583 research outputs found

    Observing \u3ci\u3eCSLA\u3c/i\u3e expression patterns in \u3ci\u3eArabidopsis thaliana\u3c/i\u3e using promoter-GUS fusion analysis

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    Plant cell walls are the world\u27s most abundant source of renewable biomass. Consisting mainly of carbohydrates, including mannans, plant cell walls are vital to humanity as a source of food, health products, and biofuels. Previous research suggests diverse functions of mannans and implicates several members of the CELLULOSE SYNTHASE-LIKE A (CSLA) gene family as mannan synthases, proteins involved in mannan backbone synthesis. Prior research using Arabidopsis thaliana (A. thaliana) cs/a single mutants showed no obvious phenotypic abnormalities, with the exception of cs/a7, which was embryo lethal; however, ectopic expression of CSLA9 complemented the csla7 mutant phenotype, suggesting csla7 and csla9 enzymes make similar carbohydrate products. Additionally, an -81% reduction in inflorescence stem glucomannan content, reduced quantity and growth rate of lateral roots, as well as a reduced susceptibility to Agrobacterium tumefaciens-mediated transformations have been observed in csla9 knockout mutants. Questions regarding the specific biological functions of CSLA proteins await further investigation. Thus, it was hypothesized in A. thaliana, AtCSLAl and AtCSLA9 have unique expression patterns in various tissues during specific stages of development. The expression patterns of the AtCSLA7 and AtCSLA9 genes during plant development were studied in A. thaliana using promoter-GUS fusion analysis. The results demonstrated unique expression patterns of the AtCSLA7 and AtCSLA9 genes, with numerous examples of overlapping expression at specific developmental stages, supporting the hypothesis. Understanding AtCSLA7 and AtCSLA9 gene expression patterns and functions will also improve understanding of the roles of mannan carbohydrates in plants

    An Efficient Beam Steerable Antenna Array Concept for Airborne Applications

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    Deployment of a satellite borne, steerable antenna array with higher directivity and gain in Low Earth Orbit makes sense to reduce ground station complexity and cost, while still maintaining a reasonable link budget. The implementation comprises a digitally beam steerable phased array antenna integrated with a complete system, comprising the antenna, hosting platform, ground station, and aircraft based satellite emulator to facilitate convenient aircraft based testing of the antenna array and ground-space communication link. This paper describes the design, development and initial successful interim testing of the various subsystems. A two element prototype used in this increases the signal-to-noise ratio (SNR) by 3 dB which is corresponding to more than 10 times better bit error rate (BER)

    Microscopic study of 240Pu, mean-field and beyond

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    The influence of exact angular-momentum projection and configuration mixing on properties of a heavy, well-deformed nucleus is discussed for the example of Pu240. Starting from a self-consistent model using Skyrme interactions, we analyze the resulting modifications of the deformation energy, the fission barrier height, the excitation energy of the superdeformed minimum associated with the fission isomer, the structure of the lowest rotational bands with normal deformation and superdeformation, and the corresponding quadrupole moments and transition moments. We present results obtained with the Skyrme interactions SLy4 and SLy6, which have slightly different surface tensions.Comment: 7 pages REVTEX4, 4 figures. accepted for publication in Phys. Rev.

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    Time-dependent approach to many-particle tunneling in one-dimension

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    Employing the time-dependent approach, we investigate a quantum tunneling decay of many-particle systems. We apply it to a one-dimensional three-body problem with a heavy core nucleus and two valence protons. We calculate the decay width for two-proton emission from the survival probability, which well obeys the exponential decay-law after a sufficient time. The effect of the correlation between the two emitted protons is also studied by observing the time evolution of the two-particle density distribution. It is shown that the pairing correlation significantly enhances the probability for the simultaneous diproton decay.Comment: 9 pages, 10 eps figure

    Characterization of a Plain Broadband Textile PIFA

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    Bandwidth characteristic of a wearable antenna is one of the major factors in determining its usability on the human body. In this work, a planar inverted-F antenna (PIFA) structure is proposed to achieve a large bandwidth to avoid serious antenna reflection coefficient detuning when placed in proximity of the body. The proposed structure is designed based on a simple structure, in order to provide practicality in application and maintain fabrication simplicity. Two different types of conductive textiles, namely Pure Copper Polyester Taffeta Fabric (PCPTF) and ShieldIt, are used in order to proof its concept, in comparison with a metallic antenna made from copper foil. The design is spaced and fabricated using a 6 mm thick fleece fabric. To cater for potential fabrication and material measurement inaccuracies, both antennas' performance are also investigated and analyzed with varying physical and material parameters. From this investigation, it is found that the proposed structure's extended bandwidth enabled the antenna to function with satisfactory on-body reflection coefficients, despite unavoidable gain and efficiency reduction

    The interaction of 11Li with 208Pb

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    Background: 11Li is one of the most studied halo nuclei. The fusion of 11Li with 208Pb has been the subject of a number of theoretical studies with widely differing predictions, ranging over four orders of magnitude, for the fusion excitation function. Purpose: To measure the excitation function for the 11Li + 208Pb reaction. Methods: A stacked foil/degrader assembly of 208Pb targets was irradiated with a 11Li beam producing center of target beam energies from above barrier to near barrier energies (40 to 29 MeV). The intensity of the 11Li beam (chopped) was 1250 p/s and the beam on-target time was 34 hours. The alpha-decay of the stopped evaporation residues was detected in a alpha-detector array at each beam energy in the beam-off period (the beam was on for <= 5 ns and then off for 170 ns). Results: The 215At evaporation residues were associated with the fusion of 11Li with 208Pb. The 213,214At evaporation residues were formed by the breakup of 11Li into 9Li + 2n, with the 9Li fusing with 208Pb. The 214At evaporation residue appears to result from a "quasi-breakup" process. Conclusions: Most of 11Li + 208Pb interactions lead to breakup with a small fraction (<= 11%) leading to complete fusion.Comment: 25 pages, 11 figure
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