We here report a high system detection efficiency(SDE)superconducting single-photon detector(SSPD)at 2μm wavelength.The device integrates a SiO_(2)/Ta_(2)O_(5)distributed Bragg reflector(DBR)and a sandwich-structured...We here report a high system detection efficiency(SDE)superconducting single-photon detector(SSPD)at 2μm wavelength.The device integrates a SiO_(2)/Ta_(2)O_(5)distributed Bragg reflector(DBR)and a sandwich-structured double-layer NbN nanowire to enhance the optical absorption efficiency.A cold development technique is implemented to optimize the superconducting nanowires with sub-40-nm linewidths,thus enhancing the intrinsic detection efficiency(IDE).The fabricated SSPD shows an SDE exceeding 90% at 2μm wavelength.Moreover,the detector allows an operational working temperature of 2.2 K provided by a compact GM cryo-cooler.This detector delivers excellent performance at the 2μm wavelength,and its optimized structural design implies promising potential for extending detection toward longer infrared bands.It thus holds value for advancing high-sensitivity quantum technologies,mid-infrared optical communications,and dark matter detection research.展开更多
Ferroptosis is a novel form of cell death driven by oxidative damage,and is implicated in various pathological conditions,including neurodegenerative diseases,retinal damage,and ischemia-reperfusion injury of organs.I...Ferroptosis is a novel form of cell death driven by oxidative damage,and is implicated in various pathological conditions,including neurodegenerative diseases,retinal damage,and ischemia-reperfusion injury of organs.Inhibiting ferroptosis has shown great promise as a therapeutic strategy for these diseases,underscoring the urgent need to develop effective ferroptosis inhibitors.Although Ferrostatin-1(Fer-1)is a potent ferroptosis inhibitor,its susceptibility to oxidation and metabolic inactivation limits its clinical utility.In this study,the accumulation of peroxides and the resulting oxidative damage in the cellular microenvironment during ferroptosis were utilized to design Ferrostatin-1 prodrugs with reactive oxygen species-responsive features.This approach led to the development of a series of ferroptosis inhibitors that were capable of recognizing oxidative damage in diseased areas,allowing for targeted release and improved stability.The novel compounds demonstrated significant inhibitory effects and selectivity against RSL-3-induced ferroptosis in HK-2 cells,with compound a1 exhibiting an EC50 of 15.4�0.7μM,outperforming Fer-1.These compounds effectively identify the oxidative microenvironment associated with ferroptosis,enabling the targeted release of Fer-1,which prevents lipid peroxide accumulation and inhibits ferroptosis.This strategy holds promise for treating diseases related to ferroptosis,offering a targeted and intelligent therapeutic approach.展开更多
Background:Parkinson’s disease(PD)is a neurodegenerative disorder characterized by the degeneration of dopaminergic neurons in the substantia nigra(SN).Activation of the neuroinflammatory response has a pivotal role ...Background:Parkinson’s disease(PD)is a neurodegenerative disorder characterized by the degeneration of dopaminergic neurons in the substantia nigra(SN).Activation of the neuroinflammatory response has a pivotal role in PD.Mesenchymal stem cells(MSCs)have emerged as a promising therapeutic approach for various nerve injuries,but there are limited reports on their use in PD and the underlying mechanisms remain unclear.Methods:We investigated the effects of clinical-grade hypoxia-preconditioned olfactory mucosa(hOM)-MSCs on neural functional recovery in both PD models and patients,as well as the preventive effects on mouse models of PD.To assess improvement in neuroinflammatory response and neural functional recovery induced by hOM-MSCs exposure,we employed single-cell RNA sequencing(scRNA-seq),assay for transposase accessible chromatin with high-throughput sequencing(ATAC-seq)combined with full-length transcriptome isoform-sequencing(ISO-seq),and functional assay.Furthermore,we present the findings from an initial cohort of patients enrolled in a phaseⅠfirstinhuman clinical trial evaluating the safety and efficacy of intraspinal transplantation of hOM-MSC transplantation into severe PD patients.Results:A functional assay identified that transforming growth factor-β1(TGF-β1),secreted from hOM-MSCs,played a critical role in modulating mitochondrial function recovery in dopaminergic neurons.This effect was achieved through improving microglia immune regulation and autophagy homeostasis in the SN,which are closely associated with neuroinflammatory responses.Mechanistically,exposure to hOM-MSCs led to an improvement in neuroinflammation and neural function recovery partially mediated by TGF-β1 via activation of the anaplastic lymphoma kinase/phosphatidylinositol-3-kinase/protein kinase B(ALK/PI3K/Akt)signaling pathway in microglia located in the SN of PD patients.Furthermore,intraspinal transplantation of hOM-MSCs improved the recovery of neurologic function and regulated the neuroinflammatory response without any adverse reactions observed in patients with PD.Conclusions:These findings provide compelling evidence for the involvement of TGF-β1 in mediating the beneficial effects of hOM-MSCs on neural functional recovery in PD.Treatment and prevention of hOM-MSCs could be a promising and effective neuroprotective strategy for PD.Additionally,TGF-β1 may be used alone or combined with hOM-MSCs therapy for treating PD.展开更多
