28,730 research outputs found
Global Fits of the CKM Matrix
We report upon the present status of global fits to Cabibbo-Kobayashi-Maskawa
matrix.Comment: 3 pages, 3 figures invited talk presented at EPS conference, Aachen
July 17-2
Gravity-assisted trajectories for unmanned space exploration
Gravity assistance to modify heliocentric trajectories of manned space probe
Market institutions and urban food supply in West and Southern Africa: a review
As the urban share of Africa‟s population increases, the importance of understanding how food supply is shaped by market institutions has grown. However, this topic has received little attention from policy makers and researchers despite the implications of market institutions and regulatory systems for livelihoods and poverty. This paper reviews the existing literature on market intermediaries, access to selling spaces, finance for traders and sources of information on prices and supplies. The gaps in research are identified and a set of key research issues in this crucial, yet under-researched, area are articulated
Modulated Amplitude Waves in Collisionally Inhomogeneous Bose-Einstein Condensates
We investigate the dynamics of an effectively one-dimensional Bose-Einstein
condensate (BEC) with scattering length subjected to a spatially periodic
modulation, . This "collisionally inhomogeneous" BEC is
described by a Gross-Pitaevskii (GP) equation whose nonlinearity coefficient is
a periodic function of . We transform this equation into a GP equation with
constant coefficient and an additional effective potential and study a
class of extended wave solutions of the transformed equation. For weak
underlying inhomogeneity, the effective potential takes a form resembling a
superlattice, and the amplitude dynamics of the solutions of the
constant-coefficient GP equation obey a nonlinear generalization of the Ince
equation. In the small-amplitude limit, we use averaging to construct
analytical solutions for modulated amplitude waves (MAWs), whose stability we
subsequently examine using both numerical simulations of the original GP
equation and fixed-point computations with the MAWs as numerically exact
solutions. We show that "on-site" solutions, whose maxima correspond to maxima
of , are significantly more stable than their "off-site" counterparts.Comment: 25 pages, 10 figures (many with several parts), to appear in Physica
D; higher resolution versions of some figures are available at
http://www.its.caltech.edu/~mason/paper
Dynamics and Manipulation of Matter-Wave Solitons in Optical Superlattices
We analyze the existence and stability of bright, dark, and gap matter-wave
solitons in optical superlattices. Then, using these properties, we show that
(time-dependent) ``dynamical superlattices'' can be used to controllably place,
guide, and manipulate these solitons. In particular, we use numerical
experiments to displace solitons by turning on a secondary lattice structure,
transfer solitons from one location to another by shifting one superlattice
substructure relative to the other, and implement solitonic ``path-following'',
in which a matter wave follows the time-dependent lattice substructure into
oscillatory motion.Comment: 6 pages, revtex, 6 figures, to appear in Physics Letters A; minor
modifications from last versio
Shuttle operations simulation model programmers'/users' manual
The prospective user of the shuttle operations simulation (SOS) model is given sufficient information to enable him to perform simulation studies of the space shuttle launch-to-launch operations cycle. The procedures used for modifying the SOS model to meet user requirements are described. The various control card sequences required to execute the SOS model are given. The report is written for users with varying computer simulation experience. A description of the components of the SOS model is included that presents both an explanation of the logic involved in the simulation of the shuttle operations cycle and a description of the routines used to support the actual simulation
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