Due to the lack of long-range association and spatial location information,fine details and accurate boundaries of complex clothing images cannot always be obtained by using the existing deep learning-based methods.Th...Due to the lack of long-range association and spatial location information,fine details and accurate boundaries of complex clothing images cannot always be obtained by using the existing deep learning-based methods.This paper presents a convolutional structure with multi-scale fusion to optimize the step of clothing feature extraction and a self-attention module to capture long-range association information.The structure enables the self-attention mechanism to directly participate in the process of information exchange through the down-scaling projection operation of the multi-scale framework.In addition,the improved self-attention module introduces the extraction of 2-dimensional relative position information to make up for its lack of ability to extract spatial position features from clothing images.The experimental results based on the colorful fashion parsing dataset(CFPD)show that the proposed network structure achieves 53.68%mean intersection over union(mIoU)and has better performance on the clothing parsing task.展开更多
Fault diagnosis is important for maintaining the safety and effectiveness of chemical process.Considering the multivariate,nonlinear,and dynamic characteristic of chemical process,many time-series-based data-driven fa...Fault diagnosis is important for maintaining the safety and effectiveness of chemical process.Considering the multivariate,nonlinear,and dynamic characteristic of chemical process,many time-series-based data-driven fault diagnosis methods have been developed in recent years.However,the existing methods have the problem of long-term dependency and are difficult to train due to the sequential way of training.To overcome these problems,a novel fault diagnosis method based on time-series and the hierarchical multihead self-attention(HMSAN)is proposed for chemical process.First,a sliding window strategy is adopted to construct the normalized time-series dataset.Second,the HMSAN is developed to extract the time-relevant features from the time-series process data.It improves the basic self-attention model in both width and depth.With the multihead structure,the HMSAN can pay attention to different aspects of the complicated chemical process and obtain the global dynamic features.However,the multiple heads in parallel lead to redundant information,which cannot improve the diagnosis performance.With the hierarchical structure,the redundant information is reduced and the deep local time-related features are further extracted.Besides,a novel many-to-one training strategy is introduced for HMSAN to simplify the training procedure and capture the long-term dependency.Finally,the effectiveness of the proposed method is demonstrated by two chemical cases.The experimental results show that the proposed method achieves a great performance on time-series industrial data and outperforms the state-of-the-art approaches.展开更多
Polarization feature is one of the important features of radar targets,which has been used in many fields.In this paper,the grid models of some typical foreign moving targets are constructed on the simulation platform...Polarization feature is one of the important features of radar targets,which has been used in many fields.In this paper,the grid models of some typical foreign moving targets are constructed on the simulation platform,such as glider,cruiser,fixed wing aircraft,and rotorcraft.The electromagnetic scattering characteristics of the moving platforms under the incidence of circular polarization waves are calculated.The typical polarization characteristics which the orthogonal and in-phase components have in the echoes are analyzed and proved.Based on the polarization scattering matrix(PSM)theory,from the point of view of the physical reproduction,the technical status quo that the existing technical approaches are difficult to realize the passive simulation of polarization characteristic of the target is summarized.To solve this problem,combined with the vector synthesis law,the realization mechanism of controllable polarization characteristic of target echoes is proposed,the analytical expressions of polarization control matrix and polarization ratio are deduced,and the controllability of polarization ratio feature in the case of circular polarization is verified by simulation calculation.展开更多
