4,467 research outputs found
Modifying Fragility and Collective Motion in Polymer Melts with Nanoparticles
We investigate the impact of nanoparticles (NP) on the fragility and
cooperative string-like motion in a model glass-forming polymer melt by
molecular dynamics simulation. The NP cause significant changes to both the
fragility and the average length of string-like motion, where the effect
depends on the NP-polymer interaction and the NP concentration. We interpret
these changes via the Adam-Gibbs (AG) theory, assuming the strings can be
identified with the "cooperatively rearranging regions" of AG. Our findings
indicate fragility is primarily a measure of the temperature dependence of the
cooperativity of molecular motion.Comment: To appear in Physical Review Letter
The Inconceivable Popularity of Conceivability Arguments
Famous examples of conceivability arguments include (i) Descartes’ argument for mind-body dualism, (ii) Kripke's ‘modal argument’ against psychophysical identity theory, (iii) Chalmers’ ‘zombie argument’ against materialism, and (iv) modal versions of the ontological argument for theism. In this paper, we show that for any such conceivability argument, C, there is a corresponding ‘mirror argument’, M. M is deductively valid and has a conclusion that contradicts C's conclusion. Hence, a proponent of C—henceforth, a ‘conceivabilist’—can be warranted in holding that C's premises are conjointly true only if she can find fault with one of M's premises. But M's premises are modelled on a pair of C's premises. The same reasoning that supports the latter supports the former. For this reason, a conceivabilist can repudiate M's premises only on pain of severely undermining C's premises. We conclude on this basis that all conceivability arguments, including each of (i)–(iv), are fallacious
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