Research and Verification of a Novel Interferometry Method by Joint Processing of Downlink Pseudo-Noise Ranging and DOR Signals for Deep Space Exploration.

The remarkably long distances covered by deep space probes result in extremely weak downlink signals, which poses great challenges for ground measurement systems. In the current climate, improving the comprehensive utilization of downlink signal power to increase the detection distance or enhance the measurement accuracy is of great significance in deep space exploration. Facing this problem, we analyze the delta Differential One-way Range (ΔDOR) error budget of the X-band of the China Deep Space Network (CDSN). Then, we propose a novel interferometry method that detunes one group of DOR beacons and reuses the clock components of regenerative pseudo-code ranging signals for interferometry delay estimation. The primary advantage of this method is its ability to enhance the power utilization efficiency of downlink signals, thereby facilitating more efficient tracking and measurement without necessitating additional design requirements for deep space transponders. Finally, we analyze and verify the correctness and effectiveness of our proposed method using measured data from CDSN. Our results indicate that the proposed method can save approximately 13% of the downlink signal power and increase the detection distance by about 6.25% using typical modulation parameters. Furthermore, if the relative power of other signal components remains unchanged, the power of the DOR tone can be directly increased by more than 100%, improving the deep space exploration ability more significantly.

Oxidative stress-related circulating miRNA-27a is a potential biomarker for diagnosis and prognosis in patients with sepsis.

BACKGROUND: Oxidative stress plays a critical role on the processes of sepsis, and several microRNAs have been identified that may regulate the occurrence of oxidative stress. However, the relation between oxidative stress-related microRNA 27a (miR-27a) and sepsis is unknown. The present study aimed to determine the value of circulating miR-27a for the diagnosis and prognosis of sepsis. METHODS: This retrospective study included 23 patients with sepsis and 25 without sepsis treated at the emergency intensive care unit (EICU) or our institution between January 2019 and January 2020. Levels of circulating miR-27a and levels of oxidative stress-related indicators were measured and compared between sepsis and non-sepsis patients. Receiver operating characteristic (ROC) curve analysis was used to determine diagnostic efficiency of miR-27a. RESULTS: Circulating miR-27a levels in sepsis patients were higher than those in non-sepsis patients (p < 0.05), and levels were significantly higher in patients that died than those that lived (p < 0.05). In patients with sepsis, circulating miR-27a level was positively correlated with serum malondialdehyde (MDA) level (rs = 0.529, p = 0.007), and negatively correlated with serum glutathione peroxidase (GSH-Px) level (rs = - 0.477, p = 0.016). No significant correlation was observed between circulating miR-27a and serum superoxide dismutase (SOD) in sepsis patients (rs = - 0.340, p = 0.096). The area under the ROC curve (AUC) of miR-27a level for prediction of sepsis was 0.717 (p = 0.009) and for 28-day mortality was 0.739 (p = 0.003). CONCLUSIONS: This study showed that circulating miR-27a level is correlated with oxidative stress and mortality in patients with sepsis, and may serve as a potential non-invasive molecular biomarker.

Local Spatial-Temporal Matching Method for Space-Based Infrared Aerial Target Detection.

The feature of a space-based infrared signal is that the intensity of clutter is much stronger than that of an aerial target. Such a feature poses a great challenge to aerial target detection since the existing infrared target detection methods are prone to enhance clutter but ignore the real target, which results in missed detection and false alarms. To tackle the challenge, we propose a concise method based on local spatial-temporal matching (LSM). Specifically, LSM mainly consists of local normalization, local direction matching, spatial-temporal joint model, and inverse matching. Local normalization aims to enhance the target to the same strength as the clutter, so that the weak target will not be ignored. After normalization, a direction-matching step is applied to estimate the moving direction of the background between the basic frame and referenced frame. Then the spatial-temporal joint model is constructed to enhance the target and suppress strong clutter. Similarly, inverse matching is conducted to further enhance the target. Finally, a salience map is obtained, on which the aerial target is extracted by the adaptive threshold segmentation. Experiments conducted on four space-based infrared datasets indicate that LSM handles the above challenge and outperforms seven state-of-the-art methods in space-based infrared aerial target detection.

