AVEID: Automatic Video System for Measuring Engagement In Dementia

Engagement in dementia is typically measured using behavior observational scales (BOS) that are tedious and involve intensive manual labor to annotate, and are therefore not easily scalable. We propose AVEID, a low cost and easy-to-use video-based engagement measurement tool to determine the engagement level of a person with dementia (PwD) during digital interaction. We show that the objective behavioral measures computed via AVEID correlate well with subjective expert impressions for the popular MPES and OME BOS, confirming its viability and effectiveness. Moreover, AVEID measures can be obtained for a variety of engagement designs, thereby facilitating large-scale studies with PwD populations

Evolution and development of Miocene “island dolostones” on Xisha Islands, South China Sea

On Xisha Islands, located in the South China Sea, the Neogene succession includes the unconformity-bounded Huangliu Formation that is 210.5 m thick in well CK-2 and formed almost entirely of dolostones. The diverse biota in the Huangliu Formation, which includes corals, algae, bivalves and foraminifera, indicates that the original carbonate sediments accumulated in water that was < 30 m deep. The dolostones are formed of various mixtures of low- and high-calcium calcian dolomite with limpid dolomite lining the walls of many cavities. The O-18 and C-13 stable isotopes suggest that dolomitization was mediated by slightly modified seawater. The Sr-87/Sr-86 ratios from the dolostones suggest that dolomitization took place similar to 9.4 and 2.3 Ma ago, with the age of dolomitization becoming progressively younger towards the top of the formation. "Island dolostones" like these, found on many islands throughout the Pacific Ocean and the Caribbean Sea, have commonly been linked to eustatic changes in sea-level with dolomitization taking place during lowstands, highstands, or transgressive phases. Data from the Huangliu Formation in well CK-2 suggests that dolomitization was associated with (semi-) continuous transgressive conditions that were controlled by the interaction of tectonic subsidence and eustatic changes in sea level

Coral geochemical record of submarine groundwater discharge back to 1870 in the northern South China Sea

The importance of submarine groundwater discharge (SGD) is becoming increasingly recognized because of its potential significance as a source of dissolved species. To explore the probable coral geochemical signal of SGD and verify the validity of potential reliable proxies, multiple geochemical proxies over the last 137 years were identified from a Porites coral near a subterranean estuary in the northern South China Sea, where the SGD was reported to be the predominant flux of terrestrial waters to the coastal ocean. Results indicated that the SGD in the coastal zone was the dominant source of trace elements, especially REE and Ba, due to the various dissolution reactions occurring during groundwater flow in the karst terrain. The time- and frequency-domain comparison between the coral geochemical proxy and the local/regional precipitation indicated that coral REE/Ca ratios are predominantly impacted by the SGD associated with local precipitation, while coral Ba/Ca ratios are also affected by the primary productivity and allochthonous seawater Ba from surrounding areas. The REE signal from coral allows us to reconstruct the coastal surface seawater REE concentrations and the SGD rates on the coast of Sanya during 1870–2006. In a novel approach to developing a proxy for historic SGD to coastal waters, this study provides evidence that the coral REE/Ca record from the karst coast with large SGD has potentials to be a promising paleohydrological indicator

Annual REE Signal of East Asian Winter Monsoon in Surface Seawater in the Northern South China Sea: Evidence From a Century-Long Porites Coral Record

The East Asian winter monsoon (EAWM) plays a significant role in the Asian climate system. However, the scarcity of direct high-resolution records, especially those covering recent centuries, limits our understanding of monsoonal dynamics. Here we present a reconstruction of annual EAWM strength over the past century and a half using a Porites coral from Yongxing Island in the northern South China Sea (SCS), where the variations in the rare earth element (REE) parameters in surface seawater are dominantly controlled by the input of aeolian dust. Our record indicates that the EAWM strength weakly increased overall during the latter half of the nineteenth century but decreased during the twentieth century, especially after similar to 1950 Common Era. Additionally, during the past century and a half, the relationship between the EAWM and the East Asian summer monsoon, as recorded in speleothems, varied temporally and depended on the strength of the EAWM. Our findings suggest that the REE proxy of corals from the offshore SCS can be applied as an excellent indicator of the winter monsoon strength

Strontium isotope stratigraphy and paleomagnetic age constraints on the evolution history of coral reef islands, northern South China Sea

