Beitrag des ökologischen Landbaus zum Meeresumweltschutz

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Mixed cropping systems for control of weeds and pests in organic oilseed crops

Agricultural advantages of mixed cropping are gained from biological effects like light competition offering weed-suppressing capacities, or by diversification of plant covers to break development cycles of pests. These effects were measured in a two-year project on mixed cropping with organic oilseed crops. It was found that weeds can be efficiently suppressed in organic linseed (Linum usitatissivum) grown in combination with wheat (Triticum aestivum) or false flax (Camelina sativa). Linseed growth was, however, impaired. In organic pea production (Pisum sativum) also, growing the crop as a mixture with false flax led to a significant decrease of weed population. Either culture showed a balanced plant development. In winter rape (Brassica napus) there were suggestions that infestation by insect pests can be directly reduced in mixtures with cereals or legumes and that parasitoids of insect pests are supported

Development of Collembolans after coversion towards organic farming

In Northern Germany, a diverse and complex experimental farm of the Federal Agricultural Research Centre (FAL) was set-up in 2001 covering all main aspects of organic farming. Previously, the 600 ha farm had been managed conventionally. Adjacent conventional farms were used as reference. The aim of this project was to study collembolans, microbial biomass and soil organic carbon in six organically farmed fields managed as a crop rotation of six different crops compared with an adjacent conventionally managed field. We hypothesised that the specific management in organic farming promotes soil biota. Soil samples were taken during the growing season in 2004. Collembolan abundances and microbial biomass were lower under organic management, but, generally, collembolan diversity was higher in organically farmed fields combined with a shifting in the dominance structure of the species. This result reveals that, even after three years, the soil biota is still changing with management conversion

Anbau von Ölpflanzen im Mischanbau mit anderen Kulturen im ökologischen Landbau

Mischanbausysteme bieten aufgrund ihrer höheren Biodiversität auch eine höhere Pufferkapazität gegen biotischen und abiotischen Stress und weisen durch gute Ausnutzung von Standraum und Standebene eine höhere Konkurrenzkraft gegen Unkraut auf als Reinanbausysteme. Zudem kommt es zu Synergismen bei der Nährstoffaufnahme und bei der Standfestigkeit (Aufhammer, 1999; Rauber, 2001). Besonders in Systemen mit limitiertem Betriebsmittelinput, wie dem ökologischen Landbau sind diese Bestandseigenschaften interessant. Die Koppelproduktion einer Ölsaat, z. B. zur energetischen Nutzung mit der Kultur von z. B. Erbsen zur Futternutzung könnte auch eine ökonomisch und ökologische Perspektive sein, um bei ackerbaulichen Vorteilen neben Futter- oder Marktfrüchten auch nachwachsende Rohstoffe zu produzieren. Für die Tierfütterung fallen dabei zusätzlich eiweiss- und energiereiche Presskuchen an (Henkel, 1997). Seit einigen Jahren sammelt ein inzwischen als AG-Mischfruchtanbau (www.mischfruchtanbau.de) etablierter Zusammenschluss von Praktiker/innen, Berater/innen und Forscher/innen Praxiserfahrungen v. a. mit dem Mischanbau mit Leindotter (Camelina sativa). In einem Forschungsprojekt werden verschiedene Mischanbausysteme mit Ölfrüchten erprobt, deren einjährige Ergebnisse vorliegen. Mehrjährige Ergebnisse liegen aus Praxisbetrieben vor. Der Mischanbau von Ölpflanzen mit Getreide oder Körnerleguminosen ist eine beachtenswerte Möglichkeit zur Ölerzeugung für den ökologischen Landbau. Notwendig sind Untersuchungen zu optimalen Mischungsverhältnissen, zu Reihenabständen, zur Sorteneignung und zur Unkrautunterdrückung. Die Versuche werden fortgesetzt

Delta-like and gtl2 are reciprocally expressed, differentially methylated linked imprinted genes on mouse chromosome 12

