Versuche im niedersächsischen Öko-Obstbau 2002 - 2003

Inhaltsübersicht: • Installierung des Schorfprognose-Verfahrens RIMpro in Praxisbetrieben zur Untersuchung einer Verbesserung der Pflanzenschutzstrategie gegen den Apfelschorf (Venturia inaequales) im ökologischen Obstbau an der Niederelbe • Mechanische Bodenbearbeitung in Baumstreifen im ökologischen Apfelanbau • Blütenausdünnungsverfahren im ökologischen Kernobstbau • Nährstoffversorgung ökologisch geführter Heidelbeeren auf Moor und Sandstandorten in Niedersachsen • Die Bekämpfung der Wühlmaus im ökologischen Obstanbau • Heißwasser-Tauchverfahren zur Reduzierung von Fruchtfäulen im Nach-erntebereich des ökologischen Kernobstbau

Non-minimal coupling, boundary terms and renormalization of the Einstein-Hilbert action

A consistent variational procedure applied to the gravitational action requires according to Gibbons and Hawking a certain balance between the volume and boundary parts of the action. We consider the problem of preserving this balance in the quantum effective action for the matter non-minimally coupled to metric. It is shown that one has to add a special boundary term to the matter action analogous to the Gibbons-Hawking one. This boundary term modifies the one-loop quantum corrections to give a correct balance for the effective action as well. This means that the boundary UV divergences do not require independent renormalization and are automatically renormalized simultaneously with their volume part. This result is derived for arbitrary non-minimally coupled matter. The example of 2D Maxwell field is considered in much detail. The relevance of the results obtained to the problem of the renormalization of the black hole entropy is discussed.Comment: 14 pages, latex. More discussion added, the case of 2D Maxwell field considered in more detail

Charakterisierung des mikrobiellen Symbioms von Blutegeln

Die medizinischen Blutegel, Hirudo medicinalis und Hirudo verbana, werden wegen ihrer kurativen Wirkung in der Humanmedizin angewandt. Während des Blutsaugens injizieren sie über ihren Speichel eine Vielzahl bioaktiver, derzeit noch unbekannter Moleküle. Eine vollständige Aufklärung aller Inhaltsstoffe mit Wirkmechanismen ist für die Entwicklung von neuen Pharmaka von großem Interesse. Vor diesem Hintergrund wurden verschiedene Organe beider Arten auf ihre Besiedlung durch symbiontische Bakterien untersucht. Dazu wurden die Bakterien zunächst unter geeigneten Bedingungen kultiviert und mittels biochemischer Methoden charakterisiert. Die Identifizierung der Symbionten erfolgte durch Polymerasekettenreaktion (PCR) und Sequenzierung der 16S rDNA. Die biochemischen Tests ergaben, dass die kultivierbaren Bakterien Amylase positiv, Gram negativ und Ornithin Decarboxylase negativ sind. Mit Hilfe von datenbankgestützten Analysen der 16S rDNA-Sequenzen konnte Aeromonas veronii biovar sobria nachgewiesen werden. Hochdurchsatzsequenzierungen der gesamtgenomischen DNA des Bakteriums aus H. medicinalis zeigten deutliche Abweichungen zum Referenzgenom von Aeromonas veronii B565

Propagation of vacuum polarized photons in topological black hole spacetimes

The one-loop effective action for QED in curved spacetime contains equivalence principle violating interactions between the electromagnetic field and the spacetime curvature. These interactions lead to the dependence of photon velocity on the motion and polarization directions. In this paper we investigate the gravitational analogue to the electromagnetic birefringence phenomenon in the static and radiating topological black hole backgrounds, respectively. For the static topological black hole spacetimes, the velocity shift of photons is the same as the one in the Reissner-Nordstr\"om black holes. This reflects that the propagation of vacuum polarized photons is not sensitive to the asymptotic behavior and topological structure of spacetimes. For the massless topological black hole and BTZ black hole, the light cone condition keeps unchanged. In the radiating topological black hole backgrounds, the light cone condition is changed even for the radially directed photons. The velocity shifts depend on the topological structures. Due to the null fluid, the velocity shift of photons does no longer vanish at the apparent horizons as well as the event horizons. But the ``polarization sum rule'' is still valid.Comment: 18 pages, Revtex, no figure

