Harmonicity Spectrum

Perceiving harmonic information (especially weak harmonic information) in time series has important scientific and engineering significance. Fourier spectrum and time-frequency spectrum are commonly used tools for perceiving harmonic information, but they are often ineffective in perceiving weak harmonic signals because they are based on energy or amplitude analysis. Based on the theory of Normal time-frequency transform (NTFT) and complex correlation coefficient, a new type of spectrum, the Harmonicity Spectrum (HS), is developed to perceive harmonic information in time series. HS is based on the degree of signal harmony rather than energy or amplitude analysis, and can therefore perceive very weak harmonic information in signals sensitively. Simulation examples show that HS can detect harmonic information that cannot be detected by Fourier spectrum or time-frequency spectrum. Acoustic data analysis shows that HS has better resolution than traditional LOFAR spectrum.

Rising trends of global precipitable water vapor and its correlation with flood frequency

Using 4 global reanalysis data sets, significant upward trends of precipitable water vapor(PWV) were found in the 3 time periods of 1958-2020, 1979-2020, and 2000-2020. During 1958-2020, the global PWV trends obtained using the ERA5 and JRA55 data sets are 0.19 ± 0.01 mm per decade(1.15 ± 0.31%)and 0.23 ± 0.01 mm per decade(1.45 ± 0.32%), respectively. The PWV trends obtained using the ERA5,JRA55, NCEP-NCAR, and NCEP-DOE data sets are 0.22 ± 0.01 mm per decade(1.18 ± 0.54%),0.21 ± 0.00 mm per decade(1.76 ± 0.56%), 0.27 ± 0.01 mm per decade(2.20 ± 0.70%) and 0.28 ± 0.01 mm per decade(2.19 ± 0.70%) for the period 1979-2020. During 2000-2020, the PWV trends obtained using ERA5, JRA55, NCEP-DOE, and NCEP-NCAR data sets are 0.40 ± 0.25 mm per decade(2.66 ± 1.51%),0.37 ± 0.24 mm per decade(2.19 ± 1.54%), 0.40 ± 0.26 mm per decade(1.96 ± 1.53%) and 0.36 ± 0.25 mm per decade(2.47 ± 1.72%), respectively. Rising PWV has a positive impact on changes in precipitation,increasing the probability of extreme precipitation and then changing the frequency of flood disasters.Therefore, exploring the relationship between PWV(derived from ERA5 and JRA55) change and flood disaster frequency from 1958 to 2020 revealed a significant positive correlation between them, with correlation coefficients of 0.68 and 0.79, respectively, which explains the effect of climate change on the increase in flood disaster frequency to a certain extent. The study can provide a reference for assessing the evolution of flood disasters and predicting their frequency trends.

On Inversion of Continuous Wavelet Transform

This study deduces a general inversion of continuous wavelet transform (CWT) with timescale being real rather than positive. In conventional CWT inversion, wavelet’s dual is assumed to be a reconstruction wavelet or a localized function. This study finds that wavelet’s dual can be a harmonic which is not local. This finding leads to new CWT inversion formulas. It also justifies the concept of normal wavelet transform which is useful in time-frequency analysis and time-frequency filtering. This study also proves a law for CWT inversion: either wavelet or its dual must integrate to zero.

Matching mechanism in global public goods games:a case of climate protection

In the setting of dealing with climate change, this article designs a matching mechanism for global public goods provision with the aggregative game approach. Given endowment and the technology of each country, we propose the conditions under which the matching mechanism is able to guarantee full participation and Pareto efficient provision, respectively, in the cases with certain and uncertain preference information. These conditions cannot only be adopted in international negotiation and cooperation, but also refines the theory of matching game. In comparative static analyses, we discover that: First, changes of initial stock of climate goods produce a wealth effect and the crowd-out effect is less than 1. Second, climate tax policies affect the supply and welfare of each country only when they produce wealth effects, and if tax revenue is transferred into climate goods with more advanced technology, they will produce positive wealth effects. Third, modifying matching plans dynamically and appropriately can urge countries to improve technology, and especially given a Pareto optimal mechanism, adjusting the matching plan to keep marginal rates of transformation unchanged as technology changes is still able to ensure full participation and efficient supply of climate goods.

