This work is to retrieve emission-line spectra from the“Unknown”data set in LAMOST DR7 V1.2,most of which are low signal-to-noise ratios spectra.In the work,we perform emission line search and redshift calculations ...This work is to retrieve emission-line spectra from the“Unknown”data set in LAMOST DR7 V1.2,most of which are low signal-to-noise ratios spectra.In the work,we perform emission line search and redshift calculations on the Unknown data set to get possible emission line galaxy spectra.Taking the galaxy spectra released by LAMOST as templates,the Product Quantization(PQ)based approximate nearest neighbor(ANN)search is used to retrieve the nearest neighbors of each spectrum.We keep the spectra for which the calculated redshift and the published redshift of the template meet the threshold,and 16,188 spectra with emission lines are obtained from the LAMOST DR7 Unknown data set.After visual inspection of spectra 10,266 spectra are left,in which 5828 spectra are identified as emission-line galaxies,1782 spectra show ionization nebula features,and other 2656 are not clearly classified.Among 5828 spectra,5720 can be found in Strasbourg astronomical Data Center catalog,Sloan Digital Sky Survey catalog,or NASA/IPAC Extragalactic Database catalog.The 108 spectra(corresponding to 106unique coordinates of R.A.and decl.)which have no record in these three databases are new discoveries;for the1782 spectra showing ionization nebula features,most of them have radial velocities less than 150 kilometers per second.We check them with the latest version of WISE HⅡcatalog V2.0(short for HIICat V2)and 985 out of the1782 spectra belong to 72 HⅡregions.Of these HⅡregions,43 were previously identified while the other 29 are newly identified in this work including 797 newly observed spectra.Besides,there are still 2656 spectra that cannot be clearly classified although they have obvious emission lines and with small redshift.Finally,106 new emissionline galaxies and 29 new Galactic HⅡregions are identified,and we conclude that the ANN method sped up by the PQ algorithm is efficient in solving the problem of pairing spectra with massive data set to figure out their classes.We present our result at the link http://paperdata.china-vo.org/LY_paper/Work2/press Work2_last.zip.展开更多
We present a large-scale simultaneous survey of the CO isotopologues(^(12)CO,^(13)CO,and C^(18)O)J=1-0 line emission toward the Galactic plane region of l=106°.65 to 109°.50 and b=-1°.85 to 0°.95 u...We present a large-scale simultaneous survey of the CO isotopologues(^(12)CO,^(13)CO,and C^(18)O)J=1-0 line emission toward the Galactic plane region of l=106°.65 to 109°.50 and b=-1°.85 to 0°.95 using the Purple Mountain Observatory 13.7 m millimeter-wavelength telescope.Except for the molecular gas in the solar neighborhood,the emission from the molecular gas in this region is concentrated in the velocity range of[-60,-35]km s^(-1).The gas in the region can be divided into four clouds,with mass in the range of~10^(3)-10^(4)M☉.We have identified 25 filaments based on the^(13)CO data.The median excitation temperature,length,line mass,line width,and virial parameter of the filaments are 10.89 K,8.49 pc,146.11 M☉pc^(-1),1.01 km s^(-1),and 3.14,respectively.Among these filaments,eight have virial parameters of less than 2,suggesting that they are gravitationally bound and can lead to star formation.Nineteen HⅡregions or candidates have previously been found in the region and we investigate the relationships between these HⅡregions/candidates and surrounding molecular clouds in detail.Using morphology similarity and radial velocity consistency between HⅡregions/candidates and molecular clouds as evidence for association,and raised temperature and velocity broadening as signatures of interaction,we propose that 12 HⅡregions/candidates are associated with their surrounding molecular clouds.In the case of the HⅡregion of S142,the energy of the HⅡregion is sufficient to maintain the turbulence in the surrounding molecular gas.展开更多
