Pressure-energy correlations and thermodynamic scaling in viscous Lennard-Jones liquids

We use molecular dynamics simulation results on viscous binary Lennard-Jones mixtures to examine the correlation between the potential energy and the virial. In accord with a recent proposal [U. R. Pedersen et. al. Phys. Rev. Lett. 100, 015701 (2008)], the fluctuations in the two quantities are found to be strongly correlated, exhibiting a proportionality constant, Gamma, numerically equal to one-third the slope of an inverse power law approximation to the intermolecular potential function. The correlation is stronger at higher densities, where interatomic separations are in the range where the inverse power law approximation is more accurate. These same liquids conform to thermodynamic scaling of their dynamics, with the scaling exponent equal to Gamma. Thus, the properties of strong correlation between energy and pressure and thermodynamic scaling both reflect the ability of an inverse power law representation of the potential to capture interesting features of the dynamics of dense, highly viscous liquids.Comment: 5 pages, 4 figures; published version, one figure remove

Events, processes, and the time of a killing

The paper proposes a novel solution to the problem of the time of a killing (ToK), which persistently besets theories of act-individuation. The solution proposed claims to expose a crucial wrong-headed assumption in the debate, according to which ToK is essentially a problem of locating some event that corresponds to the killing. The alternative proposal put forward here turns on recognizing a separate category of dynamic occurents, viz. processes. The paper does not aim to mount a comprehensive defense of process ontology, relying instead on extant defenses. The primary aim is rather to put process ontology to work in diagnosing the current state of play over ToK, and indeed in solving it

Elementos y esencias

La autora compara los modos en que Aristóteles, los filósofos materialistas antiguos y la ciencia natural moderna explican el término “elemento”. El interés filosófico de este análisis depende del dictum wittgensteiniano: “La esencia es expresada por la gramática”. En la discusión sobre Aristóteles se examinan las nociones de materia prima, forma y sustancia. Se concluye que el uso de los términos técnicos por ciertos grupos humanos —como el de los científicos naturales— produce una “especie-de-esencias” no eternas ni inmutables.The author compares the ways in which the term “element” has been explicated by Aristotle, ancient materialists, and modern natural science. The philosophical interest of this analysis stems from Wittgenstein’s dictum: “essence is expressed by grammar.” In the context of Aristotle’s thought, the ideas of first matter, form, and substance are examined. The conclusion is that the use of technical terms by certain communities—such as natural scientists— produces a “species-of-essences” neither eternal nor immutable

Proprietary Reasons and Joint Action

Some of the reasons one acts on in joint action are shared with fellow participants. But others are proprietary: reasons of one’s own that have no direct practical significance for other participants. The compatibility of joint action with proprietary reasons serves to distinguish the former from other forms of collective agency; moreover, it is arguably a desirable feature of joint action. Advocates of “team reasoning” link the special collective intention individual participants have when acting together with a distinctive form of practical reasoning that purports to put individuals in touch with group or collective reasons. Such views entail the surprising conclusion that one cannot engage in joint action for proprietary reasons. Suppose we understand the contrast between minimal and robust forms of joint action in terms of the extent to which participants act on proprietary reasons as opposed to shared reasons. Then, if the team reasoning view of joint intention and action is correct, it makes no sense to talk of minimal joint action. As soon as the reason for which one participates is proprietary, then one is not, on this view, genuinely engaged in joint action

Handover - Enabling Learning in Communication for Safety (HELiCS): a report on achievements at two hospital sites

The provision of health care is becoming increasingly complex and fragmented.1,2 As a result, to ensure continuity of care, the handover of clinical tasks is becoming more frequent and important. However, the general lack of clinical handover planning and training in handover communication creates unacceptable risks for patients.1 Not surprisingly, clinical handover has been identified as a major international policy and research priority