The High Altitude Detection of Astronomical Radiation(HADAR)experiment,which was constructed in Tibet,China,combines the wide-angle advantages of traditional EAS array detectors with the high-sensitivity advantages of...The High Altitude Detection of Astronomical Radiation(HADAR)experiment,which was constructed in Tibet,China,combines the wide-angle advantages of traditional EAS array detectors with the high-sensitivity advantages of focused Cherenkov detectors.Its objective is to observe transient sources such as gamma-ray bursts and the counterparts of gravitational waves.This study aims to utilize the latest AI technology to enhance the sensitivity of HADAR experiments.Training datasets and models with distinctive creativity were constructed by incorporating the relevant physical theories for various applications.These models can determine the type,energy,and direction of the incident particles after careful design.We obtained a background identification accuracy of 98.6%,a relative energy reconstruction error of 10.0%,and an angular resolution of 0.22°in a test dataset at 10 TeV.These findings demonstrate the significant potential for enhancing the precision and dependability of detector data analysis in astrophysical research.By using deep learning techniques,the HADAR experiment’s observational sensitivity to the Crab Nebula has surpassed that of MAGIC and H.E.S.S.at energies below 0.5 TeV and remains competitive with conventional narrow-field Cherenkov telescopes at higher energies.In addition,our experiment offers a new approach for dealing with strongly connected,scattered data.展开更多
Six rumen-cannulated lactating Guanzhong goats were used to investigate changes in ruminal fermentation pattern and the microbiota following a subacute rtmainal acidosis （SARA） inducing procedure. Induction of SARA ...Six rumen-cannulated lactating Guanzhong goats were used to investigate changes in ruminal fermentation pattern and the microbiota following a subacute rtmainal acidosis （SARA） inducing procedure. Induction of SARA was performed by increasing dietary non-fiber carbohydrate （NFC） to neutral detergent fiber （NDF） ratio from 1.02 （stage 1） to 1.24 （stage 2）, 1.63 （stage 3） and 2.58 （stage 4）. A dynamic pH monitoring system, real-time fluorescent quantitative PCR and conventional anaerobic culture were used to assess changes in ruminal pH and microbiota. Results indicated that rumen fermentation patterns changed significantly with increased NFC：NDF ratio. The decline in ruminal pH was caused by increased ruminal total volatile fatty acids （TVFA）, which was mainly attributed to a significant increase in ruminal butyrate, rather than the accumulation of ruminal lactic acid. In addition, in the course of SARA, the number of rumen microoganisms altered significantly, with increases in ruminal amylolytic bacteria, Lactobacilli, Streptococcus bovis and Megasphaera elsdenii, the latter particularly dramatically indicating that it may be the main factor responsible for the increase in butyrate, and decrease in protozoa.展开更多
Ground-based arrays of imaging atmospheric Cherenkov telescopes(IACTs)are the most sensitiveγ-ray detectors for energies of approximately 100 Ge V and above.One such IACT is the High Altitude Detection of Astronomica...Ground-based arrays of imaging atmospheric Cherenkov telescopes(IACTs)are the most sensitiveγ-ray detectors for energies of approximately 100 Ge V and above.One such IACT is the High Altitude Detection of Astronomical Radiation(HADAR)experiment,which uses a large aperture refractive water lens system to capture atmospheric Cherenkov photons(i.e.,the imaging atmospheric Cherenkov technique).The telescope array has a low threshold energy and large field of view,and can continuously scan the area of the sky being observed,which is conducive to monitoring and promptly responding to transient phenomena.The process ofγ-hadron separation is essential in very-high-energy(>30 Ge V)γ-ray astronomy and is a key factor for the successful utilization of IACTs.In this study,Monte Carlo simulations were carried out to model the response of cosmic rays within the HADAR detectors.By analyzing the Hillas parameters and the distance between the event core and the telescope,the distinction between air showers initiated byγ-rays and those initiated by cosmic rays was determined.Additionally,a Quality Factor was introduced to assess the telescope’s ability to suppress the background and to provide a more effective characterization of its performance.展开更多
The generation of polycyclic aromatic hydrocarbons （PAHs） during coking was studied and the contents of sixteen PAHs were measured by the devices of ultrasonic abstraction and high performance liquid chromatography ...The generation of polycyclic aromatic hydrocarbons （PAHs） during coking was studied and the contents of sixteen PAHs were measured by the devices of ultrasonic abstraction and high performance liquid chromatography for single coal coking and blended coal coking. The results indicated that the amount of generated PAHs during the first 1--4 h of coking is the most. Among these PAHs, the tetranuclear PAHs have a major portion and the Benzo[a]pyrene which can cause cancer, and teratogenesis and mutation is generated for a larger concentration more than emission standard value. Two PAHs are the main pollutants of PAHs pollution.展开更多
