3,955 research outputs found
Madex Plus and Madex I12 overcome Virus Resistance of Codling Moth
Over the past three years, codling moth populations with resistance to the Mexican isolate
of Cydia pomonella Granulovirus (CpGV) have been found in Germany, France, Italy,
Switzerland and the Netherlands. Andermatt Biocontrol has tested two new virus isolates
(Madex Plus and Madex I12) which can overcome CpGV-resistance, and compared them
in the field. Both isolates proved effective against Mexican isolate resistant codling moth
populations, in several locations. In Switzerland, Madex Plus has been already approved
for use
Logarithmic two-Point Correlation Functions from a z = 2 Lifshitz Model
The Einstein-Proca action is known to have asymptotically locally Lifshitz
spacetimes as classical solutions. For dynamical exponent z=2, two-point
correlation functions for fluctuations around such a geometry are derived
analytically. It is found that the retarded correlators are stable in the sense
that all quasinormal modes are situated in the lower half-plane of complex
frequencies. Correlators in the longitudinal channel exhibit features that are
reminiscent of a structure usually obtained in field theories that are
logarithmic, i.e. contain an indecomposable highest weight representation. This
suggests the model at hand as a candidate for a gravity dual of a logarithmic
field theory with anisotropic scaling symmetry.Comment: 31 pages, 2 figure
Wirkung des Quassiapräparates "Quassan" gegen die Sägewespe
Since reduction in effectivity of the bitter wood preparation Quassan in the years 1999 and 2000, the quality of the product had to be criticised. Quality control has since been improved, in so far as each batch is now tested in a biotest on aphids before dispatch. Parallel to its normal use in the field, the effect of Quassan was also field tested in 2001 against apple sawflies. Quassan was tested in different concentrations per hectare and the effect compared with an untreated control as well as with plots treated with a self-cooked Quassiawood extract. All the methods showed an efficacy of 80% or more as compared with the control. Differences due to concentration per hectare used were only minimal
Analogue Gravity Models From Conformal Rescaling
Analogue gravity is based on a mathematical identity between quantum field
theory in curved space-time and the propagation of perturbations in certain
condensed matter systems. But not every curved space-time can be simulated in
such a way, because one does not only need a condensed matter system that
generates the desired metric tensor, but that system then also has to obey its
own equations of motion. And specifying the metric tensor that one wishes to
realize usually overdetermines the underlying condensed matter system, such
that its equations of motion are in general not fulfilled, in which case the
desired metric does not have an analogue.
Here, we show that the class of metrics that have an analogue is bigger than
what a first cursory consideration might suggest. This is due to the analogue
metric only being defined up to a choice of parametrization of the perturbation
in the underlying condensed matter system. In this way, the class of analogue
gravity models can be vastly expanded. In particular, we demonstrate how this
freedom of choice can be used to insert an intermediary conformal factor. Then,
as a corollary, we find that any metric conformal to a Painlev\'e--Gullstrand
type line element can, potentially, result as an analogue of a perturbation
propagating in a non-viscous, barotropic fluid.Comment: 12 page
Holographic Response of Electron Clouds
In order to make progress towards more realistic models of holographic
fermion physics, we use gauge/gravity duality to compute the dispersion
relations for quasinormal modes and collective modes for the electron cloud
background, i.e. the non-zero temperature version of the electron star. The
results are compared to the corresponding results for the Schwarzschild and
Reissner-Nordstr\"om black hole backgrounds, and the qualitative differences
are highlighted and discussed.Comment: 27 page
Summation-By-Parts Operators and High-Order Quadrature
Summation-by-parts (SBP) operators are finite-difference operators that mimic
integration by parts. This property can be useful in constructing energy-stable
discretizations of partial differential vequations. SBP operators are defined
by a weight matrix and a difference operator, with the latter designed to
approximate to a specified order of accuracy. The accuracy of the weight
matrix as a quadrature rule is not explicitly part of the SBP definition. We
show that SBP weight matrices are related to trapezoid rules with end
corrections whose accuracy matches the corresponding difference operator at
internal nodes. The accuracy of SBP quadrature extends to curvilinear domains
provided the Jacobian is approximated with the same SBP operator used for the
quadrature. This quadrature has significant implications for SBP-based
discretizations; for example, the discrete norm accurately approximates the
norm for functions, and multi-dimensional SBP discretizations
accurately mimic the divergence theorem.Comment: 18 pages, 3 figure
Holographic Plasmons
Since holography yields exact results, even in situations where perturbation
theory is not applicable, it is an ideal framework for modeling strongly
correlated systems. We extend previous holographic methods to take the
dynamical charge response into account and use this to perform the first
holographic computation of the dispersion relation for plasmons. As the
dynamical charge response of strange metals can be measured using the new
technique of momentum-resolved electron energy-loss spectroscopy (M-EELS),
plasmon properties are the next milestone in verifying predictions from
holographic models of new states of matter.Comment: 12 pages, 2 figures. v2: Minor changes v3: Minor adjustments v4:
Published versio
A direct procedure for interpolation on a structured curvilinear two-dimensional grid
A direct procedure is presented for locally bicubic interpolation on a structured, curvilinear, two-dimensional grid. The physical (Cartesian) space is transformed to a computational space in which the grid is uniform and rectangular by a generalized curvilinear coordinate transformation. Required partial derivative information is obtained by finite differences in the computational space. The partial derivatives in physical space are determined by repeated application of the chain rule for partial differentiation. A bilinear transformation is used to analytically transform the individual quadrilateral cells in physical space into unit squares. The interpolation is performed within each unit square using a piecewise bicubic spline
Regulierung der Blutlaus (Eriosoma lanigerum) im Biologischen Apfelbau. Erfahrungen aus drei Versuchsjahren mit direkten und indirekten Verfahren
Einleitung
1997 trat die Blutlaus (Eriosoma /anigerum) in der Schweiz in verschiedenen Bioobstanlagen stark auf. Die Gründe dafür liegen wahrscheinlich in der ungenügenden Parasitisierung der Blutläuse durch die Blutlauszehrwespe. Zwei kalte Winter (1995/96 und 1996/97) aber auch die kühle und nasse Witterung im Mai und Juni 1997 haben die Entwicklung der Zehrwespenpopulationen stark eingeschränkt. Die Schaden waren vielfach enorm und führten nebst Fruchtverschmutzungen zu irreversiblen Trieb- und Knospenschaden, gefolgt von Ernteausfall im Folgejahr, bis zum Absterben ganzer Baume. Die Praktiker begegneten dem Übel mit Mineralölbehandlungen, Entfernung der Kolonien durch Abbürsten bzw. mit einem Hochdruck-Wasserstrahl oder mit viel Geduld für den Aufbau von Nützlingen wie Zehrwespe und Ohrwürmer. Der akuten Lage entsprechend führte das FiBL unter Mitwirkung der Firma Andermatt Biocontrol AG Versuche mit direkten und indirekten Maßnahmen durch
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