Tropospheric delay acts as a systematic error source in the Global Navigation Satellite Systems(GNSS) positioning. Empirical models UNB3, UNB3 m, UNB4 and EGNOS have been developed for use in Satellite-Based Augmentat...Tropospheric delay acts as a systematic error source in the Global Navigation Satellite Systems(GNSS) positioning. Empirical models UNB3, UNB3 m, UNB4 and EGNOS have been developed for use in Satellite-Based Augmentation Systems(SBAS). Model performance, however, is limited due to the low spatial resolution of the look-up tables for meteorological parameters. A new design has been established in this study for improving performance of the tropospheric delay model by more effectively eliminating the error produced by tropospheric delay. The spatiotemporal characteristics of the Zenith Tropospheric Delay(ZTD) were analyzed with findings that ZTD exhibits different annual variations at different locations and decreases exponentially with height increasing. Spherical harmonics are utilized based on the findings to fit the annual mean and amplitude of the ZTD on a global scale and the exponential function is utilized for height corrections, yielding the ZTrop model. On a global scale, the ZTrop features an average deviation of ?1.0 cm and Root Mean Square(RMS) of 4.7 cm compared with the International GNSS Service(IGS) ZTD products, an average deviation of 0.0 cm and RMS of 4.5 cm compared with the Global Geodetic Observing System(GGOS) ZTD data, and an average deviation of ?1.3 cm and RMS of 5.2 cm compared with the ZTD data from the Constellation Observing System of Meteorology, Ionosphere, and Climate(COSMIC). The RMS of the ZTrop model is 14.5% smaller than that of UNB3, 6.0% smaller than that of UNB3 m, 16% smaller than that of UNB4, 14.5% smaller than that of EGNOS and equivalent to the sophisticated GPT2+Saas model in comparison with the IGS ZTD products. The ZTrop, UNB3 m and GPT2+Saas models are finally evaluated in GPS-based Precise Point Positioning(PPP), as the models act to aid in obtaining PPP position error less than 1.5 cm in north and east components and relative large error(>5 cm) in up component with respect to the random walk approach.展开更多
OBJECTIVE:To screen for m RNAs associated with blood stasis syndrome and to explore the genetic mechanisms of blood stasis syndrome in hypertension.METHODS:This study involved groups of patients with hypertension and ...OBJECTIVE:To screen for m RNAs associated with blood stasis syndrome and to explore the genetic mechanisms of blood stasis syndrome in hypertension.METHODS:This study involved groups of patients with hypertension and blood stasis,including those with Qi deficiency,Qi stagnation,cold retention and heat retention;as well as hypertensive patients without blood stasis and healthy individuals.Human umbilical vein endothelial cells were co-cultured with the sera of these healthy individuals and patients with blood stasis syndrome.Total RNA was extracted from these cells and assessed by a high-throughput sequencing method(Solexa)and digital gene expression.Differentially expressed genes among these six groups were compared using whole genome sequences,and m RNAs associated with blood stasis syndrome identified.Differences in gene use and gene ontology function were an-alyzed.Genes enriched significantly and their pathways were determined,as were network interactions,and encoded proteins.Gene identities were confirmed by real-time polymerase chain reactions.RESULTS:Compared with cells cultured in sera of the blood stasis groups,those culture in sera of healthy individuals and of the non-blood stasis group showed 11 and 301 differences,respectively in stasis-related genes.Genes identified as differing between the blood stasis and healthy groups included activating transcription factor 4,activating transcription factor 3,DNA-damage inducible transcription factor 3,Tribbles homolog 3,CCAAT/enhancer binding protein-β,and Jun proto-oncogene(JUN).Pathway and protein interaction network analyses showed that these genes were associated with endoplasmic reticulum stress.Cells cultured in sera of patients with blood stasis and Qi deficiency,Qi stagnation,heat retention,and cold retention were compared with cells cultured in sera of patients with the other types blood stasis syndrome.The comparison showed differences in expression of 28,28,34,and 32 specific genes,respectively.CONCLUSION:The pathogenesis of blood stasis syndrome in hypertension is related to endoplasmic reticulum stress and involves the differential expression of the activating transcription factor 4,activating transcription factor 3,DNA-damage inducible transcription factor 3,Tribbles homolog 3,CCAAT/enhancer binding protein-β,and JUN genes.展开更多
