AMS dating of rock art in the Laura Region, Cape York Peninsula, Australia - protocols and results of recent research

The authors describe rock art dating research in Australia using the oxalate method While the array of dates obtained (which range from c. 1200 to c. 25000 BP) show a satisfactory correlation with other archaeological data, there are mismatches which suggest that some motifs were often imitated by later artists, and/or that the mineral accretions continued to form periodically, perhaps continuously, as a regional phenomenon over a long period of time.

High-precision TIMS U-series and AMS C-14 dating of a coral reef lagoon sediment core from southern South China Sea

Accurate dating of lagoon sediments has been a difficult problem, although lagoon profiles, usually with high deposition rates, have a great potential for high-resolution climate reconstruction. We report 26 high-precision TIMS U-series dates (on 25 coral branches) and five AMS C-14 dates (on foraminifera) for a 15.4-m long lagoon core from Yongshu Reef, Nansha area, southern South China Sea. All the dates are in the correct stratigraphical sequence, providing the best chronology so far reported for lagoon deposits. The results reveal a similar to 4000-a continuous depositional history, with sedimentation rates varying from 0.8 to 24.6 mm a(-1), with an average of 3.85 mm a(-1), which corresponds to an average net carbonate accumulation rate of similar to 2700 g CaCO3 m(-2) a(-1), significantly higher than the mean value (800 +/- 400 g CaCO3 m(-2) a(-1)) used for lagoons in general in previous studies of global carbonate budget. Episodes of accelerated depositions within the last 1000 years correlate well with strong storm events identified by U-series dates of storm-transported coral blocks in the area. However, in the longer term, the sedimentation rates during the past 1000 years were much higher than earlier on, probably due to more vigorous wave-reef interaction as a result of relative sea-level fall since 500 AD and expansion of reef flat area, supplying more sediments. The coral TIMS U-series ages and foraminifera AMS 14C dates reveal intriguing apparent radiocarbon reservoir ages (R) from 572 to 1052 years, which are much higher than global mean values of similar to 400 years. (c) 2006 Elsevier Ltd. All rights reserved.

O DIREITO É TORCIDO À PORTA PORQUE A JUSTIÇA SE ENCONTRA DEITADA POR TERRA: Um estudo sobre o direito e a justiça na profecia de Amós, a partir de Am 5,10-13

O trabalho que tem por título: O Direito é torcido à Porta porque a Justiça se encontra deitada por terra é um exercício exegético que tem por objeto a perícope Am 5,10-13. Na análise semântica dos seus principais vocábulos evidenciou-se uma realidade social, política e econômica paradoxal em Israel, sob o comando de Jeroboão II (787-747 a.C.), como resultado de uma expansão territorial e comercial, de vitórias militares e da organização de um Estado tributarista. Esse modelo de sociedade gerou um antagonismo social entre uma elite abastada que esbanjava luxo e ostentação, à custa do suor e da fome de uma população empobrecida, especialmente a classe camponesa, que trabalhava para sustentar as benesses do mundo urbano. É de dentro dessa realidade que ecoa o grito de Amós como denúncia a esse estado de coisas, como palavra de desgraça e condenação a toda sorte de desmandos praticados em Israel. Entre esses a falência do sistema judiciário, pela prática da exploração e corrupção por parte dos magistrados, de ricos comerciantes e latifundiários, desviando o pobre do seu direito de recorrer em sua defesa perante o tribunal. Em razão disso, Amós anuncia a ruína de Israel, com o Dia de Javé, que será um anti-Êxodo, e aponta uma exigência ético-religiosa como forma de reverter esse não futuro para Israel, que se traduz no compromisso de estabelecer à Porta o Direito e a Justiça.

DEBATE EM TORNO DA REDAÇÃO E COMPOSIÇÃO DO LIVRO DE AMÓS: PROPOSTAS FUNDAMENTAIS PARA A TEORIA DA CRIAÇÃO COLETIVA A PARTIR DE AMÓS 6,1-14

