Lightning Talk: Biopython (bio) Geography Module

For Google Summer of Code 2009/NESCENT Phyloinformatics Summer of Code 2009, I built a Geography module for Biopython. The purpose of the module is to search, download, and process biogeographical data from GBIF, much as Biopython currently accesses Genbank. Application of the tool to a historical biogeography study on bivalves will be illustrated.

As required by Google Summer of Code and Biopython, the code is open access and is released under the Biopython License:
"http://www.biopython.org/DIST/LICENSE":http://www.biopython.org/DIST/LICENSE

The module is described, and a tutorial is presented, on the Biopython wiki:
http://biopython.org/wiki/BioGeography

The page contains links to the source hosted on Github; here is the direct link:
"http://github.com/nmatzke/biopython/tree/Geography":http://github.com/nmatzke/biopython/tree/Geograph

A non-standard approach to a market with boundedly rational consumers and strategic firms. Part I: A microfoundation for the evolution of sales

In our model, individual consumers follow simple behavioral decision rules based on imitation and habit as suggested in consumer research, social learning, and related fields. Demand can be viewed as the outcome of a population game whose revision protocol is determined by the consumers' behavioral rules. The consumer dynamics are then analyzed in order to explore the demand side and first implications for a strategic supply side.bounded rationality, social learning, population game, mean dynamic

Taking a shower in Youth Hostels: risks and delights of heterogeneity

Tuning one's shower in some hotels may turn into a challenging coordination game with imperfect information. The temperature sensitivity increases with the number of agents, making the problem possibly unlearnable. Because there is in practice a finite number of possible tap positions, identical agents are unlikely to reach even approximately their favorite water temperature. Heterogeneity allows some agents to reach much better temperatures, at the cost of higher risk.coordination, heterogeneity, adaptive learning, non-linear system, feedback

Product Pricing when Demand Follows a Rule of Thumb

We analyze the strategic behavior of firms when demand is determined by a rule of thumb behavior of consumers. We assume consumer dynamics where individual consumers follow simple behavioral decision rules governed by imitation and habit as suggested in consumer research. On this basis, we investigate monopoly and competition between firms, described via an open-loop differential game which in this setting is equivalent to but analytically more convenient than a closed-loop system. We derive a Nash equilibrium and examine the influence of advertising. We show for the monopoly case that a reduction of the space of all price paths in time to the space of time-constant prices is sensible since the latter in general contains Nash equilibria. We prove that the equilibrium price of the weakest active firm tends to marginal cost as the number of (non-identical) firms grows. Our model is consistent with observed market behavior such as product life cycles.bounded rationality, social learning, population game, differential game, product life cycle, monopoly, competition, pricing, advertising

Phase transition for a non-attractive infection process in heterogeneous environment

We consider a non-attractive three state contact process on $\mathbb Z$ and prove that there exists a regime of survival as well as a regime of extinction. In more detail, the process can be regarded as an infection process in a dynamic environment, where non-infected sites are either healthy or passive. Infected sites can recover only if they have a healthy site nearby, whereas non-infected sites may become infected only if there is no healthy and at least one infected site nearby. The transition probabilities are governed by a global parameter $q$: for large $q$, the infection dies out, and for small enough $q$, we observe its survival. The result is obtained by a coupling to a discrete time Markov chain, using its drift properties in the respective regimes

Generating functional analysis of a model economy with hetrogeneous adaptive consumers

This thesis examines the dynamics of a market with hetrogeneous and adaptive consumers who make their purchase decisions repeatedly. The main mathematical tool applied is the generating functional formalism. This tool allows for forming an average over the randomly assigned strategies of the consumers while simultaneously retaining all macroscopic information. The focus lies on the analysis of the stationary state of the ergodic region. First, the problem and the appropriate model are described, the generating functional analysis is then applied and finally the analytical results are interpreted and compared to numerical computer simulations