Using comprehensive records from the World Spider Catalog,this study presents an in-depth,data-driven analysis of global trends in spider taxonomy,revealing an exceptional acceleration during the first quarter of the ...Using comprehensive records from the World Spider Catalog,this study presents an in-depth,data-driven analysis of global trends in spider taxonomy,revealing an exceptional acceleration during the first quarter of the 21st century.Of the more than 53000 extant spider species described since 1757,19159—approximately 36%—were described during the last 25 years.In 59 families,the number of new species described during this period exceeded the total accumulated over the entire 20th century.Asia emerged as the leading continental hotspot for spider discovery,with China at the forefront.The number of species described in China during the 25-year window was 1.5 times greater than the combined total documented over the preceding 243 years,with Chinese arachnologists responsible for 23.9%of all new species described in the last 25 years.Three taxonomists—Eugène Simon,Norman Platnick,and Shu-Qiang Li—rank as the most prolific contributors to spider systematics in history.These findings reflect a shift in the global center of arachnological research and underscore the growing scientific output from China.Patterns were examined from three complementary angles:temporal acceleration in species descriptions,individual contributions of leading taxonomists,and the emergence of Chinese arachnology as a dominant force in global taxonomy.Our analysis also emphasizes the critical role of sustained international collaboration in advancing biodiversity discovery.展开更多
As battlefield scale enlarges,cross-platform collaborative combat provides an appealing paradigm for modern warfare.Complicated constraints and vast solution space pose great challenge for reasonable and efficient mis...As battlefield scale enlarges,cross-platform collaborative combat provides an appealing paradigm for modern warfare.Complicated constraints and vast solution space pose great challenge for reasonable and efficient mission planning,where path planning and target assignment are tightly coupled.In this paper,we focus on UAV mission planning under carrier delivery mode(e.g.,by aircraft carrier,ground vehicle,or transport aircraft) and design a three-layer hierarchical solution framework.In the first layer,we simultaneously determine delivery points and target set division by clustering.To address the safety concerns of radar risk and UAV endurance,an improved density peak clustering algorithm is developed by constraint fusio n.In the second layer,mission planning within each cluster is viewed as a coope rative multiple-task assignment problem.A hybrid heuristic algorithm that integrates a voting-based heuristic solution generation strategy(VHSG) and a stochastic variable neighborhood search(SVNS),called VHSG-SVNS,is proposed for rapid solution.Based on the results of the first two layers,the third layer transforms carrier path planning into a multiple-vehicle routing problem with time window.The cost between any two nodes is calculated by the A~* algorithm,and the genetic algorithm is then implemented to determine the global route.Finally,a practical mission scenario containing 200 targets is used to validate the effectiveness of the designed framework,where three layers cooperate well with each other to generate satisfactory combat scheduling.Comparisons are made in each layer to highlight optimum-seeking capability and efficiency of the proposed algorithms.Works done in this paper provide a simple but efficient solution framework for cross-platform cooperative mission planning problems,and can be potentially extended to other applications such as post-disaster search and rescue,forest surveillance and firefighting,logistics pick and delivery,etc.展开更多
