BACKGROUND In an era leaning toward a personalized alignment of total knee arthroplasty,coronal plane alignment of the knee(CPAK)phenotypes for each population are studied;furthermore,other possible variables affectin...BACKGROUND In an era leaning toward a personalized alignment of total knee arthroplasty,coronal plane alignment of the knee(CPAK)phenotypes for each population are studied;furthermore,other possible variables affecting the alignment,such as ankle joint alignment,should be considered.AIM To determine CPAK distribution in the North African(Egyptian)population with knee osteoarthritis and to assess ankle joint line orientation(AJLO)adaptations across different CPAK types.METHODS A cross-sectional study was conducted on patients with primary knee osteoarthritis and normal ankle joints.Radiographic parameters included the mechanical lateral distal femoral angle,medial proximal tibial angle,and the derived calculations of joint line obliquity(JLO)and arithmetic hip-knee-ankle angle(aHKA).The tibial plafond horizontal angle(TPHA)was used for AJLO assessment,where 0°is neutral(type N),<0°is varus(type A),and>0°is valgus(type B).The nine CPAK types were further divided into 27 subtypes after incorporating the three AJLO types.RESULTS A total of 527 patients(1054 knees)were included for CPAK classification,and 435 patients(870 knees and ankles)for AJLO assessment.The mean age was 57.2±7.8 years,with 79.5%females.Most knees(76.4%)demonstrated varus alignment(mean aHKA was-5.51°±4.84°)and apex distal JLO(55.3%)(mean JLO was 176.43°±4.53°).CPAK types I(44.3%),IV(28.6%),and II(10%)were the most common.Regarding AJLO,70.2%of ankles exhibited varus orientation(mean TPHA was-5.21°±6.45°).The most frequent combined subtypes were CPAK type I-A(33.7%),IV-A(21.5%),and I-N(6.9%).A significant positive correlation was found between the TPHA and aHKA(r=0.40,P<0.001).CONCLUSION In this North African cohort,varus knee alignment with apex distal JLO and varus AJLO predominated.CPAK types I,IV,and II were the most common types,while subtypes I-A,IV-A,and I-N were commonly occurring after incorporating AJLO types;furthermore,the AJLO was significantly correlated to aHKA.展开更多
Using the correlation between the radiance or Doppler velocity and the extrapolated magnetic field, we determined the emission heights of a set of solar transition region lines in an equatorial coronal hole and in the...Using the correlation between the radiance or Doppler velocity and the extrapolated magnetic field, we determined the emission heights of a set of solar transition region lines in an equatorial coronal hole and in the surrounding quiet Sun region. We found that for all of the six lower-transition-region lines, the emission height is about 4-5 Mm in the equatorial coronal hole, and around 2 Mm in the quiet Sun region. This result confirms the previous findings that plasma with different temperature can coexist at the same layer of transition region. In the quiet Sun region, the emission height of the upper-transition-region line Ne VIII is almost the same that of the lower-transition-region line, but in the coronal hole, it is twice as high. This difference reveals that the outflow of Ne VIII is a signature of solar wind in the coronal hole and is just a mass supply to the large loops in the quiet Sun.展开更多
In this article,we compare the properties of two coronal mass ejections(CMEs)that show similar source region characteristics but different evolutionary behaviors in the later phases.We discuss the two events in terms ...In this article,we compare the properties of two coronal mass ejections(CMEs)that show similar source region characteristics but different evolutionary behaviors in the later phases.We discuss the two events in terms of their near-Sun characteristics,interplanetary evolution and geoeffectiveness.We carefully analyzed the initiation and propagation parameters of these events to establish the precise CMEinterplanetary CME(ICME)connection and their near-Earth consequences.The first event is associated with poor geomagnetic storm disturbance index(Dst≈-20 n T)while the second event is associated with an intense geomagnetic storm of DST≈-119 n T.The configuration of the sunspots in the active regions and their evolution are observed by Helioseismic and Magnetic Imager(HMI).For source region imaging,we rely on data obtained from Atmospheric Imaging Assembly(AIA)on board Solar Dynamics Observatory(SDO)and Hαfiltergrams from the Solar Tower Telescope at Aryabhatta Research Institute of Observational Sciences(ARIES).For both the CMEs,flux rope eruptions from the source