We present the observational results from a detailed timing analysis of the black hole candidate EXO 1846-031 during its outburst in 2019 with the observations of Insight-HXMT,NICER and MAXI.This outburst can be class...We present the observational results from a detailed timing analysis of the black hole candidate EXO 1846-031 during its outburst in 2019 with the observations of Insight-HXMT,NICER and MAXI.This outburst can be classified roughly into four different states.Type-C quasi-periodic oscillations(QPOs)observed by NICER(about 0.1-6 Hz)and Insight-HXMT(about 0.7-8 Hz)are also reported in this work.Meanwhile,we study various physical quantities related to QPO frequency.The QPO rms-frequency relationship in the energy band 1-10 keV indicates that there is a turning pointing in frequency around2 Hz,which is similar to that of GRS 1915+105.A possible hypothesis for the relationship above may be related to the inclination of the source,which may require a high inclination to explain it.The relationships between QPO frequency and QPO rms,hardness,total fractional rms and count rate have also been found in other transient sources,which can indicate that the origin of type-C QPOs is non-thermal.展开更多
Gut microbiota community shift with coronary artery disease(CAD)has been reported in several limited cohorts during the past several years.However,whether the enriched or decreased microbiota taxa with CAD can be repr...Gut microbiota community shift with coronary artery disease(CAD)has been reported in several limited cohorts during the past several years.However,whether the enriched or decreased microbiota taxa with CAD can be reproducible deserves further investigation and validation.In this study,78 human subjects were recruited.Of these,19 were diagnosed without stenosis in coronary artery(control group,referred to herein as Ctrl),14 with stenosis less than 50%(LT50),and 45 with stenosis greater than 50%(GT50).Fecal samples were collected and DNA was extracted to perform 16S ribosomal RNA(rRNA)gene sequencing.The operational taxonomic units(OTUs)were analyzed to identify taxa specific to different groups;next,multivariate logistic regression was employed to test whether the defined taxa could independently predict CAD risk.We found that Deltaproteobacteria,Fusobacterium,Bilophila,Actinomyces,and Clostridium XIX were enriched in Ctrl;Prevotellaceae,Parabacteriodes,and Butyricicoccus were enriched in LT50;and Roseburia and Butyricimonas were enriched in GT50.Further analysis revealed that increased populations of Deltaproteobacteria,Fusobacterium,Bilophila,and Desulfovibrionaceae were associated with a 0.26-fold,0.21-fold,0.18-fold,and 0.26-fold decreased risk of CAD,respectively(p<0.05),and an increased Prevotellaceae population was associated with a 5.63-fold increased risk of CAD(p<0.01).A combination of the 20 microbial taxa achieved an area under the receiver operating characteristic(ROC)curve of higher than 0.88 for all discriminations between LT50 vs Ctrl,GT50 vs Ctrl,LT50+GT50 vs Ctrl,and GT50 vs Ctrl+LT50.However,the microbial taxa previously reported as enriched in CAD patients or healthy controls could not be observed in our cohort except for Bacteroides.In conclusion,CAD patients showed a different microbial taxa signature than the healthy controls.However,the non-reproducibility of the microbiota taxa enriched in CAD across different cohorts limits the use of this signature in early diagnosis and prevention.Only decreased Bacteroides abundance was found to be a reliable marker to indicate CAD progression.展开更多
The LE is the low energy telescope that is carried on Insight-HXMT.It uses swept charge devices(SCDs)to detect soft X-ray photons.LE’s time response is caused by the structure of the SCDs.With theoretical analysis an...The LE is the low energy telescope that is carried on Insight-HXMT.It uses swept charge devices(SCDs)to detect soft X-ray photons.LE’s time response is caused by the structure of the SCDs.With theoretical analysis and Monte Carlo simulations we discuss the influence of LE time response(LTR)on the timing analysis from three aspects:the power spectral density,the pulse profile and the time lag.After the LTR,the value of power spectral density monotonously decreases with the increasing frequency.The power spectral density of a sinusoidal signal reduces by a half at frequency 536 Hz.The corresponding frequency for quasi-periodic oscillation(QPO)signals is 458 Hz.The root mean square(RMS)of QPOs holds a similar behaviour.After the LTR,the centroid frequency and full width at half maxima(FWHM)of QPOs signals do not change.The LTR reduces the RMS of pulse profiles and shifts the pulse phase.In the time domain,the LTR only reduces the peak value of the cross-correlation function while it does not change the peak position;thus it will not affect the result of the time lag.When considering the time lag obtained from two instruments and one among them is LE,a 1.18 ms lag is expected caused by the LTR.The time lag calculated in the frequency domain is the same as that in the time domain.展开更多
基金the HXMT mission,a project funded by China National Space Administration(CNSA)and the Chinese Academy of Sciences(CAS)supported by the National Key R&D Program of China(2016YFA0400800)the National Natural Science Foundation of China(Grant Nos.11673023,U1838201,U1838115,U1838111,U1838202,11733009 and U1838108)。
文摘We present the observational results from a detailed timing analysis of the black hole candidate EXO 1846-031 during its outburst in 2019 with the observations of Insight-HXMT,NICER and MAXI.This outburst can be classified roughly into four different states.Type-C quasi-periodic oscillations(QPOs)observed by NICER(about 0.1-6 Hz)and Insight-HXMT(about 0.7-8 Hz)are also reported in this work.Meanwhile,we study various physical quantities related to QPO frequency.The QPO rms-frequency relationship in the energy band 1-10 keV indicates that there is a turning pointing in frequency around2 Hz,which is similar to that of GRS 1915+105.A possible hypothesis for the relationship above may be related to the inclination of the source,which may require a high inclination to explain it.The relationships between QPO frequency and QPO rms,hardness,total fractional rms and count rate have also been found in other transient sources,which can indicate that the origin of type-C QPOs is non-thermal.
