2,841 research outputs found
Isolatedness of characteristic points at blow-up for a semilinear wave equation in one space dimension
We consider the semilinear wave equation with power nonlinearity in one space
dimension. We consider an arbitrary blow-up solution , the graph
of its blow-up points and the set
of all characteristic points. We show that {\ca S} is locally finite.Comment: 57 page
Blow-up behavior outside the origin for a semilinear wave equation in the radial case
We consider the semilinear wave equation in the radial case with conformal
subcritical power nonlinearity. If we consider a blow-up point different from
the origin, then we exhibit a new Lyapunov functional which is a perturbation
of the one dimensional case and extend all our previous results known in the
one-dimensional case. In particular, we show that the blow-up set near non-zero
non-characteristic points is of class , and that the set of characteristic
points is made of concentric spheres in finite number in for any .Comment: 21 page
Horticultural markets promote alien species invasions : an Estonian case study of herbaceous perennials
Gardening is a popular pastime, but commercial horticulture is responsible for the introduction of alien species and contributes to invasions in a variety of ways. Although an extensive international literature is available on plant invasions, it is still important at the national level to examine the influence of local factors. Accordingly, 17 nurseries in Estonia that cultivated and sold perennial alien species were selected, and a list of species and prices was compiled. The relationships between species status, and factors such as their abundance in the wild were examined statistically. A qualitative list of the nationally problematic species among herbaceous perennials was also completed. A total of 880 taxa were recorded, of which 10.3% were native and 89.7% alien. In all, 87.3% of the alien species were still confined to cultivated areas. The ecological and socio-economic characteristics of the taxa were described, and lists of the families of casual, naturalised and invasive aliens were provided. Both native and increasing wild alien species have a very similar profile on the market. Alien species that are less expensive, widely available and have more cultivars per species on the market are also more likely to escape. The invasive status and abundance of escaped aliens in an area increases with residence time. In general, socio-economic factors create new and reflect previous propagule pressures from commercial horticulture, which continuously increase the likelihood of alien species surviving and invading new areas. Our findings suggest that these national socioeconomic market-related factors explain much of the invasiveness of various perennial ornamental species, and therefore regional and national authorities urgently need to regulate and control the ornamental plant trade to diminish the risk of new invasions
Thermal rearrangements in the tetra-arylcyclopropene series
The literature provides many examples of thermal
rearrangements of small-ring compounds to yield
systems involving less bond-angle strain. In the
arylcyclopropene series these involve, in many
cases, fairly complex pathways, and only formalized
mechanisms have been suggested
Reliability analysis of dynamic systems by translating temporal fault trees into Bayesian networks
Classical combinatorial fault trees can be used to assess combinations of failures but are unable to capture sequences of faults, which are important in complex dynamic systems. A number of proposed techniques extend fault tree analysis for dynamic systems. One of such technique, Pandora, introduces temporal gates to capture the sequencing of events and allows qualitative analysis of temporal fault trees. Pandora can be easily integrated in model-based design and analysis techniques. It is, therefore, useful to explore the possible avenues for quantitative analysis of Pandora temporal fault trees, and we identify Bayesian Networks as a possible framework for such analysis. We describe how Pandora fault trees can be translated to Bayesian Networks for dynamic dependability analysis and demonstrate the process on a simplified fuel system model. The conversion facilitates predictive reliability analysis of Pandora fault trees, but also opens the way for post-hoc diagnostic analysis of failures
Why a splitting in the final state cannot explain the GSI-Oscillations
In this paper, I give a pedagogical discussion of the GSI anomaly. Using two
different formulations, namely the intuitive Quantum Field Theory language of
the second quantized picture as well as the language of amplitudes, I clear up
the analogies and differences between the GSI anomaly and other processes (the
Double Slit experiment using photons, scattering, and
charged pion decay). In both formulations, the conclusion is reached that the
decay rate measured at GSI cannot oscillate if only Standard Model physics is
involved and the initial hydrogen-like ion is no coherent superposition of more
than one state (in case there is no new, yet unknown, mechanism at work).
Furthermore, a discussion of the Quantum Beat phenomenon will be given, which
is often assumed to be able to cause the observed oscillations. This is,
however, not possible for a splitting in the final state only.Comment: 10 pages, 3 figures; matches published version (except for some
stylistic ambiguities
From Dollars to Sense: A Critique of Government Funding for the Battered Women\u27s Shelter Movement
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