RM-GPT: Enhance the comprehensive generative ability of molecular GPT model via LocalRNN and RealFormer.

Due to the surging of cost, artificial intelligence-assisted de novo drug design has supplanted conventional methods and become an emerging option for drug discovery. Although there have arisen many successful examples of applying generative models to the molecular field, these methods struggle to deal with conditional generation that meet chemists' practical requirements which ask for a controllable process to generate new molecules or optimize basic molecules with appointed conditions. To address this problem, a Recurrent Molecular-Generative Pretrained Transformer model is proposed, supplemented by LocalRNN and Residual Attention Layer Transformer, referred to as RM-GPT. RM-GPT rebuilds GPT model's architecture by incorporating LocalRNN and Residual Attention Layer Transformer so that it is able to extract local information and build connectivity between attention blocks. The incorporation of Transformer in these two modules enables leveraging the parallel computing advantages of multi-head attention mechanisms while extracting local structural information effectively. Through exploring and learning in a large chemical space, RM-GPT absorbs the ability to generate drug-like molecules with conditions in demand, such as desired properties and scaffolds, precisely and stably. RM-GPT achieved better results than SOTA methods on conditional generation.

The mediating effect of stigma between self-perceived burden and loneliness in stroke patients.

Introduction: Stroke patients may experience reduced socialization and feelings of isolation due to post-stroke sequelae such as impaired motor function and cognitive deficits. Factors associated with loneliness need to be explored to develop targeted interventions. However, little is known about the impact of self-perceived burden and illness stigma on loneliness in this population.The aim of this study was to explore the mediating effect of stigma on self-perceived burden and loneliness in stroke patients. Methods: The cluster random sampling method was adopted to select 1028 stroke patients from the neurology department of third-grade A hospitals and second-grade A hospitals in 5 cities of Henan Province from May 2022 to August 2022. A general data questionnaire, self-perceived burden scale, stroke stigma scale, and loneliness scale were used to investigate. The structural equation model was used to analyze the mediating effect of stigma between self-perceived burden and stigma. Results: The loneliness of stroke patients was positively correlated with self-perceived burden and stigma. The results of the mediation analysis showed that stigma played a complete mediating role between self-perceived burden and loneliness. Discussion: The results of the study revealed the relationship between self-perceived burden, stigma, and loneliness in stroke patients. Stigma mediated the relationship between self-perceived burden and loneliness in this population.Stigma should be emphasized as an important modifiable psychological factor that affects loneliness of stroke patients.

Effects of pump laser intensity on the cell temperature working point in a K-Rb-21Ne spin-exchange relaxation-free co-magnetometer.

The cell temperature working point optimization of the spin-exchange relaxation-free (SERF) co-magnetometer is studied theoretically and experimentally in this article. Based on the steady-state solution of the Bloch equations, the steady-state response model of the K-Rb-21Ne SERF co-magnetometer output signal with cell temperature is established in this paper. And combined with the model, a method to find the optimal working point of the cell temperature that incorporates the pump laser intensity is proposed. The scale factor of the co-magnetometer under different pump laser intensities and cell temperatures is obtained experimentally, and the long-term stability of the co-magnetometer at the different cell temperatures with corresponding pump laser intensities is measured. The results show that the bias instability of the co-magnetometer is reduced from 0.0311 deg/h to 0.0169 deg/h by obtaining the optimal working point of the cell temperature, which verifies the validity and accuracy of the theoretical derivation and the proposed method.

Comprehensive analysis of the effects of magnetic field gradient on the performance of the SERF co-magnetometer.

The magnetic field gradient affects the improvement of sensitivity and magnetic field suppression ability of the spin-exchange relaxation-free co-magnetometer. This paper proposes a response model of a co-magnetometer considering magnetic field gradient based on state-space method. The effects of transverse and longitudinal magnetic field gradients on the system's scale factor, bandwidth and magnetic field response are analyzed. The analysis shows that transverse gradient affects the whole frequency band of system response, including steady-state and dynamic performance, while longitudinal gradient only affects steady-state response. With the increase of the gradient, the effect becomes more significant. The test results are in agreement with the theory, proving the accuracy of the theoretical analysis. The rotational sensitivity at 1 Hz decreases from 6.51 ×10-6 °/s/Hz1/2 to 5.05×10-5 °/s/Hz1/2 in the presence of a magnetic field gradient of -40 nT/cm, so the effect of the magnetic field gradient is critical. This work provides an accurate model for evaluating the effects of magnetic field gradients and provides a method for suppressing gradients using gradient coils, which are important for improving the sensitivity and accuracy of co-magnetometers.