region triggered flares of similar intensities(≈M1).At the solar source region of the eruptions,we observed a circular ribbon flare(CRF)for both cases,suggesting fan-spine magnetic configuration in the active region corona.The multi-channel SDO observations confirm that the eruptive flares and subsequent CMEs were intimately related to the filament eruption.Within the Large Angle and Spectrometric Coronograph(LASCO)field of view(FOV)the two CMEs propagated with linear speeds of 671 and 631 km s-1,respectively.These CMEs were tracked up to the Earth by Solar Terrestrial Relations Observatory(STEREO)instruments.We find that the source region evolution of CMEs,guided by the large-scale coronal magnetic field configuration,along with near-Sun propagation characteristics,such as CME-CME interactions,played important roles in deciding the evolution of CMEs in the interplanetary medium and subsequently their geoeffectiveness.展开更多
The origin of the heliospheric magnetic flux on the Sun,and hence the origin of the solar wind,is a topic of hot debate.While the prevailing view is that the solar wind originates from outside the coronal streamer hel...The origin of the heliospheric magnetic flux on the Sun,and hence the origin of the solar wind,is a topic of hot debate.While the prevailing view is that the solar wind originates from outside the coronal streamer helmets,there also exists the suggestion that the open magnetic field spans a far wider region.Without the definitive measurement of the coronal magnetic field,it is difficult to unambiguously resolve the conflict between the two scenarios.We present two 2-dimensional, Alfvénic-turbulence-based models of the solar corona and solar wind,one with and the other without a closed magnetic field region in the inner corona.The purpose of the latter model is to test whether it is possible to realize a picture suggested by polarimetric measurements of the corona using the Fe XⅢ 10747 line,where open magnetic field lines seem to penetrate the streamer base.The boundary conditions at the coronal base are able to account for important observational constraints,especially those on the magnetic flux distribution.Interestingly,the two models provide similar polarized brightness（pB）distributions in the field of view（FOV）of SOHO/LASCO C2 and C3 coronagraphs.In particular,a dome-shaped feature is present in the C2 FOV even for the model without a closed magnetic field.Moreover,both models fit the Ulysses data scaled to 1 AU equally well.We suggest that：1）The pB observations cannot be safely taken as a proxy for the magnetic field topology,as is often implicitly assumed.2）The Ulysses measurements,especially the one showing a nearly uniform distribution with heliocentric latitude of the radial magnetic field,do not rule out the ubiquity of open magnetic fields on the Sun.展开更多
The atmospheric activity of the Sun and Sun-like stars is analyzed involving observations from the HK-project at the Mount Wilson Observatory, the California and Carnegie Planet Search Program at the Keck and Lick Obs...The atmospheric activity of the Sun and Sun-like stars is analyzed involving observations from the HK-project at the Mount Wilson Observatory, the California and Carnegie Planet Search Program at the Keck and Lick Observatories and the Magellan Planet Search Program at the Las Campanas Observatory. We show that for stars of E G and K spectral classes, the cyclic activity, similar to the 11-yr solar cycle, is different： it becomes more prominent in K-stars. Comparative study of Sun-like stars with different levels of chromospheric and coronal activity confirms that the Sun belongs to stars with a low level of chromospheric activity and stands apart among these stars by its minimum level of coronal radiation and minimum level of variations in photospheric flux.展开更多
This study analyzes the evolution and dynamics of intensity oscillations in coronal sunspots and their surroundings using multi-wavelength image data from the Atmospheric Imaging Assembly(AIA)and Helioseismic and Magn...This study analyzes the evolution and dynamics of intensity oscillations in coronal sunspots and their surroundings using multi-wavelength image data from the Atmospheric Imaging Assembly(AIA)and Helioseismic and Magnetic Imager(HMI)on board the Solar Dynamics Observatory(SDO).Intensity time series were extracted and analyzed from consecutive macropixels along thin coronal loop paths originating in a quiet sunspot.Fourier and wavelet analyses of corrected intensity time series reveal dominant 3 and 5 minute oscillations.Signals were filtered using the Fourier and