9,275 research outputs found
Front-mediated melting of ultrastable glasses
Ultrastable vapor-deposited glasses display uncommon material properties.
Most remarkably, upon heating they are believed to melt via a liquid front that
originates at the free surface and propagates over a mesoscopic crossover
length, before crossing over to bulk melting. We combine swap Monte Carlo with
molecular dynamics simulations to prepare and melt isotropic amorphous films of
unprecedendtly high kinetic stability. We are able to directly observe both
bulk and front melting, and the crossover between them. We measure the front
velocity over a broad range of conditions, and a crossover length scale that
grows to nearly particle diameters in the regime accessible to
simulations. Our results disentangle the relative roles of kinetic stability
and vapor deposition in the physical properties of stable glasses.Comment: 7 pages, 6 figures; accepted for publication in Phys. Rev. Let
Testing the limits of contextual constraint: interactions with word frequency and parafoveal preview during fluent reading
Contextual constraint is a key factor affecting a word's fixation duration and its likelihood of being fixated during reading. Previous research has generally demonstrated additive effects of predictability and frequency in fixation times. Studies examining the role of parafoveal preview have shown that greater preview benefit is obtained from more predictable and higher frequency words versus less predictable and lower frequency words. In two experiments, we investigated effects of target word predictability, frequency, and parafoveal preview. A 3 (Predictability: low, medium, high) × 2 (Frequency: low, high) design was used with Preview (valid, invalid) manipulated between experiments. With valid previews, we found main effects of Predictability and Frequency in both fixation time and probability measures, including an interaction in early fixation measures. With invalid preview, we again found main effects of Predictability and Frequency in fixation times, but no evidence of an interaction. Fixation probability showed a weak Predictability effect and Predictability-Frequency interaction. Predictability interacted with Preview in early fixation time and probability measures. Our findings suggest that high levels of contextual constraint exert an early influence during lexical processing in reading. Results are discussed in terms of models of language processing and eye movement control
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