175 research outputs found
11- and 22-year variations of the cosmic ray density and of the solar wind speed
Cosmic ray density variations for 17-21 solar activity cycles and the solar wind speed for 20-21 events are investigated. The 22-year solar wind speed recurrence was found in even and odd cycles. The 22-year variations of cosmic ray density were found to be opposite that of solar wind speed and solar activity. The account of solar wind speed in 11-year variations significantly decreases the modulation region of cosmic rays when E = 10-20 GeV
Dynamics of some piecewise smooth Fermi-Ulam Models
We find a normal form which describes the high energy dynamics of a class of
piecewise smooth Fermi-Ulam ping pong models; depending on the value of a
single real parameter, the dynamics can be either hyperbolic or elliptic. In
the first case we prove that the set of orbits undergoing Fermi acceleration
has zero measure but full Hausdorff dimension. We also show that for almost
every orbit the energy eventually falls below a fixed threshold. In the second
case we prove that, generically, we have stable periodic orbits for arbitrarily
high energies, and that the set of Fermi accelerating orbits may have infinite
measure.Comment: 22 pages, 4 figure
Characterization of Alternanthera mosaic virus and its Coat Protein
A new isolate of Alternanthera mosaic virus (AltMV-MU) was purified from Portulaca grandiflora plants. It has been shown that the AltMV-MU coat protein (CP) can be efficiently reassembled in vitro under different conditions into helical RNA-free virus-like particles (VLPs) antigenically related to native virus. The AltMV-MU and VLPs were examined by atomic force and transmission electron microscopies. The encapsidated AltMV-MU RNA is nontranslatable in vitro. However, it can be translationally activated by CP phosphorylation or by binding to the TGB1protein from the virus-coded movement triple gene block
Chaos, Fractals and Inflation
In order to draw out the essential behavior of the universe, investigations
of early universe cosmology often reduce the complex system to a simple
integrable system. Inflationary models are of this kind as they focus on simple
scalar field scenarios with correspondingly simple dynamics. However, we can be
assured that the universe is crowded with many interacting fields of which the
inflaton is but one. As we describe, the nonlinear nature of these interactions
can result in a complex, chaotic evolution of the universe. Here we illustrate
how chaotic effects can arise even in basic models such as homogeneous,
isotropic universes with two scalar fields. We find inflating universes which
act as attractors in the space of initial conditions. These universes display
chaotic transients in their early evolution. The chaotic character is reflected
by the fractal border to the basin of attraction. The broader implications are
likely to be felt in the process of reheating as well as in the nature of the
cosmic background radiation.Comment: 16 pages, RevTeX. See published version for fig
Collimation of a Circulating Beam in the U_70 Synchrotron by Use of Reflections in Axially - Oriented Crystals
The possibilities of the extraction and collimation of a circulating beam by
a new method due to the reflection of particles in crystals with axial
orientation were experimentally investigated in the Fall-2010 run at the U_70
synchrotron. Such crystals have positive features, because the axial potential
is five times larger than the planar potential. It has been shown that the
collimation efficiency can reach 90% due to axial effects in the crystal.
Losses of the circulating beam on a collimator have been reduced by several
times; this makes it possible to suppress the muon jet near the steel
collimator of the circulating beam.Comment: 6 pages, 7 figure
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