Equicontinuous factors, proximality and Ellis semigroup for Delone sets

We discuss the application of various concepts from the theory of topological dynamical systems to Delone sets and tilings. We consider in particular, the maximal equicontinuous factor of a Delone dynamical system, the proximality relation and the enveloping semigroup of such systems.Comment: 65 page

Legitimation strategies in an emerging field: family firm succession consultancy in Germany

Finding a successor has become a severe challenge for family firms in Germany. As family firms are disproportionately concentrated in rural economies, succession has also become a considerable threat for peripheral regions and their labor markets. It therefore lies in the interest of regional stakeholders to help support family business continuity. One way to do this is by providing consulting services for family entrepreneurs, especially when searching for a family-external successor. Succession consultancy, however is still in its infancy. Applying the framework of the organizational field that centers on the concept of legitimacy, this paper examines the strategies consultants employ in order to get selected by family entrepreneurs in their succession process, as well as consultants’ strategies to match family firms with external successors. Based on expert interviews with succession consultants in the region of Upper Palatinate in Bavaria, we demonstrate the importance of geography and interpersonal linkages in establishing legitimacy in the early stages of field formation, when heterogeneous groups of actors offer their services without set rules or standards. Our content analysis sheds light on the variety of strategies based on trust, networked, and public reputation in order to gain legitimacy as consultants, depending on whether or not they can draw on existing relationships with family firms. We furthermore identify a discrepancy between these legitimation strategies and the actual ways that consultants use to match family firms with external successors. Here, regardless of their previous contact with family firms, geography plays a major role in constraining both consulting and succession: Family firms more readily accept local consultants, and the consultants also preferred to screen succession candidates through their regional networks due to the higher chances of successful succession when finding external successors from within the same region. Conceptually, our analysis contributes to institutional theory by carving out legitimacy-enhancing mechanisms in emerging organizational fields, and by demonstrating the crucial role of geography and interpersonal linkages for succession as well as field formation processes

Struktur-Eigenschafts-Beziehungen in der Leistungsfähigkeit von phosphorhaltigen Flammschutzmitteln für Polyurethan-Schäume

