Vegetation and climate changes in the forest of Campinas, São Paulo State, Brazil, during the last 25,000 cal yr BP

A paleoenvironmental reconstruction was performed in a Riparian Forest near Campinas to improve knowledge of paleoclimate and paleoenvironment in the State of São Paulo, Brazil. A sediment core of 182 cm depth was collected in a swamp located within a Cerrado/Seasonal Semi-deciduous ecotone forest. Te chronological frame is given by eight radiocarbon dating methods. Pollen and stable isotope analyses (d 13C and d 15N) were performed all along the core. Modern pollen rain is based on fve surface samples collected along the Riparian Forest. Results show a sequence of changes in vegetation and climate between 25 and 13 cal kyr before present (BP), and from 4 cal kyr BP to the present time, with a hiatus between 11 and 4 kyr cal BP. Drier climatic conditions characterized the late Pleistocene and early Holocene, although they had moisture peaks able to maintain an open forest. Te Riparian Forest became fully installed from 4 cal kyr BP onward. Our results are in agreement with other regional studies and contribute to build a regional frame for past climatic conditions at the latitude of São Paulo.493CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPSem informaçãoSem informação2010/16507-

The benefits of mind wandering on a naturalistic prospective memory task

Mind wandering (MW) occurs when our attention spontaneously shifts from the task at hand to inner thoughts. MW is often future-oriented and may help people remember to carry out their planned actions (Prospective Memory, PM). Past-oriented MW might also play a critical role in boosting PM performance. Sixty participants learned 24 PM items and recalled them during an immersive virtual walk in a town. The items were divided into event-based-EB and time-based-TB. During the PM retention phase, participants were randomly assigned to a high or a low cognitive load condition, in order to manipulate MW frequency. Some PM items were encoded before this MW manipulation (pre-PM) and some during the virtual walk (post-PM). A high MW frequency was linked with better global PM performances. Spontaneous past-oriented MW predicted better pre-EB retrospective PM retrieval, while spontaneous future-oriented MW predicted better Pre-EB prospective PM retrieval. Voluntary future-oriented MW predicted better post-EB retrospective retrieval. We highlighted, for the first time, a differential impact of spontaneous MW content depending on the PM component (retrospective or prospective). Past-oriented MW is crucial for (re)consolidating PM intentions, and episodic future thinking MW for the execution of PM intentions. We discuss the twofold functional role of MW, namely, to consolidate an already programmed intention and to plan future actions

Last Glacial Maximum in an Andean cloud forest environment (Eastern Cordillera, Bolivia): Comment and Reply

Whether the climate of tropical South America during the Last Glacial Maximum (LGM) was colder and drier or colder and wetter than present day has been widely debated. It is accepted, however, that the LGM in tropical South America was 2–9 °C colder than today (e.g., Betts and Ridgway, 1992; Bush et al., 2001). Without debating the merits of the following choices, if we assume a lapse rate in the LGM similar to the modern one of ~0.6 °C·100 m−1, then an intermediate cooling of 5 °C would lower the boundary between montane cloud forest and the overlying puna grasslands by ~800 or 900 m. Palynologists on both sides of the wet/dry debate have come to similar conclusions about forest-boundary lowering due to temperature decrease (reviewed by Flenley, 1998). In the Eastern Cordillera of Bolivia the modern puna–cloud forest boundary lies ~3400 m above sea level (masl). Ignoring any other environmental changes, LGM cooling would have lowered this boundary to 2500 or 2600 masl

Geochemical and mineralogical signature of fault zones in Archean basement rocks: characterizing a multi-episodic history of fluid-rock interactions

East of the Paleoproterozoic Thelon basin (Nunavut, Canada), unconformity-related uranium deposits of the Kiggavik area, explored by AREVA, are hosted within Archean basement rocks (mainly gneisses and various magmatic intrusives). The study focuses on the Contact prospect, located along the NE-trending Andrew Lake fault and hosted within Archean granitic gneiss. There, the fracture network evolved in a brittle style from ca. 1830 Ma to ca. 1300 Ma for the main fracturing events. The successive fracturing events were associated with circulation of various fluids that interacted with host rocks and fault rocks and caused alteration of the protolith while precipitating new minerals, thus changing the elemental signature of the rock and giving each event a characteristic geochemical signature. AREVA possesses a vast dataset of systematic geochemical analyses (1519 samples in the dataset of the Contact prospect) which, along with newly conducted mineral characterization (microscopy, SEM, microprobe) and fluid inclusions study (microthermometry, Raman spectroscopy, LA-ICP MS) allowed characterizing the geochemical signature of selected fault zones, hence of the fluids that traveled through them at the time of each fracturing event. Four major fracturing events were geochemically characterized: one occurring at ca. 1750 Ma before the emplacement of the Paleoproterozoic Thelon basin infill (1667-1540 Ma), and three occurring after (between 1540 and 1267 Ma). The first main fracturing event is characterized by circulation of Si-rich fluids likely of igneous origin that silicified the Andrew Lake fault system. Vapor-only fluid inclusions displaying low-salinity and high entrapment temperature are representative of the mosaic quartz breccia that sealed fault zones during this event. The fracturing events and associated fluid circulations occurring after this silicifying event were compartmentalized by a large quartz breccia zone. Fault zones of the second fracturing event are relatively narrow ( to 50m) with moderate enrichment in the same elements, except for Fe, Mo, V and Se; they also display a higher content in non-mobile elements (Al and Ti) as a result of the loss of mobile elements during argillization. The fluids that circulated during these two fracturing events were oxidizing, sodic-calcic basinal brines of low temperatures (∼200 ◦C), enriched in uranium. The fourth fracturing event is characterized by fault zones that drove reduced, likely acidic and hot fluids (∼300 ◦C), that caused complete destabilization of iron oxides and also illitization of the host rock. This kind of analysis sheds light on the complexity of the fluid circulation events that may have occurred in impermeable basement rocks, and provides a powerful tool to decipher fluid-fault interactions and to potentially distinguish successive fault zones in cores by their geochemical signature

