7,038 research outputs found

    Arthropod diversity in peas with normal or reduced waxy bloom

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    Crop traits can alter economically important interactions between plants, pests, and biological control agents. For example, a reduced waxy bloom on the surface of pea plants alters interactions between pea aphids and their natural enemies. In this study, we assess whether the effect of wax reduction extends beyond the 2 or 3 arthropod species closely associated with the plants and into the structure of the broader arthropod community of over 200 taxa at our site. We sampled arthropods on lines of peas with normal and reduced wax in Latah Co., Idaho using pitfall traps within randomly assigned pairs of 5 × 5 meter plots. During the 1998 and 1999 growing seasons, we collected 12,113 individual arthropods from 221 unambiguously identified morphospecies. The number of individuals collected from each morphospecies responded idiosyncratically to the reduced wax peas. To test whether arthropod community structure differed between the collections from plots having peas with normal or reduced wax, we performed a randomization test. The collection from peas with reduced wax had higher species evenness and thus higher community diversity despite having lower species richness. Our results demonstrate the potential of a single plant trait, epicuticular wax, to affect a community of arthropods. Two pests of peas had opposite responses to peas with reduced wax. The number of pea aphids collected was greater from peas with normal wax peas than those with reduced wax. In contrast, the number of pea leaf weevils collected was greater from peas with reduced wax

    Tetrahedral-Mesh Simulation of Turbulent Flows with the Space-Time Conservative Schemes

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    Direct numerical simulations of turbulent flows are predominantly carried out using structured, hexahedral meshes despite decades of development in unstructured mesh methods. Tetrahedral meshes offer ease of mesh generation around complex geometries and the potential of an orientation free grid that would provide un-biased small-scale dissipation and more accurate intermediate scale solutions. However, due to the lack of consistent multi-dimensional numerical formulations in conventional schemes for triangular and tetrahedral meshes at the cell interfaces, numerical issues exist when flow discontinuities or stagnation regions are present. The space-time conservative conservation element solution element (CESE) method - due to its Riemann-solver-free shock capturing capabilities, non-dissipative baseline schemes, and flux conservation in time as well as space - has the potential to more accurately simulate turbulent flows using unstructured tetrahedral meshes. To pave the way towards accurate simulation of shock/turbulent boundary-layer interaction, a series of wave and shock interaction benchmark problems that increase in complexity, are computed in this paper with triangular/tetrahedral meshes. Preliminary computations for the normal shock/turbulence interactions are carried out with a relatively coarse mesh, by direct numerical simulations standards, in order to assess other effects such as boundary conditions and the necessity of a buffer domain. The results indicate that qualitative agreement with previous studies can be obtained for flows where, strong shocks co-exist along with unsteady waves that display a broad range of scales, with a relatively compact computational domain and less stringent requirements for grid clustering near the shock. With the space-time conservation properties, stable solutions without any spurious wave reflections can be obtained without a need for buffer domains near the outflow/farfield boundaries. Computational results for the isotropic turbulent flow decay, at a relatively high turbulent Mach number, show a nicely behaved spectral decay rate for medium to high wave numbers. The high-order CESE schemes offer very robust solutions even with the presence of strong shocks or widespread shocklets. The explicit formulation in conjunction with a close to unity theoretical upper Courant number bound has the potential to offer an efficient numerical framework for general compressible turbulent flow simulations with unstructured meshes

    The Molecular Basis of Selective Permeability of Connexins is Complex and Includes Both Size And Charge

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    Although gap junction channels are still widely viewed as large, non-specific pores connecting cells, the diversity in the connexin family has led more attention to be focused on their permeability characteristics. We summarize here the current status of these investigations, both published and on-going, that reveal both charge and size selectivity between gap junction channels composed of different connexins. In particular, this review will focus on quantitative approaches that monitor the expression level of the connexins, so that it is clear that differences that are seen can be attributed to channel properties. The degree of selectivity that is observed is modest compared to other channels, but is likely to be significant for biological molecules that are labile within the cell. Of particular relevance to the in vivo function of gap junctions, recent studies are summarized that demonstrate that the connexin phenotype can control the nature of the endogenous traffic between cells, with consequent effects on biological effects of gap junctions such as tumor suppression

    CLASP promotes microtubule rescue by recruiting tubulin dimers to the microtubule

