Definable valuations on ordered fields

We study the definability of convex valuations on ordered fields, with a particular focus on the distinguished subclass of henselian valuations. In the setting of ordered fields, one can consider definability both in the language of rings $\mathcal{L}_{\mathrm{r}}$ and in the richer language of ordered rings $\mathcal{L}_{\mathrm{or}}$. We analyse and compare definability in both languages and show the following contrary results: while there are convex valuations that are definable in the language $\mathcal{L}_{\mathrm{or}}$ but not in the language $\mathcal{L}_{\mathrm{r}}$, any $\mathcal{L}_{\mathrm{or}}$-definable henselian valuation is already $\mathcal{L}_{\mathrm{r}}$-definable. To prove the latter, we show that the value group and the ordered residue field of an ordered henselian valued field are stably embedded (as an ordered abelian group, respectively as an ordered field). Moreover, we show that in almost real closed fields any $\mathcal{L}_{\mathrm{or}}$-definable valuation is henselian.Comment: 17 page

Electrically-tunable hole g-factor of an optically-active quantum dot for fast spin rotations

We report a large g-factor tunability of a single hole spin in an InGaAs quantum dot via an electric field. The magnetic field lies in the in-plane direction x, the direction required for a coherent hole spin. The electrical field lies along the growth direction z and is changed over a large range, 100 kV/cm. Both electron and hole g-factors are determined by high resolution laser spectroscopy with resonance fluorescence detection. This, along with the low electrical-noise environment, gives very high quality experimental results. The hole g-factor g_xh depends linearly on the electric field Fz, dg_xh/dFz = (8.3 +/- 1.2)* 10^-4 cm/kV, whereas the electron g-factor g_xe is independent of electric field, dg_xe/dFz = (0.1 +/- 0.3)* 10^-4 cm/kV (results averaged over a number of quantum dots). The dependence of g_xh on Fz is well reproduced by a 4x4 k.p model demonstrating that the electric field sensitivity arises from a combination of soft hole confining potential, an In concentration gradient and a strong dependence of material parameters on In concentration. The electric field sensitivity of the hole spin can be exploited for electrically-driven hole spin rotations via the g-tensor modulation technique and based on these results, a hole spin coupling as large as ~ 1 GHz is expected to be envisaged.Comment: 8 pages, 4 figure

Henselianity in the language of rings

We consider four properties of a field K related to the existence of (de-finable) henselian valuations on K and on elementarily equivalent fields and study the implications between them. Surprisingly, the full pictures look very different in equichar- acteristic and mixed characteristic

Lokales Integrationsmanagement in Deutschland, Schweden und Frankreich: Verwaltung und Koordination im Mehrebenensystem

Im vorliegenden Band wird das lokale Integrationsmanagement in Deutschland, Frankreich und Schweden vergleichend untersucht. Im Mittelpunkt stehen Verflechtungsstrukturen, Koordination und Leistungsfähigkeit der Integrationsverwaltung mit besonderem Fokus auf den Entwicklungen nach der Flüchtlingskrise von 2015/16. Auf der Grundlage von Fallstudien und Experteninterviews in den drei Ländern wird das institutionelle Zusammenspiel von Akteuren im Mehrebenensystem und im lokalen Raum analysiert. Dabei werden jeweils die nationalen Rahmenbedingungen, lokalen Gestaltungsvarianten und krisenbedingten Herausforderungen des Integrationsmanagement kommunen- und ländervergleichend in den Blick genommen. Gestützt auf illustrative Praxisbeispiele und Tiefeneinblicke in die lokalen Handlungsprobleme leitet die Studie Lehren und Empfehlungen für eine Optimierung des Integrationsmanagements und eine krisenresilientere Verwaltungsorganisation in diesem Aufgabenbereich ab.This study analyses local integration management in Germany, France and Sweden from a comparative perspective. It focuses on the inter-administrative relations, coordination and performance of integration management, with a particular focus on developments after the refugee crisis of 2015/16. Based on case studies and expert interviews in the aforementioned three countries, it analyses the institutional interplay between actors in both the multi-level system and the local sphere. The authors examine the national contexts, local institutional settings and crisis-related challenges of integration management performance in the three countries, taking similarities and differences from a cross-country and inter-municipal com-parative perspective into account. Using illustrative examples from practice and deriving lessons from in-depth insights into local problem-solving, the study makes recommendations for the optimisation of integration management and more crisis-resilient administrative organisation in this policy area

