The neuroimmune pathway of high-altitude adaptation: influence of erythrocytes on attention networks through inflammation and the autonomic nervous system.

Introduction: Many studies have shown that the functional adaptation of immigrants to high-altitude is closely related to oxygen transport, inflammatory response and autonomic nervous system. However, it remains unclear how human attention changes in response to hypoxia-induced neurophysiological activity during high-altitude exposure. Methods: In the present study, we analyzed the relationship between hypoxic-induced neurophysiological responses and attention networks in 116 immigrants (3,680 m) using an attention network test to simultaneously record electroencephalogram and electrocardiogram in combination with specific routine blood markers. Results: Our analysis revealed that red blood cells exert an indirect influence on the three attention networks, mediated through inflammatory processes and heart rate variability. Discussion: The present study provides experimental evidence for the role of a neuroimmune pathway in determining human attention performance at high- altitude. Our findings have implications for understanding the complex interactions between physiological and neurocognitive processes in immigrants adapting to hypoxic environments.

Effects of Vegetation Restoration on Soil Nitrogen Fractions and Enzyme Activities in Arable Land on Purple Soil Slopes.

Purple soils are greatly representative of ecologically fragile soils in southern China, yet the impact of vegetation restoration processes on the nitrogen (N) availability in purple soil ecosystems is still unclear. In this study, the soil nutrient content, available N fractions (including microbial biomass N (MBN), ammonium N (NH4+-N), nitrate N (NO3--N), and total dissolved N (TDN)), and enzyme activities (including urease (URE), nitrate reductase (NR), and nitrite reductase (NIR)) involved in N mineralization and immobilization were investigated across the three vegetation-restoration measures: Camellia oleifera monoculture, Camellia oleifera ryegrass intercropping, and Camellia oleifera intercropping with weeds. The results showed that the Camellia oleifera monoculture mode considerably enhanced the accumulation and availability of soil N and modified the proportion of available N fractions in arable land situated on purple soil slopes, compared to the intercropping mode, the physical, chemical, and microbiological properties of soil demonstrated more pronounced effects due to the Camellia oleifera monoculture vegetation-restoration measures. However, soil nutrient loss is faster on set-aside land and in crop monocultures, and intercropping restoration measures are more beneficial for soil and water conservation under timely fertilization conditions. The soil URE, NR, and NIR activities and MBN content in the Camellia oleifera monoculture model were significantly higher than in the control check sample. Soil N transformation occurs through the combined influence of chemical and biological processes. The relationships between the activities of the three soil enzymes studied and the contents of various components of soil nutrients and effective N displayed significant differences. Notably, URE had a highly significant positive correlation with TOC. There is a strong positive correlation between NR and TN, NIR and TDN, NO3--N, and NH4+-N. Our findings suggest that vegetation restoration improved the soil N availability and its enzyme activities in purple soils, making an essential contribution to the restoration and sustainability of purple soil ecosystem functions.

Soil Nutrients, Enzyme Activities, and Microbial Communities along a Chronosequence of Chinese Fir Plantations in Subtropical China.

Forests undergo a long-term development process from young to mature stages, yet the variations in soil nutrients, enzyme activities, microbial diversity, and community composition related to forest ages are still unclear. In this study, the characteristics of soil bacterial and fungal communities with their corresponding soil environmental factors in the young, middle, and mature stages (7, 15, and 25-year-old) of Chinese fir plantations (CFP) in the subtropical region of China were investigated in 2021. Results showed that the alpha diversity indices (Chao1 and Shannon) of soil bacteria and fungi were higher in 15 and 25-year-old stands than in 7-year-old stand of CFP, while the soil pH, soil water content, soil organic carbon, total nitrogen, total phosphorus, sucrase, urease, acid phosphatase, catalase, and microbial biomass carbon, nitrogen, and phosphorus showed higher in 7-year-old stand than other two stands of CFP. The nonmetric multidimensional scaling analysis revealed that the soil microbial species composition was significantly different in three stand ages of CFP. The redundancy and canonical correspondence analysis indicated that the soil urease and microbial biomass nitrogen were the main factors affecting soil bacterial and fungal species composition. Our findings suggested that soil microbial diversity and community structure were inconsistent with changes in soil nutrients and enzyme activities during CFP development, and enhancing stand nurturing and soil nutrient accumulation in the mid-development stage were beneficial to the sustainable management of CFP.

