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  • 1
    Electronic Resource
    Electronic Resource
    What is in the intercellular spaces of roots? Evidence from the cryo-analytical-scanning electron microscope (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 87 (1993), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The schizogenous intercellular spaces (i. e. those small spaces formed by cell walls coming apart) in the cortex of the roots of field-grown maize (Zea mays L.) were studied in planed transverse faces of frozen tissue, very lightly etched and coated with Al. The spaces were mostly filled with either fluid or, in the drier roots, with a flaky deposit. This deposit may have been left behind when water was withdrawn, or may have been debris dislodged by the planing. Even in roots with mostly dry spaces, some wet, fluid-filled spaces remained. X-ray microanalysis of the wet spaces revealed that the fluid contained K (average concentration 230 mM, range 50–750 mM) and Ca (average concentration 100 mM, range 15 to 550 mM), and occasionally small amounts of S, P or Cl. No other balancing inorganic anions were detected. Concentrations in the wet intercellular spaces showed considerable variation between one space and the next, and were often quite different from those in the vacuoles of adjacent cells. However, overall the vacuoles of the cells surrounding the spaces showed mean concentrations, and distributions of concentrations, indistinguishable from those of the wet spaces. Analyses of the deposits in the dry spaces were less reliable because of their uneven surface, but the same ions in about the same amounts were found there. The contents of the spaces showed no correlation with either the time of collection of the roots, or with distance from the root tip. Nor was there any change in concentration of these ions in the spaces when the roots were grown for 19 h in distilled water mist. Experiments and evidence are presented suggesting that the observed distribution of ions is probably not an artefact. Pilot experiments showed similar distributions of extracellular ions in roots of barley, Sudan grass and soybean
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1993.tb02507.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of spurious eigenvalues and multiplicities of true eigenvalues using the real-part dual BEM (1999)
    Springer
    Computational mechanics 24 (1999), S. 41-51 
    Details
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The complex-valued dual BEM has been employed by Chen and Chen (1998) to solve the acoustic modes of a cavity with or without a thin partition. A novel method using only the real part of the complex-valued dual BEM was found by Chen (1998) to be equivalent to the dual MRM. However, spurious eigenvalues occur. In this paper, we propose the singular value decomposition technique to filter out spurious eigenvalues and to determine the multiplicity of true eigenvalues by combining the real-part dual equations. Also, the role of the real-part dual BEM for problems with a degenerate boundary is examined. Four examples, including a square cavity with multiple eigenvalues, a rectangular cavity, a rectangular cavity with a zero thickness partition and a rectangular cavity with a partition with finite thickness, are presented to demonstrate the validity of the proposed method. Also, the analytical solution if available, the FEM results obtained by Petyt et al. and obtained using ABAQUS and the experimental measurements are compared with those of the proposed method, and it is found that agreement between them is very good.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004660050436
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  • 3
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    H2O2 induces classical signal transduction [Cell Biology] (2015)
    National Academy of Sciences
    Details
    Publication Date: 2015-10-21
    Description: Reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) govern cellular homeostasis by inducing signaling. H2O2 modulates the activity of phosphatases and many other signaling molecules through oxidation of critical cysteine residues, which led to the notion that initiation of ROS signaling is broad and nonspecific, and thus fundamentally distinct...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 4
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    Intrinsic nonlinear effects of dipole magnets in small rings (2016)
    American Physical Society (APS)
    Details
    Publication Date: 2016-06-04
    Description: Author(s): H. S. Xu, W. H. Huang, C. X. Tang, and S. Y. Lee We find that dynamic aperture depends significantly on the bending radii of dipole magnets when designing a small storage ring for Tsinghua Thomson scattering X-ray source (TTX) mainly because of the nonlinearity of the dipole field. In this paper, we present systematic studies on the intrinsic-geom… [Phys. Rev. Accel. Beams 19, 064001] Published Fri Jun 03, 2016
    Keywords: Single-Particle Dynamics
    Electronic ISSN: 1098-4402
    Topics: Physics
    Published by American Physical Society (APS)
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  • 5
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    Design of a 4.8-m ring for inverse Compton scattering x-ray source (2014)
    American Physical Society (APS)
    Details
    Publication Date: 2014-07-11
    Description: Author(s): H. S. Xu, W. H. Huang, C. X. Tang, and S. Y. Lee In this paper we present the design of a 50 MeV compact electron storage ring with 4.8-meter circumference for the Tsinghua Thomson scattering x-ray source. The ring consists of four dipole magnets with properly adjusted bending radii and edge angles for both horizontal and vertical focusing, and a ... [Phys. Rev. ST Accel. Beams 17, 070101] Published Thu Jul 10, 2014
    Keywords: Low- and Intermediate-Energy Accelerators
    Electronic ISSN: 1098-4402
    Topics: Physics
    Published by American Physical Society (APS)
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  • 6
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    Testing the Titius-Bode law predictions for Kepler multiplanet systems (2014)
    Oxford University Press
    Details
    Publication Date: 2014-06-10
    Description: We use three and half years of Kepler long-cadence data to search for the 97 predicted planets of Bovaird & Lineweaver in 56 of the multiplanet systems, based on a general Titius–Bode (TB) relation. Our search yields null results in the majority of systems. We detect five planetary candidates around their predicted periods. We also find an additional transit signal beyond those predicted in these systems. We discuss the possibility that the remaining predicted planets are not detected in the Kepler data due to their non-coplanarity or small sizes. We find that the detection rate is beyond the lower boundary of the expected number of detections, which indicates that the prediction power of the TB relation in general extrasolar planetary systems is questionable. Our analysis of the distribution of the adjacent period ratios of the systems suggests that the general TB relation may overpredict the presence of planet pairs near the 3:2 resonance.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 7
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    A Jovian planet in an eccentric 11.5 day orbit around HD 1397 discovered by TESS (2019)
    EDP Sciences
    Details
    Publication Date: 2019-03-01
    Description: The Transiting Exoplanet Survey Satellite TESS has begun a new age of exoplanet discoveries around bright host stars. We present the discovery of HD 1397b (TOI-120.01), a giant planet in an 11.54-day eccentric orbit around a bright (V = 7.9) G-type subgiant. We estimate both host star and planetary parameters consistently using EXOFASTv2 based on TESS time-series photometry of transits and radial velocity measurements with CORALIE and MINERVA-Australis. We also present high angular resolution imaging with NaCo to rule out any nearby eclipsing binaries. We find that HD 1397b is a Jovian planet, with a mass of 0.415 ± 0.020 MJ and a radius of 1.026 ± 0.026 RJ. Characterising giant planets in short-period eccentric orbits, such as HD 1397b, is important for understanding and testing theories for the formation and migration of giant planets as well as planet-star interactions.