Keyphrase greatly provides summarized and valuable information.This information can help us not only understand text semantics,but also organize and retrieve text content effectively.The task of automatically generati...Keyphrase greatly provides summarized and valuable information.This information can help us not only understand text semantics,but also organize and retrieve text content effectively.The task of automatically generating it has received considerable attention in recent decades.From the previous studies,we can see many workable solutions for obtaining keyphrases.One method is to divide the content to be summarized into multiple blocks of text,then we rank and select the most important content.The disadvantage of this method is that it cannot identify keyphrase that does not include in the text,let alone get the real semantic meaning hidden in the text.Another approach uses recurrent neural networks to generate keyphrases from the semantic aspects of the text,but the inherently sequential nature precludes parallelization within training examples,and distances have limitations on context dependencies.Previous works have demonstrated the benefits of the self-attention mechanism,which can learn global text dependency features and can be parallelized.Inspired by the above observation,we propose a keyphrase generation model,which is based entirely on the self-attention mechanism.It is an encoder-decoder model that can make up the above disadvantage effectively.In addition,we also consider the semantic similarity between keyphrases,and add semantic similarity processing module into the model.This proposed model,which is demonstrated by empirical analysis on five datasets,can achieve competitive performance compared to baseline methods.展开更多
The rearrangement of α-substituted phenyl-α, α′-dimethoxypropanones (R1) was recently proved to he an [1, 3] siqmatropic migration of methoxy group by study of LFER, solvent effect, crossover experiment, and by ot...The rearrangement of α-substituted phenyl-α, α′-dimethoxypropanones (R1) was recently proved to he an [1, 3] siqmatropic migration of methoxy group by study of LFER, solvent effect, crossover experiment, and by other means. The rearrangement catalysed by trace of totuenesulfonic acid gave a negligible value of the Hammett reaction constant. Further experimental results show that the electronic effect of substituent on the aromatic ring for the rearrangement in neutral medium is much greater (Table 1). We propose sigmatropic migration展开更多
Three-dimensional(3D)ordered porous carbon is generally believed to be a promising electromagnetic wave(EMW)absorbing material.However,most research works targeted performance improvement of 3D ordered porous carbon,a...Three-dimensional(3D)ordered porous carbon is generally believed to be a promising electromagnetic wave(EMW)absorbing material.However,most research works targeted performance improvement of 3D ordered porous carbon,and the specific attenuation mechanism is still ambiguous.Therefore,in this work,a novel ultra-light egg-derived porous carbon foam(EDCF)structure has been successfully constructed by a simple carbonization combined with the silica microsphere template-etching process.Based on an equivalent substitute strategy,the influence of pore volume and specific surface area on the electromagnetic parameters and EMW absorption properties of the EDCF products was confirmed respectively by adjusting the addition content and diameter of silica microspheres.As a primary attenuation mode,the dielectric loss originates from the comprehensive effect of conduction loss and polarization loss in S-band and C band,and the value is dominated by polarization loss in X band and Ku band,which is obviously greater than that of conduction loss.Furthermore,in all samples,the largest effective absorption bandwidth of EDCF-3 is 7.12 GHz under the thickness of 2.13 mm with the filling content of approximately 5 wt%,covering the whole Ku band.Meanwhile,the EDCF-7 sample with optimized pore volume and specific surface area achieves minimum reflection loss(RL_(min))of−58.08 dB at 16.86 GHz while the thickness is 1.27 mm.The outstanding research results not only provide a novel insight into enhancement of EMW absorption properties but also clarify the dominant dissipation mechanism for the porous carbon-based absorber from the perspective of objective experiments.展开更多
Theoretical analysis and experimental research on the polarization properties of output light in gyro are carried out to investigate the phenomenon that the amplitude of an output voltage signal is modulated by dither...Theoretical analysis and experimental research on the polarization properties of output light in gyro are carried out to investigate the phenomenon that the amplitude of an output voltage signal is modulated by dither bias in laser gyros consisting of totally reflecting prisms. Taking the effect of prism stress birefringence into account, an analytical formula of the output light intensity in the gyro and the relationship between the polarization parameter and the amplitude modulation of the output signal are obtained and discussed. For the first time, the polarized power value of the output light is adopted as a basis to estimate the output signal amplitude fading extent of laser gyros. Experimental results demonstrate that when the value of polarized power of output light is below 25.5% of that in ideal static case, the standard error is over 0.0337 dBm, and the displacement extent of the prism is higher than 53% of the radius of the beam waist in the gyro cavity, the amplitude modulation extent of gyro output signal can reach up to 16%, which badly influences the measurement accuracy of the laser gyro. Using this polarized power detecting measurement method can repair the gyro immediately during its fabrication process, improve the testing and production efficiency and shorten the product development cycle.展开更多
