133 research outputs found

    Minimal triangulation of the 4-cube

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    AbstractIt is known that the 4-dimensional cube can be triangulated by a set of 16 simplices. This note demonstrates that the 4-dimensional cube cannot be triangulated with fewer than 16 simplices

    Observations on a class of nasty linear complementarity problems

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    AbstractEarlier papers by Murty [16] and Fathi [7] have exhibited classes of linear complementarity problems for which the computational effort (number of pivot steps) required to solve them by Lemke's algorithm [13] or Murty's algorithm [15] grows exponentially with the pronlem size (number of variables). In this paper we consider the sequences of complementary bases that arise as these problems are solved by the aforementioned algorithms. There is a natural correspondence between these bases and binary n-vectors through which the basis sequences can be identified with particular hamiltonian paths on the unit n-cube and with the binary Gray code representations of the integers from 0 to 2n-1

    The Thermal Sunyaev-Zel'dovich Effect from Massive, Quiescent 0.5 \leq z \leq 1.5 Galaxies

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    We use combined South Pole Telescope (SPT)+Planck temperature maps to analyze the circumgalactic medium (CGM) encompassing 138,235 massive, quiescent 0.5 \leq z \leq 1.5 galaxies selected from data from the Dark Energy Survey (DES) and Wide-Field Infrared Survey Explorer (WISE). Images centered on these galaxies were cut from the 1.85 arcmin resolution maps with frequency bands at 95, 150, and 220 GHz. The images were stacked, filtered, and fit with a gray-body dust model to isolate the thermal Sunyaev-Zel'dovich (tSZ) signal, which is proportional to the total energy contained in the CGM of the galaxies. We separate these M=1010.9MM_{\star} = 10^{10.9} M_\odot - 1012M10^{12} M_\odot galaxies into 0.1 dex stellar mass bins, detecting tSZ per bin up to 5.6σ5.6\sigma and a total signal-to-noise ratio of 10.1σ10.1\sigma. We also detect dust with an overall signal-to-noise ratio of 9.8σ9.8\sigma, which overwhelms the tSZ at 150GHz more than in other lower-redshift studies. We correct for the 0.160.16 dex uncertainty in the stellar mass measurements by parameter fitting for an unconvolved power-law energy-mass relation, Etherm=Etherm,peak(M/M,peak)αE_{\rm therm} = E_{\rm therm,peak} \left(M_\star/M_{\star,{\rm peak}} \right)^\alpha, with the peak stellar mass distribution of our selected galaxies defined as M,peak=2.3×1011MM_{\star,{\rm peak}}= 2.3 \times 10^{11} M_\odot. This yields an Etherm,peak=5.981.00+1.02×1060E_{\rm therm,peak}= 5.98_{-1.00}^{+1.02} \times 10^{60} erg and α=3.770.74+0.60\alpha=3.77_{-0.74}^{+0.60}. These are consistent with z0z \approx 0 observations and within the limits of moderate models of active galactic nuclei (AGN) feedback. We also compute the radial profile of our full sample, which is similar to that recently measured at lower-redshift by Schaan et al. (2021).Comment: 23 pages, 9 figures, Accepted for publication in ApJ. Updated to reflect minor change

    The re-birth of the "beat": A hyperlocal online newsgathering model

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    This is an Author's Accepted Manuscript of an article published in Journalism Practice, 6(5-6), 754 - 765, 2012, copyright Taylor & Francis, available online at: http://www.tandfonline.com/10.1080/17512786.2012.667279.Scholars have long lamented the death of the 'beat' in news journalism. Today's journalists generate more copy than they used to, a deluge of PR releases often keeping them in the office, and away from their communities. Consolidation in industry has dislodged some journalists from their local sources. Yet hyperlocal online activity is thriving if journalists have the time and inclination to engage with it. This paper proposes an exploratory, normative schema intended to help local journalists systematically map and monitor their own hyperlocal online communities and contacts, with the aim of re-establishing local news beats online as networks. This model is, in part, technologically-independent. It encompasses proactive and reactive news-gathering and forward planning approaches. A schema is proposed, developed upon suggested news-gathering frameworks from the literature. These experiences were distilled into an iterative, replicable schema for local journalism. This model was then used to map out two real-world 'beats' for local news-gathering. Journalists working within these local beats were invited to trial the models created. It is hoped that this research will empower journalists by improving their information auditing, and could help re-define journalists' relationship with their online audiences

    Thermobarometry of the Moine and Sgurr Beag thrust sheets, northern Scotland

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    In the Caledonides of northern Scotland temperatures of metamorphism (Tm) and deformation (Td) progressively increase structurally up section in the Moine thrust sheet at the foreland edge of the Scandian (mid Silurian) orogenic wedge. However, the thermal history of the structurally overlying, more hinterland positioned thrust sheets is less well known. This study focuses on determining Td and Tm for both the central/upper part of the Moine thrust sheet and the lower part of the overlying Sgurr Beag thrust sheets in the middle of the Northern Highlands Terrane. Preserved microstructures and quartz c-axis fabric opening angles in the Moine and Sgurr Beag thrust sheets imply Td of 460 °C to 605 °C ± 50 °C. Thermobarometry and pseudosection-based P-T constraints, indicate Tm of ∼550–680 °C at 4.8–7.2 kbar in the Moine thrust sheet and Tm of ∼620 °C at 5.6–7.7 kbar in the Sgurr Beag thrust sheet. Together, Td and Tm in the Moine and Sgurr Beag thrust sheets indicate that deformation continued after peak metamorphic conditions in the Sgurr Beag thrust sheet. Monazite and xenotime petrochronology show that Tm, and possibly Td, record Precambrian metamorphism. Peak metamorphism is associated with the Knoydartian orogenic event (840-720 Ma), with possible reworking during Scandian thrusting (430-425 Ma)

    A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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    Bovine Host Genetic Variation Influences Rumen Microbial Methane Production with Best Selection Criterion for Low Methane Emitting and Efficiently Feed Converting Hosts based on Metagenomic Gene Abundance

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    Methane produced by methanogenic archaea in ruminants contributes significantly to anthropogenic greenhouse gas emissions. The host genetic link controlling microbial methane production is unknown and appropriate genetic selection strategies are not developed. We used sire progeny group differences to estimate the host genetic influence on rumen microbial methane production in a factorial experiment consisting of crossbred breed types and diets. Rumen metagenomic profiling was undertaken to investigate links between microbial genes and methane emissions or feed conversion efficiency. Sire progeny groups differed significantly in their methane emissions measured in respiration chambers. Ranking of the sire progeny groups based on methane emissions or relative archaeal abundance was consistent overall and within diet, suggesting that archaeal abundance in ruminal digesta is under host genetic control and can be used to genetically select animals without measuring methane directly. In the metagenomic analysis of rumen contents, we identified 3970 microbial genes of which 20 and 49 genes were significantly associated with methane emissions and feed conversion efficiency respectively. These explained 81% and 86% of the respective variation and were clustered in distinct functional gene networks. Methanogenesis genes (e.g. mcrA and fmdB) were associated with methane emissions, whilst host-microbiome cross talk genes (e.g. TSTA3 and FucI) were associated with feed conversion efficiency. These results strengthen the idea that the host animal controls its own microbiota to a significant extent and open up the implementation of effective breeding strategies using rumen microbial gene abundance as a predictor for difficult-to-measure traits on a large number of hosts. Generally, the results provide a proof of principle to use the relative abundance of microbial genes in the gastrointestinal tract of different species to predict their influence on traits e.g. human metabolism, health and behaviour, as well as to understand the genetic link between host and microbiome
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