BACKGROUND Natural killer(NK)/T-cell non-Hodgkin's lymphoma(NHL)in the nasal cavities and paranasal sinuses accounts for approximately 10%of all lymphomas,and the occurrence of nasal NHL is related to Epstein-Barr...BACKGROUND Natural killer(NK)/T-cell non-Hodgkin's lymphoma(NHL)in the nasal cavities and paranasal sinuses accounts for approximately 10%of all lymphomas,and the occurrence of nasal NHL is related to Epstein-Barr virus infection.AIM To explore the anxiety and depression status of patients with NK/T-cell NHL in the nasal cavities and paranasal sinuses and analyzes the relevant influencing factors.METHODS A retrospective analysis was performed,which included 30 patients with primary nasal NK/T-cell NHL treated in Shaanxi Provincial People’s Hospital from January 2017 to January 2023.An additional 50 healthy volunteers were selected as the control group.Both groups were assessed using the self-rating anxiety scale(SAS)and Self-rating(SDS).SDS and SAS scores of patients with NHL at different disease stages were analyzed,and they were further grouped into negative emotion(NE)(n=19)and non-NE(n=11)groups based on their depression and anxiety.Factors affecting the occurrence of NEs in patients with NHL were analyzed using univariate and multivariate logistic regression models.RESULTS Patients with NHL exhibited higher SDS and SAS scores than healthy controls.Moreover,patients with NHL at stages III and IV had higher SDS and SAS scores than those in stage I.Among the 30 patients,there were 13 patients with depression(43.3%),16 patients with anxiety(53.3%),and 10 patients with both anxiety and depression(33.3%).Univariate analysis identified a higher proportion of people in the NE group with stage III-IV NHL,an educational level≤high school,and a monthly household income<5000 yuan compared with the non-NE group.Multiple logistic regression analysis further revealed that stage III-IV was a risk factor for NEs in patients with NHL.CONCLUSION The stage of NK/T-cell NHL in nasal cavities and paranasal sinuses is closely related to patient anxiety and depression.The higher the staging,the greater the incidence of anxiety and depression.展开更多
Due to the high flexibility of Unmanned Aerial Vehicles(UAVs),equipping Mobile Edge Computing(MEC)servers on UAVs can effectively and rapidly handle the high computing requirements of computation-intensive tasks.Howev...Due to the high flexibility of Unmanned Aerial Vehicles(UAVs),equipping Mobile Edge Computing(MEC)servers on UAVs can effectively and rapidly handle the high computing requirements of computation-intensive tasks.However,the Line-of-Sight(LoS)transmission between the UAV and ground users makes the offloading information be easily monitored.Therefore,this paper proposes a covert communication scheme against a flying warden in UAV-assisted MEC system.In the proposed scheme,the UAV server assists ground users in completing the computation of offloading tasks.To reduce the possibility of the flying warden detecting the transmission behavior of ground users to the UAV server,a ground jamming device sends jamming signals to the flying warden.The minimum computing capacity of the system is maximized by jointly optimizing ground users’resources and the UAV server’s trajectory under the constraint of system covertness.Due to the multivariable coupling,the optimization problem is non-convex.The optimization problem is first transformed into a tractable form,and then the optimizing solution is iteratively obtained using Successive Convex Approximation(SCA)and Block Coordinate Descent(BCD)algorithms.Numerical results show that,compared to the benchmark schemes,the proposed scheme effectively enhances the computing capacity of the system while meeting the system’s covertness requirements.展开更多
[Objectives]To elucidate the spatial variation characteristics and fertility status of soil nutrients in small-scale mountain tea gardens and to inform precise fertilization and nutrient management practices in these ...[Objectives]To elucidate the spatial variation characteristics and fertility status of soil nutrients in small-scale mountain tea gardens and to inform precise fertilization and nutrient management practices in these tea gardens.[Methods]Based on soil nutrient data collected from 72 sampling points in the tea garden in 2021,which covers an area of approximately 2.4 km^(2),the spatial variation characteristics were analyzed using geostatistical methods.Spatial distribution maps of soil pH,total nitrogen,available phosphorus,and available potassium were generated employing the ordinary Kriging interpolation method in Surfer 23 software.Furthermore,a quantitative assessment of soil fertility was performed utilizing the fuzzy comprehensive evaluation method.[Results]The majority of the soil in the tea garden was acidic.The average values for pH,organic matter,total nitrogen,available phosphorus,and available potassium were 4.66,14.4 g/kg,0.9 g/kg,6.2 mg/kg,and 78.1 mg/kg,respectively.The pH exhibited the lowest coefficient of variation at 12.85%,indicating low variability.The coefficients of variation for organic matter,total nitrogen,and available potassium ranged from 31.94%to 49.88%,reflecting moderate variability.In contrast,the coefficient of variation for available phosphorus was 243.41%,indicating high variability.The distribution of soil pH and available phosphorus in the study area was relatively uniform.In contrast,total nitrogen content exhibited a spatial pattern characterized by higher concentrations in the western region and lower concentrations in the eastern region.Organic matter content displayed a spatial distribution pattern with lower values centrally and higher values along the periphery.The distribution of available potassium content was marked by several pronounced"elevations"and"depressions",with notably lower levels observed in the northeastern region of the garden.Total nitrogen and organic matter were the most significant contributors to the integrated fertility index(I_(IFI)),each with a weight value of 0.29,whereas pH had the lowest weight value of 0.14.The proportions of tea garden soils categorized under I_(IFI)grades I to V were 0.26%,69.55%,25.89%,4.30%,and 0.0022%,respectively.