Explicit interactive modelling and implicit interpolation modelling are the two classic three-dimensional (3-D) modelling approaches for reconstructing 3-D geological structures from sparse data. The ...limitations of using a single method appear when performing complex regional modelling containing various types of geological structures. However, due to the complication of spatial geometry computation, the integration and coupling of explicit and implicit modelling approaches and modelling results remain difficult and unresolved. In this paper, we propose an explicit-implicit-integrated 3-D geological modelling approach for the geometric fusion of different types of complex geological structure models. First, suitable methods were chosen to model different types of structures. For example, a Hermite Radial Basis Function (HRBF)-based implicit method was used to model general strata, faults, and folds from geological boundaries and attitudes in a regional geological map; explicit approaches, such as the skinning method and the free-form surface, were used to model local detailed structures, such as Quaternary deposits, monoclinic strata and multi-layer volcanic edifices, from section-constrained data. Finally, the explicit models were resampled and converted to implicit models and were coupled with the implicit models, leading to the integrated regional modelling of various types of geological structures. The validity of the proposed method was tested using the geological map of the Xianyan Demolition Volcano in Fujian. The results demonstrate that the proposed explicit-implicit-integrated 3-D geological modelling approach is efficient and effective, and this approach provides a probable solution for coupling and integrating multiple modelling methods and geological models for an area containing complex geological structures. The 3-D model established using this method can directly reflect the geomorphic features and volcanic passage facies of the Xianyan Demolition Volcano. Moreover, the simulation of radioactive fractures around the center of the volcano can also help to accurately determine the volcano type.
•Integration and coupling of several explicit and implicit modelling approaches for multiple types of geological structures.•Automatic 3-D geological modelling containing complex structures, such as faults, folds, Quaternary and volcano edifice.•Geometrically coupled multi-body modelling and topological consistency.
The first online modern organic-walled dinoflagellate cyst determination key has been launched at www.marum.de/dinocystkey.html. This key is based on easily recognisable morphological features of ...dinoflagellate cysts that can be observed using standard transmitted light microscopy. To date, the key includes 96 cyst species that can be found in late Quaternary marine sediments. This key is free of charge to users, and will be continuously updated and improved by the authors. For each individual species of dinoflagellate cyst, the website provides information on its defining morphological characteristics and the cyst—motile stage relationship. It gives a comparison with other morphologically similar taxa, links to publications with original cyst descriptions and outlines their modern global distribution where this information is available. All species descriptions are illustrated by line drawings showing their most distinctive characteristics, and accompanied by high-quality bright-field photomicrographs. The key is compatible with all major computing platforms (including smartphones) and software.
Polar bear (Ursus maritimus) is the apex predator of the Arctic, largely dependent on sea-ice. The expected disappearance of the ice cover of the Arctic seas by the mid 21st century is predicted to ...cause a dramatic decrease in the global range and population size of the species. To place this scenario against the backdrop of past distribution changes and their causes, we use a fossil dataset to investigate the polar bear's past distribution dynamics during the Late Glacial and the Holocene. Fossil results indicate that during the last deglaciation, polar bears were present at the southwestern margin of the Scandinavian Ice Sheet, surviving until the earliest Holocene. There are no Arctic polar bear findings from 8000–6000 years ago (8–6 ka), the Holocene's warmest period. However, fossils that date from 8-9 ka and 5–6 ka suggest that the species likely survived this period in cold refugia located near the East Siberian Sea, northern Greenland and the Canadian Archipelago. Polar bear range expansion is documented by an increase in fossils during the last 4000 years in tandem with cooling climate and expanding Arctic sea ice. The results document changes in polar bear's distribution in response to Late Glacial and Holocene Arctic temperature and sea ice trends.
•At the end of the last glacial period, from 15 to 11 ka, polar bears were present in the western coast of Scandinavia (Denmark, Sweden, Norway, Iceland), until this Scandinavian subpopulation went regionally extinct in the early Holocene, about 11.5 ka•No polar bear remains have been discovered from the period 8 to 6 ka anywhere in the Arctic, but the findings from Svalbard and eastern arctic Siberia 8–9 thousand years ago and from NW Greenland after 6 ka suggest that the likely refugia of the polar bear during the Holocene thermal maximum were in the High Arctic fringes of the Arctic Basin.•During the last four millennia there has been a significant expansion of the polar bear's range, driven by a cooling trend and associated expansion of the arctic sea ice, until the onset of the current, human-induced warming.•Our results highlight the dynamism of the polar bear's distribution range in response to changes in high-latitude climate and Arctic sea ice conditions.
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•A multifunctional food packaging film with antifogging and antibacterial properties was designed.•The functional film can prolong the shelf life of fruits and has broad application ...prospects.•A simple quaternization modification enabled the coating to achieve dual functions.•Chitosan is used as matrix which has good biocompatibility and biodegradability.•Water is used as solvent and the progress of film preparation is green and safe.
In this work, a multifunctional food packaging composite coating with transparent, biodegradable, antifogging and antibacterial properties was designed and fabricated by quaternary ammonium salt modified chitosan (HACC) and poly (vinyl alcohol) (PVA) via a facile and environment-friendly solution casting method. A simple quaternization modification enabled the coating simultaneously to achieve excellent antifogging and antibacterial functions. The excellent antifogging property of the HACC/PVA composite coating was attributed to the strong water absorbency of quaternary ammonium chitosan and PVA. A nearly 98% transmittance ratio of coated glasses was achieved during antifogging test. In addition, the inhibition rate of the HACC/PVA composite coating kill against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Botrytis cinerea were up to ~99%. The antibacterial effect was demonstrated by each group of strawberries after storage for 1, 3, 5 days. The multifunctional coating has broad prospects in the application of fruit and vegetable packaging.
