A 1200-year record of parrotfish teeth suggests centuries of overfishing in Belize.

Humans have utilized the Mesoamerican Reef for millennia but the effects of prehistorical and historical fishing on this ecosystem remain understudied. To assess long-term trends in reef fish abundance in the central Belizean portion, we used three reef matrix cores from this region to construct a record of parrotfish (Labridae) tooth abundance relative to the total number of all fish tooth subfossils. Parrotfish positively affect reef accretion rates and play a pivotal role in maintaining reefs in a coral-dominated state. Our study examined a 1200-year record across three coral cays: Elbow and Lagoon Cays and Bakers Rendezvous. Despite initial increases of fish tooth abundance at all three cays, declines were observed well before modern reef degradation. At Elbow Cay, an initial decline, likely due to Pre-Columbian Maya fishing, appears to be halted near the time of Spanish arrival. A subsequent decline begins at Elbow and Lagoon Cays likely due to Spanish colonization. The religious practices of the Catholic Spanish and the arrival of English privateers and logwooders likely increased fishing pressure. Bakers Rendezvous shows rapid accretion and parrotfish tooth accumulation as well as high tooth abundances, even as the other two cays show declines. Its sharper, more recent decline is likely the result of either the use of new, more southern fishing territories for Catholic Maya converts, the 1832 founding of Stann Creek Town by the Catholic Garifuna, or an interaction of the two. Our data suggest that the origins of reef degradation began hundreds of years before modern declines

Multicast Mobility in Mobile IP Version 6 (MIPv6) : Problem Statement and Brief Survey

Publisher PD

Asynchronous approach in the plane: A deterministic polynomial algorithm

In this paper we study the task of approach of two mobile agents having the same limited range of vision and moving asynchronously in the plane. This task consists in getting them in finite time within each other's range of vision. The agents execute the same deterministic algorithm and are assumed to have a compass showing the cardinal directions as well as a unit measure. On the other hand, they do not share any global coordinates system (like GPS), cannot communicate and have distinct labels. Each agent knows its label but does not know the label of the other agent or the initial position of the other agent relative to its own. The route of an agent is a sequence of segments that are subsequently traversed in order to achieve approach. For each agent, the computation of its route depends only on its algorithm and its label. An adversary chooses the initial positions of both agents in the plane and controls the way each of them moves along every segment of the routes, in particular by arbitrarily varying the speeds of the agents. A deterministic approach algorithm is a deterministic algorithm that always allows two agents with any distinct labels to solve the task of approach regardless of the choices and the behavior of the adversary. The cost of a complete execution of an approach algorithm is the length of both parts of route travelled by the agents until approach is completed. Let $\Delta$ and $l$ be the initial distance separating the agents and the length of the shortest label, respectively. Assuming that $\Delta$ and $l$ are unknown to both agents, does there exist a deterministic approach algorithm always working at a cost that is polynomial in $\Delta$ and $l$? In this paper, we provide a positive answer to the above question by designing such an algorithm

Noiseless coding for the magnetometer

Future unmanned space missions will continue to seek a full understanding of magnetic fields throughout the solar system. Severely constrained data rates during certain portions of these missions could limit the possible science return. This publication investigates the application of universal noiseless coding techniques to more efficiently represent magnetometer data without any loss in data integrity. Performance results indicated that compression factors of 2:1 to 6:1 can be expected. Feasibility for general deep space application was demonstrated by implementing a microprocessor breadboard coder/decoder using the Intel 8086 processor. The Comet Rendezvous Asteroid Flyby mission will incorporate these techniques in a buffer feedback, rate-controlled configuration. The characteristics of this system are discussed

New light on the ‘Drummer of Tedworth’: conflicting narratives of witchcraft in Restoration England

This paper presents a definitive text of hitherto little-known early documents concerning ‘The Drummer of Tedworth’, a poltergeist case that occurred in 1662-3 and became famous not least due to its promotion by Joseph Glanvill in his demonological work, Saducismus Triumphatus. On the basis of these and other sources, it is shown how responses to the events at Tedworth evolved from anxious piety on the part of their victim, John Mompesson, to confident apologetic by Glanvill, before they were further affected by the emergence of articulate scepticism about the case