Conflicting reconstructions of Holocene variability of the East Asian summer monsoon (EASM) from speleothem versus other types of proxy records have yielded widely divergent estimates of its phase ...relationship with the Indian summer monsoon (ISM) and Northern Hemisphere summer insolation (NHSI). This apparent discrepancy has been partly attributed to the uncertainties in the climatic representation of Chinese speleothem oxygen isotope (δ18O) records. Here we present a composite speleothem δ18O record of the last ∼14 kyr from Shennong Cave in southeastern China and model-simulated data of rainfall and meteoric δ18O over eastern China. Our synthesis of the proxy-model data suggests that the spatial patterns in both speleothem δ18O and paleo-rainfall over eastern China during the Holocene are diverse at orbital and multi-millennial scales. Our findings imply that: 1) speleothem δ18O in the EASM regime is largely controlled by the large-scale circulation and concomitant latitudinal shifts of the monsoon rain belt; notwithstanding the heterogeneous spatiotemporal pattern of Holocene rainfall as inferred from various proxy records, a coherent orbital-scale speleothem δ18O variability across most Asian monsoon regions (except southeastern China) indeed stems from the NHSI-forced changes in overall monsoon intensity; overall monsoon intensity is not equivalent to monsoon rainfall amount but a manifestation of the large-scale atmospheric circulation; 2) divergent phase relationships with NHSI between speleothem δ18O and other proxy records are consistent with—rather than contradictory to—the NHSI forcing mechanism. Speleothem δ18O and rainfall records reflect two different aspects of the monsoon dynamics. These results may thus, largely help to reconcile the divergent views of the Holocene Asian monsoon variability.
•Holocene speleothem δ18O and rainfall show heterogeneous pattern in eastern China.•East Asian speleothem δ18O reflects large-scale circulation and monsoon rain belt shift.•Divergent phases between speleothem and other proxy records are not contradictory.
Climate changes on Southeastern Tibetan Plateau have important impacts on social and economic development, as well as the ecosystem of southwestern China and Indo-China Peninsula. Here, we collected ...two stalagmites from Shenqi (Miraculous) cave in southern Sichuan, China. The stalagmite δ18O record shows good coherence with local instrumental rainfall record, as well as tree ring- and pollen-based moisture reconstructions from southeastern Tibetan Plateau during overlapped time periods. As a result, we reconstructed high-resolution (∼4.9 yrs) monsoon precipitation variations on southeastern Tibetan Plateau over the past 2300 years by using the combined stalagmite δ18O record.
The result reveals an overall decreasing precipitation trend, with two most notable wet periods occurred in 60–280 AD and 370–510 AD. The most remarkably dry period is the recent 200 years. Some decadal scale wet and dry intervals were also identified. The abnormal drought during 1160–1245 AD might have accelerated Dali kingdom's demise at 1253 AD. Power spectrum analysis indicated significant 373-, 187-, 22-, 12- and 11- yr cycles in our stalagmite record, suggesting the impact of solar activity. Increased monsoon precipitation on southeastern TP was observed in solar activity minima during the last millennium. We further synthesized an integrated precipitation record for southwestern China and discussed spatial patterns of precipitation over China during the last two millennia. The comparisons confirm a "dry southern and wet northern" pattern in monsoonal China during the Medieval Warm Period and a "wet southern and dry northern" pattern during the Little Ice Age and Dark Age Cold Period. Solar activity, the strength of westerly jet and summer monsoon, as well as the SST of tropical Indo-Pacific might play important roles on the rainfall spatial patterns over monsoonal China during the last 2000 years.
•An overall decreasing rainfall trend on SE TP during the past 2300 years.•Increased rainfall during solar activity minima.•A ″dry southern and wet northern" pattern in monsoonal China during the MWP.•A "wet southern and dry northern" pattern during the LIA and DACP.