In this study,the microstructures,mechanical properties,corrosion behaviors,and biocompatibility of extruded magnesium-zirconiumstrontium-holmium(Mg-Zr-Sr-Ho)alloys were comprehensively investigated.The effect of diff...In this study,the microstructures,mechanical properties,corrosion behaviors,and biocompatibility of extruded magnesium-zirconiumstrontium-holmium(Mg-Zr-Sr-Ho)alloys were comprehensively investigated.The effect of different concentrations of Ho on the microstructural characteristics,tensile and compressive properties,corrosion resistance,and biocompatibility were investigated.The microstructures of the extruded Mg-1Zr-0.5Sr-xHo(x=0.5,1.5,and 4 wt.%)alloys consisted ofα-Mg matrix,fineα-Zr particles,and intermetallic phase particles of Mg_(17)Sr_(2) and Ho_(2)Mg mainly distributed at the grain boundaries.Extensive{1012}tensile twins were observed in the partially recrystallized samples of Mg-1Zr-0.5Sr-0.5Ho and Mg-1Zr-0.5Sr-1.5Ho.Further addition of Ho to 4 wt.%resulted in a complete recrystallization due to activation of the particle stimulated nucleation around the Mg_(17)Sr_(2) particles.The evolution of a rare earth(RE)texture was observed with the Ho addition,which resulted in the weakened basal and prismatic textures.Furthermore,a drastic increase of 200%in tensile elongation and 89%in compressive strain was observed with Ho addition increased from 0.5 to 4 wt%,respectively.The tension-compression yield asymmetry was significantly decreased from 0.62 for Mg-1Zr-0.5Sr-0.5Ho to 0.98 for Mg-1Zr-0.5Sr-4Ho due to the weakening of textures.Corrosion analysis of the extruded Mg-Zr-Sr-Ho alloys revealed the presence of pitting corrosion.A minimum corrosion rate of 4.98 mm y^(−1) was observed in Mg-1Zr-0.5Sr-0.5Ho alloy.The enhanced corrosion resistance is observed due to the presence of Ho_(2)O_(3) in the surface film which reduced galvanic effect.The formation of a stabilized surface film due to the Ho_(2)O_(3) was confirmed through the electrical impedance spectroscopy and XPS analysis.An in vitro cytotoxicity assessment revealed good biocompatibility and cell adhesion in relation to SaOS2 cells.展开更多
The mechanical properties of the 2219 aluminum alloy welded joints by vertical-up variant polarity plasma arc welding (VPPAW) with keyhole were analyzed. The tensile strength of welded joints can reach 55% of that of ...The mechanical properties of the 2219 aluminum alloy welded joints by vertical-up variant polarity plasma arc welding (VPPAW) with keyhole were analyzed. The tensile strength of welded joints can reach 55% of that of base metal. The microstructure of weld joints was studied to explain the mechanical properties of the weld. The results show that the intensity of weld center is less than that of HAZ, and the intensity of weld center is the worst. So an advanced welding procedures is presented to reduce the heat input and increase the welding speed. The results in this procedures show that the tensile strength of welded joints reaches more than 60% of that of the parent metal, and the specific elongation does not descend.展开更多
Collective cell groups are organized to form specific patterns that play an important role in various physiological and pathological processes,such as tissue morphogenesis,wound healing,and cancer invasion.Compared to...Collective cell groups are organized to form specific patterns that play an important role in various physiological and pathological processes,such as tissue morphogenesis,wound healing,and cancer invasion.Compared to the behaviors of single cells that have been studied intensively from many aspects(cell migration,adhesion,polarization,proliferation,etc.)and at various length scales(molecular,subcellular,and cellular),the behaviors of multiple cells are less well understood,particularly from a quantitative perspective.In this talk,we present our recent studies of collective polarization and orientation of multiple cells through both experimental measurement and theoretical modeling,including cell behavior on/in 2D and 3D substrate/tissue.We find that collective cell behavior,including polarization,alignment,and migration,is closely related to local stress states in cell layers or tissue,which demonstrates the crucial role of mechanical forces in living organisms.Specifically,cells demonstrate preferential polarization and alignment along the maximum principal stress in the cell layer,and the cell aspect ratio increases with in-plane maximum shear stress,suggesting that the maximum shear stress is the underlying driving force of cell polarization and orientation.This theory of stress-driven cell behaviors of polarization and orientation provides a new perspective for understanding cell behaviors in living organisms and a guideline for tissue engineering in potential biomedical applications.Strikingly,we note that with regard to the polarization and alignment of collective cells,a typical feature of cell morphology is that the cells generally align along the edge of the pattern,which was called edge