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  • 1
    Electronic Resource
    Electronic Resource
    Effect of electron–hole interaction on electron spin relaxation in GaAs/AlGaAs quantum wells at room temperature (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 3394-3398 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigated electron spin relaxation with respect to the spatial electron–hole separation in GaAs/AlGaAs quantum wells at room temperature. The polarization dependent time-resolved photoluminescence method was used to measure the electron spin relaxation time by applying an electric field perpendicular to the quantum wells. The spin relaxation time had a strong electric field dependence and largely increased with an increase in the spatial electron–hole separation. These results cannot be explained by only the D'yakonov–Perel process, which has often been considered the cause of spin relaxation. We discuss the possible mechanisms that cause the spin relaxation by taking into account the electron–hole exchange interaction. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.372356
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  • 2
    Electronic Resource
    Electronic Resource
    Improvement in ozone tolerance of tobacco plants with an antisense DNA for 1-aminocyclopropane-1-carboxylate synthase (2002)
    Oxford, UK : Blackwell Science, Ltd
    Plant, cell & environment 25 (2002), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Antisense DNA for an ozone-inducible 1-aminocyclopropane-1-carboxylate (ACC) synthase (EC 4.4.1.14; LE-ACS6) from tomato, under the control of the cauliflower mosaic virus 35S promoter, was introduced into tobacco to generate transgenic plants. Lower rates of ozone-induced ethylene production were observed in three of seven transgenic plants than in the wild-type plants. Ozone-induced visible damage was attenuated in these three lines, and the extent of damage was positively related to the level of ozone-induced ethylene production. In the most ozone-resistant line, ozone-induced accumulation of ACC and levels of transcripts for ozone-inducible endogenous ACC synthases were suppressed compared with those in wild-type plants, demonstrating that ozone-inducible ACC synthases have a key role in the expression of leaf damage by ozone exposure. No significant differences in growth and morphology were observed between transgenic and wild-type plants. Stomatal conductance of transgenic plants during ozone exposure was higher than that of wild-type plants. These findings indicate that the introduction of antisense DNA for an ozone-inducible ACC synthase can improve the ozone tolerance of plants without reducing their gas absorption and productivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2002.00862.x
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  • 3
    Electronic Resource
    Electronic Resource
    Initial identification of a phosphoprotein that appears to be involved in the induction of somatic embryogenesis in carrot (2000)
    Springer
    Plant cell reports 19 (2000), S. 739-747 
    Details
    ISSN: 1432-203X
    Keywords: Key wordsDaucus carota ; Embryogenic competence ; Protein phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined changes in the absence versus presence patterns of phosphoproteins with respect to the acquisition of embryogenic competence during somatic embryogenensis in carrot (Daucus carota L.). To characterize a possible correlation between the induction of embryogenic competence and protein phosphorylation, we examined the patterns of protein phosphorylation in embryogenic cells (EC) and non-embryogenic cells (NC) that had lost the ability to form somatic embryos. Two-dimensional polyacrylamide gel electrophoresis and subsequent autoradiography revealed the presence of 31 phosphoproteins in EC but not in NC. Furthermore, when we examined the induction of somatic embryogenesis by certain stress compounds in the absence of phytohormones, we identified one specific phosphoprotein (ECPP-44). ECPP-44 was found to be induced in all treatments that resulted in embryogenic competence. The partial amino acid and nucleotide sequence of ECPP-44 shows partial homology to two dehydrins (ERD10 and ERD14) from Arabidopsis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002999900186
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  • 4
    Electronic Resource
    Electronic Resource
    Genes for phytochrome A in horseradish: isolation of cDNAs and analysis of expression during light-induced formation of adventitious shoots from hairy roots (2000)
    Springer
    Plant cell reports 19 (2000), S. 1212-1218 
    Details
    ISSN: 1432-203X
    Keywords: Keywords Adventitious shoot ; Hairy root ; Phytochrome A ; Horseradish ; Light induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Three cDNAs for phytochrome A (phyA), designated ArPHYA1, ArPHYA2 and ArPHYA3, respectively, were isolated from a cDNA library prepared from proximal parts of the hairy roots of horseradish (Armoracia rusticana). The level of phyA was higher in those parts than in any other parts of hairy roots. The amino acid sequences deduced from the cDNAs were quite similar, with stronger homology to the product of PHYA of Arabidopsis thaliana than to products of genes for phytochromes of many other plant species. Levels of transcripts in roots and tubers were higher than those in leaves and petioles. The levels in hairy roots were highest at the proximal ends and increased with increased duration of culture in darkness. Furthermore, the levels in proximal parts decreased by 25–50% after light irradiation. The elevated levels of transcripts of PHYA genes at the proximal ends of hairy roots are discussed with reference to the light-induced formation of adventitious shoots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990000259
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  • 5
    Electronic Resource
    Electronic Resource
    Calculation of Be in an α-α-Λ Three-Body Model Using the Faddeev Equations (2000)
    Springer
    Few body systems 28 (2000), S. 103-129 
    Details
    ISSN: 1432-5411
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract.  The hypernucleus Be is investigated in an α-α-Λ three-body model using the Faddeev formalism. We use an α-α interaction in which the Pauli-forbidden states are correctly taken into account and we employ some phenomenological potentials between the α and Λ particles. We obtained two bound states for and , and three resonance states of . We studied the properties of these states by calculating the components and the expectation values of the potential for each partial wave. It is found that a few channels dominate in the α (α, Λ) and states, so that the alpha-clusters or the 8Be core are still alive in the nucleus. In a case where the two alpha particles are fixed on an axis the contour plots of the distribution of the Λ particle are shown. With the assistance of these plots one can visually understand that some of them are shell-model-like states while others are well developed cluster-model-like states. For the structure of Be, it is concluded that the Λ particle is loosely coupled in S- and P-wave orbits about the 8Be(0+) and 8Be(2+) core states. Finally, we discuss a redundant state in the Faddeev amplitude which could arise from the treatment of symmetrization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s006010070026
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  • 6
    Electronic Resource
    Electronic Resource
    Partial-Wave Decomposition for Meson-Exchange Currents in Few-Nucleon Systems (2000)
    Springer
    Few body systems 28 (2000), S. 35-63 
    Details
    ISSN: 1432-5411
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract.  We develop an approach for calculating matrix elements of meson-exchange current operators between three-nucleon basis states in -coupling and a three-nucleon bound state. The contributions generated by π- and ρ-exchanges are included into the consideration. The matrix elements are expressed in terms of multiple integrals in momentum space. We apply a technique of partial-wave decompositions and carry out some angular integrations in closed form. Different representations appropriate for numerical calculations are derived for the matrix elements of interest. The momentum dependences of the matrix elements are studied and benchmark results are presented. The approach developed is of interest for investigations of deuteron-proton radiative capture and 3He photo- and electrodisintegration when the interactions in the initial or final states are taken into account by solving the Faddeev equations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s006010070029
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