Registered and antiregistered phase separation of mixed amphiphilic bilayers

We derive a mean-field free energy for the phase behaviour of coupled bilayer leaflets, which is implicated in cellular processes and important to the design of artificial membranes. Our model accounts for amphiphile-level structural features, particularly hydrophobic mismatch, which promotes antiregistration (AR), in competition with the `direct' trans-midplane coupling usually studied, promoting registration (R). We show that the phase diagram of coupled leaflets allows multiple \textit{metastable} coexistences, then illustrate the kinetic implications with a detailed study of a bilayer of equimolar overall composition. For approximate parameters estimated to apply to phospholipids, equilibrium coexistence is typically registered, but metastable antiregistered phases can be kinetically favoured by hydrophobic mismatch. Thus a bilayer in the spinodal region can require nucleation to equilibrate, in a novel manifestation of Ostwald's `rule of stages'. Our results provide a framework for understanding disparate existing observations, elucidating a subtle competition of couplings, and a key role for phase transition kinetics in bilayer phase behaviour.Comment: Final authors' version. Important typo in Eq. A24 corrected. To appear in Biophysical Journa

The corporate social performance of developing country multinationals

In this paper, we explore the Corporate Social Performance (CSP) of Developing Country Multinationals (DMNCs). We argue that in competing internationally, DMNCs often face both reputation and legitimacy deficits, which they address by improving their CSP. We develop a series of hypotheses to explain the variation in CSP between DMNCs and domestic-only firms from developing countries and also examine variations in CSP between DMNCs depending on the extent of their multinationality and portfolio of host countries. Our findings support all our hypotheses, which suggest that DMNCs display enhanced levels of CSP compared to their domestic-only counterparts. CSP is also found to be positively related to the DMNCs’ degree of multinationality, but with a declining incremental impact, whereas entry into developed markets leads to a greater improvement in DMNCs’ CSP than expansion into developing markets. We highlight the implications of our findings for managers and researchers

Simplification and generalization of large scale data for roads : a comparison of two filtering algorithms

This paper reports the results of an in-depth study which investigated two algorithms for line simplification and caricatural generalization (namely, those developed by Douglas and Peucker, and Visvalingam, respectively) in the context of a wider program of research on scale-free mapping. The use of large-scale data for man-designed objects, such as roads, has led to a better understanding of the properties of these algorithms and of their value within the spectrum of scale-free mapping. The Douglas-Peucker algorithm is better at minimal simplification. The large-scale data for roads makes it apparent that Visvalingam's technique is not only capable of removing entire scale-related features, but that it does so in a manner which preserves the shape of retained features. This technique offers some prospects for the construction of scale-free databases since it offers some scope for achieving balanced generalizations of an entire map, consisting of several complex lines. The results also suggest that it may be easier to formulate concepts and strategies for automatic segmentation of in-line features using large-scale road data and Visvalingam's algorithm. In addition, the abstraction of center lines may be facilitated by the inclusion of additional filtering rules with Visvalingam's algorithm

Generalising roads on large-scale maps : a comparison of two algorithms

CISRG discussion paper ; 1

Measuring Ancient Inequality

Is inequality largely the result of the Industrial Revolution? Or, were pre-industrial incomes and life expectancies as unequal as they are today? For want of sufficient data, these questions have not yet been answered. This paper infers inequality for 14 ancient, pre-industrial societies using what are known as social tables, stretching from the Roman Empire 14 AD, to Byzantium in 1000, to England in 1688, to Nueva España around 1790, to China in 1880 and to British India in 1947. It applies two new concepts in making those assessments – what we call the inequality possibility frontier and the inequality extraction ratio. Rather than simply offering measures of actual inequality, we compare the latter with the maximum feasible inequality (or surplus) that could have been extracted by the elite. The results, especially when compared with modern poor countries, give new insights in to the connection between inequality and economic development in the very long run.Inequality possibility frontier; pre-industrial inequality; history