effect or boundary effect by assuming that the edge plays a role in cell alignment due to a phenomenon of chemistry.However,the edge effect is an obscure explanation.Here we showed that the edge effect could be explained by the theory of stress-driven cell behavior,i.e.,inplane stress-driven cell polarization and alignment.That is,the cell layer has a stress-free boundary condition at the edge,and thus the direction of the maximum principal stress should be precisely along the edge.According to the theory of stress-driven cell polarity,the cells then preferentially align with the edge of the cell layer,independently of the geometry of the pattern.Once there is a force-free condition at the edge or the boundary,the cells align along the edge of the pattern.Otherwise,the cell may not align with the edge;for example,the cells preferentially align in the radial direction of the wound because of the presence of the contractile force by the actin ring at the wound edge,which is in contradiction with the so-called edge effect but consistent with our theory of stress-driven cell polarity.展开更多
According to Xiaodong Song et al.’s study about difference rotation in the Earth’s inner core, a physical model of lunar motion changing the angular momentum of the Earth’s circles is presented in this work. The Lu...According to Xiaodong Song et al.’s study about difference rotation in the Earth’s inner core, a physical model of lunar motion changing the angular momentum of the Earth’s circles is presented in this work. The Lunar motion makes there be a huge gap existing in the core angular momentum between far lunar hemisphere and near lunar hemisphere. The gap results in the difference rota-tion in the Earth’s inner core, meanwhile, it increases the angular velocity of far lunar hemisphere and decreases the angular velocity of near lunar hemisphere. The Earth’s liquid outer core gene-rates an astro-geodynamical effect including the difference rotation among the Earth’s circles. It is found that when the moon moves into the apogee or the perigee of the lunar orbit, and the moon phase is the upper and lower chords (i.e. semi-diameter place), the true anomaly of the moon will change from 270-degree back (or forward) to 90-degree;this results in the mantle shell of the Earth westward, and forms lunisolar precession, the vernal equinox westward and Chandler polar motion.展开更多
文摘Due to the lack of long-range association and spatial location information,fine details and accurate boundaries of complex clothing images cannot always be obtained by using the existing deep learning-based methods.This paper presents a convolutional structure with multi-scale fusion to optimize the step of clothing feature extraction and a self-attention module to capture long-range association information.The structure enables the self-attention mechanism to directly participate in the process of information exchange through the down-scaling projection operation of the multi-scale framework.In addition,the improved self-attention module introduces the extraction of 2-dimensional relative position information to make up for its lack of ability to extract spatial position features from clothing images.The experimental results based on the colorful fashion parsing dataset(CFPD)show that the proposed network structure achieves 53.68%mean intersection over union(mIoU)and has better performance on the clothing parsing task.
基金supported by the National Natural Science Foundation of China(62073140,62073141)the Shanghai Rising-Star Program(21QA1401800).
文摘Fault diagnosis is important for maintaining the safety and effectiveness of chemical process.Considering the multivariate,nonlinear,and dynamic characteristic of chemical process,many time-series-based data-driven fault diagnosis methods have been developed in recent years.However,the existing methods have the problem of long-term dependency and are difficult to train due to the sequential way of training.To overcome these problems,a novel fault diagnosis method based on time-series and the hierarchical multihead self-attention(HMSAN)is proposed for chemical process.First,a sliding window strategy is adopted to construct the normalized time-series dataset.Second,the HMSAN is developed to extract the time-relevant features from the time-series process data.It improves the basic self-attention model in both width and depth.With the multihead structure,the HMSAN can pay attention to different aspects of the complicated chemical process and obtain the global dynamic features.However,the multiple heads in parallel lead to redundant information,which cannot improve the diagnosis performance.With the hierarchical structure,the redundant information is reduced and the deep local time-related features are further extracted.Besides,a novel many-to-one training strategy is introduced for HMSAN to simplify the training procedure and capture the long-term dependency.Finally,the effectiveness of the proposed method is demonstrated by two chemical cases.The experimental results show that the proposed method achieves a great performance on time-series industrial data and outperforms the state-of-the-art approaches.