Atomic spin precession detection method based on the Mach-Zehnder interferometer in an atomic comagnetometer.

A new method for the detection of atomic spin precession based on the Mach-Zehnder interferometer (MZI) is proposed and experimentally demonstrated. Different from the conventional polarization detection methods which obtain the atomic spin precession signal by measuring the change of the probe laser power, the proposed method uses the laser modulated by an electro-optic phase modulator (EOM) as the source of the interferometer, and obtains the atomic spin precession signal by measuring the phase difference between the two arms of the MZI. The output of interferometer is independent of the probe laser power, which avoids the system error caused by the fluctuation of the probe laser power, and the long-term stability of the system is effectively improved. At the same time, the method adopts high-frequency electro-optic modulation, which can effectively suppress low-frequency noise, such as 1/f noise, and can significantly improve the detection sensitivity. The rotation sensitivity and long-term stability of the atomic comagnetometer were tested using the MZI detection method and a typical detection method, respectively. The comparison results show that the proposed method has the highest low frequency sensitivity and the potential to improve the long-term stability of the system.

Study on the Magnetic Noise Characteristics of Amorphous and Nanocrystalline Inner Magnetic Shield Layers of SERF Co-Magnetometer.

With the widespread use of magneto-sensitive elements, magnetic shields are an important part of electronic equipment, ultra-sensitive atomic sensors, and in basic physics experiments. Particularly in Spin-exchange relaxation-free (SERF) co-magnetometers, the magnetic shield is an important component for maintaining the SERF state. However, the inherent noise of magnetic shield materials is an important factor limiting the measurement sensitivity and accuracy of SERF co-magnetometers. In this paper, both amorphous and nanocrystalline materials were designed and applied as the innermost magnetic shield of an SERF co-magnetometer. Magnetic noise characteristics of different amorphous and nanocrystalline materials used as the internal magnetic shielding layer of the magnetic shielding system were analyzed. In addition, the effects on magnetic noise due to adding aluminum to amorphous and nanocrystalline materials were studied. The experimental results show that compared with an amorphous material, a nanocrystalline material as the inner magnetic shield layer can effectively reduce the magnetic noise and improve the sensitivity and precision of the rotation measurement. Nanocrystalline material is very promising for inner shield composition in SERF co-magnetometers. Furthermore, its ultra-thin structure and low cost have significant application value in the miniaturization of SERF co-magnetometers.

Analysis on the effect of electron spin polarization on a hybrid optically pumped K-Rb-21Ne co-magnetometer.

In this paper, the effect of longitudinal electron spin polarization under the combined action of alkali metal density ratio and pump laser power density on the hybrid optically pumped co-magnetometer operated in the spin-exchange relaxation-free (SERF) regime is studied. The AC response model of rotation velocity and magnetic noise of the SERF co-magnetometer system is proposed, and the factors of frequency and system bandwidth are considered. Based on the proposed response model, the error equation of the system is obtained, and the relationship between alkali metal density ratio and pump laser power density and the system noise response is theoretically analyzed and experimentally tested. The results show that when the product of pumping rate and alkali metal density ratio is greater than the electron spin relaxation rate, there is a longitudinal electron spin polarization point that minimizes the system error. In addition, the range of minimum error calculated results obtained by changing the pumping rate for the cells with different alkali metal density ratios is within 5% of the average value, that is, their minimum error potential is roughly the same within a certain range. Under the experimental conditions in this paper, due to the limitation of the electron spin relaxation rate and the operating capacity of the pump laser, the optimal alkali metal density ratio range is about 1/100-1/300.

Environmental Risk Assessment of Polycyclic Aromatic Hydrocarbons in Farmland Soils near Highways: A Case Study of Guangzhou, China.

