The uncertainty analysis of the MODIS GPP product in global maize croplands

Gross primary productivity (GPP) is very important in the global carbon cycle. Currently, the newly released estimates of 8-day GPP at 500 m spatial resolution (Collection 6) are provided by the Moderate Resolution Imaging Spectroradiometer (MODIS) Land Science Team for the global land surface via the improved light use efficiency (LUE) model. However, few studies have evaluated its performance. In this study, the MODIS GPP products (GPPMOD) were compared with the observed GPP (GPPEC) values from site-level eddy covariance measurements over seven maize flux sites in different areas around the world. The results indicate that the annual GPPMOD was underestimated by 6%‒58% across sites. Nevertheless, after incorporating the parameters of the calibrated LUE, the measurements of meteorological variables and the reconstructed Fractional Photosynthetic Active Radiation (FPAR) into the GPPMOD algorithm in steps, the accuracies of GPPMOD estimates were improved greatly, albeit to varying degrees. The differences between the GPPMOD and the GPPEC were primarily due to the magnitude of LUE and FPAR. The underestimate of maize cropland LUE was a widespread problem which exerted the largest impact on the GPPMOD algorithm. In American and European sites, the performance of the FPAR exhibited distinct differences in capturing vegetation GPP during the growing season due to the canopy heterogeneity. In addition, at the DE-Kli site, the GPPMOD abruptly produced extreme low values during the growing season because of the contaminated FPAR from a continuous rainy season. After correcting the noise of the FPAR, the accuracy of the GPPMOD was improved by approximately 14%. Therefore, it is crucial to further improve the accuracy of global GPPMOD, especially for the maize crop ecosystem, to maintain food security and better understand global carbon cycle

A study of instability in a miniature flying-wing aircraft in high-speed taxi

AbstractThis study investigates an instability that was observed during high-speed taxi tests of an experimental flying-wing aircraft. In order to resolve the reason of instability and probable solution of it, the instability was reproduced in simulations. An analysis revealed the unique stability characteristics of this aircraft. This aircraft has a rigid connection between the nose wheel steering mechanism and an electric servo, which is different from aircraft with a conventional tricycle landing gear system. The analysis based on simulation results suggests that there are two reasons for the instability. The first reason is a reversal of the lateral velocity of the nose wheel. The second reason is that the moment about the center of gravity created by the lateral friction force from the nose wheel is larger than that from the lateral friction force from the main wheels. These problems were corrected by changing the ground pitch angle. Simulations show that reducing the ground pitch angle can eliminate the instability in high-speed taxi

A review of research on acoustic detection of heat exchanger tube

Leakage in heat exchanger tubes can result in unreliable products and dangerous situations, which could cause great economic losses. Along with fast development of modern acoustic detection technology, using acoustic signals to detect leakage in heat exchange tube has been gradually accepted and considered with great potential by both industrial and research societies. In order to further advance the development of acoustic signal detection technology and investigate better methods for leakage detection in heat exchange tube, in this paper, firstly, we conduct a short overview of the theory of acoustic signal detection on heat exchanger tube, which had already been continuously developed for a few decades by researchers worldwide. Thereafter, we further expound the advantages and limitations of acoustic signal detection technology on heat exchanger tube in four aspects: 1) principles of acoustic signal detection, 2) characteristics of sound wave propagation in heat exchanger tube, 3) methods of leakage detection, and 4) leakage localization in heat exchanger tube

PeP: a Point enhanced Painting method for unified point cloud tasks

Point encoder is of vital importance for point cloud recognition. As the very beginning step of whole model pipeline, adding features from diverse sources and providing stronger feature encoding mechanism would provide better input for downstream modules. In our work, we proposed a novel PeP module to tackle above issue. PeP contains two main parts, a refined point painting method and a LM-based point encoder. Experiments results on the nuScenes and KITTI datasets validate the superior performance of our PeP. The advantages leads to strong performance on both semantic segmentation and object detection, in both lidar and multi-modal settings. Notably, our PeP module is model agnostic and plug-and-play. Our code will be publicly available soon

The Role of Butyric Acid in Treatment Response in Drug-Naive First Episode Schizophrenia