The observation of short gamma ray bursts(SGRBs)in the TeV energy range plays an important role in understanding the radiation mechanism and probing potential new physics,such as Lorentz invariance violation(LIV).Howe...The observation of short gamma ray bursts(SGRBs)in the TeV energy range plays an important role in understanding the radiation mechanism and probing potential new physics,such as Lorentz invariance violation(LIV).However,no SGRBs have been observed in this energy range owing to the short duration of SGRBs and the weakness of current experiments.New experiments with new technology are required to detect the very high energy(VHE)emission of SGRBs.In this study,we simulate the VHE γ-ray emissions from SGRBs and calculate the annu-al detection rate with the High Altitude Detection of Astronomical Radiation(HADAR)experiment.First,a set of pseudo-SGRB samples is generated and checked using the observations of the Fermi-GBM,Fermi-LAT,and Swift-BAT measurements.The annual detection rate is calculated from these SGRB samples based on the performance of the HADAR instrument.As a result,the HADAR experiment can detect 0.5 SGRBs per year if the spectral break-off of γ-rays caused by the internal absorption and Klein-Nishina(KN)effect is larger than 100 GeV.For a GRB090510-like GRB in HADAR's view,it should be possible to detect approximately 2000 photons considering the internal absorption and KN effect.With a time delay assumption due to LIV effects,a simulated light curve of GRB090510 has evident energy dependence.We hope that the HADAR experiment can perform SGRB observa-tions and test our calculations in the future.展开更多
A lot of iron-bearing slags were produced,and whose grade is much more than that of industrial iron ore grade.Chemical analysis and phase identification shows that the iron-bearing slag is amorphous,has fayalite main ...A lot of iron-bearing slags were produced,and whose grade is much more than that of industrial iron ore grade.Chemical analysis and phase identification shows that the iron-bearing slag is amorphous,has fayalite main phase,iron grade is 36.10%,and is difficult to recover iron from the slag.Thermodynamic calculation indicates that CO cannot reduce fayalite at high temperature and carbon direct reduction can be effective.Moreover,the reaction begins at 770 ℃ and the temperature can be reduced down to 500℃ when CaO is added.On this basis,a method is put forward to making direct enrichment of iron by taking carbon contained pellets to realize the rapid reduction of fayalite,and the direct reduction process were studied in this paper.Experiments show that xC/xO should be less than 1.5 for the need of reduction and carburization,and CaO and Al2O3 can spur the reduction of fayalite.On conditions that xC/xO is 1.2,metallization rate can be 77% when temperature is 1 250 ℃ and only carbon is added,and metallization rate can be 74% when temperature is 1 200 ℃ and only CaO is added.Moreover the addition of Al2O3 can get a higher metallization rate（10% or so） than usual as R is between 0.4 and 1.0.Under the optimized condition of R equals to 0.6,temperature of 1 250 ℃,slag melting point of 1 320 ℃,and time of 30 min,the metallization rate can reach 88.43%.展开更多
Isolated ruminal epithelia from caudal blind sacs of dairy goats were incubated with butyrate and insulin-like growth factor-1（IGF-1） at different concentrations. Proportions of ruminal epithelium in different phase...Isolated ruminal epithelia from caudal blind sacs of dairy goats were incubated with butyrate and insulin-like growth factor-1（IGF-1） at different concentrations. Proportions of ruminal epithelium in different phases of the cell division cycle were determined by flow cytometric analysis. The proportion of epithelial cells in S phase and G2-M phase（PS＆G2-M） increased significantly（P〈0.01） whereas the proportion of epithelial cells in G0-G1 phase（PG0-G1） decreased after incubation with IGF-1. PS＆G2-M decreased whereas PG0-G1 increased markedly（P〈0.01） after incubation with sodium butyrate. PS＆G2-M incubated with IGF-1 and butyrate sodium together increased more than that incubated with IGF-1 alone; PG0-G1, however, decreased significantly（P〈0.01）. Our results indicate that IGF-1 enhances whereas sodium butyrate inhibits the proliferation of rumen epithelial cells. Furthermore, butyrate and IGF-1, together, have a synergic effect on the proliferation of rumen epithelium.展开更多
