Liquid-vapour asymmetry in pure fluids: A Monte Carlo simulation study

Monte Carlo simulations within the grand canonical ensemble are used to obtain the joint distribution of density and energy fluctuations $p_L(\rho,u)$ for two model fluids: a decorated lattice gas and a polymer system. In the near critical region the form of $p_L(\rho,u)$ is analysed using a mixed field finite-size-scaling theory that takes account of liquid-vapour asymmetry. Field mixing transformations are performed that map $p_L(\rho,u)$ onto the joint distribution of critical scaling operators \ptMEstar\ appropriate to the Ising fixed point. Carrying out this procedure permits a very accurate determination of the critical point parameters. By forming various projections of \ptMEstar , the full universal finite-size spectrum of the critical density and energy distributions of fluids is also obtained. In the sub-critical coexistence region, an examination is made of the influence of field mixing on the asymmetry of the density distribution.Comment: 19 pages Latex, 15 Figures available on request. Report Number #IP-94.15

Accurate Measurements of the Chemical Potential of Polymeric Systems by Monte-Carlo Simulation

We present a new Monte-Carlo method for estimating the chemical potential of model polymer systems. The method is based upon the gradual insertion of a penetrable `ghost' polymer into the system and is effective for large chain lengths and at high densities. Insertion of the ghost chain is facilitated by use of an expanded ensemble in which weighted transitions are permitted between states characterising the strength of the excluded volume and thermal interactions experienced by the ghost chain. We discuss the implementation and optimisation of the method within the framework of the bond fluctuation model, and demonstrate its precision by a calculation of the finite-size corrections to the chemical potential.Comment: 12 pages Latex, Report Number #IP-94.12

Anomalous size-dependence of interfacial profiles between coexisting phases of polymer mixtures in thin film geometry: A Monte-Carlo simulation

The interfacial profile between coexisting phases of a binary mixture (A,B) in a thin film of thickness D and lateral linear dimensions L depends sensitively on both linear dimensions and on the nature of boundary conditions and statistical ensembles applied. These phenomena generic for systems in confined geometry are demonstrated by Monte-Carlo simulations of the bond fluctuation model of symmetric polymer mixtures. Both the canonical and semi-grand-canonical ensemble are studied. In the canonical ensemble, the interfacial width w increases (from small values which are of the same order as the intrinsic profile) like sqrt{D}, before a crossover to a saturation value w_max (w_max^2 proportional to ln L) sets in. In the semi-grand-canonical ensemble, however, one finds the same widths (w proportional to sqrt{D}) as in the canonical ensemble for not too large L, while for large L the interfacial profile is smeared out over a finite fraction of the film thickness (w proportional to D for D -> infinity). We discuss the implications of these findings for the interpretation of both simulations and experiments.Comment: 42 pages, including 15 PS figures, to appear in JC

Gender Differences in the Impact of Worklife on Executives’ Psychological Health

The Impact of Worklife on Executives’ Psychological Health Purpose: This is the first scientific research studying the impact of worklife factors on executives’ psychological health by gender. The study has a particular focus on the factors of ‘Community’ and ‘Work-life balance’. Design: Survey data were collected from N=481 senior executives to measure seven worklife factors and psychological health. Standardized regression analysis was performed for each worklife in a regression model predicting psychological health by gender. Findings: Results showed significant differences between female and male senior executives in the profiles of seven worklife factors in terms of their relationship with psychological health. ‘Work-life balance’ was the strongest predictor of female executives’ psychological health, ‘Values’ for male executives’ psychological health. ‘Community’ showed similar levels of association for both women and men. Originality/value: This research addresses the literature gap of large-scale, quantitative investigations into the psychology of senior executives. The results can be applied as a guide for organizational design, executive training and development programs accounting for differences by gender

Political Institutions, Policymaking Processes and Policy Outcomes in Brazil

We found that the driving force behind policies in Brazil is the strong set of powers given to the President by the Constitution of 1988. To have strong powers does not mean unbridled powers. Several institutions constrain and check the power of the President, in particular the legislature, the judiciary, the public prosecutors, the auditing office, state governors and the Constitution itself. The electorate of Brazil holds the President accountable for economic growth, inflation and unemployment. Because of the electoral connection, and perhaps reputational effects, presidents in Brazil have a strong incentive to pursue stable fiscal and monetary policies as their first priority. At least for the past ten years, and particularly in the new administration of Lula, executive power has been aimed at pushing policy towards macro orthodoxy. Although orthodoxy may not lead to short-term growth, international financial markets provide additional incentives for discipline, as deviations are instantly punished, with unfavorable consequences that are readily recognized by the electorate. Achieving stable macro policies required constitutional amendments as well as considerable legislation. To attain their goals, the past administrations (Cardoso and Lula in particular) used their property rights over pork to trade for policy changes. The rationale for members of Congress to exchange votes on policy for pork is that the electorates reward or punish members of Congress based on the degree to which pork lands in their district. With the exception of the devaluation of 1999, macro policy has become more stable over time. We categorize macro policies in Brazil as `stable but adaptable. `

A Survey of the Application of Machine Learning in Decision Support Systems

Machine learning is a useful technology for decision support systems and assumes greater importance in research and practice. Whilst much of the work focuses technical implementations and the adaption of machine learning algorithms to application domains, the factors of machine learning design affecting the usefulness of decision support are still understudied. To enhance the understanding of machine learning and its use in decision support systems, we report the results of our content analysis of design-oriented research published between 1994 and 2013 in major Information Systems outlets. The findings suggest that the usefulness of machine learning for supporting decision-makers is dependent on the task, the phase of decision-making, and the applied technologies. We also report about the advantages and limitations of prior research, the applied evaluation methods and implications for future decision support research. Our findings suggest that future decision support research should shed more light on organizational and people-related evaluation criteria