[Conclusions]It is recommended that the application of phosphorus fertilizer should be reduced in the study area,whereas the use of potassium fertilizer should be increased in the northeastern region.Additionally,the incorporation of organic and nitrogen fertilizers is advised to improve the soil s capacity for water and nutrient retention.展开更多
Interparticle frictional interactions are ubiquitous in colloidal systems,exerting a profound influence on their structural and physical attributes.In this study,we employed Brownian dynamics simulations to explore th...Interparticle frictional interactions are ubiquitous in colloidal systems,exerting a profound influence on their structural and physical attributes.In this study,we employed Brownian dynamics simulations to explore the non-equilibrium dynamics in colloidal systems,focusing particularly on the role of tangential friction and its influence on the macroscopic physical properties of colloids.We found that the disruption of instantaneous time-reversal symmetry by tangential frictional interactions can trigger the self-assembly of colloidal systems into intricate network configurations,and these novel structures exhibit unique depletion force and rheological properties that set them apart from traditional colloidal gel systems.These findings not only help deepen our comprehension of the self-assembly phenomena in non-equilibrium colloidal systems but also offer fresh insights for the development of colloidal materials with tailored characteristics.展开更多
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA0520403)Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)+1 种基金Innovation Program for Quantum Science and Technology(Grant No.2023ZD0300100)the National Natural Science Foundation of China(Grant Nos.U24A20320 and 62401554)。
文摘We here report a high system detection efficiency(SDE)superconducting single-photon detector(SSPD)at 2μm wavelength.The device integrates a SiO_(2)/Ta_(2)O_(5)distributed Bragg reflector(DBR)and a sandwich-structured double-layer NbN nanowire to enhance the optical absorption efficiency.A cold development technique is implemented to optimize the superconducting nanowires with sub-40-nm linewidths,thus enhancing the intrinsic detection efficiency(IDE).The fabricated SSPD shows an SDE exceeding 90% at 2μm wavelength.Moreover,the detector allows an operational working temperature of 2.2 K provided by a compact GM cryo-cooler.This detector delivers excellent performance at the 2μm wavelength,and its optimized structural design implies promising potential for extending detection toward longer infrared bands.It thus holds value for advancing high-sensitivity quantum technologies,mid-infrared optical communications,and dark matter detection research.
基金supported by the Natural Science Foundation of Liaoning Province(2023-MSBA-020)the Fundamental Research Funds for Central Universities(DUT24MS020)Science and Technology Innovation Fund of Dalian(2022JJ13SN073).
文摘Ferroptosis is a novel form of cell death driven by oxidative damage,and is implicated in various pathological conditions,including neurodegenerative diseases,retinal damage,and ischemia-reperfusion injury of organs.Inhibiting ferroptosis has shown great promise as a therapeutic strategy for these diseases,underscoring the urgent need to develop effective ferroptosis inhibitors.Although Ferrostatin-1(Fer-1)is a potent ferroptosis inhibitor,its susceptibility to oxidation and metabolic inactivation limits its clinical utility.In this study,the accumulation of peroxides and the resulting oxidative damage in the cellular microenvironment during ferroptosis were utilized to design Ferrostatin-1 prodrugs with reactive oxygen species-responsive features.This approach led to the development of a series of ferroptosis inhibitors that were capable of recognizing oxidative damage in diseased areas,allowing for targeted release and improved stability.The novel compounds demonstrated significant inhibitory effects and selectivity against RSL-3-induced ferroptosis in HK-2 cells,with compound a1 exhibiting an EC50 of 15.4�0.7μM,outperforming Fer-1.These compounds effectively identify the oxidative microenvironment associated with ferroptosis,enabling the targeted release of Fer-1,which prevents lipid peroxide accumulation and inhibits ferroptosis.This strategy holds promise for treating diseases related to ferroptosis,offering a targeted and intelligent therapeutic approach.
