What Do We Expect from Our Friends?

We conduct a field experiment in a large real-world social network to examine how subjects expect to be treated by their friends and by strangers who make allocation decisions in modified dictator games. While recipients’ beliefs accurately account for the extent to which friends will choose more generous allocations than strangers (i.e. directed altruism), recipients are not able to anticipate individual differences in the baseline altruism of allocators (measured by giving to an unnamed recipient, which is predictive of generosity towards named recipients). Recipients who are direct friends with the allocator, or even recipients with many common friends, are no more accurate in recognizing intrinsically altruistic allocators. Recipient beliefs are significantly less accurate than the predictions of an econometrician who knows the allocator’s demographic characteristics and social distance, suggesting recipients do not have information on unobservable characteristics of the allocator.dictator games, beliefs, baseline altruism, directed altruism, social networks

Directed Altruism and Enforced Reciprocity in Social Networks: How Much is A Friend Worth?

We conduct field experiments in a large real-world social network to examine why decision makers treat friends more generously than strangers. Subjects are asked to divide surplus between themselves and named partners at various social distances, where only one of the decisions is implemented. In order to separate altruistic and future interaction motives, we implement an anonymous treatment where neither player is told at the end of the experiment which decision was selected for payment and a non-anonymous treatment where both players are told. Moreover, we include both games where transfers increase and decrease social surplus to distinguish between different future interaction channels including signaling one's generosity and enforced reciprocity, where the decision maker treats the partner to a favor because she can expect it to be repaid in the future. We can decompose altruistic preferences into baseline altruism towards any partner and directed altruism towards friends. Decision makers vary widely in their baseline altruism, but pass at least 50 percent more surplus to friends compared to strangers when decision making is anonymous. Under non-anonymity, transfers to friends increase by an extra 24 percent relative to strangers, but only in games where transfers increase social surplus. This effect increases with density of the network structure between both players, but does not depend on the average amount of time spent together each week. Our findings are well explained by enforced reciprocity, but not by signaling or preference-based reciprocity. We also find that partners' expectations are well calibrated to directed altruism, but that they ignore decision makers' baseline altruism. Partners with high baseline altruism have friends with higher baseline altruism and are therefore treated better.

What Do We Expect from Our Friends?

We conduct a field experiment in a large real-world social network to examine how subjects expect to be treated by their friends and by strangers who make allocation decisions in modified dictator games. While recipients beliefs accurately account for the extent to which friends will choose more generous allocations than strangers (i.e. directed altruism), recipients are not able to anticipate individual differences in the baseline altruism of allocators (measured by giving to an unnamed recipient, which is predictive of generosity towards named recipients). Recipients who are direct friends with the allocator, or even recipients with many common friends, are no more accurate in recognizing intrinsically altruistic allocators. Recipient be- liefs are significantly less accurate than the predictions of an econometrician who knows the allocators demographic characteristics and social distance, suggesting recipients do not have information on unobservable characteristics of the allocator.dictator games, beliefs, baseline altruism, directed altruism, social networks

Directed Altruism and Enforced Reciprocity in Social Networks

We conduct online field experiments in large real-world social networks in order to decompose prosocial giving into three components: (1) baseline altruism toward randomly selected strangers, (2) directed altruism that favors friends over random strangers, and (3) giving motivated by the prospect of future interaction. Directed altruism increases giving to friends by 52 percent relative to random strangers, while future interaction effects increase giving by an additional 24 percent when giving is socially efficient. This finding suggests that future interaction affects giving through a repeated game mechanism where agents can be rewarded for granting efficiency enhancing favors. We also find that subjects with higher baseline altruism have friends with higher baseline altruism.modified dictator games, directed altruism, enforced reciprocity, social networks

CALCIFYING ACNE LESIONS

Cutaneous calcium deposition can occur in long-term inflammation. The deposition of calcium in long-standing acne may produce either small pigmented nodules or no visible lesions. The former type is much less common, with the nodules containing particulate spheres of mineral which probably represent true osteomas. Both types of calcification can be demonstrated roentgenographically and may occur in as many as half of all cases of severe long-standing acne.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65205/1/j.1365-4362.1977.tb01897.x.pd

A scanning electron microscopic study of hypercementosis

The purpose of this study was to evaluate morphological characteristics of teeth with hypercementosis that are relevant to endodontic practice. Twenty-eight extracted teeth with hypercementosis had their root apexes analyzed by scanning electron microscopy (SEM). The teeth were divided according to tooth groups and type of hypercementosis. The following aspects were examined under SEM: the contour and regularity of the root surface; presence of resorption; presence and number of apical foramina, and the diameter of the main foramen. The progression of club shape hypercementosis was directly associated with the presence of foramina and apical foramen obstruction. Cases of focal hypercementosis presented foramina on the surface, even when sidelong located in the root. Circular cementum hyperplasia form was present in 2 out of 3 residual roots, which was the highest proportion among the tooth types. The detection of a large number of foramina in the apical third of teeth with hypercementosis or even the possible existence of apical foramen obliteration contributes to understand the difficulties faced during endodontic treatment of these cases

Studies on the mechanism of phagocytosis. I. Requirements for circumferential attachment of particle-bound ligands to specific receptors on the macrophage plasma membrane

