257 research outputs found

    eCHASE: Exploiting Cultural Heritage using the Semantic Web

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    The eCHASE project is using semantic web technologies to demonstrate sustainable business models based on access and exploitation of digital cultural heritage content at a European level. In this paper we describe the eCHASE project and outline the system architecture

    Oxidative ring expansion of a low-coordinate palladacycle : synthesis of a robust T-shaped alkylpalladium(II) complex

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    The synthesis of an unusual T-shaped alkylpalladium(II) complex featuring a cyclometalated tri-tert-butylphosphineoxide ligand by oxidation of the corresponding cyclometalated tri-tert-butylphosphine complex with PhIO is reported. We speculate that this reaction proceeds by formation of a transient palladium oxo intermediate and there are structural similarities with a late transition metal exemplar: Milstein’s seminal pincer ligated Pt(IV) oxo (Nature 2008, 455, 1093–1096)

    Fifty Years of ISCA: A data-driven retrospective on key trends

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    Computer Architecture, broadly, involves optimizing hardware and software for current and future processing systems. Although there are several other top venues to publish Computer Architecture research, including ASPLOS, HPCA, and MICRO, ISCA (the International Symposium on Computer Architecture) is one of the oldest, longest running, and most prestigious venues for publishing Computer Architecture research. Since 1973, except for 1975, ISCA has been organized annually. Accordingly, this year will be the 50th year of ISCA. Thus, we set out to analyze the past 50 years of ISCA to understand who and what has been driving and innovating computing systems thus far. Our analysis identifies several interesting trends that reflect how ISCA, and Computer Architecture in general, has grown and evolved in the past 50 years, including minicomputers, general-purpose uniprocessor CPUs, multiprocessor and multi-core CPUs, general-purpose GPUs, and accelerators.Comment: 17 pages, 11 figure

    The crystal structure of PD1, a Haemophilus surface fibril domain

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    The Haemophilus surface fibril (Hsf) is an unusually large trimeric autotransporter adhesin (TAA) expressed by the most virulent strains of H. influenzae. Hsf is known to mediate adhesion between pathogen and host, allowing the establishment of potentially deadly diseases such as epiglottitis, meningitis and pneumonia. While recent research has suggested that this TAA might adopt a novel `hairpin-like' architecture, the characterization of Hsf has been limited to in silico modelling and electron micrographs, with no high-resolution structural data available. Here, the crystal structure of Hsf putative domain 1 (PD1) is reported at 3.3 Å resolution. The structure corrects the previous domain annotation by revealing the presence of an unexpected N-terminal TrpRing domain. PD1 represents the first Hsf domain to be solved, and thus paves the way for further research on the `hairpin-like' hypothesis.Peer reviewe

    On the measurement of intensity correlations from laboratory and astronomical sources with SPADs and SNSPDs

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    We describe the performance of detector modules containing silicon single photon avalanche photodiodes (SPADs) and superconducting nanowire single photon detectors (SNSPDs) to be used for intensity interferometry. The SPADs are mounted in fiber-coupled and free-space coupled packages. The SNSPDs are mounted in a small liquid helium cryostat coupled to single mode fiber optic cables which pass through a hermetic feed-through. The detectors are read out with microwave amplifiers and FPGA-based coincidence electronics. We present progress on measurements of intensity correlations from incoherent sources including gas-discharge lamps and stars with these detectors. From the measured laboratory performance of the correlation system, we estimate the sensitivity to intensity correlations from stars using commercial telescopes and larger existing research telescopes. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

    Evaluation of management scenarios for potable water supply using script-based numerical groundwater models of a freshwater lens

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    © 2019 Elsevier B.V. This manuscript version is made available under the CC-BY-NC-ND 4.0 license: http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 24 month embargo from date of publication (February 2019) in accordance with the publisher’s archiving policyChallenges in balancing freshwater demands and the long-term availability of freshwater from small island aquifers warrants responsive management, whereby groundwater conditions guide decisions about pumping rates to avoid well salinization. We evaluate responsive freshwater lens management for the first time, through transient, three-dimensional, dispersive modelling of Bonriki Island (Kiribati). Both responsive- and fixed-management scenarios are explored, including a novel pumping redistribution strategy. Modelling results reveal that responsive management offers superior lens protection, particularly during droughts. Pumping redistribution produced lower salinities but greater lens depletion. All scenarios indicate that the Bonriki lens will continue to decline, consistent with previous shorter-timeframe projections. Lower lens storage losses are attainable by abstracting groundwater at the maximum acceptable salinity, contrary to traditional strategies of seeking the lowest available salinities. The methodology developed in this research provides a blueprint for investigating responsive, “monitor-and-react” management scenarios, which we advocate as best practice for balancing freshwater demands with long-term lens security

