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Permafrost has been warming and thawing globally, with subsequent effects on the climate, hydrology, and the ecosystem. However, the permafrost thermal state variation in the northern lower limit of the permafrost zone (Xidatan) on the Qinghai–Tibet Plateau (QTP) is unclear. This study attempts to explore the changes and variability in this permafrost using historical (1970–2019) and future projection datasets from remote-sensing-based land surface temperature product (LST) and climate projections from Earth system model (ESM) outputs of the Coupled Model Intercomparison Project Phase 5 and 6 (CMIP5, CMIP6). Our model considers phase-change processes of soil pore water, thermal-property differences between frozen and unfrozen soil, geothermal flux flow, and the ground ice effect. Our model can consistently reproduce the vertical ground temperature profiles and active layer thickness (ALT), recognizing permafrost boundaries, and capture the evolution of the permafrost thermal regime. The spatial distribution of permafrost and its thermal conditions over the study area were controlled by elevation with a strong influence of slope orientation. From 1970 to 2019, the mean annual ground temperature (MAGT) in the region warmed by 0.49 ∘C in the continuous permafrost zone and 0.40 ∘C in the discontinuous permafrost zone. The lowest elevation of the permafrost boundary (on the north-facing slopes) rose approximately 47 m, and the northern boundary of discontinuous permafrost retreated southwards by approximately 1–2 km, while the lowest elevation of the permafrost boundary remained unchanged for the continuous permafrost zone. The warming rate in MAGT is projected to be more pronounced under shared socioeconomic pathways (SSPs) than under representative concentration pathways (RCPs), but there are no distinct discrepancies in the areal extent of the continuous and discontinuous permafrost and seasonally frozen ground among SSP and RCP scenarios. This study highlights the slow delaying process of the response of permafrost in the QTP to a warming climate, especially in terms of the areal extent of permafrost distribution.

Permafrost has been warming and thawing at a global scale with subsequent effects on the climate, hydrological, ecosystem and engineering system. However, the variation of permafrost thermal state in the northern lower limit of the permafrost zone (Xidatan) on the Qinghai–Tibetan Plateau (QTP) is unclear. To evaluate and project the permafrost changes, this study simulated the spatiotemporal dynamics of this marginal permafrost historically (1970–2019) based on the detailed investigation and monitoring datasets from 1987 in this study region, improved remote sensing-based Land Surface Temperature product (LST) and climate projections from Global Climate Model (GCM) outputs of Coupled Model Intercomparison Project Phase 5 and 6 (CMIP5, CMIP6). Our model takes into consideration of phase change processes of soil pore water, thermal property difference between frozen and thawed soil, geothermal flux flow, and ground ice effect. The results indicate that 1) our model can consistently reproduce the ground temperature field and active layer thickness (ALT), is superior in recognizing permafrost boundaries, and would realistically capture the evolution of the permafrost thermal regime, 2) spatial distribution of permafrost and its thermal conditions over the study area were controlled by elevational with a strong influence of slope aspects, 3) from 1970 to 2019, the regional averaged means annual ground temperature (MAGT) had warmed by 0.49 °C in the continuous permafrost zone and 0.40 °C in the discontinuous permafrost zone, and the lowest elevation of permafrost boundary (on north-facing slopes) rose approximately 47 m, as well as the northern boundary of discontinuous permafrost has approximately retreated southwards 1~2 km, while the lowest elevation of permafrost boundary remains unchanged for continuous permafrost zone, 4) the warming rate in MAGT is projected to be slighter higher under Shared Socioeconomic Pathways (SSPs) than that of Representative Concentration Pathways (RCPs), but no distinct discrepancies in the areal extent of the continuous, discontinuous permafrost and seasonally frozen ground among SSP and RCP scenarios. This study highlights the slow delaying process in the response of mountain permafrost to a warming climate, especially in terms of the areal extent of permafrost distribution.