Cerebral autoregulation(CA)is the mechanism that maintains stable cerebral blood flow(CBF)despite fluctuations in systemic blood pressure,crucial for brain homeostasis.Recent evidence highlights distinct regional vari...Cerebral autoregulation(CA)is the mechanism that maintains stable cerebral blood flow(CBF)despite fluctuations in systemic blood pressure,crucial for brain homeostasis.Recent evidence highlights distinct regional variations in CA between the anterior(carotid)and posterior(vertebrobasilar)circulations.Noninvasive neuromonitoring techniques,such as transcranial Doppler,transfer function analysis,and near-infrared spectroscopy,facilitate the dynamic assessment of CBF and autoregulation.Studies indicate a robust autoregulatory capacity in the anterior circulation,characterized by rapid adjustments in vascular resistance.On the contrary,the posterior circulation,mainly supplied by the vertebral arteries,may have a lower autoregulatory capacity.in acute brain injuries such as intracerebral and subarachnoid hemorrhage,and traumatic brain injuries,dynamic CA can be significantly altered in the posterior circulation.Proposed physiological mechanisms of impaired CA in the posterior circulation include:(1)Decreased sympathetic innervation of the vasculature impairing compensatory vasoreactivity;(2)Endothelial dysfunction;(3)Increased cerebral metabolic rate of oxygen consumption within the visual cortex causing CBFmetabolism(i.e.,neurovascular)uncoupling;and(4)Impaired blood-brain barrier integrity leading to impaired astrocytic mediated release of vasoactive substances(e.g.nitric oxide,potassium,and calcium ions).Furthermore,more research is needed on the effects of collateral circulation,as well as the circle of Willis variants,such as the fetal-type posterior cerebral artery,on dynamic CA.Improving our understanding of these mechanisms is crucial to improving the diagnosis,prognosis,and management of various cerebrovascular disorders.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)under Nos.U1931209,11903008,U1931106the Science Foundation of De Zhou University(grant No.2019xjrc39)+1 种基金Guo Shou Jing Telescope(the Large Sky Area Multi-Object Fiber Spectroscopic Telescope,LAMOST)is a National Major Scientific Project built by the Chinese Academy of Sciencesprovided by the National Development and Reform Commission。
文摘This work is to retrieve emission-line spectra from the“Unknown”data set in LAMOST DR7 V1.2,most of which are low signal-to-noise ratios spectra.In the work,we perform emission line search and redshift calculations on the Unknown data set to get possible emission line galaxy spectra.Taking the galaxy spectra released by LAMOST as templates,the Product Quantization(PQ)based approximate nearest neighbor(ANN)search is used to retrieve the nearest neighbors of each spectrum.We keep the spectra for which the calculated redshift and the published redshift of the template meet the threshold,and 16,188 spectra with emission lines are obtained from the LAMOST DR7 Unknown data set.After visual inspection of spectra 10,266 spectra are left,in which 5828 spectra are identified as emission-line galaxies,1782 spectra show ionization nebula features,and other 2656 are not clearly classified.Among 5828 spectra,5720 can be found in Strasbourg astronomical Data Center catalog,Sloan Digital Sky Survey catalog,or NASA/IPAC Extragalactic Database catalog.The 108 spectra(corresponding to 106unique coordinates of R.A.and decl.)which have no record in these three databases are new discoveries;for the1782 spectra showing ionization nebula features,most of them have radial velocities less than 150 kilometers per second.We check them with the latest version of WISE HⅡcatalog V2.0(short for HIICat V2)and 985 out of the1782 spectra belong to 72 HⅡregions.Of these HⅡregions,43 were previously identified while the other 29 are newly identified in this work including 797 newly observed spectra.Besides,there are still 2656 spectra that cannot be clearly classified although they have obvious emission lines and with small redshift.Finally,106 new emissionline galaxies and 29 new Galactic HⅡregions are identified,and we conclude that the ANN method sped up by the PQ algorithm is efficient in solving the problem of pairing spectra with massive data set to figure out their classes.We present our result at the link http://paperdata.china-vo.org/LY_paper/Work2/press Work2_last.zip.
