Required and received SNRs in coded modulation

Coded modulation techniques aim at reducing the required signal-to-noise ratio (SNR) over the Gaussian channel with an average energy constraint; however, such techniques tend to degrade the received SNR. We studied the balance of required and received SNRs for a realistic system design

A multidisciplinary approach for dating human colonization of Pacific atolls

The timing of reef platform emergence and the detailed chronology of reef island development provides a powerful backdrop for constraining the earliest period possible for prehistoric human colonization of low-lying atolls. Since Pacific atolls consist of biogenetic sediments, we dated foraminifera sands composed of well-preserved shallow-water species that are reliable indicators of facies formation. From transect excavations across the largest islet of Utrōk Atoll (11°13'N, 169°50'E) and Maloelap Atoll (8°47'N, 171°05'E), Marshall Islands, we selected nine foraminifera dating samples and five charcoal samples from prehistoric ovens in well-defined cultural layers and charcoal from buried A horizons. We document that: 1) the largest islets of Utrōk and Maloelap atolls expanded towards the lagoon shore at a rate of ~70 m/kyr and ~200m/kyr, respectively; 2) foraminifera sands immediately below buried A horizons in the islet's "core" areas represents the timing of islet development at ~2750 and ~2400 cal BP, respectively; and 3) the oldest cultural dates (1850 and 1790 cal BP, ~900-600 years younger than islet development) indicates that occupation much older than 2000 cal BP is unlikely, which is supported by sea level falling from its high stands to the present levels around 2000 cal BP for the northwestern Pacific

Historical Ecology in Kiribati: Linking Past with Present.

v. ill. 23 cm.QuarterlyCompared with ‘‘high’’ islands, atolls and table reefs have received little attention from archaeologists focusing on historical ecology in Oceania. Limited archaeological investigations in the three archipelagoes composing the Republic of Kiribati (Gilbert, Phoenix, and Line Groups) reflect primarily culture historical reconstructions. Given the unique environmental challenges posed by coral islands, their potential for prehistoric ecological research should be recognized. By contrast, the last 50 years have witnessed a host of environmental studies, from agricultural improvements to sea-level rise and contemporary human impact on terrestrial and marine resources. In an attempt to better understand the influence of natural and human-induced processes in the more distant past, this paper explores several themes of relevance to coral islands in general. These include (1) natural and anthropogenic change on geomorphology and ecosystems, (2) anthropogenic impacts on faunal resources, (3) environmental evidence for human colonization, (4) interisland exchange networks and population mobility, and (5) social evolution