Recently, the rapid growth in vehicle activity in rapidly urbanized areas has led to the discharge of large amounts of polycyclic aromatic hydrocarbons (PAHs) into roadside soils and these compounds have gradually accumulated in the soil, which poses a serious threat to national food security and public health. However, previous studies did not clearly investigate the seasonal differences in PAH pollution of roadside soil by different highways. Therefore, based on field investigations, this study collected 84 soil surface samples to compare the pollution characteristics of 16 PAHs in farmland soils located near different roads in different seasons in Guangzhou, China. The results showed that the concentration of Σ16PAHs in farmland soils in spring (with a mean value of 258.604 µg/kg) was much higher than that in autumn (with a mean value of 157.531 µg/kg). There are differences in the PAH compositions in spring (4 ring > 3 ring > 5 ring > 6 ring) and autumn (4 ring > 5 ring > 6 ring > 3 ring). The proportion of 4−6 ring PAHs was much higher than 2−3 ring PAHs in both seasons. The spatial differences were significant. The sampling areas with higher concentrations of 16 PAHs were Tanbu Town, Huadu District (TB), Shitan Town, Zengcheng District (ST), and Huashan Town, Huadu District (HS), while the lowest concentration was in Lanhe Town, Nansha District (LH). The results of the diagnostic ratios showed that the main source of soil PAHs consists of a mixed source from petroleum and biomass combustion. The results from the total pollution assessment method and Nemerow index method indicated that the pollution levels of PAHs in the farmland soils indicated weak contamination. Our study provides a scientific basis for the prevention and control of soil pollution in farmlands near highways.

Transverse light-shift in a spin-exchange relaxation-free co-magnetometer: measurement, decoupling, and suppression.

The transverse light-shift can induce non-negligible polarization error in the output signal of spin-exchange relaxation-free (SERF) co-magnetometer. In this paper, a novel method for rapid measurement of transverse light-shift based on the error of steady-state response of co-magnetometer is proposed firstly, then the sources of transverse light-shift in a compact SERF co-magnetometer is modeled and analyzed from three aspects: the non-ideal linear polarization of probe laser, the circular dichroism of the atomic spin ensembles, and the stress-induced birefringence effect of the cell wall. Furthermore, the decoupling and suppression methods of transverse light-shift based on a degree of circular polarization (DOCP) regulation scheme is presented, to realize the decoupling measurement of the transverse light-shift introduced by the whole co-magnetometer cell, and cancel it out with the non-ideal linear polarization of the probe laser. Eventually, the DOCP regulation scheme suggested in this paper achieves more than a 67% suppression ratio in transverse light-shift, and the short- and long-term performance of SERF co-magnetometer are improved due to the reduction of the coupling effect between the probe laser power and transverse field. Moreover, the measurement, decoupling and suppression methods provided in this paper also have the potential to be applied to other atomic sensors, such as the SERF magnetometers and nuclear spin co-magnetometers.

Using Multisource Data to Assess PM2.5 Exposure and Spatial Analysis of Lung Cancer in Guangzhou, China.

Elevated air pollution, along with rapid urbanization, have imposed higher health risks and a higher disease burden on urban residents. To accurately assess the increasing exposure risk and the spatial association between PM2.5 and lung cancer incidence, this study integrated PM2.5 data from the National Air Quality Monitoring Platform and location-based service (LBS) data to introduce an improved PM2.5 exposure model for high-precision spatial assessment of Guangzhou, China. In this context, the spatial autocorrelation method was used to evaluate the spatial correlation between lung cancer incidence and PM2.5. The results showed that people in densely populated areas suffered from higher exposure risk, and the spatial distribution of population exposure risk was highly consistent with the dynamic distribution of the population. In addition, areas with PM2.5 roughly overlapped with areas with high lung cancer incidence, and the lung cancer incidence in different locations was not randomly distributed, confirming that lung cancer incidence was significantly associated with PM2.5 exposure. Therefore, dynamic population distribution has a great impact on the accurate assessment of environmental exposure and health burden, and it is necessary to use LBS data to improve the exposure assessment model. More mitigation controls are needed in highly populated and highly polluted areas.

Analysis and suppression of the misalignment error for the pumping laser in the atomic comagnetometer.

The misalignment error of the pumping laser in the atomic comagnetometer (ACM) dramatically diminishes the efficiency of the optical pumping process (characterized by the polarization of the hybrid atomic spin ensembles containing electron spins and nuclear spins) and deteriorates the performance of the ACM (characterized by the Allan standard deviation). In this work, a steady-state response model considering the misalignment error of the pumping laser is established and an in-situ evaluation method for this error is proposed. Based on the evaluation method, the influence of this misalignment error on the pumping efficiency and the performance of the ACM is quantitatively analyzed. Furthermore, a pumping laser alignment method based on the second harmonic of a single-beam magnetometer is then proposed, whose effectiveness is verified by experiments. The experimental results show that compared to the original ACM with the severely misaligned pumping laser, the polarization of the hybrid atomic spin ensembles of the ACM with the pumping laser aligned by the proposed method is increased by about 19%, and the corresponding Allan variance at 100s is reduced by about 40%.