基金sponsored by the National Key R&D Program of China with grant 2017YFA0402701the CAS Key Research Program of Frontier Sciences with grant QYZDJSSW-SLH047+4 种基金the support of NSFC grants 11973091,12073079,and 12103025the supports by China Postdoctoral Science Foundation No.2021M691532Jiangsu Postdoctoral Research Funding Program No.2021K179B makes use of data products from the Wide-field Infrared Survey Explorer,which is a joint project of the University of California,Los Angelesthe Jet Propulsion Laboratory/California Institute of Technology,funded by the National Aeronautics and Space Administrationmakes use of data products from the Virginia Tech Spectral-Line Survey(VTSS),which is supported by the National Science Foundation。
文摘We present a large-scale simultaneous survey of the CO isotopologues(^(12)CO,^(13)CO,and C^(18)O)J=1-0 line emission toward the Galactic plane region of l=106°.65 to 109°.50 and b=-1°.85 to 0°.95 using the Purple Mountain Observatory 13.7 m millimeter-wavelength telescope.Except for the molecular gas in the solar neighborhood,the emission from the molecular gas in this region is concentrated in the velocity range of[-60,-35]km s^(-1).The gas in the region can be divided into four clouds,with mass in the range of~10^(3)-10^(4)M☉.We have identified 25 filaments based on the^(13)CO data.The median excitation temperature,length,line mass,line width,and virial parameter of the filaments are 10.89 K,8.49 pc,146.11 M☉pc^(-1),1.01 km s^(-1),and 3.14,respectively.Among these filaments,eight have virial parameters of less than 2,suggesting that they are gravitationally bound and can lead to star formation.Nineteen HⅡregions or candidates have previously been found in the region and we investigate the relationships between these HⅡregions/candidates and surrounding molecular clouds in detail.Using morphology similarity and radial velocity consistency between HⅡregions/candidates and molecular clouds as evidence for association,and raised temperature and velocity broadening as signatures of interaction,we propose that 12 HⅡregions/candidates are associated with their surrounding molecular clouds.In the case of the HⅡregion of S142,the energy of the HⅡregion is sufficient to maintain the turbulence in the surrounding molecular gas.
文摘Cerebral autoregulation(CA)is the mechanism that maintains stable cerebral blood flow(CBF)despite fluctuations in systemic blood pressure,crucial for brain homeostasis.Recent evidence highlights distinct regional variations in CA between the anterior(carotid)and posterior(vertebrobasilar)circulations.Noninvasive neuromonitoring techniques,such as transcranial Doppler,transfer function analysis,and near-infrared spectroscopy,facilitate the dynamic assessment of CBF and autoregulation.Studies indicate a robust autoregulatory capacity in the anterior circulation,characterized by rapid adjustments in vascular resistance.On the contrary,the posterior circulation,mainly supplied by the vertebral arteries,may have a lower autoregulatory capacity.in acute brain injuries such as intracerebral and subarachnoid hemorrhage,and traumatic brain injuries,dynamic CA can be significantly altered in the posterior circulation.Proposed physiological mechanisms of impaired CA in the posterior circulation include:(1)Decreased sympathetic innervation of the vasculature impairing compensatory vasoreactivity;(2)Endothelial dysfunction;(3)Increased cerebral metabolic rate of oxygen consumption within the visual cortex causing CBFmetabolism(i.e.,neurovascular)uncoupling;and(4)Impaired blood-brain barrier integrity leading to impaired astrocytic mediated release of vasoactive substances(e.g.nitric oxide,potassium,and calcium ions).Furthermore,more research is needed on the effects of collateral circulation,as well as the circle of Willis variants,such as the fetal-type posterior cerebral artery,on dynamic CA.Improving our understanding of these mechanisms is crucial to improving the diagnosis,prognosis,and management of various cerebrovascular disorders.