Global and regional soil organic carbon estimates:Magnitudes and uncertainties

Globally,soil is the largest terrestrial carbon(C)reservoir.Robust quantification of soil organic C(SOC)stocks in existing global observation-based estimates avails accurate predictions in carbon-climate feedbacks and future climate trends.We investigated the magnitudes and distributions of global and regional SOC estimates(i.e.,density and stocks)based on five widely used global gridded SOC datasets,a regional permafrost dataset developed in 2021(UM2021),and a global-scale soil profile database(World Soil Information Service)reporting measurements of a series of physical and chemical edaphic attributes.The five global gridded SOC datasets were the Harmonized World Soil Database(HWSD),World Inventory of Soil Emission Potentials at 30 arc-second resolution(WISE30sec),Global Soil Dataset for Earth System Models(GSDE),Global Gridded Soil Information at 250-m resolution(SoilGrids250m),and Global Soil Organic Carbon Map(GSOCmap).Our analyses showed that the magnitude and distribution of SOC varied widely among datasets,with certain datasets showing region-specific robustness.At the global scale,SOC stocks at the top 30 and 100 cm were estimated to be 828(range:577–1171)and 1873(range:1086–2678)Pg C,respectively.The estimates from GSDE,GSOCmap,and WISE30sec were comparable,and those of SoilGrids250m and HWSD were at the upper and lower ends.The spatial SOC distribution varied greatly among datasets,especially in the northern circumpolar and Tibetan Plateau permafrost regions.Regionally,UM2021 and WISE30sec performed well in the northern circumpolar permafrost regions,and GSDE performed well in China.The estimates of SOC by different datasets also showed large variabilities across different soil layers and biomes.The discrepancies were generally smaller for the 0–30 cm soil than the 0–100 cm soil.The datasets demonstrated relatively higher agreement in grasslands,croplands,and shrublands/savannas than in other biomes(e.g.,wetlands).The users should be mindful of the gaps between regions and biomes while choosing the most appropriate SOC dataset for specific uses.Large uncertainties in existing global gridded SOC estimates were generally derived from soil sampling density,different sources,and various mapping methods for soil datasets.We call for future efforts for standardizing soil sampling efforts,cross-dataset comparison,proper validation,and overall global collaboration to improve SOC estimates.

Decoding bone-inspired and cell-instructive cues of scaffolds for bone tissue engineering

Bone fractures are common occurrence in clinical settings,creating a high demand for effective repair material.Unfortunately,limited graft availability,donor site morbidities,unpredictable clinical outcomes,immunologic reactions,infection risks,and geometrical mismatching concerns hampered tissue graft use and underscored the need for scaffolds for more effective bone reconstructions due to their tunable properties.Significant progress has been carried out in past decade in the fields of nanoceramics synthesis,bioconjugate chemistry,and composite material processing.This review outlines hierarchical structures and biology of bone tissue,materialistic compo-nents of scaffolds(bioceramics,polymers,bioactive drugs),featured scaffolding strategies(nanofibers,hydrogels,aerogels,bioprinting,and fiber-reinforced composite),and emphasis that hierarchical and physiochemical char-acteristics of bone should be used as an inspiration for scaffold design.This review discussed how differences in materiobiological aspects of scaffolds,such as polymer/bioceramic nanocomposite,mineralized nanocomposite,matrix-rich nanocomposite,3D microenvironmental cues,pore space cues,mechanical cues,usage of physical stimulation(magnetic,electroactive,and photoactivated cues),surface cues(wettability,roughness,textured,and surface charge),and biointerface cues(cell-biomaterial interactions,cell-selective homing,and cell regula-tory strategies)modulate cellular and biological response for bone tissue engineering.This study further outlines the challenges and benefits of integrating materiobiological cues of scaffolds for bone tissue engineering.