A high frequency periodic signal measurement system based on equivalent sampling method is developed. A high-speed sampling voltage tracking circuit, the core component of the system, is described in detail. The circuit can transform the amplitude corresponding to different phase points of the signal undertest into the equivalent DC level through successive approximation of multiple periods. The measurement system designed in this paper completes digital sampling with high accuracy only by connecting the low-cost voltage tracking circuit to the existing commercial instruments, such as two-channel waveform generator and high-precision digital multimeter, which makes the method easy to be generalized. The special structure of the sampling tracking circuit greatly reduces the influence of random noise and time jitter on the measurement results. The experimental results show that the non-linearity error of the system is as low as 0.002%, the bandwidth can reach 200 MHz, and the uncertainty of measuring the RMS of AC voltage with peak value of ±1 V and frequency of 10 kHz, 100 kHz and 1 MHz can reach 2.8 × 10−4 V, 4.6 × 10−4 V and 2.0 × 10−4 V (k = 2), respectively.

Previous walkability scoring systems are all based on road networks, even though roads are not designed for pedestrians. To calculate an accurate walking score, we need pedestrian network data. This is especially the case in cities such as Hong Kong, where pedestrians are separated from vehicles by footbridges, underpasses or surface sidewalks. In this paper, we investigate why and how a three-dimensional pedestrian network makes a difference in walkability scoring, using Hong Kong as a case city. We developed a walkability scoring system based on networks and amenities, using multiple open-source programming platforms and languages. Separately, we calculated walkability scores (on a scale of 0–100) using the three-dimensional pedestrian network and road network of the city, comparing the differences between the two. A GIS raster analysis was conducted to extract walkability scoring differences from the two walkability surfaces, followed by a univariate linear model to examine how the scores were underestimated if without using the three-dimensional pedestrian network. Results show that streets were considered twice as walkable if rated by pedestrian network rather than road network. Walkability scores were 92% higher on average. The fitted model shows that the mean score underestimations were significantly different for different three-dimensional network elements. Surface sidewalks had an average underestimation of 33.75 (p

Background The inflammation and oxidative stress (OS) have been considered crucial components of the pathogenesis of depression. Edaravone (EDA), a free radical scavenger, processes strong biological activities including antioxidant, anti-inflammatory and neuroprotective properties. However, its role and potential molecular mechanisms in depression remain unclear. The present study aimed to investigate the antidepressant activity of EDA and its underlying mechanisms. Methods A chronic social defeat stress (CSDS) depression model was performed to explore whether EDA could produce antidepressant effects. Behaviors tests were carried out to examine depressive, anxiety-like and cognitive behaviors including social interaction (SI) test, sucrose preference test (SPT), open field test (OFT), elevated plus maze (EPM), novel object recognition (NOR), tail suspension test (TST) and forced swim test (FST). Hippocampal and medial prefrontal cortex (mPFC) tissues were collected for Nissl staining, immunofluorescence, targeted energy metabolomics analysis, enzyme-linked immunosorbent assay (ELISA), measurement of MDA, SOD, GSH, GSH-PX, T-AOC and transmission electron microscopy (TEM). Western blotting (WB) and quantitative real-time polymerase chain reaction (qRT-PCR) detected the Sirt1/Nrf2/HO-1/Gpx4 signaling pathway. EX527, a Sirt1 inhibitor and ML385, a Nrf2 inhibitor were injected intraperitoneally 30 min before EDA injection daily. Knockdown experiments were performed to determine the effects of Gpx4 on CSDS mice with EDA treatment by an adeno-associated virus (AAV) vector containing miRNAi (Gpx4)–EGFP infusion. Results The administrated of EDA dramatically ameliorated CSDS-induced depressive and anxiety-like behaviors. In addition, EDA notably attenuated neuronal loss, microglial activation, astrocyte dysfunction, oxidative stress damage, energy metabolism and pro-inflammatory cytokines activation in the hippocampus (Hip) and mPFC of CSDS-induced mice. Further examination indicated that the application of EDA after the CSDS model significantly increased the protein expressions of Sirt1, Nrf2, HO-1 and Gpx4 in the Hip. EX527 abolished the antidepressant effect of EDA as well as the protein levels of Nrf2, HO-1 and Gpx4. Similarly, ML385 reversed the antidepressant and anxiolytic effects of EDA via decreased expressions of HO-1 and Gpx4. In addition, Gpx4 knockdown in CSDS mice abolished EDA-generated efficacy on depressive and anxiety-like behaviors. Conclusion These findings suggest that EDA possesses potent antidepressant and anxiolytic properties through Sirt1/Nrf2/HO-1/Gpx4 axis and Gpx4-mediated ferroptosis may play a key role in this effect.

