Aim Precipitation manipulation experiments have shown diverse terrestrial carbon (C) cycling responses when the ecosystem is subjected to different magnitudes of altered precipitation, various experimental durations or heterogeneity in local climate. However, how these factors combine to affect C cycle responses to changes in precipitation remains unclear. Location Global. Time period 1990–2019. Major taxa studied Terrestrial ecosystems. Methods Using observations from 230 published studies in which precipitation was manipulated and terrestrial C cycling variables were measured, we conducted a global meta‐analysis to investigate responses of diverse C cycle processes to altered precipitation, including gross ecosystem productivity, ecosystem respiration, net ecosystem productivity, ecosystem carbon use efficiency, net primary productivity (NPP), aboveground and belowground NPP, aboveground and belowground biomass, shoot‐to‐root ratio, soil respiration and soil microbial biomass C. Results We found that C cycling responses were correlated linearly and positively with the magnitude of precipitation treatments. We also detected that the responses of NPP and its aboveground component (ANPP) to altered precipitation weakened with experimental duration. Furthermore, gross ecosystem productivity, ecosystem respiration and net ecosystem productivity showed larger responses to precipitation treatments of greater magnitude over shorter time periods. The response of soil respiration, a key component of the C budget in most terrestrial ecosystems, depended in particular on the local climate. Local temperature and precipitation not only influenced the magnitude of the response of soil respiration to altered precipitation but also affected its sensitivity to the magnitude of the precipitation treatments, with higher sensitivities in the response of soil respiration to treatment magnitude at drier and colder sites. Main conclusions Our findings highlight the importance of the interactions between the magnitude of precipitation treatments, their duration and the local climate in the response of ecosystem C cycling to altered precipitation, which is crucial to a better understanding of ecosystem C processes and functioning and projecting them under changing precipitation regimes.

The aim of this research was to study the anatomical shape of the maxillary first premolars in Chinese people using cone-beam computed tomography (CBCT). The anatomical morphology of root canals and crowns of 637 first premolars from China was observed by CBCT. In this study, 73.3% of the 637 maxillary first premolars were single roots, 26.7% were double roots, and 41.8%(n = 266) of the 637 maxillary first premolars were type IV in the light of Vertucci. The most frequent distance between two root canal orifices was 2-3mm (n = 257, 47.6%). There was a range in distance from the top of the medullary chamber to the central fossa (from 4.25mm to 4.45mm), with a mean distance of 4.35 ± 0.62mm. The incidence of mesial depression was 65.6%, and the mean angle of the mesial depression was 151.8 ± 10.5 degrees. In conclusion, the root canal system and anatomical morphology of the maxillary first premolar in the Chinese population exhibit a wide range of morphologies based on CBCT.

Extremely low frequency pulsed magnetic fields (MFs) have been increasingly used as an effective method in oral therapy, but its potential impact on health has not been clarified. In this study, we investigated the impact of 10 Hz pulsed MF exposure on primary human gingival fibroblasts (HGFs) derived from eight healthy persons (four males and four females). Cells were exposed to 10 Hz pulsed MFs at 1.0 mT for 24 h. Cell apoptosis, cell cycle progression, intracellular reactive oxygen species levels, DNA damage, and cell proliferation were determined after exposure. The results showed that 10 Hz pulsed MFs exposure have slight effects on cellular apoptosis, cell cycle progression, and DNA damage in primary HGFs from some but not all samples. In addition, no significant effect was found on cell proliferation. Bioelectromagnetics. 43:476-490, 2022.