Nitrogen addition delays the emergence of an aridity-induced threshold for plant biomass

Crossing certain aridity thresholds in global drylands can lead to abrupt decays of ecosystem attributes such as plant productivity, potentially causing land degradation and desertification. It is largely unknown, however, whether these thresholds can be altered by other key global change drivers known to affect the water-use efficiency and productivity of vegetation, such as elevated CO2 and nitrogen (N). Using >5000 empirical measurements of plant biomass, we showed that crossing an aridity (1–precipitation/potential evapotranspiration) threshold of ∼0.50, which marks the transition from dry sub-humid to semi-arid climates, led to abrupt declines in aboveground biomass (AGB) and progressive increases in root:shoot ratios, thus importantly affecting carbon stocks and their distribution. N addition significantly increased AGB and delayed the emergence of its aridity threshold from 0.49 to 0.55 (P < 0.05). By coupling remote sensing estimates of leaf area index with simulations from multiple models, we found that CO2 enrichment did not alter the observed aridity threshold. By 2100, and under the RCP 8.5 scenario, we forecast a 0.3% net increase in the global land area exceeding the aridity threshold detected under a scenario that includes N deposition, in comparison to a 2.9% net increase if the N effect is not considered. Our study thus indicates that N addition could mitigate to a great extent the negative impact of increasing aridity on plant biomass in drylands. These findings are critical for improving forecasts of abrupt vegetation changes in response to ongoing global environmental change.This research was supported by the Second Tibetan Plateau Scientific Expedition and Research (2019QZKK0305), the Fundamental Research Funds for the Central Universities (lzujbky-2022-ct01), "111" Project (BP0719040) and "Innovation Star" project of Gansu Province's outstanding graduate students in 2023 (2023CXZX-132). FTM is supported by Generalitat Valenciana (CIDEGENT/2018/041) and the Spanish Ministry of Science and Innovation (EUR2022-134048). ZZ is supported by the National Natural Science Foundation of China (41901122) and the Shenzhen Fundamental Research Program (GXWD20201231165807007- 20200814213435001). JP is supported by the Spanish Government grant TED2021-132627B-I00 funded by MCIN, AEI/10.13039/501100011033 and the European Union NextGenerationEU/PRTR, the Fundación Ramón Areces grant CIVP20A6621, and the Catalan Government grant SGR2021-1333

Structural Parameter Sensitivity Analysis of an Aircraft Anti-Icing Cavity Based on Thermal Efficiency

The objective of this paper is to accurately describe the influence of structural parameter uncertainties on the thermal efficiency of an aircraft wing anti-icing cavity. To do this, a new method of parameter sensitivity evaluation is proposed according to the weighted stochastic response surface method. First, the concept of fitting the explicit performance function of the anti-icing cavity structure using the weighted stochastic response surface method is presented. A structural parameter sensitivity analysis based on thermal efficiency is then conducted considering the uncertainties of the position of the flute tube, the height of the double-skin channel, and the diameter and angle of the jet holes. The results indicate that the height of the double-skin channel and the diameter of the jet holes are the main factors influencing the functional reliability of the anti-icing cavity

A Semi-supervised Learning Application for Hand Posture Classification

The rapid growth of HCI applications results in increased data size and complexity. For this, advanced machine learning techniques and data analysis solutions are used to prepare and process data patterns. However, the cost of data pre-processing, labelling, and classification can be significantly increased if the dataset is huge, complex, and unlabelled. This paper aims to propose a data pre-processing approach and semi-supervised learning technique to prepare and classify a big Motion Capture Hand Postures dataset. It builds the solutions via Tri-training and Co-forest techniques and compares them to figure out the best-fitted approach for hand posture classification. According to the results, Co-forest outperforms Tri-training in terms of Accuracy, Precision, recall, and F1-score

