Crowd-anticrowd theory of the Minority Game

The Minority Game is a simple yet highly non-trivial agent-based model for a complex adaptive system. Despite its importance, a quantitative explanation of the game's fluctuations which applies over the entire parameter range of interest has so far been lacking. We provide such a quantitative description based on the interplay between crowds of like-minded agents and their anti-correlated partners (anticrowds).Comment: Shortened version of cond-mat/0003486. Submitted for publicatio

Book Reviews

Reviews of the following books: Quarry and Kiln: The Story of Maine\u27s Lime Industry by Roger L. Grindle; Lisbon: the History of a Small Maine Town by Francis W. Plummer, Sr.; Bringing Broadway to Maine: The History of Lakewood (Theatre) Lakewood, Maine by John B. Obla

Enhanced winnings in a mixed-ability population playing a minority game

We study a mixed population of adaptive agents with small and large memories, competing in a minority game. If the agents are sufficiently adaptive, we find that the average winnings per agent can exceed that obtainable in the corresponding pure populations. In contrast to the pure population, the average success rate of the large-memory agents can be greater than 50 percent. The present results are not reproduced if the agents are fed a random history, thereby demonstrating the importance of memory in this system.Comment: 9 pages Latex + 2 figure

Space Station Centrifuge: A Requirement for Life Science Research

A centrifuge with the largest diameter that can be accommodated on Space Station Freedom is required to conduct life science research in the microgravity environment of space. (This was one of the findings of a group of life scientists convened at the University of California, Davis, by Ames Research Center.) The centrifuge will be used as a research tool to understand how gravity affects biological processes; to provide an on-orbit one-g control; and to assess the efficacy of using artificial gravity to counteract the deleterious biological effect of space flight. The rationale for the recommendation and examples of using ground-based centrifugation for animal and plant acceleration studies are presented. Included are four appendixes and an extensive bibliography of hypergravity studies

Multi-Agent Complex Systems and Many-Body Physics

Multi-agent complex systems comprising populations of decision-making particles, have many potential applications across the biological, informational and social sciences. We show that the time-averaged dynamics in such systems bear a striking resemblance to conventional many-body physics. For the specific example of the Minority Game, this analogy enables us to obtain analytic expressions which are in excellent agreement with numerical simulations.Comment: Accepted for publication in Europhysics Letter

Shedding light on El Farol

We mathematize El Farol bar problem and transform it into a workable model. In general, the average convergence to optimality at the collective level is trivial and does not even require any intelligence on the side of agents. Secondly, specializing to a particular ensemble of continuous strategies yields a model similar to the Minority Game. Statistical physics of disordered systems allows us to derive a complete understanding of the complex behavior of this model, on the basis of its phase diagram.Comment: 8 pages, 5 figure

Comparison of the Symbiotic Fauna of the Family Plethodontidae in the Ouachita Mountains of Western Arkansas

During the spring of 1985, 101 salamanders representing six host species (29 Plethodon ouachitae, 25 P. caddoensis, 6 P. fourchensis, 23 P. serratus, 13 Desmognathus brimleyorum, and 5 P. glutinosus glutinosus) were collected from six localities in three counties in Arkansas (Polk, Scott, and Montgomery) and examined for symbionts. With the exception of Hannemania dunni, all symbionts recovered from the first five species listed constitute new host records, and the endoparasitic fauna in all species establish new locality records. Examinations revealed one or more species of parasites in 82% of the hosts. Eight species of symbionts (3 nematode, 1 trematode, 1 cestode, 1 protozoan, 1 arthropod, and 1 cystacanth acanthocephalon) were recovered. Conclusions are based on the three host species examined in the largest numbers. Thelandros magnavulvularis and H. dunni were the most commonly occurring parasites, found in five and four host species respectively. Cepedietta michiganensis was restricted to P. ouachitae and Brachycoelium storeriae to P. caddoensis. Hannemania dunni was absent in P. serratus

Paleoeskimo Demography and Holocene Sea-level History, Gulf of Boothia, Arctic Canada

