Search results for "Multi"
showing 10 items of 17152 documents
Performance analysis of Alamouti-coded OFDM systems over spatio-temporally correlated underwater acoustic channels
2017
In this paper, we analyze the performance of Alamouti-coded orthogonal frequency division multiplexing (OFDM) systems over time-varying underwater acoustic (UWA) channels. A realistic UWA channel model has been considered, which can be correlated in either time or space or simultaneously in both domains. An exact analytical expression for the bit error probability (BEP) is necessary to analyze accurately the performance of Alamouti-coded OFDM systems over the spatio-temporally correlated UWA channel model. Hence, by using this UWA channel model, an expression has been derived for the BEP of Alamouti-coded OFDM systems assuming that the receiver knows perfectly the channel state information.…
2500 Years of European Climate Variability and Human Susceptibility
2011
Climate variations influenced the agricultural productivity, health risk, and conflict level of preindustrial societies. Discrimination between environmental and anthropogenic impacts on past civilizations, however, remains difficult because of the paucity of high-resolution paleoclimatic evidence. We present tree ring-based reconstructions of central European summer precipitation and temperature variability over the past 2500 years. Recent warming is unprecedented, but modern hydroclimatic variations may have at times been exceeded in magnitude and duration. Wet and warm summers occurred during periods of Roman and medieval prosperity. Increased climate variability from similar to 250 to 6…
Precise dating of the Middle-to-Upper Paleolithic transition in Murcia (Spain) supports late Neandertal persistence in Iberia
2017
Abstract The late persistence in Southern Iberia of a Neandertal-associated Middle Paleolithic is supported by the archeological stratigraphy and the radiocarbon and luminescence dating of three newly excavated localities in the Mula basin of Murcia (Spain). At Cueva Anton, Mousterian layer I-k can be no more than 37,100 years-old. At La Boja, the basal Aurignacian can be no less than 36,500 years-old. The regional Middle-to-Upper Paleolithic transition process is thereby bounded to the first half of the 37th millennium Before Present, in agreement with evidence from Andalusia, Gibraltar and Portugal. This chronology represents a lag of minimally 3000 years with the rest of Europe, where th…
The response of a shallow lake and its catchment to Late Glacial climate changes — A case study from eastern Poland
2015
In this study we investigate how climate fluctuation in the Late Glacial period influenced the development of a lake and its catchment located in the East European Plain. We analyzed the sediments of the lake for pollen, subfossil Cladocera, macrofossils and chemical composition. We aimed at disentangling: (1) the climate changes and their limno-ecological responses, (2) temperature dynamics with the use of Cladocera-based transfer function (MJT) and macrofossil-based reconstruction of mean minimum July temperature (MMJT), (3) timing of the response of different proxies to environmental changes. The results of multiproxy analyses explicitly suggest that the main driver for changes in aquati…
Symbolic use of marine shells and mineral pigments by Iberian Neandertals 115,000 years ago.
2018
U-Th dating of archaeological deposits of Cueva de los Aviones provides evidence for Neandertal symbolism 115,000 years ago.
Multi-archive summer temperature reconstruction for the European Alps, AD 1053–1996
2012
We present a multi-archive, multi-proxy summer temperature reconstruction for the European Alps covering the period AD 1053e1996 using tree-ring and lake sediment data. The new reconstruction is based on nine different calibration approaches and errors were estimated conservatively. Summer temperatures of the last millennium are characterised by two warm (AD 1053e1171 and 1823e1996) and two cold phases (AD 1172e1379 and 1573e1822). Highest pre-industrial summer temperatures of the 12th century were 0.3 � C warmer than the 20th century mean but 0.35 � C colder than proxy derived
Insights into the economic organization of the Phoenician homeland : a multidisciplinary investigation of the later Iron Age II and Persian period Ph…
2018
This paper details the results of a large-scale multi-disciplinary analysis of Iron Age pottery from a settlement in the core of the Phoenician homeland. The research presented is centred upon a large corpus of Phoenician carinated-shoulder amphorae (CSA) from the later Iron Age II and Persian period contexts at the coastal site of Tell el-Burak. Traditional typological investigations are combined with a focused archaeometric approach including a new quantitative method for the morphometric analysis of amphorae, thin-section petrography, geochemistry and organic residue analyses, aimed at gaining a more detailed understanding of the organization of the Phoenician economy. Despite gradual, b…
El yacimiento calcolítico de Karea en el contexto de las cuevas sepulcrales de Gipuzkoa (País Vasco)
2018
En el yacimiento arqueológico de Karea (Aia, Gipuzkoa), integrado por las cavidades contiguas de Karea-A y Karea-B, se recuperaron numerosos restos cerámicos y faunísticos (Karea-A) y vestigios de una inhumación calcolítica (Karea-B). El presente trabajo se ha vertebrado en dos ejes. En primer lugar, el estudio de ambos depósitos mediante diferentes disciplinas: (1) estudio antropológico; (2) estudio del ajuar, compuesto por restos cerámicos y faunísticos; (3) identificación antracológica de los restos leñosos recuperados en el depósito funerario y por último, (4) estudios isotópicos que nos han permitido obtener datos de la alimentación (δ13C y δ15N) y procedencia (87Sr/86Sr) del sujeto in…
Late Weichselian and Holocene record of the paleoenvironmental changes in a small river valley in Central Poland
2016
Abstract: The developmental history, from the Oldest Dryas to the Late Holocene, of a paleolake and mire located in a river valley in Central Poland was studied using high-resolution records of pollen, macrofossils, Cladocera, sedimentology, and geochemistry from a 14 C dated sediment core. We inferred temperature and water level dynamics using cladocerans and palynological and geochemical methods were employed to investigate natural fluvial activity, particularly for these elements that are difficult to find through sedimentological methods. Our research demonstrates how climate fluctuation in the Late Glacial and Holocene periods influenced the development of a paleolake and mire in a sma…
Causes and consequences of past and projected Scandinavian summer temperatures, 500-2100 AD
2011
Tree rings dominate millennium-long temperature reconstructions and many records originate from Scandinavia, an area for which the relative roles of external forcing and internal variation on climatic changes are, however, not yet fully understood. Here we compile 1,179 series of maximum latewood density measurements from 25 conifer sites in northern Scandinavia, establish a suite of 36 subset chronologies, and analyse their climate signal. A new reconstruction for the 1483–2006 period correlates at 0.80 with June–August temperatures back to 1860. Summer cooling during the early 17th century and peak warming in the 1930s translate into a decadal amplitude of 2.9°C, which agrees with existin…