Aims. H.E.S.S. observes an increasing number of large extended sources. A new technique based on the structure of the sky map is developed to account for these additional structures by comparing them ...with the common point source analysis. Methods. Minkowski functionals are powerful measures from integral geometry. They can be used to quantify the structure of the counts map, which is then compared with the expected structure of a pure Poisson background. Gamma-ray sources lead to significant deviations from the expected background structure. The standard likelihood ratio method is exclusively based on the number of excess counts and discards all further structure information of large extended sources. The morphometric data analysis incorporates this additional geometric information in an unbiased analysis, i.e., without the need of any prior knowledge about the source. Results. We have successfully applied our method to data of the H.E.S.S. experiment. The morphometric analysis presented here is dedicated to detecting faint extended sources.
Ubiquitin-mediated proteolysis is an integral part of diverse cellular functions, and of the three enzymes involved in linking ubiquitin to protein targets, the E3 ubiquitin ligases are of particular ...interest as they confer substrate specificity during this process. The E3 ubiquitin ligases can be categorized based on mechanism of action and on the presence of specific domains such as RING, HECT, F-box, and U-box. In plants, the U-box family has undergone a large gene expansion that may be attributable to biological processes unique to the plant life cycle. For example, there are 64 predicted plant U-box (PUB) proteins in Arabidopsis, and the biological roles of many of these have yet to be determined. Research on PUB genes from several different plants has started to elucidate a range of functions for this family, from self-incompatibility and hormone responses to defence and abiotic stress responses. Expression profiling has also been used as a starting point to elucidate PUB function, and has uncovered a strong connection of PUB genes to various stress responses. Finally, some PUB proteins have been linked to receptor kinases as upstream activators, and downstream target substrates are also starting to emerge. The mechanisms of action range from the observation of mono-ubiquitination during non-proteolytic signalling to directed regulation of proteasomal components during stress responses, and cell death appears to be a theme underlying many PUB functions.
A new metallocene-based polymerization mechanism is elucidated in which a zirconium hydride center inserts α-methylstyrene at the start of a polymer chain. The hydride is then regenerated by ...hydrogenation to release a polyolefin containing a single terminal α-methylstyrenyl group. Through the use of the difunctional monomer 1,3-diisopropenylbenzene, this catalytic hydride insertion polymerization is applied to the production of linear polyethylene and ethylene–hexene copolymers containing an isopropenylbenzene end group. Conducting simple radical polymerizations in the presence of this new type of macromonomer leads to diblock copolymers containing a polyolefin attached to an acrylate, methacrylate, vinyl ester, or styrenic segments. The new materials are readily available and exhibit interfacial phenomena, including the mediation of the mixing of immiscible polymer blends.
The High Energy Stereoscopic System (H.E.S.S.) is a system of Imaging Atmospheric Cherenkov Telescopes (IACTs) located in the Khomas Highland in Namibia. It measures cosmic gamma rays of very high ...energies (VHE; >100GeV) using the Earth’s atmosphere as a calorimeter. The H.E.S.S. Array entered Phase II in September 2012 with the inauguration of a fifth telescope that is larger and more complex than the other four. This paper will give an overview of the current H.E.S.S. central data acquisition (DAQ) system with particular emphasis on the upgrades made to integrate the fifth telescope into the array. At first, the various requirements for the central DAQ are discussed then the general design principles employed to fulfil these requirements are described. Finally, the performance, stability and reliability of the H.E.S.S. central DAQ are presented. One of the major accomplishments is that less than 0.8% of observation time has been lost due to central DAQ problems since 2009.
In the Brassicaceae, the acceptance of compatible pollen and the rejection of self-incompatible pollen by the pistil involves complex molecular communication systems between the pollen grain and the ...female reproductive structures. Preference towards species related-pollen combined with self-recognition systems, function to select the most desirable pollen; and thus, increase the plant's chances for the maximum number of successful fertilizations and vigorous offspring. The Brassicaceae is an ideal group for studying pollen–pistil interactions as this family includes a diverse group of agriculturally relevant crops as well as several excellent model organisms for studying both compatible and self-incompatible pollinations. This review will describe the cellular systems in the pistil that guide the post-pollination events, from pollen capture on the stigmatic papillae to pollen tube guidance to the ovule, with the final release of the sperm cells to effect fertilization. The interplay of other recognition systems, such as the self-incompatibility response and interspecific interactions, on regulating post-pollination events and selecting for compatible pollen–pistil interactions will also be explored.
Despiking Acoustic Doppler Velocimeter Data Goring, Derek G; Nikora, Vladimir I
Journal of hydraulic engineering (New York, N.Y.),
01/2002, Letnik:
128, Številka:
1
Journal Article
Recenzirano
A new method for detecting spikes in acoustic Doppler velocimeter data sequences is suggested. The method combines three concepts: (1) that differentiation enhances the high frequency portion of a ...signal, (2) that the expected maximum of a random series is given by the Universal threshold, and (3) that good data cluster in a dense cloud in phase space or Poincaré maps. These concepts are used to construct an ellipsoid in three-dimensional phase space, then points lying outside the ellipsoid are designated as spikes. The new method is shown to have superior performance to various other methods and it has the added advantage that it requires no parameters. Several methods for replacing sequences of spurious data are presented. A polynomial fitted to good data on either side of the spike event, then interpolated across the event, is preferred by the authors.
Screening of a yeast two-hybrid library for proteins that interact with the kinase domain of an S-locus receptor kinase (SRK) resulted in the isolation of a plant protein called ARC1 (Arm Repeat ...Containing). This interaction was mediated by the C-terminal region of ARC1 in which five arm repeat units were identified. Using the yeast two-hybrid system and in vitro binding assays, ARC was found to interact specifically with the kinase domains from SRK-910 and SRK-A14 but failed to interact with kinase domains from two different Arabidopsis receptor-like kinases. In addition, treatment with a protein phosphatase or the use of a kinase-inactive mutant reduced or abolished the binding of ARC1 to the SRK-910 kinase domain, indicating that the interaction was phosphorylation dependent. Lastly, RNA blot analysis revealed that the expression of ARC1 is restricted to the stigma, the site of the self-incompatibility response
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