Analysis and suppression of the polarization error for the optical rotation detection system in an atomic comagnetometer.

This paper investigates the laser polarization error in the optical rotation detection system (ORDS) of an atomic comagnetometer (ACM), which will seriously degrade the long-term performance of the ORDS. We first establish an optical transmission model of the ORDS by using Jones matrix concerning the optical imperfection of polarizers. Then, we analyze the polarization error based on this model and propose a novel error suppression method. Finally, we experimentally test the long-term performance of the ORDS and the ACM before and after the polarization error suppression to verify the effectiveness of the proposed method. The experimental results show that the long-term performance of the ORDS and the ACM can be improved by approximately 3.4 times with the proposed polarization error suppression method.

Nuclear magnetic field measurement of the spin-exchange optically pumped noble gas in a self-compensated atomic comagnetometer.

We demonstrate a new method to determine the nuclear magnetic field of the spin-exchange optically pumped noble gas in a self-compensated atomic comagnetometer based on the steady-state AC response. The result shows that it has higher resolution and precision than a previous method based on the transient process. Furthermore, a convergence frequency is observed in the low-frequency region and its parameter dependence is studied simulatively, which may inspire further research into its relationship with the strong suppression mechanism of the self-compensation ability for the low-frequency magnetic field. We also prove that this method can be developed for suppression of residual main magnetic field to improve the systematic stability of the comagnetometer.

Miniaturized optical rotation detection system based on liquid crystal variable retarder in a K-Rb-21Ne gyroscope.

A novel method to control the light intensity stability and modulate the probe light polarization using a liquid crystal variable retarder (LCVR) to detect atomic spin precession simultaneously in a K-Rb-21Ne gyroscope is reported. A sinusoidal driving voltage is applied to drive the LCVR and is skillfully used to produce a high-frequency modulation for the probe light. The modulation helps to avoid electronic detection noise appearing at low frequencies and allows for phase-sensitive detection. The coefficient of rate ramp can be reduced from 1.31 (deg/h)/h to 0.05 (deg/h)/h (Allan deviation), and the bias instability of about 0.08 deg/h at the averaging time of 200 s is achieved. Therefore, the long-term stability of the angular velocity measurement can be improved and other optical modulators can be replaced to facilitate the miniaturization of the gyroscope by using this intensity modulation detection method. This optical rotation detection method also can be applied to other miniaturized atomic sensors, such as atomic magnetometers.

Precision measurements of optically thick alkali metal number density within a hybrid alkali metal cell.

The number density of alkali metal vapors and their ratio within hybrid cells is of great significance for the optimal rotation sensitivity of alkali metal-noble gas comagnetometers. To measure the number density of optically thick Rb vapor accurately within a hybrid cell containing optically thin K vapor and optically thick Rb vapor, a novel method combining alkali metal absorption spectroscopy and Raoult's law is proposed in this paper. The relative error between experimental results and results calculated by empirical formula is within ±5% from 365 to 450 K, and the measurement accuracy is improved more than 10 times compared to previous study. This novel method could be applied to check the number density ratio of alkali metal within hybrid cells more precisely.

Monitoring monthly surface water dynamics of Dongting Lake using Sentinel-1 data at 10 m.

High temporal resolution water distribution maps are essential for surface water monitoring because surface water exhibits significant inner-annual variation. Therefore, high-frequency remote sensing data are needed for surface water mapping. Dongting Lake, the second-largest freshwater lake in China, is famous for the seasonal fluctuations of its inundation extents in the middle reaches of the Yangtze River. It is also greatly affected by the Three Gorges Project. In this study, we used Sentinel-1 data to generate surface water maps of Dongting Lake at 10 m resolution. First, we generated the Sentinel-1 time series backscattering coefficient for VH and VV polarizations at 10 m resolution by using a monthly composition method. Second, we generated the thresholds for mapping surface water at 10 m resolution with monthly frequencies using Sentinel-1 data. Then, we derived the monthly surface water distribution product of Dongting Lake in 2016, and finally, we analyzed the inner-annual surface water dynamics. The results showed that: (1) The thresholds were -21.56 and -15.82 dB for the backscattering coefficients for VH and VV, respectively, and the overall accuracy and Kappa coefficients were above 95.50% and 0.90, respectively, for the VH backscattering coefficient, and above 94.50% and 0.88, respectively, for the VV backscattering coefficient. The VV backscattering coefficient achieved lower accuracy due to the effect of the wind causing roughness on the surface of the water. (2) The maximum and minimum areas of surface water were 2040.33 km2 in July, and 738.89 km2 in December. The surface water area of Dongting Lake varied most significantly in April and August. The permanent water acreage in 2016 was 556.35 km2, accounting for 19.65% of the total area of Dongting Lake, and the acreage of seasonal water was 1525.21 km2. This study proposed a method to automatically generate monthly surface water at 10 m resolution, which may contribute to monitoring surface water in a timely manner.

