574 research outputs found
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
Exploring the impact of Crohnâs disease on the intragastric environment of fasted adults
We explored the potential impact of Crohnâs disease on the intragastric environment of fasted adults with a view to potential effects on intragastric performance of orally administered drugs in the fasted state. Data were collected from 15 healthy individuals and 15 patients with Crohnâs disease. All subjects remained fasted for at least 12h prior to gastroscopy. Intragastric resting volume and pH were measured upon aspiration. Osmolality, surface tension, pepsin activity, and content of six bile acids were measured within 4 months upon sample collection. Unlike intragastric volumes, intragastric osmolality was significantly increased by Crohnâs disease. However, mean osmolality value in patients was only slightly higher than in healthy individuals (293 vs. 257 mOsmol/kg, respectively), therefore, unlikely to affect intragastric drug product performance. Primarily due to the high variability of data in healthy individuals, the potential effects on intragastric pH and surface activity could not be evaluated on a statistical basis. However, based on average (mean and median) values, even if they are statistically significant, it seems unlikely to be of clinical significance. Inter-subject variability of pepsin activity, and total bile acids content was high in both the healthy and the patientsâ groups. Statistical investigation of the potential impact of Crohnâs disease on these parameters requires prior designation of the minimum differences to be detected; such differences will determine the minimum sample size required of relevant investigations
- âŠ