216 research outputs found

    CMOS VHF transconductance-C lowpass filter

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    Giga view parallel image server performance analysis

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    Professionals in various fields such as medical imaging, biology and civil engineering require rapid access to huge amounts of uncompressed pixmap image data. Multi-media interfaces further increase the need for large image databases. In order to fulfill these requirements, the GigaView parallel image server architecture relies on arrays of intelligent disk nodes, each disk node being composed of one processor and one disk. This contribution analyzes through simulation and experimentation the behavior of the GigaView under single and multiple requests, and compares it to the behavior of RAID servers. It evaluates image visualization window access times under various parameters such as load factors and the number of cooperating disk nodes. Under single request, the GigaView image server can be modeled as a single high-throughput low-latency secondary storage device. Under multiple requests, the notions of utilization and maximum sustainable throughput define accurately the behavior of the GigaView

    Linear CMOS transconductance element for VHF filters

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    Completing the triad: Synthesis and full characterization of homoleptic and heteroleptic carbonyl and nitrosyl complexes of the group VI metals

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    Oxidation of M(CO)6_{6} (M = Cr, Mo, W) with the synergistic oxidative system Ag[WCA]/0.5 I2_{2} yields the fully characterized metalloradical salts [M(CO)6_{6}]+˙[WCA]− (weakly coordinating anion WCA = [F-{Al(ORF^{F})3_{3}}2_{2}]−^{-}, RF^{F} = C(CF3_{3})3_{3}). The new metalloradical cations with M = Mo and W showcase a similar structural fluxionality as the previously reported [Cr(CO)6_{6}]+^{+}˙. Their reactivity increases from M = Cr < Mo < W and their syntheses allow for in-depth insights into the properties of the group 6 carbonyl triad. Furthermore, the reaction of NO+^{+}[WCA]−^{-} with neutral carbonyl complexes M(CO)6_{6} gives access to the heteroleptic carbonyl/nitrosyl cations [M(CO)5_{5}(NO)]+^{+} as salts of the WCA [Al(ORF)4_{4}]−^{-}, the first complete transition metal triad of their kind

    Structure of Herpes Simplex Virus Glycoprotein D Bound to the Human Receptor Nectin-1

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    Binding of herpes simplex virus (HSV) glycoprotein D (gD) to a cell surface receptor is required to trigger membrane fusion during entry into host cells. Nectin-1 is a cell adhesion molecule and the main HSV receptor in neurons and epithelial cells. We report the structure of gD bound to nectin-1 determined by x-ray crystallography to 4.0 Å resolution. The structure reveals that the nectin-1 binding site on gD differs from the binding site of the HVEM receptor. A surface on the first Ig-domain of nectin-1, which mediates homophilic interactions of Ig-like cell adhesion molecules, buries an area composed by residues from both the gD N- and C-terminal extensions. Phenylalanine 129, at the tip of the loop connecting β-strands F and G of nectin-1, protrudes into a groove on gD, which is otherwise occupied by C-terminal residues in the unliganded gD and by N-terminal residues in the gD/HVEM complex. Notably, mutation of Phe129 to alanine prevents nectin-1 binding to gD and HSV entry. Together these data are consistent with previous studies showing that gD disrupts the normal nectin-1 homophilic interactions. Furthermore, the structure of the complex supports a model in which gD-receptor binding triggers HSV entry through receptor-mediated displacement of the gD C-terminal region

    ENABLING COLLABORATIVE E-HEALTH THROUGH TRIPLESPACE COMPUTING

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    Abstract The design and promotion of electronic patient summaries as an instrument to facilitate the pervasive delivery of healthcare is emerging as a key technology in eHealth solutions. From the technical point of view this requires powerful middleware systems supporting interoperability, multi-lingualism, security and patient privacy. In this paper we present a semantic coordination model and describe how it can be used to support pervasive access to electronic patient summaries

    Electron-Rich EDOT Linkers in Tetracationic bis-Triarylborane Chromophores: Influence on Water Stability, Biomacromolecule Sensing, and Photoinduced Cytotoxicity

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    Three novel tetracationic bis-triarylboranes with 3, 4-ethylenedioxythiophene (EDOT) linkers, and their neutral precursors, showed significant red-shifted absorption and emission compared to their thiophene-containing analogues, with one of the EDOT-derivatives emitting in the NIR region. Only the EDOT-linked trixylylborane tetracation was stable in aqueous solution, indicating that direct attachment of a thiophene or even 3-methylthiophene to the boron atom is insufficient to provide hydrolytic stability in aqueous solution. Further comparative analysis of the EDOT-linked trixylylborane tetracation and its bis-thiophene analogue revealed efficient photo-induced singlet oxygen production, with the consequent biological implications. Thus, both analogues bind strongly to ds-DNA and BSA, very efficiently enter living human cells, accumulate in several different cytoplasmic organelles with no toxic effect but, under intense visible light irradiation, they exhibit almost instantaneous and very strong cytotoxic effects, presumably attributed to singlet oxygen production. Thus, both compounds are intriguing theranostic agents, whose intracellular and probably intra-tissue location can be monitored by strong fluorescence, allowing switching on of the strong bioactivity by well-focused visible light

    Saliency maps for finding changes in visual scenes?

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    Sudden changes in the environment reliably summon attention. This rapid change detection appears to operate in a similar fashion as pop-out in visual search, the phenomenon that very salient stimuli are directly attended, independently of the number of distracting objects. Pop-out is usually explained by the workings of saliency maps, i.e., map-like representations that code for the conspicuity at each location of the visual field. While past research emphasized similarities between pop-out search and change detection, our study highlights differences between the saliency computations in the two tasks: in contrast to pop-out search, saliency computation in change detection (i) operates independently across different stimulus properties (e.g., color and orientation), and (ii) is little influenced by trial history. These deviations from pop-out search are not due to idiosyncrasies of the stimuli or task design, as evidenced by a replication of standard findings in a comparable visual-search design. To explain these results, we outline a model of change detection involving the computation of feature-difference maps, which explains the known similarities and differences with visual search
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