Background Hearing impairment is one of the most common birth defects in children.Universal newborn hearing screenings have been performed for 19 years in Guangdong province,China.A screening/diagnosis/intervention sy...Background Hearing impairment is one of the most common birth defects in children.Universal newborn hearing screenings have been performed for 19 years in Guangdong province,China.A screening/diagnosis/intervention system has gradually been put in place.Over the past 10 years,a relatively complete data management system had been established.In the present study,an etiological analysis of newborn cases that failed the initial and follow-up screenings was performed.Methods The nature and degree of hearing impairment in newborns were confirmed by a set of procedures performed at the time of initial hearing screening,rescreening and final hearing diagnosis.Then,multiple examinations were performed to explore the associated etiology.Results Over a period of 10 years,720 children were diagnosed with newborn hearing loss.Among these children,445 (61.81%) children had a clearly identified cause,which included genetic factor(s) (30.56%),secretory otitis media (13.30%),maternal rubella virus infection during pregnancy (5.83%),inner ear malformations (4.86%),maternal human cytomegalovirus infection during pregnancy (2.92%),malformation of the middle ear ossicular chain (2.50%) and auditory neuropathy (1.81%).In addition,275 cases of sensorineural hearing loss of unknown etiology accounted for 38.19% of the children surveyed.Conclusions Long-term follow-up is needed to detect delayed hearing impairment and auditory development in children.The need for long-term follow-up should be taken into account when designing an intervention strategy.Furthermore,the use of the deafness gene chip should further elucidate the etiology of neonatal hearing impairment.展开更多
The high-altitude detection of astronomical radiation(HADAR)experiment is a new Cherenkov observation technique with a wide field of view(FoV),aimed at observing the prompt emissions ofγ-ray bursts(GRBs).The bottlene...The high-altitude detection of astronomical radiation(HADAR)experiment is a new Cherenkov observation technique with a wide field of view(FoV),aimed at observing the prompt emissions ofγ-ray bursts(GRBs).The bottleneck for this type of experiment can be found in determining how to reject the high rate of nightsky background(NSB)noise from random stars.In this work,we propose a novel method for rejecting noise,which considers the spatial properties of GRBs and the temporal characteristics of Cherenkov radiation.In space coordinates,the map between the celestial sphere and the fired photomultiplier tubes(PMTs)on the telescope's camera can be expressed as f(δ(i,j))=δ'(i',j'),which means that a limited number of PMTs is selected from one direction.On the temporal scale,a 20-ns time window was selected based on the knowledge of Cherenkov radiation.This allowed integration of the NSB for a short time interval.Consequently,the angular resolution and effective area at 100 GeV in the HADAR experiment were obtained as 0.2°and 10^(4)m^(2),respectively.This method can be applied to all wide-FoV experiments.展开更多
文摘The High Altitude Detection of Astronomical Radiation(HADAR)experiment,which was constructed in Tibet,China,combines the wide-angle advantages of traditional EAS array detectors with the high-sensitivity advantages of focused Cherenkov detectors.Its objective is to observe transient sources such as gamma-ray bursts and the counterparts of gravitational waves.This study aims to utilize the latest AI technology to enhance the sensitivity of HADAR experiments.Training datasets and models with distinctive creativity were constructed by incorporating the relevant physical theories for various applications.These models can determine the type,energy,and direction of the incident particles after careful design.We obtained a background identification accuracy of 98.6%,a relative energy reconstruction error of 10.0%,and an angular resolution of 0.22°in a test dataset at 10 TeV.These findings demonstrate the significant potential for enhancing the precision and dependability of detector data analysis in astrophysical research.By using deep learning techniques,the HADAR experiment’s observational sensitivity to the Crab Nebula has surpassed that of MAGIC and H.E.S.S.at energies below 0.5 TeV and remains competitive with conventional narrow-field Cherenkov telescopes at higher energies.In addition,our experiment offers a new approach for dealing with strongly connected,scattered data.
基金support from the National Natural Science Foundation of China(30960252)the earmarked fund for Modern Agro-Industry Technology Research System of China
文摘Six rumen-cannulated lactating Guanzhong goats were used to investigate changes in ruminal fermentation pattern and the microbiota following a subacute rtmainal acidosis （SARA） inducing procedure. Induction of SARA was performed by increasing dietary non-fiber carbohydrate （NFC） to neutral detergent fiber （NDF） ratio from 1.02 （stage 1） to 1.24 （stage 2）, 1.63 （stage 3） and 2.58 （stage 4）. A dynamic pH monitoring system, real-time fluorescent quantitative PCR and conventional anaerobic culture were used to assess changes in ruminal pH and microbiota. Results indicated that rumen fermentation patterns changed significantly with increased NFC：NDF ratio. The decline in ruminal pH was caused by increased ruminal total volatile fatty acids （TVFA）, which was mainly attributed to a significant increase in ruminal butyrate, rather than the accumulation of ruminal lactic acid. In addition, in the course of SARA, the number of rumen microoganisms altered significantly, with increases in ruminal amylolytic bacteria, Lactobacilli, Streptococcus bovis and Megasphaera elsdenii, the latter particularly dramatically indicating that it may be the main factor responsible for the increase in butyrate, and decrease in protozoa.
