Lifshitz Tails in Constant Magnetic Fields

We consider the 2D Landau Hamiltonian $H$ perturbed by a random alloy-type potential, and investigate the Lifshitz tails, i.e. the asymptotic behavior of the corresponding integrated density of states (IDS) near the edges in the spectrum of $H$. If a given edge coincides with a Landau level, we obtain different asymptotic formulae for power-like, exponential sub-Gaussian, and super-Gaussian decay of the one-site potential. If the edge is away from the Landau levels, we impose a rational-flux assumption on the magnetic field, consider compactly supported one-site potentials, and formulate a theorem which is analogous to a result obtained in the case of a vanishing magnetic field

Localization on quantum graphs with random vertex couplings

We consider Schr\"odinger operators on a class of periodic quantum graphs with randomly distributed Kirchhoff coupling constants at all vertices. Using the technique of self-adjoint extensions we obtain conditions for localization on quantum graphs in terms of finite volume criteria for some energy-dependent discrete Hamiltonians. These conditions hold in the strong disorder limit and at the spectral edges

Economics of Hot Water Dipping

Hot water dipping is an appropriate method to protect apples against spoilage caused by gloeosporium rot. Tests on the varieties Topaz and Ingrid Marie at the OVB Jork (Germany) have demonstrated an effective reduction of spoilage from between 80% and 92% in charges by an infection rate of 40%. The result of an intensive R&D process between 2002 and 2003 is the development of a praxis-tested big box (300 kg) dipping station. With the first Bio Dipping systems now on the market it has now been possible to analyse the economics of this process. The costs of the systems per apple farm have been calculated from the fixed capital costs for the system itself (including maintenance costs) and from the variable costs based on an average crop of 250 t gloeosporium-sensitive varieties, which would be treated with this process every season. The Return on Investment depends largely on the effectiveness of the process in reducing spoilage and on the level of infection within the crop, assuming that losses occur in storage. Based on an average effectivity of 85% and an infection rate of 10% it has been possible to calculate an amortisation within eight years. Higher levels of infection and a consistent effectivity of 85% shorten this time span significantly. The attractions of the hot water dipping process are in the opinion of the research team at the OVB Jork not merely economically convincing in terms of ROI. By reducing the levels of spoilage throughout the entire supply chain, it is for the first time possible to make a significant development in the sustainable quality management of organic apples, providing clear benefits for both consumer, trade and the grower

Control of the apple sawfly Hoplocampa testudinea Klug in organic fruit growing and possible side effects of control strategies on Aphelinus mali Haldeman and other beneficial insects

The effect of Quassia extract on eggs and larvae of the apple sawfly Hoplocampa testudinea was studied. The efficacy of this extract is mainly due to an oral toxicity to the neonate sawfly larvae. The main active ingredients, Quassin and Neoquassin, were tested separately. Wheras Quassin has a considerable efficacy also on older larvae, Neoquassin is less efficient in this case. While Quassin and Neoquassin are found in different Quassia sources in varying relations to each other and have different efficacy, they have to be considered separately in the definition of extract quality by the content of active ingredients. These findings mean, that the “egg maturity” is not important for application date. Nevertheless, the application must take place before the larvae hatch. It was shown that low rates of Quassin (4-6 g/ha) can show very good results in the field, in other cases the rates necessary for good efficacy are much higher. This corresponds to farmers experience. Several factors as application technique and the condition of the blossom must be taken in consideration and will be object of further studies. The side effects of Quassin, Neoquassin and Quassia extract on Aphelinus mali and other beneficial arthropods were tested. Quassia is harmless to all organisms tested

Untersuchungen und Prozessbegleitung zur Praxiseinführung von Heißwassertauchanlagen im ökologischen Kernobstanbau

In general, organic grown apples (Malus x domestica Borkh.) are not treated with chemical fungicides to prevent storage decay and these fruits may suffer up to 30% decay during storage. Preliminary experiments had shown that hot water dipping of apples may be an alternative. To inhibit Gloeosporium rot (Pezicula alba, P. malicortis) water temperature may be of about 50°C and dipping time from 60 sec up to 180 sec. The present investigation was conducted to test different ranges of temperatures and dipping time periods in different apple cultivars over a three year investigation. The objective was to determinate the suitable hot water treatment that prevents decay incidence and maintains fruit quality (firmness, scale symptoms). For the reduction of post harvest decay the treatment 53°C and 180 sec is recommended; that was found suitable for `Topaz`. For cultivars with a sensitivity to skin disorders dips for 120 sec or 180 sec are recommended; that was found best for ´Elstar´(51°C), ´Ingrid Marie` (49°C), ´Holsteiner Cox´(51°C) und ´Boskoop´(51°C). A big box dipping machine was invented in northern Germany to improve the situation on the farms. The parameters we found in the trails were used as standards on the developing side. Today’s ma-chine runs with a precision temperature range of one K inside the box