Polyisocyanurat (PIR)-Schaumstoffe werden aufgrund ihrer geringen Wärmeleitfähigkeit, der hohen Druckstabilität bei geringer Dichte und der geringen Wasserabsorption in vielen Bereichen eingesetzt. Zu den Anwendungsgebieten zählen Isolierungen und der Gebäudebau. In diesen Anwendungsbereichen ist eine flammhemmende Wirkung der verwendeten Materialien gefordert. PIR-Schäume an sich zählen jedoch zu den leicht entflammbaren Stoffen. Ohne den Einsatz von Flammschutzmitteln wäre somit die vielseitige Anwendung von PIR nicht möglich. In der Industrie wird bislang als „state-of-the-art“-Flammschutzmittel für PIR-Schäume das Additiv Tris(2-chloroisopropyl)phosphat (TCPP) verwendet. Nachteil des TCPPs und aller anderen halogenhaltigen Flammschutzmittel sind die beim Verbrennen freigesetzten korrosiven und toxischen Gase. Aufgrund dieses Gesundheitsaspektes, staatlicher Regulierungen und öko-Zertifizierungen geht der Trend zu halogenfreien Flammschutzmitteln. Zu vielversprechenden Alternativen zählen an dieser Stelle phosphorhaltige Verbindungen. In dieser Arbeit wurde eine Reihe von Phosphonat-basierten Additiven für PIR synthetisiert. Als Grundlage dieser Additive diente das Phosphonat Dibenzo[d,f][1,3,2]dioxa-phosphepin-6-oxid (BPPO). Durch eine Phospha-Michael-Addition des BPPOs an ungesättigte Verbindungen wurden Additive gewonnen, welche der Schaumformulierung zugesetzt werden konnten. Neben ungesättigten Verbindungen wurden auch Aldehyde mit BPPO umgesetzt, wobei dazu die Pudovik-Reaktion genutzt wurde. Hierdurch konnten BPPO-Derivate erzeugt werden, welche OH-Gruppen aufweisen. Diese können durch eine Addition an das Polyisocyanat kovalente Bindungen zum Polymer ausbilden, was ein Herausmigrieren der Additive verhindert. Durch diese beiden Reaktionsmechanismen wurden zwei Gruppen an BPPO-Derivaten synthetisiert, welche bislang noch nicht in der Literatur als Flammschutzmittel beschrieben worden sind. Durch die Addition verschiedener organischer Verbindungen wurde die chemische Struktur dieser BPPO-Derivate systematisch variiert. Durch diese Variation und anschließende Untersuchungen konnten Struktur-Eigenschafts-Beziehungen aufgestellt werden. Nach der erfolgreichen Synthese wurden die P-haltigen Verbindungen in PIR-Schäumen verwendet. Parallel dazu wurden Benchmark-Schäume hergestellt, die Flammschutzmittel aus der Literatur und der Industrie enthielten. Die physikalischen Eigenschaften der so hergestellten Schäume wurden anschließend untersucht. Ebenso wurde das thermische Abbauverhalten sowie das Brandverhalten analysiert. Die Ergebnisse wurden mit denen der Benchmark-Schäume verglichen und liefern einen wesentlichen Beitrag zum Verständnis der grundlegenden Struktur-Eigenschafts-Beziehungen im Flammschutz von Polyurethanen. Wie aus der Literatur bereits bekannt, ist die Wirkungsweise phosphorhaltiger Flammschutzmittel abhängig von der Oxidationszahl des Phosphoratoms. Bei höheren Oxidationszahlen findet die flammhemmende Wirkung in der Festphase und bei niedrigeren Oxidationszahlen in der Gasphase statt. Dieser Trend konnte durch den vergleichenden Einsatz von chemisch ähnlichen Phosphinaten, Phosphonaten und Phosphaten bestätigt werden. Ein weiterer wichtiger Einflussfaktor ist die Bindung des Additivs im Schaum. Des Weiteren konnte in dieser Arbeit gezeigt werden, dass Verbindungen mit aromatischen Gruppen sich positiv auf das Brandverhalten auswirken. Diese Ergebnisse tragen wesentlich zum Verständnis der grundlegenden Struktur-Eigenschafts-Beziehungen beim Flammschutz von Polyurethanen bei. Dies wiederum ermöglicht Vorhersagen über das Verhalten von phosphorhaltigen Additiven im Schaum und deren Auswirkungen auf den Flammschutz. Ebenso ist es möglich, mit den gewonnenen Erkenntnissen bestehende Additive durch die Anpassung ihrer chemischen Struktur zu optimieren oder für ein spezielles Einsatzgebiet neu zu entwickeln. Mit TA-BPPO als Additiv konnten zudem bessere Flammschutzeigenschaften erzielt werden als mit dem analogen Derivat des DOPO. Abschließend lässt sich sagen, dass mit BPPO und seinen Derivaten eine wirksame Alternative zu dem bislang verwendeten Triphenylphosphat gefunden wurde. Die erhaltenen Resultate legen eine Anwendung in der Industrie nahe.Polyisocyanurate (PIR) foams are used in many areas due to their low thermal conductivity, high pressure stability at low density and low water absorption. Applications include insulation, building construction and the automotive industry. In these applications, the materials used, need to have a flame retardant effect. PIR foams themselves are highly flammable materials. Without the use of flame retardants, the versatile application of PIR would not be possible. In industry the additive tris(2-chloroisopropyl)phosphate (TCPP) is currently used as a ”state-of-the-art“flame retardant for PIR foams. The disadvantage of TCPP and all other halogen-containing flame retardants are the corrosive and toxic gases released during combustion. Due to this health aspect, governmental regulations and eco-certifications the trend leads towards halogen-free flame retardants . Promising alternatives at this point include phosphorous-containing compounds. In this work a number of phosphonate-based additives for PIR were synthesized. The phosphonate dibenzo[d,f][1,3,2]dioxa-phosphepine-6-oxide (BPPO) served as the basis for these additives. Additives were obtained by Phospha-Michael addition of BPPO to unsaturated compounds, which could be added to the foam formulation. Besides unsaturated compounds, aldehydes were also reacted with BPPO using the Pudovik reaction. By this means, BPPO derivatives with OH groups could be produced. These can form covalent bonds to the polymer by addition to the polyisocyanate, which prevents the additives from migrating out. By these two reaction mechanisms two groups of BPPO derivatives were synthesized, which have not yet been described as flame retardants in the literature. By adding different organic compounds, the chemical structure of these BPPO derivatives was systematically varied. By this variation and subsequent investigations structure-property relationships could be established. After successful synthesis, the P-containing compounds were used in PIR foams. In parallel, benchmark foams containing flame retardants from literature and industry were produced. The physical properties of the foams produced in this way were then investigated. The thermal degradation behaviour as well as the fire behaviour was also analysed. The results were compared with those of the benchmark foams and provide a significant contribution to the understanding of the basic structure-property relationships in the flame retardancy of polyurethanes. As already known from the literature, the mode of action of phosphorous-containing flame retardants depends on the oxidation number of the phosphorus atom. At higher oxidation numbers the flame retardant effect takes place in the solid phase and at lower oxidation numbers in the gas phase. This trend was confirmed by the comparative use of chemically similar phosphinates, phosphonates and phosphates. Another important influencing factor is the binding of the additive in the foam. Furthermore it could be shown in this work that compounds with aromatic groups have a positive effect on the fire behavior. These results contribute significantly to the understanding of the basic structure-property relationships in flame retardancy of polyurethanes. This in turn allows predictions to be made about the behavior of phosphorus-containing additives in the foam and their effects on flame retardancy. It is also possible to optimize existing additives by adapting their chemical structure, or to develop new additives for a specific application. With TA-BPPO as an additive, it was also possible to achieve better flame retardant properties than with the analogue derivative of DOPO.In conclusion, BPPO and its derivatives are an effective alternative to the triphenyl phosphateused so far. The results obtained suggest an application in industry

