111,254 research outputs found
Two-dimensional turbulence models
Two-dimensional turbulence models are compared with experimental measurements made using an array of instrumented towers. The spatial correlation coefficient, the two-point spectrum or cross spectrum, and the coherence function are discussed. The prediction techniques in general agree reasonably well with the experimental results. Measurements of the integral length scale however, do not correlate well with the prediction model
Superfluid shells for trapped fermions with mass and population imbalance
We map out the phase diagram of strongly interacting fermions in a potential
trap with mass and population imbalance between the two spin components. As a
unique feature distinctively different from the equal-mass case, we show that
the superfluid here forms a shell structure which is not simply connected in
space. Different types of normal states occupy the trap regions inside and
outside this superfluid shell. We calculate the atomic density profiles, which
provide an experimental signature for the superfluid shell structure.Comment: 4 pages, 3 figure
Statistical Modelling of Information Sharing: Community, Membership and Content
File-sharing systems, like many online and traditional information sharing
communities (e.g. newsgroups, BBS, forums, interest clubs), are dynamical
systems in nature. As peers get in and out of the system, the information
content made available by the prevailing membership varies continually in
amount as well as composition, which in turn affects all peers' join/leave
decisions. As a result, the dynamics of membership and information content are
strongly coupled, suggesting interesting issues about growth, sustenance and
stability.
In this paper, we propose to study such communities with a simple statistical
model of an information sharing club. Carrying their private payloads of
information goods as potential supply to the club, peers join or leave on the
basis of whether the information they demand is currently available.
Information goods are chunked and typed, as in a file sharing system where
peers contribute different files, or a forum where messages are grouped by
topics or threads. Peers' demand and supply are then characterized by
statistical distributions over the type domain.
This model reveals interesting critical behaviour with multiple equilibria. A
sharp growth threshold is derived: the club may grow towards a sustainable
equilibrium only if the value of an order parameter is above the threshold, or
shrink to emptiness otherwise. The order parameter is composite and comprises
the peer population size, the level of their contributed supply, the club's
efficiency in information search, the spread of supply and demand over the type
domain, as well as the goodness of match between them.Comment: accepted in International Symposium on Computer Performance,
Modeling, Measurements and Evaluation, Juan-les-Pins, France, October-200
Modelling the influence of personality and culture on affect and enjoyment in multimedia
Affect is evoked through an intricate relationship between the characteristics of stimuli, individuals, and systems of perception. While affect is widely researched, few studies consider the combination of multimedia system characteristics and human factors together. As such, this paper explores the influence of personality (Five-Factor Model) and cultural traits (Hofstede Model) on the intensity of multimedia-evoked positive and negative affects (emotions). A set of 144 video sequences (from 12 short movie clips) were evaluated by 114 participants from a cross-cultural population, producing 1232 ratings. On this data, three multilevel regression models are compared: a baseline model that only considers system factors; an extended model that includes personality and culture; and an optimistic model in which each participant is modelled. An analysis shows that personal and cultural traits represent 5.6% of the variance in positive affect and 13.6% of the variance in negative affect. In addition, the affect-enjoyment correlation varied across the clips. This suggests that personality and culture play a key role in predicting the intensity of negative affect and whether or not it is enjoyed, but a more sophisticated set of predictors is needed to model positive affect with the same efficacy
A large-scale one-way quantum computer in an array of coupled cavities
We propose an efficient method to realize a large-scale one-way quantum
computer in a two-dimensional (2D) array of coupled cavities, based on coherent
displacements of an arbitrary state of cavity fields in a closed phase space.
Due to the nontrivial geometric phase shifts accumulating only between the
qubits in nearest-neighbor cavities, a large-scale 2D cluster state can be
created within a short time. We discuss the feasibility of our method for scale
solid-state quantum computationComment: 5 pages, 3 figure
Partonic Effects in Heavy Ion Collisions at RHIC
Effects of partonic interactions in heavy ion collisions at RHIC are studied
in a multiphase transport model (AMPT) that includes both initial partonic and
final hadronic interactions.It is found that a large parton scattering cross
section is needed to understand the measured elliptic flow of pions and
two-pion correlation function.Comment: 10 pages, 5 figures, Workshop on Quark and Hadron Dynamics, Budapest,
Hungary, March 3-7, 200
Crumpling wires in two dimensions
An energy-minimal simulation is proposed to study the patterns and mechanical
properties of elastically crumpled wires in two dimensions. We varied the
bending rigidity and stretching modulus to measure the energy allocation,
size-mass exponent, and the stiffness exponent. The mass exponent is shown to
be universal at value . We also found that the stiffness exponent
is universal, but varies with the plasticity parameters and
. These numerical findings agree excellently with the experimental
results
Remark on approximation in the calculation of the primordial spectrum generated during inflation
We re-examine approximations in the analytical calculation of the primordial
spectrum of cosmological perturbation produced during inflation. Taking two
inflation models (chaotic inflation and natural inflation) as examples, we
numerically verify the accuracy of these approximations.Comment: 10 pages, 6 figures, to appear in PR
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