Deciphering the complex evolution of a polyphase fault/fracture network and its control on fluid circulation and ore deposition through macro- to micro-scale observations

In the Kiggavik area (Nunavut, Canada), uranium mineralization is hosted in outcropping metamorphosed Archean to Paleoproterozoic basement rocks that were likely covered by the nearby Paleoproterozoic sandstones of the Thelon basin infill (1667-1540 Ma). The uranium mineralization is controlled by faults and fractures which developed during a long-lasting polyphase brittle tectonic history spanning from ca. 1850 Ma (after the Thelon and Trans-Hudsonian orogenies) to ca. 1270 Ma (before emplacement of MacKenzie dikes) for the main fracturing events

Sporormiella as a tool for detecting the presence of large herbivores in the Neotropics

The reliability of using the abundance of Sporormiella spores as a proxy for the presence and abundance of megaherbivores was tested in southern Brazil. Mud-water interface samples from nine lakes, in which cattle-use was categorized as high, medium, or low, were assayed for Sporormiella representation. The sampling design allowed an analysis of both the influence of the number of animals using the shoreline and the distance of the sampling site from the nearest shoreline. Sporormiella was found to be a reliable proxy for the presence of large livestock. The concentration and abundance of spores declined from the edge of the lake toward the center, with the strongest response being in sites with high livestock use. Consistent with prior studies in temperate regions, we find that Sporormiella spores are a useful proxy to study the extinction of Pleistocene megafauna or the arrival of European livestock in Neotropical landscapes

Model-Based Filtering of Combinatorial Test Suites

International audienceTobias is a combinatorial test generation tool which can efficiently generate a large number of test cases by unfolding a test pattern and computing all combinations of parameters. In this paper, we first propose a model-based testing approach where Tobias test cases are first run on an executable UML/OCL specification. This animation of test cases on a model allows to filter out invalid test sequences produced by blind enumeration, typically the ones which violate the pre-conditions of operations, and to provide an oracle for the valid ones. We then introduce recent extensions of the Tobias tool which support an incremental unfolding and filtering process, and its associated toolset. This allows to address explosive test patterns featuring a large number of invalid test cases, and only a small number of valid ones. For instance, these new constructs could mandate test cases to satisfy a given predicate at some point or to follow a given behavior. The early detection of invalid test cases improves the calculation time of the whole generation and execution process, and helps fighting combinatorial explosion

Regulators of cell movement during development and regeneration in Drosophila

Cell migration is a fundamental cell biological process essential both for normal development and for tissue regeneration after damage. Cells can migrate individually or as a collective. To better understand the genetic requirements for collective migration, we expressed RNA interference (RNAi) against 30 genes in the Drosophila embryonic salivary gland cells that are known to migrate collectively. The genes were selected based on their effect on cell and membrane morphology, cytoskeleton and cell adhesion in cell culture-based screens or in Drosophila tissues other than salivary glands. Of these, eight disrupted salivary gland migration, targeting: Rac2, Rab35 and Rab40 GTPases, MAP kinase-activated kinase-2 (MAPk-AK2), RdgA diacylglycerol kinase, Cdk9, the PDSW subunit of NADH dehydrogenase (ND-PDSW) and actin regulator Enabled (Ena). The same RNAi lines were used to determine their effect during regeneration of X-ray-damaged larval wing discs. Cells translocate during this process, but it remained unknown whether they do so by directed cell divisions, by cell migration or both. We found that RNAi targeting Rac2, MAPk-AK2 and RdgA disrupted cell translocation during wing disc regeneration, but RNAi against Ena and ND-PDSW had little effect. We conclude that, in Drosophila, cell movements in development and regeneration have common as well as distinct genetic requirements