Neurodynamics of Awareness Detection in Tibetan Immigrants: Evidence from Electroencephalography Analysis.

The psychological effects of long-term exposure to high-altitude environments have attracted great attention. These effects are usually attributed to the diminished cognitive resources due to high-altitude exposure. This study employed electroencephalography (EEG) to investigate the effects of exposure duration on awareness detection tasks. Neither reaction time nor accuracy showed the direct effects of the exposure duration, so did the model indexes obtained from drift diffusion model analysis. However, event-related potentials (ERP) analysis revealed that exposure duration was associated with changes in the visual awareness negativity (VAN) and the late positivity (LP) components, which in turn affected reaction time. Specifically, longer exposure durations were associated with lower VAN and higher LP, resulting in shorter reaction times and greater drift rate. In contrast to previous studies, the reverse relationship between VAN and LP may reflect a compensatory response to the reduced cognitive resources caused by high-altitude exposure. Additionally, increased LP and shorter reaction times with exposure duration may reflect a resistance to the high-altitude environment. We also conducted time-frequency analysis and found that theta power did not vary with exposure duration, suggesting that the reduction in cognitive resources remains stable in these individuals over time. Overall, our study provides new insights into the dynamic effects of high-altitude environments on awareness detection in the presence of reduced cognitive resources.

Association between the acceleration of access to visual awareness of grating orientation with higher heart rate at high-altitude.

Many studies have indicated a strong relationship between cardiac and brain activities, both of which are sensitive to high-altitude exposure. This study combined a consciousness access task and electrocardiograms (ECG) to uncover conscious awareness in response to high-altitude exposure and its relation to cardiac activity. When compared with the low-altitude groups, the behavioral results showed that the high-altitude participants shortened the time of access to visual awareness of grating orientation, which was accompanied by a faster heart rate, excluding the influence of pre-stimulus heart rate, extent of cardiac deceleration after presenting the stimulus, and task difficulty. Although there were post-stimulation cardiac deceleration and post-response acceleration at both high and low altitudes, a slight increase in heart rate after stimulation at high altitudes may indicate that participants at high altitudes could quickly readjust their attention to the target stimulus. More importantly, the drift diffusion model (DDM) was used to fit the access time distribution of all participants. These results suggest that shorter time at high altitudes might be due to the lower threshold, suggesting that less evidence in high-altitude participants was required to access visual consciousness. The participants' heart rates also negatively predicted the threshold through a hierarchical drift diffusion modeling (HDDM) regression. These findings imply that individuals with higher heart rates at high altitudes have a greater cognitive burden.

Altered resting-state network connectivity patterns for predicting attentional function in deaf individuals: An EEG study.

Multiple aspects of brain development are influenced by early sensory loss such as deafness. Despite growing evidence of changes in attentional functions for prelingual profoundly deaf, the brain mechanisms underlying these attentional changes remain unclear. This study investigated the relationships between differential attention and the resting-state brain network difference in deaf individuals from the perspective of brain network connectivity. We recruited 36 deaf individuals and 34 healthy controls (HC). We recorded each participant's resting-state electroencephalogram (EEG) and the event-related potential (ERP) data from the Attention Network Test (ANT). The coherence (COH) method and graph theory were used to build brain networks and analyze network connectivity. First, the ERPs of analysis in task states were investigated. Then, we correlated the topological properties of the network functional connectivity with the ERPs. The results revealed a significant correlation between frontal-occipital connection in the resting state and the amplitude of alert N1 amplitude in the alpha band. Specifically, clustering coefficients and global and local efficiency correlate negatively with alert N1 amplitude, whereas the characteristic path length positively correlates with alert N1 amplitude. In addition, deaf individuals exhibited weaker frontal-occipital connections compared to the HC group. In executive control, the deaf group had longer reaction times and larger P3 amplitudes. However, the orienting function did not significantly differ from the HC group. Finally, the alert N1 amplitude in the ANT task for deaf individuals was predicted using a multiple linear regression model based on resting-state EEG network properties. Our results suggest that deafness affects the performance of alerting and executive control while orienting functions develop similarly to hearing individuals. Furthermore, weakened frontal-occipital connections in the deaf brain are a fundamental cause of altered alerting functions in the deaf. These results reveal important effects of brain networks on attentional function from the perspective of brain connections and provide potential physiological biomarkers to predicting attention.