Lifetimes of bb-hadrons and mixing of neutral BB-mesons: theoretical and experimental status

In this article, we review the current status of $B$-mixing and $b$-hadron lifetimes both from experimental and theoretical points of view. Furthermore, we discuss the phenomenological potential of these observables for deepening our understanding of quantum chromodynamics (QCD) and for indirect searches for effects beyond the Standard Model (SM). In addition, we present new updated SM predictions for the mixing observables $\Delta M_{d,s}$, $\Delta \Gamma_{d,s}$ and $a_{fs}^{d,s}$. We conclude with an outlook on future prospects for theoretical and experimental improvements.Comment: Invited review for EPJST. 26 pages, 26 figures, 6 tables, 306 reference

Lässt sich das Dasein Gottes aus der Natur beweisen? : Vortrag

Digiteeritud Euroopa Regionaalarengu Fondi rahastusel, projekti "Eesti teadus- ja õppekirjandus" (2014-2020.12.03.21-0848) raames.https://www.ester.ee/record=b4005724*es

Basic Human Body Dimensions Relate to Alcohol Dependence and Predict Hospital Readmission

Alcohol dependence is a severe mental illness and there is a need for more effective preventive and therapeutic strategies. Translational research suggests that intrauterine sex hormone exposure modulates the risk and course of alcohol dependence during adulthood. During development, sex hormones permanently shape sexually dimorphic body dimensions. Thus, these dimensions may provide insight into sex hormone organization. Here, we compared body measurements (absolute, relative to, and residualized on height) between 200 alcohol-dependent in-patients and 240 age-matched healthy control subjects and investigated how these measurements associate with the patients’ prospective 12- and 24-month outcome. The results show that alcohol dependence is related to lower absolute, relative, and residualized body measurements for height and weight, head circumference, bitragion head arc, lip-chin distance, hip, thigh, and calf circumference, and foot length and breadth. In male alcohol-dependent in-patients, higher risk, shorter latency, and more alcohol-related readmissions were predicted by higher absolute, relative, and residualized thigh and calf circumferences. The second-to-fourth finger length ratio, a putative proxy for prenatal sex hormone organization, was not convincingly correlated with the body dimensions, suggesting that the results represent pubertal (or later) effects. The study’s findings have implications for further research. The body measurements’ high accessibility may facilitate the future transition into clinical settings

Stochastic Market Games

Some of the most relevant future applications of multi-agent systems like autonomous driving or factories as a service display mixed-motive scenarios, where agents might have conflicting goals. In these settings agents are likely to learn undesirable outcomes in terms of cooperation under independent learning, such as overly greedy behavior. Motivated from real world societies, in this work we propose to utilize market forces to provide incentives for agents to become cooperative. As demonstrated in an iterated version of the Prisoner's Dilemma, the proposed market formulation can change the dynamics of the game to consistently learn cooperative policies. Further we evaluate our approach in spatially and temporally extended settings for varying numbers of agents. We empirically find that the presence of markets can improve both the overall result and agent individual returns via their trading activities.Comment: IJCAI-2

Recovery of scandium from acidic waste solutions by means of polymer inclusion membranes

Scandium is a raw material with properties that promise considerable potential for application in alloys to enable aviation fuel savings and as dopants for use in sustainable energy production using solid oxide fuel cells. Despite these attractive properties, scandium is rarely used due to its scarcity and unreliable supply. Therefore, new strategies for scandium recovery are of economic priority. In this study, polymer inclusion membranes (PIMs) consisting of PVDF-HFP, 2-NPOE and DEHPA, were optimised for selective scandium separation from real TiO2 production waste. With the optimised system, >60% of the scandium was recovered with high selectivity, resulting in scandium mole fraction at more than two orders of magnitude higher in the receiving phase than in the original waste. This suggests PIMs may be an effective way to recover scandium from bulk waste, thus easing the scarcity and insecurity that currently limit its bulk application