555 research outputs found
Rhombic Patterns: Broken Hexagonal Symmetry
Landau-Ginzburg equations derived to conserve two-dimensional spatial symmetries lead to the prediction that rhombic arrays with characteristic angles slightly differ from 60 degrees should form in many systems. Beyond the bifurcation from the uniform state to patterns, rhombic patterns are linearly stable for a band of angles near the 60 degrees angle of regular hexagons. Experiments conducted on a reaction-diffusion system involving a chlorite-iodide-malonic acid reaction yield rhombic patterns in good accord with the theory.Energy Laboratory of the University of HoustonOffice of Naval ResearchU.S. Department of Energy Office of Basic Energy SciencesRobert A. Welch FoundationCenter for Nonlinear Dynamic
Ionic liquids that form adducts with alcohols
Ionic liquids bearing an activated carbonyl group in the cation are shown to form adducts with alcohols without the aid of any catalysts. How these functionalised ionic liquids could be used in altering vapour phase compositions of alcohols and in alcohol separations are demonstrated.</p
Emergence of Order in Textured Patterns
A characterization of textured patterns, referred to as the disorder function
\bar\delta(\beta), is used to study properties of patterns generated in the
Swift-Hohenberg equation (SHE). It is shown to be an intensive,
configuration-independent measure. The evolution of random initial states under
the SHE exhibits two stages of relaxation. The initial phase, where local
striped domains emerge from a noisy background, is quantified by a power law
decay \bar\delta(\beta) \sim t^{-{1/2} \beta}. Beyond a sharp transition a
slower power law decay of \bar\delta(\beta), which corresponds to the
coarsening of striped domains, is observed. The transition between the phases
advances as the system is driven further from the onset of patterns, and
suitable scaling of time and \bar\delta(\beta) leads to the collapse of
distinct curves. The decay of during the initial phase
remains unchanged when nonvariational terms are added to the underlying
equations, suggesting the possibility of observing it in experimental systems.
In contrast, the rate of relaxation during domain coarsening increases with the
coefficient of the nonvariational term.Comment: 9 Pages, 8 Postscript Figures, 3 gif Figure
Entropic measure of spatial disorder for systems of finite-sized objects
We consider the relative configurational entropy per cell S_Delta as a
measure of the degree of spatial disorder for systems of finite-sized objects.
It is highly sensitive to deviations from the most spatially ordered reference
configuration of the objects. When applied to a given binary image it provides
the quantitatively correct results in comparison to its point object version.
On examples of simple cluster configurations, two-dimensional Sierpinski
carpets and population of interacting particles, the behaviour of S_Delta is
compared with the normalized information entropy H' introduced by Van Siclen
[Phys. Rev. E 56, (1997) 5211]. For the latter example, the additional
middle-scale features revealed by our measure may indicate for the traces of
self-similar structure of the weakly ramified clusters. In the thermodynamic
limit, the formula for S_Delta is also given.Comment: 18 pages, 4 figure
Systematic derivation of a rotationally covariant extension of the 2-dimensional Newell-Whitehead-Segel equation
An extension of the Newell-Whitehead-Segel amplitude equation covariant under
abritrary rotations is derived systematically by the renormalization group
method.Comment: 8 pages, to appear in Phys. Rev. Letters, March 18, 199
Using Nonlinear Response to Estimate the Strength of an Elastic Network
Disordered networks of fragile elastic elements have been proposed as a model
of inner porous regions of large bones [Gunaratne et.al., cond-mat/0009221,
http://xyz.lanl.gov]. It is shown that the ratio of responses of such
a network to static and periodic strain can be used to estimate its ultimate
(or breaking) stress. Since bone fracture in older adults results from the
weakening of porous bone, we discuss the possibility of using as a
non-invasive diagnostic of osteoporotic bone.Comment: 4 pages, 4 figure
Game-changer business models for sustainable development
To address the grand challenges that society faces, incremental change and gradual organizational renewal are not sufficient. A radical transformation of business models is needed. In this paper, we explore game-changer business models that incorporate sustainability principles into their organizational DNA. We draw on two examples from the agrifood sector to illustrate the components of the business model, the impact of Industry 4.0 technologies and the sustainability outcomes. We reinforce the importance of collaboration between policymakers, business leaders and researchers to identify, promote and scale up these business models for transformative societal change
Period Stabilization in the Busse-Heikes Model of the Kuppers-Lortz Instability
The Busse-Heikes dynamical model is described in terms of relaxational and
nonrelaxational dynamics. Within this dynamical picture a diverging alternating
period is calculated in a reduced dynamics given by a time-dependent
Hamiltonian with decreasing energy. A mean period is calculated which results
from noise stabilization of a mean energy. The consideration of
spatial-dependent amplitudes leads to vertex formation. The competition of
front motion around the vertices and the Kuppers-Lortz instability in
determining an alternating period is discussed.Comment: 28 pages, 11 figure
Physiological responses to basic tastes for sensory evaluation of chocolate using biometric techniques
Facial expressions are in reaction to basic tastes by the response to receptor stimulation. The objective of this study was to assess the autonomic nervous system responses to basic tastes in chocolates and to identify relationships between conscious and unconscious responses from participants. Panelists (n = 45) tasted five chocolates with either salt, citric acid, sugar, or monosodium glutamate, which generated four distinctive basic tastes plus bitter, using dark chocolate. An integrated camera system, coupled with the Bio-Sensory application, was used to capture infrared thermal images, videos, and sensory responses. Outputs were used to assess skin temperature (ST), facial expressions, and heart rate (HR) as physiological responses. Sensory responses and emotions elicited during the chocolate tasting were evaluated using the application. Results showed that the most liked was sweet chocolate (9.01), while the least liked was salty chocolate (3.61). There were significant differences for overall liking (p < 0.05) but none for HR (p = 0.75) and ST (p = 0.27). Sweet chocolate was inversely associated with angry, and salty chocolate positively associated with sad. Positive emotion-terms were associated with sweet samples and liking in self-reported responses. Findings of this study may be used to assess novel tastes of chocolate in the industry based on conscious and emotional responses more objectively
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