inverse transforms to isolate narrow bands around the dominant oscillation periods.Diagrams and time-distance maps of intensity time series were plotted for Fourierfiltered AIA 131A,171A,193A,and 211A channels,along with SDO/HMI magnetograms and dopplergrams at 6173A.The plots clearly show propagating oscillations with amplitude modulation(AM)across all macropixels along selected coronal paths in nearly all AIA and HMI channels.The phase speeds of the filtered oscillations,measured via slope calculations in time-distance maps,indicate that the intensity disturbances are slow magneto-acoustic waves.These results suggest that AM likely arises from the superposition of counterpropagating waves with slightly different frequencies(beta-like phenomena)due to Doppler shifts from background plasma flow along loop paths.Validating this hypothesis could establish AM's significance in solar coronal seismology for determining background plasma flow speed,the source of long-period oscillations,and coronal plasma heating mechanisms.展开更多
In winter,the weather is usually cold and everything seems a bit dull.Butthe sun in winter is special.When the sun shines brightly in the clear blue sky,it brings warm(1)to thecold world.The golden sunlight spreads he...In winter,the weather is usually cold and everything seems a bit dull.Butthe sun in winter is special.When the sun shines brightly in the clear blue sky,it brings warm(1)to thecold world.The golden sunlight spreads here and there and it makes the whitesnow shine like diamonds.Although the trees are usually bare in winter,but(2)they look beautiful with the sunlight falling on them.展开更多
BACKGROUND Back pain and sciatica are common complaints that often require imaging for accurate diagnosis and management.Conventional lumbar magnetic resonance imaging(MRI)protocols typically include sagittal and axia...BACKGROUND Back pain and sciatica are common complaints that often require imaging for accurate diagnosis and management.Conventional lumbar magnetic resonance imaging(MRI)protocols typically include sagittal and axial T1 and T2 sequences;however,these may miss certain pathologies.The addition of coronal short tau inversion recovery(STIR)sequences offers the potential to enhance the detection of both spinal and extra-spinal abnormalities,thereby improving clinical decisionmaking and patient outcomes.AIM To evaluate the impact of adding coronal STIR sequences to routine lumbar MRI in diagnosing back pain and sciatica.METHODS We prospectively analyzed data from patients aged 6 and older presenting with back pain or sciatica who underwent lumbar spine MRI at our institution.The standardized MRI protocol utilized included sagittal and axial T1 and T2 sequences,complemented by a coronal STIR sequence.Data on structural abnormalities were collected,reviewed,and analyzed using counts,percentages,and Fisher's exact test for categorical variables.RESULTS Our cohort comprised 274 patients(115 males,159 females;mean age 44.91 years).Notably,39 patients exhibited abnormalities across all sequences,while 72.63%showed normal findings on the coronal STIR sequence.Importantly,30.29%of cases were diagnosed as normal without the coronal STIR,and 36 patients with normal T1 and T2 sequences presented abnormalities on the coronal STIR.The coronal STIR sequence successfully identified 26 spinal and 10 non-spinal pathologies,including 17 cases of sacroiliitis,with a significant association(P<0.0001)between sacroiliitis diagnosis and abnormalities visible solely on this sequence.CONCLUSION Integrating coronal STIR into routine lumbar MRI enhances detection of hidden spinal and extra-spinal pathologies,improves patient management,and offers a cost-effective,practical upgrade with significant diagnostic and clinical value.展开更多
Recent observations have demonstrated the capability of mapping the solar coronal magnetic field using the technique of coronal seismology based on the ubiquitous propagating Alfvénic/kink waves through imaging s...Recent observations have demonstrated the capability of mapping the solar coronal magnetic field using the technique of coronal seismology based on the ubiquitous propagating Alfvénic/kink waves through imaging spectroscopy.We established a magnetohydrodynamic model of a gravitationally stratified open magnetic flux tube,exciting kink waves propagating upwards along the tube.Forward modeling was performed to synthesize the Fe XIII 1074.7 and 1079.8 nm spectral line profiles,which were then used to determine the wave phase speed,plasma density,and magnetic field with seismology method.A comparison between the seismologically inferred results and the corresponding input values verifies the reliability of the seismology method.In addition,we also identified some factors that could lead to errors during magnetic field measurements.Our results may serve as a valuable reference for current and future coronal magnetic field measurements based on observations of propagating kink waves.展开更多
