39,978 research outputs found
Dynamic Facial Expression of Emotion Made Easy
Facial emotion expression for virtual characters is used in a wide variety of
areas. Often, the primary reason to use emotion expression is not to study
emotion expression generation per se, but to use emotion expression in an
application or research project. What is then needed is an easy to use and
flexible, but also validated mechanism to do so. In this report we present such
a mechanism. It enables developers to build virtual characters with dynamic
affective facial expressions. The mechanism is based on Facial Action Coding.
It is easy to implement, and code is available for download. To show the
validity of the expressions generated with the mechanism we tested the
recognition accuracy for 6 basic emotions (joy, anger, sadness, surprise,
disgust, fear) and 4 blend emotions (enthusiastic, furious, frustrated, and
evil). Additionally we investigated the effect of VC distance (z-coordinate),
the effect of the VC's face morphology (male vs. female), the effect of a
lateral versus a frontal presentation of the expression, and the effect of
intensity of the expression. Participants (n=19, Western and Asian subjects)
rated the intensity of each expression for each condition (within subject
setup) in a non forced choice manner. All of the basic emotions were uniquely
perceived as such. Further, the blends and confusion details of basic emotions
are compatible with findings in psychology
Boc-Protection on L-DOPA: an Easy Way to Promote Underwater Adhesion
The ability of mussels to adhere to underwater surfaces has attracted a lot of attention from the scientific community. As proteins containing L-DOPA (3,4-dihydroxyphenyl-l-alanine) are involved in their adhesion, a common strategy to synthesize adhesives is the incorporation of this amino acid into other compounds. Herein, we report a study on four compounds of the family of Bocx-(L-DOPA)n-OMe (x = 1–3; n = 1,2), that we prepared through simple synthetic steps. Three of them showed the capability of underwater adhesion: while they are not adhesive in the dry phase, the adhesiveness is triggered when the dried sample is immersed in water or any aqueous solutions. The introduction of protecting groups stabilizes L-DOPA, preventing the oxidation of the catechol moiety, and enhances the hydrophobicity, helping the removal of water from the surface to bind. These molecules show good adhesiveness, with different properties, so they may be all used as adhesives for different purposes. These outcomes pave the way for new applications for these materials as green and biocompatible adhesives
Optical reconfiguration and polarization control in semi-continuous gold films close to the percolation threshold
Controlling and confining light by exciting plasmons in resonant metallic
nanostructures is an essential aspect of many new emerging optical
technologies. Here we explore the possibility of controllably reconfiguring the
intrinsic optical properties of semi-continuous gold films, by inducing
permanent morphological changes with a femtosecond (fs)-pulsed laser above a
critical power. Optical transmission spectroscopy measurements show a
correlation between the spectra of the morphologically modified films and the
wavelength, polarization, and the intensity of the laser used for alteration.
In order to understand the modifications induced by the laser writing, we
explore the near-field properties of these films with electron energy-loss
spectroscopy (EELS). A comparison between our experimental data and full-wave
simulations on the exact film morphologies hints toward a restructuring of the
intrinsic plasmonic eigenmodes of the metallic film by photothermal effects. We
explain these optical changes with a simple model and demonstrate
experimentally that laser writing can be used to controllably modify the
optical properties of these semi-continuous films. These metal films offer an
easy-to-fabricate and scalable platform for technological applications such as
molecular sensing and ultra-dense data storage.Comment: Supplementary materials available upon request ([email protected]
Accurate rate coefficients for models of interstellar gas-grain chemistry
The methodology for modeling grain-surface chemistry has been greatly
improved by taking into account the grain size and fluctuation effects.
However, the reaction rate coefficients currently used in all practical models
of gas-grain chemistry are inaccurate by a significant amount. We provide
expressions for these crucial rate coefficients that are both accurate and easy
to incorporate into gas-grain models.
We use exact results obtained in earlier work, where the reaction rate
coefficient was defined by a first-passage problem, which was solved using
random walk theory.
The approximate reaction rate coefficient presented here is easy to include
in all models of interstellar gas-grain chemistry. In contrast to the commonly
used expression, the results that it provides are in perfect agreement with
detailed kinetic Monte Carlo simulations. We also show the rate coefficient for
reactions involving multiple species.Comment: 4 pages, 2 figure
Bio-Inspired Aggregation Control of Carbon Nanotubes for Ultra-Strong Composites
High performance nanocomposites require well dispersion and high alignment of
the nanometer-sized components, at a high mass or volume fraction as well.
However, the road towards such composite structure is severely hindered due to
the easy aggregation of these nanometer-sized components. Here we demonstrate a
big step to approach the ideal composite structure for carbon nanotube (CNT)
where all the CNTs were highly packed, aligned, and unaggregated, with the
impregnated polymers acting as interfacial adhesions and mortars to build up
the composite structure. The strategy was based on a bio-inspired aggregation
control to limit the CNT aggregation to be sub 20--50 nm, a dimension
determined by the CNT growth. After being stretched with full structural
relaxation in a multi-step way, the CNT/polymer (bismaleimide) composite
yielded super-high tensile strengths up to 6.27--6.94 GPa, more than 100%
higher than those of carbon fiber/epoxy composites, and toughnesses up to
117--192 MPa. We anticipate that the present study can be generalized for
developing multifunctional and smart nanocomposites where all the surfaces of
nanometer-sized components can take part in shear transfer of mechanical,
thermal, and electrical signals
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