Social Identity and Social Value Orientations

This study provides an extension of the social value orientation model and a tool, other-other Decomposed Games, to quantify the influence of social iden- tity on social value orientations. Social identity is induced experimentally using the minimal group paradigm. Subsequently, the weights subjects add to the outcomes of outgroup others relative to ingroup others and to the absolute difference between the outcomes of ingroup and outgroup others are estimated. Results are compared to a control condition in which social identity is not induced. Results show that when the outgroup is better off than the ingroup, the average subject is spiteful: they derive negative utility from the outcomes of the outgroup other. When the ougroup is worse off than the ingroup, the average subject attaches similar weights to the outcomes of outgroup and ingroup others. There is also significant variation across subjects with respect to the level of ingroup bias

The Politics behind the Veil

Using a natural experiment, we find that in provinces where Turkey’s Islamic Justice and Development Party (AKP) just won the election in 2004, women, including those who are weakly religious or non-religious, now veil far more than in provinces in which AKP just lost, the more so the poorer they are. This effect, as we predict, does not occur for praying regularly which is more costly and harder to observe practice. We argue that veiling is higher in AKP provinces not only because of a generic aim to conform to the stricter mores fostered by the victorious party. We find that those who veil, particularly those in AKP provinces who are not pious, are more politically active than those who do not veil. This may be an indication that veiling could partly be a strategic response to policies, which favour those who are or appear pious. Our study suggests that observable religious practices may have their independent dynamics driven by the pursuit of instrumental goals. Our results also suggest that parties with a religious ideology have an advantage over their secular counterparts in solving the clientelistic information problem, for they can rely on religious symbols for screening and signalling

Maximum likelihood estimation of Gaussian mixture models using stochastic search

Cataloged from PDF version of article.Gaussian mixture models (GMM), commonly used in pattern recognition and machine learning, provide a flexible probabilistic model for the data. The conventional expectation-maximization (EM) algorithm for the maximum likelihood estimation of the parameters of GMMs is very sensitive to initialization and easily gets trapped in local maxima. Stochastic search algorithms have been popular alternatives for global optimization but their uses for GMM estimation have been limited to constrained models using identity or diagonal covariance matrices. Our major contributions in this paper are twofold. First, we present a novel parametrization for arbitrary covariance matrices that allow independent updating of individual parameters while retaining validity of the resultant matrices. Second, we propose an effective parameter matching technique to mitigate the issues related with the existence of multiple candidate solutions that are equivalent under permutations of the GMM components. Experiments on synthetic and real data sets show that the proposed framework has a robust performance and achieves significantly higher likelihood values than the EM algorithm. (C) 2012 Elsevier Ltd. All rights reserved

Effect of seminal plasma on functional integrity of rabbit sperm membranes during storage at 4ºC or freezing

[EN] The effect of semen plasma removal either by simple centrifugation or by separation through a Percoll gradient on the integrity of plasma membranes of rabbit spermatozoa during storage at 4°C and freezing was evaluated in two successive experiments. A modifi ed hypo-osmotic swelling test procedure combined with supravital staining was employed to evaluate simultaneously membrane integrity of head and tail membranes of sperm cells. In the first experiment, the impact of semen plasma on membrane integrity of sperm cells was examined in Tris-citric acid-glucose extender at 4°C for 96 h. The percentage of sperm cells with disintegrated tail and head membranes increased in all groups in correlation with the length of storage. After storage for 96 h, removal of semen plasma, irrespective of the method of removal, resulted in signifi cant increase (P<0.01) in the percentage of sperm cells with disintegrated plasma membranes. The adverse effect of storage and removal of semen plasma was more prominent on the tail membranes, and especially during the fi rst 24 h of the storage period. In the second experiment, the impact of semen plasma on membrane integrity of sperm cells undergoing freezing was examined. A total of three groups were arranged as described in the fi rst experiment, and semen samples were frozen in straws using an extender including acetamide and methyl cellulose. Freezing of semen drastically reduced the percentage of sperm cells with intact plasma membranes in postthaw samples. However, removal of semen plasma, irrespective of the method of removal, did not affect the proportion of sperm cells with intact plasma membranes. In conclusion, the effect of semen plasma on plasma membranes varied signifi cantly relative to the preservation temperature of sperm cells. Although it exerted a protective infl uence during storage at 4°C, no protective impact was monitored during freezing.Aksoy, M.; Cankat Lehimcioglu, N.; Akman, O. (2010). Effect of seminal plasma on functional integrity of rabbit sperm membranes during storage at 4ºC or freezing. World Rabbit Science. 16(1). doi:10.4995/wrs.2008.64216

Regression Discontinuity diagnostics reveal statistical anomalies in Turkish elections

Using Regression Discontinuity diagnostics we document a number of statistical anomalies in the 2004 Turkish mayoral elections. The governing party that controls the parliament is much more likely to win close races than lose. Moreover, compared to close governing party losses, there is a sharp drop in turnout and contending party votes in close governing party wins. Finally, the parties that disproportionately lose very close races are exclusively ideological competitors of the governing party. Among the potential mechanisms that may create those anomalies, electoral manipulation seems to a plausible explanation. Those anomalies show that the outcomes of very close popular elections can be non-random and that the assumption of the continuity of the expected potential outcomes at the threshold could be violated. We discuss implications of our findings for Regression Discontinuity Designs and for understanding the consolidation of the right-wing electorate in Turkey during the last decade

Effects of Heterogeneity and Homophily on Cooperation

The article provides a micro-behavioral model and an experimental design to understand the effect of heterogeneity in social identities on cooperation while accounting for endogenous sorting. Social identity is induced exogenously using the minimal group paradigm. The experiment manipulates sorting with three treatments: having subjects interact with both in- and outgroup members, giving them the choice to interact either with ingroup or outgroup members, and isolating the groups from the outset. Cooperation is measured by the Prisoner’s Dilemma Games at the dyadic level and by Public Goods Games at the tetradic level. The results show that heterogeneity hampers between-group cooperation at the dyadic level. In addition, endogenous sorting mitigates this negative effect of heterogeneity on cooperation. Heterogeneity hampers cooperation at the tetradic level most substantially if there is a commonly known negative history between groups

Motherhood, sex of the offspring, and religious signaling

Using Turkey’s 2013 Demographic and Health Survey, I find that among married women, having a single child as opposed to no children is associated with an approximately five-percentage-point increase in the likelihood of religious veiling. Furthermore, the likelihood of religious veiling increases as the number of a woman’s children increases. Robustness checks show that these associations are rather stable across the Muslim world. In addition, I use the sex of a woman’s first child as a natural experiment and find that in Turkey, having a son versus a daughter increases the likelihood of religious veiling by 2.2 percentage points. In contrast, having a child and the sex of the first child have no significant effects on unobservable religious behaviors, traditional values, and gender norms. These results are consistent with the hypothesis derived from signaling theory that women use veiling strategically to foster family reputation

Heating of magnetic fluid systems driven by circularly polarized magnetic field

Cataloged from PDF version of article.A theory is presented to calculate the heat dissipation of a magnetic suspension, a ferrofluid, driven by7 circularly polarized magnetic field. Theory is tested by in vitro experiments and it is shown that, regardless of the character of the relaxation process, linearly and circularly polarized magnetic field excitations, having the same root-mean-square magnitude, are equivalent in terms of heating efficiency. (C) 2010 Elsevier B.V. All rights reserved