基金supported by the Central Government Funds for Local Scientific and Technological Development(grant No.JDRC2023000009)Tibet University Postgraduate Students’High-Level Talent Training Plan Project(grant No.2021-GSP-S038)。
文摘Ground-based arrays of imaging atmospheric Cherenkov telescopes(IACTs)are the most sensitiveγ-ray detectors for energies of approximately 100 Ge V and above.One such IACT is the High Altitude Detection of Astronomical Radiation(HADAR)experiment,which uses a large aperture refractive water lens system to capture atmospheric Cherenkov photons(i.e.,the imaging atmospheric Cherenkov technique).The telescope array has a low threshold energy and large field of view,and can continuously scan the area of the sky being observed,which is conducive to monitoring and promptly responding to transient phenomena.The process ofγ-hadron separation is essential in very-high-energy(>30 Ge V)γ-ray astronomy and is a key factor for the successful utilization of IACTs.In this study,Monte Carlo simulations were carried out to model the response of cosmic rays within the HADAR detectors.By analyzing the Hillas parameters and the distance between the event core and the telescope,the distinction between air showers initiated byγ-rays and those initiated by cosmic rays was determined.Additionally,a Quality Factor was introduced to assess the telescope’s ability to suppress the background and to provide a more effective characterization of its performance.
文摘The generation of polycyclic aromatic hydrocarbons （PAHs） during coking was studied and the contents of sixteen PAHs were measured by the devices of ultrasonic abstraction and high performance liquid chromatography for single coal coking and blended coal coking. The results indicated that the amount of generated PAHs during the first 1--4 h of coking is the most. Among these PAHs, the tetranuclear PAHs have a major portion and the Benzo[a]pyrene which can cause cancer, and teratogenesis and mutation is generated for a larger concentration more than emission standard value. Two PAHs are the main pollutants of PAHs pollution.
基金Supported by the National Natural Science Foundation of China(12263004,12263005,12275279)。
文摘The observation of short gamma ray bursts(SGRBs)in the TeV energy range plays an important role in understanding the radiation mechanism and probing potential new physics,such as Lorentz invariance violation(LIV).However,no SGRBs have been observed in this energy range owing to the short duration of SGRBs and the weakness of current experiments.New experiments with new technology are required to detect the very high energy(VHE)emission of SGRBs.In this study,we simulate the VHE γ-ray emissions from SGRBs and calculate the annu-al detection rate with the High Altitude Detection of Astronomical Radiation(HADAR)experiment.First,a set of pseudo-SGRB samples is generated and checked using the observations of the Fermi-GBM,Fermi-LAT,and Swift-BAT measurements.The annual detection rate is calculated from these SGRB samples based on the performance of the HADAR instrument.As a result,the HADAR experiment can detect 0.5 SGRBs per year if the spectral break-off of γ-rays caused by the internal absorption and Klein-Nishina(KN)effect is larger than 100 GeV.For a GRB090510-like GRB in HADAR's view,it should be possible to detect approximately 2000 photons considering the internal absorption and KN effect.With a time delay assumption due to LIV effects,a simulated light curve of GRB090510 has evident energy dependence.We hope that the HADAR experiment can perform SGRB observa-tions and test our calculations in the future.
基金Item Sponsored by National Science and Technology Support Program for 11th Five-Year Plan of China(2009BAB45B05)
文摘A lot of iron-bearing slags were produced,and whose grade is much more than that of industrial iron ore grade.Chemical analysis and phase identification shows that the iron-bearing slag is amorphous,has fayalite main phase,iron grade is 36.10%,and is difficult to recover iron from the slag.Thermodynamic calculation indicates that CO cannot reduce fayalite at high temperature and carbon direct reduction can be effective.Moreover,the reaction begins at 770 ℃ and the temperature can be reduced down to 500℃ when CaO is added.On this basis,a method is put forward to making direct enrichment of iron by taking carbon contained pellets to realize the rapid reduction of fayalite,and the direct reduction process were studied in this paper.Experiments show that xC/xO should be less than 1.5 for the need of reduction and carburization,and CaO and Al2O3 can spur the reduction of fayalite.On conditions that xC/xO is 1.2,metallization rate can be 77% when temperature is 1 250 ℃ and only carbon is added,and metallization rate can be 74% when temperature is 1 200 ℃ and only CaO is added.Moreover the addition of Al2O3 can get a higher metallization rate（10% or so） than usual as R is between 0.4 and 1.0.Under the optimized condition of R equals to 0.6,temperature of 1 250 ℃,slag melting point of 1 320 ℃,and time of 30 min,the metallization rate can reach 88.43%.
