Effects of a low-input pesticide use on tritrophic systems in winter wheat and pea

Zahlreiche Studien belegen, dass natürliche Gegenspieler von Blattläusen (z. B. Coccinellidae, Syrphidae, Chrysopidae, Carabidae) in der Lage sind, das Blattlauswachstum einzuschränken und einen ökonomisch relevanten Massenbefall zu verhindern. Daher ist es wichtig, die Prädatoren z. B. durch reduzierte Anwendung chemischer Pflanzenschutzmittel zu schonen. Untersuchungen zeigten, dass der Verzicht von chemischen Pflanzenschutzmitteln, z. B. im Ökolandbau, und eine verringerte Intensität der Anwendung zu positiven Auswirkungen auf die natürlichen Regelmechanismen und Biodiversität in den Feldern führte (u. a. Kromp 1990, Langmaack et al. 2001). Andere Studien belegten, dass es zwischen ökologischem und konventionellem Anbau keine großen Unterschiede gab (u. a. Purtauf et al. 2005). Bislang ist offen, wie sich im Rahmen einer konventionellen Landbewirtschaftung eine durchgängige deutliche Reduzierung der Anwendung chemischer Pflanzenschutzmittel bei Erhalt der sonstigen Rahmenbedingungen langfristig auf die ökologische Situation im Feld auswirkt. Ziel der vorliegenden 3-jährigen Untersuchungen war es daher, Phänomene der langfristigen Anpassung tritrophischer Systeme und Dominanzstrukturen von Nützlingsgesellschaften an Pflanzenschutzsysteme mit um 50 % reduzierter Anwendung von Herbiziden, Fungiziden und Insektiziden anhand von geeigneten Indikatoren zu identifizieren.Long term effects of low-input compared with high-input pesticide use were investigated in a conventional farm in the Magdeburger Boerde using half-fields-comparisons from 2004-2006. Three fields were divided into two halves. One half was characterised by 50% reduced pesticide doses and the other half by good plant protection practise (100%). The effects of both strategies on tritrophic systems crop - aphids - predators were studied regarding arthropod densities and biodiversity as well as potential of natural regulation of aphids. Here, the results of one field were presented. In all three years statistically significantly more aphids and predators were found in the low-input variant than in the high-input variant after insecticide use. The abundance and biodiversity of carabids were not affected by the reduced pesticide dose. The first indication of a long term effect was detected in the form of higher weed occurrence in the low-input strategy before herbicide use. It is concluded, that aphids profit to a greater extent from the reduced level of pesticide use than do their predators. Thus, the enhanced potential of natural regulation failed to reduce aphid densities