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    Spatial regulation of microtubule (MT) dynamics contributes to cell polarity and cell division. MT rescue, in which a MT stops shrinking and reinitiates growth, is the least understood aspect of MT dynamics. Cytoplasmic Linker Associated Proteins (CLASPs) are a conserved class of MT-associated proteins that contribute to MT stabilization and rescue in vivo. We show here that the Schizosaccharomyces pombe CLASP, Cls1p, is a homodimer that binds an αβ-tubulin heterodimer through conserved TOG-like domains. In vitro, CLASP increases MT rescue frequency, decreases MT catastrophe frequency, and moderately decreases MT disassembly rate. CLASP binds stably to the MT lattice, recruits tubulin, and locally promotes rescues. Mutations in the CLASP TOG domains demonstrate that tubulin binding is critical for its rescue activity. We propose a mechanism for rescue in which CLASP-tubulin dimer complexes bind along the MT lattice and reverse MT depolymerization with their bound tubulin dimer

    CLASP promotes microtubule rescue by recruiting tubulin dimers to the microtubule

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    Spatial regulation of microtubule (MT) dynamics contributes to cell polarity and cell division. MT rescue, in which a MT stops shrinking and reinitiates growth, is the least understood aspect of MT dynamics. Cytoplasmic Linker Associated Proteins (CLASPs) are a conserved class of MT-associated proteins that contribute to MT stabilization and rescue in vivo. We show here that the Schizosaccharomyces pombe CLASP, Cls1p, is a homodimer that binds an αβ-tubulin heterodimer through conserved TOG-like domains. In vitro, CLASP increases MT rescue frequency, decreases MT catastrophe frequency, and moderately decreases MT disassembly rate. CLASP binds stably to the MT lattice, recruits tubulin, and locally promotes rescues. Mutations in the CLASP TOG domains demonstrate that tubulin binding is critical for its rescue activity. We propose a mechanism for rescue in which CLASP-tubulin dimer complexes bind along the MT lattice and reverse MT depolymerization with their bound tubulin dimer

    Failure Mode Analysis of the Endologix Endograft

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    Objective Type III (T-III) endoleaks following endovascular aneurysm repair (EVAR) remain a major concern. Our center experienced a recent concentration of T-III endoleaks requiring elective and emergency treatment and prompted our review of all EVAR implants over a 40-month period from April 2011 until August 2014. This report represents a single center experience with T-III endoleak management with analysis of factors leading to the T-III-related failure of EVAR. Methods A retrospective review of all the operative reports, medical records, and computed tomography scans were reviewed from practice surveillance. Using Society for Vascular Surgery aneurysm reporting standards, we analyzed the morphology of the aneurysms before and after EVAR implant using computed tomography. Index procedure and frequency of reinterventions required to maintain aneurysm freedom from rupture were compared across all devices using SAS v 9.4 (SAS Institute, Inc, Cary, NC). Major adverse events (MAEs) requiring secondary interventions for aneurysm treatment beyond primary implant were analyzed for methods of failure. Aneurysm morphology of patients requiring EVAR was compared across all endograft devices used for repair. For purposes of MAE analysis, patients receiving Endologix (ELX) endograft were combined into group 1; Gore, Cook, and Medtronic endograft patients were placed into group 2. Results Overall, technical success and discharge survival were achieved in 97.3% and 98% of patients regardless of device usage. There was no significant device related difference identified between patient survival or freedom from intervention. MAEs involving aneurysm treatment were over seven-fold more frequent with ELX (group 1) vs non-ELX (group 2) endografts (P < .01). Group 1 patients with aneurysm diameters larger than 65 mm were associated with a highly significant value for development of a T-III endoleak (odds ratio, 11.16; 95% confidence interval, 2.17, 57.27; P = .0038). Conclusions While EVAR technical success and survival were similar across all devices, ELX devices exhibited an unusually high incidence of T-III endoleaks when implanted in abdominal aortic aneurysms with a diameter of more than 65 mm. Frequent reinterventions were required for Endologix devices for prevention of aneurysm rupture due to T-III endoleaks

    SkyMapper Southern Survey: First Data Release (DR1)

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    We present the first data release (DR1) of the SkyMapper Southern Survey, a hemispheric survey carried out with the SkyMapper Telescope at Siding Spring Observatory in Australia. Here, we present the survey strategy, data processing, catalogue construction and database schema. The DR1 dataset includes over 66,000 images from the Shallow Survey component, covering an area of 17,200 deg2^2 in all six SkyMapper passbands uvgrizuvgriz, while the full area covered by any passband exceeds 20,000 deg2^2. The catalogues contain over 285 million unique astrophysical objects, complete to roughly 18 mag in all bands. We compare our grizgriz point-source photometry with PanSTARRS1 DR1 and note an RMS scatter of 2%. The internal reproducibility of SkyMapper photometry is on the order of 1%. Astrometric precision is better than 0.2 arcsec based on comparison with Gaia DR1. We describe the end-user database, through which data are presented to the world community, and provide some illustrative science queries.Comment: 31 pages, 19 figures, 10 tables, PASA, accepte
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