Romanian Academy

About: Romanian Academy is a archive organization based out in Bucharest, Romania. It is known for research contribution in the topics: Population & Nonlinear system. The organization has 3662 authors who have published 10491 publications receiving 146447 citations. The organization is also known as: Academia Română & Societatea Literară Română.

Variations in color and reflectance on the surface of asteroid (101955) Bennu

Abstract: Visible-wavelength color and reflectance provide information about the geologic history of planetary surfaces. We present multispectral images (0.44 to 0.89 microns) of near-Earth asteroid (101955) Bennu. The surface has variable colors overlain on a moderately blue global terrain. Two primary boulder types are distinguishable by their reflectance and texture. Space weathering of Bennu surface materials does not simply progress from red to blue (or vice versa). Instead, freshly exposed, redder surfaces initially brighten in the near-ultraviolet (become bluer at shorter wavelengths), then brighten in the visible to near-infrared, leading to Bennu’s moderately blue average color. Craters indicate that the timescale of these color changes is ~105 years. We attribute the reflectance and color variation to a combination of primordial heterogeneity and varying exposure ages.

Origin of the forest steppe and exceptional grassland diversity in Transylvania (central-eastern Europe)

Abstract: Aim The forest steppe of the Transylvanian Plain is a landscape of exceptionally diverse steppe-like and semi-natural grasslands. Is this vegetation a remnant of a once continuous temperate forest extensively cleared by humans, or has the area, since the last glacial, always been a forest steppe? Understanding the processes that drive temperate grassland formation is important because effective management of this biome is critical to the conservation of the European cultural landscape. Location Lake Stiucii, north-western Romania, central-eastern Europe. Methods We analysed multi-proxy variables(pollen, coprophilous fungi,plant macroremains, macrocharcoal) from a 55,000 year discontinuous sequence (c. 55,000–35,000; 13,000–0 cal. yr bp), integrating models of pollenbased vegetation cover, biome reconstruction, global atmospheric simulations and archaeological records. Results Needleleaf woodland occurred during glacial Marine Isotope Stage (MIS) 3, but contracted at the end of this period. Forest coverage of c. 55% (early Holocene) and 65% (mid-Holocene) prevailed through the Holocene, but Bronze Age humans extensively cleared forests after 3700 cal. yr bp. Forest coverage was most widespread between 8600 and 3700 cal. yr bp, whereas grasses, steppe and xerothermic forbs were most extensive between 11,700 and 8600 cal. yr bp and during the last 3700 cal. yr bp. Cerealia pollen indicate the presence of arable agriculture by c. 7000 cal. yr bp. Main conclusions We have provided the first unequivocal evidence for needleleaf woodland during glacial MIS 3 in this region. Extensive forests prevailed prior to 3700 cal. yr bp, challenging the hypothesis that the Transylvanian lowlands were never wooded following the last glaciation. However, these forests were never fully closed either, reflecting dry growing season conditions, recurrent fires and anthropogenic impacts, which have favoured grassland persistence throughout the Holocene. The longevity of natural and semi-natural grasslands in the region may explain their current exceptional biodiversity. This longer-term perspective implies that future climatic warming and associated fire will maintain these grasslands.

The Campanian Ignimbrite eruption: new data on volcanic ash dispersal and its potential impact on human evolution.

Abstract: The Campanian Ignimbrite (CI) volcanic eruption was the most explosive in Europe in the last 200,000 years. The event coincided with the onset of an extremely cold climatic phase known as Heinrich Event 4 (HE4) approximately 40,000 years ago. Their combined effect may have exacerbated the severity of the climate through positive feedbacks across Europe and possibly globally. The CI event is of particular interest not only to investigate the role of volcanism on climate forcing and palaeoenvironments, but also because its timing coincides with the arrival into Europe of anatomically modern humans, the demise of Neanderthals, and an associated major shift in lithic technology. At this stage, however, the degree of interaction between these factors is poorly known, based on fragmentary and widely dispersed data points. In this study we provide important new data from Eastern Europe which indicate that the magnitude of the CI eruption and impact of associated distal ash (tephra) deposits may have been substantially greater than existing models suggest. The scale of the eruption is modelled by tephra distribution and thickness, supported by local data points. CI ashfall extends as far as the Russian Plain, Eastern Mediterranean and northern Africa. However, modelling input is limited by very few data points in Eastern Europe. Here we investigate an unexpectedly thick CI tephra deposit in the southeast Romanian loess steppe, positively identified using geochemical and geochronological analyses. We establish the tephra as a widespread primary deposit, which blanketed the topography both thickly and rapidly, with potentially catastrophic impacts on local ecosystems. Our discovery not only highlights the need to reassess models for the magnitude of the eruption and its role in climatic transition, but also suggests that it may have substantially influenced hominin population and subsistence dynamics in a region strategic for human migration into Europe.