In the Hamadryas baboon, males are substantially larger than females. A troop of baboons is subdivided into a number of ‘one-male groups’, consisting of one adult male and one or more females with their young. The male prevents any of ‘his’ females from moving too far from him. Kummer (1971) performed the following experiment. Two males, A and B, previously unknown to each other, were placed in a large enclosure. Male A was free to move about the enclosure, but male B was shut in a small cage, from which he could observe A but not interfere. A female, unknown to both males, was then placed in the enclosure. Within 20 minutes male A had persuaded the female to accept his ownership. Male B was then released into the open enclosure. Instead of challenging male A , B avoided any contact, accepting A’s ownership.

Evolution and the Theory of Games

where A represents the magnetic vector potential, is an integral of the hydromagnetic equations. This -integral made it possible to formulate a variational principle for the force-free magnetic fields. The integral expresses the fact that motions cannot transform a given field in an entirely arbitrary different field, if the conductivity of the medium isconsidered infinite. In this paper we shall show that the full set of hydromagnetic equations admit five more integrals, besides the energy integral, if dissipative processes are absent. These integrals, as we shall presently verify, are I2 =fbHvdV, (2)

Proceedings of the National Academy of Sciences

There are two kinds of tutorial articles: those that provide a primer on an established topic and those that let us in on the ground floor of something of emerging importance. The first type of tutorial can have a noted expert who has been gracious (and brave) enough to write a field guide about a particular topic. The other sort of tutorial typically involves researchers who have each been laboring on a topic for some years. Both sorts of tutorial articles are very much desired. But we, as an editorial board for both Systems and Transactions, know that there has been no logical place for them in the AESS until this series was started several years ago. With these tutorials, we hope to continue to give them a home, a welcome, and provide a service to our membership. We do not intend to publish tutorials on a regular basis, but we hope to deliver them once or twice per year. We need and welcome good, useful tutorial articles (both kinds) in relevant AESS areas. If you, the reader, can offer a topic of interest and an author to write about it, please contact us. Self-nominations are welcome, and even more ideal is a suggestion of an article that the editor(s) can solicit. All articles will be reviewed in detail. Criteria on which they will be judged include their clarity of presentation, relevance, and likely audience, and, of course, their correctness and scientific merit. As to the mathematical level, the articles in this issue are a good guide: in each case the author has striven to explain complicated topics in simple-well, tutorial-terms. There should be no (or very little) novel material: the home for archival science is the Transactions Magazine, and submissions that need to be properly peer reviewed would be rerouted there. Likewise, articles that are interesting and descriptive, but lack significant tutorial content, ought more properly be submitted to the Systems Magazine.

What is a tutorial

ReviewFeature ReviewHuman cooperation

ECOLOGY/EVOLUTION: Phenotypic Plasticity

http://psystems.disco.unimib.it/download/snpasyP.pdf

Asynchronous spiking neural P systems

Microbial communities are increasingly utilised in biotechnology. Efficiency and productivity in many of these applications depends on the presence of cooperative interactions between members of the community. Two key processes underlying these interactions are the production of public goods and metabolic crossfeeding, which can be understood in the general framework of ecological and evolutionary (eco-evo) dynamics. In this review we illustrate the relevance of cooperative interactions in microbial biotechnological processes, discuss their mechanistic origins, and analyse their evolutionary resilience. Cooperative behaviours can be damaged by the emergence of ‘cheating’ cells that benefit from the cooperative interactions but do not contribute to them. Despite this, cooperative interactions can be stabilized by spatial segregation, by the presence of feedbacks between the evolutionary dynamics and the ecology of the community, by the role of regulatory systems coupled to the environmental conditions and by the action of horizontal gene transfer. Cooperative interactions enrich microbial communities with a higher degree of robustness against environmental stress and can facilitate the evolution of more complex traits. Therefore, the evolutionary resilience of microbial communities and their ability to constraint detrimental mutants should be considered in order to design robust biotechnological applications.

Cooperation in microbial communities and their biotechnological applications.

We propose a new class of P systems that use simple evolution rules (classical evolution rules without communication targets) and symport/antiport rules (for communication).

Evolution-communication P systems

We introduce a class of P systems called timed P systems where to each rule is associated an integer that represents the time needed by the rule (reaction) to be entirely executed. The idea comes from cell biology where chemical reactions take certain times to be executed. In this work we are interested in a special class of P systems, called time-free, working always in the same way (i.e., always producing the same result) independently from the values associated to the execution time of their rules.

Later we introduce a generalization of time-free P systems, namely clock-free P systems, where a time of execution is associated directly to each single application of the rules (in this case, different applications, even of the same rule, may take a different time to be executed). Several results are presented together with open problems and research proposals.

Time–independent p systems

https://scholar.princeton.edu/sites/default/files/Cavaliere_JTB_2012_0.pdf

Matteo Cavaliere

Papers

Asynchronous spiking neural P systems

Cooperation in microbial communities and their biotechnological applications.

Evolution-communication P systems

Time–independent p systems

Prosperity is associated with instability in dynamical networks.