Araneae as indicators in low-input strategies in crop protection

Ziel des Reduktionsprogramms chemischer Pflanzenschutz ist es, die Anwendung von Pflanzenschutzmitteln (PSM) auf das notwendige Maß zu begrenzen (Backhaus & al. 2005). Als geeigneter quantitativer Indikator für die Kennzeichnung der Pflanzenschutzmittel-Anwendungsintensität findet der Behandlungsindex Verwendung. Praxisstudien sollen zeigen, wie sich eine längerfristige Reduktion der Anwendung von PSM auf betrieblicher Ebene auf den ökologischen Status quo von Ackerflächen auswirkt.Reduction programs are designed to reduce chemical plant protection to a minimum. The intensity of plant protection can be measured by the treatment frequency index (BI). This study is interested in the ecological impact of a long-term reduction of chemical plant protection in commercial crop cultures. It investigates the effects of a 50 % treatment reduction on Araneae at three fields in Ochtmersleben (Saxony-Anhalt). In 2003, data collection focused on fields of winter wheat (100 % application, BI 3.5 vs. 50 % application, BI 1.9), spring wheat (100 % application, BI 4.6 vs. 50 % application, BI 0.8) and sugar beet (100 % BI 5.4 vs. 50 %, BI 2,7). In 2004, plots of winter wheat (100 %, BI 5.4 vs. 50 %, BI 3.3), spring wheat (100 %, BI 5.8 vs. 50 %, BI 4.0) and peas (100 %, BI 2.9; 50 %, BI 1.4) and in 2005: winter wheat (3.8 vs. 2.1), pea (4.1 vs. 2.2) and winter wheat (6.25 vs. 3.3) were investigated. Insecticides were applied in 2004 and 2005. In 2003-2005, 11,120 spiders belonging to 60 species out of 14 families have been documented. Activity density peaked in the 50 % variant of fields 1 - 3 (field 1: 2,373, field 2: 1,908, field 3: 1,940 spiders). It was lowest in field 3 (100 %) with 1,564 spiders. In 2003, a total of 6,951 spiders belonging to 41 species out of 12 families were caught in pitfall traps during the period 01/06/03 - 27/06/03. Activity density peaked in the 50 % variant of winter wheat with 1,427 individuals. It was lowest in both sugar beet variants (100 % variant: 891 specimens, 50 % variant: 1,074 specimen). The impact of plant protection on the spider activity was stronger when the measures were applied at an early date. The intensity of plant protection also influenced the species diversity (e.g. sugar beets 50 % variant: 15 species; 100 % variant: 10 species). In 2004, 1,341 spider individuals were collected during the period 01/06/04 - 06/07/04. The massive 80 % drop of spider activity compared to the previous year was likely due to the application of insecticides. A total of 41 species belonging to 12 families were identified. Again, Araneae activity peaked in winter wheat (650 specimen), followed by spring wheat (435 specimen) and peas (256 specimen). In 2005, a total of 2,828 individuals (Araneae) belonging to 38 species out of 9 families were identified (collecting period 08/06/05 - 06/07/05). More individuals (986) were found in winter wheat (50 %, field 1) compared to winter wheat (50 %, 659 species, field 3) and peas (50 %, 238 species, field 2). The results indicate that the impact of insecticides on the spider population was stronger the earlier insecticides were applied. In summary, a long-term reduction of chemical plant protection of 50 % did have positive effects on spider coenoses

Cloud-Computing in Banking Influential Factors, Benefits and Risks from a Decision Maker\u27s Perspective

In 2008 Gartner Group listed Cloud-Computing (CC) in its Hype-Cycle (Gartner, 2008). Since these days, enterprises in different industries discuss the utilization of cloud-computing for their own benefit. The banking industry traditionally is heavily dependent on information technology. Therefore, it can be assumed that cloud-computing could be of particular interesting for banks. This paper investigates the use of cloud-computing in German banks and the associated benefits and risks as senior management perceives them. Grounded in the TOE-Framework ten expert interviews with senior decision makers German banks have been conducted to evaluate the decision criteria pro and con cloud computing. Several factors influencing the cloud-computing decision have been detected, amongst them the technology supporting infrastructure, government regulations and security and compliance requirements. Furthermore the financial benefits came up as the most important perceived benefit and government regulation (esp. privacy/security regulations) are the most important risks perceived by senior management

Integrated quantized electronics: a semiconductor quantized voltage source

The Josephson effect in superconductors links a quantized output voltage Vout = f \cdot(h/2e) to the natural constants of the electron's charge e, Planck's constant h, and to an excitation frequency f with important applications in electrical quantum metrology. Also semiconductors are routinely applied in electrical quantum metrology making use of the quantum Hall effect. However, despite their broad range of further applications e.g. in integrated circuits, quantized voltage generation by a semiconductor device has never been obtained. Here we report a semiconductor quantized voltage source generating quantized voltages Vout = f\cdot(h/e). It is based on an integrated quantized circuit of a single electron pump operated at pumping frequency f and a quantum Hall device monolithically integrated in series. The output voltages of several \muV are expected to be scalable by orders of magnitude using present technology. The device might open a new route towards the closure of the quantum metrological triangle. Furthermore it represents a universal electrical quantum reference allowing to generate quantized values of the three most relevant electrical units of voltage, current, and resistance based on fundamental constants using a single device.Comment: 15 pages, 3 figure

