Network Organizations

It is common to define a network organization as one that is fast and flexible in adapting to changes in the underlying environment. But besides the short-run advantages of adaptability, fast changes in the structure of the organization can also be detrimental in the longer run. This happens, in particular, because agents need to depend widely on that structure to channel appropriately (and thus speed up) search. I discuss the trade-off between adaptability and structural stability in a changing environment where, if the structure of the organization adjusts, information on the exact nature of the change becomes known only with some lag. The main conclusion obtained is that, as environment becomes more volatile, the optimal mode of the organization sharply switches from being totally flexible to being completely rigid, i.e. no intermediate configurations are essentially ever optimal. This has stark implications on the dichothomy of stability versus change that has been highlighted by recent organization literature.

Building Up Social Capital in a Changing World: A Network Approach

This paper models the dynamic process through which a large society may succeed in building up its “social capital” by establishing a stable and dense pattern of interaction among its members. In the model, agents interact according to a collection of infinitely repeated Prisoner’s Dilemmas played on the current social network. This network not only specifies the playing partners but, crucially, also determines how relevant strategic information diffuses or new cooperation opportunities are found. Over time, the underlying payoffs randomly change, i.e. display some “volatility”, which leads agents to react by creating new links and removing others. The process is ergodic, so we use numerical simulations to “compute” its long-run invariant behavior and obtain the following conclusions: (a) Only if payoff volatility is not too high can the society sustain a dense social network. (b) The social architecture endogenously responds to increased volatility by becoming more cohesive. (c) Network-based strategic effects are an essential buffer that preclude the abrupt collapse of the social network in the face of growing volatility. These conclusions, largely in tune with those of the social-capital literature, are further studied analytically in a companion paper through the use of mean-field techniques.Social Capital, Prisoner's Dilemma, Search, Social Networks, Volatility

BUILDING UP SOCIAL CAPITAL IN A CHANGING WORLD

This paper models the dynamic process through which a large society may succeed in building up its "social capital" by establishing a stable and dense pattern of interaction among its members. In the model, agents interact according to a collection of (idyosincratic) infinitely repeated Prisoner's Dilemma played on the existing social network. This network not only specifies the playing partners but, crucially, also determines how relevant strategic information diffuses or new cooperation opportunities are found. Over time, the underlying payoffs randomly change, i.e. display some "volatility". In response to it, agents react by creating new links and removing others. This combines into a complex but ergodic dynamic process, whose analysis is undertaken in different ways. First, we rely on its ergodicity to "compute" numerically its long-run regularities. Second, we use mean-field approximations to derive analytical results. Both routes are found in accord and also complementary. The long-run dynamics of the process sharply depends on environmental volatility, displaying the following features: (a) Only if volatility is not too high can the society sustain a dense social network and thus attain a large average payoff. (b) The social architecture endogenously responds to increased volatility by becoming more cohesive. (c) Network-based strategic effects are an essential buffer that preclude the abrupt collapse of the social network in the face of growing volatility. These conclusions are largely in tune with the points stressed in the social-capital literature.social capital, volatility.

The contrastive value of lexical stress in visual word recognition: Evidence from spanish

Resumen tomado de la publicaciónEl valor contrastivo del acento léxico en el reconocimiento visual de palabras: evidencia del español. Antecedentes: muchos pares de palabras en español, en particular muchas formas verbales, difieren solo en la sílaba acentuada, tal como aNImo y aniMÓ. Así el acento puede adquirir un valor contrastivo que fue confirmado por Dupoux, Pallier, Sebastian y Mehler (1997) en español, pero no en francés, en percepción auditiva. Método: este estudio contrasta el efecto de primado en pares de palabras que difieren en su patrón de acentuación con el efecto de repetición, el primado solo de acento (sin relación ortográfica) y el primado morfológico en reconocimiento visual de palabras. Resultados: usando priming enmascarado se obtuvo facilitación para los pares con diferente acento (rasGÓ/RASgo) comparando con los pares sin relación (dorMÍ/RASgo), pero no se produjo comparando con los no relacionados de igual acento (PERsa/RASgo). Sin embargo, los pares idénticos (RASgo-RASgo) produjeron facilitación comparando con ambas condiciones ortográficamente relacionadas. Con un SOA largo los pares con diferente acento (ortográficamente iguales) produjeron una facilitación significativa, como ocurrió con los pares relacionados morfológicos (RASga/RASgo), sobre los pares ortográficamente diferentes (PERsa/RASgo). Conclusión: estos resultados confirman la importancia del procesamiento temprano y preléxico del acento para la selección léxica en español, como ocurre con las características ortográficas y fonológicas de las palabras.Universidad de Oviedo. Biblioteca de Psicología; Plaza Feijoo, s/n.; 33003 Oviedo; Tel. +34985104146; Fax +34985104126; [email protected]

LEARNING, NETWORK FORMATION AND COORDINATION

In many economic and social contexts, individual players choose their partners and also decide on a mode of behavior in interactions with these partners. This paper develops a simple model to examine the interaction between partner choice and individual behavior in games of coordination. An important ingredient of our approach is the way we model partner choice: we suppose that a player can establish ties with other players by investing in costly pair-wise links. We show that individual efforts to balance the costs and benefits of links sharply restrict the range of stable interaction architectures; equilibrium networks are either complete or have the star architecture. Moreover, the process of network formation has powerful effects on individual behavior: if costs of forming links are low then players coordinate on the risk-dominant action, while if costs of forming links are high then they coordinate on the efficient action.Networks, social learning, equilibrium selection

