36 research outputs found
Quality assessment of YUNYAO radio occultation data in the neutral atmosphere
Get PDFGlobal Navigation Satellite System (GNSS) radio occultation (RO) data are an important component of numerical weather prediction (NWP) systems. To incorporate more GNSS-RO data into NWP systems, commercial RO data have become an excellent option. Tianjin Yunyao Aerospace Technology Co., Ltd. (YUNYAO) plans to launch a meteorological constellation of 90 satellites equipped with GNSS-RO instruments, which will significantly increase the amount of GNSS-RO data in NWP systems. This study evaluates the quality of neutral atmospheric refractivity and bending angle profiles from YUNYAO satellites Y003 to Y010 during the period from 1 May to 31 July 2023. Compared with the refractivity and bending angle calculated from ERA5, the absolute values of the mean bias (MB) for YUNYAO refractivity and bending angle data are less than 1.54 % and 4.51 %, respectively, in the height range of 0 to 40 km and close to 0 between 4 and 40 km. The standard deviations (SDs) are below 3.35 % and 11.06 %, respectively, with variations in SDs among different GNSS satellites, especially in the lower troposphere and the stratosphere. Second, the refractivity error SD of YUNYAO RO data is estimated using the “three-cornered hat” (3CH) method and multiple data sets. In the pressure range of 1000–10 hPa, the refractivity error SD of YUNYAO RO data is below 2.53 %, and the differences in refractivity error SDs among different GNSS satellites do not exceed 0.52 %. Finally, compared to COSMIC-2 and Metop-C RO data, YUNYAO RO data exhibit consistent refractivity error SDs and are smaller within 300–50 hPa.</p
Supplementary_Material_a_clean_copy - Influence of More Than 5 Years of Continuous Exposure to Antipsychotics on Cerebral Functional Connectivity of Chronic Schizophrenia
No full textSupplementary_Material_a_clean_copy for Influence of More Than 5 Years of Continuous Exposure to Antipsychotics on Cerebral Functional Connectivity of Chronic Schizophrenia by Qi Miao, Chengcheng Pu, Zhijiang Wang, Chao-Gan Yan, Chuan Shi, Qingjiu Cao, Xijin Wang, Zhang Cheng, Xue Han, Lei Yang, Yunyao Lai, Yanbo Yuan, Hong Ma, Keqing Li, Nan Hong and Xin Yu in The Canadian Journal of Psychiatry</p
The Yunyao LEO Satellite Constellation: Occultation Results of the Neutral Atmosphere Using Multi-System Global Navigation Satellites
No full textThe Yunyao Aerospace Constellation Program is the core project being developed by Yunyao Aerospace Technology Co., Ltd., Tianjin, China. It aims to provide scientific data for weather forecasting, as well as research on the ionosphere and neutral atmosphere. It is expected to launch 90 high time resolution weather satellites. Currently, the Yunyao space constellation provides nearly 16,000 BDS, GPS, GLONASS, and Galileo multi-system occultation profile products on a daily basis. This study initially calculates the precise orbits of Yunyao LEO satellites independently using each GNSS constellation, allowing the derivation of the neutral atmospheric refractive index profile. The precision of the orbit product was evaluated by comparing carrier-phase residuals (ranging from 1.48 cm to 1.68 cm) and overlapping orbits. Specifically, for GPS-based POD, the average 3D overlap accuracy was 4.93 cm, while for BDS-based POD, the average 3D overlap accuracy was 5.18 cm. Simultaneously, the global distribution, the local time distribution, and penetration depth of the constellation were statistically analyzed. BDS demonstrates superior performance with 21,093 daily occultation profiles, significantly exceeding GPS and GLONASS by 15.9% and 121%, respectively. Its detection capability is evidenced by 79.75% of profiles penetrating below a 2 km altitude, outperforming both GPS (78.79%) and GLONASS (71.75%) during the 7-day analysis period (DOY 169–175, 2023). The refractive index profile product was also compared with the ECWMF ERA5 product. At 35 km, the standard deviation of atmospheric refractivity for BDS remains below 1%, while for GPS and GLONASS it is found at around 1.5%. BDS also outperforms GPS and GLONASS in terms of the standard deviation in the atmospheric refractive index. These results indicate that Yunyao satellites can provide high-quality occultation product services, like for weather forecasting. With the successful establishment of the global BDS-3 network, the space signal accuracy has been significantly enhanced, with BDS-3 achieving a Signal-in-Space Ranging Error (SISRE) of 0.4 m, outperforming GPS (0.6 m) and GLONASS (1.7 m). This enables superior full-link occultation products for BDS
Abnormalities of cingulate cortex in antipsychotic-naive chronic schizophrenia
