A global climate niche for giant trees

<p>Rainforests are among the most charismatic as well as the most endangered ecosystems of the world. However, although the effects of climate change on tropical forests resilience is a focus of intense research, the conditions for their equally impressive temperate counterparts remain poorly understood, and it remains unclear whether tropical and temperate rainforests have fundamental similarities or not. Here we use new global data from high precision laser altimetry equipment on satellites to reveal for the first time that across climate zones ‘giant forests’ are a distinct and universal phenomenon, reflected in a separate mode of canopy height (~40 m) worldwide. Occurrence of these giant forests (cutoff height &gt; 25 m) is negatively correlated with variability in rainfall and temperature. We also demonstrate that their distribution is sharply limited to situations with a mean annual precipitation above a threshold of 1,500 mm that is surprisingly universal across tropical and temperate climates. The total area with such precipitation levels is projected to increase by ~4 million km² globally. Our results thus imply that strategic management could in principle facilitate the expansion of giant forests, securing critically endangered biodiversity as well as carbon storage in selected regions.</p

Voyaging and Interaction in Ancient East Polynesia

The origins of East Polynesian culture are traced to a regional homeland that was centered on the Society Islands but which also included neighboring archipelagoes. Archaeological evidence suggests a fall-off through time in the frequency of opensea voyaging within this homeland, with marked declines in voyaging and interaction after A.D. 1450. A range of social and environmental factors may have contributed to these declines. The regional distribution of terrestrial resources is significant because the smallest islands often suffered the most acute consequences of human-induced environmental change. Tahiti, in the Society Islands, is unique in terms of the unparalleled scale of its resource base and its high degree of voyaging accessibility. If Tahiti and the Societies played the role of a regional hub in early interaction spheres, developments in Tahiti may have influenced inhabitants of the outer archipelagoes. Specifically, if circumstances restricted the flow of timber and canoes from the Societies to outlying archipelagoes, and this coincided with the depletion of forest reserves on the smaller outlying islands, these developments could help explain the contraction of early central East Polynesian interaction spheres. It is likely that voyaging patterns in the Marquesas and the Pitcairn Islands, comparatively isolated archipelagoes, were little affected by internal developments in the Societies. KEYWORDS: East Polynesia, ancient voyaging, interaction spheres

Geological Sourcing of Volcanic Stone Adzes from Neolithic Sites in Southeast China

This study uses XRF (X-ray fluorescence) and ICP-MS (inductively coupled plasma mass spectrometry) analyses to determine the chemical composition of raw material used in stone tool production. The goal is to identify where stone adzes, which are common in Neolithic sites on the coast of Mainland China, were produced and if they were transported from the production areas to other places. Our study focuses on adzes from three Neolithic sites located on the Fujian coast of Mainland China, opposite Taiwan. The sites date to between 6500 and 3500 B.P. All of the adzes we sampled are made of volcanic rock. A diverse selection of raw materials, including basalts, andesites, and dacites, was used in manufacturing the adzes, indicating that they are made of rock deriving from many different geological formations. None of the adzes have identical chemical signatures. There is no evidence of specialized centers for adze production. Some of the adzes were probably produced locally, while others were obtained through exchange. This project sets the stage for future research to trace the development and the extent of southeast China Neolithic exchange networks. KEYWORDS: China, Neolithic, stone tools, adzes, production techniques, archaeometry, exchange

A Java implementation of the Rochester Software Transactional Memory Library

Thesis (B.S.)--University of Rochester. Dept. of Computer Science, 2008.Recent advances in chip design have necessitated the development of a new programming model to simplify multithreaded programming. Transactional Memory (TM) replaces lock based thread synchronization with a new interface that approximates global lock semantics. In this paper an implementation of RSTM in Java is compared and contrasted with the C++ RSTM implementation as well as Sun’s own DSTM2 library implementation. The version of RSTM Java evaluated in this paper provides Sun’s DSTM2 API. Additional overhead introduced into the RSTM library by running it in Java with the Sun DSTM2 API is also discussed

Marquesan prehistory and the origins of East Polynesian culture

Abstract . Temporal relationships are established among artifact assemblages from four archaeological sites on different islands in the Marquesas. One of four models of early East Polynesian prehistory may best explain the data available from these sites. The Marquesan archaeological data are analyzed in terms of the four models. These data, as well as those from sites elsewhere in East Polynesia, favor a model of Interaction and cultural continuity. This model suggests that long distance two-way voyaging linked distant archipelagoes during early East Polynesian prehistory, creating a regional homeland with cultural similarities maintained by intercommunication.Rolett Barry V. Marquesan prehistory and the origins of East Polynesian culture. In: Journal de la Société des océanistes, 96, 1993-1. pp. 29-47