A High-Accuracy, High Anti-Noise, Unbiased Frequency Estimator Based on Three CZT Coefficients for Deep Space Exploration Mission.

Deep space exploration navigation requires high accuracy of the Doppler measurement, which is equivalent to a frequency estimation problem. Because of the fence effect and spectrum leakage, the frequency estimation performances, which is based on the FFT spectrum methods, are significantly affected by the signal frequency. In this paper, we propose a novel method that utilizes the mathematical relation of the three Chirp-Z Transform (CZT) coefficients around the peak spectral line. The realization, unbiased performance, and algorithm parameter setting rule of the proposed method are described and analyzed in detail. The Monte Carlo simulation results show that the proposed method has a better anti-noise and unbiased performance compared with some traditional estimator methods. Furthermore, the proposed method is utilized to process the raw data of MEX and Tianwen-1 satellites received by Chinese Deep Space Stations (CDSS). The results show that the Doppler estimation accuracy of MEX and Tianwen-1 are both about 3 millihertz (mHz) in 1-s integration, which is consistent with that of ESA/EVN/CDSN and a little better than that of the Chinese VLBI network (CVN). Generally, this proposed method can be effectively utilized to support Chinese future deep space navigation missions and radio science experiments.

Serum level of lipoprotein-associated phospholipase A2 is a potential biomarker of vertebrobasilar dolichoectasia and its progression to cerebral infarction.

BACKGROUND: There are no effective therapies to prevent the occurrence and progression of vertebrobasilar dolichoectasia (VBD). In this study, we investigated the relationship between serum levels of lipoprotein-associated phospholipase A2 (Lp-PLA2) and the occurrence and progression of VBD. METHODS: Sixty (60) cases without VBD and ischemia stroke were considered as Group A, 100 cases with VBD were further divided into Group B (VBD without ischemic stroke, n = 54) and Group C (VBD with first ever acute posterior circulation ischemic stroke, n = 46). Demographic data (such as gender and age) and past medical history (such as hypertension, diabetes, and smoking history) were collected. The levels of serum low-density lipoprotein cholesterol (LDL-C), hypersensitivity C reactive protein (hs-CRP), glycosylated hemoglobin (HbAlc), homocysteine (HCY), uric acid (UA), fibrinogen (Fib), and Lp-PLA2, etc. were measured. Logistic regression analysis was used to assess the related factors of VBD and ischemic stroke secondary to VBD. RESULTS: Logistic multivariate regression analysis showed that only age and the level of serum Lp-PLA2 were significantly higher in group B than those in group A (P < 0.012, P < 0.001, respectively), however, only the level of serum Lp-PLA2 was significantly higher in group C than those in group B (P < 0.001). CONCLUSIONS: The serum marker Lp-PLA2 is an independent risk factor for the occurrence of VBD and the progression of VBD to posterior circulation ischemic stroke. Whether intervening on atherosclerosis could prevent the occurrence and development of VBD needs to be further studied.

Promoting Earth-Based Radar Astronomical Observations of the Moon.

Earth-based radar astronomical observations provide information on surface characteristics, orbits, and rotations for a wide variety of solar system objects. Based on compound radio telescopes, both the Chinese VLBI (Very Long Baseline Interferometry) network (CVN) and the Russian VLBI network (Quasar), in cooperation with the Chinese radar transmitters, we present the current ground radar astronomical observations of the moon. The spectrum of the reflected radio signals was obtained and the Doppler frequency shift in bi-static radar mode was measured. Radar albedo of the observed region and power ratios of the reflected signals with left- and right-hand circular polarizations were determined, allowing us to study the radar reflectivity and near-surface wavelength-scale roughness of the moon. Future developments on radar astronomy are also discussed in the paper.

Berberine Protects Secondary Injury in Mice with Traumatic Brain Injury Through Anti-oxidative and Anti-inflammatory Modulation.