Network Formation and Social Coordination

This paper develops a simple model to examine the interaction between partner choice and individual behavior in games of coordination. An important ingredient of our approach is the way we model partner choice: we suppose that a player can establish ties with other players by unilaterally investing in costly pair-wise links. In this context, individual efforts to balance the costs and benefits of links are shown to lead to a unique equilibrium interaction architecture. The dynamics of network formation, however, has powerful effects on individual behavior: if costs of forming links are below a certain threshold then players coordinate on the risk-dominant action, while if costs are above this threshold then they coordinate on the efficient action. These findings are robust to a variety of modifications in the link formation process. For example, it may be posited that, in order for a link to materialize, the link proposal must be two-sided (i.e. put forward by both agents); or that, in case of a unilateral proposal, the link may be refused by the other party (if, say, the latter's net payoff is negative); or that a pair of agents can play the game even if connected only through indirect links.Networks, Links, Coordination games, Equilibrium selection, Risk dominance, Efficiency

Search and Homophily in Social Networks

We study the formation of social ties among heteogeneous agents in a model where meetings are governed by agents' directed search. The aim is to shed light on the important issue of homophily (the tendency of agents to connect with others of the same type). The essential contribution of the model is to provide a basic microfoundation for the opportunity/meeting biases that, as the literature highlights, are a crucial element of the phenomenon. Under the assumption that search is more effective in large pools, the equilibrium is characterized by a threshold in terms of group size: large groups only search among similar agents while smaller groups search in the whole population. This threshold behavior is consistent with the empirical evidence observed in a range of social environments such as high school friendships and interethnic marriages. And assuming that search is subject to small frictions, it also generates the bell-shaped form of the so-called Coleman index observed in the data. Other implications of the model supported by the evidence concern the pattern of cross-group ties among small groups, the linearity of excess homophily for large groups, and the positive effect on it of overall population size.Homophily, search, social networks, segregation.

Good living-Sumak Kawsay in the Constitution and in the PNBV 2013-2017 of Ecuador

El presente artículo, en su parte central, trata de exponer de manera más o menos sucinta la importancia del concepto del Sumak Kausay en la Constitución ecuatoriana y en el Plan Nacional del Buen vivir 2013-2017, mostrando sus continuidades y diferencias que obedecen, unas y otras, a los distintos momentos políticos en los que estos dos documentos han sido producidos: la Constitución, en el año 2008 en los inicios de la “revolución ciudadana” y el Plan del Buen Vivir, tras la reelección de Rafael Correa para un nuevo período presidencial en 2013. En una breve introducción se da cuenta del contexto histórico ecuatoriano antecedente, que permite la irrupción del Sumak Kawsay y en las conclusiones se recogen algunos ecos del debate político que tanto en Ecuador como en Bolivia se están produciendo frente a los intentos gubernamentales de pasar del discurso del Buen Vivir a los programas y proyectos de la política real.This article, in its central part, tries to expose more or less succinctly the importance of the concept of “Sumak kausay” in the Ecuadorian Constitution and the National Plan for Good Living 2013-2017, showing continuities and differences that obey a and others, the different political moments in which these two documents have been produced: the Constitution, in 2008 at the beginning of the "citizen revolution" and the Plan of Good Living/Living Well, following the re-election of Rafael Correa for a new presidential term in 2013. During a brief introduction realizes the Ecuadorian historical context background, allowing the emergence of “Sumak Kawsay” and conclusions some echoes of the political debate over attempts are both Ecuador and Bolivia producing collected government spending Speech Good Living/Living Well programs and projects of real politics

Ultrasonographic evaluation of fetal heart rate in Colombian Creole Mares

P?ginas 32-36Recurso Electr?nicoEl objetivo de esta investigaci?n fue establecer por ultrasonograf?a, la frecuencia card?aca fetal, desde el mes cuarto hasta el final de la gestaci?n en 20 yeguas criollas colombianas, con edades entre los cuatro a los ocho a?os y un peso promedio de 348 ? 8,69 kg, mediante examen transrectal y transabdominal, utilizando un transductor lineal endorectal de 6,0 MHz y un sectorial convexo R40 de 3,5 MHz. Se encontraron diferencias estad?sticas significativas (p ? 0,05) en la frecuencia card?aca de los fetos a lo largo de la gestaci?n frente a las reportadas en equinos de otras razas, en el cuarto mes de gestaci?n la media de la frecuencia card?aca fetal en latidos por minuto fue de 145 ? 6,82 y de 86 ? 5,28 en el ?ltimo mes de gestaci?n, observ?ndose una disminuci?n lineal gradual de la frecuencia card?aca al aumentar el tiempo gestacional.ABSTRACT. The objective of this research was to establish the fetal heart rate in pregnant Colombian creole mares by ultrasonography. The study was carried out, from the fourth month to end of gestation in 20 creole mares, aged four to eight-year-old, and an average body-weight of 348 ? 8.69 kg. The examination was performed via transrectal with a 6.0 MHz linear transducer and by transabdominal examination with a R40 3.5 MHz convex sector transducer. Significant statistical differences (p ? 0.05) in the fetal heart rate of pregnant Colombian mares were found throughout the gestation period compared to the fetal rate reported in females of other equine breeds. In the fourth month of gestation, mean fetal heart rate in beats per minute was 145 ? 6.82 and 86 ? 5.28 in the last month of gestation, showing a gradual linear decrease in heart rate with increasing gestational time