基金the National Natural Science Foundation of China (Grant Nos. 41174012 & 41274022)the National High Technology Research and Development Program of China (Grant No. 2013AA122502)+1 种基金the Fundamental Research Funds for the Central Universities (Grant No. 2014214020202)the Surveying and Mapping Basic Research Program of National Administration of Surveying, Mapping and Geoinformation (Grant No. 13-02-09)
文摘Tropospheric delay acts as a systematic error source in the Global Navigation Satellite Systems(GNSS) positioning. Empirical models UNB3, UNB3 m, UNB4 and EGNOS have been developed for use in Satellite-Based Augmentation Systems(SBAS). Model performance, however, is limited due to the low spatial resolution of the look-up tables for meteorological parameters. A new design has been established in this study for improving performance of the tropospheric delay model by more effectively eliminating the error produced by tropospheric delay. The spatiotemporal characteristics of the Zenith Tropospheric Delay(ZTD) were analyzed with findings that ZTD exhibits different annual variations at different locations and decreases exponentially with height increasing. Spherical harmonics are utilized based on the findings to fit the annual mean and amplitude of the ZTD on a global scale and the exponential function is utilized for height corrections, yielding the ZTrop model. On a global scale, the ZTrop features an average deviation of ?1.0 cm and Root Mean Square(RMS) of 4.7 cm compared with the International GNSS Service(IGS) ZTD products, an average deviation of 0.0 cm and RMS of 4.5 cm compared with the Global Geodetic Observing System(GGOS) ZTD data, and an average deviation of ?1.3 cm and RMS of 5.2 cm compared with the ZTD data from the Constellation Observing System of Meteorology, Ionosphere, and Climate(COSMIC). The RMS of the ZTrop model is 14.5% smaller than that of UNB3, 6.0% smaller than that of UNB3 m, 16% smaller than that of UNB4, 14.5% smaller than that of EGNOS and equivalent to the sophisticated GPT2+Saas model in comparison with the IGS ZTD products. The ZTrop, UNB3 m and GPT2+Saas models are finally evaluated in GPS-based Precise Point Positioning(PPP), as the models act to aid in obtaining PPP position error less than 1.5 cm in north and east components and relative large error(>5 cm) in up component with respect to the random walk approach.
基金Supported by National Scientific Fund(Assessing Micro RNA-mediated Endothelial Cell Injury in Blood Stasis,No.81173157)Guangdong Scientific Fund(Assessing Micro RNA-mediated Endothelial Cell Injury in Blood Stasis,No.10151063201000045)
文摘OBJECTIVE:To screen for m RNAs associated with blood stasis syndrome and to explore the genetic mechanisms of blood stasis syndrome in hypertension.METHODS:This study involved groups of patients with hypertension and blood stasis,including those with Qi deficiency,Qi stagnation,cold retention and heat retention;as well as hypertensive patients without blood stasis and healthy individuals.Human umbilical vein endothelial cells were co-cultured with the sera of these healthy individuals and patients with blood stasis syndrome.Total RNA was extracted from these cells and assessed by a high-throughput sequencing method(Solexa)and digital gene expression.Differentially expressed genes among these six groups were compared using whole genome sequences,and m RNAs associated with blood stasis syndrome identified.Differences in gene use and gene ontology function were an-alyzed.Genes enriched significantly and their pathways were determined,as were network interactions,and encoded proteins.Gene identities were confirmed by real-time polymerase chain reactions.RESULTS:Compared with cells cultured in sera of the blood stasis groups,those culture in sera of healthy individuals and of the non-blood stasis group showed 11 and 301 differences,respectively in stasis-related genes.Genes identified as differing between the blood stasis and healthy groups included activating transcription factor 4,activating transcription factor 3,DNA-damage inducible transcription factor 3,Tribbles homolog 3,CCAAT/enhancer binding protein-β,and Jun proto-oncogene(JUN).Pathway and protein interaction network analyses showed that these genes were associated with endoplasmic reticulum stress.Cells cultured in sera of patients with blood stasis and Qi deficiency,Qi stagnation,heat retention,and cold retention were compared with cells cultured in sera of patients with the other types blood stasis syndrome.The comparison showed differences in expression of 28,28,34,and 32 specific genes,respectively.CONCLUSION:The pathogenesis of blood stasis syndrome in hypertension is related to endoplasmic reticulum stress and involves the differential expression of the activating transcription factor 4,activating transcription factor 3,DNA-damage inducible transcription factor 3,Tribbles homolog 3,CCAAT/enhancer binding protein-β,and JUN genes.