Most root-derived carbon inputs do not contribute to long-term global soil carbon storage

Plant root-derived carbon(C)inputs(I_(root))are the primary source of C in mineral bulk soil.However,a fraction of I_(root)may lose quickly(I_(loss),e.g.,via rhizosphere microbial respiration,leaching and fauna feeding)without contributing to long-term bulk soil C storage,yet this loss has never been quantified,particularly on a global scale.In this study we integrated three observational global data sets including soil radiocarbon content,allocation of photo synthetically assimilated C,and root biomass distribution in 2,034 soil profiles to quantify I_(root)and its contribution to the bulk soil C pool.We show that global average I_(root)in the 0-200 cm soil profile is 3.5 Mg ha^(-1)yr^(-1),~80%of which(i.e.,I_(loss))is lost rather than co ntributing to long-term bulk soil C storage.I_(root)decreases exponentially with soil depth,and the top 20 cm soil contains>60%of total I_(root).Actual C input contributing to long-term bulk soil storage(i.e.,I_(root)-I_(loss))shows a similar depth distribution to I_(root).We also map I_(loss)and its depth distribution across the globe.Our results demonstrate the global significance of direct C losses which limit the contribution of I_(root)to bulk soil C storage;and provide spatially explicit data to facilitate reliable soil C predictions via separating direct C losses from total root-derived C inputs.

Strontium modulates osteogenic activity of bone cement composed of bioactive borosilicate glass particles by activating Wnt/β-catenin signaling pathway

There is a need for synthetic grafts to reconstruct large bone defects using minimal invasive surgery.Our previous study showed that incorporation of Sr into bioactive borate glass cement enhanced the osteogenic capacity in vivo.However,the amount of Sr in the cement to provide an optimal combination of physicochemical properties and capacity to stimulate bone regeneration and the underlying molecular mechanism of this stimulation is yet to be determined.In this study,bone cements composed of bioactive borosilicate glass particles substituted with varying amounts of Sr(0 mol%to 12 mol%SrO)were created and evaluated in vitro and in vivo.The setting time of the cement increased with Sr substitution of the glass.Upon immersion in PBS,the cement degraded and converted more slowly to HA(hydroxyapatite)with increasing Sr substitution.The released Sr2+modulated the proliferation,differentiation,and mineralization of hBMSCs(human bone marrow mesenchymal stem cells)in vitro.Osteogenic characteristics were optimally enhanced with cement(designated BG6Sr)composed of particles substituted with 6mol%SrO.When implanted in rabbit femoral condyle defects,BG6Sr cement supported better peri-implant bone formation and bone-implant contact,comparing to cements substituted with 0mol%or 9mol%SrO.The underlying mechanism is involved in the activation of Wnt/β-catenin signaling pathway in osteogenic differentiation of hBMSCs.These results indicate that BG6Sr cement has a promising combination of physicochemical properties and biological performance for minimally invasive healing of bone defects.

Performance of CH4MOD_(wetland) for the case study of different regions of natural Chinese wetland

Reliable national estimates of CH_4 emissions from natural wetlands depend on model validation based on site observations.We therefore evaluated the performance of the CH_4 MODwetlandmodel in simulating CH_4 emissions from 11 representative wetland sites in five regions of China.Model performance analysis showed that this method effectively simulates differences in the CH_4 fluxes between different sites and regions.The model efficiency for estimating the daily CH_4 fluxes in the northeastern China（NE）,Inner Mongolia and northwestern China（NW）,the North China plain and the Middle-Lower Yangtze Plain（E） and the Qinghai Tibetan Plateau（SW） was 0.51,0.20,0.52 and 0.65,respectively.The efficiency for estimating the annual mean CH_4 fluxes in southern China（S） was 0.99.Systematic negative deviation between the simulated and observed CH_4 emissions existed in all regions,especially in the NW region,which had a mean deviation（RMD） value of-36.7%.On the national scale,the root mean square error（RMSE）,the RMD,the model efficiency（EF）between the simulated and observed seasonal values were 28.7%,-7.8% and 0.93,respectively.The CH_4 emissions showed the highest sensitivity to air temperature in the NE and SW regions,and to water table depth in the E region.Based on the sensitivity analysis,future climate warming and wetting are likely to increase the wetland CH_4 emissions at different levels in all regions of China.

Corrigendum to“Strontium modulates osteogenic activity of bone cement composed of bioactive borosilicate glass particles by activating Wnt/β-catenin signaling pathway”[Bioact.Mater.5(2020)334-347]

The authors regret that the printed version of the above article contained a number of errors which were not identified during the proofing stage.The correct and final version follows.The authors would like to apologies for any inconvenience caused.The authors regret:1.“…and the underlying molecular mechanism of this simulation is yet to be determined”,Page 335,needs to be corrected to“and the underlying molecular mechanism of this stimulation is yet to be determined”.