This paper examines how mass ridership data can help describe cities from the bikers' perspective. We explore the possibility of using the data to reveal general bikeability patterns in 202 major Chinese cities. This process is conducted by constructing a bikeability rating system, the Mobike Riding Index (MRI), to measure bikeability in terms of usage frequency and the built environment. We first investigated mass ridership data and relevant supporting data; we then established the MRI framework and calculated MRI scores accordingly. This study finds that people tend to ride shared bikes at speeds close to 10 km/h for an average distance of 2 km roughly three times a day. The MRI results show that at the street level, the weekday and weekend MRI distributions are analogous, with an average score of 49.8 (range 0–100). At the township level, high-scoring townships are those close to the city centre; at the city level, the MRI is unevenly distributed, with high-MRI cities along the southern coastline or in the middle inland area. These patterns have policy implications for urban planners and policy-makers. This is the first and largest-scale study to incorporate mobile bike-share data into bikeability measurements, thus laying the groundwork for further research.

Behavior models of electronic components are critical in many metrological and measurement areas, e.g., time-domain simulations for analog-integrated circuit design and predistortion of the amplifier to reduce the distortion. This paper describes the use of pulse-driven ac Josephson voltage standard (ACJVS) to synthesize quantum accurate waveforms with ultralow distortion and noise floor to model the amplifier nonlinearity, which is a promising way to increase the modeling accuracy. Four Volterra series models including the memory polynomial model and three submodels of the dynamic deviation reduction model are analyzed and compared in detail. Normalized mean square error is calculated to evaluate the modeling accuracy. The difference of the measured and predicted outputs of the amplifier are compared in both time and frequency domains. The result shows that high-performance models can be achieved, which demonstrates the feasibility of modeling nonlinear amplifier behavior with the ACJVS.

After continuous investigation on the electrical compensation method for the end effect error in the new vertical calculable cross-capacitor (VCCC), the latest optimal hollow active auxiliary electrode (OHAAE) has been developed and successfully substituted for the current geometrical nosepiece at one end of the movable guard electrode at the National Institute of Metrology, China (NIM). The critical electrical characteristics of the latest OHAAE are investigated by the model tests and eventually implemented with the least mechanical modifications to the new VCCC at NIM. The standard uncertainty of the reproduction of 1 pF capacitance unit from the new VCCC by adopting the latest OHAAE is decreased to $10.5 \times 10^{-9}$ in comparison with that of $20.0 \times 10^{-9}$ by the geometrical nosepiece.

This paper describes an absolute method for calibrating commercial 1000:1 dc current transducers (DCCTs). By adding two auxiliary windings to produce 10:1 and 100:1 ratios, we use a three-step build-up method to establish the 1000:1 current ratio standard. First, we determine the 10:1 ratios of 11 DCCTs through permutation; second, we set up a two-stage composite DCCT to produce a 100:1 ratio; after switching auxiliary windings in the two-stage setup, we then derive the 1000:1 current ratio. The experimental results show that the requirements for the current source and the current meter are not stringent; their Type-B contributions to the overall uncertainties are very small. Type-A uncertainties which include factors such as the experimental environment and possible drifts of the output offsets of the DCCTs are experimentally determined. Repeated tests show that the current ratio standard has an expanded uncertainty of $0.26 \times 10^{-6}$ for the 1000:1 ratio.

