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  • 1
    Electronic Resource
    Electronic Resource
    Random amplified polymorphic DNA markers reveal low genetic variation and a single dominant genotype in Eichhornia crassipes populations throughout China (2005)
    Oxford, UK : Blackwell Science Ltd
    Weed research 45 (2005), S. 0 
    Details
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Genetic variation within and between 34 populations of Eichhornia crassipes (water hyacinth) in China was surveyed using random amplified polymorphic DNA (RAPD) markers. A total of 1009 individuals were analysed, for which 12 RAPD primers amplified 69 reproducible bands, with 22 (32%) being polymorphic. The percentage of polymorphic loci (p) within a population ranged from 4.4% to 17.4%, and the mean Nei's gene diversity (He) was 0.046 ± 0.0145, indicating a low genetic diversity of E. crassipes in China. Each population contained at least four RAPD phenotypes (genotypes), and the same particular genotype was invariably dominant in all the populations sampled. The mean proportion of distinguishable genotypes was 0.29. Analysis of molecular variance revealed a large proportion of genetic variation (83.9%) residing within populations and a slightly larger proportion (88.1%) within localities, indicating a low genetic differentiation of E. crassipes populations, both locally and regionally. Human-mediated dispersal, vigorous clonal growth, and a generally low level of sexual reproduction were thought to be responsible for such a pattern of genetic structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3180.2005.00445.x
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    Paper (German National Licenses)
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  • 2
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    C terminus of Hsc70-interacting protein (CHIP)-mediated degradation of hippocampal estrogen receptor-  and the critical period hypothesis of estrogen neuroprotection (2011)
    National Academy of Sciences
    Details
    Publication Date: 2011-08-01
    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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  • 3
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    A novel approach to correct the coded aperture misalignment for fast neutron imaging (2016)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2016-01-01
    Description: Aperture alignment is crucial for the diagnosis of neutron imaging because it has significant impact on the coding imaging and the understanding of the neutron source. In our previous studies on the neutron imaging system with coded aperture for large field of view, “residual watermark,” certain extra information that overlies reconstructed image and has nothing to do with the source is discovered if the peak normalization is employed in genetic algorithms (GA) to reconstruct the source image. Some studies on basic properties of residual watermark indicate that the residual watermark can characterize coded aperture and can thus be used to determine the location of coded aperture relative to the system axis. In this paper, we have further analyzed the essential conditions for the existence of residual watermark and the requirements of the reconstruction algorithm for the emergence of residual watermark. A gamma coded imaging experiment has been performed to verify the existence of residual watermark. Based on the residual watermark, a correction method for the aperture misalignment has been studied. A multiple linear regression model of the position of coded aperture axis, the position of residual watermark center, and the gray barycenter of neutron source with twenty training samples has been set up. Using the regression model and verification samples, we have found the position of the coded aperture axis relative to the system axis with an accuracy of approximately 20 μ m. Conclusively, a novel approach has been established to correct the coded aperture misalignment for fast neutron coded imaging.
