From the double-stranded helix to the chiral nematic phase of B-DNA: a molecular model

B-DNA solutions of suitable concentration form left-handed chiral nematic phases (cholesterics). Such phases have also been observed in solutions of other stiff or semiflexible chiral polymers; magnitude and handedness of the cholesteric pitch are uniquely related to the molecular features. In this work we present a theoretical method and a numerical procedure which, starting from the structure of polyelectrolytes, lead to the prediction of the cholesteric pitch. Molecular expressions for the free energy of the system are obtained on the basis of steric and electrostatic interactions between polymers; the former are described in terms of excluded volume, while a mean field approximation is used for the latter. Calculations have been performed for 130 bp fragments of B-DNA. The theoretical predictions provide an explanation for the experimental behavior, by showing the counteracting role played by shape and charge chirality of the molecule.Comment: 42 pages, 6 figure

Debt Dynamics and Contingency Financing: Theoretical Reappraisal of the HIPC Initiative

Sovereign debt management, External debt, Foreign aid, Growth models, Economic development

Assessing the Aid Allocation and Debt Sustainability Framework: Working Towards Incentive Compatible Aid Contracts

This paper criticizes the current International Development Association (IDA) aid allocation and debt sustainability framework on the grounds of their over-reliance on the country policy and institutional assessment (CPIA) as the guiding criterion. It argues that CPIA-centred allocation of aid fails to introduce an incentives structure supportive of a genuine donor-recipient partnership, conducive to development. Further, it claims that the CPIA-dependent debt thresholds-central to the new debt sustainability framework-effectively submit sustainability concerns to the policy performance prerogatives of the aid allocation system. Resting on a thin empirical basis, such approach fails to take due account of low-income countries' vulnerability to exogenous shocks, as a key determinant of debt distress. As an alternative to the current CPIA-based scheme, the paper outlines the key features of a state-contingent mechanism, guiding both aid allocation and debt sustainability analysis.foreign aid, economic development, aid allocation, debt sustainability

One share - one vote : a european rule?

In this paper, I tackle the question whether one share - one vote should become a European law rule. I examine, first of all, the economic theory concerning one share - one vote and its optimality, and the law and economics literature on dual class recapitalizations and other deviations from one share - one vote. I also consider the agency costs of deviations from one share - one vote and examine whether they justify regulation. I subsequently analyze the rules implementing the one share - one vote standard in the US and Europe. In particular, I analyze the self-regulatory rules of US exchanges, the relevant provisions of the European Takeover Directive (including the well known break-through rule), and the European Court of Justice's position as to golden shares (which also are deviations from the one share - one vote standard). I conclude that one share - one vote is not justified by economic efficiency, as also confirmed by comparative law. Also the European breakthrough rule, which ultimately strikes down all deviations from one share - one vote, does not appear to be well grounded. Only transparency rules appear to be justified at EU level as disclosure of ownership and voting structures serves a pricing and governance function, while harmonisation of the relevant rules reduces transaction costs in integrated markets

Women's Opportunities under Different Constellations of Family Policies in Western Countries: Inequality Tradeoffs Re-examined

Women’s rising labor force participation since the 1960’s was long seen as heralding decreasing gender inequalities. According to influential social science writings this view has now to be revised; “women friendly” policies bringing women into the workforce are held to create major inequality tradeoffs between quantity and quality in women’s jobs. Unintendedly, such policies increase employer statistical discrimination and create glass ceilings impeding women’s access to influential positions and high wages. This paper re-examines theoretical and empirical bases in analysis of family policy effects on gender inequalities. Including capabilities as well as earnings in definitions of gender inequality, we improve possibilities for causal analyses by mapping institutional constellations of separate dimensions of family policies in Western countries. Reflecting conflicting political forces as well as religion, contrary to accepted assumptions of uni-dimensionality, family policies are multi-dimensional, with main distinctions favoring traditional families, mother’s employment, or market reliance. Using multilevel analyses and broad sets of outcome variables, we show that methodological mistakes largely invalidate earlier causal interpretations of major tradeoffs between quantity and quality in women’s labor force participation. Positive policy effects facilitate work-family reconciliation and combine women’s increased labor force participation with relatively high fertility. While major negative policy effects for women with tertiary education are difficult to find, family policies clearly differ in the extent to which they improve opportunities for women without university degrees.-

Swedish parental leave and gender equality - Achievements and reform challenges in a European perspective