Changes in Hippocampus and Amygdala Volume with Hypoxic Stress Related to Cardiorespiratory Fitness under a High-Altitude Environment.

The morphology of the hippocampus and amygdala can be significantly affected by a long-term hypoxia-induced inflammatory response. Cardiorespiratory fitness (CRF) has a significant effect on the neuroplasticity of the hippocampus and amygdala by countering inflammation. However, the role of CRF is still largely unclear at high altitudes. Here, we investigated brain limbic volumes in participants who had experienced long-term hypoxia exposure in Tibet (3680 m), utilizing high-resolution structural images to allow the segmentation of the hippocampus and amygdala into their constituent substructures. We recruited a total of 48 participants (48 males; aged = 20.92 ± 1.03 years) to undergo a structural 3T MRI, and the levels of maximal oxygen uptake (VO2max) were measured using a cardiorespiratory function test. Inflammatory biomarkers were also collected. The participants were divided into two groups according to the levels of median VO2max, and the analysis showed that the morphological indexes of subfields of the hippocampus and amygdala of the lower CRF group were decreased when compared with the higher CRF group. Furthermore, the multiple linear regression analysis showed that there was a higher association with inflammatory factors in the lower CRF group than that in the higher CRF group. This study suggested a significant association of CRF with hippocampus and amygdala volume, which may be related to hypoxic stress in high-altitude environments. A better CRF reduced physiological stress and a decrease in the inflammatory response was observed, which may be related to the increased oxygen transport capacity of the body.

Response of soil microbial community to plant composition changes in broad-leaved forests of the karst area in Mid-Subtropical China.

The rapid growth and expansion ofCryptomeria japonica (Thunb. ex L. f.) D. Don in karst area strongly affects plant composition of native deciduous broad-leaved forest, which seriously threat ecosystem function and service. Given the importance of soil microorganisms in regulating nutrients cycling and plant species coexistence, understanding soil microbial attributes and their relationships with soil and vegetation features in forests harboring different C. japonica abundance will help understanding the drivers of ecosystem function changes. Here we examined the diversity and composition of soil bacterial and fungal communities and their correlations with plant diversity as well as soil physicochemical properties in karst broad-leaved forests with different relative abundances of C. japonica (i.e., a high, moderate, low and no proportion level with a stem density of 1,487, 538, 156 and 0 plant/hm2, respectively) in Mid-Subtropical China. We found that soil pH decreased while soil water content (SWC), total nitrogen (TN), total phosphorus (TP) and total potassium (TK) tended to increase with the increase in C. japonica abundance. In contrast, soil available nitrogen (AN), available phosphorus (AP) and available potassium (AK) content declined by 26.1%∼49.3% under the high level of C. japonica abundance. A gradual decrease in relative abundance of Acidobacteria and Chloroflexi while a pronounced increase in relative abundance of Ascomycota and Basidiomycota were observed with increase of C. japonica abundance. Alternations in bacterial composition were closely related to changes in AP and AK, while the change of fungal structure was mainly related to SWC, soil organic carbon (SOC) and pH, indicating that bacterial community was sensitive to declines in soil available nutrients and fungal structure was sensitive to changes in soil physicochemical properties (i.e., pH and SWC) and organic carbon resource. Understory plants had the highest α-diversity in forest containing moderate abundance of C. japonica, which might be related to the high bacterial diversity. Our findings suggest conservation of soil bacterial and fungal taxa that are responsible for nutrients availability and carbon sequestration is of great significance for improving the resistance of natural deciduous broad-leaved forests to the rapid spread of C. japonica in karst areas. Moreover, Acidobacteria, Chloroflexi, Ascomycota and Basidiomycota are potential indicators for soil properties changes, which should be taken into consideration in karst forest managements.

Oxygen Metabolism-induced Stress Response Underlies Heart-brain Interaction Governing Human Consciousness-breaking and Attention.