Oxygen isotope records from Chinese caves characterize changes in both the Asian monsoon and global climate. Here, using our new speleothem data, we extend the Chinese record to cover the full ...uranium/thorium dating range, that is, the past 640,000 years. The record's length and temporal precision allow us to test the idea that insolation changes caused by the Earth's precession drove the terminations of each of the last seven ice ages as well as the millennia-long intervals of reduced monsoon rainfall associated with each of the terminations. On the basis of our record's timing, the terminations are separated by four or five precession cycles, supporting the idea that the '100,000-year' ice age cycle is an average of discrete numbers of precession cycles. Furthermore, the suborbital component of monsoon rainfall variability exhibits power in both the precession and obliquity bands, and is nearly in anti-phase with summer boreal insolation. These observations indicate that insolation, in part, sets the pace of the occurrence of millennial-scale events, including those associated with terminations and 'unfinished terminations'.
•The vicarious traumatization scores for front-line nurses were significantly lower than those of non-front-line nurses;•The vicarious traumatization scores for the general public were significantly ...higher than those of front-line nurses.•Strategies that aim to prevent and treat vicarious traumatization in medical staff and general public are necessary.
Since December 2019, more than 79,000 people have been diagnosed with infection of the Corona Virus Disease 2019 (COVID-19). A large number of medical staff was sent to Wuhan city and Hubei province to aid COVID-19 control. Psychological stress, especially vicarious traumatization caused by the COVID-19 pandemic, should not be ignored. To address this concern, the study employed a total of 214 general public and 526 nurses (i.e., 234 front-line nurses and 292 non-front-line nurses) to evaluate vicarious traumatization scores via a mobile app-based questionnaire. Front-line nurses are engaged in the process of providing care for patients with COVID-19. The results showed that the vicarious traumatization scores for front-line nurses including scores for physiological and psychological responses, were significantly lower than those of non-front-line nurses (P < 0.001). Interestingly, the vicarious traumatization scores of the general public were significantly higher than those of the front-line nurses (P < 0.001); however, no statistical difference was observed compared to the scores of non-front-line nurses (P > 0.05). Therefore, increased attention should be paid to the psychological problems of the medical staff, especially non-front-line nurses, and general public under the situation of the spread and control of COVID-19. Early strategies that aim to prevent and treat vicarious traumatization in medical staff and general public are extremely necessary.
In order to investigate the self-healing behavior of asphalt binder at the molecule scale, the self-healing models of neat and aged asphalt binder with different damage degrees were established by ...introducing a vacuum pad between two layers filled with asphalt molecules. With this model, the self-healing process was simulated at various healing conditions to reveal the effects of oxidative aging, damage degree and healing temperature on the self-healing property. In addition, self-healing efficiency was evaluated using the indexes representative of the characteristics of different self-healing stages. Our results show that the oxidative aging weakened the stacked structure of the asphalt binder and increased the healing activation energy barrier. The increasing damage degree extended the distance for particles to travel, thus prolonging the time required for the crack interfaces contacting with each other. The elevated temperature improved the molecular mobility by supplying more energy to the molecular system. Furthermore, the self-healing process was evaluated quantitatively by the density variation at the crack closing stage and the diffusion coefficient at the intrinsic healing stage. The duration of each stage was influenced by the oxidative aging, damage degree and healing temperature. The findings in this paper are helpful to reveal and evaluate the self-healing property of asphalt binder.