Esta pesquisa se dedica ao debate em torno da redação e composição do livro de Amós, e pretende, primeiramente, apresentar e criticar algumas hipóteses sobre as camadas literárias, que poderiam pertencer ao próprio profeta, e os acréscimos tardios. Como primeiro passo para uma abordagem do problema redacional, este estudo examina algumas contribuições de especialistas estrangeiros e de estudiosos brasileiros, e tenta fazer um julgamento crítico de suas hipóteses sobre a redação do livro de Amós. A questão do processo redacional do livro de Amós tem sido, na verdade, objeto de uma animada discussão entre muitos estudiosos. Em segundo lugar, a leitura diacrônica é complementada com o estudo sincrônico do livro, isto é, com o debate em torno da estrutura não só da composição em Amós 6,1-14, mas também do livro todo. Em terceiro lugar, a partir da avaliação do resultado da pesquisa e com a utilização do método histórico-crítico, a composição em Amós 6,1-14 é analisada como uma unidade literária de sentido. Para tal análise são, indubitavelmente, relevantes algumas considerações prévias sobre o gênero literário da lamentação, a denúncia profética da injustiça social e a instituição do banquete do marzeah. Em seqüência, esta tese analisa o fenômeno literário dos panfletos proféticos e da organização social, que poderia estar por detrás de sua autoria. Por isso, e levando em conta o desafio de novas propostas metodológicas, esta pesquisa visa dar uma contribuição específica ao estudo de Amós. Ela se empenha em demonstrar que, em relação a Amós 6,1-14, o leitor está diante de uma criação coletiva. De fato, a mencionada composição é o resultado não só da pregação oral do próprio profeta, mas também, em razão de sua forma compósita, das vozes proféticas de pessoas oprimidas, que, impulsionadas pelo Espírito, confirmaram a denúncia severa de Amós e até a completaram com suas próprias experiências e sofrimentos. Finalmente, um despretensioso excursus examina o livro de Amós em um contexto literário mais amplo, para dar uma visão geral do debate em torno do processo redacional do Livro dos Doze Profetas, particularmente a partir de sua perspectiva escatológica mediante a categoria teológica do Dia do Senhor.(AU)

Modelagem do consumo de energia de redes de sensores sem fio usando SystemC-AMS e stateflow

This work aims at modeling power consumption at the nodes of a Wireless Sensor Network (WSN). For doing so, a finite state machine was implemented by means of SystemC-AMS and Stateflow modeling and simulation tools. In order to achieve this goal, communication data in a WSN were collected. Based on the collected data, a simulation environment for power consumption characterization, which aimed at describing the network operation, was developed. Other than performing power consumption simulation, this environment also takes into account a discharging model as to analyze the battery charge level at any given moment. Such analysis result in a graph illustrating the battery voltage variations as well as its state of charge (SOC). Finally, a case study of the WSN power consumption aims to analyze the acquisition mode and network data communication. With this analysis, it is possible make adjustments in node-sensors to reduce the total power consumption of the network.

Single particle characterization using the soot particle aerosol mass spectrometer (SP-AMS)

Understanding the impact of atmospheric black carbon (BC) containing particles on human health and radiative forcing requires knowledge of the mixing state of BC, including the characteristics of the materials with which it is internally mixed. In this study, we demonstrate for the first time the capabilities of the Aerodyne Soot-Particle Aerosol Mass Spectrometer equipped with a light scattering module (LS-SP-AMS) to examine the mixing state of refractory BC (rBC) and other aerosol components in an urban environment (downtown Toronto). K-means clustering analysis was used to classify single particle mass spectra into chemically distinct groups. One resultant cluster is dominated by rBC mass spectral signals (C+1 to C+5) while the organic signals fall into a few major clusters, identified as hydrocarbon-like organic aerosol (HOA), oxygenated organic aerosol (OOA), and cooking emission organic aerosol (COA). A nearly external mixing is observed with small BC particles only thinly coated by HOA ( 28% by mass on average), while over 90% of the HOA-rich particles did not contain detectable amounts of rBC. Most of the particles classified into other inorganic and organic clusters were not significantly associated with BC. The single particle results also suggest that HOA and COA emitted from anthropogenic sources were likely major contributors to organic-rich particles with low to mid-range aerodynamic diameter (dva). The similar temporal profiles and mass spectral features of the organic clusters and the factors from a positive matrix factorization (PMF) analysis of the ensemble aerosol dataset validate the conventional interpretation of the PMF results.