基金This study was supported in part by the Shanghai Xuhui District Science and Technology Commission,Artificial Intelligence Project 2 for Jia-Lu HuShanghai Public Health Talents Training Project(GWV-10.2-YQ11)for Jia-Lu Hu+1 种基金the National Natural Science Foundation of China(81873538)for Yan Yanthe National Heart,Lung,and Blood Institute and the Office of the Director,National Institutes of Health(RO1HL130819)for Zeneng Wang.
文摘Gut microbiota community shift with coronary artery disease(CAD)has been reported in several limited cohorts during the past several years.However,whether the enriched or decreased microbiota taxa with CAD can be reproducible deserves further investigation and validation.In this study,78 human subjects were recruited.Of these,19 were diagnosed without stenosis in coronary artery(control group,referred to herein as Ctrl),14 with stenosis less than 50%(LT50),and 45 with stenosis greater than 50%(GT50).Fecal samples were collected and DNA was extracted to perform 16S ribosomal RNA(rRNA)gene sequencing.The operational taxonomic units(OTUs)were analyzed to identify taxa specific to different groups;next,multivariate logistic regression was employed to test whether the defined taxa could independently predict CAD risk.We found that Deltaproteobacteria,Fusobacterium,Bilophila,Actinomyces,and Clostridium XIX were enriched in Ctrl;Prevotellaceae,Parabacteriodes,and Butyricicoccus were enriched in LT50;and Roseburia and Butyricimonas were enriched in GT50.Further analysis revealed that increased populations of Deltaproteobacteria,Fusobacterium,Bilophila,and Desulfovibrionaceae were associated with a 0.26-fold,0.21-fold,0.18-fold,and 0.26-fold decreased risk of CAD,respectively(p<0.05),and an increased Prevotellaceae population was associated with a 5.63-fold increased risk of CAD(p<0.01).A combination of the 20 microbial taxa achieved an area under the receiver operating characteristic(ROC)curve of higher than 0.88 for all discriminations between LT50 vs Ctrl,GT50 vs Ctrl,LT50+GT50 vs Ctrl,and GT50 vs Ctrl+LT50.However,the microbial taxa previously reported as enriched in CAD patients or healthy controls could not be observed in our cohort except for Bacteroides.In conclusion,CAD patients showed a different microbial taxa signature than the healthy controls.However,the non-reproducibility of the microbiota taxa enriched in CAD across different cohorts limits the use of this signature in early diagnosis and prevention.Only decreased Bacteroides abundance was found to be a reliable marker to indicate CAD progression.
基金the National Key R&D Program of China(2016YFA0400800)the National Natural Science Foundation of China(Grant Nos.U1838201,U1838202,U1838101 and U1938109)the Insight-HXMT mission,a project funded by China National Space Administration(CNSA)and the Chinese Academy of Sciences(CAS)。
文摘The LE is the low energy telescope that is carried on Insight-HXMT.It uses swept charge devices(SCDs)to detect soft X-ray photons.LE’s time response is caused by the structure of the SCDs.With theoretical analysis and Monte Carlo simulations we discuss the influence of LE time response(LTR)on the timing analysis from three aspects:the power spectral density,the pulse profile and the time lag.After the LTR,the value of power spectral density monotonously decreases with the increasing frequency.The power spectral density of a sinusoidal signal reduces by a half at frequency 536 Hz.The corresponding frequency for quasi-periodic oscillation(QPO)signals is 458 Hz.The root mean square(RMS)of QPOs holds a similar behaviour.After the LTR,the centroid frequency and full width at half maxima(FWHM)of QPOs signals do not change.The LTR reduces the RMS of pulse profiles and shifts the pulse phase.In the time domain,the LTR only reduces the peak value of the cross-correlation function while it does not change the peak position;thus it will not affect the result of the time lag.When considering the time lag obtained from two instruments and one among them is LE,a 1.18 ms lag is expected caused by the LTR.The time lag calculated in the frequency domain is the same as that in the time domain.