基金supported by the Key Research and Development Program of Hunan Province of China(2020SK2102)the Hunan Provincial Natural Science Foundation of China(2023JJ40420)+5 种基金the Changsha Municipal Natural Science Foundation(kq2208154)the Scientific Research Project of Hunan Provincial Health Commission(B202304088074)the Scientific Research Project of Hunan Provincial Health Commission(202203105045)the National Natural Science Foundation of China(82301435,82201484)the Hunan Provincial Natural Science Foundation of China(2024JJ4083)the Graduate Research and Innovation Project of Hunan Education Department(CX20220528).
文摘Background:Parkinson’s disease(PD)is a neurodegenerative disorder characterized by the degeneration of dopaminergic neurons in the substantia nigra(SN).Activation of the neuroinflammatory response has a pivotal role in PD.Mesenchymal stem cells(MSCs)have emerged as a promising therapeutic approach for various nerve injuries,but there are limited reports on their use in PD and the underlying mechanisms remain unclear.Methods:We investigated the effects of clinical-grade hypoxia-preconditioned olfactory mucosa(hOM)-MSCs on neural functional recovery in both PD models and patients,as well as the preventive effects on mouse models of PD.To assess improvement in neuroinflammatory response and neural functional recovery induced by hOM-MSCs exposure,we employed single-cell RNA sequencing(scRNA-seq),assay for transposase accessible chromatin with high-throughput sequencing(ATAC-seq)combined with full-length transcriptome isoform-sequencing(ISO-seq),and functional assay.Furthermore,we present the findings from an initial cohort of patients enrolled in a phaseⅠfirstinhuman clinical trial evaluating the safety and efficacy of intraspinal transplantation of hOM-MSC transplantation into severe PD patients.Results:A functional assay identified that transforming growth factor-β1(TGF-β1),secreted from hOM-MSCs,played a critical role in modulating mitochondrial function recovery in dopaminergic neurons.This effect was achieved through improving microglia immune regulation and autophagy homeostasis in the SN,which are closely associated with neuroinflammatory responses.Mechanistically,exposure to hOM-MSCs led to an improvement in neuroinflammation and neural function recovery partially mediated by TGF-β1 via activation of the anaplastic lymphoma kinase/phosphatidylinositol-3-kinase/protein kinase B(ALK/PI3K/Akt)signaling pathway in microglia located in the SN of PD patients.Furthermore,intraspinal transplantation of hOM-MSCs improved the recovery of neurologic function and regulated the neuroinflammatory response without any adverse reactions observed in patients with PD.Conclusions:These findings provide compelling evidence for the involvement of TGF-β1 in mediating the beneficial effects of hOM-MSCs on neural functional recovery in PD.Treatment and prevention of hOM-MSCs could be a promising and effective neuroprotective strategy for PD.Additionally,TGF-β1 may be used alone or combined with hOM-MSCs therapy for treating PD.
基金supported by the National Natural Science Foundation of China(NSFC-32500394,32170461,31872193)Liaoning Provincial Doctoral Research Startup Fund Project(2024-BS-109)Basic Scientific Research Projects funded by the Educational Department of Liaoning Province(LJ222510166003)。
文摘Using comprehensive records from the World Spider Catalog,this study presents an in-depth,data-driven analysis of global trends in spider taxonomy,revealing an exceptional acceleration during the first quarter of the 21st century.Of the more than 53000 extant spider species described since 1757,19159—approximately 36%—were described during the last 25 years.In 59 families,the number of new species described during this period exceeded the total accumulated over the entire 20th century.Asia emerged as the leading continental hotspot for spider discovery,with China at the forefront.The number of species described in China during the 25-year window was 1.5 times greater than the combined total documented over the preceding 243 years,with Chinese arachnologists responsible for 23.9%of all new species described in the last 25 years.Three taxonomists—Eugène Simon,Norman Platnick,and Shu-Qiang Li—rank as the most prolific contributors to spider systematics in history.These findings reflect a shift in the global center of arachnological research and underscore the growing scientific output from China.Patterns were examined from three complementary angles:temporal acceleration in species descriptions,individual contributions of leading taxonomists,and the emergence of Chinese arachnology as a dominant force in global taxonomy.Our analysis also emphasizes the critical role of sustained international collaboration in advancing biodiversity discovery.
