationary field of multipole gravitational lens

A rigorous mathematical formalism for calculating the propagation of light rays in the stationary post-Newtonian field of an isolated celestial body (or system of bodies) considered as a gravitational lens having a complex multipole structure is developed. Symmetric trace-free tensors are used in the definition of gravitational multipoles instead of the less convenient (in general situations) scalar and vector spherical harmonics. Two types of perturbations of light rays, caused correspondingly by the mass and spin multipoles, are analyzed in full detail. A new simple method of integration for the equations of light propagation is proposed. This method enables us for the first time to obtain complete expressions both for the relativistic time delay and for the angle of the total deflection of light in any order of multipole perturbations without restriction. The results thus obtained can be applied to the interpretation of the secondary weak gravitational lens effects produced by the solar system bodies, stars, binary pulsars, and galaxies where the influence of higher-order multipoles on the propagation of null rays may be important and measurable. The methods developed in the paper can be also applied to physical optics of multipole electromagnetic lenses and for calculation of propagation of gravitational waves through the curved space–time. As a particular application of the method the generalized equation for a multipole gravitational lens is derived using Cartesian coordinates and symmetric transverse-traceless tensors.

Influence of the multipolar magnetic field configuration on the density of distributed electron cyclotron resonance plasmas

In distributed electron cyclotron resonance plasma sources, the acceleration of electrons is produced by microwave electric fields, applied and distributed close to a multipolar magnetic field structure, providing along the magnets the condition for electron cyclotron resonance. The ensuing fast electrons are trapped in the multipolar magnetic field and drift along the magnets, hence the interest of a closed magnetic configuration to avoid losses at the boundaries of the confinement structure. The performances of two cylindrical reactors fed with microwave power through eight linear applicators and surrounded by either eight magnet bars or eight racetracks (magnetron-like magnetic structures) are measured and compared. In both cases plasma density saturates at the critical density, but in the case of the closed magnetic configuration the saturation is reached for a microwave input power a factor of ten lower than with the open magnetic configuration. This result confirms that the confinement effect of the multipolar magnetic field mainly applies to the fast electrons which generate the plasma.

室蘭における鉄鋼業地域社会の内部構造とその発達過程

This study attempts to identify internal formation processes of the Muroran steel industrial community by complex steel mills in Hokkaido, the first iron-works of private enterprise in Japan.It then constracts an internal formation process of single manufacturing communities by comparing Muroran with the Kamaishi iron mining-manufacturing region in Iwate Prefecture, the Ube coal mining-manufacturing region in Yamaguchi Prefecture, and the Hitachi copper mining-electrical manufacturing region in Ibaraki Prefecture.The results of the study are summarized as follows.1) Internal formation processes of the Muroran steel industrial community has lead to the following results.1. Muroran started its business as a modern steel industry. Manufacturing community of the Nippon Steel Works consists of a company community and the surrounding affiliated community. A company community of the Nippon Steel Works formed a unipolar concentric zonal structure, in which a productive, a commercial service, and a residential functions were located around the office. The Muroran ironworks formed manufacturing community of a unipolar zonal structure. A unipolar concentric zonal structure corresponds with the cases of Kamaishi, Ube and Hitachi.2. Muroran formed manufacturing city of multipolar zonal structure with two company communities.3. When the system of making steel from are in the same plant was introduced, the Muroran iron works community grew into twice the size while maintaining a unipolar concentric zonal structure. It is termed an expanded unipolar concentric zonal structure. Muroran formed manufacturing city of a multi-expanded polar concentric zonal structure with two company communities.4. A expanded polar concentric zonal structure of the Muroran iron works grew and included a unipolar concentric zonal structure of the Nippon Steel Works. It is formed a core concentric zonal structure. By the enlargement of a productive functions, commercial service and residential districts was spread into the surrounding community. As a result, Muroran formed large manufacturing city of a core concentric zonal structure.5. The steel industry declined. But residential districts was expand into the surrounding community, because both employees and retired peoples established their own houses on the outskirts, resulting in the expansion of urbanized area. The affiliated community on the central lowland grew into the Central Business District. Muroran formed city.6. The above analyses lead to an internal structure model of the Muroran single miningmanufacturing community as proposed in Fig. 5.2) The comparison of Muroran with the Kamaishi, Ube and Hitachi has lead to the following results.1. Whereas Ube and Hitachi have developed from a unipolar to a multipolar and to a core concentric zonal structure, steel industry communities experienced different stages. Kmaishi, restricted by topographical features, stays in a unipolar concentric zonal structure, Whereas Muroran with a enough space developed from a unipolar to a core concentric zonal structure.2. A expanded polar concentric zonal structure was caused by the establishment of the system to produce steel from ore in the same plant. This structure shares an essentially same character with a unipolar concentric zonal structure. Therefore, general internal formation process of single manufacturing communities developed basically from a unipolar concentric zonal structure, to a multipolar and to a core concentric zonal structure.3. The internal formation process model of a single manufacturing community by complex steel mills is proposed in Fig. 6.4. An internal formation process of a single manufacturing community by a steel industry is summarized into Fig. 7-A, while the model of complex steel mills is proposed in Fig. 7-B.

