60 research outputs found

    Quenching of the radio jet during the X-ray high state of GX 339-4

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    We have observed the black hole candidate X-ray binary GX 339-4 at radio wavelengths before, during and after the 1998 high/soft X-ray state transition. We find that the radio emission from the system is strongly correlated with the hard X-ray emission and is reduced by a factor > 25 during the high/soft state compared to the more usual low/hard state. At the points of state transition we note brief periods of unusually optically-thin radio emission which may correspond to discrete ejection events. We propose that in the low/hard state black hole X-ray binaries produce a quasi-continuous outflow, in the high/soft state this outflow is suppressed, and that state transitions often result in one or more discrete ejection events. Future models for low/hard states, such as ADAF/ADIOS solutions, need to take into account strong outflow of relativistic electrons from the system. We propose that the inferred Comptonising corona and the base of the jet-like outflow are the same thing, based upon the strong correlation between radio and hard X-ray emission in GX 339-4 and other X-ray binaries, and the similarity in inferred location and composition of these two components.Comment: Accepted for publication in ApJ Letter

    Novel selective butyrylcholinesterase inhibitors incorporating antioxidant functionalities as potential bimodal therapeutics for Alzheimer’s Disease

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    Isosorbide-2-carbamates-5-aryl esters are highly potent and very selective butyrylcholinesterase inhibitors. The objective of the present work was to address the hypothesis that the isosorbide-aryl-5-ester group could be replaced with an antioxidant functionality while maintaining inhibitor effects and selectivity. We successfully incorporated ferulic acid or lipoic acid groups producing potent selective inhibitors of butyrylcholinesterase (BuChE). The hybrid compounds were non-toxic to the murine hippocampal cell line HT-22 and lipoate esters were neuroprotective at 10 and 25 mu M when the cells were challenged with glutamate (5 mM) in a similar manner to the positive control quercetin. The benzyl carbamate 7a was a potent inhibitor of BuChE (IC50 150 nM) and it was effective in reducing glutamate toxicity to neuronal cells at >5 mu M. Representative compounds exhibited an antioxidant effect in the oxygen radical absorbance capacity assay as the lipoate 7d was not active, whereas the ferulate 8a showed a weak, but significant, activity with 0.635 +/- 0.020 Trolox Equivalent

    Guest Artist Recital: Matthew Muneses Quintet

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    Kemp Recital HallSeptember 24, 2014Wednesday Evening8:00 p.m

    Model Based Analysis and Test Generation for Flight Software

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    We describe a framework for model-based analysis and test case generation in the context of a heterogeneous model-based development paradigm that uses and combines Math- Works and UML 2.0 models and the associated code generation tools. This paradigm poses novel challenges to analysis and test case generation that, to the best of our knowledge, have not been addressed before. The framework is based on a common intermediate representation for different modeling formalisms and leverages and extends model checking and symbolic execution tools for model analysis and test case generation, respectively. We discuss the application of our framework to software models for a NASA flight mission

    Prospectus, January 20, 1975

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    STUDENTS RESPOND TO BOYCOTT; CU Mass Transit Increases Service; Few Support Canteen, Hate Food And Prices; A Separate Reality?; Dental Hygiene Gives Students Free Care; Trustees Approve Funding For New (Yellow Bricj?) Road; Amateur Radio Class To Begin; String Club To Present Music Festival; Sangamon State Rep. Here Feb. 4; Handicapped Left Out In Parking Lot Cold; Walker Blasts Fed Agencies, Refuses State-Level Tax Cut; \u27Sorry, Wrong Number\u27 Is PC Players\u27 Hit; Mighty Joe Young Sings Blues With Style; Right To Life To Meet; \u27Front Page\u27 A Flat Disappointing Comedy; what happens after boycott?; The Kaleidoscope; letters; PSA President Answers Day Care Questions; Monroe Doctrine Plays Bluegrass at PC Friday; New Student Privacy Law In Effect; The People\u27s Choice; Lit One: The Obscure Poet, Laying play dreaming..., Li Po..., Snow on the high Mountains..., Survival, Ode to you, O School!; Milhouse & Outhouse; Christmas Reprise; Classified Ads; Jack Ruby: Cubans And Strippers; File Petition For Graduation; Cobras Meet Top-Ranked Lakeland Tonight; Oliver Nets 40 Points As Cagers Rebound To Dump Springfield; Parkland No. 2 In Basketball; New Fencing Club Strives To Gain Members, Recognition; Women Cobras Open Season; Intramural Basketball; Parkland Events; Bouncing Bob\u27s Basketball Bonanzahttps://spark.parkland.edu/prospectus_1975/1018/thumbnail.jp

    Arguments Against a Configural Processing Account of Familiar Face Recognition

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    Face recognition is a remarkable human ability, which underlies a great deal of people's social behavior. Individuals can recognize family members, friends, and acquaintances over a very large range of conditions, and yet the processes by which they do this remain poorly understood, despite decades of research. Although a detailed understanding remains elusive, face recognition is widely thought to rely on configural processing, specifically an analysis of spatial relations between facial features (so-called second-order configurations). In this article, we challenge this traditional view, raising four problems: (1) configural theories are underspecified; (2) large configural changes leave recognition unharmed; (3) recognition is harmed by nonconfigural changes; and (4) in separate analyses of face shape and face texture, identification tends to be dominated by texture. We review evidence from a variety of sources and suggest that failure to acknowledge the impact of familiarity on facial representations may have led to an overgeneralization of the configural account. We argue instead that second-order configural information is remarkably unimportant for familiar face recognition

    Can forest management based on natural disturbances maintain ecological resilience?

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    Given the increasingly global stresses on forests, many ecologists argue that managers must maintain ecological resilience: the capacity of ecosystems to absorb disturbances without undergoing fundamental change. In this review we ask: Can the emerging paradigm of natural-disturbance-based management (NDBM) maintain ecological resilience in managed forests? Applying resilience theory requires careful articulation of the ecosystem state under consideration, the disturbances and stresses that affect the persistence of possible alternative states, and the spatial and temporal scales of management relevance. Implementing NDBM while maintaining resilience means recognizing that (i) biodiversity is important for long-term ecosystem persistence, (ii) natural disturbances play a critical role as a generator of structural and compositional heterogeneity at multiple scales, and (iii) traditional management tends to produce forests more homogeneous than those disturbed naturally and increases the likelihood of unexpected catastrophic change by constraining variation of key environmental processes. NDBM may maintain resilience if silvicultural strategies retain the structures and processes that perpetuate desired states while reducing those that enhance resilience of undesirable states. Such strategies require an understanding of harvesting impacts on slow ecosystem processes, such as seed-bank or nutrient dynamics, which in the long term can lead to ecological surprises by altering the forest's capacity to reorganize after disturbance
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