358 research outputs found
"A whole way of life": ontology of culture from Raymond Williams's perspective
An overall understanding of culture, both the culture of community one lives in and the culture of communities one communicates with, seems to be important for people to live their lives under the shelter of peace. This study hands over and foregrounds what people should notice when they face with their own and other nation’s culture in order to understand it better and prevent probable problems. Knowing about the essence of one's own culture, the person can protect it while it is being attacked by other cultures. It is predicted that by being aware of all the criteria just mentioned, people can both protect their own genuine culture and communicate with other communities, with different cultures, without facing with or creating crucial problems; as a result, they can live peacefully and help the matter of globalization. The main goal of this study is to present ontology of culture through which people would be able to get how to know their own and other's cultures. This knowledge helps them to communicate properly by knowing about what aspects of culture they should focus on when facing other cultures in order not to create any crucial problem
Correlation effects and the high-frequency spin susceptibility of an electron liquid: Exact limits
Spin correlations in an interacting electron liquid are studied in the
high-frequency limit and in both two and three dimensions. The third-moment sum
rule is evaluated and used to derive exact limiting forms (at both long- and
short-wavelengths) for the spin-antisymmetric local-field factor, . In two dimensions is found to diverge as at long wavelengths,
and the spin-antisymmetric exchange-correlation kernel of time-dependent spin
density functional theory diverges as in both two and three dimensions.
These signal a failure of the local-density approximation, one that can be
redressed by alternative approaches.Comment: 5 page
Collisionless hydrodynamics for 1D motion of inhomogeneous degenerate electron gases: equivalence of two recent descriptions
Recently I. Tokatly and O. Pankratov (''TP'', Phys. Rev. B 60, 15550 (1999))
used velocity moments of a semiclassical kinetic equation to derive a
hydrodynamic description of electron motion in a degenerate electron gas.
Independently, the present authors (Theochem 501-502, 327 (2000)) used
considerations arising from the Harmonic Potential Theorem (Phys. Rev. Lett.
73, 2244 (1994)) to generate a new form of high-frequency hydrodynamics for
inhomogeneous degenerate electron gases (HPT-N3 hydrodynamics). We show here
that TP hydrodynamics yields HPT-N3 hydrodynamics when linearized about a
Thomas-Fermi groundstate with one-dimensional spatial inhomnogeneity.Comment: 17p
Local field factors in a polarized two-dimensional electron gas
We derive approximate expressions for the static local field factors of a
spin polarized two-dimensional electron gas which smoothly interpolate between
their small- and large-wavevector asymptotic limits. For the unpolarized
electron gas, the proposed analytical expressions reproduce recent diffusion
Monte Carlo data. We find that the degree of spin polarization produces
important modifications to the local factors of the minority spins, while the
local field functions of the majority spins are less affected.Comment: 8 pages, 10 figure
Metal Surface Energy: Persistent Cancellation of Short-Range Correlation Effects beyond the Random-Phase Approximation
The role that non-local short-range correlation plays at metal surfaces is
investigated by analyzing the correlation surface energy into contributions
from dynamical density fluctuations of various two-dimensional wave vectors.
Although short-range correlation is known to yield considerable correction to
the ground-state energy of both uniform and non-uniform systems, short-range
correlation effects on intermediate and short-wavelength contributions to the
surface formation energy are found to compensate one another. As a result, our
calculated surface energies, which are based on a non-local
exchange-correlation kernel that provides accurate total energies of a uniform
electron gas, are found to be very close to those obtained in the random-phase
approximation and support the conclusion that the error introduced by the
local-density approximation is small.Comment: 5 pages, 1 figure, to appear in Phys. Rev.
Correlation energy of a two-dimensional electron gas from static and dynamic exchange-correlation kernels
We calculate the correlation energy of a two-dimensional homogeneous electron
gas using several available approximations for the exchange-correlation kernel
entering the linear dielectric response of the system.
As in the previous work of Lein {\it et al.} [Phys. Rev. B {\bf 67}, 13431
(2000)] on the three-dimensional electron gas, we give attention to the
relative roles of the wave number and frequency dependence of the kernel and
analyze the correlation energy in terms of contributions from the plane. We find that consistency of the kernel with the electron-pair
distribution function is important and in this case the nonlocality of the
kernel in time is of minor importance, as far as the correlation energy is
concerned. We also show that, and explain why, the popular Adiabatic Local
Density Approximation performs much better in the two-dimensional case than in
the three-dimensional one.Comment: 9 Pages, 4 Figure
A Biased Review of Sociophysics
Various aspects of recent sociophysics research are shortly reviewed:
Schelling model as an example for lack of interdisciplinary cooperation,
opinion dynamics, combat, and citation statistics as an example for strong
interdisciplinarity.Comment: 16 pages for J. Stat. Phys. including 2 figures and numerous
reference
Active Brownian Particles. From Individual to Collective Stochastic Dynamics
We review theoretical models of individual motility as well as collective
dynamics and pattern formation of active particles. We focus on simple models
of active dynamics with a particular emphasis on nonlinear and stochastic
dynamics of such self-propelled entities in the framework of statistical
mechanics. Examples of such active units in complex physico-chemical and
biological systems are chemically powered nano-rods, localized patterns in
reaction-diffusion system, motile cells or macroscopic animals. Based on the
description of individual motion of point-like active particles by stochastic
differential equations, we discuss different velocity-dependent friction
functions, the impact of various types of fluctuations and calculate
characteristic observables such as stationary velocity distributions or
diffusion coefficients. Finally, we consider not only the free and confined
individual active dynamics but also different types of interaction between
active particles. The resulting collective dynamical behavior of large
assemblies and aggregates of active units is discussed and an overview over
some recent results on spatiotemporal pattern formation in such systems is
given.Comment: 161 pages, Review, Eur Phys J Special-Topics, accepte
The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets
This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all objects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun’s centre, equal to half of Mercury’s perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground- and space-based facilities that will allow us to address those science topics
The PHENIX Experiment at RHIC
The physics emphases of the PHENIX collaboration and the design and current
status of the PHENIX detector are discussed. The plan of the collaboration for
making the most effective use of the available luminosity in the first years of
RHIC operation is also presented.Comment: 5 pages, 1 figure. Further details of the PHENIX physics program
available at http://www.rhic.bnl.gov/phenix
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