148 research outputs found
Ion-cyclotron turbulence and diagonal double layers in a magnetospheric plasma
A survey of current concepts regarding electrostatic ion-cyclotron turbulence (theory and experiment), and regarding inclined double potential layers in the magnetospheric plasma is presented. Anomalous resistance governed by electrostatic ion-cyclotron turbulence, and one-dimensional and two-dimensional models of double electrostatic layers in the magnetospheric plasma are examined
Magnetopause stand-off distance in dependence on the magnetosheath and solar wind parameters
International audienceA model of the magnetosheath structure proposed in a recent paper from the authors is extended to estimate the magnetopause stand-off distance from solar wind data. For this purpose, the relationship of the magnetopause location to the magnetosheath and solar wind parameters is studied. It is shown that magnetopause erosion may be explained in terms of the magnetosheath magnetic field penetration into the magnetosphere. The coefficient of penetration (the ratio of the magnetospheric magnetic field depression to the intensity of the magnetosheath magnetic field Bm?z=?Bmsin2?/2, is estimated and found approximately to equal 1. It is shown that having combined a magnetosheath model presented in an earlier paper and the magnetosheath field penetration model presented in this paper, it is possible to predict the magnetopause stand-off distance from solar wind parameters
On the history of mechanical plant "Uralets"
После победы в Великой Отечественной войне намеченный курс индустриализации страны потребовал роста добычи разных металлов, а это, в свою очередь, повлекло за собой развитие машиностроительного производства. Наиболее сложной и ответственной продукцией в 1954 году стали автобусы на шасси ГАЗ-51, которые распределялись по различным приисковым управлениям Урала и Сибири. Эти автобусы изготавливались поточным способом, хотя и в небольшом количестве до 1980 года на механическом заводе «Уралец».After the victory in the Great Patriotic War, the intended course of industrialization demanded growth of the production of various metals. All this, in turn, led to the development of machine-building production. The most complex and important products in 1954 were buses on chassis GAZ-51, which were distributed on different mine offices of the Urals and Siberia. These buses were manufactured in-line manner, although in small numbers, until 1980 at the mechanical plant "Uralets.
Temporal sampling helps unravel the genetic structure of naturally occurring populations of a phytoparasitic nematode. 1. Insights from the estimation of effective population sizes
International audienceThe sustainability of modern agriculture relies on strategies that can control the ability of pathogens to overcome chemicals or genetic resistances through natural selection. This evolutionary potential, which depends partly on effective population size (Ne), is greatly influenced by human activities. In this context, wild pathogen populations can provide valuable information for assessing the long-term risk associated with crop pests. In this study, we estimated the effective population size of the beet cyst nematode, Heterodera schachtii, by sampling 34 populations infecting the sea beet Beta vulgaris spp. maritima twice within a one-year period. Only 20 populations produced enough generations to analyze the variation in allele frequencies, with the remaining populations showing a high mortality rate of the host plant after only one year. The 20 analyzed populations showed surprisingly low effective population sizes, with most having Ne close to 85 individuals. We attribute these low values to the variation in population size through time, systematic inbreeding, and unbalanced sex- ratios. Our results suggest that H. schachtii has low evolutionary potential in natural environments. Pest control strategies in which populations on crops mimic wild populations may help prevent parasite adaptation to host resistance
A Rejoinder on Energy versus Impact Indicators
Citation distributions are so skewed that using the mean or any other central
tendency measure is ill-advised. Unlike G. Prathap's scalar measures (Energy,
Exergy, and Entropy or EEE), the Integrated Impact Indicator (I3) is based on
non-parametric statistics using the (100) percentiles of the distribution.
Observed values can be tested against expected ones; impact can be qualified at
the article level and then aggregated.Comment: Scientometrics, in pres
Dissipationless Disk Accretion
We consider disk accretion resulting purely from the loss of angular momentum
due to the outflow of plasma from a magnetized disk. In this limiting case, the
dissipation due to the viscosity and finite electrical conductivity of the
plasma can be neglected. We have obtained self-consistent, self-similar
solutions for dissipationless disk accretion. Such accretion may result in the
formation of objects whose bolometric luminosities are lower than the flux of
kinetic energy in the ejected material.Comment: 17 pages, 6 figures, published in Astronomy Reports, Vol.49, No.1,
2005, p.57 (submitted September 13, 2003). Unfortunately, we did not upload
the paper to astro-ph before, but since the topic is now of interest we feel
that the paper would benefit the communit
Long term time variability of cosmic rays and possible relevance to the development of life on Earth
An analysis is made of the manner in which the cosmic ray intensity at Earth
has varied over its existence and its possible relevance to both the origin and
the evolution of life. Much of the analysis relates to the 'high energy' cosmic
rays () and their variability due to the changing
proximity of the solar system to supernova remnants which are generally
believed to be responsible for most cosmic rays up to PeV energies. It is
pointed out that, on a statistical basis, there will have been considerable
variations in the likely 100 My between the Earth's biosphere reaching
reasonable stability and the onset of very elementary life. Interestingly,
there is the increasingly strong possibility that PeV cosmic rays are
responsible for the initiation of terrestrial lightning strokes and the
possibility arises of considerable increases in the frequency of lightnings and
thereby the formation of some of the complex molecules which are the 'building
blocks of life'. Attention is also given to the well known generation of the
oxides of nitrogen by lightning strokes which are poisonous to animal life but
helpful to plant growth; here, too, the violent swings of cosmic ray
intensities may have had relevance to evolutionary changes. A particular
variant of the cosmic ray acceleration model, put forward by us, predicts an
increase in lightning rate in the past and this has been sought in Korean
historical records. Finally, the time dependence of the overall cosmic ray
intensity, which manifests itself mainly at sub-10 GeV energies, has been
examined. The relevance of cosmic rays to the 'global electrical circuit'
points to the importance of this concept.Comment: 18 pages, 5 figures, accepted by 'Surveys in Geophysics
Impact Factor: outdated artefact or stepping-stone to journal certification?
A review of Garfield's journal impact factor and its specific implementation
as the Thomson Reuters Impact Factor reveals several weaknesses in this
commonly-used indicator of journal standing. Key limitations include the
mismatch between citing and cited documents, the deceptive display of three
decimals that belies the real precision, and the absence of confidence
intervals. These are minor issues that are easily amended and should be
corrected, but more substantive improvements are needed. There are indications
that the scientific community seeks and needs better certification of journal
procedures to improve the quality of published science. Comprehensive
certification of editorial and review procedures could help ensure adequate
procedures to detect duplicate and fraudulent submissions.Comment: 25 pages, 12 figures, 6 table
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