Hyperspectral image(HSI)contains a wealth of spectral information,which makes fine classification of ground objects possible.In the meanwhile,overly redundant information in HSI brings many challenges.Specifically,the...Hyperspectral image(HSI)contains a wealth of spectral information,which makes fine classification of ground objects possible.In the meanwhile,overly redundant information in HSI brings many challenges.Specifically,the lack of training samples and the high computational cost are the inevitable obstacles in the design of classifier.In order to solve these problems,dimensionality reduction is usually adopted.Recently,graph-based dimensionality reduction has become a hot topic.In this paper,the graph-based methods for HSI dimensionality reduction are summarized from the following aspects.1)The traditional graph-based methods employ Euclidean distance to explore the local information of samples in spectral feature space.2)The dimensionality-reduction methods based on sparse or collaborative representation regard the sparse or collaborative coefficients as graph weights to effectively reduce reconstruction errors and represent most important information of HSI in the dictionary.3)Improved methods based on sparse or collaborative graph have made great progress by considering global low-rank information,local intra-class information and spatial information.In order to compare typical techniques,three real HSI datasets were used to carry out relevant experiments,and then the experimental results were analysed and discussed.Finally,the future development of this research field is prospected.展开更多
Gravitropism is an essential adaptive response of land plants.Asymmetric auxin gradients across plant organs,interpreted by multiple auxin signaling components including AUXIN RESPONSE FACTOR7(ARF7),trigger differenti...Gravitropism is an essential adaptive response of land plants.Asymmetric auxin gradients across plant organs,interpreted by multiple auxin signaling components including AUXIN RESPONSE FACTOR7(ARF7),trigger differential growth and bending response.However,how this fundamental process is strictly maintained in nature remains unclear.Here,we report that gravity stimulates the transcription of METHYL ESTERASE17(MES17)along the lower side of the hypocotyl via ARF7-dependent auxin signaling.The asymmetric distribution of MES17,a methyltransferase that converts auxin from its inactive form methyl indole-3-acetic acid ester(MeI AA)to its biologically active form free-IAA,enhanced the gradient of active auxin across the hypocotyl,which in turn reversely amplified the asymmetric auxin responses and differential growth that shape gravitropic bending.Taken together,our findings reveal the novel role of MES17-mediated auxin homeostasis in gravitropic responses and identify an ARF7-triggered feedback mechanism that reinforces the asymmetric distribution of active auxin and strictly controls gravitropism in plants.展开更多
Electrochemically converting CO_(2)to value-added multi-carbon(C_(2+))fuels and chemicals is a favorable way to achieve carbon neutrality.Herein,polyaniline/CuO nanosheets(PANI/CuO NSs)hybrid electrocatalysts are deve...Electrochemically converting CO_(2)to value-added multi-carbon(C_(2+))fuels and chemicals is a favorable way to achieve carbon neutrality.Herein,polyaniline/CuO nanosheets(PANI/CuO NSs)hybrid electrocatalysts are developed in order to achieve superior C_(2+)selectivity by imparting PANI functional component to the CuO NSs.The decorated PANI nanoparticles(NPs)can effectively stabilize the*CO intermediates and increase their coverage on the active Cu sites,which facilitates the C-C coupling to form multi-carbon products.Benefiting from the synergetic effect of PANI and CuO NSs,best Faradaic efficiency(FE)for C_(2+)product up to 66.4%at-1.6 V vs.reversible hydrogen electrode(RHE)in a H-cell measurement and 60.0%at 400 mA·cm^(-2)in a flow cell measurement are demonstrated by PANI/CuO NSs-25 sample.More importantly,the C_(2+)selectivity keeps stable even in a continuous measurement time period of 92 h in H-cell measurement.The present study may provide more insights for designing efficient hybrid materials toward superior C_(2+)production from electrocatalytic CO_(2)reduction.展开更多