Comparative, in vitro, studies of hippocampal tissue from homing and non-homing pigeon

The purpose of this research was to characterize morphologically and electrophysiologically tissue slices obtained from the hippocampus of homing and non-homing pigeons. When hippocampal slices from the brain of homing and non-homing pigeons are observed under the dissecting microscope, diffuse fiber paths can be seen. These fiber pathways appeared to be identical with the medial fiber tract (VM) previously described histologically in the hippocampus of homing pigeon. Visualization of these tracts in living slices allowed placement of stimulating and recording electrodes in corresponding locations in these slices in both homing and non-homing pigeons. Extracellular potentials recorded from VM regions of the brains of both homing and non-homing pigeons were sensitive to CNQX indicating that glutamate may be a neurotransmitter in this area of pigeon hippocampus. These potentials could undergo long-term potentiation (LTP) following high frequency stimulation. This LTP was blocked by NMDA receptor antagonist APV in the hippocampus of homing pigeon, but was APV-resistant in the hippocampus of non-homing pigeon. Extracellular potentials from the hippocampus of homing pigeons were increased in amplitude when slices were perfused with Mg 2+-free Ringer, while potentials recorded from hippocampal slices from non-homing pigeons were unaffected by Mg 2+-free solutions. Intracellular recordings from the hippocampal slices of homing pigeons revealed that about half the cells demonstrated excitatory synaptic potentials evoked by extracellular stimulation. The EPSP was sometimes large enough to trigger an action potential. Neurons filled with the fluorescent dye, Lucifer Yellow, in the hippocampus of homing pigeons showed multipolar structure. The response of these cells to extracellular stimulation provides the activity responsible for the extracellular potentials which can undergo LTP.

Comparative, in vitro, studies of hippocampal tissue from homing and non-homing pigeon

The purpose of this research was to characterize morphologically and electrophysiologically tissue slices obtained from the hippocampus of homing and non-homing pigeons. When hippocampal slices from the brain of homing and non-homing pigeons are observed under the dissecting microscope, diffuse fiber paths can be seen. These fiber pathways appeared to be identical with the medial fiber tract (VM) previously described histologically in the hippocampus of homing pigeon. Visualization of these tracts in living slices allowed placement of stimulating and recording electrodes in corresponding locations in these slices in both homing and non-homing pigeons. Extracellular potentials recorded from VM regions of the brains of both homing and non-homing pigeons were sensitive to CNQX indicating that glutamate may be a neurotransmitter in this area of pigeon hippocampus. These potentials could undergo long-term potentiation (LTP) following high frequency stimulation. This LTP was blocked by NMDA receptor antagonist APV in the hippocampus of homing pigeon, but was APV-resistant in the hippocampus of non-homing pigeon. Extracellular potentials from the hippocampus of homing pigeons were increased in amplitude when slices were perfused with Mg2+-free Ringer, while potentials recorded from hippocampal slices from non-homing pigeons were unaffected by Mg2+-free solutions. Intracellular recordings from the hippocampal slices of homing pigeons revealed that about half the cells demonstrated excitatory synaptic potentials evoked by extracellular stimulation. The EPSP was sometimes large enough to trigger an action potential. Neurons filled with the fluorescent dye, Lucifer Yellow, in the hippocampus of homing pigeons showed multipolar structure. The response of these cells to extracellular stimulation provides the activity responsible for the extracellular potentials which can undergo LTP.