    Print ISSN: 0034-6748
    Electronic ISSN: 1089-7623
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Published by American Institute of Physics (AIP)
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  • 4
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    Asymmetric Ionospheric Outflow Observed at the Dayside Magnetopause (2015)
    Wiley
    Details
    Publication Date: 2015-04-17
    Description: An important source of the terrestrial magnetospheric plasma is the Earth's ionospheric outflows from the high latitude regions of both hemispheres. The ionospheric ion outflows have rarely been observed at the dayside magnetopause. We report Cluster observations of the ionospheric ion outflows observed at the dayside magnetopause. The low-energy (up to 1.5 keV) electrons are detected with bi-directional pitch angle distributions indicating that the magnetic field lines are closed. The unidirectional cold ions (〈200 eV) are observed in the magnetosphere by both C1 and C3. The pitch angle distributions (0°– –75°) of the cold ions (〈1 keV) at the dayside magnetopause indicate that these cold ions are the ionospheric outflows comingonly from the southern hemisphere. The cold ions (〈200 eV) fluxes are modulated by the ULF wave electric field. Two different species (possibly H + and He + ) are observed in the magnetosphere. Our results suggest that the ionospheric outflows can directly reach the dayside magnetopause region and may participate in the reconnection process.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 5
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    C terminus of Hsc70-interacting protein (CHIP)-mediated degradation of hippocampal estrogen receptor-{alpha} and the critical period hypothesis of estrogen neuroprotection [Neuroscience] (2011)
    National Academy of Sciences
    Details
    Publication Date: 2011-08-31
    Description: Recent work suggests that timing of 17β-estradiol (E2) therapy may be critical for observing a beneficial neural effect. Along these lines, E2 neuroprotection, but not its uterotropic effect, was shown to be lost following long-term E2 deprivation (LTED), and this effect was associated with a significant decrease of estrogen receptor-α (ERα) in the hippocampus but not the uterus. The purpose of the current study was to determine the mechanism underlying the ERα decrease and to determine whether aging leads to a similar loss of hippocampal ERα and E2 sensitivity. The results of the study show that ERα in the rat hippocampal CA1 region but not the uterus undergoes enhanced interaction with the E3 ubiquitin ligase C terminus of heat shock cognate protein 70 (Hsc70)-interacting protein (CHIP) that leads to its ubiquitination/proteasomal degradation following LTED (10-wk ovariectomy). E2 treatment initiated before but not after LTED prevented the enhanced ERα-CHIP interaction and ERα ubiquitination/degradation and was fully neuroprotective against global cerebral ischemia. Administration of a proteasomal inhibitor or CHIP antisense oligonucleotides to knock down CHIP reversed the LTED-induced down-regulation of ERα. Further work showed that these observations extended to natural aging, because aged rats showed enhanced CHIP interaction; ubiquitination and degradation of both hippocampal ERα and ERβ; and, importantly, a correlated loss of E2 neuroprotection against global cerebral ischemia. In contrast, E2 administration to middle-aged rats was still capable of exerting neuroprotection. As a whole, the study provides support for a “critical period” for E2 neuroprotection of the hippocampus and provides important insight into the mechanism underlying the critical period.
    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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  • 6
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    Plasma and Energetic Particle Behaviors during Asymmetric Magnetic Reconnection at the Magnetopause (2014)
    Wiley
    Details
    Publication Date: 2014-02-15
    Description: [1]  The factors controlling asymmetric reconnection and the role of the cold plasma population in the reconnection process are two outstanding questions. We present a case study of multipoint Cluster observations demonstrating that the separatrix and flow boundary angles are greater on the magnetosheath than the magnetospheric side of the magnetopause, probably due to the stronger density than magnetic field asymmetry at this boundary. The motion of cold plasmaspheric ions entering the reconnection region differs from that of warmer magnetosheath and magnetospheric ions. In contrast to the warmer ions, which are probably accelerated by reconnection in the diffusion region near the subsolar magnetopause, the colder ions are simply entrained by E × B drifts at high latitudes on the recently reconnected magnetic field lines. This indicates that plasmaspheric ions can sometimes play only a very limited role in asymmetric reconnection, in contrast to previous simulation studies. Three cold ion populations (probably H + , He + , and O + ) appear in the energy spectrum, consistent with ion acceleration to a common velocity.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 7
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    Global ULF waves generated by a hot flow anomaly (2017)
    Wiley
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    Publication Date: 2017-05-18
    Description: Hot flow anomalies (HFAs), which are frequently observed near Earth's bow shock, are phenomena resulting from the interaction between interplanetary discontinuities and Earth's bow shock. Such transient phenomena upstream the bow shock can cause significant deformation of the bow shock and the magnetosphere, generating traveling convection vortices (TCVs), field-aligned currents and ULF waves in the Earth's magnetosphere. A large HFA (4.9 R E ) was observed by Cluster on April 27, 2008. Nearly monochromatic Pc 3 ULF waves generated by the HFA were observed by multiple spacecrafts and ground stations. The ULF waves show characteristics of standing Alfvén waves. The wave power of the poloidal mode of the generated ULF waves is stronger than that of the toroidal mode. Polarization rotation from the poloidal mode to the toroidal mode is also observed. The Pc 3 ULF waves generated by the HFA were observed at dawn, noon, dusk sectors and night side, indicating that the Pc 3 ULF wave response of the magnetosphere to the HFA is global. Our results show that the impact of HFAs to the magnetosphere is much stronger than what we thought before.