Sweden was the first country to introduce paid parental leave also to fathers in 1974, and this legislation has since then continuously been reformed in order to bring about a more equal parenthood. This study sets out to discuss the Swedish parental leave system and identify achievements, policy dilemmas and reform alternatives in a European perspective. The structure of parental insurance legislation, with earnings-related benefits and a long leave period, is often seen as a main explanation why Sweden has been able to combine relatively high fertility levels with high female labour force participation rates and low child poverty. In the perspective of changing demographic structures in Europe, with declining fertility levels and a growing number of elderly, the strengthening of dual earner family policies, including parental insurance legislation, may mitigate macro-economic and demographic problems by increasing gender equality and decreasing the work-family conflict. Despite the positive consequences, unresolved questions exist in the present parental leave legislation. The flexibility of the Swedish system, which still has extensive transferable leave rights, has the consequence that the lion’s share of parental leave days is still taken by mothers, among other things making it difficult for women to compete on equal terms with men in the labour market. Consequently, the gender-based division of parental leave may contribute to a preservation of traditional gender roles and inequalities. Another problem in the Swedish system is the work requirement for eligibility that excludes students and others with weak labour market attachment from the earnings-related benefits, possibly inflicting on the postponement of parenthood. Raising the minimum benefit could be one solution to enable childbearing among persons with weak labour market attachment, but this would also affect the economic incentives for paid work, and thus weaken the dual earner model.Parental leave; gender equality; reform challenges

Fuzzy cognitive maps outmatch loop analysis in dynamic modeling of ecological systems

Modeling natural systems is challenging due to their complexity in terms of variables, interactions, and dynamics. Much of this complexity is rooted in the existence of multiple ways through which acting variables affect each other. Besides the simple direct effects, numerous indirect effects emerge in ecological systems. Through an illustrative example, I exemplify here several advantages of fuzzy cognitive maps (FCM) over loop analysis (LA) in dynamic modeling of ecological systems. In addition to being able to incorporate information about the magnitude of variables interactions, FCM can make predictions about multiple simultaneous perturbations. Furthermore, FCM allow for the simulation of different magnitude of initial perturbations to the system. Last, FCM estimate the amount of variable increase/decrease, not just the likely direction of change. Hence, even if LA is still much more used than FCM in the scientific literature, FCM can be considered fitter than LA in modeling ecological systems

A new fuzzy algorithm for ecological ranking

Ecological ranking is a prerequisite to many kinds of environmental decisions. It requires a set of 'objects' (e.g., competing sites for species reintroduction, or competing alternatives of environmental management) to be evaluated on the basis of multiple weighted criteria, and then ranked from the best to the worst, or vice versa. The resulting ranking is then used to choose the course of an action (e.g., the optimal sites where a species can be reintroduced, or the optimal management scenario for a protected area). In this work, a new tool called FuzRnk is proposed as a modification of classic fuzzy algorithm. FuzRnk, which is freely available upon request from the author, allows for a fuzzy ranking of GIS objects (e.g., landscape patches or zones within protected areas). With respect to classic fuzzy algorithm, FuzRnk introduces two modifications: a) criteria can be weighted on the basis of their importance, b) not only the best performances, but also the worst ones are considered in the ranking procedure

Some thoughts on the control of network systems

The controllability of network-like systems is becoming a trendy key-issue in many disciplines, including ecology and biology. To control a biological, ecological or economic system is to make it behave according to our wishes, at the least possible cost. In this paper, I propose some ideas on networks control that do not precisely follow recent papers on the argument. By the way, since this scientific topic is still in open evolution, discordant thoughts might be helpful to the debate

Computing the uncertainty associated with the control of ecological and biological systems

Recently, I showed that ecological and biological networks can be controlled by coupling their dynamics to evolutionary modelling. This provides numerous solutions to the goal of guiding a system's behaviour towards the desired result. In this paper, I face another important question: how reliable is the achieved solution? In other words, which is the degree of uncertainty about getting the desired result if values of edges and nodes were a bit different from optimized ones? This is a pivotal question, because it's not assured that while managing a certain system we are able to impose to nodes and edges exactly the optimized values we would need in order to achieve the desired results. In order to face this topic, I have formulated here a 3-parts framework (network dynamics - genetic optimization - stochastic simulations) and, using an illustrative example, I have been able to detect the most reliable solution to the goal of network control. The proposed framework could be used to: a) counteract damages to ecological and biological networks, b) safeguard rare and endangered species, c) manage systems at the least possible cost, and d) plan optimized bio-manipulations