Comparing GATT and GATS: Regime creation under and after hegemony

Abstract This article makes a comparison between the General Agreement on Trade in Services (GATS), that came into force in 1995, and the General Agreement on Tariffs and Trade (GATT) of 1947. It compares regime creation under and after alleged US hegemony and the analysis concentrates on US considerations. It shows that the shift from a hegemonic to a multipolar power structure has affected both the form and content of GATS, as compared to GATT. A change of emphasis from diffuse towards specific reciprocity can be noted. This has resulted in a weakening of the principle of non‐discrimination, as embodied in the rules on most‐favored‐nation and national treatment. In particular the US has emphasized the need to avoid free riders under GATS. The new power structure has led regime leaders to develop new methods of international cooperation in the field of trade, such as the search for liberalizing commitments from a ‘critical mass’ of countries. Without such commitments the US has not been willing to make f...

Multipolar magnetic field structures for the scaling-up of high density plasmas excited in the d.c. to microwave frequency range and applicable to sputtering and chemical processing

Multipolar magnetic fields, used for the production of large areas of low pressure, high density plasmas at electron cyclotron resonance, can also be employed favourably to scale-up plasma sources at any given excitation frequency. Since fast electrons responsible for plasma excitation undergo a drift motion perpendicular to the static magnetic field of a multipolar structure, plasma production along such a structure will be uniform when the amplitude of the electric field, which accelerates the electrons, is constant along the structure and the loss of energetic electrons at the extremities of the magnets is avoided by closing the magnetic structures onto themselves according to magnetron-like configurations. The limitations to the scaling-up of sources are derived in terms of the wave propagation, wavelength, source dimensions and mean free path of the fast electrons. Other requirements in the process scale-up concern the uniform distribution of process parameters, such as gas feeding, pumping, substrate biasing and substrate heating. The use of three-dimensional magnetron structures satisfies the explicit requirements, in particular the distribution of gas supply and pumping through the excitation structure. Two examples of novel reactor configuration, designed for chemical processing and sputtering, illustrate the new concepts developed in this work.

Harmonic function expansion of nearly oblate systems

We show how to develop an expansion of nearly oblate systems in terms of a set of potential-density pairs. A harmonic (multipole) structure is imposed on the potential set at infinity, and the density can be made everywhere regular. We concentrate on a set whose zeroth order functions describe the perfect oblate spheroid of de Zeeuw (1985). This set is not bi-orthogonal, but it can be shown to be complete in a weak sense. Poisson's equation can be solved approximately by truncating the expansion of the potential in such a set. A simple example of a potential which is not one of the basis functions is expanded using the symmetric members of the basis set up to fourth order. The basis functions up to first order are reconstructed approximately using 10,000 particles to show that this set could be used as part of an $N$-body code.

Neptune radio emission in dipole and multipole magnetic fields

We study Neptune's smooth radio emission in two ways: we simulate the observations and we then consider the radio effects of Neptune's magnetic multipoles. A procedure to deduce the characteristics of radio sources observed by the Planetary Radio Astronomy experiment minimizes limiting assumptions and maximizes use of the data, including quantitative measurement of circular polarization. Study of specific sources simulates time variation of intensity and apparent polarization of their integrated emission over an extended time period. The method is applied to Neptune smooth recurrent emission (SRE). Time series are modeled with both broad and beamed emission patterns, and at two frequencies which exhibit different time variation of polarization. These dipole‐based results are overturned by consideration of more complex models of Neptune's magnetic field. Any smooth emission from the anticipated auroral radio source is weak and briefly observed. Dominant SRE originates in complex fields at midlatitude. Possible SRE source locations overlap that of “high‐latitude” emission (HLE) between +(out) and −(in) quadrupoles. This is the first identification of multipolar magnetic structure with a major source of planetary radio emission.