基金supported by the National Natural Science Foundation of China(30960252)the China Agriculture Research System(CARS-37)
文摘Isolated ruminal epithelia from caudal blind sacs of dairy goats were incubated with butyrate and insulin-like growth factor-1（IGF-1） at different concentrations. Proportions of ruminal epithelium in different phases of the cell division cycle were determined by flow cytometric analysis. The proportion of epithelial cells in S phase and G2-M phase（PS＆G2-M） increased significantly（P〈0.01） whereas the proportion of epithelial cells in G0-G1 phase（PG0-G1） decreased after incubation with IGF-1. PS＆G2-M decreased whereas PG0-G1 increased markedly（P〈0.01） after incubation with sodium butyrate. PS＆G2-M incubated with IGF-1 and butyrate sodium together increased more than that incubated with IGF-1 alone; PG0-G1, however, decreased significantly（P〈0.01）. Our results indicate that IGF-1 enhances whereas sodium butyrate inhibits the proliferation of rumen epithelial cells. Furthermore, butyrate and IGF-1, together, have a synergic effect on the proliferation of rumen epithelium.
基金This work was supported by the Guangdong Science and Technology Committee of China(Grant No.2015A020220005)Science and Technology Plan Project of Guangzhou City(Grant No.201704030081).
文摘Background Hearing impairment is one of the most common birth defects in children.Universal newborn hearing screenings have been performed for 19 years in Guangdong province,China.A screening/diagnosis/intervention system has gradually been put in place.Over the past 10 years,a relatively complete data management system had been established.In the present study,an etiological analysis of newborn cases that failed the initial and follow-up screenings was performed.Methods The nature and degree of hearing impairment in newborns were confirmed by a set of procedures performed at the time of initial hearing screening,rescreening and final hearing diagnosis.Then,multiple examinations were performed to explore the associated etiology.Results Over a period of 10 years,720 children were diagnosed with newborn hearing loss.Among these children,445 (61.81%) children had a clearly identified cause,which included genetic factor(s) (30.56%),secretory otitis media (13.30%),maternal rubella virus infection during pregnancy (5.83%),inner ear malformations (4.86%),maternal human cytomegalovirus infection during pregnancy (2.92%),malformation of the middle ear ossicular chain (2.50%) and auditory neuropathy (1.81%).In addition,275 cases of sensorineural hearing loss of unknown etiology accounted for 38.19% of the children surveyed.Conclusions Long-term follow-up is needed to detect delayed hearing impairment and auditory development in children.The need for long-term follow-up should be taken into account when designing an intervention strategy.Furthermore,the use of the deafness gene chip should further elucidate the etiology of neonatal hearing impairment.
基金supported by the Key R&D Program of Sichuan Province (Nos. 2019ZYZF0001 and 2020YFSY0016)the National Natural Science Foundation of China (Nos. 11873005,12047575, 11705103, 11635011, U1831208, U1632104, 11875264U2031110)
文摘The high-altitude detection of astronomical radiation(HADAR)experiment is a new Cherenkov observation technique with a wide field of view(FoV),aimed at observing the prompt emissions ofγ-ray bursts(GRBs).The bottleneck for this type of experiment can be found in determining how to reject the high rate of nightsky background(NSB)noise from random stars.In this work,we propose a novel method for rejecting noise,which considers the spatial properties of GRBs and the temporal characteristics of Cherenkov radiation.In space coordinates,the map between the celestial sphere and the fired photomultiplier tubes(PMTs)on the telescope's camera can be expressed as f(δ(i,j))=δ'(i',j'),which means that a limited number of PMTs is selected from one direction.On the temporal scale,a 20-ns time window was selected based on the knowledge of Cherenkov radiation.This allowed integration of the NSB for a short time interval.Consequently,the angular resolution and effective area at 100 GeV in the HADAR experiment were obtained as 0.2°and 10^(4)m^(2),respectively.This method can be applied to all wide-FoV experiments.