基金supported by the National Natural Science Foundation of China(11927803A020414).
文摘Polarization feature is one of the important features of radar targets,which has been used in many fields.In this paper,the grid models of some typical foreign moving targets are constructed on the simulation platform,such as glider,cruiser,fixed wing aircraft,and rotorcraft.The electromagnetic scattering characteristics of the moving platforms under the incidence of circular polarization waves are calculated.The typical polarization characteristics which the orthogonal and in-phase components have in the echoes are analyzed and proved.Based on the polarization scattering matrix(PSM)theory,from the point of view of the physical reproduction,the technical status quo that the existing technical approaches are difficult to realize the passive simulation of polarization characteristic of the target is summarized.To solve this problem,combined with the vector synthesis law,the realization mechanism of controllable polarization characteristic of target echoes is proposed,the analytical expressions of polarization control matrix and polarization ratio are deduced,and the controllability of polarization ratio feature in the case of circular polarization is verified by simulation calculation.
文摘Keyphrase greatly provides summarized and valuable information.This information can help us not only understand text semantics,but also organize and retrieve text content effectively.The task of automatically generating it has received considerable attention in recent decades.From the previous studies,we can see many workable solutions for obtaining keyphrases.One method is to divide the content to be summarized into multiple blocks of text,then we rank and select the most important content.The disadvantage of this method is that it cannot identify keyphrase that does not include in the text,let alone get the real semantic meaning hidden in the text.Another approach uses recurrent neural networks to generate keyphrases from the semantic aspects of the text,but the inherently sequential nature precludes parallelization within training examples,and distances have limitations on context dependencies.Previous works have demonstrated the benefits of the self-attention mechanism,which can learn global text dependency features and can be parallelized.Inspired by the above observation,we propose a keyphrase generation model,which is based entirely on the self-attention mechanism.It is an encoder-decoder model that can make up the above disadvantage effectively.In addition,we also consider the semantic similarity between keyphrases,and add semantic similarity processing module into the model.This proposed model,which is demonstrated by empirical analysis on five datasets,can achieve competitive performance compared to baseline methods.
文摘The rearrangement of α-substituted phenyl-α, α′-dimethoxypropanones (R1) was recently proved to he an [1, 3] siqmatropic migration of methoxy group by study of LFER, solvent effect, crossover experiment, and by other means. The rearrangement catalysed by trace of totuenesulfonic acid gave a negligible value of the Hammett reaction constant. Further experimental results show that the electronic effect of substituent on the aromatic ring for the rearrangement in neutral medium is much greater (Table 1). We propose sigmatropic migration
基金supported by the National Natural Science Foundation of China under Grant No.52072196,52002199,52002200,52102106Major Basic Research Program of Natural Science Foundation of Shandong Province under Grant No.ZR2020ZD09+2 种基金the Natural Science Foundation of Shandong Province under Grant No.ZR2019BEM042,ZR2020QE063the Innovation and Technology Program of Shandong Province under Grant No.2020KJA004the Taishan Scholars Program of Shandong Province under No.ts201511034
文摘Three-dimensional(3D)ordered porous carbon is generally believed to be a promising electromagnetic wave(EMW)absorbing material.However,most research works targeted performance improvement of 3D ordered porous carbon,and the specific attenuation mechanism is still ambiguous.Therefore,in this work,a novel ultra-light egg-derived porous carbon foam(EDCF)structure has been successfully constructed by a simple carbonization combined with the silica microsphere template-etching process.Based on an equivalent substitute strategy,the influence of pore volume and specific surface area on the electromagnetic parameters and EMW absorption properties of the EDCF products was confirmed respectively by adjusting the addition content and diameter of silica microspheres.As a primary attenuation mode,the dielectric loss originates from the comprehensive effect of conduction loss and polarization loss in S-band and C band,and the value is dominated by polarization loss in X band and Ku band,which is obviously greater than that of conduction loss.Furthermore,in all samples,the largest effective absorption bandwidth of EDCF-3 is 7.12 GHz under the thickness of 2.13 mm with the filling content of approximately 5 wt%,covering the whole Ku band.Meanwhile,the EDCF-7 sample with optimized pore volume and specific surface area achieves minimum reflection loss(RL_(min))of−58.08 dB at 16.86 GHz while the thickness is 1.27 mm.The outstanding research results not only provide a novel insight into enhancement of EMW absorption properties but also clarify the dominant dissipation mechanism for the porous carbon-based absorber from the perspective of objective experiments.