(Table 1) AMS 14C dates from sediment cores RC12-10 and GYRE97-6PV-20

Proxy records from two piston cores in the Gulf of Mexico (GOM) provide a detailed (50-100 year resolution) record of climate variability over the last 14,000 years. Long-term (millennial-scale) trends and changes are related to the transition from glacial to interglacial conditions and movement of the average position of the Intertropical Convergence Zone (ITCZ) related to orbital forcing. The d18O of the surface-dwelling planktic foraminifer Globigerinoides ruber show negative excursions between 14 and 10.2 ka (radiocarbon years) that reflect influx of meltwater into the western GOM during melting of the Laurentide Ice Sheet. The relative abundance of the planktic foraminifer Globigerinoides sacculifer is related to transport of Caribbean water into the GOM. Maximum transport of Caribbean surface waters and moisture into the GOM associated with a northward migration of the average position of the ITCZ occurs between about 6.5 and 4.5 ka. In addition, abundance variations of G. sacculifer show century-scale variability throughout most of the Holocene. The GOM record is consistent with records from other areas, suggesting that century-scale variability is a pervasive feature of Holocene climate. The frequency of several cycles in the climate records is similar to cycles identified in proxy records of solar variability, indicating that at least some of the century-scale climate variability during the Holocene is due to external (solar) forcing.

(Table 2) Radiocarbon content and 14C AMS ages of planktonic foraminifera from sediment cores Louis_1900 and Louis_2023

North American freshwater runoff records have been used to support the case that climate flickers were caused by shutdowns of the ocean thermohaline circulation (THC) resulting from reversals of meltwater discharges. Inconsistencies in the documentation of these meltwater switches, however, continue to fuel the debate on the cause/s of the oscillatory nature of the deglacial climate. New oxygen and carbon isotope records from the northern Gulf of Mexico depict in exceptional detail the succession of meltwater floods and pauses through the southern routing during the interval 16 to 8.9 ka (14C years BP; ka, kiloannum). The records underscore the bimodal role played by the Gulf of Mexico as a destination of meltwater discharges from the receding Laurentide Ice Sheet. The evidence indicates that the Gulf of Mexico acted as the principal source of superfloods at 13.4, 12.6, and 11.9 ka that reached the North Atlantic and contributed significantly to density stratification, disruption of ocean ventilation, and cold reversals. Gulf of Mexico lapsed into a "relief valve" position in post-Younger Dryas time, when meltwater discharges were rerouted south at 9.9, 9.7, 9.4, and 9.1 ka, thus temporarily interrupting North Atlantic-bound freshwater discharges from Lake Agassiz. The history of meltwater events in the Gulf of Mexico contradicts the model that meltwater flow via the eastern outlets into the North Atlantic disrupted the ocean THC, causing cooling, while diversions to the Gulf of Mexico via the Mississippi River enhanced THC and warming.

AMS radiocarbon dates on ten monospecific samples of planktonic foraminifer Globigerinoides ruber of sediment core GeoB8509-2 (Table 1)

Aeolian and fluvial sediment transport to the Atlantic Ocean offshore Mauritania were reconstructed based on grain-size distributions of the carbonate-free silt fraction of three marine sediment records of Cap Timiris Canyon to monitor the climatic evolution of present-day arid north-western Africa. During the late Pleistocene, predominantly coarse-grained particles, which are interpreted as windborne dust, characterise glacial dry climate conditions with a low sea level and extended sand seas that reach onto the exposed continental shelf off Mauritania. Subsequent particle fining and the abrupt decrease in terrigenous supply are attributed to humid climate conditions and dune stabilisation on the adjacent African continent with the onset of the Holocene humid period. Indications for an ancient drainage system, which was discharging fluvial mud offshore via Cap Timiris Canyon, are provided by the finest end member for early to mid Holocene times. However, in comparison to the Senegal and Niger River further south, the river system connecting Cap Timiris Canyon with the Mauritanian hinterland was starved during the late Holocene and is non-discharging under present-day arid climate conditions.

(Table 1) AMS-14C ages determined in pairs of spreiten and directly adjacent host sediment of cores M39029-4 and M29039-8

he downward transport of surface sediment deep into the sediment column by the Zoophycos-producing animal leads not only to large age differences between the Zoophycos structure and surrounding host sediment but also to large differences in age between different foraminifer species found inside the trace fossil. In the late Quaternary material from the southwestern Portuguese continental slope examined in this study, age differences of up to 2590 years were observed between the planktic foraminifer species Globigerinoides ruber and Globigerina bulloides. These differences are caused by the mixing of surface and host material with different abundances of the two species. If there are differences in the abundance of the two species at the surface and/or in the host sediment, plenty of relatively young foraminifers may be mixed with few relatively old ones, or vice versa. The age differences between species caused by the combination of deep-reaching bioturbation by the Zoophycos producer and abundance variations may be considerably larger than the age differences caused by the homogenizing bioturbation in the mixed layer.