The large-aperture reflective cameras on the geostationary orbit are susceptible to significant temperature fluctuations due to the“Sun transit”effect.To address the shortcomings of existing thermal control measures...The large-aperture reflective cameras on the geostationary orbit are susceptible to significant temperature fluctuations due to the“Sun transit”effect.To address the shortcomings of existing thermal control measures using camera sunshades to suppress the“Sun transit”and the issue of excessively large solar avoidance angles determined solely by geometric relationships,a thermal control design method is proposed that involves adding multi-layer thermal protection at the secondary mirror position of the camera.The goal is to optimize the avoidance angle and enhance the camera’s tolerance to“Sun transit”.A heat balance and motion relationship between the avoidance angle and duration is established.Then,the minimum solar avoidance angle after adopting the multi-layer thermal protection design is calculated.This angle is compared with the one determined by geometric relationships,leading to the conclusion that this method can effectively enhance the camera’s tolerance to“Sun transit”.A heat dissipation scheme is proposed that involves a coupled north-south heat spreader design with low-temperature compensation for the internal heat source.The calculation results of the two avoidance angles are applied to the calculation of the heat dissipation area and low-temperature compensation power,achieving a closed-loop heat dissipation scheme.Puls,the superiority of the multi-layer thermal protection design method is demonstrated from the perspectives of heat dissipation area and low-temperature compensation power requirements.A comparative analysis of simulation analysis,thermal balance tests,and in-orbit temperature data further validates the effectiveness of this method.展开更多
Sun Chemical将提高其在欧洲、中东和非洲(EMEA)的多种油墨产品组合的价格,立即生效。近几个月来,彩色和白色颜料的供应链受到各种挑战的严重影响,包括中断、短缺、破产、反倾销进口税以及来自亚洲的海运费进一步上涨。这些因素一直推...Sun Chemical将提高其在欧洲、中东和非洲(EMEA)的多种油墨产品组合的价格,立即生效。近几个月来,彩色和白色颜料的供应链受到各种挑战的严重影响,包括中断、短缺、破产、反倾销进口税以及来自亚洲的海运费进一步上涨。这些因素一直推高了太阳化学油墨产品的成本,包括彩色和白色油墨。展开更多
基金approved by Institutional Review Board of Faculty of Medicine in Assiut University,No.04-2024-300470.
文摘BACKGROUND In an era leaning toward a personalized alignment of total knee arthroplasty,coronal plane alignment of the knee(CPAK)phenotypes for each population are studied;furthermore,other possible variables affecting the alignment,such as ankle joint alignment,should be considered.AIM To determine CPAK distribution in the North African(Egyptian)population with knee osteoarthritis and to assess ankle joint line orientation(AJLO)adaptations across different CPAK types.METHODS A cross-sectional study was conducted on patients with primary knee osteoarthritis and normal ankle joints.Radiographic parameters included the mechanical lateral distal femoral angle,medial proximal tibial angle,and the derived calculations of joint line obliquity(JLO)and arithmetic hip-knee-ankle angle(aHKA).The tibial plafond horizontal angle(TPHA)was used for AJLO assessment,where 0°is neutral(type N),<0°is varus(type A),and>0°is valgus(type B).The nine CPAK types were further divided into 27 subtypes after incorporating the three AJLO types.RESULTS A total of 527 patients(1054 knees)were included for CPAK classification,and 435 patients(870 knees and ankles)for AJLO assessment.The mean age was 57.2±7.8 years,with 79.5%females.Most knees(76.4%)demonstrated varus alignment(mean aHKA was-5.51°±4.84°)and apex distal JLO(55.3%)(mean JLO was 176.43°±4.53°).CPAK types I(44.3%),IV(28.6%),and II(10%)were the most common.Regarding AJLO,70.2%of ankles exhibited varus orientation(mean TPHA was-5.21°±6.45°).The most frequent combined subtypes were CPAK type I-A(33.7%),IV-A(21.5%),and I-N(6.9%).A significant positive correlation was found between the TPHA and aHKA(r=0.40,P<0.001).CONCLUSION In this North African cohort,varus knee alignment with apex distal JLO and varus AJLO predominated.CPAK types I,IV,and II were the most common types,while subtypes I-A,IV-A,and I-N were commonly occurring after incorporating AJLO types;furthermore,the AJLO was significantly correlated to aHKA.
