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Various particle filters have been proposed over the last couple of decades with the common feature that the update step is governed by a type of control law. This feature makes them an attractive alternative to traditional sequential Monte Carlo which scales poorly with the state dimension due to weight degeneracy. This article proposes a unifying framework that allows us to systematically derive the McKean-Vlasov representations of these filters for the discrete time and continuous time observation case, taking inspiration from the smooth approximation of the data considered in [D. Crisan and J. Xiong, Stochastics, 82 (2010), pp. 53-68; J. M. Clark and D. Crisan, Probab. Theory Related Fields, 133 (2005), pp. 43-56]. We consider three filters that have been proposed in the literature and use this framework to derive Ito representations of their limiting forms as the approximation parameter delta -> 0. All filters require the solution of a Poisson equation defined on R-d, for which existence and uniqueness of solutions can be a nontrivial issue. We additionally establish conditions on the signal-observation system that ensures well-posedness of the weighted Poisson equation arising in one of the filters.
A series of biomass-derived levoglucosenyl alkyl ethers (alkyl = methyl, ethyl, n-propyl, isopropyl, and n-butyl) were synthesized and polymerized by ring-opening olefin metathesis polymerization using the Grubbs catalyst C793 at room temperature. Polymerizations were successfully performed in conventional solvents such as 1,4-dioxane and dichloromethane as well as in polar aprotic "green" solvents such as 2-methyltetrahydrofuran, dihydrolevoglucosenone (Cyrene), and ethyl acetate. The prepared polyacetals with degrees of polymerization of similar to 100 exhibit Schulz-Flory-type molar mass distributions and are thermoplastic materials with rather low glass transition temperatures in the range of 43-0 degrees C depending on the length of the alkyl substituent. Kinetic studies revealed that the polymerization proceeded rapidly to a steady state with a certain minimum monomer concentration threshold. When the steady state was reached, just about half of the [Ru] catalyst had been effective to initiate the polymerization, indicating that the initiation step was a slow process. The remaining catalyst was still active and did no longer react with monomers but with in-chain double bonds, cutting the formed polymer chains into shorter fragments. In the long term, all catalyst was consumed and propagating [Ru] chain ends were deactivated by the elimination of [Ru] from the chain ends to form inactive chains with terminal aldehyde groups.
From employee to expert
(2021)
In the context of the collaborative project Ageing-appropriate, process-oriented and interactive further training in SME (API-KMU), innovative solutions for the challenges of demographic change and digitalisation are being developed for SMEs. To this end, an approach to age-appropriate training will be designed with the help of AR technology. In times of the corona pandemic, a special research design is necessary for the initial survey of the current state in the companies, which will be systematically elaborated in this paper. The results of the previous methodological considerations illustrate the necessity of a mix of methods to generate a deeper insight into the work processes. Video-based retrospective interviews seem to be a suitable instrument to adequately capture the employees' interpretative perspectives on their work activities. In conclusion, the paper identifies specific challenges, such as creating acceptance among employees, open questions, e.g., how a transfer or generalization of the results can succeed, and hypotheses that will have to be tested in the further course of the research process.
In recent years, all over the globe we have seen intensifying economic exploitation, political disenfranchisement, social marginalization and cultural repression in all kinds of political regimes, from liberal democratic to authoritarian and dictatorial. Although the strategies vary with regard to regime and context, in all of them we observe that while a growing number of social groups are speaking out and rising against them, a presumably much higher number of groups do not. In this article, I argue that all these processes can be conceived as aspects of ongoing closure struggles in social life. However, in order to understand why some social groups are able to fight against closure strategies while others are not, closure theory in its current state of elaboration is not of any help. While it operates with the term solidarization, it does not offer any explanation of how such acting in solidarity may become possible in closure struggles. The article is a mainly theoretical contribution of how to solve this problem.