Imposing phase engineering to porous materials is promising to realize outperforming electrocatalytic performances by taking advantages of the merits of porous nanoarchitecture and heterophase structure.In this work,a...Imposing phase engineering to porous materials is promising to realize outperforming electrocatalytic performances by taking advantages of the merits of porous nanoarchitecture and heterophase structure.In this work,amorphous/crystalline ruthenium oxide(RuO_(2))porous particles with rationally regulated heterophases are successfully prepared by integrating the phase engineering into the porous material synthesis.The resultant defect-rich amorphous/crystalline RuO_(2)porous particles exhibit excellent electrocatalytic performance toward the oxygen evolution reaction,achieving a low overpotential of 165 mV at a current density of 10 mA·cm^(−2)and a high mass activity up to 133.8 mA·cm^(-2)at a low overpotential of 200 mV.This work indicates that the synergistic effect of amorphous/crystalline heterophase and porous structural characteristics enables RuO_(2)to trigger a superior electrocatalytic activity.展开更多
Precise spatiotemporal control of the timing and extent of asymmetric cell divisions(AcDs)is essential for plant development.In the Arabidopsis root,ground tissue maturation involves an additional AcD of the endo-derm...Precise spatiotemporal control of the timing and extent of asymmetric cell divisions(AcDs)is essential for plant development.In the Arabidopsis root,ground tissue maturation involves an additional AcD of the endo-dermis that maintains the inner cell layer as the endodermis and generates the middle cortex to the outside.Through regulation of the cell cycle regulator CYCLIND6;1(CYCD6;1),the transcription factors SCARECROW(SCR)and SHORT-ROOT(SHR)play critical roles in this process.In the present study,we found that loss of function of NAC1,a NAC transcription factor family gene,causes markedly increased periclinal cell divisions in the root endodermis.Importantly,NAC1 directly represses the transcription of CYCD6;1 by recruiting the co-repressor TOPLESS(TPL),creating a fine-tuned mechanism to maintain proper root ground tissue patterning by limiting production of middle cortex cells.Biochemical and genetic analyses further showed that NAC1 physically interacts with SCR and SHR to restrict excessive periclinal cell divisions in the endo-dermis during root middle cortex formation.Although NAC1-TPL is recruited to the CYCD6;1 promoter and represses its transcription in an SCR-dependent manner,NAC1 and SHR antagonize each other to regu-late the expression of CYCD6;1.Collectively,our study provides mechanistic insights into how the NAC1-TPL module integrates with the master transcriptional regulators SCR and SHR to control root ground tissue patterning by fine-tuning spatiotemporal expression of CYCD6;1 in Arabidopsis.展开更多
Pedestrian group detection is a challenging but significant issue in pedestrian flow control and public safety management.To address the issue that most conventional pedestrian grouping models(PGMs)can only identify a...Pedestrian group detection is a challenging but significant issue in pedestrian flow control and public safety management.To address the issue that most conventional pedestrian grouping models(PGMs)can only identify a pedestrian group at a limited distance of less than 2 m,this study extended the pedestrian distance constraint of conventional PGMs with a reconstruction of the normal group detection criterion and development of a novelgroup detection criterion suitable for long-span space.To measure the movement behaviorsimilarity with normal distance,five necessary constraints:velocity difference,moving direction offset,distance limitation,distance fluctuation,and group-keeping duration were studied quantitatively to form the criterion to detect normal groups.Meanwhile,a long-span group detection criterion was proposed with extended distance and direction con-sistency constraints.Therefore,this study proposed an improved PGM that considers long-span spaces(PGMLS).In the PGMLS workflow,the MMTrack algorithm was used to obtainpedestrian trajectories.A difference measurement method based on sequential pattern analysis(SPA)was adopted to analyze the velocity similarity of pedestrians.To validate the proposed grouping model,experiments based on pedestrian movement videos in the exit hall of the Shanghai Hongqiao International Airport were conducted.The results indicate that the proposed model can detect both normal and widely separated pedestrian groups,with a long span range of 2-12 m.展开更多