    Print ISSN: 0004-6361
    Electronic ISSN: 1432-0746
    Topics: Physics
    Published by EDP Sciences
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  • 8
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    High-precision photometry for K2 Campaign 1 (2015)
    Oxford University Press
    Details
    Publication Date: 2015-10-30
    Description: The two reaction wheel K2 mission promises and has delivered new discoveries in the stellar and exoplanet fields. However, due to the loss of accurate pointing, it also brings new challenges for the data reduction processes. In this paper, we describe a new reduction pipeline for extracting high-precision photometry from the K2 data set, and present public light curves for the K2 Campaign 1 target pixel data set. Key to our reduction is the derivation of global astrometric solutions from the target stamps, from which accurate centroids are passed on for high-precision photometry extraction. We extract target light curves for sources from a combined UCAC4 and EPIC catalogue – this includes not only primary targets of the K2 campaign 1, but also any other stars that happen to fall on the pixel stamps. We provide the raw light curves, and the products of various detrending processes aimed at removing different types of systematics. Our astrometric solutions achieve a median residual of ~0.127 arcsec. For bright stars, our best 6.5 h precision for raw light curves is ~20 parts per million (ppm). For our detrended light curves, the best 6.5 h precision achieved is ~15 ppm. We show that our detrended light curves have fewer systematic effects (or trends, or red-noise) than light curves produced by other groups from the same observations. Example light curves of transiting planets and a Cepheid variable candidate, are also presented. We make all light curves public, including the raw and detrended photometry, at http://k2.hatsurveys.org .
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 9
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    Saturation of the magnetorotational instability in the unstratified shearing box with zero net flux: convergence in taller boxes (2016)
    Oxford University Press
    Details
    Publication Date: 2016-01-02
    Description: Previous studies of the non-linear regime of the magnetorotational instability in one particular type of shearing box model – unstratified with no net magnetic flux – find that without explicit dissipation (viscosity and resistivity) the saturation amplitude decreases with increasing numerical resolution. We show that this result is strongly dependent on the vertical aspect ratio of the computational domain L z / L x . When L z / L x 1, we recover previous results. However, when the vertical domain is extended L z / L x 2.5, we find the saturation level of the stress is greatly increased (giving a ratio of stress to pressure α 0.1), and moreover the results are independent of numerical resolution. Consistent with previous results, we find that saturation of the magnetorotational (MRI) in this regime is controlled by a cyclic dynamo which generates patches of strong toroidal field that switches sign on scales of L x in the vertical direction. We speculate that when L z / L x 1, the dynamo is inhibited by the small size of the vertical domain, leading to the puzzling dependence of saturation amplitude on resolution. We show that previous toy models developed to explain the MRI dynamo are consistent with our results, and that the cyclic pattern of toroidal fields observed in stratified shearing box simulations (leading to the so-called butterfly diagram) may also be related. In tall boxes the saturation amplitude is insensitive to whether or not explicit dissipation is included in the calculations, at least for large magnetic Reynolds and Prandtl number. Finally, we show MRI turbulence in tall domains has a smaller critical Pm c , and an extended lifetime compared to L z / L x 1 boxes.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 10
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    Evaluating climate change impacts on the hydrology of watershed in northwestern China using a stepwise-clustered downscaling approach (2016)
    Wiley
    Details
    Publication Date: 2016-10-08
    Description: ABSTRACT In this study, a stepwise-clustered downscaling model (SCDM) is advanced for transferring atmospheric simulation outputs to acquire high-resolution climate projections at a large-scale watershed system. SCDM can operate different temporal resolutions of atmospheric variables with continuous and discrete complexities. SCDM coupling with hydrological model is used for evaluating climate change impacts on hydrology of the Kaidu watershed in northwestern China. The daily and monthly series of large-scale atmospheric simulation outputs for the Kaidu watershed are extracted from the ensemble of GCMs during past, recent and future periods. Results reveal that (1) SCDM is capable of downscaling climate projections for different stations, and can help understand the spatial heterogeneity of climate change, (2) the performance of SCDM is more acceptable for temperature than precipitation, (3) increase trends of T min and T max (minimum and maximum temperatures) from recent to future are projected. Besides, results from multiple downscaled climate change projections are used for driving a daily climate-streamflow hydrological model. Results disclose that the streamflow would increase because temperature change will cause more glacier melt in future.
    Print ISSN: 0899-8418
    Electronic ISSN: 1097-0088
    Topics: Geosciences , Physics
    Published by Wiley
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