    Inhibition of the glucocorticoid‐activating enzyme 11ÎČ‐hydroxysteroid dehydrogenase type 1 drives concurrent 11‐oxygenated androgen excess

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    Aldo‐keto reductase 1C3 (AKR1C3) is a key enzyme in the activation of both classic and 11‐oxygenated androgens. In adipose tissue, AKR1C3 is co‐expressed with 11ÎČ‐hydroxysteroid dehydrogenase type 1 (HSD11B1), which catalyzes not only the local activation of glucocorticoids but also the inactivation of 11‐oxygenated androgens, and thus has the potential to counteract AKR1C3. Using a combination of in vitro assays and in silico modeling we show that HSD11B1 attenuates the biosynthesis of the potent 11‐oxygenated androgen, 11‐ketotestosterone (11KT), by AKR1C3. Employing ex vivo incubations of human female adipose tissue samples we show that inhibition of HSD11B1 results in the increased peripheral biosynthesis of 11KT. Moreover, circulating 11KT increased 2–3 fold in individuals with type 2 diabetes after receiving the selective oral HSD11B1 inhibitor AZD4017 for 35 days, thus confirming that HSD11B1 inhibition results in systemic increases in 11KT concentrations. Our findings show that HSD11B1 protects against excess 11KT production by adipose tissue, a finding of particular significance when considering the evidence for adverse metabolic effects of androgens in women. Therefore, when targeting glucocorticoid activation by HSD11B1 inhibitor treatment in women, the consequently increased generation of 11KT may offset beneficial effects of decreased glucocorticoid activation

    On the resilience of small-island freshwater lenses: Evidence of the long-term impacts of groundwater abstraction on Bonriki Island, Kiribati

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    © 2018 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license: http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 24 month embargo from date of publication (June 2018) in accordance with the publisher’s archiving policy.Groundwater on islands occurs in the form of freshwater lenses that serve as an important water resource for local inhabitants. These lenses are highly vulnerable to salinization due to natural recharge variations and groundwater abstraction. Determining the sustainable yield from freshwater lenses is challenging because the lens response during drought periods and the long-term effects of pumping are both difficult to predict. The exceptionally detailed and long data record for Bonriki Island of the Tarawa atoll (Kiribati) made it possible to develop a three-dimensional variable-density model of the island. Field data and modelling results highlight the strong control of rainfall variability and pumping on the temporal dynamics of the freshwater lens. The model reproduces the salinity observations in both monitoring and pumping wells reasonably well, and provides a rare example of physically based island simulation based on an extensive data set. It enables the analysis of freshwater volume and fluxes of submarine groundwater discharge, which is impossible based on the field observations alone. Under natural as well as abstraction conditions, submarine groundwater discharge responds rapidly and almost proportionally to recharge. Theoretical model scenarios with scaled abstraction rates show that lens contraction caused by pumping is a nearly linear function of the total pumped volume, whereby the abstraction rate and the timing of depletion are approximately inversely proportional. Modelling indicates that when monthly recharge inputs fall below around 2500 m3/d (i.e., a flux of 1.7 mm/d) plus the abstraction rate, the lens tends to contract. Thus, despite the highly distributed and extensive abstraction network on Bonriki Island, a significant amount of recharge is eventually lost to submarine groundwater discharge. The long-term freshwater storage trend indicates that Bonriki Island’s lens is still contracting after 27.5 years of pumping, and lens thinning is threatening to impact the water supply salinity. This means that even permeable, small islands like Bonriki may take at least two decades to realise new equilibrium conditions that reflect pumping stresses, which is an important consideration in assessing the sustainable yield of small islands, in particular those less resilient to pumping than Bonriki

    Unregulated actin polymerization by WASp causes defects of mitosis and cytokinesis in X-linked neutropenia

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    Specific mutations in the human gene encoding the Wiskott-Aldrich syndrome protein (WASp) that compromise normal auto-inhibition of WASp result in unregulated activation of the actin-related protein 2/3 complex and increased actin polymerizing activity. These activating mutations are associated with an X-linked form of neutropenia with an intrinsic failure of myelopoiesis and an increase in the incidence of cytogenetic abnormalities. To study the underlying mechanisms, active mutant WASpI294T was expressed by gene transfer. This caused enhanced and delocalized actin polymerization throughout the cell, decreased proliferation, and increased apoptosis. Cells became binucleated, suggesting a failure of cytokinesis, and micronuclei were formed, indicative of genomic instability. Live cell imaging demonstrated a delay in mitosis from prometaphase to anaphase and confirmed that multinucleation was a result of aborted cytokinesis. During mitosis, filamentous actin was abnormally localized around the spindle and chromosomes throughout their alignment and separation, and it accumulated within the cleavage furrow around the spindle midzone. These findings reveal a novel mechanism for inhibition of myelopoiesis through defective mitosis and cytokinesis due to hyperactivation and mislocalization of actin polymerization
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