33,368 research outputs found
New magic number for neutron rich Sn isotopes
The variation of E(2+_1) of (134-140)Sn calculated with empirical SMPN
interaction has striking similarity with that of experimental E(2+_1) of
even-even (18-22)O and (42-48)Ca, showing clearly that N=84-88 spectra exhibit
the effect of gradual filling up of \nu(2f_{7/2}) orbital which finally
culminates in a new shell closure at N=90. Realistic two-body interaction CWG
does not show this feature. Spin-tensor decomposition of SMPN and CWG
interactions and variation of their components with valence neutron number
reveals that the origin of the shell closure at 140Sn lies in the three body
effects. Calculations with CWG3, which is obtained by including a simple
three-body monopole term in the CWG interaction, predict decreasing E(2+_1) for
(134-138)Sn and a shell closure at 140Sn.Comment: 4 pages, 5 figure
Error-power tradeoffs in QCA design
In this work we present an error-power tradeoff study in a Quantum-dot Cellular Automata (QCA) circuit design. Device parameter variation to optimize performance is a very crucial step in the development of a technology. In this work we vary the maximum kink energy of a QCA circuit to perform an error-power tradeoff study in QCA design. We make use of graphical probabilistic models to estimate polarization errors and non-adiabatic energy dissipated in a clocked QCA circuit and demonstrate the tradeoff studies on the basic QCA circuits such as majority gate and inverter. We also show how this study can be used by comparing two single bit adder designs. The study will be of great use to designers and fabrication scientists to choose the most optimum size and spacing of QCA cells to fabricate QCA logic designs
Abelian-Higgs-Navier-Stokes Hydrodynamics for Nematic Films with Defects
A new theory of hydrodynamics of uniaxial nematic liquid crystal films in the
presence of defects is developed. A gauge field incorporating screening is
introduced, resulting in the static elastic free energy having the form of a
two-dimensional Abelian-Higgs model. Hydrodynamic equations are derived via the
standard methods of de~Groot and Mazur. By working in the vicinity of the
Bogomol'nyi equations consequences for defect centre motion are outlined.Comment: 12 page
PSI to turbulence during internal wave beam refraction through the upper ocean pycnocline
A numerical study based on large eddy simulation (LES) is performed to investigate the nonlinear interaction of a semidiurnal (M2) internal wave beam with an upper ocean pycnocline. During refraction through the pycnocline, the wave beam undergoes parametric subharmonic instability (PSI) with formation of waves with (1/2)M2 frequency. The three-dimensional LES enables new results that quantify the route to turbulence through PSI. The subharmonic waves generated from PSI have an order of magnitude smaller vertical scale and are susceptible to wave breaking. Convective instability initiates transition to turbulence, while shear production maintains it. Turbulence at points in the subharmonic wave paths is modulated at (1/2)M2 frequency. The beam suffers substantial degradation owing to PSI, reflected harmonics and ducted waves so that only about 30% of the incoming energy is transported by the main reflected beam.We are pleased to acknowledge
support through ONR N000140910287,
program manager Terri Paluszkiewicz,
ARC DECRA Fellowship DE140100089
for B.G., and helpful discussions with
Shaun Johnston, SIO
Closed string exchanges on in a background B-field
In an earlier work it was shown that the IR singularities arising in the
nonplanar one loop two point function of a noncommutative gauge
theory can be reproduced exactly from the massless closed string exchanges. The
noncommutative gauge theory is realised on a fractional brane localised
at the fixed point of the orbifold. In this paper we identify the
contributions from each of the closed string modes. The sum of these adds upto
the nonplanar two-point function.Comment: 27 page
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