58,245 research outputs found
Amplitude expansion of the binary phase field crystal model
Amplitude representations of a binary phase field crystal model are developed
for a two dimensional triangular lattice and three dimensional BCC and FCC
crystal structures. The relationship between these amplitude equations and the
standard phase field models for binary alloy solidification with elasticity are
derived, providing an explicit connection between phase field crystal and phase
field models. Sample simulations of solute migration at grain boundaries,
eutectic solidification and quantum dot formation on nano-membranes are also
presented.Comment: 11 pages, 8 figure
Bright solitary waves in a Bose-Einstein condensate and their interactions
We examine the dynamics of two bright solitary waves with a negative
nonlinear term. The observed repulsion between two solitary waves -- when these
are in an antisymmetric combination -- is attributed to conservation laws.
Slight breaking of parity, in combination with weak relaxation of energy, leads
the two solitary waves to merge. The effective repulsion between solitary waves
requires certain nearly ideal conditions and is thus fragile.Comment: 6 pages, 14 figure
Theoretical study of ionization of an alkali atom adsorbed on a metal surface by laser assisted subfemtosecond pulse
The first numerical simulation of the process of ionization of an atom
adsorbed on a metal surface by the subfemtosecond pulse is presented. The
streaking scheme is considered, when a weak sub-femtosecond pulse comes
together with a strong IR pulse with a variable delay between them. The problem
is analyzed with numerical solving the non-stationary Schroedinger equation in
the cylindrical coordinate. The results obtained are compared with ones in the
gas phase. We show that the surface influences the DDCS, but the observation of
this influence, beside the trivial polarization shift of the energy of the
initial state, requires a quite high experimental resolution
Dopant Induced Stabilization of Silicon Cluster at Finite Temperature
With the advances in miniaturization, understanding and controlling
properties of significant technological systems like silicon in nano regime
assumes considerable importance. It turns out that small silicon clusters in
the size range of 15-20 atoms are unstable upon heating and in fact fragment in
the temperature range of 1200 K to 1500 K. In the present work we demonstrate
that it is possible to stabilize such clusters by introducing appropriate
dopant (in this case Ti). Specifically, by using the first principle density
functional simulations we show that Ti doped Si, having the Frank-Kasper
geometry, remains stable till 2200 K and fragments only above 2600 K. The
observed melting transition is a two step process. The first step is initiated
by the surface melting around 600 K. The second step is the destruction of the
cage which occurs around 2250 K giving rise to a peak in the heat capacity
curve.Comment: 6 pages, 8 Figs. Submitted to PR
Carrier extraction circuit
Feedback loop extracts demodulated reference signals from IF input and feeds signal back to demodulator. Since reference signal is extracted directly from carrier, no separate reference need be transmitted. Circuit obtains coherent carrier from balanced or unbalanced four-phase signal of varying characteristics
Draft genome sequence of "Candidatus Cronobacter colletis" NCTC 14934T, a new species in the genus Cronobacter
Members of the Cronobacter genus are associated with serious infections in neonates. This is the first report of the draft genome sequence for the newly proposed species Cronobacter colletis
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