No full textWhile several morphometric studies have postulated a critical contribution of the cingulate cortex (CC) to the pathophysiology of schizophrenia based on abnormalities in CC volume, other studies have been inconclusive. Most such studies have focused only on changes in cortical volume, whereas other morphometric parameters such as surface area and cortical thickness could be more relevant and possibly account for these discrepancies. Furthermore, factors such as antipsychotic drug use and treatment duration may also influence cortical morphology. To clarify the association between schizophrenia and CC deficits, we investigated morphometric abnormalities of the CC in antipsychotic drug (AD)-naive chronic schizophrenia patients by comparing T1-weighted magnetic resonance images (T1WI-MRI) from patients (n=17) to healthy controls (n=17) using the surface-based morphometry program FreeSurfer. Partial correlations were examined between abnormal morphometric measures and both clinical variables and cognitive performance scores. Compared to healthy controls, drug-naive schizophrenia patients exhibited significantly lower volumes in both left rostral anterior CC (rACC) and left posterior CC (PCC). These reductions in CC volume resulted from reduced surface area rather than reduced cortical thickness. There was also a significant relationship between left PCC volume and working memory in patients. No significant correlations were observed between CC volume and clinical variables. The results suggest that abnormalities in the CC as manifested by reduced surface area may contribute to cognitive dysfunction in schizophrenia. This article is part of a Special Issue entitled SI: PSC and the brain. (C) 2015 Elsevier B.V. All rights reserved.National Scientific and Technical Support Programs of China [2007BAI17B04]; Peking University People's Hospital Research and Development Fund [RDC2012-04]SCI(E)[email protected]; [email protected],SI105-113163
Data_Sheet_1_Reappraisal of Non-vitamin K Antagonist Oral Anticoagulants in Atrial Fibrillation Patients: A Systematic Review and Meta-Analysis.PDF
No full textBackground: Recent observational studies have compared effectiveness and safety profiles between non-vitamin K antagonist oral anticoagulants (NOACs) and warfarin in patients with atrial fibrillation (AF). Nevertheless, the confounders may exist due to the nature of clinical practice-based data, thus potentially influencing the reliability of results. This systematic review and meta-analysis were conducted to compare the effect of NOACs with warfarin based on the propensity score-based observational studies vs. randomized clinical trials (RCTs).Methods: Articles included were systematically searched from the PubMed and EMBASE databases until March 2021 to obtain relevant studies. The primary outcomes were stroke or systemic embolism (SSE) and major bleeding. Hazard ratios (HRs) and 95% confidence intervals (CIs) of the outcomes were extracted and then pooled by the random-effects model.Results: A total of 20 propensity score-based observational studies and 4 RCTs were included. Compared with warfarin, dabigatran (HR, 0.82 [95% CI, 0.71–0.96]), rivaroxaban (HR, 0.80 [95% CI, 0.75–0.85]), apixaban (HR, 0.75 [95% CI, 0.65–0.86]), and edoxaban (HR, 0.71 [95% CI, 0.60–0.83]) were associated with a reduced risk of stroke or systemic embolism, whereas dabigatran (HR, 0.76 [95% CI, 0.65–0.87]), apixaban (HR, 0.61 [95% CI, 0.56–0.67]), and edoxaban (HR, 0.58 [95% CI, 0.45–0.74]) but not rivaroxaban (HR, 0.92 [95% CI, 0.84–1.00]) were significantly associated with a decreased risk of major bleeding based on the observational studies. Furthermore, the risk of major bleeding with dabigatran 150 mg was significantly lower in observational studies than that in the RE-LY trial, whereas the pooled results of observational studies were similar to the data from the corresponding RCTs in other comparisons.Conclusion: Data from propensity score-based observational studies and NOAC trials consistently suggest that the use of four individual NOACs is non-inferior to warfarin for stroke prevention in AF patients.</p
Pathformer: Multi-scale Transformers with Adaptive Pathways for Time Series Forecasting
Get PDFTransformers for time series forecasting mainly model time series from limited or fixed scales, making it challenging to capture different characteristics spanning various scales. We propose Pathformer, a multi-scale Transformer with adaptive pathways. It integrates both temporal resolution and temporal distance for multi-scale modeling. Multi-scale division divides the time series into different temporal resolutions using patches of various sizes. Based on the division of each scale, dual attention is performed over these patches to capture global correlations and local details as temporal dependencies. We further enrich the multi-scale Transformer with adaptive pathways, which adaptively adjust the multi-scale modeling process based on the varying temporal dynamics of the input, improving the accuracy and generalization of Pathformer. Extensive experiments on eleven real-world datasets demonstrate that Pathformer not only achieves state-of-the-art performance by surpassing all current models but also exhibits stronger generalization abilities under various transfer scenarios. The code is made available at https://github.com/decisionintelligence/pathformer.Accepted by the 12th International Conference on Learning Representations (ICLR 2024
