Social Fractionalization, Endogenous Property Rights, and Economic Development

We investigate how social composition affects competitive and cooperative behavior in a linear growth model without a priori secure property rights. If a society is homogenous or highly fractionalized it is in the self-interest of people to cooperate. The first best allocation is enforced through trigger strategies, property rights turn out to be secure, and growth is independent from social fractionalization. If a society is polarized, i.e. if it consists of a small number of equally sized groups, property rights can turn out as unenforceable. If so, groups follow an exploitive strategy that leads to low investment and growth. In this case the rate of growth is continuously decreasing in the degree of fractionalization and possibly negative.Africa’s growth tragedy; property rights; social fractionalization; differential games; trigger strategies

Picture Policies in Documents : Visual Display and Epistemic Practices

This essay discusses the specific relationships between images and text in the journal Documents which Georges Bataille edited from 1929 to 1930. Visual display is of central importance in the publication, the images do not illustrate, they operate on the same plane as the text, and the dynamics created through their interplay are decisive. They shape the attack on scientific discourse and every kind of idealism. The journal did not survive beyond the second year, but it became a catalyst for those involved and a source of postmodern thinking through its picture policies.Cet article analyse la spécificité des relations entre texte et image dans la revue Documents dirigée par Georges Bataille de 1929 à 1930. La disposition visuelle s’avère essentielle dans cette publication : les images n’illustrent pas le texte, elles ne lui sont pas subordonnées. Au contraire, l’interaction dynamique entre les deux compose la force critique qui vient miner tout discours scientifique et idéaliste. Documents n’existera guère plus de deux ans mais devint un catalyseur important pour ses collaborateurs et une source de la pensée postmoderne, notamment à travers ses stratégies visuelles

The Prediction value

We introduce the prediction value (PV) as a measure of players' informational importance in probabilistic TU games. The latter combine a standard TU game and a probability distribution over the set of coalitions. Player $i$'s prediction value equals the difference between the conditional expectations of $v(S)$ when $i$ cooperates or not. We characterize the prediction value as a special member of the class of (extended) values which satisfy anonymity, linearity and a consistency property. Every $n$-player binomial semivalue coincides with the PV for a particular family of probability distributions over coalitions. The PV can thus be regarded as a power index in specific cases. Conversely, some semivalues -- including the Banzhaf but not the Shapley value -- can be interpreted in terms of informational importance.Comment: 26 pages, 2 table

Simple “Market Value” Bargaining Model for Weighted Voting Games: Characterization and Limit Theorems

Feld, Grofman and Ray (2003) offer a bargaining model for weighted voting games that is a close relative of the nucleolus and the kernel. They look for a set of weights that preserves winning coalitions that has the property of minimizing the difference between the weight of the smallest and the weight of the largest Minimum Winning Coalition. They claim that such a set of weights provides an a priori measure of a weighted voter’s bribeworthiness or market value. Here, after reviewing the basic elements of their model, we provide a characterization result for this model and show its links to other bargaining model approaches in the literature. Then we offer some limit results showing that, with certain reasonable conditions on the distributions of weights, as the size of the voting body increases, the values of bribeworthiness we calculate will approach both the weights themselves and the Banzhaf scores for the weighted voting game. We also show that, even for relatively small groups using weighted voting, such as the membership of the European Council of Ministers (and its precedessors) 1958-2003, similarities among the usual a priori power scores, bribeworthiness/market value, and the weights themselves, will be quite strong

Naïve learning in social networks with random communication

We study social learning in a social network setting where agents receive independent noisy signals about the truth. Agents naïvely update beliefs by repeatedly taking weighted averages of neighbors’ opinions. The weights are fixed in the sense of representing average frequency and intensity of social interaction. However, the way people communicate is random such that agents do not update their belief in exactly the same way at every point in time. Our findings, based on Theorem 1, Corollary 1 and simulated examples, suggest the following. Even if the social network does not privilege any agent in terms of influence, a large society almost always fails to converge to the truth. We conclude that wisdom of crowds seems an illusive concept and bares the danger of mistaking consensus for truth

Networks and collective action

Given a social network, we are interested in the problem of measuring the influence of a group of agents to lead the society to adopt their behavior. Motivated by the description of terrorist movements, we provide a markovian dynamical model for non-symmetric societies, which takes into account two special features: the hard core terrorist group cannot be influenced, and the remaining agents may change from active to non-active and vice versa during the process. In this setting, we interpret the absorption time of the model, which measures how quickly the terrorist movement achieve the support of all society, as a group measure of power. In some sense, our model generalizes the classical approach of DeGroot to consensus formatio

Beta-escin has potent anti-allergic efficacy and reduces allergic airway inflammation

<p>Abstract</p> <p>Background</p> <p>Type I hypersensitivity is characterized by the overreaction of the immune system against otherwise innocuous substances. It manifests as allergic rhinitis, allergic conjunctivitis, allergic asthma or atopic dermatitis if mast cells are activated in the respective organs. In case of systemic mast cell activation, life-threatening anaphylaxis may occur. Currently, type I hypersensitivities are treated either with glucocorticoids, anti-histamines, or mast cell stabilizers. Although these drugs exert a strong anti-allergic effect, their long-term use may be problematic due to their side-effects.</p> <p>Results</p> <p>In the course of a routine <it>in vitro </it>screening process, we identified beta-escin as a potentially anti-allergic compound. Here we tested beta-escin in two mouse models to confirm this anti-allergic effect <it>in vivo</it>. In a model of the early phase of allergic reactions, the murine passive cutaneous anaphylaxis model, beta-escin inhibited the effects of mast cell activation and degranulation in the skin and dose-dependently prevented the extravasation of fluids into the tissue. Beta-escin also significantly inhibited the late response after antigen challenge in a lung allergy model with ovalbumin-sensitized mice. Allergic airway inflammation was suppressed, which was exemplified by the reduction of leucocytes, eosinophils, IL-5 and IL-13 in the bronchoalveolar lavage fluid. Histopathological examinations further confirmed the reduced inflammation of the lung tissue. In both models, the inhibitory effect of beta-escin was comparable to the benchmark dexamethasone.</p> <p>Conclusions</p> <p>We demonstrated in two independent murine models of type I hypersensitivity that beta-escin has potent anti-allergic properties. These results and the excellent safety profile of beta-escin suggest a therapeutic potential of this compound for a novel treatment of allergic diseases.</p