The North Atlantic Oscillation (NAO) is the major source of variability in winter atmospheric circulation in the Northern Hemisphere, with large impacts on temperature, precipitation and storm ...tracks, and therefore also on strategic sectors such as insurance, renewable energy production, crop yields and water management. Recent developments in dynamical methods offer promise to improve seasonal NAO predictions, but assessing potential predictability on multi-annual timescales requires documentation of past low-frequency variability in the NAO. A recent bi-proxy NAO reconstruction spanning the past millennium suggested that long-lasting positive NAO conditions were established during medieval times, explaining the particularly warm conditions in Europe during this period; however, these conclusions are debated. Here, we present a yearly NAO reconstruction for the past millennium, based on an initial selection of 48 annually resolved proxy records distributed around the Atlantic Ocean and built through an ensemble of multivariate regressions. We validate the approach in six past-millennium climate simulations, and show that our reconstruction outperforms the bi-proxy index. The final reconstruction shows no persistent positive NAO during the medieval period, but suggests that positive phases were dominant during the thirteenth and fourteenth centuries. The reconstruction also reveals that a positive NAO emerges two years after strong volcanic eruptions, consistent with results obtained from models and satellite observations for the Mt Pinatubo eruption in the Philippines.
The Late-Quaternary climate of Beringia remains unresolved despite the region's role in modulating glacial-interglacial climate and as the likely conduit for human dispersal into the Americas. Here, ...we investigate Beringian temperature change using an ∼32,000-year lacustrine record of leaf wax hydrogen isotope ratios (δ2Hwax) from Arctic Alaska. Based on Monte Carlo iterations accounting for multiple sources of uncertainty, the reconstructed summertime temperatures were ∼3 °C colder (range: −8 to +3 °C) during the Last Glacial Maximum (LGM; 21-25 ka) than the pre-industrial era (PI; 2–0.1 ka). This ice-age summer cooling is substantially smaller than in other parts of the Arctic, reflecting altered atmospheric circulation and increased continentality which weakened glacial cooling in the region. Deglacial warming was punctuated by abrupt events that are largely synchronous with events seen in Greenland ice cores that originate in the North Atlantic but which are also controlled locally, such as by the opening of the Bering Strait between 13.4 and 11 ka. Our reconstruction, together with climate modeling experiments, indicates that Beringia responds more strongly to North Atlantic freshwater forcing under modern-day, open-Bering Strait conditions than under glacial conditions. Furthermore, a 2 °C increase (Monte Carlo range: −1 to +5 °C) over the anthropogenic era reverses a 6 °C decline (Monte Carlo range: −10 to 0 °C) through the Holocene, indicating that recent warming in Arctic Alaska has not surpassed peak Holocene summer warmth.
•Alaska's climate history is evaluated using leaf wax hydrogen isotope ratios in a 32,000 year-long lacustrine record.•The record reveals mild ice-age cooling, abrupt deglacial climate events, strong Holocene cooling, and recent warming.•Proxy-model comparison highlights the importance of the Bering Strait opening as a control of Beringian climate.
Two fossilized human crania (Apidima 1 and Apidima 2) from Apidima Cave, southern Greece, were discovered in the late 1970s but have remained enigmatic owing to their incomplete nature, taphonomic ...distortion and lack of archaeological context and chronology. Here we virtually reconstruct both crania, provide detailed comparative descriptions and analyses, and date them using U-series radiometric methods. Apidima 2 dates to more than 170 thousand years ago and has a Neanderthal-like morphological pattern. By contrast, Apidima 1 dates to more than 210 thousand years ago and presents a mixture of modern human and primitive features. These results suggest that two late Middle Pleistocene human groups were present at this site-an early Homo sapiens population, followed by a Neanderthal population. Our findings support multiple dispersals of early modern humans out of Africa, and highlight the complex demographic processes that characterized Pleistocene human evolution and modern human presence in southeast Europe.
Contentious observations of Pleistocene shoreline features on the tectonically stable islands of Bermuda and the Bahamas have suggested that sea level about 400,000 years ago was more than 20 metres ...higher than it is today. Geochronologic and geomorphic evidence indicates that these features formed during interglacial marine isotope stage (MIS) 11, an unusually long interval of warmth during the ice age. Previous work has advanced two divergent hypotheses for these shoreline features: first, significant melting of the East Antarctic Ice Sheet, in addition to the collapse of the West Antarctic Ice Sheet and the Greenland Ice Sheet; or second, emplacement by a mega-tsunami during MIS 11 (ref. 4, 5). Here we show that the elevations of these features are corrected downwards by ∼10 metres when we account for post-glacial crustal subsidence of these sites over the course of the anomalously long interglacial. On the basis of this correction, we estimate that eustatic sea level rose to ∼6-13 m above the present-day value in the second half of MIS 11. This suggests that both the Greenland Ice Sheet and the West Antarctic Ice Sheet collapsed during the protracted warm period while changes in the volume of the East Antarctic Ice Sheet were relatively minor, thereby resolving the long-standing controversy over the stability of the East Antarctic Ice Sheet during MIS 11.
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