文摘As battlefield scale enlarges,cross-platform collaborative combat provides an appealing paradigm for modern warfare.Complicated constraints and vast solution space pose great challenge for reasonable and efficient mission planning,where path planning and target assignment are tightly coupled.In this paper,we focus on UAV mission planning under carrier delivery mode(e.g.,by aircraft carrier,ground vehicle,or transport aircraft) and design a three-layer hierarchical solution framework.In the first layer,we simultaneously determine delivery points and target set division by clustering.To address the safety concerns of radar risk and UAV endurance,an improved density peak clustering algorithm is developed by constraint fusio n.In the second layer,mission planning within each cluster is viewed as a coope rative multiple-task assignment problem.A hybrid heuristic algorithm that integrates a voting-based heuristic solution generation strategy(VHSG) and a stochastic variable neighborhood search(SVNS),called VHSG-SVNS,is proposed for rapid solution.Based on the results of the first two layers,the third layer transforms carrier path planning into a multiple-vehicle routing problem with time window.The cost between any two nodes is calculated by the A~* algorithm,and the genetic algorithm is then implemented to determine the global route.Finally,a practical mission scenario containing 200 targets is used to validate the effectiveness of the designed framework,where three layers cooperate well with each other to generate satisfactory combat scheduling.Comparisons are made in each layer to highlight optimum-seeking capability and efficiency of the proposed algorithms.Works done in this paper provide a simple but efficient solution framework for cross-platform cooperative mission planning problems,and can be potentially extended to other applications such as post-disaster search and rescue,forest surveillance and firefighting,logistics pick and delivery,etc.
文摘BACKGROUND Natural killer(NK)/T-cell non-Hodgkin's lymphoma(NHL)in the nasal cavities and paranasal sinuses accounts for approximately 10%of all lymphomas,and the occurrence of nasal NHL is related to Epstein-Barr virus infection.AIM To explore the anxiety and depression status of patients with NK/T-cell NHL in the nasal cavities and paranasal sinuses and analyzes the relevant influencing factors.METHODS A retrospective analysis was performed,which included 30 patients with primary nasal NK/T-cell NHL treated in Shaanxi Provincial People’s Hospital from January 2017 to January 2023.An additional 50 healthy volunteers were selected as the control group.Both groups were assessed using the self-rating anxiety scale(SAS)and Self-rating(SDS).SDS and SAS scores of patients with NHL at different disease stages were analyzed,and they were further grouped into negative emotion(NE)(n=19)and non-NE(n=11)groups based on their depression and anxiety.Factors affecting the occurrence of NEs in patients with NHL were analyzed using univariate and multivariate logistic regression models.RESULTS Patients with NHL exhibited higher SDS and SAS scores than healthy controls.Moreover,patients with NHL at stages III and IV had higher SDS and SAS scores than those in stage I.Among the 30 patients,there were 13 patients with depression(43.3%),16 patients with anxiety(53.3%),and 10 patients with both anxiety and depression(33.3%).Univariate analysis identified a higher proportion of people in the NE group with stage III-IV NHL,an educational level≤high school,and a monthly household income<5000 yuan compared with the non-NE group.Multiple logistic regression analysis further revealed that stage III-IV was a risk factor for NEs in patients with NHL.CONCLUSION The stage of NK/T-cell NHL in nasal cavities and paranasal sinuses is closely related to patient anxiety and depression.The higher the staging,the greater the incidence of anxiety and depression.
基金supported in part by the Zhejiang Provincial Natural Science Foundation of China(No.LR25F010003)in part by the National Natural Science Foundation of China(Nos.62271447,61871348 and 62471090)+1 种基金in part by the Natural Science Foundation of Sichuan Province of China(No.2023NSFSC047)in part by the Fundamental Research Funds for the Provincial Universities of Zhejiang,China(No.RF-C2023008).