Finite Element Error Analysis and Solution Stability of affine optimal control problems

We consider affine optimal control problems subject to semilinear elliptic PDEs. The results are two-fold; first, we continue the analysis of solution stability of control problems under perturbations appearing jointly in the objective functional and the PDE. For this, we consider a coercivity-type property that is common in the field of optimal control. The second result is concerned with the obtainment of error estimates for the numerical approximation for a finite element and a variational discretization scheme. The error estimates for the optimal controls and states are obtained under several conditions of different strengths that appeared recently in the context of solution stability. This includes an improvement of error estimates for the optimal controls and states under a H\"older-type growth condition

The impact of habitat structures on some small rodents in the Kalahari Thornveld (South Africa)

Because of the increasing commercial use of the savannahs and semi-arid areas of southern Africa, vegetation compositon is departing from a natural state towards areas with a dense shrub cover. Consequently, the structural character of certain habitats also changes. In this thesis, I analysed the relationships of some selected small rodents to habitat features, considering ground-dwelling rodents (Tatera leucogaster, Saccostomus campestris, Aethomys namaquensis, Gerbillurus paeba and Desmodillus auricularis) as well as an arboreal one (Thallomys nigricauda). First data are presented on the ecology and biology regarding activity pattern, habitat use, diet and basic data on population parameters

Low-Latency Hard Real-Time Communication over Switched Ethernet

With the upsurge in the demand for high-bandwidth networked real-time applications in cost-sensitive environments, a key issue is to take advantage of developments of commodity components that offer a multiple of the throughput of classical real-time solutions. It was the starting hypothesis of this dissertation that with fine grained traffic shaping as the only means of node cooperation, it should be possible to achieve lower guaranteed delays and higher bandwidth utilization than with traditional approaches, even though Switched Ethernet does not support policing in the switches as other network architectures do. This thesis presents the application of traffic shaping to Switched Ethernet and validates the hypothesis. It shows, both theoretically and practically, how commodity Switched Ethernet technology can be used for low-latency hard real-time communication, and what operating-system support is needed for an efficient implementation

Optimierung von ionischen Flüssigkeiten als selektive Zusatzstoffe in der thermischen Trenntechnik