Traumatic brain injury (TBI) is one of the major causes of death and disability worldwide. Novel and effective therapy is needed to prevent the secondary spread of damage beyond the initial injury. The aim of this study was to investigate whether berberine has a neuroprotective effect on secondary injury post-TBI, and to explore its potential mechanism in this protection. The mice were randomly divided into Sham-saline, TBI-saline and TBI-Berberine (50 mg/kg). TBI was induced by Feeney's weight-drop technique. Saline or berberine was administered via oral gavage starting 1 h post-TBI and continuously for 21 days. Motor coordination, spatial learning and memory were assessed using beam-walking test and Morris water maze test, respectively. Brain sections were processed for lesion volume assessment, and expression of neuronal nuclei (NeuN), cyclooxygenase 2 (COX-2), inducible nitric oxide synthase (iNOS), 8-hydroxy-2-deoxyguanosine (8-OHdG), ionized calcium-binding adapter molecule 1 (Iba1) and glial fibrillary acidic protein (GFAP) were detected via immunohistochemistry and immunofluorescence. There were statistically significant improvement in motor coordination, spatial learning and memory in the TBI-Berberine group, compared to the TBI-saline group. Treatment with berberine significantly reduced cortical lesion volume, neuronal loss, COX-2, iNOS and 8-OHdG expression in both the cortical lesion border zone (LBZ) and ipsilateral hippocampal CA1 region (CA1), compared to TBI-saline. Berberine treatment also significantly decreased Iba1- and GFAP-positive cell number in both the cortical LBZ and ipsilateral CA1, relative to saline controls. These results indicated that berberine exerted neuroprotective effects on secondary injury in mice with TBI probably through anti-oxidative and anti-inflammatory properties.

Customized multiwavelets for planetary gearbox fault detection based on vibration sensor signals.

Planetary gearboxes exhibit complicated dynamic responses which are more difficult to detect in vibration signals than fixed-axis gear trains because of the special gear transmission structures. Diverse advanced methods have been developed for this challenging task to reduce or avoid unscheduled breakdown and catastrophic accidents. It is feasible to make fault features distinct by using multiwavelet denoising which depends on the feature separation and the threshold denoising. However, standard and fixed multiwavelets are not suitable for accurate fault feature detections because they are usually independent of the measured signals. To overcome this drawback, a method to construct customized multiwavelets based on the redundant symmetric lifting scheme is proposed in this paper. A novel indicator which combines kurtosis and entropy is applied to select the optimal multiwavelets, because kurtosis is sensitive to sharp impulses and entropy is effective for periodic impulses. The improved neighboring coefficients method is introduced into multiwavelet denoising. The vibration signals of a planetary gearbox from a satellite communication antenna on a measurement ship are captured under various motor speeds. The results show the proposed method could accurately detect the incipient pitting faults on two neighboring teeth in the planetary gearbox.

Homocysteine level at the acute stage of ischemic stroke as a biomarker of poststroke depression: A systematic review and meta-analysis.

Background: Studies on the association of homocysteine level with poststroke depression (PSD) have yielded conflicting results. This systematic review and meta-analysis aimed to evaluate the elevated homocysteine level at the acute stage of ischemic stroke in predicting PSD. Methods: Two authors systematically searched articles indexed in PubMed and Embase databases up to 31 January 2022. Studies evaluating the association of homocysteine level with the development of PSD in patients with acute ischemic stroke were selected. Results: A total of 10 studies involving 2,907 patients were identified. The pooled adjusted odds ratio (OR) of PSD was 3.72 [95% confidence intervals (CI) 2.03-6.81] for the top vs. bottom homocysteine level. The value of elevated homocysteine level in predicting PSD was stronger in ≥6-month follow-up (OR 4.81; 95% CI 3.12-7.43) than those in ≤ 3-month follow-up subgroup (OR 3.20; 95% CI 1.29-7.91). Moreover, a per unit increase in homocysteine level conferred a 7% higher risk of PSD. Conclusion: Elevated homocysteine level in the acute stage of ischemic stroke may be an independent predictor of PSD.