文摘Due to the high flexibility of Unmanned Aerial Vehicles(UAVs),equipping Mobile Edge Computing(MEC)servers on UAVs can effectively and rapidly handle the high computing requirements of computation-intensive tasks.However,the Line-of-Sight(LoS)transmission between the UAV and ground users makes the offloading information be easily monitored.Therefore,this paper proposes a covert communication scheme against a flying warden in UAV-assisted MEC system.In the proposed scheme,the UAV server assists ground users in completing the computation of offloading tasks.To reduce the possibility of the flying warden detecting the transmission behavior of ground users to the UAV server,a ground jamming device sends jamming signals to the flying warden.The minimum computing capacity of the system is maximized by jointly optimizing ground users’resources and the UAV server’s trajectory under the constraint of system covertness.Due to the multivariable coupling,the optimization problem is non-convex.The optimization problem is first transformed into a tractable form,and then the optimizing solution is iteratively obtained using Successive Convex Approximation(SCA)and Block Coordinate Descent(BCD)algorithms.Numerical results show that,compared to the benchmark schemes,the proposed scheme effectively enhances the computing capacity of the system while meeting the system’s covertness requirements.
基金Supported by Chongqing Municipal Key Projects for Technological Innovation and Application Development(cstc2019jscx-gksbX0092).
文摘[Objectives]To elucidate the spatial variation characteristics and fertility status of soil nutrients in small-scale mountain tea gardens and to inform precise fertilization and nutrient management practices in these tea gardens.[Methods]Based on soil nutrient data collected from 72 sampling points in the tea garden in 2021,which covers an area of approximately 2.4 km^(2),the spatial variation characteristics were analyzed using geostatistical methods.Spatial distribution maps of soil pH,total nitrogen,available phosphorus,and available potassium were generated employing the ordinary Kriging interpolation method in Surfer 23 software.Furthermore,a quantitative assessment of soil fertility was performed utilizing the fuzzy comprehensive evaluation method.[Results]The majority of the soil in the tea garden was acidic.The average values for pH,organic matter,total nitrogen,available phosphorus,and available potassium were 4.66,14.4 g/kg,0.9 g/kg,6.2 mg/kg,and 78.1 mg/kg,respectively.The pH exhibited the lowest coefficient of variation at 12.85%,indicating low variability.The coefficients of variation for organic matter,total nitrogen,and available potassium ranged from 31.94%to 49.88%,reflecting moderate variability.In contrast,the coefficient of variation for available phosphorus was 243.41%,indicating high variability.The distribution of soil pH and available phosphorus in the study area was relatively uniform.In contrast,total nitrogen content exhibited a spatial pattern characterized by higher concentrations in the western region and lower concentrations in the eastern region.Organic matter content displayed a spatial distribution pattern with lower values centrally and higher values along the periphery.The distribution of available potassium content was marked by several pronounced"elevations"and"depressions",with notably lower levels observed in the northeastern region of the garden.Total nitrogen and organic matter were the most significant contributors to the integrated fertility index(I_(IFI)),each with a weight value of 0.29,whereas pH had the lowest weight value of 0.14.The proportions of tea garden soils categorized under I_(IFI)grades I to V were 0.26%,69.55%,25.89%,4.30%,and 0.0022%,respectively.[Conclusions]It is recommended that the application of phosphorus fertilizer should be reduced in the study area,whereas the use of potassium fertilizer should be increased in the northeastern region.Additionally,the incorporation of organic and nitrogen fertilizers is advised to improve the soil s capacity for water and nutrient retention.
基金the support of the National Natural Science Foundation of China(Grant Nos.12274448,12325405,and 12174390)the National Key R&D Program of China(Grant No.2022YFF0503504)。
文摘Interparticle frictional interactions are ubiquitous in colloidal systems,exerting a profound influence on their structural and physical attributes.In this study,we employed Brownian dynamics simulations to explore the non-equilibrium dynamics in colloidal systems,focusing particularly on the role of tangential friction and its influence on the macroscopic physical properties of colloids.We found that the disruption of instantaneous time-reversal symmetry by tangential frictional interactions can trigger the self-assembly of colloidal systems into intricate network configurations,and these novel structures exhibit unique depletion force and rheological properties that set them apart from traditional colloidal gel systems.These findings not only help deepen our comprehension of the self-assembly phenomena in non-equilibrium colloidal systems but also offer fresh insights for the development of colloidal materials with tailored characteristics.
