Prevention of vole damage in organic pomiculture

Vole damage is one of the most difficult phytosanitary problems to solve in organic pomiculture. A survey conducted in 2002 among German fruit growers showed that 90 % of the farms suffered from this damage. The water vole (A. terrestris) revealed to be the main pest in 80 % of the orchards. 61 % of the farmers announced a high interest in the development of new preventive and control methods. To stop immigration of voles into orchards a mechanical barrier system was developed and tested at two study sites in Baden-Wuerttemberg and Rhineland-Palatinate. At each location barrier systems with wire mesh (mesh size 10 mm) and polyolefine-foil were installed arround two 0.7 ha study plots. Two unprotected plots were used as a control. The barriers were anchored 20 cm deep into the soil. 30 cm of the material protruded over the surface. Automatic gates were installed for the entrance of vehicles. 4 persons needed approximately one day to install a barrier around a plot with the size of 1 ha. Not only was the wire mesh cheaper than the foil, it was permeable for wind, water and small beneficial organisms. After installing the barrier systems, voles were removed from all plots. Snap trap boxes were ranged along the outside of the barriers to catch migrating voles. A total of 33 water voles and 1263 common voles (M. arvalis) were captured on both study sites from October 2002 to November 2003. During the study period a total of 5 water voles immigrated into the first control plot and 6 settled into the other plot. Four water voles entered two of the barrier protected plots by using fresh mole galleries. The other protected plots stayed free from water voles. Simultaneous to the field studies, trials in two enclosures were carried out in Muenster. The barriers kept all water voles outside the protected plots. The results showed a high efficacy of the developed barrier system

How expensive is vole damage?

Vole species, especially Arvicola terrestris and Microtus arvalis cause significant economical damage in organic pomiculture by gnawing the root system of trees. The importance of voles as pest organisms is well known. Nevertheless, the estimation of financial loss caused by voles is difficult for German fruit growers. We conducted a survey among organic fruit growers to get data on kind and amount of annual damage. Using the available publications and official statistics we calculated economical values of organic apple trees for different types of orchard processing and tree ages. Furthermore we calculated the number of trees lost due to voles in one year

Calibration of thickness-dependent k-factors for germanium X-ray lines to improve energy-dispersive X-ray spectroscopy of SiGe layers in analytical transmission electron microscopy

We show that the accuracy of energy-dispersive X-ray spectroscopy can be improved by analysing and comparing multiple lines from the same element. For each line, an effective k-factor can be defined that varies as a function of the intensity ratio of multiple lines (e.g. K/L) from the same element. This basically performs an internal self-consistency check in the quantification using differently absorbed X-ray lines, which is in principle equivalent to an absorption correction as a function of specimen thickness but has the practical advantage that the specimen thickness itself does not actually need to be measured

Intensity-intensity correlations as a probe of interferences - under conditions of none in the intensity

The different behaviour of first order interferences and second order correlations are investigated for the case of two coherently excited atoms. For intensity measurements this problem is equivalent to Young's double slit experiment and was investigated in an experiment by Eichmann et al. [Phys. Rev. Lett. 70, 2359 (1993)] and later analyzed in detail by Itano et al. [Phys. Rev. A 57, 4176 (1998)]. Our results show that in cases where the intensity interferences disappear the intensity-intensity correlations can display an interference pattern with a visibility of up to 100%. The contrast depends on the polarization selected for the detection and is independent of the strength of the driving field. The nonclassical nature of the calculated intensity-intensity correlations is also discussed.Comment: 14 pages, 2 figure

3D simulations of self-propelled, reconstructed jellyfish using vortex methods

We present simulations of the vortex dynamics associated with the self-propelled motion of jellyfish. The geometry is obtained from image segmentation of video recordings from live jellyfish. The numerical simulations are performed using three-dimensional viscous, vortex particle methods with Brinkman penalization to impose the kinematics of the jellyfish motion. We study two types of strokes recorded in the experiment1. The first type (stroke A) produces two vortex rings during the stroke: one outside the bell during the power stroke and one inside the bell during the recovery stroke. The second type (stroke B) produces three vortex rings: one ring during the power stroke and two vortex rings during the recovery stroke. Both strokes propel the jellyfish, with stroke B producing the highest velocity. The speed of the jellyfish scales with the square root of the Reynolds number. The simulations are visualized in a fluid dynamics video.Comment: 1 page, 1 figur

Angular Distribution of Photoelectrons in Three Photon Ionisation of Sodium

Druckfehler auf Seite 54

Abwehr von Wühlmausschäden im ökologischen Obstbau mit Hilfe von Migrationsbarrieren

Sowohl im integrierten als auch im ökologischen Obstbau gelingt eine dauerhafte Abwehr von Wühlmausschäden mit den zur Verfügung stehenden Mitteln nur unzureichend. Nach den Ergebnissen einer Umfrage, für die 279 Rückmeldungen ausgewertet wurden, sind 90 % der deutschen Obstbaubetriebe von Wühlmausschäden betroffen. Hauptschadensverursacher ist die Schermaus (Arvicola terrestris), die für Schäden auf 80 % der Flächen verantwortlich gemacht wird

Abwehr von Wühlmausschäden im ökologischen Obstbau

Wühlmausschäden sind weit verbreitet und gehören zu den nur schwer lösbaren Pflanzenschutzproblemen im ökologischen Landbau. Nach einer Umfrage des Institutes für Nematologie und Wirbeltierkunde der Biologischen Bundesanstalt für Land- und Forstwirtschaft (BBA), im Jahre 2002 waren 90 % der befragten Obstbaubetriebe von Wühlmausschäden betroffen. Als Hauptschadensverursacher treten vor allem die Schermaus (Arvicola terrestris ), auch große Wühlmaus genannt, und die Feldmaus ( Microtus arvalis) auf. Mit den wenigen zur Verfügung stehenden Mitteln erreicht aber nur ein Bruchteil der ökologisch wirtschaftenden Betriebe einen akzeptablen Bekämpfungserfolg. Von Wissenschaft und Industrie werden viele Anstrengungen unternommen, um bekannte Abwehrmaßnahmen zu verbessern und neue Präparate sowie Methoden zu entwickeln. Dazu werden die Lebensweise und in letzter Zeit vor allem das sehr komplexe Verhalten von Wühlmäusen intensiv untersucht. In diesem Merkblatt werden die derzeit möglichen und angewandten Bekämpfungs- und Abwehrmaßnahmen für den ökologischen Obstbau sowie deren Erfolgsaussichten vorgestellt. Verschiedene Hinweise sollen helfen, die Wühlmausabwehr effizienter zu gestalten. Das Merkblatt richtet sich in erster Linie an Obstbauern und Obstbauberater. Aber auch Baumschulbetriebe, Gemüsebauern, kommunale Einrichtungen und Gartenbesitzer werden Anregungen für die Lösung von Wühlmausproblemen finden

Single microwave photon detection in the micromaser

High efficiency single photon detection is an interesting problem for many areas of physics, including low temperature measurement, quantum information science and particle physics. For optical photons, there are many examples of devices capable of detecting single photons with high efficiency. However reliable single photon detection of microwaves is very difficult, principally due to their low energy. In this paper we present the theory of a cascade amplifier operating in the microwave regime that has an optimal quantum efficiency of 93%. The device uses a microwave photon to trigger the stimulated emission of a sequence of atoms where the energy transition is readily detectable. A detailed description of the detector's operation and some discussion of the potential limitations of the detector are presented.Comment: 8 pages, 5 figure