The upper Hanjiang River region is the recharge area of the middle route of South-to-North Water Transfer Project. The region is under construction of the Hanjiang-Weihe River Water Transfer Project ...in China. Monsoon precipitation variations in this region are critical to water resource and security of China. In this study, high-resolution monsoon precipitation variations were reconstructed in the upper Hanjiang River region over the past 6650 years from δ18O and δ13C records of four stalagmites in Xianglong cave. The long term increasing trend of stalagmite δ18O record since the middle Holocene is consistent with other speleothem records from monsoonal China. This trend follows the gradually decreasing Northern Hemisphere summer insolation, which indicates that solar insolation may control the orbital-scale East Asian summer monsoon (EASM) variations. Despite the declined EASM intensity since the middle Holocene, local precipitation may not have decreased remarkably, as revealed by the δ13C records. A series of centennial- to decadal-scale cyclicity was observed, with quasi-millennium-, quasi-century-, 57-, 36- and 22-year cycles by removing the long-term trend of stalagmite δ18O record. Increased monsoon precipitation during periods of 4390–3800 a BP, 3590–2960 a BP, 2050–1670 a BP and 1110–790 a BP had caused four super-floods in the upper reach of Hanjiang River. Dramatically dry climate existed in this region during the 5.0 ka and 2.8 ka events, coinciding with notable droughts in other regions of monsoonal China. Remarkably intensified and southward Westerly jet, together with weakened summer monsoon, may delay the onset of rainy seasons, resulting in synchronous decreasing of monsoon precipitation in China during the two events. During the 4.2 ka event and the Little Ice Age, the upper Hanjiang River region was wet, which was similar to the climate conditions in central and southern China, but was the opposite of drought observed in northern China. We propose that weakened summer monsoon and less strengthened or normal Westerly jet may cause rain belt stay longer in the southward region, which reduced rainfall in northern China but enhanced it in central and southern China.
•Monsoon precipitation reconstruction in the upper Hanjiang River over the past 6650 years.•Dramatically dry climate existed during the 5.0 ka and 2.8 ka events.•Wet 4.2 ka event and the Little Ice Age were observed.•Interplay of Westerly jet and Asian summer monsoon controlled regional precipitation changes.
The ubiquitination status of RIPK1 is considered to be critical for cell fate determination. However, the in vivo role for RIPK1 ubiquitination remains undefined. Here we show that mice expressing ...RIPK1
which is defective in RIPK1 ubiquitination die during embryogenesis. This lethality is fully rescued by concomitant deletion of Fadd and Ripk3 or Mlkl. Mechanistically, cells expressing RIPK1
are more susceptible to TNF-α induced apoptosis and necroptosis with more complex II formation and increased RIPK1 activation, which is consistent with the observation that Ripk1
lethality is effectively prevented by treatment of RIPK1 kinase inhibitor and is rescued by deletion of Tnfr1. However, Tnfr1
Ripk1
mice display systemic inflammation and die within 2 weeks. Significantly, this lethal inflammation is rescued by deletion of Ripk3. Taken together, these findings reveal a critical role of Lys376-mediated ubiquitination of RIPK1 in suppressing RIPK1 kinase activity-dependent lethal pathways during embryogenesis and RIPK3-dependent inflammation postnatally.
Frozen water is the most widespread type of ice present in ice caves and forms ice stalagmites and stalactites as well as floor ice, which is often several meters thick. Organic macroremains are ...commonly rare in this type of cave ice, which makes it difficult to establish a chronology and severely limits the use of such ice deposits as paleoenvironmental archives. Here, the chronology of such ice deposits in the inner part of the glaciated Eisriesenwelt, one of the world's largest ice caves located in the European Alps of Austria, is determined by a combination of radiocarbon and
Th dating of cryogenic calcite. The data suggest that this cave ice has formed over the last three millennia, with a marked increase in the average accumulation rate during the thirteenth century, coinciding with the onset of the Little Ice Age in the Alps. Data from a second site closer to the entrance suggests that large parts of this tourist cave were likely ice-free during the Medieval Warm Period and that a substantial part of the ice is probably a relic of the Little Ice Age. The current warming has already penetrated deeper into the cave than during the Medieval Warm Period, although air exchange during the warm season is restricted by a door at the cave entrance.
Electromagnetic interference (EMI) has drawn great attention in recent years. In this particular case, it is generated by the three-phase inverters in power electronics applications due to the power ...devices turning on and off at high frequency. In this paper, in order to alleviate such EMI noise, a high-frequency common-mode (CM) equivalent model is developed, which leverages the effect of parasitic parameters. Meanwhile, in order to eliminate the effect of the parasitic capacitance between the phase node and ground, which is the cause of main CM noise propagation, a coupled inductor connected with a capacitor circuit, which is equivalent to a negative capacitance is proposed. The parameter calculation for the passive negative capacitance circuit is given in detail. The experimental results demonstrated the effectiveness of the circuitry structure and its ability to reduce CM noise.
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