Configurational Temperature in Membrane Simulations Using Dissipative Particle Dynamics

The use of excessively long timesteps in dissipative particle dynamics simulations may produce simulation artifacts due to the generation of configurations which are not representative of the desired canonical ensemble. The configurational temperature, amongst other quantities, may be used to assess the extent of the deviation from equilibrium. This paper presents results for simulations of models of water, and lipid bilayer membranes, to illustrate the nature of the problems.Comment: 13 pages, 7 figures, RevTex

Spin dynamics for the Lebwohl-Lasher model

A spin dynamics algorithm, combining checkerboard updating and a rotation algorithm based on the local second-rank ordering field, is developed for the Lebwohl-Lasher model of liquid crystals. The method is shown to conserve energy well and to generate simulation averages that are consistent with those obtained by Monte Carlo simulation. However, care must be taken to avoid the undesirable effects of director rotation, and a method for doing this is proposed

Molecular simulations of entangled defect structures around nanoparticles in nematic liquid crystals

We investigate the defect structures forming around two nanoparticles in a Gay-Berne nematic liquid crystal using molecular simulations. For small separations, disclinations entangle both particles forming the figure of eight, the figure of omega and the figure of theta. These defect structures are similar in shape and occur with a comparable frequency to micron-sized particles studied in experiments. The simulations reveal fast transitions from one defect structure to another suggesting that particles of nanometre size cannot be bound together effectively. We identify the 'three-ring' structure observed in previous molecular simulations as a superposition of the different entangled and non-entangled states over time and conclude that it is not itself a stable defect structure.Comment: keywords: molecular-simulation, defects, nematic, disclination, algorithmic classification ; 8 pages, 7 figures, 1 tabl

Folding kinetics of a polymer [corrigendum]

In our original article (Phys. Chem. Chem. Phys., 2012, 14, 60446053) a convergence problem resulted in an averaging error in computing the entropy from a set of Wang-Landau Monte-Carlo simulations. Here we report corrected results for the freezing temperature of the homopolymer chain as a function of the range of the non-bonded interaction. We find that the previously reported forward-flux sampling (FFS) and brute-force (BF) simulation results are in agreement with the revised Wang-Landau (WL) calculations. This confirms the utility of FFS for computing crystallisation rates in systems of this kind.Comment: 2 pages, 4 figure

The Constitution at the Threshold of Life and Death: A Suggested Approach to Accommodate an Interest in Life and a Right to Die

In the past fifteen years, the United States Supreme Court has decided three cases in which it tentatively began to explore what the United States Constitution has to say about issues that are popularly described as the right to die. In this article, I suggest that the current state of constitutional analysis does not provide for an effective mechanism for securing an individual\u27s right to die, at least not without undervaluing a state\u27s interest in the preservation of human life should a state choose to take such a position. In the article, I suggest that it is possible to adopt a means of balancing the competing interests of the individual and of the state in such a way as to do service to both of them. I propose that the Court adopt a balancing standard modeled generally on, but by no means identical to, the current constitutional mechanism under which infringements on a woman\u27s right to have an abortion during the period prior to fetal viability are judged. In other words, I propose the adoption of an undue bruden standard similar to that articulated in Casey. In the article I explain why the current state of affairs is deficient. Thereafter, I explore the undue burden standard I propose, explaining how it would address the deficiencies in current law as well as cure many of the problems identified with the Casey standard itself. Finally, I apply the standard to several scenarios. I ultimately conclude that adopting the standard I propose is justified despite the risks associated with it. I also conclude, however, that those risks do not warrant the maintenance of the standard in other areas, including with respect to abortion

A Limited Defense of (at Least Some of) the Umpire Analogy

This Essay provides at least a limited defense of some parts of the umpire analogy and ultimately suggests that this analogy may tell us something important about the more general role of courts in the United States. This Essay proceeds in four parts. Part II explores in more depth what those making the umpire analogy appear to mean. At its heart, the analogy principally has been used to address the substantive decision making of judges. This Part will explain that there is more to the analogy than such a narrow decisional focus suggests. Part III builds on Part II. It explains non-decision making similarities between umpires and judges. This Part suggests that the analogy is more complex than is apparent if one only views it through the lens of decision making. It also explores how these non-decisional similarities can be useful in understanding the role of the judiciary in our constitutional system. Part IV of the Essay turns to the analogy as applied to decision making specifically. It is here that the debate has raged. Part IV argues that the analogy provides some important insight into the decisional role of judges. Part V returns to the broader theme of this symposium. It explains how the umpire analogy informs a consideration of the appropriate role of a judge in American constitutional democracy. It acknowledges the dangers inherent in the use of this particular analogy, but ultimately concludes that the risks are worth taking

A Limited Defense of (at Least Some of) the Umpire Analogy

This Essay provides at least a limited defense of some parts of the umpire analogy and ultimately suggests that this analogy may tell us something important about the more general role of courts in the United States. This Essay proceeds in four parts. Part II explores in more depth what those making the umpire analogy appear to mean. At its heart, the analogy principally has been used to address the substantive decision making of judges. This Part will explain that there is more to the analogy than such a narrow decisional focus suggests. Part III builds on Part II. It explains non-decision making similarities between umpires and judges. This Part suggests that the analogy is more complex than is apparent if one only views it through the lens of decision making. It also explores how these non-decisional similarities can be useful in understanding the role of the judiciary in our constitutional system. Part IV of the Essay turns to the analogy as applied to decision making specifically. It is here that the debate has raged. Part IV argues that the analogy provides some important insight into the decisional role of judges. Part V returns to the broader theme of this symposium. It explains how the umpire analogy informs a consideration of the appropriate role of a judge in American constitutional democracy. It acknowledges the dangers inherent in the use of this particular analogy, but ultimately concludes that the risks are worth taking