基金Hui Tian, Jian-Sen He, Bo Tan, and Shuo Yao are supported by the National Natural Science Foundation of China under Grants 40574078, 40336053 and40436015by the Beijing Education Project XK100010404+4 种基金the foundation Major Project of National Basic Research, under contract 2006CB806305Hui Tian is also supported by China Scholarship Council for his stay in the Max-Planck-Institut fr Sonnen system for schung in GermanyLi-Dong Xia is supported by the National Natural Science Foundation of China under Grant 40574064the Programme for New Century Excellent Talents in University (NCET)supported by DLR, CNES, NASA, and the ESA PRODEX programme (Swiss contribution).
文摘Using the correlation between the radiance or Doppler velocity and the extrapolated magnetic field, we determined the emission heights of a set of solar transition region lines in an equatorial coronal hole and in the surrounding quiet Sun region. We found that for all of the six lower-transition-region lines, the emission height is about 4-5 Mm in the equatorial coronal hole, and around 2 Mm in the quiet Sun region. This result confirms the previous findings that plasma with different temperature can coexist at the same layer of transition region. In the quiet Sun region, the emission height of the upper-transition-region line Ne VIII is almost the same that of the lower-transition-region line, but in the coronal hole, it is twice as high. This difference reveals that the outflow of Ne VIII is a signature of solar wind in the coronal hole and is just a mass supply to the large loops in the quiet Sun.
文摘In this article,we compare the properties of two coronal mass ejections(CMEs)that show similar source region characteristics but different evolutionary behaviors in the later phases.We discuss the two events in terms of their near-Sun characteristics,interplanetary evolution and geoeffectiveness.We carefully analyzed the initiation and propagation parameters of these events to establish the precise CMEinterplanetary CME(ICME)connection and their near-Earth consequences.The first event is associated with poor geomagnetic storm disturbance index(Dst≈-20 n T)while the second event is associated with an intense geomagnetic storm of DST≈-119 n T.The configuration of the sunspots in the active regions and their evolution are observed by Helioseismic and Magnetic Imager(HMI).For source region imaging,we rely on data obtained from Atmospheric Imaging Assembly(AIA)on board Solar Dynamics Observatory(SDO)and Hαfiltergrams from the Solar Tower Telescope at Aryabhatta Research Institute of Observational Sciences(ARIES).For both the CMEs,flux rope eruptions from the source region triggered flares of similar intensities(≈M1).At the solar source region of the eruptions,we observed a circular ribbon flare(CRF)for both cases,suggesting fan-spine magnetic configuration in the active region corona.The multi-channel SDO observations confirm that the eruptive flares and subsequent CMEs were intimately related to the filament eruption.Within the Large Angle and Spectrometric Coronograph(LASCO)field of view(FOV)the two CMEs propagated with linear speeds of 671 and 631 km s-1,respectively.These CMEs were tracked up to the Earth by Solar Terrestrial Relations Observatory(STEREO)instruments.We find that the source region evolution of CMEs,guided by the large-scale coronal magnetic field configuration,along with near-Sun propagation characteristics,such as CME-CME interactions,played important roles in deciding the evolution of CMEs in the interplanetary medium and subsequently their geoeffectiveness.