The recent debate on administrative bodies in international organizations has brought forward multiple theoretical perspectives, analytical frameworks, and methodological approaches. Despite these efforts to advance knowledge on these actors, the research program on international public administrations (IPAs) has missed out on two important opportunities: reflection on scholarship in international relations (IR) and public administration and synergies between these disciplinary perspectives. Against this backdrop, the essay is a discussion of the literature on IPAs in IR and public administration. We found influence, authority, and autonomy of international bureaucracies have been widely addressed and helped to better understand the agency of such non-state actors in global policy-making. Less attention has been given to the crucial macro-level context of politics for administrative bodies, despite the importance in IR and public administration scholarship. We propose a focus on agency and politics as future avenues for a comprehensive, joint research agenda for international bureaucracies.
Nach den beiden großen Forschungsreisen konzentrierte Ehrenberg seine Arbeit in Berlin auf die systematische Beschreibung von Kleinstlebewesen, die sogenannten Infusorien. 1838 erschien eines seiner Hauptwerke, Die Infusionsthierchen als vollkommene Organismen. Ein Blick in das tiefere organische Leben der Natur. Ehrenberg untersuchte tausende Proben aus aller Welt und wies Infusorien auf dem Grund der Weltmeere, in atmosphärischem Staub und in Hochgebirgen nach. Ausgehend von diesen Befunden beschäftigte er sich mit dem Anteil einzelliger kieselschaliger Mikroorganismen an der Bildung von Erden und geologischen Formationen. 1854 legte er die Mikrogeologie vor: In 41 Bildtafeln gab er weltweite „geographische Uebersichten über das kleine jetzige erdbildende Leben“. Christian Gottfried Ehrenberg gilt als Mitbegründer der Boden-Mikrobiologie und Mikropaläontologie sowie als Pionier der Kieselalgenforschung und Protozoologie.
„Eine der größten Freuden meines Lebens würde sein, einmal 5 – 6 Monathe mit Ihnen, an Ihrer Seite, unter Ihrer Belehrung reisen zu können. Süßwassermuscheln, Fische, Bergpflanzen Rußlands sind wenig bekannt.“ Mit diesen Worten lud Alexander von Humboldt seinen Akademiekollegen Ehrenberg zur Teilnahme an der russisch-sibirischen Reise ein, die der preußische Kammerherr auf Einladung des Kaisers Nikolaj I. unternahm. Knapp drei Jahre nach der Rückkehr von der arabisch-afrikanischen Forschungsreise brach Ehrenberg also erneut auf: Am 12. April 1829 traten Humboldt, Ehrenberg und der Mineraloge Gustav Rose ihre Reise in Berlin an. Diese führte sie in knapp neun Monaten und über 19 000 Kilometer in den Ural und durch Westsibirien bis zur russisch-chinesischen Grenzstation Baty. Während Humboldt und Rose die Hüttenbezirke im Ural und Altai inspizierten, legte Ehrenberg botanische und zoologische Sammlungen an.
Heinrich Menu von Minutoli unternahm 1820 eine Reise nach Nordafrika zur Erforschung ägyptischer und griechischer Altertümer. Die Preußische Akademie der Wissenschaften bestimmte die jungen Naturforscher Christian Gottfried Ehrenberg und Wilhelm Hemprich als weitere Teilnehmer.
Während Minutoli bereits ein Jahr nach Beginn der Expedition 1821 nach Europa zurückkehrte, setzten Ehrenberg und Hemprich ihre Forschungen fort. Von Alexandria aus unternahmen sie, zum Teil getrennt, Exkursionen in die libysche Wüste, auf die Sinaihalbinsel, zum Roten Meer, in das Libanongebirge sowie bis in den Sudan und nach Eritrea, wo Hemprich 1825 dem Malariafieber erlag.
Wie von der Akademie der Wissenschaften beauftragt, sammelten Ehrenberg und Hemprich insgesamt 34 000 Tiere, 46 000 Pflanzen und 300 Mineralien. Diese trafen im Laufe der Jahre, verpackt in insgesamt 114 Kisten, in Berlin ein. Die Akademie stellte Mittel für die Auswertung der Sammlungen zur Verfügung. Ehrenbergs Reisebericht blieb aber ebenso Fragment wie das großangelegte Tafelwerk Symbolae physicae.