Understanding the history of the response of coral reefs to past climate changes can provide valuable information for predicting the future response of modern reefs. However, dating such ancient biotic carbonate is still challenging because of its sensitivity to diagenetic alteration processes, scarcity of well-preserved fossils, and low magnetic mineral content. There have been a long debates about the origin and evolutionary history of coral reefs in the northern South China Sea, mainly due to the lack of direct and reliable age constraints. This provides us with a good opportunity to verify the practicability of different dating approaches, especially the strontium (Sr) isotope analysis of bulk carbonate. Here, we retrieved a 972.55-m-long core from the Xisha Islands to provide a credible chronologic constraint on the carbonate platform evolution. The lithostratigraphy, strontium isotope stratigraphy, and magnetostratigraphy were analyzed throughout the whole reef sequence. The lithostratigraphic results show that the 873.55 m reef sequence developed on an ancient volcaniclastic basement and experienced multiple evolutionary phases. The Sr-87/Sr-86 results of all 100 bulk carbonate samples vary from 0.708506 to 0.709168 and show a monotonic increase with decreasing depth, except for a few outliers. Trace-element criteria and stable isotope (delta O-18 and delta C-13) methods were applied to these bulk carbonate samples, and results imply that the primary or near-primary-seawater Sr-87/Sr-86 values were likely preserved, although different degrees of diagenetic alteration occurred. In addition, the paleomagnetic results indicate 10 normal polarity and eight reversed polarity magnetozones. Based on the Sr-87/Sr-86 ratios of the selected 58 samples and paleomagnetic reconstruction of polarity reversals, the bottom of the reef sequence is dated to 19.6 Ma, and the observed polarity chronozones extend from chron C6 (19.722-18.748 Ma) at 866.60 m to present at the top. Based on the new data, we propose a new chronologic framework for the evolutionary history of the reef islands, where: (1) the reefs initiated in the early Miocene (19.6 Ma) and were drowned until 16.26 Ma; (2) during 16.26-10.66 Ma, lagoon to lagoon slope environments prevailed; (3) the lagoon environment progressively transformed into a reef crest environment from 10.66 to 4.36 Ma and 4.36 to 1.59 Ma; and (4) the reef started to be drowned again during 1.59-0 Ma. Our study provides a new and reliable chronologic constraint on the general evolutionary history of the reef islands in the northern South China Sea. Furthermore, the Sr-87/Sr-86 results from bulk carbonate indicate that strontium isotope stratigraphy is a powerful dating tool only when rigid sample selection, sequential leaching procedures, and strict trace-element and isotopic criteria are applied

Porites coral on a remote reef reveal marine phosphorus biogeochemical cycling following artificial disturbance

Excess anthropogenic phosphorus (P) supplied to marine systems, which may subsequently jeopardize ecosystem structure and function, has altered the P balance and quadrupled its flow. However, due to the diversity of P sources, the unpredictability and variability of human activities, and the absence of long‐term records, it remains uncertain how long the effects of excess P persist in aquatic ecosystems, and whether it stimulates gross primary productivity. In this study, we utilized geochemical proxies in coral skeletons from an atoll in the Xisha Islands of the South China Sea to reconstruct historical patterns of P in surface seawater. This atoll has remained in a natural state for an extended period of time, except for a short period of unambiguously documented guano extraction. Analyses of coral skeletons dating back to 1851 CE distinctly show that the P concentration in surface seawater increased abnormally in the 1960s. We deduced that guano extraction at that time led to an abrupt increase in the long‐term equilibrium of seawater P concentration. Subsequent P addition appeared to have continued for at least ~30 years after phosphorite exploitation ceased, and P showed a decay period that was longer than that of other elements. Similar temporal trends of coral P/Ca and δ13C indicated that elevated marine primary productivity was associated with increased P. Large inputs within a short period, as well as the continued influence of P over the long term, can serve as a natural ecological analog for coral reefs subject to nutrient contamination

Coral reef carbonate record of the Pliocene-Pleistocene climate transition from an atoll in the South China Sea

As a natural laboratory for testing various paleoclimatological and paleoceanographic hypotheses, the Pliocene-Pleistocene stratigraphic sequence from a full-coring major scientific drilling (Well CK2 with total length: 928.75 m) in Yongle atoll of Xisha Islands, northern South China Sea was studied. The Petrography of studied section of the core was dominated by reef carbonate limestones which contain abundant shallow marine organisms, e.g., coralline algae, corals, and foraminifera, which almost consisted of pure carbonates and preserved the primary geochemical message since Pliocene. According to the isolation of Well CK2 and the provenance of elements, the systematic changes and abrupt points of isotope and element geochemical compositions (rare earth element parameters, SiO content, Al/Ti ratio, etc.) from coral reef carbonate record presented the elevated terrigenous influences related to the East Asian monsoon after ~2.6 Ma BP, as part of the Pliocene-Pleistocene climate transition. Our results demonstrated that the continental weathering controlled by the East Asian summer monsoon dominated the surface seawater compositions of study area before ~2.6 Ma BP, when the winter monsoon was not strong enough to exert significant influences. Then, the effects of eolian dust associated with the intensity of East Asian winter monsoon, the precipitation driven by summer monsoon, and the global temperature, which played different roles at different periods after ~2.6 Ma BP, should be considered. Our results confirmed that the potentials and significances of shallow-water carbonate deposition from coral reefs, and provided a unique perspective to shed light on the carbonate record of climate changes