基金Project supported by the National High Technology Research and Development Program of China(Grant No.2006AA12Z144)
文摘Theoretical analysis and experimental research on the polarization properties of output light in gyro are carried out to investigate the phenomenon that the amplitude of an output voltage signal is modulated by dither bias in laser gyros consisting of totally reflecting prisms. Taking the effect of prism stress birefringence into account, an analytical formula of the output light intensity in the gyro and the relationship between the polarization parameter and the amplitude modulation of the output signal are obtained and discussed. For the first time, the polarized power value of the output light is adopted as a basis to estimate the output signal amplitude fading extent of laser gyros. Experimental results demonstrate that when the value of polarized power of output light is below 25.5% of that in ideal static case, the standard error is over 0.0337 dBm, and the displacement extent of the prism is higher than 53% of the radius of the beam waist in the gyro cavity, the amplitude modulation extent of gyro output signal can reach up to 16%, which badly influences the measurement accuracy of the laser gyro. Using this polarized power detecting measurement method can repair the gyro immediately during its fabrication process, improve the testing and production efficiency and shorten the product development cycle.
基金the financial support for this research by the Australian Research Council(ARC)through the Future Fellowship(FT160100252)the Discovery Project(DP170102557)。
文摘In this study,the microstructures,mechanical properties,corrosion behaviors,and biocompatibility of extruded magnesium-zirconiumstrontium-holmium(Mg-Zr-Sr-Ho)alloys were comprehensively investigated.The effect of different concentrations of Ho on the microstructural characteristics,tensile and compressive properties,corrosion resistance,and biocompatibility were investigated.The microstructures of the extruded Mg-1Zr-0.5Sr-xHo(x=0.5,1.5,and 4 wt.%)alloys consisted ofα-Mg matrix,fineα-Zr particles,and intermetallic phase particles of Mg_(17)Sr_(2) and Ho_(2)Mg mainly distributed at the grain boundaries.Extensive{1012}tensile twins were observed in the partially recrystallized samples of Mg-1Zr-0.5Sr-0.5Ho and Mg-1Zr-0.5Sr-1.5Ho.Further addition of Ho to 4 wt.%resulted in a complete recrystallization due to activation of the particle stimulated nucleation around the Mg_(17)Sr_(2) particles.The evolution of a rare earth(RE)texture was observed with the Ho addition,which resulted in the weakened basal and prismatic textures.Furthermore,a drastic increase of 200%in tensile elongation and 89%in compressive strain was observed with Ho addition increased from 0.5 to 4 wt%,respectively.The tension-compression yield asymmetry was significantly decreased from 0.62 for Mg-1Zr-0.5Sr-0.5Ho to 0.98 for Mg-1Zr-0.5Sr-4Ho due to the weakening of textures.Corrosion analysis of the extruded Mg-Zr-Sr-Ho alloys revealed the presence of pitting corrosion.A minimum corrosion rate of 4.98 mm y^(−1) was observed in Mg-1Zr-0.5Sr-0.5Ho alloy.The enhanced corrosion resistance is observed due to the presence of Ho_(2)O_(3) in the surface film which reduced galvanic effect.The formation of a stabilized surface film due to the Ho_(2)O_(3) was confirmed through the electrical impedance spectroscopy and XPS analysis.An in vitro cytotoxicity assessment revealed good biocompatibility and cell adhesion in relation to SaOS2 cells.