Regulierung der Apfelsägewespe im Ökologischen Obstbau und Nebenwirkungen der Strategien auf die Blutlauszehrwespe

The effects of Quassia extract on eggs and larvae of the apple sawfly Hoplocampa testudinea were studied in the laboratory. The efficacy of this extract was mainly due to an oral toxicity to neonate sawfly larvae. The main active ingredients, Quassin and Neoquassin, were tested sepa-rately as pure substances. While Quassin had a considerable efficacy also on older larvae, Neo-quassin was less efficient in this case. Since Quassin and Neoquassin were found in different Quassia sources in varying relations to each other and had different efficacy, they have to be considered separately in the definition of extract quality by the content of active ingredients. This requires the application of Quassia extracts before larval hatch. It was shown that low concentra-tions of Quassin (4-6 g/ha) can achieve very good control in the field, in other cases the concentra-tions for good efficacy are much higher. These varying results seem to be connected with applica-tion technique and application date. Trials in 2004 showed that the best way of application is with plenty of water (500 to 1000 l/ha) and the best date is during the stage when blossom is fading. The side effects of Quassin, Neoquassin and Quassia extract on Aphelinus mali and other benefi-cial arthropods were tested. Quassia is harmless to all organisms tested

Depletion of T cells via Inducible Caspase 9 Increases Safety of Adoptive T-Cell Therapy Against Chronic Hepatitis B

T-cell therapy with T cells that are re-directed to hepatitis B virus (HBV)-infected cells by virus-specific receptors is a promising therapeutic approach for treatment of chronic hepatitis B and HBV-associated cancer. Due to the high number of target cells, however, side effects such as cytokine release syndrome or hepatotoxicity may limit safety. A safeguard mechanism, which allows depletion of transferred T cells on demand, would thus be an interesting means to increase confidence in this approach. In this study, T cells were generated by retroviral transduction to express either an HBV-specific chimeric antigen receptor (S-CAR) or T-cell receptor (TCR), and in addition either inducible caspase 9 (iC9) or herpes simplex virus thymidine kinase (HSV-TK) as a safety switch. Real-time cytotoxicity assays using HBV-replicating hepatoma cells as targets revealed that activation of both safety switches stopped cytotoxicity of S-CAR- or TCR-transduced T cells within less than one hour. In vivo, induction of iC9 led to a strong and rapid reduction of transferred S-CAR T cells adoptively transferred into AAV-HBV-infected immune incompetent mice. One to six hours after injection of the iC9 dimerizer, over 90% reduction of S-CAR T cells in the blood and the spleen and of over 99% in the liver was observed, thereby limiting hepatotoxicity and stopping cytokine secretion. Simultaneously, however, the antiviral effect of S-CAR T cells was diminished because remaining S-CAR T cells were mostly non-functional and could not be restimulated with HBsAg. A second induction of iC9 was only able to deplete T cells in the liver. In conclusion, T cells co-expressing iC9 and HBV-specific receptors efficiently recognize and kill HBV-replicating cells. Induction of T-cell death via iC9 proved to be an efficient means to deplete transferred T cells in vitro and in vivo containing unwanted hepatotoxicity

Untersuchungen zur Regulierung von Apfelsägewespe und Blutlaus im ökologischen Obstbau