基金supported by the National Key Research and Development Project(No.2020YFC1512000)the National Natural Science Foundation of China(No.41601344)+2 种基金the Fundamental Research Funds for the Central Universities(Nos.300102320107 and 201924)in part by the General Projects of Key R&D Programs in Shaanxi Province(No.2020GY-060)Xi’an Science&Technology Project(Nos.2020KJRC0126 and 202018)。
文摘Hyperspectral image(HSI)contains a wealth of spectral information,which makes fine classification of ground objects possible.In the meanwhile,overly redundant information in HSI brings many challenges.Specifically,the lack of training samples and the high computational cost are the inevitable obstacles in the design of classifier.In order to solve these problems,dimensionality reduction is usually adopted.Recently,graph-based dimensionality reduction has become a hot topic.In this paper,the graph-based methods for HSI dimensionality reduction are summarized from the following aspects.1)The traditional graph-based methods employ Euclidean distance to explore the local information of samples in spectral feature space.2)The dimensionality-reduction methods based on sparse or collaborative representation regard the sparse or collaborative coefficients as graph weights to effectively reduce reconstruction errors and represent most important information of HSI in the dictionary.3)Improved methods based on sparse or collaborative graph have made great progress by considering global low-rank information,local intra-class information and spatial information.In order to compare typical techniques,three real HSI datasets were used to carry out relevant experiments,and then the experimental results were analysed and discussed.Finally,the future development of this research field is prospected.
基金supported by the National Natural Science Foundation of China(projects 31670275,32061143005,and 31870252)Shandong Natural Science Foundation ZR2021QC067the Specialized Fund for the Basic Research Operating Expenses Program of Shandong University(2017JQ04)。
文摘Gravitropism is an essential adaptive response of land plants.Asymmetric auxin gradients across plant organs,interpreted by multiple auxin signaling components including AUXIN RESPONSE FACTOR7(ARF7),trigger differential growth and bending response.However,how this fundamental process is strictly maintained in nature remains unclear.Here,we report that gravity stimulates the transcription of METHYL ESTERASE17(MES17)along the lower side of the hypocotyl via ARF7-dependent auxin signaling.The asymmetric distribution of MES17,a methyltransferase that converts auxin from its inactive form methyl indole-3-acetic acid ester(MeI AA)to its biologically active form free-IAA,enhanced the gradient of active auxin across the hypocotyl,which in turn reversely amplified the asymmetric auxin responses and differential growth that shape gravitropic bending.Taken together,our findings reveal the novel role of MES17-mediated auxin homeostasis in gravitropic responses and identify an ARF7-triggered feedback mechanism that reinforces the asymmetric distribution of active auxin and strictly controls gravitropism in plants.
文摘Electrochemically converting CO_(2)to value-added multi-carbon(C_(2+))fuels and chemicals is a favorable way to achieve carbon neutrality.Herein,polyaniline/CuO nanosheets(PANI/CuO NSs)hybrid electrocatalysts are developed in order to achieve superior C_(2+)selectivity by imparting PANI functional component to the CuO NSs.The decorated PANI nanoparticles(NPs)can effectively stabilize the*CO intermediates and increase their coverage on the active Cu sites,which facilitates the C-C coupling to form multi-carbon products.Benefiting from the synergetic effect of PANI and CuO NSs,best Faradaic efficiency(FE)for C_(2+)product up to 66.4%at-1.6 V vs.reversible hydrogen electrode(RHE)in a H-cell measurement and 60.0%at 400 mA·cm^(-2)in a flow cell measurement are demonstrated by PANI/CuO NSs-25 sample.More importantly,the C_(2+)selectivity keeps stable even in a continuous measurement time period of 92 h in H-cell measurement.The present study may provide more insights for designing efficient hybrid materials toward superior C_(2+)production from electrocatalytic CO_(2)reduction.
