Efficient determination of thermodynamic properties from a single simulation

A method for calculating the density of states of a system directly from its trajectory in phase space is described. As a specific example, the method is applied to the Monte Carlo simulation of a two‐dimensional Ising model. The energy distribution function is calculated from the density of states and the associated Helmholtz free energy per spin is calculated for various system sizes and temperatures and shown to be in excellent agreement with the exact results.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69798/2/JCPSA6-99-10-7993-1.pd

Effects of spatial dimensionality and steric interactions on microtubule-motor self-organization

Active networks composed of filaments and motor proteins can self-organize into a variety of architectures. Computer simulations in two or three spatial dimensions and including or omitting steric interactions between filaments can be used to model active networks. Here we examine how these modelling choices affect the state space of network self-organization. We compare the networks generated by different models of a system of dynamic microtubules and microtubule-crosslinking motors. We find that a thin 3D model that includes steric interactions between filaments is the most versatile, capturing a variety of network states observed in recent experiments. In contrast, 2D models either with or without steric interactions which prohibit microtubule crossings can produce some, but not all, observed network states. Our results provide guidelines for the most appropriate choice of model for the study of different network types and elucidate mechanisms of active network organization

Multilayer film stability

We apply a linear stability analysis to examine the effect of misfit stress on the interface diffusion controlled morphological stability of multilayer microstructures. The stresses could be the result of misfit strains between the individual film layers and/or between film and substrate. We find that misfit between the layers in the film can destabilize the multilayer structure in cases where the thinner layer is elastically stiffer than the thicker layer. The rate at which these instabilities develop increase with increasing misfit and decreasing interfacial energy. Even when there is no misfit between layers, the misfit between the multilayer film and substrate can destabilize the interfaces. This type of instability occurs whether the thinner layers are stiffer or more compliant than the thicker ones. By appropriate choice of the elastic moduli mismatch between layers and relative layer thicknesses, the presence of an interlayer misfit can suppress the instability caused by the substrate misfit. We present stability diagrams that can be used to design stable, multilayer films using all of the degrees of freedom commonly available in multilayer film deposition. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71112/2/JAPIAU-82-10-4852-1.pd

Manufacturing High-Fidelity Lunar Agglutinate Simulants

The lunar regolith is very different from many naturally occurring material on Earth because it forms in the unique, impact-dominated environment of the lunar surface. Lunar regolith is composed of five basic particle types: mineral fragments, pristine crystalline rock fragments, breccia fragments, glasses of various kinds, and agglutinates (glass-bonded aggregates). Agglutinates are abundant in the lunar regolith, especially in mature regoliths where they can be the dominant component.This presentation will discuss the technical feasibility of manufacturing-simulated agglutinate particles that match many of the unique properties of lunar agglutinates

An evaluation of the implementation of Georgia's Pre-k program: Report of the findings from the Georgia Early Childhood Study (2002-03)

After ten years, Georgia continues to lead the nation in providing full day, publicly subsidized Pre-K to four-year-olds whose parents choose to enroll them. In this report, we assess the extent to which differences in the way Pre-K is implemented affect children's development. Do teachers with higher levels of education have more positive impacts on children's development? Do teaching styles make a difference in terms of children's outcomes by the end of kindergarten? Do children taught using certain curricula fare better than those taught using others? Answers to questions such as these can assist Pre-K administrators in refining Georgia's program and inform those in other states who are developing or expanding their prekindergarten programs

Investment suitability and path dependency perpetuate inequity in international mitigation finance toward developing countries

Developed country pledges to provide finance to developing countries for their mitigation actions sit at the heart of international climate cooperation. Currently, climate finance largely flows to big and fast-growing developing countries while low-income and vulnerable countries are underserved. Here, using wind and solar project data, we highlight inequities in the distribution of international investments in mitigation across developing countries and explore the factors that influence public and private investment flows. Results show that public actors are influenced by domestic climate policies since the Paris Agreement, while private finance flows are shaped by investment suitability conditions, which restricts access to both types of finance in the poorest countries. Further, public and private flows are strongly shaped by path dependency, generating an “investment lock-in” that perpetuates distributional inequities. Future international commitments to direct climate finance should address distributional issues to meet countries’ needs and the goals of the Paris Agreement