A quantized current source with mesoscopic feedback

We study a mesoscopic circuit of two quantized current sources, realized by non-adiabatic single- electron pumps connected in series with a small micron-sized island in between. We find that quantum transport through the second pump can be locked onto the quantized current of the first one by a feedback due to charging of the mesoscopic island. This is confirmed by a measurement of the charge variation on the island using a nearby charge detector. Finally, the charge feedback signal clearly evidences loading into excited states of the dynamic quantum dot during single-electron pump operation

Influence of substrate dimensionality on the growth mode of epitaxial 3D-bonded GeTe thin films: From 3D to 2D growth

The pseudo-binary line of Sb2Te3-GeTe contains alloys featuring different crystalline characteristics from two-dimensionally (2D-) bonded Sb2Te3 to three-dimensionally (3D-) bonded GeTe. Here, the growth scenario of 3D-bonded GeTe is investigated by depositing epitaxial GeTe thin films on Si(111) and Sb2Te3-buffered Si(111) substrates using pulsed laser deposition (PLD). GeTe thin films were grown in trigonal structure within a temperature window for epitaxial growth of 210–270 °C on unbuffered Si(111) substrates. An unconventional growth onset was characterized by the formation of a thin amorphous GeTe layer. Nonetheless, the as-grown film is found to be crystalline. Furthermore, by employing a 2D-bonded Sb2Te3 thin film as a seeding layer on Si(111), a 2D growth of GeTe is harnessed. The epitaxial window can substantially be extended especially towards lower temperatures down to 145 °C. Additionally, the surface quality is significantly improved. The inspection of the local structure of the epitaxial films reveals the presence of a superposition of twinned domains, which is assumed to be an intrinsic feature of such thin films. This work might open a way for an improvement of an epitaxy of a 3D-bonded material on a highly-mismatched substrate (e.g. Si (111)) by employing a 2D-bonded seeding layer (e.g. Sb2Te3)

Research Update: Van-der-Waals epitaxy of layered chalcogenide Sb2Te3 thin films grown by pulsed laser deposition

An attempt to deposit a high quality epitaxial thin film of a two-dimensionally bonded (layered) chalcogenide material with van-der-Waals (vdW) epitaxy is of strong interest for non-volatile memory application. In this paper, the epitaxial growth of an exemplary layered chalcogenide material, i.e., stoichiometric Sb2Te3 thin films, is reported. The films were produced on unreconstructed highly lattice-mismatched Si(111) substrates by pulsed laser deposition (PLD). The films were grown by vdW epitaxy in a two-dimensional mode. X-ray diffraction measurements and transmission electron microscopy revealed that the films possess a trigonal Sb2Te3 structure. The single atomic Sb/Te termination layer on the Si surface was formed initializing the thin film growth. This work demonstrates a straightforward method to deposit vdW-epitaxial layered chalcogenides and, at the same time, opens up the feasibility to fabricate chalcogenide vdW heterostructures by PLD

Microstructures to control elasticity in 3D printing

We propose a method for fabricating deformable objects with spatially varying elasticity using 3D printing. Using a single, relatively stiff printer material, our method designs an assembly of small-scale microstructures that have the effect of a softer material at the object scale, with properties depending on the microstructure used in each part of the object. We build on work in the area of metamaterials, using numerical optimization to design tiled microstructures with desired properties, but with the key difference that our method designs families of related structures that can be interpolated to smoothly vary the material properties over a wide range. To create an object with spatially varying elastic properties, we tile the object's interior with microstructures drawn from these families, generating a different microstructure for each cell using an efficient algorithm to select compatible structures for neighboring cells. We show results computed for both 2D and 3D objects, validating several 2D and 3D printed structures using standard material tests as well as demonstrating various example applications