495 research outputs found
Characterization of Rice (Oryza sativa L.) Roots Versus Root Pulling Resistance as Selection Indices for Draught Tolerance
A technique described as Root Pulling Resistance (RPR) was used to evaluate genotypic differences in root growth and development of 50 rice germplasm accessions and cultivars. Several root characteristics in rice are associated with drought tolerance and avoidance capability of plants. The RPR measurements showed a significant positive correlation with maximum root length (r=0.69), root thickness (r=0.75), branching number (r=0.75), and root dry weight (r= 0.82). Rice genotypes that had a high RPR value were identified as having longer, thicker, and denser root systems. The data indicated that high RPR measurements are strongly correlated with greater root penetration. Munji Sufaid Pak, IR52 (IR5853-1 18-5) and Saunfia or Mabla Pak 329 had a significantly greater root length, root thickness, root number, root branching and dry weight as compared to IR 36. Also, there was no correlation between plant height and RPR. Furthermore, the data demonstrated that the RPR technique is ideal for selecting superior root systems and potential drought tolerant rice germplasm and cultivars
Espectroscopia de RMN-eletroquĂmica de alta resolução: uma tĂ©cnica in situ para monitoramento de reação.
Ratchet potential for fluxons in Josephson-Junction arrays
We propose a simple configuration of a one-dimensional parallel array of
Josephson junctions in which the pinning potential for trapped fluxons lacks
inversion symmetry (ratchet potential). This sytem can be modelised by a set of
non-linear pendula with alternating lengths and harmonic couplings. We show, by
molecular dynamics simulations, that fluxons behave as single particles in
which the predictions for overdamped thermal ratchet can be easily verified.Comment: 7 pages, 8 figure
Decoherence of the Superconducting Persistent Current Qubit
Decoherence of a solid state based qubit can be caused by coupling to
microscopic degrees of freedom in the solid. We lay out a simple theory and use
it to estimate decoherence for a recently proposed superconducting persistent
current design. All considered sources of decoherence are found to be quite
weak, leading to a high quality factor for this qubit.Comment: 10 pages, 1 figure, Latex/revtex.To appear in proceedings of the
NATO-ASI on "Quantum Mesoscopic Phenomena and Mesoscopic Devices in
Microelectronics"; Corrections were made on Oct. 29th, 199
Cliques and duplication-divergence network growth
A population of complete subgraphs or cliques in a network evolving via
duplication-divergence is considered. We find that a number of cliques of each
size scales linearly with the size of the network. We also derive a clique
population distribution that is in perfect agreement with both the simulation
results and the clique statistic of the protein-protein binding network of the
fruit fly. In addition, we show that such features as fat-tail degree
distribution, various rates of average degree growth and non-averaging,
revealed recently for only the particular case of a completely asymmetric
divergence, are present in a general case of arbitrary divergence.Comment: 7 pages, 6 figure
Phases of Josephson Junction Ladders
We study a Josephson junction ladder in a magnetic field in the absence of
charging effects via a transfer matrix formalism. The eigenvalues of the
transfer matrix are found numerically, giving a determination of the different
phases of the ladder. The spatial periodicity of the ground state exhibits a
devil's staircase as a function of the magnetic flux filling factor . If the
transverse Josephson coupling is varied a continuous superconducting-normal
transition in the transverse direction is observed, analogous to the breakdown
of the KAM trajectories in dynamical systems.Comment: 12 pages with 3 figures, REVTE
Construção de uma cĂ©lula RMN-eletroquĂmica de alta resolução para estudos espectroeletroquĂmicos in situ.
Spatiotemporal dynamics of discrete sine-Gordon lattices with sinusoidal couplings
The spatiotemporal dynamics of a damped sine-Gordon chain with sinusoidal
nearest-neighbor couplings driven by a constant uniform force are discussed.
The velocity characteristics of the chain versus the external force is shown.
Dynamics in the high- and low-velocity regimes are investigated. It is found
that in the high-velocity regime, the dynamics is dominated by rotating modes,
the velocity shows a branching bifurcation feature, while in the low-velocity
regime, the velocity exhibits step-like dynamical transitions, broken by the
destruction of strong resonances.Comment: 10 Revtex pages, 8 Eps figures, to appear in Phys. Rev.E 57(1998
Influence of Hydrodynamic Interactions on Mechanical Unfolding of Proteins
We incorporate hydrodynamic interactions in a structure-based model of
ubiquitin and demonstrate that the hydrodynamic coupling may reduce the peak
force when stretching the protein at constant speed, especially at larger
speeds. Hydrodynamic interactions are also shown to facilitate unfolding at
constant force and inhibit stretching by fluid flows.Comment: to be published in Journal of Physics: Condensed Matte
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