Neuroscientists have emphasized visceral influences on consciousness and attention, but the potential neurophysiological pathways remain under exploration. Here, we found two neurophysiological pathways of heart-brain interaction based on the relationship between oxygen-transport by red blood cells (RBCs) and consciousness/attention. To this end, we collected a dataset based on the routine physical examination, the breaking continuous flash suppression (b-CFS) paradigm, and an attention network test (ANT) in 140 immigrants under the hypoxic Tibetan environment. We combined electroencephalography and multilevel mediation analysis to investigate the relationship between RBC properties and consciousness/attention. The results showed that RBC function, via two independent neurophysiological pathways, not only triggered interoceptive re-representations in the insula and awareness connected to orienting attention but also induced an immune response corresponding to consciousness and executive control. Importantly, consciousness played a fundamental role in executive function which might be associated with the level of perceived stress. These results indicated the important role of oxygen-transport in heart-brain interactions, in which the related stress response affected consciousness and executive control. The findings provide new insights into the neurophysiological schema of heart-brain interactions.

Fault severity assessment of rolling bearing based on optimized multi-dictionaries matching pursuit and Lempel-Ziv complexity.

For the safe working of rolling bearing, this paper presents a fault severity assessment method through optimized multi-dictionaries matching pursuit (OMMP) and Lempel-Ziv (LZ) complexity. To solve the redundancy problem of over-complete dictionary, the OMMP is proposed by introducing the quantum particle swarm optimization into matching pursuit for best representing the original vibration signal. And then, LZ complexity is calculated as an index of fault severity assessment by reconstructed signal. The performance of assessment method is verified through the measured signals of three bearing tests, and the comparisons with various methods are specifically described. The results indicate that the OMMP method averagely takes the shortest running time for the vibration signal decomposition. The assessment method is able to effectively evaluate different fault sizes of rolling bearing, and has a great applicability to in the condition-based maintenance of rotating machineries.

X-ray-based positioning method for mars entry blackout mitigation.

Enhancing the positional information acquisition during Mars entry blackout improves the Mars landing mission reliability. A positioning method based on the high-penetration of X-rays was developed to solve the problem. The X-ray signal attenuation was estimated. The positioning performance and the influence of X-ray signal transmission system were also evaluated. Results indicated that the X-ray signal attenuation is extremely low, and the X-ray-based method is expected to be a potential application for obtaining high-precision positional information during Mars entry blackout.

High penetration X-ray communication under physical shielding.

BACKGROUND: Modern industrial facilities urgently need effective wireless communication technology to monitor instruments and equipment, but electromagnetic interference and physical shielding often exist in these fields, thereby preventing traditional communication methods from working correctly. OBJECTIVE: As a special wireless optical communication technology, X-ray communication (XCOM) is expected to solve the problem of signal transmission under this extreme condition. Our goal was to prove the feasibility of XCOM for signal transmission under metal barrier condition. METHODS: The Monte Carlo method was used to simulate the transmission characteristics of X-ray beam under metal barrier conditions, and the communication performance of XCOM was evaluated. Moreover, the experimental demonstration system of XCOM was developed to test the penetration and communication performance of XCOM under metal shield. RESULTS: X-ray with energy above 150 keV could achieve a bit error rate of less than 10-4 after passing through a 20 mm iron, whereas X-ray with energy above 250 keV could maintain excellent communication performance after passing through a 30 mm iron. The experimental test results were consistent with the theoretical calculation. CONCLUSIONS: As a new wireless optical communication technology, X-ray communication is expected to solve the problem of signal transmission under physical shielding conditions.

Paracrine Interactions Involved in Human Induced Pluripotent Stem Cells Differentiation into Chondrocytes.