Der Einfluss von ultravioletter Strahlung auf Pflanzen-Insekten Interaktionen

Plants must respond to multiple stimuli in a natural environment. Therefore they need the ability to rapidly reorganise and specifically build up appropriate metabolites to adapt to their environment. Abiotic cues, such as ambient solar radiation, influence the next trophic level directly, but also an altered plant composition triggered by these environmental cues can have an effect on the behaviour of herbivores. The aim of this study was to test effects of the important ultraviolet (UV) radiation on plants and on plant-insect interactions using multi-level investigations. The focus was on the conduction of controlled experiments with broccoli plants in highly engineered greenhouses covered with innovative materials, which only differed in their UV-B transmission. For the first time in this controlled environment the plant-mediated UV-B effects on phloem-feeding aphids were studied. Broccoli plants (Brassica oleracea L. convar. botrytis, Brassicaceae) were under filter tents either exposed to (inclusion, +UV) or not exposed to (exclusion, -UV) UV-A / UV-B radiation. In greenhouses covered with new, innovative materials transmitting high (80%), medium (23%) or low (4%) levels of ambient solar UV-B radiation, in particular the influence of UV-B radiation on broccoli was examined. Plants respond highly specific to environmental stimuli such as UV-B radiation and herbivory. UV-B radiation has a strong impact on the plants’ architecture and flavonoid contents, which can in turn influence plant-insect interactions. Phloem-feeding aphids can be negatively affected by UV-B mediated plant changes. However, a direct effect of UV radiation on the behaviour of herbivores is also evident. Mainly the number, composition and quality of herbivorous species as well as an exceeding of a certain infestation threshold determine the mode of plant changes. In conclusion, UV-B radiation has the potential to harden plants against herbivores and simultaneously increases the concentrations of valuable secondary metabolites for human nutrition in important crop species such as broccoli.In ihrer natürlichen Umgebung sind Pflanzen verschiedensten und vor allem wechselnden Umwelteinflüssen ausgesetzt, auf die sie schnell und angemessen reagieren müssen. Das Insektenverhalten der nächsten trophischen Ebene wird direkt durch abiotische Umweltfaktoren, wie zum Beispiel Sonnenstrahlung, sowie durch daraus resultierende Veränderungen in Pflanzen gesteuert. Das Ziel dieser Untersuchung war es, herauszufinden, wie sich ultraviolette (UV) Strahlung auf Pflanzen und Pflanzen-Insekten Interaktionen auswirken kann. Dies wurde auf verschiedensten Ebenen untersucht. Mit Hilfe von speziell angefertigten Gewächshäusern konnten Brokkolipflanzen unter kontrollierten UV-B Bedingungen angezogen werden. Der Einfluss von UV-B Strahlung auf Brokkoli und von UV-B induzierten Effekten in Brokkoli auf phloem-fressende Blattläuse wurde erstmals untersucht. Die Experimente wurden mit Brokkolipflanzen (Brassica oleracea L. convar. botrytis, Brassicaceae) durchgeführt, die in Folienzelten mit unterschiedlicher UV-Strahlungsdurchlässigkeit exponiert wurden. Die Eindeckungen der Folienzelte waren entweder UV-A / UV-B durchlässig (+UV) oder undurchlässig (-UV). Gewächshäuser mit innovativen Eindeckungsmaterialien, die speziell UV-B in hohen (80%), mittleren (23%) oder geringen (4%) Mengen transmittierten, wurden genutzt, um den alleinigen Effekt von UV-B Strahlung auf Pflanzen hervorzuheben. Pflanzen reagieren auf verschiedene Umweltreize wie zum Beispiel UV-B Strahlung und Herbivorie sehr zielgerichtet. UV-B Strahlung hat einen starken Einfluss auf das Pflanzenwachstum und die Flavonoidgehalte, was wiederum Pflanzen-Insekten Interaktionen artspezifisch steuern kann. Phloem-fressende Herbivoren können durch UV-B-induzierte Pflanzenveränderungen negativ beeinflusst werden. Ein direkter UV-Effekt auf das Verhalten von Herbivoren ist jedoch ebenfalls erwiesen. Sowohl die Anzahl, Zusammensetzung und Qualität von Herbivorenarten also auch das Überschreiten einer definierten Befallsschwelle bestimmen das Ausmaß der Pflanzenveränderungen. Zusammenfassend ist zu sagen, dass UV-B Strahlung Pflanzen gegenüber Fraßfeinden abhärten und gleichzeitig die Konzentration wertvoller pflanzlicher Inhaltsstoffe für die menschliche Ernährung in Feldfrüchten erhöhen kann