Ziel des Projekts war es, die bestehenden großen Unsicherheiten bezüglich Qualität und Terminierung, Kombinationsmöglichkeit mit anderen Präparaten sowie Nebenwirkungen auf die Blutlauszehrwespe und andere Nützlinge des traditionell zur Regulierung der Sägewespe eingesetzten Quassiaholzauszuges auszuräumen. Des weiteren sollten mögliche Managementstrategien für eine Förderung der Blutlauszehrwespe auf ihre Praxistauglichkeit überprüft und gegebenenfalls optimiert werden. Folgende Erkenntnisse wurden aus dem Projekt gewonnen und sind für die Praxis relevant: - Quassia wirkt vor allem auf die Larven der Apfelsägewespe. Wichtig ist daher, dass Quassia ausgebracht wird, bevor die ersten Larven schlüpfen. Das Eistadium zum Ausbringtermin ist nicht von Bedeutung, die Eier müssen auch nicht direkt getroffen werden (d.h. eine Ausbringung kann, wenn die Blüte offen ist, auch vor Ende der Eiablage erfolgen). - Die wichtigsten aktiven Inhaltsstoffe Quassin und Neoquassin wirken unterschiedlich stark: Besonders bei älteren Larven ist die Wirkung von Neoquassin schlechter. Sie lässt sich auch durch eine höhere Aufwandmenge nicht verbessern. - In verschiedenen Hölzern waren Quassin und Neoquassin in unterschiedlichem Verhältnis vorhanden. - Zur Beurteilung der Qualität von Quassiaholz müssen Quassin und Neoquassin daher getrennt bewertet werden (Sekundärbefall!). - Eine Empfehlung für die Selbstherstellung von Quassia mit möglichst hoher Ausbeute wurde erarbeitet. - Eine Behandlung mit Quassia-Extrakt vor starkem Regen ist wirksam. - Es gibt einerseits Hinweise, dass auch geringe Aufwandmengen schon sehr gut wirken, andererseits gibt es auch Fälle, wo erst sehr hohe Aufwandmengen (18 g/ha) eine ausreichende Wirkung zeigten. Hier sind noch weiterführende Untersuchungen notwendig, um der Praxis gesicherte Empfehlungen für den Einsatz niedrigerer Aufwandmengen geben zu können (Spritztechnik!). - Zwei Behandlungen sind wohl in den meisten Fällen nicht notwendig, es muss aber noch untersucht werden, inwieweit zweimal behandelt werden muss, wenn bei der ersten Spritzung ein Teil der Blüten noch geschlossen ist. - Die Kombination von Quassia mit NeemAzal-T/S scheint wenig sinnvoll, da Quassia auch den Sekundärbefall reduziert - Bei Quassia-Behandlungen sind im Freiland keine Nebenwirkungen auf die Blutlaus zehrwespe sowie den Gemeinen Ohrwurm, den Siebenpunkt-Marienkäfer und die Flor-fliege zu erwarten. - Die Strategie, Blutlauszehrwespen bereits im Sommer in den Anlagen zu sammeln und ins Kühllager zu bringen, ist nicht praxistauglich, da diese Tiere im Kühllager die Zeit bis zum Frühling nicht überdauern können. - Eine Induktion der Diapause und darauffolgende Lagerung früher Stadien, die im Freiland gesammelt wurden, ist auch unter den Bedingungen eines professionellen Nützlingszüchters nicht möglich, da die Temperatur bei der Eiablage bereits die Induktion der Diapause massgeblich beeinflusst, so dass mit Freilandmaterial aus dem Spätsommer fast nie eine Diapauseinduktion erreicht werden kann. - Die Nebenwirkungen weiterer im Ökologischen Obstbau verwendeter Präparate auf Blutlauszehrwespen wurden in einem ersten Versuch abgeschätzt. Bei Netzschwefel- und Kupferpräparaten kann eine starke Nebenwirkung im Freiland weitgehend ausgeschlossen werden. Bei Schwefel-Kalk-Brühe sind weitere Untersuchungen notwendig, um eine Aussage über eine mögliche Schädigung der Zehrwespen im Freiland zu ermöglichen. - Die Populationen der Blutlauszehrwespe aus verschiedenen Regionen in Deutschland, Holland und Kanada sind genetisch weitgehend homogen. Nur die holländische Population unterschied sich etwas von den anderen Herkünften. Es gibt bisher keine Hinweise auf stark unterschiedliche regionale Biotypen

CX3CR1 Polymorphisms are associated with atopy but not asthma in German children

Chemokines and their receptors are involved in many aspects of immunity. Chemokine CX3CL1, acting via its receptor CX3CR1, regulates monocyte migration and macrophage differentiation as well as T cell-dependent inflammation. Two common, nonsynonymous polymorphisms in CX3CR1 have previously been shown to alter the function of the CX3CL1/CX3CR1 pathway and were suggested to modify the risk for asthma. Using matrix-assisted laser desorption/ionization time-of-flight technology, we genotyped polymorphisms Val249Ile and Thr280Met in a cross-sectional population of German children from Munich (n = 1,159) and Dresden ( n = 1,940). For 249Ile an odds ratio of 0.77 (95% confidence interval 0.63-0.96; p = 0.017) and for 280Met an odds ratio of 0.71 ( 95% confidence interval 0.56-0.89; p = 0.004) were found with atopy in Dresden but not in Munich. Neither polymorphism was associated with asthma. Thus, amino acid changes in CX3CR1 may influence the development of atopy but not asthma in German children. Potentially, other factors such as environmental effects may modify the role of CX3CR1 polymorphisms. Copyright (c) 2007 S. Karger AG, Basel

Periodic Jacobi operator with finitely supported perturbation on the half-lattice

We consider the periodic Jacobi operator $J$ with finitely supported perturbations on the half-lattice. We describe all eigenvalues and resonances of $J$ and give their properties. We solve the inverse resonance problem: we prove that the mapping from finitely supported perturbations to the Jost functions is one-to-one and onto, we show how the Jost functions can be reconstructed from the eigenvalues, resonances and the set of zeros of S(\l)-1, where S(\l) is the scattering matrix.Comment: 29 page