In this study, we developed a series of second-order gradient overlap-coupling octagonal superconducting quantum interference device (SQUID) current sensors for transition edge sensor (TES) applications. According to the requirements of TESs, we designed various parameters of SQUID current sensors, including different Josephson junction (JJ) sizes, different hysteresis and screening parameters, input coils with different inductances. The superconducting loop, input coil, and feedback coil of the SQUID current sensors adopt a second-order gradient structure, which can effectively enhance their anti-interference electromagnetic capability. Further, all the coupling structures between the superconducting loop and input/feedback coil adopt overlap-coupling octagonal structures, which can effectively enhance the coefficient of coupling mutual inductance. A series of second-order gradient SQUID current sensors overlap-coupled with input coils of 1.5, 2.5, and 5.5 turns based on Nb/Al–AlO x /Nb JJs were successfully fabricated on 2 inch silicon wafers by optimising the fabrication processes. From the simulation results, a minimal magnetic coupling factor of 0.02 between the feedback coil and input coil is obtained in the overlapped structure of the SQUID current sensor with an input coil of 1.5 turns; thus the magnetic interference between the feedback coil and input coil in this design is negligible. According to the measurement results at liquid–helium temperatures, SQUID current sensors with second-order gradient overlap-coupling octagonal structures have an excellent capability to weaken environmental electromagnetic interference. The SQUID current sensor with an input coil of 5.5 turns has the smallest current sensitivity, 2.4 μA/Φ0 and lowest current noise, 1 pA (√Hz)−1 compared with those of other input coils of different turns. The SQUID current sensor with an input coil of 2.5 turns has the lowest flux noise, 0.3 μΦ0 (√Hz)−1, and the lowest coupled noise energy, 11 h, among all the three different input coils, which are balanced results between the input inductance and the device noise. SQUID current sensors with second-order gradient overlap-coupling octagonal structures show low flux noise, low current noise, and low coupled noise energy, which can be compared with the state-of-art SQUID current sensor worldwide, and can satisfy the requirements of TES applications.

Anxiety and depression are common mental illness in stroke caregivers, resulting in significant stress to the emotion health of caregivers. Caregivers’ emotion can seriously affect the recovery rate of stroke patient, therefore, how to control and affect the caregivers’ anxiety and depression is of great importance. Here three multiple centers observation and validation study were performed to screen out the risk factors for development of anxiety and depression in main family caregiver, and the effect of anxiety and depression of family caregivers on 6-month mortality of patients with moderate-severe stroke. The severity of the stroke, the duration of care time and the medical payment associated with increased risk of anxiety and depression. Anxiety and depression of main family caregivers are associated with increased risk 6-month mortality of patients with moderate-severe stroke. Therefore, the support provided to the family caregivers might have positive effect on prognosis of the patients with stroke.

Background Cerebral ischemia-reperfusion injury (CI/R) is among the most common diseases affecting the central nervous system. Due to the poor efficacy and adverse side effects of the drugs used to treat CI/R in clinical trials, a new treatment strategy is urgently needed. In this study, we aimed to investigate whether miR-103a-3p alleviates CI/R in vivo and vitro and to explore the relevant mechanisms. Methods BV2 microglial cells underwent oxygen-glucose deprivation (OGD) treatment to imitate the pathophysiology of CI/R in vitro. A middle cerebral artery occlusion (MCAO) rat model was established to imitate the pathophysiology of CI/R in vivo. The expression levels of miR-103a-3p and HMGB1 were detected by reverse transcription-polymerase chain reaction (RT-PCR) and western blot. Flow cytometry, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, enzyme-linked immunosorbent assay (ELISA), and hematoxylin and eosin (H&E) and Nissl staining were used to evaluated apoptosis, oxidative stress, inflammatory response, and histopathology, respectively. Results OGD-stimulated BV2 microglial cells and brain tissues with CI/R had low expression of miR-103a-3p but high expression of high mobility group box 1 (HMGB1). As expected, miR-103a-3p and HMGB1 had a targeting relationship. Overexpression of HMGB1 enhanced the the levels of interleukin (IL)-1 beta, tumor necrosis factor-alpha (TNF-α) and malondialdehyde (MDA), but reduced the content of superoxide dismutase (SOD), IL-4, and IL-10, in vitro. Moreover, high expression of HMGB1 aggravated the brain injury of the model rats, and increased the secretion of inflammatory factors, exacerbated oxidative stress, and further induced tissue apoptosis in the brain tissue. Importantly, these effects of HMGB1 overexpression were partly reversed by miR-103a-3p overexpression on HMGB1 interference. Conclusions HMGB1 is targeted by miR-103a-3p, which may be a new strategy in the treatment of CI/R.