Rotation sensing decoupling of a dual-axis K-Rb-21Ne atomic comagnetometer.

A dual-axis atomic comagnetometer can sense the angular rotation of two measurement axes simultaneously and independently. However, there is a cross-talk coupling effect between the two axes because of the residual magnetic field and the light shift arising from the pumping laser. Here, we propose a scheme to eliminate the rotation coupling of dual-axis K-Rb-N21e atomic comagnetometers. The residual magnetic field can be effectively removed by controlling the comagnetometer at the magnetic compensation point and the magnetic shielding layer. The light shift could be eliminated by using the K atom light shift to counteract the Rb atom light shift, in which the light shift of K atoms was optimized to the decoupling point by finely adjusting the pumping laser wavelength of the K D1 line. The feasibility and efficiency of this decoupling scheme have been experimentally verified. The output response of the coupling axis is reduced by two orders of magnitude compared to the sensitive axis. This scheme can also be applied to any atomic comagnetometer with hybrid optical pumping that experiences cross-talk coupling.

Common-mode noise reduction in an atomic spin gyroscope using optical differential detection.

Optical rotation of linearly polarized light is used to measure atom spin precession in an atomic spin gyroscope (ASG). However, the common-mode noise in the polarization measurement seriously affects the performance of the sensitive ASG. Here we propose an optical differential detection method based on the photoelastic polarization modulation, which could effectively eliminate the light power fluctuation of the laser source and optical elements, while removing the polarization noise and the residual birefringence. The feasibility and efficiency of this method have been verified experimentally. The rotation sensitivity of the ASG is an order of magnitude better, and the long-time stability is significantly improved. In addition, this method is easier to implement because noise sources do not need to be strictly distinguished.

Correlations of IFN-γ-inducible protein-10 with the risk of chronic hepatitis B and the efficacy of interferon therapy in Asians.

PURPOSE: The aim of this study was to identify the correlations of IFN-γ-inducible protein-10 (IP-10) with the risk of chronic hepatitis B (CHB) and the efficacy of interferon therapy in Asians. METHOD: Serum IP-10 levels were assayed using enzyme linked immunosorbent assay (ELISA) in both CHB and control group. CHB group received interferon-α2b treatment to compare the pre-treatment and post-treatment serum IP-10 levels. Relevant studies met predefined inclusion and exclusion criteria were enrolled into further meta-analysis. Stata 12.0 software was applied for data analysis. RESULT: Our case-control study demonstrated that CHB group had evaluated serum IP-10 levels compared with control group (285.7 ± 41.6 pg/mL vs. 79.1 ± 33.8 pg/mL, t = 21.85, P < 0.001. After treatment for 12 weeks, CHB group had remarkably decreased post-treatment serum IP-10 levels than pre-treatment (78.5 ± 20.4 pg/mL vs. 285.7 ± 41.6 pg/mL, t = 33.76, P < 0.001). No significance was observed on post-treatment serum IP-10 levels between CHB and control group (78.5 ± 20.4 pg/mL vs. 78.1 ± 33.8 pg/mL, t = 0.07, P = 0.947). Meta-analysis results demonstrated that serum IP-10 levels in CHB group were obviously higher than healthy controls (SMD = 2.21, 95% CI = 1.55~2.87, P < 0.001). A subgroup based on the HBeAg states revealed that serum IP-10 levels in both HBeAg-positive and HBeAg-negative CHB patients were notably higher than healthy controls (HBeAg-positive: SMD = 2.00, 95% CI = 1.13-2.87, P < 0.001; HBeAg-negative: SMD = 1.34, 95% CI = 0.97-1.72, P < 0.001). CONCLUSION: Serum IP-10 may be correlated with the risk of CHB and the efficiency of interferon therapy, thus IP-10 may be a good biomarker for the diagnosis and treatment of CHB.