    Print ISSN: 0094-8276
    Electronic ISSN: 1944-8007
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 8
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    Method for inferring the axis orientation of cylindrical magnetic flux rope based on single-point measurement (2013)
    Wiley
    Details
    Publication Date: 2013-02-01
    Description: [1]  We develop a new simple method for inferring the orientation of a magnetic flux rope, which is assumed to be a time-independent cylindrically symmetric structure via the direct single-point analysis of magnetic field structure. The model tests demonstrate that, for the cylindrical flux rope regardless of whether it is force-free or not, the method can consistently yield the axis orientation of the flux rope with higher accuracy and stability than the minimum variance analysis of the magnetic field and the Grad-Shafranov reconstruction technique. Moreover, the radial distance to the axis center and the current density can also be estimated consistently. Application to two actual flux transfer events observed by the four satellites of the Cluster mission demonstrates that the method is more appropriate to be used for the inner part of flux rope, which might be closer to the cylindrical structure, showing good agreement with the results obtained from the optimal Grad-Shafranov reconstruction and the least squares technique of Faraday's law, but fails to produce such agreement for the outer satellite that grazes the flux rope. Therefore, the method must be used with caution.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 9
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    A Statistical Study of Plasmaspheric Plumes and Ionospheric Outflows Observed at the Dayside Magnetopause (2016)
    Wiley
    Details
    Publication Date: 2016-01-12
    Description: We present a statistical study of plasmaspheric plumes and ionospheric outflows observed by the Cluster spacecraft near the dayside magnetopause. Plasmaspheric plumes are identified when the low-energy ions (〈 1 keV) with ∼90° pitch angle distributions are observed by the CIS/HIA instrument. The ionospheric outflows are characterized by unidirectional or bidirectional field-aligned pitch angle distributions of low-energy ions observed in the dayside magnetosphere. 43 (10%) plasmaspheric plume events and 32 (7%) ionospheric outflow events were detected out of the 442 times that C3 crossed the dayside magnetopause between 2007 and 2009. The occurrence rate of plumes at duskside is significantly higher than that at dawnside. The occurrence rate of outflows shows a weak dawn-dusk asymmetry. We investigate the dependence of the occurrence rates of plumes and ionospheric outflows on geomagnetic activity and on solar wind/IMF conditions. The plume events tend to occur during southward IMF (duskward solar wind electric field) and moderate geomagnetic activity ( K p = 3, -30 ≤ D s t 〈-10 nT). However, the ionospheric outflow events tend to occur during northward IMF (dawnward solar wind electric field). The ionospheric outflows do not occur when K p = 0, and the occurrence rate of the ionospheric outflows does not have a clear D s t dependence. 75% (46%) of the outflows are observed in the duskside for negative (positive) IMF B y . Conversely, 54% (25%) of the outflows are observed in the dawnside for positive (negative) IMF B y . Finally, the occurrence rates of both plumes and outflows increase with solar wind dynamic pressure.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 10
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    A Statistical Study on Hot Flow Anomaly Current Sheets (2016)
    Wiley
    Details
    Publication Date: 2016-12-10
    Description: Hot flow anomalies (HFAs) are phenomena frequently observed near Earth's bow shock, and form when the interplanetary discontinuities interact with Earth's bow shock. We perform a statistical study to determine what kind of discontinuities are more efficient to generate HFAs. We use strict criteria to identify classic HFAs, excluding similar foreshock phenomena such as spontaneous hot flow anomalies (SHFAs) and foreshock bubbles. Our results show that magnetic field on at least one side of the interplanetary discontinuities has to be connected to the bow shock in order to form HFAs. Discontinuities with large shear angles are more efficient to form HFAs. The thickness of current sheets and the thickness of HFAs are strongly correlated and current sheets with thickness from 1000 km to 3162 km are more efficient to form HFAs. 74% of the HFAs have the electric field pointing toward the current sheet on the leading side. 72% of the HFAs have the electric field pointing toward the current sheet on the trailing side. In addition, the variations of plasma parameters and the magnetic field of HFAs with E inward on both sides are more dramatic than those with E inward on only one side. An HFA is more likely to form when the reflected flow from the bow shock is along the discontinuity.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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