Background: Butyric acid, a major short-chain fatty acid (SCFA), has an important role in the microbiota-gut-brain axis and brain function. This study investigated the role of butyric acid in treatment response in drug-naive first episode schizophrenia. Methods: The study recruited 56 Chinese Han schizophrenia inpatients with normal body weight and 35 healthy controls. Serum levels of butyric acid were measured using Gas Chromatography-Mass Spectrometer (GC-MS) analysis at baseline (for all participants) and 24 weeks after risperidone treatment (for patients). Clinical symptoms were measured using the Positive and Negative Syndrome Scale (PANSS) for patients at both time points. Results: At baseline, there was no significant difference in serum levels of butyric acid between patients and healthy controls (p = 0.206). However, there was a significant increase in serum levels of butyric acid in schizophrenia patients after 24-week risperidone treatment (p = 0.030). The PANSS total and subscale scores were decreased significantly after 24-week risperidone treatment (p\u27s \u3c 0.001). There were positive associations between baseline serum levels of butyric acid and the reduction ratio of the PANSS total and subscale scores after controlling for age, sex, education, and duration of illness (p\u27s \u3c 0.05). Further, there was a positive association between the increase in serum levels of butyric acid and the reduction of the PANSS positive symptoms subscale scores (r = 0.38, p = 0.019) after controlling for potential confounding factors. Conclusions: Increased serum levels of butyric acid might be associated with a favorable treatment response in drug-naive, first episode schizophrenia. The clinical implications of our findings were discussed

A novel distance learning for elastic cross-modal audio-visual matching

In this work we propose a novel network formulation for joint representation of cross-modal audio and visual information base on metric learning. We employ a distance learning framework as a training procedure. For this purpose we introduce an elastic matching network (EmNet) and a novel loss function to learn the shared latent space representation of multi-modal information. The elastic matching network is capable of matching given face image (or audio voice clip) from diverse number of audio clips (or face images). We quantitatively and qualitatively evaluate the purposed approach on the standard audio-visual matching evaluation dataset, the overlap of VoxCeleb and VGGFace by both multi-way and binary audio-visual matching tasks. The promising performance comparing to the existing methods verifies the effectiveness of the proposed approach, which yields to a new state-of-the-art for cross-modal audio-visual matching

Staged open reduction and internal fixation with double-locking plates to treat bilateral distal femur periprosthetic fractures after total knee arthroplasty: A case report

BackgroundThe incidence of periprosthetic fractures after total knee arthroplasty (TKA) increases in parallel with the number of procedures. Comminuted fractures along the primary fracture line extending to the edge of the prosthesis are challenging, and bilateral fractures are rarely reported, especially with open injuries.Case presentationA 65-year-old female had undergone bilateral TKA in our hospital 5 years before admission. She was admitted with a traumatic bilateral Rorabeck type II B distal femur periprosthetic fracture (closed right, open left, Gustilo II) and was treated with bilateral staged open reduction and internal fixation (ORIF) with double-locking plates. The patient experienced a prolonged delayed fracture union and finally healed around 21 months postoperatively. The function was satisfactory after 4 years of follow-up.ConclusionORIF with double-locking plates can be used to treat Rorabeck II B periprosthetic fracture where the primary fracture line extends beyond the edge of the prosthesis; however, there may be delayed healing or nonunion. Patients need to undergo long-term rehabilitation and endure long disability times and require good rehabilitation nursing care. Once they achieve bone healing, the treatment achieves bone preservation and substantial prosthesis survival

Dissolved nutrient distributions in the Antarctic Cosmonaut Sea in austral summer 2021

Dissolved nutrients are essential to marine productivity and ecosystem structures in the Southern Ocean. The spatial distributions of dissolved nutrients in the Cosmonaut Sea were studied during the 37th Chinese National Antarctic Research Expedition in 2021. The relative standard deviations of the nitrate (NO3-N), nitrite (NO2-N), ammonium (NH4-N), phosphate (PO4-P), and silicate (SiO3-Si) concentrations found in duplicate samples (n=2) were 1.01%, 9.04%, 6.45%, 0.94%, and 0.67%, respectively. The mean NO3-N, NO2-N, NH4-N, PO4-P, and SiO3-Si concentrations in the mixed layer were 26.41±4.13, 0.15±0.09, 0.51±0.22, 1.73±0.23, and 41.48±6.94 μmol·L−1, respectively, and were higher than the relevant limitation concentrations. The concentrations were generally bounded horizontally by the Southern Boundary (SB) of the Antarctic Circumpolar Current, the NO3-N, NO2-N, NH4-N, and PO4-P concentrations being higher northeast than southwest of the SB but the SiO3-Si concentrations being higher southwest than northeast, indicating that the SB dominates nutrient distributions in the mixed layer. The NO3-N, NH4-N, and PO4-P concentrations gradually increased moving vertically down from the mixed layer to 200 m deep and then remained at 33.73±3.51, 0.26±0.13, and 2.28±0.10 μmol·L−1, respectively, to the bottom. The SiO3-Si concentration increased as depth increased and reached a maximum in the bottom layer. The NO2-N concentration decreased rapidly as depth increased and was ~0 μmol·L−1 at >150 m deep. Circumpolar Deep Water upwelling may cause high nutrient concentrations in shallower layers up to the 100 m layer between 62.5°S and 64°S