Paleoclimatic and paleoenvironmental framework of FLK North archaeological site, Olduvai Gorge, Tanzania

International audienceThe multi component FLK North archaeological site was discovered over 50 years ago, and its interpretation has been highly controversial since. Explanations of the dense bone and stone tool accumulation range from a site on a featureless lake margin that is dominantly anthropogenic in origin to a site near a freshwater wetland that is dominated by carnivore activity (e.g. felids and hyenas). FLK North occurs stratigraphically between the Ng'eju Tuff (1.818 ± 0.006 Ma) and Tuff IF (1.803 ± 0.002 Ma), and is composed of 9 distinct levels. Analysis of newly recovered fossil bones and artifacts has shown that the bones of large animals are largely the product of felid hunting and feeding behavior, followed by hyena gnawing and breakage of some bones. The expanded sample of felid prey remains is significant for understanding the contrasts between the mortality profiles of fossil assemblages produced by carnivores and those produced by hominins. Geologic mapping in the environs of the site has revealed rich sedimentological and paleoecological records and a thin, but persistent tuff (here named Kidogo Tuff) that is ∼1.5 m below Tuff IF. Electron microprobe analyses of the tuff mineralogy revealed a unique geochemical fingerprint that permits its use for correlation of widely separated outcrops and facilitates the high resolution reconstruction of the landscape at the time of site formation. The 9 archaeological levels comprise a relatively continuous record through a Milankovitch precession cycle (dry-wet-dry). As the lake receded into the central basin during the dry part of the cycle, surface water supplies dwindled and groundwater-fed springs and wetlands became the dominant freshwater supply. The FLK North archaeological record essentially ended when level 1 was covered with 0.4 m of Tuff IF in a violent volcanic eruption of nearby Mt. Olmoti. However, the overlying Bed II sediments contain scattered archaeological material and a freshwater carbonate deposit that is similar to those found associated with other Bed II archaeological sites, e.g. VEK, HWK and HWKE. The recognition of the ecological association of springs, wetlands and archaeological remains is a powerful predictive tool for locating new archaeological sites in this region that is known for hominin remains

Improving the performance of remote sensing models for capturing intra- and inter-annual variations in daily GPP: An analysis using global FLUXNET tower data

Accurate and reliable estimates of gross primary productivity (GPP) are required for monitoring the globalcarbon cycle at different spatial and temporal scales. Because GPP displays high spatial and temporal vari-ation, remote sensing plays a major role in producing gridded estimates of GPP across spatiotemporalscales. In this context, understanding the strengths and weaknesses of remote sensing-based models ofGPP and improving their performance is a key contemporary scientific activity. We used measurementsfrom 157 research sites (∼470 site-years) in the FLUXNET “La Thuile” data and compared the skills of11 different remote sensing models in capturing intra- and inter-annual variations in daily GPP in sevendifferent biomes. Results show that the models were able to capture significant intra-annual variationin GPP (Index of Agreement = 0.4–0.80) in all biomes. However, the models’ ability to track inter-annualvariation in daily GPP was significantly weaker (IoA < 0.45). We examined whether the inclusion of differ-ent mechanisms that are missing in the models could improve their predictive power. The mechanismsincluded the effect of sub-daily variation in environmental variables on daily GPP, factoring-in differentialrates of GPP conversion efficiency for direct and diffuse incident radiation, lagged effects of environmen-tal variables, better representation of soil-moisture dynamics, and allowing spatial variation in modelparameters. Our analyses suggest that the next generation remote sensing models need better represen-tation of soil-moisture, but other mechanisms that have been found to influence GPP in site-level studiesmay not have significant bearing on model performance at continental and global scales.JRC.E.1-Disaster Risk Managemen

ADHD-like symptoms and attachment in internationally adopted children.

Internationally adopted children seem to be more likely to show ADHD-like symptoms than non-adopted children. The aims of this study were to explore the existence of ADHD-like symptoms and/or diagnosis in a sample of internationally adopted children depending on their country of origin and to describe the links that may exist between the display of these symptoms and observed narrative-based attachment patterns. A Catalan sample of 58 adopted children aged 7-8 (24 from Eastern Europe, 23 from China, and 11 from Ethiopia) was assessed with the Behavioral Assessment System for Children to identify ADHD-like symptoms, and the Friends and Family Interview to identify children's' attachment patterns. Results indicated that children adopted from Eastern Europe showed a trend toward more hyperactivity and significantly more attention problems than girls adopted from China. Children with a secure attachment showed significantly less attention problems and a trend toward less hyperactivity. More studies focusing on the etiology and treatment of these symptoms in adopted children are needed

First low-frequency Einstein@Home all-sky search for continuous gravitational waves in Advanced LIGO data

International audienceWe report results of a deep all-sky search for periodic gravitational waves from isolated neutron stars in data from the first Advanced LIGO observing run. This search investigates the low frequency range of Advanced LIGO data, between 20 and 100 Hz, much of which was not explored in initial LIGO. The search was made possible by the computing power provided by the volunteers of the Einstein@Home project. We find no significant signal candidate and set the most stringent upper limits to date on the amplitude of gravitational wave signals from the target population, corresponding to a sensitivity depth of 48.7  [1/Hz]. At the frequency of best strain sensitivity, near 100 Hz, we set 90% confidence upper limits of 1.8×10-25. At the low end of our frequency range, 20 Hz, we achieve upper limits of 3.9×10-24. At 55 Hz we can exclude sources with ellipticities greater than 10-5 within 100 pc of Earth with fiducial value of the principal moment of inertia of 1038  kg m2

First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data

International audienceSpinning neutron stars asymmetric with respect to their rotation axis are potential sources of continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a fully coherent search, based on matched filtering, which uses the position and rotational parameters obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signal-to-noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have been developed, allowing a fully coherent search for gravitational waves from known pulsars over a fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of 11 pulsars using data from Advanced LIGO’s first observing run. Although we have found several initial outliers, further studies show no significant evidence for the presence of a gravitational wave signal. Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for the first time. For an additional 3 targets, the median upper limit across the search bands is below the spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried out so far

Search for intermediate mass black hole binaries in the first observing run of Advanced LIGO

International audienceDuring their first observational run, the two Advanced LIGO detectors attained an unprecedented sensitivity, resulting in the first direct detections of gravitational-wave signals produced by stellar-mass binary black hole systems. This paper reports on an all-sky search for gravitational waves (GWs) from merging intermediate mass black hole binaries (IMBHBs). The combined results from two independent search techniques were used in this study: the first employs a matched-filter algorithm that uses a bank of filters covering the GW signal parameter space, while the second is a generic search for GW transients (bursts). No GWs from IMBHBs were detected; therefore, we constrain the rate of several classes of IMBHB mergers. The most stringent limit is obtained for black holes of individual mass 100  M⊙, with spins aligned with the binary orbital angular momentum. For such systems, the merger rate is constrained to be less than 0.93  Gpc−3 yr−1 in comoving units at the 90% confidence level, an improvement of nearly 2 orders of magnitude over previous upper limits