This work presents a first consequent thermodynamic optimization of Ionic Liquids (IL) as entrainers in the distillative separation of both azeotropic aqueous and close-boiling aromatic test systems on the basis of COSMO-RS predictions. The use of this method allows for the preselection from the large pool of available IL. Thus, favorable structural variations were identified and used for tailoring IL entrainers. For the prediction of activity coefficients with COSMO-RS, the use of different conformations of the components, derived from conformational analyses, leads to varying results. The simulations showed that the influence of conformations of the volatile components and the ionic liquids depends largely on the type of the phase equilibrium, which is investigated. The approach to tailor ionic liquids as additives for separation science starts with the prediction of the activity coefficients at infinite dilution. The simulation indicated that a higher degree of branching or longer alkyl substituents on the cation, as well as a low nucleophilicity of the anion decreases both selectivity and capacity in the polar test mixture. However, COSMO-RS calculations for the non-polar mixture showed that the selection of an entrainer for this system is more difficult, because -contrarily to water containing systems- structural variations of the IL entrainer cause converse changes in selectivity and capacity: While the selectivity for toluene increases with a lower degree of branching and a shorter alkyl substituent of the cation as well as with a lower nucleophilicity of the anion, these properties decrease the capacity. In this work the most favorable IL entrainers were synthesized and the separation factor of the test systems was experimentally validated at finite dilution. Moreover, the impact of IL’s dual nature on the preselection of IL entrainers as well as on the phase behavior of IL containing systems has been investigated.Ziel dieser Arbeit ist die Klärung der Frage, in welchen Fällen sich Vertreter der ionischen Flüssigkeiten (IL) aus thermodynamischer Sicht als selektive Zusatzstoffe in der thermischen Trenntechnik einsetzen lassen sowie die Entwicklung einer Methode zur Auswahl von wirksamen ionischen Zusatzstoffen. Deshalb wird die Wirkungsweise ionischer Flüssigkeiten auf die für die Destillation und Extraktion maßgeblichen Dampf-Flüssig-Phasengleichgewichte (Vapor Liquid Equilibrium: VLE) bzw. Flüssig-Flüssig-Phasengleichgewichte (Liquid Liquid Equilibrium: LLE) für wässrige und nicht-wässrige Systeme untersucht. Hierzu sind die Phasengleichgewichte der Testsysteme Ethanol-Wasser, Tetrahydrofuran (THF)-Wasser und Methylcyclohexan (MCH)-Toluol nach Zugabe von systematisch variierten ionischen Flüssigkeiten vermessen worden. Basierend auf diesen experimentellen Daten konnte nachgewiesen werden, dass sich die quantenchemisch-thermodynamisch basierte COSMO-RS (COnductor-like Screening MOdel for Real Solvents) Vorhersagemethode, die in der kommerziell erhältlichen Software COSMOtherm implementiert wurde, für eine prädiktive und trennproblemspezifische Strukturoptimierung ionischer Flüssigkeiten eignet. Auf dieser Grundlage wurden für das polare azeotrope System THF-Wasser und für das unpolare engsiedende System MCH-Toluol mehrere geeignete IL-Entrainer identifiziert, die eine wirksame Trennung mittels Extraktivrektifikation ermöglichen. Da die COSMO-RS-Berechnung allein auf den bereitgestellten Molekül- und Ionengeometrien der an der Mischung beteiligten Komponenten beruht, beeinflussen die für die Simulation ausgewählten Konformere das a priori berechnete Phasengleichgewicht. In dieser Arbeit wurde deshalb eine Methode zur Berücksichtigung von Konformeren entwickelt, wodurch die Genauigkeit der COSMO-RS-Simulation erheblich gesteigert werden konnte. Außerdem wurden erste Screenings durchgeführt, die Indizien zur Bewertung der Stabilität von den 39 verwendeten IL in den genannten Testsystemen liefern und somit weitere Aspekte bei der Verwendung von ionischen Flüssigkeiten in thermischen Trennverfahren aufzeigen. Darüber hinaus wurde mittels einer ASPEN-PLUS-Prozesssimulation für das System Ethanol-Wasser mit dem Hilfsstoff [EMIM][BF4] eine energetische Überlegenheit des ionischen Zusatzstoffes bei der Extraktivrektifikation über den etablierten molekularen Zusatzstoff 1,2 Ethandiol nachgewiesen

New assumptions for stability analysis in elliptic optimal control problems

This paper is dedicated to the stability analysis of the optimal solutions of a control problem associated with a semilinear elliptic equation. The linear differential operator of the equation is neither monotone nor coercive due to the presence of a convection term. The control appears only linearly, or may not even appear explicitly in the objective functional. Under new assumptions, we prove Lipschitz stability of the optimal controls and associated states with respect to not only perturbations in the equation and the objective functional but also the Tikhonov regularization parameter.The first author was supported by MCIN/AEI/10.13039/501100011033/ under re-search project PID2020-114837GB-I00. The second and third authors were supported by the Aus-trian Science Foundation (FWF) under grant I457

Solution stability of parabolic optimal control problems with fixed state-distribution of the controls

The paper presents results about strong metric subregularity of the optimality mapping associated with the system of first-order necessary optimality conditions for a problem of optimal control of a semilinear parabolic equation. The control has a predefined spatial distribution and only the magnitude at any time is a subject of choice. The obtained conditions for subregularity imply, in particular, sufficient optimality conditions that extend the known ones. The paper is complementary to a companion one by the same authors, in which a distributed control is considered.Comment: arXiv admin note: substantial text overlap with arXiv:2209.0892