2,969 research outputs found
Comparison of selected submicron powder blending methods for dispersion alloys
Wet and dry blending nickel-aluminum oxide submicron powders for dispersion-strengthened alloy
Natural Slow-Roll Inflation
It is shown that the non-perturbative dynamics of a phase change to the
non-trivial phase of -theory in the early universe can give
rise to slow-rollover inflation without recourse to unnaturally small
couplings.Comment: 14 LaTex pages (3 figures available on request), UNITUE-THEP-15-199
Asymptotic freedom in a scalar field theory on the lattice
An alternative model to the trivial -theory of the standard model of
weak interactions is suggested, which embodies the Higgs-mechanism, but is free
of the conceptual problems of standard -theory. We propose a
N-component, O(N)-symmetric scalar field theory, which is originally defined on
the lattice. The model can be motivated from SU(2) gauge theory. Thereby the
scalar field arises as a gauge invariant degree of freedom. The scalar lattice
model is analytically solved in the large N limit. The continuum limit is
approached via an asymptotically free scaling. The renormalized theory evades
triviality, and furthermore gives rise to a dynamically formed mass of the
scalar particle.Comment: 10 pages, LaTeX, one figure and a motivation for the particular type
of action adde
How to include milkability in dairy cattle breeding
International audienc
Energy evolution in time-dependent harmonic oscillator
The theory of adiabatic invariants has a long history, and very important
implications and applications in many different branches of physics,
classically and quantally, but is rarely founded on rigorous results. Here we
treat the general time-dependent one-dimensional harmonic oscillator, whose
Newton equation cannot be solved in general. We
follow the time-evolution of an initial ensemble of phase points with sharply
defined energy at time and calculate rigorously the distribution of
energy after time , which is fully (all moments, including the
variance ) determined by the first moment . For example,
, and all
higher even moments are powers of , whilst the odd ones vanish
identically. This distribution function does not depend on any further details
of the function and is in this sense universal. In ideal
adiabaticity , and the variance is
zero, whilst for finite we calculate , and for the
general case using exact WKB-theory to all orders. We prove that if is of class (all derivatives up to and including the order
are continuous) , whilst for class it is known to be exponential .Comment: 26 pages, 5 figure
Adiabatic Compression of Soliton Matter Waves
The evolution of atomic solitary waves in Bose-Einstein condensate (BEC)
under adiabatic changes of the atomic scattering length is investigated. The
variations of amplitude, width, and velocity of soliton are found for both
spatial and time adiabatic variations. The possibility to use these variations
to compress solitons up to very high local matter densities is shown both in
absence and in presence of a parabolic confining potential.Comment: to appear in J.Phys.
Stationary solutions of the one-dimensional nonlinear Schroedinger equation: I. Case of repulsive nonlinearity
All stationary solutions to the one-dimensional nonlinear Schroedinger
equation under box and periodic boundary conditions are presented in analytic
form. We consider the case of repulsive nonlinearity; in a companion paper we
treat the attractive case. Our solutions take the form of stationary trains of
dark or grey density-notch solitons. Real stationary states are in one-to-one
correspondence with those of the linear Schr\"odinger equation. Complex
stationary states are uniquely nonlinear, nodeless, and symmetry-breaking. Our
solutions apply to many physical contexts, including the Bose-Einstein
condensate and optical pulses in fibers.Comment: 11 pages, 7 figures -- revised versio
Primordial Earth mantle heterogeneity caused by the Moon-forming giant impact
The giant impact hypothesis for Moon formation successfully explains the dynamic properties of the Earth–Moon system but remains challenged by the similarity of isotopic fingerprints of the terrestrial and lunar mantles. Moreover, recent geochemical evidence suggests that the Earth's mantle preserves ancient (or "primordial") heterogeneity that pre-dates the Moon-forming giant impact. Using a new hydrodynamical method, we here show that Moon-forming giant impacts lead to a stratified starting condition for the evolution of the terrestrial mantle. The upper layer of the Earth is compositionally similar to the disk, out of which the Moon evolves, whereas the lower layer preserves proto-Earth characteristics. As long as this predicted compositional stratification can at least partially be preserved over the subsequent billions of years of Earth mantle convection, a compositional similarity between the Moon and the accessible Earth's mantle is a natural outcome of realistic and high-probability Moon-forming impact scenarios. The preservation of primordial heterogeneity in the modern Earth not only reconciles geochemical constraints but is also consistent with recent geophysical observations. Furthermore, for significant preservation of a proto-Earth reservoir, the bulk major-element composition of the Earth–Moon system may be systematically shifted toward chondritic values
Anisotropy of the space orientation of radio sources. I: The catalog
A catalog of the extended extragalactic radio sources consisting of 10461
objects is compiled based on the list of radio sources of the FIRST survey. A
total of 1801 objects are identified with galaxies and quasars of the SDSS
survey and the Veron-Veron catalog. The distribution of the position angles of
the axes of radio sources from the catalog is determined, and the probability
that this distribution is equiprobable is shown to be less then 10^(-7). This
result implies that at Z equal to or smaller then 0.5, spatial orientation of
the axes of radio sources is anisotropic at a statistically significant level.Comment: 8 pages, 7 figure
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