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In mathematics and theoretical physics, quantum groups are certain non-commutative, non-cocommutative Hopf algebras, which first appeared in the theory of quantum integrable models and later they were formalized by Drinfeld and Jimbo. In this paper we present a classification scheme for quantum groups, whose classical limit is a polynomial Lie algebra. As a consequence we obtain deformed XXX and XXZ Hamiltonians.

AbstractExisting work on the flow–performance relation in mutual funds focuses on the average U.S. investor, obscuring the contributions of different clienteles. We analyze UK data on monthly fund sales and purchases made via seven distinct distribution channels. We show that there exist marked differences in the reaction to fund performance between different types of retail and institutional investors. These differences can be understood by considering the incentives of parties involved in each channel. Our analysis indicates that the well‐documented aggregate net flow–performance convexity in mutual funds is driven by the extreme reaction of retail inflows to favorable performance, particularly from independently advised investors.

AbstractExisting work on mutual fund performance persistence obtains diverse results, depending on the group of funds studied. We examine whether performance persistence within a peer group of competing mutual funds depends on the group's composition. The U.K. mutual fund industry is ideal for such an examination because funds compete within strictly defined sectors. We consider several attributes related to the intensity of competition within a sector and use them to explain sector‐level persistence. We find robust evidence that persistence is higher in sectors where concentration of assets under management is higher.

ZusammenfassungDer Artikel beschreibt eine Patientin mit Pyoderma gangraenosum nach Kaiserschnitt. Diese Diagnose macht differenzialdiagnostische Überlegungen besonders notwendig auch zu akuten Hautinfektionen. Es wurde daher eine Literaturübersicht zum Pyoderma gangraenosum mithilfe von Suchmaschinen RINZ (Russischer wissenschaftlicher Zitierungsindex), PubMed, Scholar und Medline erstellt. Das Pyoderma gangraenosum ist eine extrem seltene Krankheit und die Diagnose stellt eine Ausschlussdiagnose dar. Bei ausgedehnter Wundoberfläche, die auf Antibiotika und chirurgische Behandlung nicht anspricht, ist eine Behandlung mit Glukokortikoiden und Immunsuppressiva notwendig. In unserem Fall hat sich das Pyoderma gangraenosum als interdisziplinäres Problem dargestellt, das eine gemeinsame Patientenführung von chirurgisch tätigen Kollegen und Dermatologen fordert.