40,865 research outputs found
Molecular dynamics study of nanoparticle stability at liquid interfaces : effect of nanoparticle-solvent interaction and capillary waves
While the interaction of colloidal particles (sizes in excess of 100 nm) with liquid interfaces may be understood in terms of continuum models, which are grounded in macroscopic properties such as surface and line tensions, the behaviour of nanoparticles at liquid interfaces may be more complex. Recent simulations [D. L. Cheung and S. A. F. Bon, Phys. Rev. Lett. 102, 066103 (2009)] of nanoparticles at an idealised liquid-liquid interface showed that the nanoparticle-interface interaction range was larger than expected due, in part, to the action of thermal capillary waves. In this paper, molecular dynamics simulations of a Lennard-Jones nanoparticle in a binary Lennard-Jones mixture are used to confirm that these previous results hold for more realistic models. Furthermore by including attractive interactions between the nanoparticle and the solvent, it is found that the detachment energy decreases as the nanoparticle-solvent attraction increases. Comparison between the simulation results and recent theoretical predictions [H. Lehle and M. Oettel, J. Phys. Condens. Matter 20, 404224 (2008)] shows that for small particles the incorporation of capillary waves into the predicted effective nanoparticle-interface interaction improves agreement between simulation and theory
Cellular Automata as a Model of Physical Systems
Cellular Automata (CA), as they are presented in the literature, are abstract
mathematical models of computation. In this pa- per we present an alternate
approach: using the CA as a model or theory of physical systems and devices.
While this approach abstracts away all details of the underlying physical
system, it remains faithful to the fact that there is an underlying physical
reality which it describes. This imposes certain restrictions on the types of
computations a CA can physically carry out, and the resources it needs to do
so. In this paper we explore these and other consequences of our
reformalization.Comment: To appear in the Proceedings of AUTOMATA 200
An Integrative Analysis of Business Bankruptcy in Australia.
This paper proposes an integrative and dynamic approach for analyzing business failure. The simulaneous estimation results obtained with Australian data indicate significant associations between bankruptcy rates in different industries. Most of these associations are positive and hence implying that bankruptcy in one industry can inflict a "domino" effect on other industries.BANKRUPTCY
Models of Quantum Cellular Automata
In this paper we present a systematic view of Quantum Cellular Automata
(QCA), a mathematical formalism of quantum computation. First we give a general
mathematical framework with which to study QCA models. Then we present four
different QCA models, and compare them. One model we discuss is the traditional
QCA, similar to those introduced by Shumacher and Werner, Watrous, and Van Dam.
We discuss also Margolus QCA, also discussed by Schumacher and Werner. We
introduce two new models, Coloured QCA, and Continuous-Time QCA. We also
compare our models with the established models. We give proofs of computational
equivalence for several of these models. We show the strengths of each model,
and provide examples of how our models can be useful to come up with
algorithms, and implement them in real-world physical devices
Possible persistent current in a ring made of the perfect crystalline insulator
A mesoscopic conducting ring pierced by magnetic flux is known to support the
persistent electron current. Here we propose possibility of the persistent
current in the ring made of the perfect crystalline insulator. We consider a
ring-shaped lattice of one-dimensional "atoms" with a single energy level. We
express the Bloch states in the lattice as a linear combination of atomic
orbitals. The discrete energy level splits into the energy band which serves as
a simple model of the valence band. We show that the insulating ring (with the
valence band fully filled by electrons) supports a nonzero persistent current,
because each atomic orbital overlaps with its own tail when making one loop
around the ring. In the tight-binding limit only the neighboring orbitals
overlap. In that limit the persistent current at full filling becomes zero
which is a standard result.Comment: Conference proceedings. Accepted for publication in Physica
Supersonic airplane design optimization method for aerodynamic performance and low sonic boom
This paper presents a new methodology for the optimization of supersonic airplane designs to meet the dual design objectives of low sonic boom and high aerodynamic performance. Two sets of design parameters are used on an existing High Speed Civil Transport (HSCT) configuration to maximize the aerodynamic performance and minimize the sonic boom under the flight track. One set of the parameters perturbs the camber line of the wing sections to maximize the lift-over-drag ratio (L/D). A preliminary optimization run yielded a 3.75 percent improvement in L/D over a baseline low-boom configuration. The other set of parameters modifies the fuselage area to achieve a target F-function. Starting from an initial configuration with strong bow, wing, and tail shocks, a modified design with a flat-top signature is obtained. The methods presented can easily incorporate other design variables and objective functions. Extensions to the present capability in progress are described
(Extra)Ordinary Gauge Mediation
We study models of "(extra)ordinary gauge mediation," which consist of taking
ordinary gauge mediation and extending the messenger superpotential to include
all renormalizable couplings consistent with SM gauge invariance and an
R-symmetry. We classify all such models and find that their phenomenology can
differ significantly from that of ordinary gauge mediation. Some highlights
include: arbitrary modifications of the squark/slepton mass relations, small mu
and Higgsino NLSP's, and the possibility of having fewer than one effective
messenger. We also show how these models lead naturally to extremely simple
examples of direct gauge mediation, where SUSY and R-symmetry breaking occur
not in a hidden sector, but due to the dynamics of the messenger sector itself.Comment: 50 pages, 11 figure
Learning-Related Values in Young Children’s Storybooks: An Investigation in the United States, China, and Mexico
This research examined the prevalence of learning-related values in children’s storybooks in the United States, China, and Mexico. Storybooks ( N = 157) were randomly selected from government-recommended booklists in each country. Trained coders assessed the prevalence of learning-related beliefs (e.g., malleability of ability), motivated cognitions (e.g., achievement orientation), and behaviors (e.g., effort) in the storybooks. A set of MANOVAs revealed that Chinese (vs. American and Mexican) storybooks contained more instances of learning-related beliefs and behaviors. For example, Chinese storybooks included more instances of achievement-related goals and behaviors, relative to storybooks in the United States and Mexico. With the exception of achievement goals and helplessness, the prevalence of learning-related qualities was largely similar in the United States and Mexico
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