Surveys in six areas along the Gulf of Boothia produced large collections of radiocarbon samples from raised beaches that yield six new relative sea-level curves and information on Holocene bowhead whale ranges. In addition, on the lower beaches, we documented 482 Paleoeskimo dwelling features spanning about 3500 years (4200–800 14C years BP). Spatial densities of sites are only about half those reported by us from adjacent regions, but other attributes are remarkably similar. On the basis of feature elevation, corroborated by radiocarbon dates, Paleoeskimo occupation appears to have passed through a series of boom-and-bust cycles, the first being the most prominent. After the first peopling about 4200 BP, populations rose between about 3900 and 3600 BP to their all-time maximum, which was followed by a dramatic crash. Population recoveries after the initial crash were small and perhaps temporary. A final increase between 1900 (1500) and 800 14C years BP was followed by the disappearance of the Paleoeskimo. No compelling evidence yet points to the cause of the population declines; climate change and resource over-exploitation are equally plausible. The frequency distributions of dwelling sizes and numbers of dwellings per site closely resemble those in adjacent regions, suggesting similar social dynamics. Specifically, dispersed nuclear families or small extended families characterized Paleoeskimo settlement patterns for most of the year, but annual aggregations involved 100 or more people. The only significant architectural change coincides with the arrival of Late Dorset people bringing distinctive triangular midpassages and soapstone lamp supports.Des levés réalisés dans six régions situées le long du golfe de Boothia ont permis de recueillir de vastes collections d’échantillons au carbone 14 provenant de plages surélevées. Les résultats découlant de ces levés produisent six nouvelles résonances relatives du niveau de la mer de même que des renseignements sur le parcours des baleines de l’Holocène. Par ailleurs, dans le cas des plages inférieures, nous avons répertorié 482 caractéristiques d’habitations paléoesquimaudes s’étendant sur environ 3 500 ans (de 4200 à 800 14C années BP). Les densités spatiales des sites ne constituent environ que la moitié des densités qui nous avons repérées dans des régions adjacentes, mais les autres attributs sont remarquablement semblables. En ce qui a trait à l’élévation des caractéristiques, corroborée par la datation par le carbone 14, l’occupation paléoesquimaude semble avoir traversé une série de cycles d’expansion et de ralentissement, le premier de ces cycles étant le plus éminent. Après le premier peuplement vers 4200 BP, les populations se sont élevées entre 3900 et 3600 BP pour atteindre leur summum de tous les temps, ce qui a été suivi par un déclin dramatique. Les reprises de population après le déclin initial étaient minces, voire peut-être temporaires. Une dernière augmentation entre 1900 (1500) et 800 14C années BP a été suivie de la disparition des Paléoesquimaux. À ce jour, aucune preuve évidente ne nous laisse comprendre les déclins de population. Le changement climatique et la surexploitation des ressources sont des causes toutes aussi plausibles les unes que les autres. La distribution statistique relativement à la taille des habitations et au nombre d’habitations par site s’apparente de près à celle des régions adjacentes, ce qui laisse entrevoir une dynamique sociale semblable. Plus précisément, des familles nucléaires dispersées ou de petites familles étendues caractérisaient les modèles de peuplement des Paléoesquimaux pendant la plus grande partie de l’année, bien que les rassemblements annuels regroupaient une centaine de personnes ou plus. Le seul changement architectural important coïncide avec l’arrivée du peuple du Dorset tardif ayant mis en valeur des couloirs triangulaires distinctifs et des supports à lampes en saponite

Fertility and Infertility: Toward an Integrative Research Agenda

In this article, we show that social science research on fertility and infertility consists of largely separate research traditions, despite shared interest in pregnancies and births (or lack thereof). We describe four ways these two traditions differ: (1) publication trajectories and outlets, (2) fields of study and major theoretical frameworks, (3) degree of attention to the other topic, and (4) language and definitions used. We then discuss why future integration of these bodies of research would be beneficial, outline potential steps toward rapprochement, and provide common areas of dialogue that could facilitate and enrich these bodies of research. We offer a more holistic framework using the reproductive career as an extension of existing lifecourse approaches in both fertility and infertility research. We conclude with a brief empirical example and discussion of methodological issues for measuring and modeling reproductive careers

Surgical Sterilization, Regret, and Race: Contemporary Patterns

Surgical sterilization is a relatively permanent form of contraception that has been disproportionately used by Black, Hispanic, and Native American women in the United States in the past. We use a nationally representative sample of 4,609 women ages 25 to 45 to determine whether sterilization continues to be more common and consequential by race for reproductive-age women. Results indicate that Native American and Black women are more likely to be sterilized than non-Hispanic White women, and Hispanic and Native American women are more likely than non-Hispanic White women to report that their sterilization surgeries prevent them from conceiving children they want. Reasons for sterilization differ significantly by race. These findings suggest that stratified reproduction has not ended in the United States and that the patterns and consequences of sterilization continue to vary by race