The Diagnostic Value of Mitochondrial Mass of Peripheral T Lymphocytes in Early Sepsis.

Background: Studies have shown that lymphocyte dysfunction can occur during the early stages of sepsis and that cell dysfunction is associated with mitochondrial dysfunction. Therefore, quantifying the mitochondrial function of lymphocytes in patients with sepsis could be valuable for the early diagnosis of sepsis. Methods: Seventy-nine patients hospitalized from September 2020 to September 2021 with Sepsis-3 were retrospectively analyzed and subsequently compared with those without sepsis. Results: Univariate analysis showed statistical differences between the data of the two groups regarding age, neutrophil/lymphocyte, procalcitonin (PCT), C-reactive protein, total bilirubin, serum creatinine, type B natriuretic peptide, albumin, prothrombin time, activated partial thromboplastin time, lactic acid, single-cell mitochondrial mass (SCMM)-CD3, SCMM-CD4, SCMM-CD8, and Acute Physiology and Chronic Health Evaluation II score (P < 0.05). Multivariate logistic regression analysis performed on the indicators mentioned above demonstrated a statistical difference in PCT, lactic acid, SCMM-CD4, and SCMM-CD8 levels between the two groups (P < 0.05). The receiver operating characteristic curves of five models were subsequently compared [area under the curve: 0.740 (PCT) vs. 0.933 (SCMM-CD4) vs. 0.881 (SCMM-CD8) vs. 0.961 (PCT + SCMM-CD4) vs. 0.915 (PCT+SCMM-CD8), P < 0.001]. Conclusion: SCMM-CD4 was shown to be a better diagnostic biomarker of early sepsis when compared with the traditional biomarker, PCT. Furthermore, the value of the combination of PCT and SCMM-CD4 in the diagnosis of early sepsis was better than that of SCMM-CD4 alone.

Severe periodontitis is associated with the serum levels of hypersensitive C reactive protein and lipoprotein-associated phospholipase A2 in the patients of acute ischemic stroke.

BACKGROUND: Periodontitis is associated with the pathogenesis of atherosclerotic plaque, and hypersensitive C reactive protein (hs-CRP) and lipoprotein-associated phospholipase A2 (Lp-PLA2) are the serum biomarkers of the stability of atherosclerotic plaque. Whether periodontitis is associated with the serum level of hs-CRP and Lp-PLA2 of acute ischemic stroke remains unclear. MATERIAL AND METHODS: We recruited 103 cases with acute ischemic stroke within 7 days after stroke onset. Pocket depth and clinical attachment loss were assessed by oral examination to define the severe periodontitis. Demographic information including gender, age and body weight index, income level, education level, past medical history include smoking history, drinking history, ischemic stroke history, coronary heart disease, hypertension, diabetes and hyperlipidemia were collected, and serum biomarkers including white blood cell (WBC), fibrinogen, total cholesterol (TC), triglyceride (TG), lower density lipoprotein (LDL-C), high density lipoprotein (HDL-C), hs-CRP, HemoglobinA1c (HbAlc), Homocysteine (HCY) and Lp-PLA2 were tested. RESULTS: 65 (63.1%) cases were diagnosed as severe periodontitis. Severe periodontitis group showed more male, age, drinking history, higher levels of hs-CRP and Lp-PLA2. Multivariate logistic regression showed that severe periodontitis was were significantly associated with hs-CRP (OR = 2.367, 95%CI: 1.182-4.738; P = .015) and Lp-PLA2 (OR = 2.577, 95% CI: 1.010-6.574; P = .048). CONCLUSIONS: Severe periodontitis is independently associated with the serum Level of hs-CRP and Lp-PLA2 in patients with acute ischemic stroke. Whether the improvement of periodontitis could decrease the occurrence and re-occurrence of ischemic stroke by stablizating atherosclerotic plaque need be further studied in future.