Development-dependent effects of UV radiation exposure on broccoli plants and interactions with herbivorous insects

Kuhlmann F, Müller C. Development-dependent effects of UV radiation exposure on broccoli plants and interactions with herbivorous insects. ENVIRONMENTAL AND EXPERIMENTAL BOTANY. 2009;66(1):61-68.The responses of plants to stress can highly depend on their developmental stage and furthermore influence biotic interactions. Effects of outdoor exposure to different ambient radiation conditions including (+UV) or excluding (-UV) solar ultraviolet radiation were investigated in broccoli plants (Brassica oleracea L. convar. botrytis) at two developmental stages. Plants either germinated directly under these different outdoor UV conditions, or were first kept for three weeks in a climate chamber under low radiation before outside exposure at +UV and -UV. Access of herbivores to the plants was possible under the outdoor conditions. Plants of both groups protected their tissue against destructive UV by increasing concentrations of phenolic compounds (flavonoids and hydroxycinnamic acids) after +UV exposure. But only plants that germinated under +UV conditions kept smaller than plants grown under -UV conditions, indicating certain costs for production of phenolics or for other potential metabolic processes specifically in young, growing plants. In contrast, growth of plants transferred at a later stage did not differ under both UV conditions. Thus, plants responded much more sensitive to the environment they experienced at first growth. Glucosinolates, the characteristic secondary compounds of Brassicaceae, as well as proteinase inhibitors, remained unaffected by UV in all plants, demonstrating independent regulation pathways for different metabolites. Plant infestation by phloem-feeding insects, Aleyrodidae and Aphididae, was more pronounced on +UV exposed plants, whereas cell content feeders, like Thripidae were more abundant on plants under the -UV condition. Choice experiments with the cabbage whitefly Aleyrodes proletella L. (Aleyrodidae), commonly found on Brassica spp., revealed that the key environmental cue navigating their behaviour seems to be the radiation composition, rather than plant quality itself. In conclusion, stress mediated changes of plant chemistry and morphology depend on the plant life cycle stage and are not necessarily mirrored in the behavioural responses of herbivorous insects. (c) 2009 Elsevier B.V. All rights reserved

Revised determination of free and complexed myrosinase activities in plant extracts

Travers-Martin N, Kuhlmann F, Müller C. Revised determination of free and complexed myrosinase activities in plant extracts. PLANT PHYSIOLOGY AND BIOCHEMISTRY. 2008;46(4):506-516.The enzyme myrosinase (thioglucoside glucohydrolase, EC 3.2.1.147, formerly EC 3.2.3.1) catalyzes the hydrolysis of glucosinolates after tissue damage in plants of the order Brassicales. The various myrosinase isoforms occur either as free soluble dimers or as insoluble complexes. We propose a reliable method for determination of both soluble and insoluble myrosinase activity concentrations in partially purified plant extracts. The procedure requires the removal of endogenous glucosinolates through ion-exchange columns previous to enzyme measurements. Myrosinase activity was assayed in continuous mode by photometric quantification of the released glucose using glucose-oxidase with peroxidase and colorimetric indicators. The measurement of the colored product at 492 nm has a favorable signal to noise ratio both in clear extract solutions (free dinners) and in turbid pellet suspensions (insoluble complexes). No interferences by ascorbic acid were found in continuous analyses. With the recommended sample preparation methods and assay conditions potential activities in damaged plant tissues can be characterized which are involved in plant defense mechanisms. (C) 2008 Elsevier Masson SAS. All rights reserved