基金supported by the National Natural Science Foundation of China(Grant Nos.40904047and 41174154)the Ministry of Education of China(20110131110058 and NCET-11-0305)by the Specialized Research Fund for State Key Laboratories
文摘The origin of the heliospheric magnetic flux on the Sun,and hence the origin of the solar wind,is a topic of hot debate.While the prevailing view is that the solar wind originates from outside the coronal streamer helmets,there also exists the suggestion that the open magnetic field spans a far wider region.Without the definitive measurement of the coronal magnetic field,it is difficult to unambiguously resolve the conflict between the two scenarios.We present two 2-dimensional, Alfvénic-turbulence-based models of the solar corona and solar wind,one with and the other without a closed magnetic field region in the inner corona.The purpose of the latter model is to test whether it is possible to realize a picture suggested by polarimetric measurements of the corona using the Fe XⅢ 10747 line,where open magnetic field lines seem to penetrate the streamer base.The boundary conditions at the coronal base are able to account for important observational constraints,especially those on the magnetic flux distribution.Interestingly,the two models provide similar polarized brightness（pB）distributions in the field of view（FOV）of SOHO/LASCO C2 and C3 coronagraphs.In particular,a dome-shaped feature is present in the C2 FOV even for the model without a closed magnetic field.Moreover,both models fit the Ulysses data scaled to 1 AU equally well.We suggest that：1）The pB observations cannot be safely taken as a proxy for the magnetic field topology,as is often implicitly assumed.2）The Ulysses measurements,especially the one showing a nearly uniform distribution with heliocentric latitude of the radial magnetic field,do not rule out the ubiquity of open magnetic fields on the Sun.
文摘The atmospheric activity of the Sun and Sun-like stars is analyzed involving observations from the HK-project at the Mount Wilson Observatory, the California and Carnegie Planet Search Program at the Keck and Lick Observatories and the Magellan Planet Search Program at the Las Campanas Observatory. We show that for stars of E G and K spectral classes, the cyclic activity, similar to the 11-yr solar cycle, is different： it becomes more prominent in K-stars. Comparative study of Sun-like stars with different levels of chromospheric and coronal activity confirms that the Sun belongs to stars with a low level of chromospheric activity and stands apart among these stars by its minimum level of coronal radiation and minimum level of variations in photospheric flux.
文摘This study analyzes the evolution and dynamics of intensity oscillations in coronal sunspots and their surroundings using multi-wavelength image data from the Atmospheric Imaging Assembly(AIA)and Helioseismic and Magnetic Imager(HMI)on board the Solar Dynamics Observatory(SDO).Intensity time series were extracted and analyzed from consecutive macropixels along thin coronal loop paths originating in a quiet sunspot.Fourier and wavelet analyses of corrected intensity time series reveal dominant 3 and 5 minute oscillations.Signals were filtered using the Fourier and inverse transforms to isolate narrow bands around the dominant oscillation periods.Diagrams and time-distance maps of intensity time series were plotted for Fourierfiltered AIA 131A,171A,193A,and 211A channels,along with SDO/HMI magnetograms and dopplergrams at 6173A.The plots clearly show propagating oscillations with amplitude modulation(AM)across all macropixels along selected coronal paths in nearly all AIA and HMI channels.The phase speeds of the filtered oscillations,measured via slope calculations in time-distance maps,indicate that the intensity disturbances are slow magneto-acoustic waves.These results suggest that AM likely arises from the superposition of counterpropagating waves with slightly different frequencies(beta-like phenomena)due to Doppler shifts from background plasma flow along loop paths.Validating this hypothesis could establish AM's significance in solar coronal seismology for determining background plasma flow speed,the source of long-period oscillations,and coronal plasma heating mechanisms.
文摘In winter,the weather is usually cold and everything seems a bit dull.Butthe sun in winter is special.When the sun shines brightly in the clear blue sky,it brings warm(1)to thecold world.The golden sunlight spreads here and there and it makes the whitesnow shine like diamonds.Although the trees are usually bare in winter,but(2)they look beautiful with the sunlight falling on them.
