Wall-mediated self-diffusion in slit and cylindrical pores

Analytical and numerical simulation studies are performed on the diffusion of simple fluids in both thin slits and long cylindrical pores. In the region of large Knudsen numbers, where the wall-particle collisions outnumber the intermolecular collisions, we obtain analytical results for the self-diffusion coefficients for both slit and cylindrical pore shapes. The results show anomalous behavior of the mean square displacement and the velocity autocorrelation for the case of slits, unlike the case of cylindrical pores which shows standard Fick's law. Molecular dynamics simulations confirm the analytical results. We further study the wall-mediated diffusion behavior conducted by a Smoluchowski thermal wall and compare with our analytical results obtained from the stochastic thermal wall model proposed by Mon and Percus

50 Years of the Golomb--Welch Conjecture

Since 1968, when the Golomb--Welch conjecture was raised, it has become the main motive power behind the progress in the area of the perfect Lee codes. Although there is a vast literature on the topic and it is widely believed to be true, this conjecture is far from being solved. In this paper, we provide a survey of papers on the Golomb--Welch conjecture. Further, new results on Golomb--Welch conjecture dealing with perfect Lee codes of large radii are presented. Algebraic ways of tackling the conjecture in the future are discussed as well. Finally, a brief survey of research inspired by the conjecture is given.Comment: 28 pages, 2 figure

How has welfare to work reform affected the mental health of single parents in Australia?

Concerns raised about the inadequacy of income support payments in Australia have chiefly centred on the increased poverty experienced by highly vulnerable recipients, such as single parents. This poverty not only increases the risk of social exclusion, but has broader implications for health and wellbeing.This research was funded through a grant - ARC Grant #DP120101887

Strategic Positioning and the Financing of Nonprofit Organizations: Is Efficiency Rewarded in the Contributions Marketplace?

This article addresses the question of whether operational efficiency is recognized and rewarded by the private funders that support nonprofit organizations in fields ranging from education to social service to arts and beyond. Looking at the administrative efficiency and fundraising results of a large sample of nonprofit organizations over an 11 year period, we find that nonprofits that position themselves as cost efficient reporting low administrative to total expense ratios fared no better over time than less efficient appearing organizations in the market for individuals, foundations, and corporate contributions. From this analysis, we suggest that economizing may not always be the best strategy in the nonprofit sector. This publication is Hauser Center Working Paper No. 2. The Hauser Center Working Paper Series was launched during the summer of 2000. The Series enables the Hauser Center to share with a broad audience important works-in-progress written by Hauser Center scholars and researchers

On the Accuracy of Bootstrap Confidence Intervals for Efficiency Levels in Stochastic Frontier Models with Panel Data

We study the construction of confidence intervals for efficiency levels of individual firms in stochastic frontier models with panel data. The focus is on bootstrapping and related methods. We start with a survey of various versions of the bootstrap. We also propose a simple parametric alternative in which one acts as if the identity of the best firm is known. Monte Carlo simulations indicate that the parametric method works better than the per- centile bootstrap, but not as well as bootstrap methods that make bias corrections. All of these methods are valid only for large time-series sample size (T), and correspondingly none of the methods yields very accurate confidence intervals except when T is large enough that the identity of the best firm is clear. We also present empirical results for two well-known data sets.Stochastic frontier, bootstrap, efficiency

The Art & Science of Creating Effective Youth Programs

"The Art & Science of Creating Effective Youth Programs" utilizes findings from a national collective impact study conducted by Algorhythm through their Youth Development Impact Learning System (YDiLS), which surveyed 27 organizations, 80 programs and more than 3,000 youth. The YDiLS is an online evaluation tool through which youth complete pre and post surveys that measure the growth in six, research-based "Social and Emotional Learning" (SEL) capacities proven to be foundational to long-term success in life:1. Academic Self-Efficacy 2. Contribution 3. Positive Identity 4. Self-Management 5. Social Capital 6. Social Skill

Comparison of free energy estimators and their dependence on dissipated work

The estimate of free energy changes based on Bennett's acceptance ratio method is examined in several limiting cases and compared with other estimates based on the Jarzynski equality and on the Crooks relation. While the absolute amount of dissipated work, defined as the surplus of average work over the free energy difference, limits the practical applicability of Jarzynski's and Crooks' methods, the reliability of Bennett's approach is restricted by the difference of the dissipated works in the forward and the backward process. We illustrate these points by considering a Gaussian chain and a hairpin chain which both are extended during the forward and accordingly compressed during the backward protocol. The reliability of the Crooks relation predominantly depends on the sample size; for the Jarzynski estimator the slowness of the work protocol is crucial, and the Bennett method is shown to give precise estimates irrespective of the pulling speed and sample size as long as the dissipated works are the same for the forward and the backward process as it is the case for Gaussian work distributions. With an increasing dissipated work difference the Bennett estimator also acquires a bias which increases roughly in proportion to this difference. A substantial simplification of the Bennett estimator is provided by the 1/2-formula which expresses the free energy difference by the algebraic average of the Jarzynski estimates for the forward and the backward processes. It agrees with the Bennett estimate in all cases when the Jarzynski and the Crooks estimates fail to give reliable results