Critical phase behavior in multi-component fluid mixtures: Complete scaling analysis

We analyze the critical gas-liquid phase behavior of arbitrary fluid mixtures in their coexistence region. We focus on the setting relevant for polydisperse colloids, where the overall density and composition of the system are being controlled, in addition to temperature. Our analysis uses the complete scaling formalism and thus includes pressure mixing effects in the mapping from thermodynamic fields to the effective fields of 3D Ising criticality. Because of fractionation, where mixture components are distributed unevenly across coexisting phases, the critical behavior is remarkably rich. We give scaling laws for a number of important loci in the phase diagram. These include the cloud and shadow curves, which characterise the onset of phase coexistence, a more general set of curves defined by fixing the fractional volumes of the coexisting phases to arbitrary values, and conventional coexistence curves of the densities of coexisting phases for fixed overall density. We identify suitable observables (distinct from the Yang-Yang anomalies discussed in the literature) for detecting pressure mixing effects. Our analytical predictions are checked against numerics using a set of mapping parameters fitted to simulation data for a polydisperse Lennard-Jones fluid, allowing us to highlight crossovers where pressure mixing becomes relevant close to the critical point.Comment: 21 pages, 7 captioned figure

Phase separation dynamics of polydisperse colloids: a mean-field lattice-gas theory

New insights into phase separation in colloidal suspensions are provided via a new dynamical theory based on the Polydisperse Lattice-Gas model. The model gives a simplified description of polydisperse colloids, incorporating a hard-core repulsion combined with polydispersity in the strength of the attraction between neighbouring particles. Our mean-field equations describe the local concentration evolution for each of an arbitrary number of species, and for an arbitrary overall composition of the system. We focus on the predictions for the dynamics of colloidal gas-liquid phase separation after a quench into the coexistence region. The critical point and the relevant spinodal curves are determined analytically, with the latter depending only on three moments of the overall composition. The results for the early-time spinodal dynamics show qualitative changes as one crosses a 'quenched' spinodal that excludes fractionation and so allows only density fluctuations at fixed composition. This effect occurs for dense systems, in agreement with a conjecture by Warren that, at high density, fractionation should be generically slow because it requires inter-diffusion of particles. We verify this conclusion by showing that the observed qualitative changes disappear when direct particle-particle swaps are allowed in the dynamics. Finally, the rich behaviour beyond the spinodal regime is examined, where we find that the evaporation of gas bubbles with strongly fractionated interfaces causes long-lived composition heterogeneities in the liquid phase; we introduce a two-dimensional density histogram method that allows such effects to be easily visualized for an arbitrary number of particle species.Comment: 20 pages; accepted for publication in Physical Chemistry Chemical Physic

On the sustainability of the Spanish public budget performance

In this paper, we address the issue of whether the current fiscal policy in Spain is sustainable. For this purpose we apply traditional empirical tests of fiscal sustainability proposed in the literature and, in addition, we introduce a deeper univariate analysis of the series involved. Our results show that a structural break seems to have taken place gradually in the Spanish budget performance, allowing to verifying the intertemporal borrowing constraint in a «strong sense», which means that no problems in marketing public debt are expected to arise if fiscal variables follow the pattern of the past in the future. Classification-JEL : E60, F41,: Sustainability, cointegration, structural breaks, intertemporal borrowing constraint.

Repository profile: University of Glasgow: "Enlighten" IR & Research System

The University of Glasgow has established the “Enlighten” IR and Research system. The IR holds 72,000 items for institutional peer-reviewed journal articles, published conference papers, books and book chapters.<p></p> The Research System is an in-house-built system holding research information for institutional research activity, including people, organisations, projects and outputs. It is dynamically linked to the Enlighten IR.<p></p&gt

The economic effects of exogenous fiscal shocks in Spain: a SVAR approach

This paper estimates the effects of exogenous fiscal policy shocks in Spain in a VAR framework. Government expenditure expansionary shocks are found to have positive effects on output in the short-term at the cost of higher inflation and public deficits and lower output in the medium and long term. Tax increases are found to drag economic activity in the medium term while entailing an only temporary improvement of the public budget balance. The application of these results to the analysis of fiscal policy in Spain since the mid-nineties points to the conclusion that the consolidation process does not seem to have involved costs in terms of output growth. Moreover, the stance of fiscal policy has become more counter-cyclical in that period. JEL Classification: E62, H30Fiscal multipliers, Fiscal shocks, VAR

New research support roles for university libraries

The presentation summarises the new roles in the area of research information management that research libraries worldwide are gradually adopting. A brief description of the current CRIS landscape worldwide and in Latin America is provided, together with 'snapshots' taken from the euroCRIS Directory of Research Information Systems (DRIS) showing how distributed open source CRIS systems like DSpace-CRIS and VIVO are across the world. An update on a recent workline is finally delivered, namely the test harvesting and aggregation of CRIS metadata feeds by OpenAIRE

Current Research Information Systems (CRIS) as OpenAIRE Data Providers

The presentation summarises the current status of the process for adding CRIS systems to the range of certified OpenAIRE data providers via the implementation of the CERIF-XML Guidelines for CRIS Managers v1.1.1. The case is made for the exposure of the CRIS metadata feed to OpenAIRE regardless of whether the associated institutional repository is already OpenAIRE-compliant. It is argued that the contextual metadata provided by CRIS systems may prove invaluable as a complement to the outputs delivered by literature and data repositories as we move towards a subject-based implementation of Open Scienc