4,220 research outputs found
Local inverse scattering at fixed energy in spherically symmetric asymptotically hyperbolic manifolds
In this paper, we adapt the well-known \emph{local} uniqueness results of
Borg-Marchenko type in the inverse problems for one dimensional Schr{\"o}dinger
equation to prove \emph{local} uniqueness results in the setting of inverse
\emph{metric} problems. More specifically, we consider a class of spherically
symmetric manifolds having two asymptotically hyperbolic ends and study the
scattering properties of massless Dirac waves evolving on such manifolds. Using
the spherical symmetry of the model, the stationary scattering is encoded by a
countable family of one-dimensional Dirac equations. This allows us to define
the corresponding transmission coefficients and reflection
coefficients and of a Dirac wave having a fixed
energy and angular momentum . For instance, the reflection
coefficients correspond to the scattering experiment in which a
wave is sent from the \emph{left} end in the remote past and measured in the
same left end in the future. The main result of this paper is an inverse
uniqueness result local in nature. Namely, we prove that for a fixed , the knowledge of the reflection coefficients (resp.
) - up to a precise error term of the form with
B\textgreater{}0 - determines the manifold in a neighbourhood of the left
(resp. right) end, the size of this neighbourhood depending on the magnitude
of the error term. The crucial ingredients in the proof of this result are
the Complex Angular Momentum method as well as some useful uniqueness results
for Laplace transforms.Comment: 24 page
Understanding earwig phenology in top fruit orchards
Earwigs, Forficula auricularia, are key generalist predators to a variety of orchard pests.
However, numbers of earwigs have declined in both organic and IPM orchards in recent
years. Both Integrated and Organic fruit growers have tried to re-establish earwig
populations, thus far with little success. To understand earwig population dynamics and to
find measures to increase natural orchard populations, we conducted a detailed
phenological survey of earwigs in orchards. Earwigs were sampled while sheltering during
daytime in artificial refuges. They move into the trees from the third nymph stage onwards.
In most orchards, a small second brood is produced in summer, and this has a positive
impact on population size in fall. We see only minor differences in phenology between
apple and pear orchards, mainly caused by differences in alternative hiding places.
Earwigs show an inexplicable reduction in numbers at the timing of moulting into adults.
When earwig phenology is correlated with pest phenology in apple and pear, its use for
pest control of major pests is clear
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