文摘BACKGROUND Back pain and sciatica are common complaints that often require imaging for accurate diagnosis and management.Conventional lumbar magnetic resonance imaging(MRI)protocols typically include sagittal and axial T1 and T2 sequences;however,these may miss certain pathologies.The addition of coronal short tau inversion recovery(STIR)sequences offers the potential to enhance the detection of both spinal and extra-spinal abnormalities,thereby improving clinical decisionmaking and patient outcomes.AIM To evaluate the impact of adding coronal STIR sequences to routine lumbar MRI in diagnosing back pain and sciatica.METHODS We prospectively analyzed data from patients aged 6 and older presenting with back pain or sciatica who underwent lumbar spine MRI at our institution.The standardized MRI protocol utilized included sagittal and axial T1 and T2 sequences,complemented by a coronal STIR sequence.Data on structural abnormalities were collected,reviewed,and analyzed using counts,percentages,and Fisher's exact test for categorical variables.RESULTS Our cohort comprised 274 patients(115 males,159 females;mean age 44.91 years).Notably,39 patients exhibited abnormalities across all sequences,while 72.63%showed normal findings on the coronal STIR sequence.Importantly,30.29%of cases were diagnosed as normal without the coronal STIR,and 36 patients with normal T1 and T2 sequences presented abnormalities on the coronal STIR.The coronal STIR sequence successfully identified 26 spinal and 10 non-spinal pathologies,including 17 cases of sacroiliitis,with a significant association(P<0.0001)between sacroiliitis diagnosis and abnormalities visible solely on this sequence.CONCLUSION Integrating coronal STIR into routine lumbar MRI enhances detection of hidden spinal and extra-spinal pathologies,improves patient management,and offers a cost-effective,practical upgrade with significant diagnostic and clinical value.
基金supported by the National Natural Science Foundation of China (NSFC,grant No.12425301)the Strategic Priority Research Program of the Chinese Academy of Sciences (grant No.XDB0560000)+6 种基金the National Key R&D Program of China No.2022YFF0503800support from the National Natural Science Foundation of China (NSFC,grant No.12203030)supported by the C1 grant TRACEspace of Internal Funds KU Leuven and a Senior Research Project (G088021N) of the FWO Vlaanderensupport from the Flemish Government under the long-term structural Methusalem funding program,project SOUL:Stellar evolution in full glory,grant METH/24/012 at KU Leuvensubsidized by the Belgian Federal Science Policy Office through the contract B2/223/P1/CLOSE-UPfunding under the Horizon Europe program of the European Union under grant agreement (No.101131534)support by an FWO (Fonds voor Wetenschappelijk Onderzoek-Vlaanderen)postdoctoral fellowship (1273221N)
文摘Recent observations have demonstrated the capability of mapping the solar coronal magnetic field using the technique of coronal seismology based on the ubiquitous propagating Alfvénic/kink waves through imaging spectroscopy.We established a magnetohydrodynamic model of a gravitationally stratified open magnetic flux tube,exciting kink waves propagating upwards along the tube.Forward modeling was performed to synthesize the Fe XIII 1074.7 and 1079.8 nm spectral line profiles,which were then used to determine the wave phase speed,plasma density,and magnetic field with seismology method.A comparison between the seismologically inferred results and the corresponding input values verifies the reliability of the seismology method.In addition,we also identified some factors that could lead to errors during magnetic field measurements.Our results may serve as a valuable reference for current and future coronal magnetic field measurements based on observations of propagating kink waves.
基金supported by the Na⁃tional Key Research and Development Program of China(No.2021YFC2202102)。
文摘The large-aperture reflective cameras on the geostationary orbit are susceptible to significant temperature fluctuations due to the“Sun transit”effect.To address the shortcomings of existing thermal control measures using camera sunshades to suppress the“Sun transit”and the issue of excessively large solar avoidance angles determined solely by geometric relationships,a thermal control design method is proposed that involves adding multi-layer thermal protection at the secondary mirror position of the camera.The goal is to optimize the avoidance angle and enhance the camera’s tolerance to“Sun transit”.A heat balance and motion relationship between the avoidance angle and duration is established.Then,the minimum solar avoidance angle after adopting the multi-layer thermal protection design is calculated.This angle is compared with the one determined by geometric relationships,leading to the conclusion that this method can effectively enhance the camera’s tolerance to“Sun transit”.A heat dissipation scheme is proposed that involves a coupled north-south heat spreader design with low-temperature compensation for the internal heat source.The calculation results of the two avoidance angles are applied to the calculation of the heat dissipation area and low-temperature compensation power,achieving a closed-loop heat dissipation scheme.Puls,the superiority of the multi-layer thermal protection design method is demonstrated from the perspectives of heat dissipation area and low-temperature compensation power requirements.A comparative analysis of simulation analysis,thermal balance tests,and in-orbit temperature data further validates the effectiveness of this method.