Osteoarthritis (OA), as a degenerative joint disease, is the most common form of joint disorder that causes pain, stiffness, and other symptoms associated with OA. Various genetic, biomechanical, and environmental factors have a relevant role in the development of OA. To date, extensive efforts are currently being made to overcome the poor self-healing capacity of articular cartilage. Despite the pivotal role of chondrocytes, their proliferation and repair capacity after tissue injury are limited. Therefore, the development of new strategies to overcome these constraints is urgently needed. Recent advances in regenerative medicine suggest that pluripotent stem cells are promising stem cell sources for cartilage repair. Pluripotent stem cells are undifferentiated cells that have the capacity to differentiate into different types of cells and can self-renew indefinitely. In the past few decades, numerous attempts have been made to regenerate articular cartilage by using induced pluripotent stem cells (iPSCs). The potential applications of patient-specific iPSCs hold great promise for regenerative medicine and OA treatment. However, there are different culture conditions for the preparation and characterization of human iPSCs-derived chondrocytes (hiChondrocytes). Recent biochemical analyses reported that several paracrine factors such as TGFb, BMPs, WNT, Ihh, and Runx have been shown to be involved in cartilage cell proliferation and differentiation from human iPSCs. In this review, we summarize and discuss the paracrine interactions involved in human iPSCs differentiation into chondrocytes in different cell culture media.

Effects of thinning intensity on understory vegetation and soil microbial communities of a mature Chinese pine plantation in the Loess Plateau.

Thinning can effectively improve forest production and maintain ecological stability. However, the changes in soil microbial community compositions after thinning are still not well understood. In this study, we investigated the changes in the soil microbial community of mature Chinese pine (Pinus tabuliformis) plantations in the Loess Plateau after 11years of four different thinning intensity treatments. Furthermore, the responses of the soil microbial community to changes in understory plants and soil properties were analyzed. The ratios of wood removal investigated were 0 (CK), 15% (LIT), 30% (MIT) and 45% (HIT). Compared with the CK, thinning significantly increased the Shannon index, species richness, coverage and biomass of the understory plants, and these values were highest for the HIT. The soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), nitrate nitrogen (NO3--N) and available phosphorus (AP) concentrations increased with increasing thinning intensity. Thinning intensity did not significantly affect soil microbial community diversity indices. With respect to the dominant bacterial groups, the relative abundance of Proteobacteria was much higher in the HIT, while that of Acidobacteria was much higher in the LIT and CK. For the dominant fungal groups, the relative abundance of Basidiomycota was lowest in the HIT, while that of Ascomycota was highest in the same treatment. Redundancy analysis (RDA) showed that SOC, TN, and AP significantly correlated with soil bacterial communities and that SOC, TN, TP, AP and NO3--N significantly correlated with soil fungal communities. The understory vegetation influenced soil fungal communities rather than soil bacterial communities. These findings suggest that the aboveground vegetation diversity and soil nutrients were improved with the increased thinning intensity after 11years. The copiotrophic groups (e.g. Proteobacteria) and oligotrophic groups (e.g. Acidobacteria) differed significantly among the four thinning treatments, indicating a dependence of the soil microbial community composition on soil nutrients.

Effects of stand age and soil properties on soil bacterial and fungal community composition in Chinese pine plantations on the Loess Plateau.

The effects of Chinese pine (Pinus tabuliformis) on soil variables after afforestation have been established, but microbial community changes still need to be explored. Using high-throughput sequencing technology, we analyzed bacterial and fungal community composition and diversity in soils from three stands of different-aged, designated 12-year-old (PF1), 29-year-old (PF2), and 53-year-old (PF3), on a Chinese pine plantation and from a natural secondary forest (NSF) stand that was almost 80 years old. Abandoned farmland (BL) was also analyzed. Shannon index values of both bacterial and fungal community in PF1 were greater than those in PF2, PF3 and NSF. Proteobacteria had the lowest abundance in BL, and the abundance increased with stand age. The abundance of Actinobacteria was greater in BL and PF1 soils than those in other sites. Among fungal communities, the dominant taxa were Ascomycota in BL and PF1 and Basidiomycota in PF2, PF3 and NSF, which reflected the successional patterns of fungal communities during the development of Chinese pine plantations. Therefore, the diversity and dominant taxa of soil microbial community in stands 12 and 29 years of age appear to have undergone significant changes; afterward, the soil microbial community achieved a relatively stable state. Furthermore, the abundances of the most dominant bacterial and fungal communities correlated significantly with organic C, total N, C:N, available N, and available P, indicating the dependence of these microbes on soil nutrients. Overall, our findings suggest that the large changes in the soil microbial community structure of Chinese pine plantation forests may be attributed to the phyla present (e.g., Proteobacteria, Actinobacteria, Ascomycota and Basidiomycota) which were affected by soil carbon and nutrients in the Loess Plateau.