A square-well model for the structural and thermodynamic properties of simple colloidal systems

A model for the radial distribution function $g(r)$ of a square-well fluid of variable width previously proposed [S. B. Yuste and A. Santos, J. Chem. Phys. {\bf 101}, 2355 (1994)] is revisited and simplified. The model provides an explicit expression for the Laplace transform of $rg(r)$, the coefficients being given as explicit functions of the density, the temperature, and the interaction range. In the limits corresponding to hard spheres and sticky hard spheres the model reduces to the analytical solutions of the Percus-Yevick equation for those potentials. The results can be useful to describe in a fully analytical way the structural and thermodynamic behavior of colloidal suspensions modeled as hard-core particles with a short-range attraction. Comparison with computer simulation data shows a general good agreement, even for relatively wide wells.Comment: 23 pages, 10 figures; Figs. 4 and 5 changed, Fig. 6 new; to be published in J. Chem. Phy

Biological Individuals

The impressive variation amongst biological individuals generates many complexities in addressing the simple-sounding question what is a biological individual? A distinction between evolutionary and physiological individuals is useful in thinking about biological individuals, as is attention to the kinds of groups, such as superorganisms and species, that have sometimes been thought of as biological individuals. More fully understanding the conceptual space that biological individuals occupy also involves considering a range of other concepts, such as life, reproduction, and agency. There has been a focus in some recent discussions by both philosophers and biologists on how evolutionary individuals are created and regulated, as well as continuing work on the evolution of individuality

Soft sphere model for electron correlation and scattering in the atomistic modelling of semiconductor devices

The atomistic modelling of silicon MOSFET devices becomes essential at deep sub-micron scales when it is no longer possible to represent the charged impurities by a continuous charge distribution with a determined doping density. Instead the spatial distribution and the actual number of dopants must be treated as discrete random variables. The present paper addresses the issue of modelling the dynamics of discrete carrier flow in a semiconductor device utilising a simple model of the carrier-carrier scattering and carrier-fixed impurity scattering which is suitable for efficient simulations of large ensembles of devices

Efficient hole transport model in warped bands for use in the simulation of Si/SiGe MOSFETs

An analytical geometric model for the valence band in strained and relaxed Si1-xGex is presented, which shows good agreement with a 6-band k·p analysis of the valence band. The geometric model allows us to define an effective mass tensor for the warped valence band structure. The model also has applications in the study of III-V semiconductors, and could aid in the interpretation of cyclotron resonance experiments in these bands. A warped three-band Monte Carlo simulation has been developed based on this model making use of the efficient calculation of trajectory dynamics that is made possible through the use of such a model. The calculated transport characteristics show good agreement with the available experimental data

Methods Matter: Beating the Backward Clock

In “Beat the (Backward) Clock,” we argued that John Williams and Neil Sinhababu’s Backward Clock Case fails to be a counterexample to Robert Nozick’s or Fred Dretske’s Theories of Knowledge. Williams’ reply to our paper, “There’s Nothing to Beat a Backward Clock: A Rejoinder to Adams, Barker and Clarke,” is a further attempt to defend their counterexample against a range of objections. In this paper, we argue that, despite the number and length of footnotes, Williams is still wrong