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
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
Pathological cardiac hypertrophy contributes to the development of heart failure(HF).NOL1/NOP2/Sun domain family member 2(NSUN2)is implicated in pathophysiological processes of many diseases.However,the function and o...Pathological cardiac hypertrophy contributes to the development of heart failure(HF).NOL1/NOP2/Sun domain family member 2(NSUN2)is implicated in pathophysiological processes of many diseases.However,the function and operation of NSUN2 in cardiac hypertrophy and HF remain unclear.Here,we observed a significant increase in the levels of NSUN2 expression in both human hearts with HF and in mouse hearts with hypertrophy induced by transverse aortic constriction(TAC)and angiotensin II(Ang II)treatment.Cardiomyocyte-specific knockout of NSUN2 attenuated the reduced cardiac ejection fraction(EF)and fractional shortening(FS)and the increased heart weight to tibial length(HW/TL)upon either TAC or Ang II infusion.Conversely,cardiac-specific overexpression of NSUN2 resulted in cardiac remodeling as indicated by a prominent increase in hypertrophic growth and cardiac fibrosis and a robust decline in cardiac EF and FS.Mechanistically,NSUN2 induces 5-methylcytosine(m5C)modification of La-related protein 1(LARP1)to enhance its messenger RNA(mRNA)stability,which is mediated by Y-box binding protein 1(YBX1).Increased LARP1 further interacts with GATA binding protein 4(GATA4)mRNA and prevents its degradation.LARP1 silencing partially attenuates TAC and NSUN2 induced cardiac hypertrophy and HF.Collectively,this study provides a new insight into the central role of NSUN2 in cardiac hypertrophy,indicating that NSUN2 may serve as a novel therapeutic target for HF.展开更多
In this study, we examined variability of sun-related energies, auroral electrojet current, ring current, and magnetopause current during solar cycles 23 and 24. The study revealed a dependence of sun-related energies...In this study, we examined variability of sun-related energies, auroral electrojet current, ring current, and magnetopause current during solar cycles 23 and 24. The study revealed a dependence of sun-related energies to the Sun and Earth currents systems with solar activity from 1996 to 2019. A decrease in the correlation between sun-related energies and sunspot number was observed over solar cycles 23 and 24 (0.88 for the solar cycle 23 and 0.66 for the solar cycle 24), with a drop in the speed of magnetic disturbances in the solar wind. These results could be attributed to the decrease in Sun’s magnetic field toroidal component magnitude induced by a weak in sunspots number and solar flares during the solar cycle 24. A weak in the Earth currents systems (auroral electrojet current, ring current, and magnetopause current) is also observed. During the decrease in the Earth currents, several peaks are observed, indicating a nonlinear dependence in the Earth currents variation (ring current, auroral electrojet current, and magnetopause current) from solar cycle 23 to solar cycle 24. This could be attributed to the Corotating Interaction Regions (CIRs) observed during the declining phase of solar cycle 23 and the deep minimum preceding solar cycle 24.展开更多
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.
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.
基金supported by grants from the Noncommunicable Chronic Diseases-National Science and Technology Major Project(2024ZD0537909)the National Natural Science Foundation of China(82273928,82473919,82330011,82161148007)+2 种基金the Distinguished Young Scholars of Natural Science Foundation of Heilongjiang Province(JQ2024H002)the Chunyan Programme of Heilongjiang Province(CYQN2403)the CAMS Innovation Fund for Medical Sciences(CIFMS,2020-I2M-5-003).
文摘Pathological cardiac hypertrophy contributes to the development of heart failure(HF).NOL1/NOP2/Sun domain family member 2(NSUN2)is implicated in pathophysiological processes of many diseases.However,the function and operation of NSUN2 in cardiac hypertrophy and HF remain unclear.Here,we observed a significant increase in the levels of NSUN2 expression in both human hearts with HF and in mouse hearts with hypertrophy induced by transverse aortic constriction(TAC)and angiotensin II(Ang II)treatment.Cardiomyocyte-specific knockout of NSUN2 attenuated the reduced cardiac ejection fraction(EF)and fractional shortening(FS)and the increased heart weight to tibial length(HW/TL)upon either TAC or Ang II infusion.Conversely,cardiac-specific overexpression of NSUN2 resulted in cardiac remodeling as indicated by a prominent increase in hypertrophic growth and cardiac fibrosis and a robust decline in cardiac EF and FS.Mechanistically,NSUN2 induces 5-methylcytosine(m5C)modification of La-related protein 1(LARP1)to enhance its messenger RNA(mRNA)stability,which is mediated by Y-box binding protein 1(YBX1).Increased LARP1 further interacts with GATA binding protein 4(GATA4)mRNA and prevents its degradation.LARP1 silencing partially attenuates TAC and NSUN2 induced cardiac hypertrophy and HF.Collectively,this study provides a new insight into the central role of NSUN2 in cardiac hypertrophy,indicating that NSUN2 may serve as a novel therapeutic target for HF.
文摘In this study, we examined variability of sun-related energies, auroral electrojet current, ring current, and magnetopause current during solar cycles 23 and 24. The study revealed a dependence of sun-related energies to the Sun and Earth currents systems with solar activity from 1996 to 2019. A decrease in the correlation between sun-related energies and sunspot number was observed over solar cycles 23 and 24 (0.88 for the solar cycle 23 and 0.66 for the solar cycle 24), with a drop in the speed of magnetic disturbances in the solar wind. These results could be attributed to the decrease in Sun’s magnetic field toroidal component magnitude induced by a weak in sunspots number and solar flares during the solar cycle 24. A weak in the Earth currents systems (auroral electrojet current, ring current, and magnetopause current) is also observed. During the decrease in the Earth currents, several peaks are observed, indicating a nonlinear dependence in the Earth currents variation (ring current, auroral electrojet current, and magnetopause current) from solar cycle 23 to solar cycle 24. This could be attributed to the Corotating Interaction Regions (CIRs) observed during the declining phase of solar cycle 23 and the deep minimum preceding solar cycle 24.
