Tuning the average path length of complex networks and its influence to the emergent dynamics of the majority-rule model

We show how appropriate rewiring with the aid of Metropolis Monte Carlo computational experiments can be exploited to create network topologies possessing prescribed values of the average path length (APL) while keeping the same connectivity degree and clustering coefficient distributions. Using the proposed rewiring rules we illustrate how the emergent dynamics of the celebrated majority-rule model are shaped by the distinct impact of the APL attesting the need for developing efficient algorithms for tuning such network characteristics.Comment: 10 figure

Modeling Fisheries Agreements with Side Payments: The Case of Western Atlantic Bluefin Tuna

Though the management of internationally shared fisheries with side payments is often considered politically difficult, quota transferring is now a policy alternative in specific fisheries treaties. Nevertheless, a theoretical framework capturing the details of the side-payments solution is, to a large extend, missing. My thesis tries to fill this gap in the literature, by proposing a static and a dynamic model in the context of a stochastic sequentially harvested stock. The conditions characterizing the solution of the dynamic model are the analogue of the Martingale Property from finance literature. The Western Atlantic Bluefin Tuna fishery is used as an example to calibrate the theory. The objective is to estimate the amount of compensation Canada should provide to the US, such that the latter restricts fishing activities. The compensation scheme could supplement/reform the existing management strategies

Increasing the biorelevance of simulated intestinal fluids for better predictions of drug equilibrium solubility in the fasted upper small intestine

To date the importance of luminal species other than bile salts and phosphatidylcholine on drug equilibrium solubility in the fasted upper small intestine has been evaluated to a very limited extent. In this communication the importance of fatty acids, cholesterol, and proteins on solubility of four model lipophilic compounds was evaluated by including these components into previously proposed simulated intestinal fluids. Data were compared with ex vivo solubility data in aspirates reflecting the mean and the median luminal composition in the upper small intestine. It is concluded that estimation of solubility in aspirates reflecting the median luminal composition is better estimated when the presence of cholesterol and fatty acids is also simulated. In contrast, estimation of solubility in aspirates reflecting the mean luminal composition requires consideration of additional factors (e.g. buffer species identity, non-micellar colloidal structures, and lyso-phosphatidylcholine content)

Saccadic Eye Movements Modulate Visual Responses in the Lateral Geniculate Nucleus

AbstractWe studied the effects of saccadic eye movements on visual signaling in the primate lateral geniculate nucleus (LGN), the earliest stage of central visual processing. Visual responses were probed with spatially uniform flickering stimuli, so that retinal processing was uninfluenced by eye movements. Nonetheless, saccades had diverse effects, altering not only response strength but also the temporal and chromatic properties of the receptive field. Of these changes, the most prominent was a biphasic modulation of response strength, weak suppression followed by strong enhancement. Saccadic modulation was widespread, and affected both of the major processing streams in the LGN. Our results demonstrate that during natural viewing, thalamic response properties can vary dramatically, even over the course of a single fixation

On the effect of the path length and transitivity of small-world networks on epidemic dynamics

We show how one can trace in a systematic way the coarse-grained solutions of individual-based stochastic epidemic models evolving on heterogeneous complex networks with respect to their topological characteristics. In particular, we have developed algorithms that allow the tuning of the transitivity (clustering coefficient) and the average mean-path length allowing the investigation of the "pure" impacts of the two characteristics on the emergent behavior of detailed epidemic models. The framework could be used to shed more light into the influence of weak and strong social ties on epidemic spread within small-world network structures, and ultimately to provide novel systematic computational modeling and exploration of better contagion control strategies

Primate pre-arcuate cortex actively maintains persistent representations of saccades from plans to outcomes

Dorso-lateral prefrontal cortex is thought to contribute to adaptive behavior by integrating temporally dispersed, behaviorally-relevant factors. Past work has revealed a variety of neural representations preceding actions, which are involved in internal processes like planning, working memory and covert attention. Task-related activity following actions has often been reported, but so far lacks a clear interpretation. We leveraged modified versions of classic oculomotor paradigms and population recordings to show that post-saccadic activity is a dominant signal in dorso-lateral prefrontal cortex that is distinct from pre-saccadic activity. Unlike pre-saccadic activity, post-saccadic activity occurs after each saccade, although its strength and duration are modulated by task context and expected rewards. In contrast to representations preceding actions, which appear to be mixed randomly across neurons, post-saccadic activity results in representations that are highly structured at the single-neuron and population level. Overall, the properties of post-saccadic activity are consistent with those of an action memory, an internal process with a possible role in learning and updating spatial representations

Family Size, Intelligence, and Patterns of Achievement in Preschool Children

The purpose of this study was to investigate the relationship of membership in a large or small family to the patterns of achievement as revealed by the results of the subtests of the Iowa Test of Preschool Development (ITPD). Of interest also was the study of the relationship of membership in subgroups based on both race and family size to patterns of achievement. The subjects of the study were eighty black and white preschool children. There were twenty children in each subgroup small black family, large black family, small white family, and large white family). The subgroups were similar in respect to age and sex ratio. The ITPD was used to assess patterns of achievement. This test includes the subtests of Language, Visual-motor, Memory, and Concepts. A two-dimensional analysis of variance was used to determine the relationship between family size and the means of each subtest. None of the resultant F ratios were significant, indicating that family size is not related to success on the four subtests of the ITPD. The Duncan Multiple Range Test was calculated to ascertain the significance of the difference between the means of each pair of subgroup means. These subgroups were based on both family size and race. Comparisons between all possible combinations of subgroups allowed for the investigation of the differences between subgroup means based on family size within race, race within family size, and family size between races. Family size within race was significant in one of the eight possible comparisons. The children in large white families scored significantly higher than the children in small white families on the Visual-motor subtest. Race within family size us significant in several comparisons. On all four subtests of the ITPD, children in large white families scored significantly higher than children in large black families. The other significant difference was between the small family subgroups in which the white children scored higher than the black children on the Concepts subtest. Family size between races was also significant in several comparisons. The small white subgroup mean was significantly higher than the large black subgroup mean on the Language, Memory, and Concepts subtests. The other significant differences were between the small black and large white subgroups in which the large white subgroup scored significantly higher than the small black subgroup on both the Visual-motor and Concepts subtests. These results suggest that family size alone or family size within one race is not as significant in assessing patterns of achievement as is race when family size is held constant or the interaction of family size and race when both family size and race differ