AbstractThe distal portion of mouse chromosome 12 is imprinted. To date, however, Gtl2 is the only imprinted gene identified on chromosome 12. Gtl2 encodes multiple alternatively spliced transcripts with no apparent open reading frame. Using conceptuses with maternal or paternal uniparental disomy for chromosome 12 (UPD12), we found that Gtl2 is expressed from the maternal allele and methylated at the 5′ end of the silent paternal allele. A reciprocally imprinted gene, Delta-like (Dlk), with homology to genes involved in the Notch signalling pathway was identified 80kb upstream of Gtl2. Dlk was expressed exclusively from the paternal allele in both the embryo and placenta, but the CpG-island promoter of Dlk was completely unmethylated on both parental alleles. Rather, a paternally methylated region was identified in the last exon of the active Dlk allele. The proximity, reciprocal imprinting and methylation in this domain are reminiscent of the co-ordinately regulated Igf2–H19 imprinted domain on mouse chromosome 7. Like H19 and Igf2, Gtl2 and Dlk were found to be co-expressed in the same tissues throughout development, though not after birth. These results have implications for the regulation, function and evolution of imprinted domains

Dynamics of Metal Centers Monitored by Nuclear Inelastic Scattering

Nuclear inelastic scattering of synchrotron radiation has been used now since 10 years as a tool for vibrational spectroscopy. This method has turned out especially useful in case of large molecules that contain a M\"ossbauer active metal center. Recent applications to iron-sulfur proteins, to iron(II) spin crossover complexes and to tin-DNA complexes are discussed. Special emphasis is given to the combination of nuclear inelastic scattering and density functional calculations

Superconductivity and magnetic order in the non-centrosymmetric Half Heusler compound ErPdBi

We report superconductivity at $T_c = 1.22$ K and magnetic order at $T_N = 1.06$ K in the semi-metallic noncentrosymmetric Half Heusler compound ErPdBi. The upper critical field, $B_{c2}$, has an unusual quasi-linear temperature variation and reaches a value of 1.6 T for $T \rightarrow 0$. Magnetic order is found below $T_c$ and is suppressed at $B{_M} \sim 2.5$ T for $T \rightarrow 0$. Since $T_c \simeq T_N$, the interaction of superconductivity and magnetism is expected to give rise to a complex ground state. Moreover, electronic structure calculations show ErPdBi has a topologically nontrivial band inversion and thus may serve as a new platform to study the interplay of topological states, superconductivity and magnetic order.Comment: 6 pages, 5 figures; accepted for publication in Europhysics Letter

Superconducting phase diagram of the filled skuterrudite PrOs4Sb12

We present new measurements of the specific heat of the heavy fermion superconductor PrOs4Sb12, on a sample which exhibits two sharp distinct anomalies at Tc1= 1.89K and Tc2= 1.72K. They are used to draw a precise magnetic field-temperature superconducting phase diagram of PrOs4Sb12 down to 350 mK. We discuss the superconducting phase diagram of PrOs4Sb12 and its possible relation with an unconventional superconducting order parameter. We give a detailed analysis of Hc2(T), which shows paramagnetic limitation (a support for even parity pairing) and multiband effects

Conservative Quantum Computing

Conservation laws limit the accuracy of physical implementations of elementary quantum logic gates. If the computational basis is represented by a component of spin and physical implementations obey the angular momentum conservation law, any physically realizable unitary operators with size less than n qubits cannot implement the controlled-NOT gate within the error probability 1/(4n^2), where the size is defined as the total number of the computational qubits and the ancilla qubits. An analogous limit for bosonic ancillae is also obtained to show that the lower bound of the error probability is inversely proportional to the average number of photons. Any set of universal gates inevitably obeys a related limitation with error probability O(1/n^2)$. To circumvent the above or related limitations yielded by conservation laws, it is recommended that the computational basis should be chosen as the one commuting with the additively conserved quantities.Comment: 5 pages, RevTex. Corrected to include a new statement that for bosonic ancillae the lower bound of the error probability is inversely proportional to the average number of photons, kindly suggested by Julio Gea-Banacloch

Quantum Decoherence of Two Qubits

It is commonly stated that decoherence in open quantum systems is due to growing entanglement with an environment. In practice, however, surprisingly often decoherence may equally well be described by random unitary dynamics without invoking a quantum environment at all. For a single qubit, for instance, pure decoherence (or phase damping) is always of random unitary type. Here, we construct a simple example of true quantum decoherence of two qubits: we present a feasible phase damping channel of which we show that it cannot be understood in terms of random unitary dynamics. We give a very intuitive geometrical measure for the positive distance of our channel to the convex set of random unitary channels and find remarkable agreement with the so-called Birkhoff defect based on the norm of complete boundedness.Comment: 5 pages, 4 figure