These experiments were designed to evaluate the role of macrophage plasma membrane receptors for the third component of complement (C) and for the Fc portion of IgG in the ingestion phase of phagocytosis. Sheep erythrocyte (E) were coated with anti-E IgG [E(IgG)]; these E(IgG) were then attached to cultivated monolayers of mouse peritoneal macrophages under conditions which reversibly inhibit ingestion of E(IgG). The E(IgG)-macrophage complexes were further incubated under similar conditions with an antimacrophage IgG fraction which blocks Fc receptor-mediated ingestion but has no effect upon ingestion mediated by other phagocytic receptors. When these cultures were subsequently incubated under conditions optimal for particle ingestion, phagocytosis of the IgG-coated erythrocytes did not occur; the erythrocytes remained bound to the Fc receptors of the macrophage plasma membrane. To determine whether ligands must cover the entire surface of an attached particle to permit ingestion of that particle, C-coated E [E(IgM)C] were bound to the C receptors of thioglycollate-induced (activated) macrophages at 4 degrees C. E(IgM)C-macrophage complexes were then trypsinized at 4 degrees C, a procedure which resulted in cleavage of erythrocyte-bound C3b molecules to a form of C3 not recognized by the macrophage receptors for C3b. Under the conditions used, trypsin did not affect the attachment of E(IgM)C to the macrophage surface or the macrophage receptors for C3b. When these trypsin treated E(IgM)C-macrophage complexes were incubated at 37 degrees C, the bound E(IgM)C were not ingested; the erythrocytes remained attached to the macrophage plasma membrane via the macrophage's C receptors. These results indicate that attachment of a particle to specific receptors on the macrophage plasma membrane is not sufficient to trigger ingestion of that particle. Rather, ingestion requires the sequential, circumferential interaction of particle-bound ligands with specific plasma membrane receptors not involved in the initial attachment process

Assessing the relationship between district and state policies and school nutrition promotion-related practices in the United States

School environments are an optimal setting to promote healthy student diets, yet it is unclear what role state and district policies play in shaping school contexts. This study examined how state and district policies are associated with school-reported practices for promoting student participation in school lunch programs. School nutrition manager data were obtained from the School Nutrition and Meal Cost Study\u27s (SNMCS) sample of 1210 schools in 46 states and the District of Columbia (DC) during school year 2014-2015. Relevant state laws and district policies were compiled and coded. Multivariable logistic and Poisson regressions, controlling for school characteristics, examined the relationship between state/district laws/policies and school practices. Compared to schools in districts or states with no policies/laws, respectively, schools were more likely to provide nutritional information on school meals (AOR = 2.59, 95% CI = 1.33, 5.05) in districts with strong policies, and to promote school meals at school events (AOR = 1.93, CI = 1.07, 3.46) in states with strong laws. Schools in states with any laws related to strategies to increase participation in school meals were more likely to seek student involvement in menu planning (AOR = 2.02, CI = 1.24, 3.31) and vegetable offerings (AOR = 2.00, CI = 1.23, 3.24). The findings support the association of laws/policies with school practices

Financial Structure and Economic Welfare: Applied General Equilibrium Development Economics

This review provides a common framework for researchers thinking about the next generation of micro-founded macro models of growth, inequality, and financial deepening, as well as direction for policy makers targeting microfinance programs to alleviate poverty. Topics include treatment of financial structure general equilibrium models: testing for as-if-complete markets or other financial underpinnings; examining dual-sector models with both a perfectly intermediated sector and a sector in financial autarky, as well as a second generation of these models that embeds information problems and other obstacles to trade; designing surveys to capture measures of income, investment/savings, and flow of funds; and aggregating individuals and households to the level of network, village, or national economy. The review concludes with new directions that overcome conceptual and computational limitations.National Science Foundation (U.S.)National Institutes of Health (U.S.)Templeton FoundationBill & Melinda Gates Foundatio

Gender Differences in Sleep Deprivation Effects on Risk and Inequality Aversion: Evidence from an Economic Experiment

Excessive working hours—even at night—are becoming increasingly common in our modern 24/7 society. The prefrontal cortex (PFC) is particularly vulnerable to the effects of sleep loss and, consequently, the specific behaviors subserved by the functional integrity of the PFC, such as risk-taking and pro-social behavior, may be affected significantly. This paper seeks to assess the effects of one night of sleep deprivation on subjects’ risk and social preferences, which are probably the most explored behavioral domains in the tradition of Experimental Economics. This novel cross-over study employs thirty-two university students (gender-balanced) participating to 2 counterbalanced laboratory sessions in which they perform standard risk and social preference elicitation protocols. One session was after one night of undisturbed sleep at home, and the other was after one night of sleep deprivation in the laboratory. Sleep deprivation causes increased sleepiness and decreased alertness in all subjects. After sleep loss males make riskier decisions compared to the rested condition, while females do the opposite. Females likewise show decreased inequity aversion after sleep deprivation. As for the relationship between cognitive ability and economic decisions, sleep deprived individuals with higher cognitive reflection show lower risk aversion and more altruistic behavior. These results show that one night of sleep deprivation alters economic behavior in a gender-sensitive way. Females’ reaction to sleep deprivation, characterized by reduced risky choices and increased egoism compared to males, may be related to intrinsic psychological gender differences, such as in the way men and women weigh up probabilities in their decision-making, and/or to the different neurofunctional substrate of their decision-making.The authors acknowledge financial support from the Spanish Ministry of Economic Competititveness (ECO2012-34928), Italian Ministry of University and Research MIUR (PRIN 20103S5RN3_002), Generalitat Valenciana (Research Projects Gruposo3/086), the Instituto Valenciano de Investigaciones Económicas (IVIE), and the Ministero della Salute (RF-2009-1528677)