文摘The mechanical properties of the 2219 aluminum alloy welded joints by vertical-up variant polarity plasma arc welding (VPPAW) with keyhole were analyzed. The tensile strength of welded joints can reach 55% of that of base metal. The microstructure of weld joints was studied to explain the mechanical properties of the weld. The results show that the intensity of weld center is less than that of HAZ, and the intensity of weld center is the worst. So an advanced welding procedures is presented to reduce the heat input and increase the welding speed. The results in this procedures show that the tensile strength of welded joints reaches more than 60% of that of the parent metal, and the specific elongation does not descend.
基金supported by the National Natural Science Foundation of China ( 11772055,11532009)
文摘Collective cell groups are organized to form specific patterns that play an important role in various physiological and pathological processes,such as tissue morphogenesis,wound healing,and cancer invasion.Compared to the behaviors of single cells that have been studied intensively from many aspects(cell migration,adhesion,polarization,proliferation,etc.)and at various length scales(molecular,subcellular,and cellular),the behaviors of multiple cells are less well understood,particularly from a quantitative perspective.In this talk,we present our recent studies of collective polarization and orientation of multiple cells through both experimental measurement and theoretical modeling,including cell behavior on/in 2D and 3D substrate/tissue.We find that collective cell behavior,including polarization,alignment,and migration,is closely related to local stress states in cell layers or tissue,which demonstrates the crucial role of mechanical forces in living organisms.Specifically,cells demonstrate preferential polarization and alignment along the maximum principal stress in the cell layer,and the cell aspect ratio increases with in-plane maximum shear stress,suggesting that the maximum shear stress is the underlying driving force of cell polarization and orientation.This theory of stress-driven cell behaviors of polarization and orientation provides a new perspective for understanding cell behaviors in living organisms and a guideline for tissue engineering in potential biomedical applications.Strikingly,we note that with regard to the polarization and alignment of collective cells,a typical feature of cell morphology is that the cells generally align along the edge of the pattern,which was called edge effect or boundary effect by assuming that the edge plays a role in cell alignment due to a phenomenon of chemistry.However,the edge effect is an obscure explanation.Here we showed that the edge effect could be explained by the theory of stress-driven cell behavior,i.e.,inplane stress-driven cell polarization and alignment.That is,the cell layer has a stress-free boundary condition at the edge,and thus the direction of the maximum principal stress should be precisely along the edge.According to the theory of stress-driven cell polarity,the cells then preferentially align with the edge of the cell layer,independently of the geometry of the pattern.Once there is a force-free condition at the edge or the boundary,the cells align along the edge of the pattern.Otherwise,the cell may not align with the edge;for example,the cells preferentially align in the radial direction of the wound because of the presence of the contractile force by the actin ring at the wound edge,which is in contradiction with the so-called edge effect but consistent with our theory of stress-driven cell polarity.
文摘According to Xiaodong Song et al.’s study about difference rotation in the Earth’s inner core, a physical model of lunar motion changing the angular momentum of the Earth’s circles is presented in this work. The Lunar motion makes there be a huge gap existing in the core angular momentum between far lunar hemisphere and near lunar hemisphere. The gap results in the difference rota-tion in the Earth’s inner core, meanwhile, it increases the angular velocity of far lunar hemisphere and decreases the angular velocity of near lunar hemisphere. The Earth’s liquid outer core gene-rates an astro-geodynamical effect including the difference rotation among the Earth’s circles. It is found that when the moon moves into the apogee or the perigee of the lunar orbit, and the moon phase is the upper and lower chords (i.e. semi-diameter place), the true anomaly of the moon will change from 270-degree back (or forward) to 90-degree;this results in the mantle shell of the Earth westward, and forms lunisolar precession, the vernal equinox westward and Chandler polar motion.