文摘Imposing phase engineering to porous materials is promising to realize outperforming electrocatalytic performances by taking advantages of the merits of porous nanoarchitecture and heterophase structure.In this work,amorphous/crystalline ruthenium oxide(RuO_(2))porous particles with rationally regulated heterophases are successfully prepared by integrating the phase engineering into the porous material synthesis.The resultant defect-rich amorphous/crystalline RuO_(2)porous particles exhibit excellent electrocatalytic performance toward the oxygen evolution reaction,achieving a low overpotential of 165 mV at a current density of 10 mA·cm^(−2)and a high mass activity up to 133.8 mA·cm^(-2)at a low overpotential of 200 mV.This work indicates that the synergistic effect of amorphous/crystalline heterophase and porous structural characteristics enables RuO_(2)to trigger a superior electrocatalytic activity.
基金supported by the National Natural Science Foundation of China(32170338 and 32061143005)Innovative Research Groups of Shandong University(2020QNQT014)+3 种基金the Shandong Province Natural Science Foundation of the Major Basic Research Program(2017C03)(to Z.D.)by the National Natural Science Foundation of China(32170311 and 31970192)the Shandong Province Funds for Excellent Young Scholars(ZR2020YQ19)the Program of Shandong University Qilu Young Scholars(to X.K.).
文摘Precise spatiotemporal control of the timing and extent of asymmetric cell divisions(AcDs)is essential for plant development.In the Arabidopsis root,ground tissue maturation involves an additional AcD of the endo-dermis that maintains the inner cell layer as the endodermis and generates the middle cortex to the outside.Through regulation of the cell cycle regulator CYCLIND6;1(CYCD6;1),the transcription factors SCARECROW(SCR)and SHORT-ROOT(SHR)play critical roles in this process.In the present study,we found that loss of function of NAC1,a NAC transcription factor family gene,causes markedly increased periclinal cell divisions in the root endodermis.Importantly,NAC1 directly represses the transcription of CYCD6;1 by recruiting the co-repressor TOPLESS(TPL),creating a fine-tuned mechanism to maintain proper root ground tissue patterning by limiting production of middle cortex cells.Biochemical and genetic analyses further showed that NAC1 physically interacts with SCR and SHR to restrict excessive periclinal cell divisions in the endo-dermis during root middle cortex formation.Although NAC1-TPL is recruited to the CYCD6;1 promoter and represses its transcription in an SCR-dependent manner,NAC1 and SHR antagonize each other to regu-late the expression of CYCD6;1.Collectively,our study provides mechanistic insights into how the NAC1-TPL module integrates with the master transcriptional regulators SCR and SHR to control root ground tissue patterning by fine-tuning spatiotemporal expression of CYCD6;1 in Arabidopsis.
基金support of the National Natural Science Foundation of China(No.72074170).
文摘Pedestrian group detection is a challenging but significant issue in pedestrian flow control and public safety management.To address the issue that most conventional pedestrian grouping models(PGMs)can only identify a pedestrian group at a limited distance of less than 2 m,this study extended the pedestrian distance constraint of conventional PGMs with a reconstruction of the normal group detection criterion and development of a novelgroup detection criterion suitable for long-span space.To measure the movement behaviorsimilarity with normal distance,five necessary constraints:velocity difference,moving direction offset,distance limitation,distance fluctuation,and group-keeping duration were studied quantitatively to form the criterion to detect normal groups.Meanwhile,a long-span group detection criterion was proposed with extended distance and direction con-sistency constraints.Therefore,this study proposed an improved PGM that considers long-span spaces(PGMLS).In the PGMLS workflow,the MMTrack algorithm was used to obtainpedestrian trajectories.A difference measurement method based on sequential pattern analysis(SPA)was adopted to analyze the velocity similarity of pedestrians.To validate the proposed grouping model,experiments based on pedestrian movement videos in the exit hall of the Shanghai Hongqiao International Airport were conducted.The results indicate that the proposed model can detect both normal and widely separated pedestrian groups,with a long span range of 2-12 m.
