2,702 research outputs found

    THE MYSTERY OF MONOGAMY

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    This paper examines why developed countries are monogamous while rich men throughout history have tended to practice polygyny (multiple wives). Wealth inequality naturally produces multiple wives for rich men in a standard model of the marriage market. This paper argues that the sources of inequality, not just the level of inequality, determine the equilibrium degree of monogamy or polygamy. In particular, when inequality is determined more by disparities in human capital versus non-labor income (such as land, capital, corruption), the outcome is more monogamous. This explains why developed countries, where human capital is the main source of income and inequality, are monogamous while less-developed economies tend to be polygynous. The results are driven by the larger inequality in the value of women in the marriage market in modern economies. When the value of human capital increases, rich men increasingly value quality women who can help them raise quality children more efficiently. As a result, high quality women are valued much more than low quality women, which makes polygyny less affordable for rich men. In this manner, we show that male inequality generates polygyny, but female inequality reduces it. Using data from Cote d'Ivoire, we provide evidence for all the main implications of the model. In particular, we control for a man's total income and show that polygyny increases with non-labor income but decreases with labor income and education. These patterns are strong even within social groups where norms regarding polygyny are likely to be constant.Marriage, Monogamy, Polygyny, Human Capital, Inequality, J12, J24, O10, O40, Labor and Human Capital,

    Does high inequality attract high skilled immigrants?

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    This study examines how the sources and levels of income inequality affect how a country attracts and retains high skilled workers. With parameter values that yield realistic levels of emigration, our model shows that emigration rates increase with education when the returns to education are higher abroad. However, the relationship between unobservable skills (‘residual wages’) and emigration can display an inverse U-shaped pattern, if unobservable skills are composed of both ‘general’ and ‘country-specific’ skills. Using data on Israeli emigrants before they decide to emigrate, we find strong empirical evidence in support of the model's predictions

    Relativistic Photon Mediated Shocks

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    A system of equations governing the structure of a steady, relativistic radiation dominated shock is derived, starting from the general form of the transfer equation obeyed by the photon distribution function. Closure is obtained by truncating the system of moment equations at some order. The anisotropy of the photon distribution function inside the shock is shown to increase with increasing shock velocity, approaching nearly perfect beaming at upstream Lorentz factors Γ>>1\Gamma_{-}>>1. Solutions of the shock equations are presented for some range of upstream conditions. These solutions are shown to converge as the truncation order is increased.Comment: 5 pages, a shorter version will appear in PR

    Blunted Cystine–Glutamate Antiporter Function in the Nucleus Accumbens Promotes Cocaine-induced Drug Seeking

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    Repeated cocaine alters glutamate neurotransmission, in part, by reducing cystine–glutamate exchange via system xc−, which maintains glutamate levels and receptor stimulation in the extrasynaptic compartment. In the present study, we undertook two approaches to determine the significance of plasticity involving system xc−. First, we examined whether the cysteine prodrug N-acetylcysteine attenuates cocaine-primed reinstatement by targeting system xc−. Rats were trained to self-administer cocaine (1 mg/kg/200 μl, i.v.) under extended access conditions (6 h/day). After extinction training, cocaine (10 mg/kg, i.p.) primed reinstatement was assessed in rats pretreated with N-acetylcysteine (0–60 mg/kg, i.p.) in the presence or absence of the system xc− inhibitor (S)-4-carboxyphenylglycine (CPG; 0.5 μM; infused into the nucleus accumbens). N-acetylcysteine attenuated cocaine-primed reinstatement, and this effect was reversed by co-administration of CPG. Secondly, we examined whether reduced system xc− activity is necessary for cocaine-primed reinstatement. To do this, we administered N-acetylcysteine (0 or 90 mg/kg, i.p.) prior to 12 daily self-administration sessions (1 mg/kg/200 μl, i.v.; 6 h/day) since this procedure has previously been shown to prevent reduced activity of system xc−. On the reinstatement test day, we then acutely impaired system xc− in some of the rats by infusing CPG (0.5 μM) into the nucleus accumbens. Rats that had received N-acetylcysteine prior to daily self-administration sessions exhibited diminished cocaine-primed reinstatement; this effect was reversed by infusing the cystine–glutamate exchange inhibitor CPG into the nucleus accumbens. Collectively these data establish system xc− in the nucleus accumbens as a key mechanism contributing to cocaine-primed reinstatement

    Developing Multi Linear Regression Models for Estimation of Marshall Stability

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    Nowadays, asphalt roads are exposed to increasing traffic loads in recent times. It is important to obtain a quality and healthy asphalt road covering when considering the conditions of our country where freight and passenger transportation are carried out by roads. One of the most important issues in asphalt road design is the determination of the optimum percentage of bitumen. The Marshall stability test is utilized for optimum percent bitumen determination. In our work, instead of the long and laborious Marshall experiment process, Multi Linear Regression (MLR) Models are developed as an alternative. Models were developed for Marshall experiment result for Marshall stability prediction. In order to construct stability estimation models, pre-made test parameters are used. These parameters are; the bitumen penetration (P),weight of the sample in the weather (H), the temperature (C), the bitumen weight (G), the sample heights (Y), the bitumen percentage (W), weight of the sample in water (S), the stability (ST). In the performance evaluation of the models, the correlation coefficient (R), the mean percentage errors (MPE) and the meansquare errors (MSE) are used. It is seen that the model with the highest performance value is composed of six variable model in this study formed by the MLR. The R value of the best model is 0.571.The MSE value of the best model is 14841,81. The MPE value of the best model is 9.58

    Improving the efficiency of repair-technical service of production by using the concept of total productive maintenance

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    Материалы XVIII Междунар. науч.-техн. конф. студентов, аспирантов и молодых ученых, Гомель, 26–27 апр. 2018 г
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