952 research outputs found
Uniformly bounded components of normality
Suppose that is a transcendental entire function and that the Fatou
set . Set and
where the supremum is taken over all components of
. If or , then we say is strongly
uniformly bounded or uniformly bounded respectively. In this article, we will
show that, under some conditions, is (strongly) uniformly bounded.Comment: 17 pages, a revised version, to appear in Mathematical Proceedings
Cambridge Philosophical Societ
Geminale Bis(sulfoximin)e als Liganden für die Seltenerdmetall-katalysierte Enantioselektive Intramolekulare Hydroaminierung von Aminoolefinen
Ausgehend von dem freien geminalen Bis(sulfoximin) Bi(SON-H) gelang die Synthese einer Reihe von N-silylierten, N arylierten und N-alkylierten Derivaten. Stellvertretend für diese neue Ligandenklasse erfolgte die Untersuchung des Koordinationsverhaltens von Bi(SON-TBS) auf verschiedenen Wegen: Die Synthese des Kalium-Komplexes zeigte eine quantitative Deprotonierung des Bis(sulfoximin)s an der Methylenbrücke zwischen den Schwefelatomen. Über eine Kristallstrukturanalyse des Kalium-Komplexes konnte zudem erstmalig die Koordination eines Metalls über die Sauerstoffatome eines geminalen Bis(sulfoximin)s nachgewiesen werden. Die Charakterisierung der mit Y[N(SiMe3)2]3 gebildeten Yttrium-Komplexe von Bi(SON-TBS) erfolgte mittels 89Y-NMR-Spektroskopie, DOSY-NMR, Job Plot und DFT-Rechnungen. Dabei zeigte sich unabhängig von der Zusammensetzung eine Präferenz zur Bildung eines Komplexes bestehend aus drei Bis(sulfoximin)en und einem Yttriumatom.
Die neuen Bis(sulfoximin)e wurden als Liganden für die Seltenerdmetall-katalysierte enantioselektive intramolekulare Hydroaminierung von Aminoolefinen mit den Metallen Yttrium, Lutetium, Scandium und Lanthan verwendet. Bei quantitativer Umsetzung wurden bis zu 65 % Enantiomerenüberschuss erreicht
High-resolution satellite-based cloud detection for the analysis of land surface effects on boundary layer clouds
The observation of boundary layer clouds with high-resolution satellite data can provide comprehensive insights into spatiotemporal patterns of land-surface-driven modification of cloud occurrence, such as the diurnal variation of the occurrence of fog holes and cloud enhancements attributed to the impact of the urban heat island. High-resolution satellite-based cloud-masking approaches are often based on locally optimised thresholds that can be affected by the local surface reflectance, and they therefore introduce spatial biases in the detected cloud cover. In this study, geostationary satellite observations are used to develop and validate two high-resolution cloud-masking approaches for the region of Paris to show and improve applicability for analyses of urban effects on clouds. Firstly, the Local Empirical Cloud Detection Approach (LECDA) uses an optimised threshold to separate the distribution of visible reflectances into cloudy and clear sky for each individual pixel accounting for its locally specific brightness. Secondly, the Regional Empirical Cloud Detection Approach (RECDA) uses visible reflectance thresholds that are independent of surface reflection at the observed location. Validation against in-situ cloud fractions reveals that both approaches perform similarly, with a probability of detection (POD) of 0.77 and 0.69 for LECDA and RECDA, respectively. Results show that with the application of RECDA a decrease of cloud cover during typical fog or low-stratus conditions over the urban area of Paris for the month of November is likely a result of urban effects on cloud dissipation. While LECDA is representative for the widespread usage of locally optimised approaches, comparison against RECDA reveals that the cloud masks obtained from LECDA result in regional biases of ±5 % that are most likely caused by the differences in surface reflectance in and around the urban areas of Paris. This makes the regional approach, RECDA, a more appropriate choice for the high-resolution satellite-based analysis of cloud cover modifications over different surface types and the interpretation of locally induced cloud processes. Further, this approach is potentially transferable to other regions and temporal scales for analysing long-term natural and anthropogenic impacts of land cover changes on clouds
Indoleamine 2,3-Dioxygenase in Human Hematopoietic Stem Cell Transplantation
In recent years tryptophan metabolism and its rate limiting enzyme indoleamine 2,3-dioxygenase (IDO) have attracted increasing attention for their potential to modulate immune responses including the regulation of transplantation tolerance. The focus of this review is to discuss some features of IDO activity which particularly relate to hematopoietic stem cell transplantation (HSCT). HSCT invariably involves the establishment of some degree of a donor-derived immune system in the recipient. Thus, the outstanding feature of tolerance in HSCT is that in this type of transplantation it is not rejection, which causes the most severe problems to HSCT recipients, but the reverse, graft-versus-host (GvH) directed immune responses. We will discuss the peculiar role of IDO activity and accelerated tryptophan metabolism at the interface between immune activation and immune suppression and delineate from theoretical and experimental evidence the potential significance of IDO in mediating tolerance in HSCT. Finally, we will examine therapeutic options for exploitation of IDO activity in the generation of allo-antigen-specific tolerance, i.e. avoiding allo-reactivity while maintaining immunocompetence, in HSCT
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