Aquaculture ponds are of increasing worldwide concerns as critical sources of atmospheric methane (CH4) and nitrous oxide (N2O), but little is known about these gases emissions as affected by aquaculture species, stocking and water management in aquaculture ponds. Here, a two-year study was carried out to quantify CH4 and N2O emissions from freshwater crab and fish aquaculture ponds in subtropical China. We further explored how the microbial functional genes [CH4: mcrA and pmoA; N2O: archaeal and bacterial amoA (AOA + AOB), nirS, nirK, nosZ] may drive CH4 and N2O release in the crab aquaculture pond typically undergoing flooding-to-drainage alteration. Over the two-year period, annual CH4 and N2O fluxes averaged 0.95 mg m−2 h−1 and 20.94 μg m−2 h−1 in the fish aquaculture, and 0.78 mg m−2 h−1and 28.48 μg m−2 h−1 in the crab aquaculture, respectively. The direct N2O emission factors were estimated to be 0.77% and 0.36% of the total N input by feed or 1.59 g N2O-N kg−1 and 1.06 g N2O-N kg−1 aquaculture yield in the crab and fish ponds, respectively. Among three functional stocking areas, CH4 and N2O emissions were consistently the highest at the feeding area (FA) in the both aquaculture ponds, followed by at the undisturbed area (UA) and aerated area (AA). The shift in sediment soil moisture from waterlogging to drainage conditions significantly increased the abundance of AOB relative to AOA and pmoA, decreased those of denitrifying functional genes (nirS, nirK, nosZ) and mcrA, while did not alter the functional group ratio of nirS + nirK relative to nosZ. Our results highlight that a better understanding of CH4 and N2O emissions from aquaculture ponds requires taking into consideration of data sourced from more diverse aquaculture systems with different management patterns. In addition, a deep analysis of the microbial processes that drive CH4 and N2O production and consumption from aquaculture ponds remains to be addressed in future studies.

As global communities respond to the spread of coronavirus disease 2019 (COVID-19), urban residents worldwide have reduced their mobility, which may have incidentally kept people away from greenspaces. Surprisingly, anecdotal evidence suggests greenspace use surged in Asian cities. In this study, we used the COVID-19 pandemic as a natural experiment to investigate individuals' behavioral changes in greenspace use before and during the pandemic. We created a longitudinal panel dataset comprising Instagram posts from 100,232 users relating to 1185 greenspaces in four Asian cities: Hong Kong, Singapore, Tokyo, and Seoul. We found a 5.3% increase in the odds of people using greenspaces for every 100-case increase in weekly new cases. The models also revealed that people prefer nature parks that are large and close to city centers. In summary, because of the established physical and mental health benefits of greenspaces, people have been escaping to nature to cope with the pandemic in Asian cities., Graphical abstract Unlabelled Image

This paper describes a method for calibrating binary Cryogenic Current Comparator(CCC) winding ratios. The method, described as a step-up technique, involves calibrating the CCC winding first on a 1:1 ratio. By adding an additional 1-turn as a reference, the comparison of two 1-turn windings can be realized, then the two 1-turn windings are added and compared to the 2-turns winding. This process continues until the $2^{n}$ -turns winding is checked. The CCC ratio error and its uncertainty are also analyzed in this paper. Preliminary experiment shows that the ratio $400(2^{8}+2^{7}+2^{4}): 4(2^{2})$ error is below 5 part in 1011.