The global biogeography of soil priming effect intensity

9 páginas.- 4 figuras.- 41 referencias.- Additional supporting information may be found in the online version of the article at the publisher’s website.-Aim Fresh carbon (C) inputs to the soil can have important consequences for the decomposition rates of soil organic matter (priming effect), thereby impacting the delicate global C balance at the soil-atmosphere interface. Yet, the environmental factors that control soil priming effect intensity remain poorly understood at a global scale. Location Global. Time period 1980-2020. Major taxa studied Soil priming effect intensity. Methods We conducted a global dataset of CO2 effluxes in 711 pairwise soils with C-13 or C-14 simple C sources inputs and without C inputs from incubation experiments in which isotope-labelled C was used to quantify fresh C-induced rather than exudate-induced priming. Results Soil priming effect intensity is predominantly positive. Soil texture and C content were identified as the most important factors associated with priming effects, with sandy soils from tropical and mid-latitudes supporting the highest soil priming effect intensity, and soils with greater C content and fine textures from high latitudes maintaining the lowest soil priming effects. The negative association between C content and soil priming effect intensity was also indirectly driven by changing mean annual temperature, net primary productivity, and fungi : bacteria ratio. Using this information, we generated a global map of soil priming effect intensity, and found that the priming was lower at high latitudes and higher at lower latitudes. Main conclusions Global patterns of soil priming effect intensity can be predicted using environmental data, with soil texture and C content playing a predominant role in explaining in priming effects. These effects were also indirectly driven by climate, vegetation and soil microbial properties. We present the first global atlas of soil priming effect intensity and advance our knowledge on the potential mechanisms underlying soil priming effect intensity, which are integral to improving the climate change and soil C dynamics components of Earth System models.National Natural Science Foundation of China, Grant/Award Number: 41907031; China Postdoctoral Science Foundation, Grant/Award Number: 2021T140565; Natural Science Basic Research Plan in Shaanxi Province of China, Grant/Award Number: 2020JQ-272; Forest and Grass Technology Innovation Development and Research Projects from National Forestry and Grassland Administration, Grant/Award Number: 2020132111; China Postdoctoral Science Foundation, Grant/Award Number: 2019M650276; Chinese Academy of Sciences “Light of West China” Program for Introduced Talent in the West, Grant/Award Number: 31570440Peer reviewe

Basic Study for Ultrasound-Based Navigation for Pedicle Screw Insertion Using Transmission and Backscattered Methods

<div><p>The purpose of this study was to understand the acoustic properties of human vertebral cancellous bone and to study the feasibility of ultrasound-based navigation for posterior pedicle screw fixation in spinal fusion surgery. Fourteen human vertebral specimens were disarticulated from seven un-embalmed cadavers (four males, three females, 73.14 ± 9.87 years, two specimens from each cadaver). Seven specimens were used to measure the transmission, including tests of attenuation and phase velocity, while the other seven specimens were used for backscattered measurements to inspect the depth of penetration and A-Mode signals. Five pairs of unfocused broadband ultrasonic transducers were used for the detection, with center frequencies of 0.5 MHz, 1 MHz, 1.5 MHz, 2.25 MHz, and 3.5 MHz. As a result, good and stable results were documented. With increased frequency, the attenuation increased (<i>P</i><0.05), stability of the speed of sound improved (<i>P</i><0.05), and penetration distance decreased (<i>P</i>>0.05). At about 0.6 cm away from the cortical bone, warning signals were easily observed from the backscattered measurements. In conclusion, the ultrasonic system proved to be an effective, moveable, and real-time imaging navigation system. However, how ultrasonic navigation will benefit pedicle screw insertion in spinal surgery needs to be determined. Therefore, ultrasound-guided pedicle screw implantation is theoretically effective and promising.</p></div

A-Mode Signal in Backscattering Measurements.

<p>Normalized amplitude at different specimen thicknesses for the 5 transducers was exhibited. The amplitude increased significantly when the thickness of the specimens reduced to about 0.6 cm.</p

Ultrasound Attenuation of the Seven Specimens.

<p>For the same specimen, the ultrasound attenuation increased while the amplitude decreased with an increase in the frequency.</p