Different from the noise thermometer in a substitution configuration, a superposition configuration allows a reference signal to be injected into the sense resistor so that the thermal voltage noise and the reference signal can be simultaneously transferred to the measurement electronics through the same transmission line. The construction of a quantum-voltage-calibrated superposition noise thermometer is presented in this paper and preliminary experiments are conducted to demonstrate its feasibility for temperature measurements. A polynomial fitting is used to fit the transfer function of the connection network between the QVNS and the sense resistor.

The experiments were carried out aimed to compare the capacitance measured in terms of the new calculable capacitor standard to the capacitance measured in terms of the von Klitzing constant ( $R_{\mathrm{K}}$ ) using the quantized Hall resistance (QHR). The experiment systems such as the calculable capacitor, the quantized Hall resistance standard, and the impedance measurement chain are briefly presented. The recent two key comparison results on capacitance and resistance standards are also introduced.

Background: We used the first metro system in a developing city as a natural experiment to investigate the causal inference in the new metro’s impact on modal shift and active travel. Material and methods: The treatment group was formed by residents from neighbourhoods located within the 800-m walking distance to new metro stations. The first control group was formed by residents lived 1.6 km away from and outside of walking distance to the nearest station, and the second was 5 km away and outside of cycling distance. The groups were determined by local transit-oriented planning practice and empirical studies on active travel. Of the 5627 participants who had finished a baseline travel behaviour survey before new metro launched, 1770 returned and completed the follow-up survey a year after the metro’s operation, which consists of 833 cohort participants in the treatment group and 937 in the two types of control groups. We used a difference-in-difference method to make before and after comparisons of travel behaviour changes between treatment and control groups. Results: Our longitudinal data analyses revealed diverse travel behaviour changes. In general, people who used to take bus have adopted metro. The average metro usage was 30.9 (28.8–33.3) minutes daily for work trips and 16.6 (14.9–18.7) minutes daily for non-work trips. Walking time decreased 19.7 minutes at most (p

Measuring Variable-frequency big current has a great technical difficulty, you first need transfer Variable-frequency big current to small current is easy to measure, and then transfer variable frequency small current to a voltage. In this paper we uses a zero flux current transformer transfer high current into a small current, after then use a shunt transfer alternating current to a variable frequency voltage, realizing high accuracy variable-frequency big current calibration, measurement uncertainty up to 1×10-4,which can meet the needs of the current calibration,it has been used in many project, and achieved good results.

After the continual investigation on the electrical compensation method for the end effect, the optimal hollow active auxiliary electrode (OHAAE) has been successfully developed and substituted for the current nosepiece in the new vertical calculable capacitor (CC) at NIM. Applying the best compensation voltage of ${U_{\text{best}}}$ obtained from the model tests, the initial measurement result by the OHAAE in the new vertical CC for reproducing the 1 pF capacitance of the same commercial capacitor agrees with that by the nosepiece in the level of ${6.0\times 10^{-9}}$ .

This paper describes the progress on a new measurement of von Klitzing constant $\pmb{(R_{\text{k}})}$ through an experiment linking the new calculable capacitor and the quantized Hall resistance by means of a quadrature transfer at NIM. The recent improvements of the new calculable capacitor, the optical interferometry, the impedance measurement chain are presented.

This paper describes an absolute method for calibrating commercial 1000:1 DC current transducers (DCCTs). By adding two auxiliary windings to produce 10:1 and 100:1 ratios, we use a three-step build-up method to establish the 1000:1 current ratio standard. First, we determine the 10:1 ratios of 11 DCCTs through permutation; second, we set up a two-stage composite DCCT to produce a 100:1 ratio; after switching auxiliary windings in the two-stage setup, we then derive the 1000:1 current ratio. The experimental results will be presented during the conference.